methylnitronitrosoguanidine and Disease-Models--Animal

Helicobacter pylori infection is well accepted to be a very important factor for the development of gastric carcinogenesis in the human stomach. In Mongolian gerbils treated with chemical carcinogens, H. pylori infection enhances glandular stomach carcinogenesis, and eradication of infection and results in curtailment of enhancing effects, particularly at early stages of associated inflammation. A high-salt diet exacerbates the effects of H. pylori infection on gastric carcinogenesis, and these two factors act synergistically to promote the development of gastric cancers in this animal model. However, the bacterium exerts the greater effects. Early acquisition significantly increases gastric chemical carcinogenesis in Mongolian gerbils, as compared to later infection. While heterotopic proliferative glands, hyperplastic and dilated glands localized beneath the muscularis mucosae, frequently develop with H. pylori infection alone in this animal model, they obviously regress on eradication, suggesting a relation to severe gastritis, rather than a malignant character. Furthermore, endocrine cells, positive for chromogranin A, are observed in the heterotopic proliferative glands, in contrast to cancerous lesions which lack endocrine elements. In conclusion, H. pylori is not an initiator, but rather a strong promoter of gastric carcinogenesis, whose eradication, together with reduction in salt intake, might effectively prevent gastric cancer development.

Topics: Adenocarcinoma; Animals; Cocarcinogenesis; Disease Models, Animal; Gerbillinae; Helicobacter Infections; Helicobacter pylori; Humans; Methylnitronitrosoguanidine; Methylnitrosourea; Precancerous Conditions; Sodium Chloride, Dietary; Stem Cells; Stomach Neoplasms

Helicobacter pylori (Hp) was concluded to be 'a definite carcinogen' by WHO/IARC in 1994. We have demonstrated that Hp infection enhances chemical carcinogen-induced stomach carcinogenesis in Mongolian gerbils (MGs) using N-methyl-N'-nitro-N-nitrosoguanidine or N-methyl-N-nitrosourea. Not only well-differentiated but also poorly differentiated and signet ring cell types of cancers are observed, mimicking the human case. Eradication of Hp was found to be effective of preventing enhancing effects. Hp infection alone, without chemical carcinogens, caused submucosal proliferating lesions, but not gastric carcinomas, in contrast to reports that Hp infection alone may act on a complete carcinogen. Precise pathological assessment is required to solve this controversy. Here we demonstrate alleviation of Hp induced gastric lesions with eradication in MGs.

Topics: Animals; Disease Models, Animal; Gastric Mucosa; Gerbillinae; Helicobacter Infections; Helicobacter pylori; Humans; Metaplasia; Methylnitronitrosoguanidine; Methylnitrosourea; Stomach Neoplasms

To explore the 'causal link' between Helicobacter pylori(Hp) infection and stomach carcinogenesis, we have established experimental models of stomach carcinogenesis in Mongolian Gerbils(MGs) using the chemical carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine(MNNG) and N-methyl-N-nitrosourea(MNU). The incidence of adenocarcinoma was significantly higher in animals treated with Hp than in the controls. Eradication of Hp was effective in reducing the incidence of adenocarcinoma. No gastric carcinoma was found without any chemical carcinogen. Hp infection enhances glandular stomach carcinogenesis not only of well-differentiated type but also poorly differentiated type and signet ring cell type. Eradication of Hp, apparently a gastric promoter rather than gastric carcinogen, may be useful as a measure for prevention of stomach cancer.

Topics: Adenocarcinoma; Animals; Carcinogens; Disease Models, Animal; Gerbillinae; Helicobacter Infections; Helicobacter pylori; Humans; Methylnitronitrosoguanidine; Methylnitrosourea; Stomach Neoplasms

Animal models are being used to study the mechanisms by which Helicobacter spp. induce gastric disease. To assess the effects of a natural gastric pathogen, Helicobacter mustelae, in the development of chronic gastritis, premalignancy and cancer, the ferret model was studied under natural and experimental conditions.. H. mustelae-infected ferrets were used to study the metabolism of nitrates/nitrites, which are dietary and endogenously formed substances that have been linked to gastric cancer. The ferret was also manipulated by performing gastric reconstructive surgery to study the processing of nitrite and nitrate and to assess the effect of surgery on gastric pathology. In addition, the ferret was tested for its suitability as an animal model for the induction of gastric cancer by oral dosing with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The influence of these variables on gastric pathology and/or metabolic outcomes was examined, and the results in ferrets were compared to findings in humans.. The ferret appears to be an ideal model for studying various gastric parameters and how these factors influence the development of H. mustelae-associated gastric disease. Gastric reconstructive surgery did not effect nitrite processing or overall severity of gastritis in ferrets. However, a single dose of MNNG (50 mg/kg) produced an unprecedented 90% gastric carcinoma in H. mustelae-infected ferrets. This implies that chronic inflammation induced by the bacterium is a cofactor in gastric carcinogenesis.

Topics: Adenocarcinoma; Animals; Disease Models, Animal; Ferrets; Gastric Mucosa; Gastritis; Helicobacter; Helicobacter Infections; Methylnitronitrosoguanidine; Nitrosamines; Proliferating Cell Nuclear Antigen; Stomach; Stomach Neoplasms

Topics: 2-Acetylaminofluorene; Animals; Cocarcinogenesis; Diet; Disease Models, Animal; Disease Susceptibility; Environment; Glutathione Transferase; Liver Neoplasms, Experimental; Methylnitronitrosoguanidine; Nitrosamines; Precancerous Conditions

Dietary factors are now considered to be among the most important environmental risk determinants for cancer. In addition to epidemiological studies, experimental animal studies are an important tool to investigate dietary modulation in carcinogenesis. Results of recent experimental studies on the effect of some nutrients indicate that vitamin A did show an inverse relation with the occurrence of preneoplastic respiratory lesions but not with respiratory tract tumors in benzo[a]pyrene-induced respiratory carcinogenesis. Dietary fat increases respiratory tract tumors and preneoplastic lesions. In colon carcinogenesis, a fat-fiber interrelation was noticed in 1,2-dimethyl-hydrazine- and N-methyl-N'-nitro-N-nitrosoguanidine-induced tumors. Preliminary results in prostate carcinogenesis indicate that dietary fat did not influence the incidence of prostate cancer in a recently developed rat model. Some possible mechanisms in colon and prostate carcinogenesis are discussed.

Topics: 1,2-Dimethylhydrazine; Androgens; Animals; Benzo(a)pyrene; Colonic Neoplasms; Diet; Dietary Fats; Dietary Fiber; Dietary Proteins; Dimethylhydrazines; Disease Models, Animal; Drug Synergism; Epidemiologic Methods; Humans; Lung Neoplasms; Male; Methylnitronitrosoguanidine; Models, Biological; Prostatic Neoplasms; Vitamin A

The SENCAR mouse stock was selectively bred for eight generations for sensitivity to skin tumor induction by the two-stage tumorigenesis protocol using 7,12-dimethylbenz(a)anthracene (DMBA) as the initiator and 12-O-tetradecanoylphorbol-13-acetate (TPA) as the promoter. The SENCAR mouse was derived by crossing Charles River CD-1 mice with skin-tumor-sensitive mice (STS). The SENCAR mice are much more sensitive to both DMBA tumor initiation and TPA tumor promotion than CD-1, BALB/c, and DBA/2 mice. An even greater difference in the sensitivity to two-stage skin tumorigenesis is apparent between SENCAR and C57BL/6 mice when using DMBA-TPA treatment. However, the SENCAR and C57BL/6 mice have a similar tumor response to DMBA-benzoyl peroxide treatment, suggesting that TPA is not an effective promoter in C57BL/6 mice. The DBA/2 mice respond in a similar manner to the SENCAR mice when using N-methyl-N-nitro-N-nitrosoguanidine (MNNG)-TPA treatment. The SENCAR mouse model provides a good dose-response relationship for many carcinogens used as tumor initiators and for many compounds used as tumor promoter. When compared to other stocks and strains of mice, the SENCAR mouse has one of the largest data bases for carcinogens and promoters.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinogens; Carcinoma; Disease Models, Animal; Drug Evaluation, Preclinical; Methylnitronitrosoguanidine; Mice; Mice, Inbred Strains; Papilloma; Skin Neoplasms; Species Specificity; Tetradecanoylphorbol Acetate

Topics: 1,2-Dimethylhydrazine; Adult; Animals; Azoxymethane; Cholesterol; Cholesterol, Dietary; Cholestyramine Resin; Cocarcinogenesis; Colonic Neoplasms; Diagnosis-Related Groups; Dietary Fats; Dimethylhydrazines; Disease Models, Animal; Epidemiologic Methods; Humans; Methylnitronitrosoguanidine; Methylnitrosourea

Topics: Animals; Carcinogens; Cell Transformation, Neoplastic; Disease Models, Animal; Epithelium; Gastric Mucosa; Humans; Methylnitronitrosoguanidine; Mice; Mucus; Precancerous Conditions; Rats; Stomach; Stomach Neoplasms

Topics: 9,10-Dimethyl-1,2-benzanthracene; Adenocarcinoma; Animals; Cricetinae; Disease Models, Animal; Dogs; Drug Interactions; Guinea Pigs; Haplorhini; Kidney Neoplasms; Liver Neoplasms; Liver Neoplasms, Experimental; Lung Neoplasms; Methylcholanthrene; Methylnitronitrosoguanidine; Mice; Neoplasms, Experimental; Rabbits; Rats; Stomach Neoplasms; Urinary Bladder Neoplasms

Skin tumors chemically induced in mice have provided an important experimental model for studying carcinogenesis and for bioassaying carcinogenic agents. The information obtained from this model suggests that the events leading to tumor formation can be divided into at least two stages, initiation and promotion. A single small dose of carinogen produces initiation which appears to be irreversible. These initiating agents may have to be metabolically activated and can interact with cellular macromolecules. The extent to which they bind to DNA correlates well with their carcinogenicity. Increased DNA replication at the time of or during the first day after these agents have been applied appears to enhance carcinogenesis. Unlike initiation, promotion appears to be reversible and the promoting agents must be applied repeatedly before tumors are formed. Promoters interact with membranes, stimulate and alter genetic expression, and increase the rate of cell proliferation. The knowledge gained from these studies in mouse skin has immeasurably helped the entire field of chemical carcinogenesis. But efforts to determine the cellular and molecular mechanisms involved in the carcinogenic process, particularly in the skin, have been hampered by the difficulties of working on whole animals and by the special problems associated with the biologic and biochemical methods required for this target organ. Such problems, however, can be solved by the use of cell cultures of mouse epidermis which can metabolize and bind carcinogens just as is done in vivo. The fact that epidermal cells in vitro proliferate synchronously should facilitate the study of the relation between the cell cycle and carcinogenesis. These cells repair chemically induced DNA damage by at least two mechanisms, excision repair and base-specific repair. When epidermal cells in vitro are exposed to promoting agents, a proliferative response analogous to that in vivo is elicited, apparently mediated through control of polyamine metabolism. Neoplastic transformation has been induced in these cultures by known skin carcinogens.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Aryl Hydrocarbon Hydroxylases; Benzopyrenes; Carcinogens; Cell Division; Cells, Cultured; Chemical Phenomena; Chemistry; Croton Oil; Culture Media; Disease Models, Animal; DNA, Neoplasm; Drug Synergism; Kinetics; Methylnitronitrosoguanidine; Mice; Ornithine Decarboxylase; RNA, Neoplasm; Skin Neoplasms

Hepatocellular carcinoma is a malignancy with poor clinical prognosis. Hepatic oval cells (HOCs) tend to differentiate into cancerous hepatocellular carcinoma cells (HCCs) in the tumor microenvironment. The purpose of the present study was to explore the role of kangxianruangan granule (KXRG)‑containing serum in inhibiting the differentiation of HOCs into HCCs via the Wnt‑1/β‑catenin signaling pathway. N‑methyl‑N'‑nitro‑N‑nitrosoguanidine (MNNG) was applied to induce the transformation of the rat HOC cell line WB‑F344 into HCCs. The overexpression plasmid, Wnt‑1‑up, was utilized to increase Wnt‑1 expression. Subsequently, high, medium and low concentrations of KXRG were applied to MNNG‑treated WB‑F344 cells to assess the inhibitory effect of KXRG on cell differentiation. Flow cytometry was conducted to detect the cell cycle distribution, apoptotic rate and expression of cytokeratin‑19 (CK‑19) protein in cells. An immunofluorescence double staining protocol was used to detect the expression of Wnt‑1 and β‑catenin. ELISAs were performed to detect α fetoprotein in the cell supernatants. Reverse transcription‑quantitative PCR and western blotting were conducted to detect the mRNA and protein expression levels of Wnt‑1, β‑catenin, Cyclin D1, C‑myc, matrix metalloproteinase‑7 (MMP‑7), Axin2 and epithelial cell adhesion molecule (EpCAM) in cells. Compared with the normal group, the apoptotic rate, proportion of S phase cells, concentration of AFP in the cell supernatant, level of CK‑19 protein, and mRNA and protein expression levels of Wnt‑1, β‑catenin, Cyclin D1, C‑myc, MMP‑7, Axin2 and EpCAM were all significantly increased in the model group. Addition of KXRG significantly reduced the aforementioned indicators compared with the model group. Moreover, Wnt‑1 overexpression further increased the aforementioned indicators compared with the model group, whereas KXRG significantly inhibited these effects. The results indicated that KXRG inhibited the differentiation of HOCs into HCCs via the Wnt‑1/β‑catenin signaling pathway, which suggested the potential clinical application of KXRG for the prevention of hepatocellular carcinoma.

Topics: Animals; Carcinoma, Hepatocellular; Cell Differentiation; Cell Line, Tumor; Cell Transformation, Neoplastic; Disease Models, Animal; Drugs, Chinese Herbal; Humans; Liver; Liver Neoplasms, Experimental; Male; Methylnitronitrosoguanidine; Rats; Tumor Microenvironment; Wnt Signaling Pathway

Elian Granules have been applied in the treatment of precancerous lesions of gastric cancer (PLGC) and achieved good results. However, its exact mechanism remains unclear.. To explore the mechanism of Elian granules in treating PLGC through the mitogen-activated protein kinase (MAPK) signalling pathway based on network pharmacology.. 394 and 4,395 targets were identified in Elian granules and PLGC, respectively. The 190 common targets were mainly enriched in MAPK signalling pathways. The gastric mucosal epithelium was still intact, the glands were arranged regularly, and no goblet cells or apparent inflammatory cell infiltration were observed in the Elian granule group. The expression of p-JNK and p-p38 protein of the Elian granule group (0.83 ± 0.08; 1.18 ± 0.40) was significantly higher than the model group (0.27 ± 0.14; 0.63 ± 0.14) (. Elian granules may play a critical role in the treatment of rat PLGC by up-regulating the expression of p-JNK and p-p38 proteins in the MAPK signalling pathway, thus providing a scientific basis for clinical application.

Topics: Animals; Disease Models, Animal; Drugs, Chinese Herbal; JNK Mitogen-Activated Protein Kinases; Male; MAP Kinase Signaling System; Methylnitronitrosoguanidine; Network Pharmacology; p38 Mitogen-Activated Protein Kinases; Precancerous Conditions; Rats; Rats, Sprague-Dawley; Stomach Neoplasms; Up-Regulation

Zuojin Pill (ZJP) is a classic prescription composed of Coptis chinensis and Tetradium ruticarpum (A.Juss.) T.G.Hartley, which is often used in the treatment of digestive system diseases.. The purpose of this study was to explore the therapeutic effect and potential mechanism of ZJP on chronic atrophic gastritis (CAG) induced by MNNG.. The GES-1 and rat model of CAG was established by MNNG. Detection of cell viability, morphological changes and proliferation of GES-1 by CCK-8 and high content screening (HCS) assay. G-17, IL-8 and TNF-α in rat serum were detected by ELISA kit. The expression of related mRNA and protein on TGF-β1/PI3K/Akt signal axis were detected by RT-PCR and Western blot.. The results showed that ZJP could significantly improve the GES-1 damage induced by MNNG and improve the gastric histomorphology of CAG rats. The intervention of ZJP could significantly reduce the content of G-17 and inflammatory factors IL-8, TNF- α, IL-6 and IL-1β, inhibit the expression of TGF-β1, PI3K and their downstream signals p-Akt, p-mTOR, P70S6K, and promote the expression level of PTEN, LC3-II and Beclin-1.. ZJP has a good therapeutic effect on CAG induced by MNNG, which may be closely related to the inhibition of TGF-β1/PI3K/Akt signal pathway.

Topics: Animals; Beclin-1; Cell Line; Cell Proliferation; Cell Survival; Chronic Disease; Disease Models, Animal; Drugs, Chinese Herbal; Epithelial Cells; Gastritis, Atrophic; Humans; Interleukin-1beta; Interleukin-6; Interleukin-8; Male; Methylnitronitrosoguanidine; Microtubule-Associated Proteins; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; Rats, Sprague-Dawley; Ribosomal Protein S6 Kinases, 70-kDa; Signal Transduction; Transforming Growth Factor beta1; Tumor Necrosis Factor-alpha

Gastric cancer is recognized as one of the most common cancer. In-depth research of gastric precancerous lesions (GPL) plays an important role in preventing the occurrence of gastric cancer. Meanwhile, traditional treatment provides a novel sight in the prevention of occurrence and development of gastric cancer. The current study was designed to assess the effects of therapy with Weipixiao (WPX) decoction on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced GPL rats and the underlying molecular mechanisms. After 10-weeks treatment, all rats were sacrificed. Histopathological changes of gastric tissue were assessed via hematoxylin-eosin (HE) and High-iron diamine-Alcian blue-Periodic acid-Schiff (HID-AB-PAS) staining. To be fully evidenced, RT-qPCR, Western blot and immunohistochemistry were used to detect the expressions of LDHA, CD147, HIF-1α, MCT4, PI3K, AKT, mTOR and miRNA-34a, which were crucial factors for evaluating GPL in the aspect of glycolysis pathogenesis. According to the results of HE and HID-AB-PAS staining, it could be confirmed that MNNG-induced GPL rats were obviously reversed by WPX decoction. Additionally, the increased gene levels of LDHA, CD147, MCT4, PI3K, AKT, mTOR and HIF-1α in model group were down-regulated by WPX decoction, while miRNA-34a expression was decreased and up-regulated by WPX decoction. The significantly increased protein levels of LDHA, CD147, MCT4, PI3K, AKT, mTOR and HIF-1α induced by MNNG were attenuated in rats treated with WPX decoction. In brief, the findings of this study imply that abnormal glycolysis in MNNG-induced GPL rats was relieved by WPX decoction via regulation of the expressions of LDHA, CD147, HIF-1α, MCT4, PI3K, AKT, mTOR and miRNA-34a.

Topics: Animals; Anticarcinogenic Agents; Cytoprotection; Disease Models, Animal; Drugs, Chinese Herbal; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Glycolysis; Male; Methylnitronitrosoguanidine; Precancerous Conditions; Rats, Sprague-Dawley; Signal Transduction; Stomach; Stomach Neoplasms

To explore the changes of Sonic Hedgehog (Shh) signaling pathway in the stomach mucosa during the formation of gastric precancerous lesions.. A total of 72 suckling rats in half genders were randomly and equally divided into the normal group and model group. The rats in the model group were administered with 0.1 ml 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) at the dosage of 800 mg/L for 10 days, whereas the rats in the normal group were similarly administered with normal saline. A total of 12 rats in each group were killed at the end of 10th, 22nd, and 34th weeks in half gender, respectively. Histopathological changes of the gastric mucosa were observed by hematoxylin and eosin (HE) staining; the levels of Shh, Ptch1, Smo, Gli1, Gli2, Gli3, SuFu, Cyclin D1, Cyclin E1, c-Myc, and β-actin mRNAs in the gastric mucosa were determined by real-time polymerase chain reaction; while the protein expression of Shh, Ptch1, Smo, Gli1, SuFu, Cyclin D1, Cyclin E1, c-Myc, and p-c-Myc was detected by western blot analysis.. With the development of atrophy and dysplasia of gastric mucosa, the levels of Shh, Smo, Gli1, Cyclin D1, Cyclin E1, and c-Myc mRNAs increased, while those of Ptch1 and SuFu decreased. The expression of Shh, Smo, Gli1, Cyclin D1, Cyclin E1, and p-c-Myc proteins were elevated, while the expression of Ptch1 and SuFu proteins were decreased, however, without statistical difference.. Shh signaling is activated during the formation of gastric precancerous lesions, which indicates that the Shh signaling pathway participates in the development and progression of gastric precancerous lesions.

Topics: Animals; Atrophy; Disease Models, Animal; Female; Gastric Mucosa; Gene Expression Regulation, Neoplastic; Hedgehog Proteins; Male; Methylnitronitrosoguanidine; Precancerous Conditions; Rats, Sprague-Dawley; RNA, Messenger; Signal Transduction; Stomach Neoplasms; Time Factors

Study shows that signal transducer and activator of transcription 3 (STAT3) can increase the Warburg effect by stimulating hexokinase 2 in breast cancer and upregulate lactate dehydrogenase A and pyruvate dehydrogenase kinase 1 in myeloma. STAT3 and pyruvate kinase M2 (PKM2) can also be activated and enhance the Warburg effect in hepatocellular carcinoma. Precancerous lesions are critical to human and rodent hepatocarcinogenesis. However, the underlying molecular mechanism for the development of liver precancerous lesions remains unknown. We hypothesized that STAT3 promotes the Warburg effect possibly by upregulating p-PKM2 in liver precancerous lesions in rats.. To investigate the mechanism of the Warburg effect in liver precancerous lesions in rats.. A model of liver precancerous lesions was established by a modified Solt-Farber method. The liver pathological changes were observed by HE staining and immunohistochemistry. The transformation of WB-F344 cells induced with N-methyl-N'-nitro-N-nitrosoguanidine and hydrogen peroxide was evaluated by the soft agar assay and aneuploidy. The levels of glucose and lactate in the tissue and culture medium were detected with a spectrophotometer. The protein levels of glutathione S-transferase-π, proliferating cell nuclear antigen (PCNA), STAT3, and PKM2 were examined by Western blot and immunofluorescence.. We found that the Warburg effect was increased in liver precancerous lesions in rats. PKM2 and p-STAT3 were upregulated in activated oval cells in liver precancerous lesions in rats. The Warburg effect, p-PKM2, and p-STAT3 expression were also increased in transformed WB-F344 cells. STAT3 activation promoted the clonal formation rate, aneuploidy, alpha-fetoprotein expression, PCNA expression, G1/S phase transition, the Warburg effect, PKM2 phosphorylation, and nuclear translocation in transformed WB-F344 cells. Moreover, the Warburg effect was inhibited by stattic, a specific inhibitor of STAT3, and further reduced in transformed WB-F344 cells after the intervention for PKM2.. The Warburg effect is initiated in liver precancerous lesions in rats. STAT3 activation promotes the Warburg effect by enhancing the phosphorylation of PKM2 in transformed WB-F344 cells.

Topics: Animals; Cell Line; Cell Transformation, Neoplastic; Cyclic S-Oxides; Disease Models, Animal; Glycolysis; Hepatocytes; Humans; Hydrogen Peroxide; Liver; Liver Neoplasms; Male; Methylnitronitrosoguanidine; Phosphorylation; Precancerous Conditions; Pyruvate Kinase; Rats; Rats, Wistar; STAT3 Transcription Factor; Stem Cells; Up-Regulation

In recent years, Chinese medicine has played an important role in the prognosis of gastric cancer. Precancerous lesions of gastric carcinoma (PLGC) is a class of gastric cancer which is closely related to the gastric mucosal pathology changes in the role of carcinogenic incentives, and plays key role in the progression of normal gastric mucosal cells into gastric cancerous cells. In current experiment, we explore the relationship between Chinese traditional medicine (Xiao Tan He Wei Decoction) and gastric cancer in the PLGC rat animal models and epithelial-mesenchymal transitioned GES-1 cells which were induced useing 1- Methyl-3-nitro-1-nitrosoguanidine (MNNG). PLGC rat model showed significant deterioration in the gastric mucosa with terrible growth rate in body weight and more atypical hyperplasia in gastric mucosa. MC cells, MNNG induced GES-1 cells which epithelial- mesenchymal-transition (EMT)-related proteins have a great change compare with normal GES-1 cells. The cells had characteristics of malignant cells including proliferation, invasion and metastasis ability. Our research founds that Xiao Tan He Wei Decoction could inhibit cell proliferation and increased apoptosis by increase the level of pro-apoptotic proteins like Bax and caspase-3 and decreased the level of anti-apoptotic protein Bcl-2, block the cells in G0/G1 phase simultaneously. Furthermore, Xiao Tan He Wei Decoction could inhibit nuclear factor kappa-light-chain-enhancer (NF-kB) activity and inhibit its transfer from the cytoplasm to the nucleus. However, when we incubated with NF-κB activator PMA, the effect of Xiao Tan He Wei Decoction was reversed. These results suggested that Xiao Tan He Wei Decoction could be used as a method for the treatment of gastric precancerous lesions, and possibly provide a theoretical basis for the clinical treatment of gastric cancer and gastric precancerous lesions.

Topics: Animals; Apoptosis; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cell Transformation, Neoplastic; Disease Models, Animal; Drugs, Chinese Herbal; Epithelial-Mesenchymal Transition; Humans; Hyperplasia; Methylnitronitrosoguanidine; NF-kappa B; Precancerous Conditions; Rats, Wistar; Stomach Neoplasms; Tetradecanoylphorbol Acetate

Chemoprevention strategies against gastric cancer (GC) need to be explored in light of the fact that stomach cancer still occurs in the absence of Helicobacter pylori (HP) infection and following HP eradication. We evaluated the effect of rebamipide on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced carcinogenesis in SD rats. Thirty-nine male rats were divided into four groups based on whether or not they were treated with rebamipide and/or MNNG: Control, Rebamipide, Control-M, and Rebamipide-M groups. From 8 weeks of age, rats in the Control-M and Rebamipide-M groups received MNNG in drinking water for 30 weeks. The Rebamipide and Rebamipide-M groups were administered 5mg/kg/day of rebamipide. At 50 weeks, cancerous lesions were not observed in either the Control or Rebamipide groups. Nine rats in the Control-M group had developed GC, while four rats in the Rebamipide-M group had developed GC. The incidence of cancer in the Rebamipide-M group was significantly less than in the Control-M group (p<0.05), with a trend toward a lower incidence of invasive carcinoma in the Rebamipide-M group. Carcinomatous invasion into the muscularis propria was not observed in the Rebamipide-M group. In conclusion, the present study demonstrates that rebamipide suppresses. MNNG-induced carcinogenesis and may also inhibit progression of cancer in rats.

Topics: Adenocarcinoma; Alanine; Animals; Antioxidants; Carcinogenesis; Carcinogens; Disease Models, Animal; Immunohistochemistry; Male; Methylnitronitrosoguanidine; Quinolones; Rats; Rats, Sprague-Dawley; Stomach Neoplasms

Physical exercise has been shown to be protective against colon carcinogenesis. Physical exercise, however, covers a wide range of modalities, from which different effects on the human body have been reported. We sought to clarify whether aerobic and resistance trainings would differently affect the development of early carcinogenic events in the colon.. Male BALB/c, C57/BL6, and interleukin 10 knockout (IL-10; on C57/BL6 background) mice were exposed to the carcinogen N-methyl-N'-nitro-N-nitrosoguanidine. BALB/c mice were subjected to either aerobic (swimming) or resistance trainings (climbing a ladder with load attached to the tail). C57/BL6 and IL-10 mice only swam.. In BALB/c carcinogen-exposed mice, aerobic and resistance trainings decreased serum creatine kinase levels (P < 0.001). Although aerobic and resistance trainings reduced the generation of lipid thiobarbituric reactive species (P < 0.01 and P < 0.001), only aerobic exercises enhanced serum glutathione levels aside from carcinogenic exposure (P < 0.05). Carcinogen-exposed and aerobic-trained mice developed 36% less colon preneoplastic lesions than its control group (P < 0.05). Aerobic training reduced colonic subepithelial cyclooxygenase-2 expression in carcinogen-exposed mice (P < 0.001). Interestingly, in this same group, colonic IL-10 expression was upregulated sevenfold (P < 0.001). Current findings were confirmed in C57/BL6 carcinogen-exposed mice, in which aerobic training promoted antipreneoplastic effects (P < 0.05). Knocking IL-10 out of C57/BL6 mice abrogated antipreneoplastic effects of aerobic training on the colon tissue (P > 0.05).. IL-10 is a pivotal element for antipreneoplastic effects of aerobic training on the colon.

Topics: Animals; Carcinogens; Colonic Neoplasms; Disease Models, Animal; Humans; Interleukin-10; Male; Methylnitronitrosoguanidine; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Physical Conditioning, Animal; Precancerous Conditions; Resistance Training; Swimming

This study was conducted to assess the preventive effect of Actinidia valvata Dunn (AVD) extract on an animal model of gastrointestinal carcinogenesis on the basis of changes in tumor incidence, cell proliferation, and apoptosis.. Seventy-five male Wistar rats were divided into five different treatment groups with 15 rats in each group. Group I was given normal feed, whereas Groups II to IV were treated with 10% sodium chloride in the first six weeks and 100 ug/mL of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in drinking water for 24 weeks. Group II was then given normal feed, whereas Group III was given AVD extract (0.24 g/kg/day) for 12 weeks. Group IV was given AVD extract from the first week to the 36th week, whereas Group V was treated with AVD extract alone for 36 weeks. All rats were sacrificed at the end of the 36-week experiment and assessed for the presence of gastrointestinal tumors. The occurrence of cancer was evaluated by histology. Bax, Bcl-2, Caspase-3, and cyclinD1 were determined by immunohistochemical staining and Western blotting.. The incidences of gastric cancer were 0% in Group I, 73.3% in Group II, 33.3% in Group III, 26.7% in Group IV, and 0% in Group V. Bcl-2 and cyclinD1 expression was decreased in AVD extract treated groups, whereas Bax and Caspase-3 expression was increased. Comparison with group II revealed significant differences (p<0.01).. AVD extract exhibits an obvious preventive effect on gastrointestinal carcinogenesis induced by MNNG in rats through the regulation of cell proliferation and apoptosis.

Topics: Actinidia; Animals; Apoptosis; Biomarkers, Tumor; Blotting, Western; Cell Proliferation; Disease Models, Animal; Gastrointestinal Neoplasms; Immunoenzyme Techniques; Male; Methylnitronitrosoguanidine; Plant Extracts; Rats; Rats, Wistar

The human pathogen Helicobacter pylori causes inflammation in the stomach of infected hosts, leading in some cases to the development of gastric cancer. Several mouse models have been developed to study Helicobacter-induced carcinogenesis with similarities to gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma (MALToma) in humans. These models require chronic infection of animals with mouse-colonizing isolates of H. pylori or with related gastric Helicobacter spp., such as the canine/feline species Helicobacter felis. Furthermore, consistent with the known influence of host and environmental factors in human gastric cancer, it is possible to manipulate the type and severity of gastric lesions in mouse Helicobacter infection models through the use of different mouse genetic backgrounds and/or by the administration of known cocarcinogens, such as alkylating agents (e.g., N-nitroso-N-methylurea), or even elevated quantities of dietary salt. Here, we describe protocols for the inoculation of mice with gastric Helicobacter spp. and the administration of these cocarcinogens. Furthermore, we will describe the various methodologies used to study gastric inflammation and carcinogenesis in Helicobacter-infected animals.

Topics: Animals; Carcinogens; Cell Proliferation; Culture Media; Culture Techniques; Cytokines; Disease Models, Animal; Drug Interactions; Epithelial Cells; Female; Helicobacter pylori; Male; Methylnitronitrosoguanidine; Methylnitrosourea; Mice; Microbial Viability; Polymerase Chain Reaction; Specimen Handling; Stomach Neoplasms; Urease

The modulation of intracellular nuclear factor-kappaB (NF-κB) signaling pathway involved in the deregulated expression of cell proliferation and cell cycle regulatory molecules is a pragmatic approach for chemoprevention. Eugenol (4-allyl-1-hydroxy-2-methoxybenzene), a natural phenolic constituent of oils of cloves is known to possess attractive remedial features. In the present study, we investigated the modulatory effects of eugenol on NF-κB signaling in a rat model of gastric carcinogenesis induced by N-methyl-N(')-nitro-N-nitrosoguanidine (MNNG) by analysing the expression of nuclear factor-kappaB (NF-κB) family members ((NF-κB (p50 and p65), inhibitor of kappaB alpha (IκBα), phosphorylated IκBα (p-IκBα), IκB kinase β (IKKβ)) and the NF-κB target genes that promote (e.g., cyclin D1, cyclin B and PCNA) or inhibit (e.g., p53, p21, and Gadd45) cell proliferation and cell survival. MNNG-induced gastric tumours were characterized by NF-κB activation that correlated with upregulation of IKKβ, and phosphorylation and degradation of IκBα. Furthermore, upregulation of cyclins and PCNA with downregulation of p21, p53, and Gadd45 suggested that the proliferative advantage in gastric carcinomas is dependent on elevated constitutive NF-κB activity. Administration of eugenol significantly reduced the incidence of MNNG-induced gastric tumours by suppressing NF-κB activation and modulating the expression of NF-κB target genes that regulate cell proliferation and cell survival. The targeting of NF-κB signaling pathway by eugenol may have a significant impact on chemopreventive and therapeutic approaches for cancer.

Topics: Animals; Body Weight; Cell Proliferation; Disease Models, Animal; Drug Screening Assays, Antitumor; Eugenol; Gene Expression Regulation, Neoplastic; Immunohistochemistry; Male; Methylnitronitrosoguanidine; NF-kappa B; Rats; Rats, Wistar; RNA, Messenger; Signal Transduction; Stomach; Stomach Neoplasms

To investigate the chemopreventive effect and mechanisms of epigallocatechin-3-gallate (EGCG) and folic acid on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastrointestinal cancer in rats, and to investigate and compare the combinatorial effects of EGCG and folic acid on the chemoprevention of gastrointestinal carcinogenesis.. A total of 159 healthy male Wistar rats were randomly divided into seven groups to have the MNNG in drink (group M), MNNG in drink and EGCG in the feed (group ME), MNNG in drink and folic acid in the feed (group MF), MNNG in drink and EGCG+folic acid in the feed (group MEF), EGCG in the feed (group E), folic acid in the feed (group F) or normal feed (group C), respectively. At 44 weeks, all the rats were killed and assessed for the presence of gastrointestinal tumor. The occurrence of cancer was evaluated by histology. Ki-67 in cancerous tissues and in situ apoptosis were determined by immunohistochemical staining or terminal deoxyribonucleotide transferase-mediated nick-end labeling (TUNEL) assay, respectively.. The experiment was completed in 157 rats (98.74%). As compared with group M, the tumor incidence of group MEF decreased significantly (P=0.011). Ki-67 expression in cancerous tissues of group ME and MEF also decreased significantly (P=0.038, P=0.009), while apoptosis of group ME, MF and MEF increased significantly (P=0.000, P=0.003, P=0.000).. EGCG combined with folic acid has an obvious chemopreventive effect on gastrointestinal carcinogenesis induced by MNNG in rats.

Topics: Adenocarcinoma; Administration, Oral; Animals; Anticarcinogenic Agents; Apoptosis; Catechin; Cell Proliferation; Disease Models, Animal; Drug Therapy, Combination; Folic Acid; Gastrointestinal Neoplasms; Hematinics; Male; Methylnitronitrosoguanidine; Rats; Rats, Wistar; Sarcoma; Treatment Outcome

Combining apoptosis induction with anti-invasive and anti-angiogenic treatment is gaining increasing attention as a promising strategy for cancer chemoprevention. In the present study, eugenol (4-allyl-2-methoxyphenol) was evaluated for its chemopreventive effects on N-methyl-N(')-nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinogenesis in Wistar rats by analyzing markers of apoptosis, invasion and angiogenesis.. The expressions of markers of apoptosis (Bcl-2, Bcl-xL, Bax, Apaf-1, cytochrome C, caspase-9, caspase-3 and poly(ADP-ribose)polymerase; PARP), invasion (matrix metalloproteinase-2; MMP-2, matrix metalloproteinase-9; MMP-9, reversion-inducing cysteine rich protein with Kazal motifs; RECK and tissue inhibitors of metalloproteinase-2; TIMP-2) and angiogenesis (vascular endothelial growth factor; VEGF and VEGF receptor1; VEGFR1) in stomach tissue of experimental and control animals were measured by gelatin zymogram, immunohistochemical, Western blot and RT-PCR analysis.. Rats administered MNNG developed gastric carcinomas that displayed apoptosis avoidance coupled to upregulation of pro-invasive and angiogenic factors. Administration of eugenol induced apoptosis via the mitochondrial pathway by modulating the Bcl-2 family proteins, Apaf-1, cytochrome C, and caspases and inhibiting invasion, and angiogenesis as evidenced by changes in the activities of MMPs and the expression of MMP-2 and -9, VEGF, VEGFR1, TIMP-2 and RECK.. Phytochemicals such as eugenol that are capable of manipulating the equilibrium between pro- and anti-apoptotic proteins as well as the delicate balance between stimulators and inhibitors of invasion and angiogenesis are attractive candidates for preventing tumour progression.

Topics: Animals; Apoptosis; Blotting, Western; Densitometry; Disease Models, Animal; Eugenol; Gene Expression Regulation, Neoplastic; Immunohistochemistry; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Methylnitronitrosoguanidine; Neoplasm Invasiveness; Neoplasm Proteins; Neovascularization, Pathologic; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; Stomach Neoplasms

Doublecortin and calcium/calmodulin-dependent protein kinase-like-1 (DCAMKL1) is a candidate marker for progenitor cells in the gastrointestinal mucosa. Lineage cells in the gastric mucosa are derived from progenitor cells, but this process can be altered after injury. Therefore, we explored DCAMKL1 expression under pathological conditions.. An immunohistochemical analysis was performed in rat stomach with acute superficial injury, chronic ulcer, intestinal metaplasia and dysplasia.. DCAMKL1 was exclusively expressed in immature quiescent cells in the isthmus of normal fundic glands, where putative progenitor cells are thought to reside. DCAMKL1-positive cells and proliferating cells shed into the lumen after superficial injury and re-appeared during the regenerative process, mainly in the superficial mucosa. In the marginal mucosa around the active ulcer, parietal and chief cells diminished, foveolar hyperplasia was evident, and trefoil factor family 2 (TFF2)/spasmolytic polypeptide-expressing metaplasia (SPEM) emerged at the gland base. DCAMKL1 cells re-emerged in the deep mucosa juxtaposed with SPEM and proliferating cells. In the healing ulcer, the TFF2 cell population expanded and seemed to redifferentiate to chief cells, while proliferating cells and DCAMKL1 cells appeared above and below the TFF2 cells to promote healing. SPEM appeared and PCNA cells increased in the intestinalized mucosa, and DCAMKL1 was expressed in the proximity of the PCNA cells in the deep mucosa. DCAMKL1, PCNA and TFF2 were expressed in different dysplastic cells lining dilated glands near SPEM.. The ultrastructural appearance of DCAMKL1-positive cells and the expression patterns of DCAMKL1 in normal and pathological states indicate that the cells belong to a progenitor cell population. DCAMKL1 expression is closely associated with TFF2/SPEM cells after injury. DCAMKL1 cells repopulate close to proliferating, hyperplastic, metaplastic and dysplastic cells, and the progenitor zone shifts according to the pathological circumstances.

Topics: Acetic Acid; Animals; Biomarkers; Cell Proliferation; Disease Models, Animal; Doublecortin Protein; Doublecortin-Like Kinases; Gastric Mucosa; Intestinal Diseases; Male; Metaplasia; Methylnitronitrosoguanidine; Protein Serine-Threonine Kinases; Rats; Rats, Wistar; Regeneration; Stem Cells; Stomach; Stomach Diseases; Stomach Ulcer; Trefoil Factor-2

Gastric cancer results from a combination of Helicobacter pylori (H pylori) infection, exposure to dietary carcinogens, and predisposing genetic make-up. Because the role of these factors in gastric carcinogenesis cannot be determined readily in human beings, the present study examined the role of an oral carcinogen and H pylori infection in rhesus monkeys.. Gastroscopies were performed in 23 monkeys assigned to 4 groups: controls; nitrosating carcinogen ethyl-nitro-nitrosoguanidine administration alone; inoculation of a virulent H pylori strain alone (H); and ethyl-nitro-nitrosoguanidine in combination with H pylori (EH). Follow-up gastroscopies and biopsies were performed at 3-month intervals for 5 years for pathologic and molecular studies.. Postinoculation, H and EH groups showed persistent infection and antral gastritis. Starting at 2 and 5 years, respectively, gastric intestinal metaplasia and intraepithelial neoplasia developed in 3 EH monkeys but in no other groups. Transcriptional analysis of biopsy specimens at 5 years revealed group-specific expression profiles, with striking changes in EH monkeys, plus a neoplasia-specific expression profile characterized by changes in multiple cancer-associated genes. Importantly, this neoplastic profile was evident in nonneoplastic mucosa, suggesting that the identified genes may represent markers preceding cancer.. Gastric intraglandular neoplasia is induced in primates when H pylori infection is associated with consumption of a carcinogen similar to the nitrosamines found in pickled vegetables, suggesting that H pylori and the carcinogen synergistically induce gastric neoplasia in primates.

Topics: Animals; Biopsy; Carcinogens; Carcinoma in Situ; Cell Transformation, Neoplastic; Cluster Analysis; Diet; Disease Models, Animal; Disease Progression; DNA Repair; Female; Gastritis; Gastroscopy; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Helicobacter Infections; Helicobacter pylori; Macaca mulatta; Male; Metaplasia; Methylnitronitrosoguanidine; Oligonucleotide Array Sequence Analysis; Precancerous Conditions; Stomach Neoplasms; Time Factors

To evaluate the optimal intervention point of a selective cyclooxygenase-2 (COX-2) inhibitor, celecoxib, for inhibiting Helicobacter pylori (H. pylori)-associated gastric carcinogenesis in Mongolian gerbils (MGs).. One hundred and twelve MGs were divided into six groups (A-F). One hundred gerbils were inoculated with H. pylori (groups A-E). Twelve gerbils were inoculated with vehicle broth only (group F). After 4 wk, they were given N'-methyl-N'-nitro-N-nitroso-guanidine (MNNG) (50 microg/mL) in the drinking water for 20 wk. In groups B-E, the animals were given the stock celecoxib (10 mg/kg per day) diet from the 21st, 31st, 21st and 41st week respectively. The periods of administering celecoxib were 30, 20, 20, and 15 wk respectively. On the 51st week, the animals were sacrificed for histological examination. Local PCNA expression was examined by the immunohistochemistry method. The expression of COX-2 protein was assessed by western blot. Analysis used the chi(2) test. The difference was regarded as significant when P value was less than 0.05.. Seventeen percent (17/100) of H. pylori-infected MGs developed gastric cancer. All of these lesions were well-differentiated adenocarcinoma. The incidence rates of adenocarcinoma in groups A-F were 40%, 0%, 0%, 20%, 25%, and 0% respectively. The inflammatory scores were higher in group B than in other groups. There was no inflammatory response noted in group F. Celecoxib treatment resulted in a significant reduction in the proliferation of H. pylori-infected mucosal cells (groups B, C and D) (P < 0.01). The expression of COX-2 protein was significantly attenuated in the groups which were celecoxib-treated for more than 20 wk (groups B, C, D). The groups treated with celecoxib had a significantly lower rate of advanced gastric cancer (34% vs 75%, P < 0.001) There were no sudden deaths in any of the groups.. Short-term treatment with celecoxib has an anti-carcinogenic effect, and resulted in less severe inflammation and inhibited the invasive degree of gastric cancer.

Topics: Adenocarcinoma; Animals; Anticarcinogenic Agents; Celecoxib; Cell Proliferation; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Disease Models, Animal; Drug Administration Schedule; Gastric Mucosa; Gerbillinae; Helicobacter pylori; Methylnitronitrosoguanidine; Neoplasm Invasiveness; Proliferating Cell Nuclear Antigen; Pyrazoles; Stomach Neoplasms; Sulfonamides; Time Factors

We investigated the combinatorial chemopreventive efficacy of Azadirachta indica (AI) and Ocimum sanctum (OS) against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinogenesis, based on changes in oxidant-antioxidant status, cell proliferation, apoptosis and angiogenesis.. Male Wistar rats were assigned to four groups. Rats in groups 1 and 2 received MNNG (150 mg/kg body weight i.g.) three times with a gap of two weeks in between the treatment. Group 2 rats additionally received ethanolic AI (100 mg/kg body weight i.g.) and OS (150 mg/kg body weight i.g.) leaf extract three times per week for 26 weeks. Group 3 animals were given AI and OS leaf extract alone, whereas group 4 served as the control.. Lipid and protein oxidation and status of the antioxidants, superoxide dismutases, catalase, reduced glutathione (GSH) and GSH-dependent enzymes together with markers of proliferation (proliferating cell nuclear antigen [PCNA], glutathione S-transferase-Pi [GST-P]), invasion (cytokeratin [CK]), angiogenesis (vascular endothelial growth factor [VEGF]) and apoptosis (Bcl-2, Bax, cytochrome C and caspase-3) were used to biomonitor chemoprevention. Rats administered MNNG developed forestomach carcinomas that displayed low lipid and protein oxidation coupled to enhanced antioxidant activities, and overexpression of PCNA, GST-P, CK, VEGF and Bcl-2 with downregulation of Bax, cytochrome C and caspase-3. Coadministration of AI and OS extract suppressed MNNG-induced gastric carcinomas accompanied by modulation of the oxidant-antioxidant status, inhibition of cell proliferation and angiogenesis, and induction of apoptosis.. The results of the present study suggest that chemoprevention by AI and OS combination may be mediated by their antioxidant, antiangiogenic, antiproliferative and apoptosis inducing properties.

Topics: Animals; Antioxidants; Apoptosis; Azadirachta; Disease Models, Animal; Male; Methylnitronitrosoguanidine; Neovascularization, Pathologic; Ocimum; Oxidants; Phytotherapy; Plant Extracts; Rats; Rats, Wistar; Stomach Neoplasms

To establish a model of long-term infection with Helicobacter pylori (Hp) in Mongolian gerbil (Meriones unguiculatus), and to investigate if Hp combined with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) has a synergistic effect to induce gastric mucosa injury. To investigate pathological changes of gastric mucosa during long-term Hp infection in Mongolian gerbil model.. 90 healthy male Mongolian gerbils were randomly divided into 4 groups: Hp group (n = 24) undergoing gastric perfusion of Hp suspension of the line NCTC11637 in brain-heart infusion (BHI) 10(8)-10(9) CFU/ml once a day for 10 days and then gastric perfusion of 1 ml normal saline (NS) once a day for 10 days since the 4th week after Hp perfusion, Hp + MNNG group (n = 24) undergoing gastric perfusion of Hp solution once a day for 10 days and then MNNG 1 ml (2 mg/ml) once a day for 10 days, MNNG group (n = 20) undergoing gastric perfusion of BHI once a day for 10 days and then gastric perfusion of MNNC once a day for 10 day since the 4th week after BHI perfusion, and control group (n = 22) undergoing gastric perfusion of BHI once a day for 10 days and then gastric perfusion of NS again once a day for 10 day since the 4th week after the BHI perfusion. 4 and 8 weeks 1 gerbil from the control group and 2 gerbils from the Hp and Hp + MNNG groups each were killed to observe the pathological changes and Hp colonization by liquid-based urease test and Warthin-Starry silver staining. 20 and 40 weeks after the Hp inoculation 10 gerbils from each group were killed to observe the pathology of the gastric mucosa.. (1) A Mongolian gerbil model of long-term Hp infection was successfully established. (2) Hp induced the process progressing from normal gastric mucosa --> chronic atrophic gastritis --> intestinal metaplasia --> dysplasia. Until 40 weeks after Hp infection, the gastric mucosa of the control group remained normal. Twenty weeks after Hp infection 3 gerbils in the Hp group and 1 gerbil in the Hp + MNNC group showed glandular atrophy and intestinal metaplasia respectively, and 40 weeks after infection, glandular atrophy, intestinal metaplasia, and dysplasia at different degrees in the gastric mucosa were seen in the three experimental groups. The pathological changes of the Hp + MNNG group were the most severe. The incidence rates of precancerous lesions of the Hp + MNNG group were significantly higher than those of the other groups, but no gastric carcinoma was found in the experimental animals.. Hp colonizes stably in the glandular gastric mucosa of Mongolian gerbils. The histological changes after infection are similar to those of the Hp infected human being. Hp and MNNG both cause the injury of gastric mucosa. With synergistic effect, the two pathogenic agents attack the gastric mucosa, they cause more severe injury.

Topics: Animals; Disease Models, Animal; Gastric Mucosa; Gerbillinae; Helicobacter Infections; Helicobacter pylori; Humans; Male; Methylnitronitrosoguanidine

Carcinoma of the stomach is reportedly the second most common cancerous condition affecting the general population. Administration of antioxidants is reported to effectively alleviate the risk of gastric carcinoma. Therefore, we assessed the protective role of naringenin, an antioxidant and naturally occurring citrus flavanone, on gastric carcinogenesis induced by MNNG (200 mg/kg body weight) and S-NaCl (1 mL per rat) in Wistar rats (obtained from the Central Animal House Facility, University of Madras, Taramani Campus, Chennai, India). The animals were divided into 5 groups, and the effects of naringenin on simultaneous and posttreated stages of MNNG were tested. Cancer risk was analyzed along with their antioxidant status. The LPO levels in the experimental groups were assessed as an index of oxidative milieu. Altered redox status was subsequently investigated by assaying the superoxide and hydroxyl radicals, the enzymatic antioxidants (SOD, CAT, GPx), and the nonenzymatic antioxidants viz reduced GSH, vitamin C, and vitamin E. In the presence of MNNG, cancer incidence and LPO levels were significantly increased, whereas enzymatic (SOD, CAT, and GPx) and nonenzymatic antioxidant activities (GSH, Vitamins C, and E) were decreased in the treated rats compared with control rats. Administration of naringenin to gastric carcinoma-induced rats largely up-regulated the redox status to decrease the risk of cancer. We conclude that up-regulation of antioxidants by naringenin treatment might be responsible for the anticancer effect in gastric carcinoma.

Topics: Animals; Antineoplastic Agents; Antioxidants; Carcinoma; Cysteine; Disease Models, Animal; Flavanones; Gastric Mucosa; Lipid Peroxidation; Male; Methylnitronitrosoguanidine; Oxidation-Reduction; Random Allocation; Rats; Rats, Wistar; Reactive Oxygen Species; Stomach Neoplasms; Superoxide Dismutase; Thiobarbituric Acid Reactive Substances; Weight Loss

Combination treatment with sodium nitrite (NaNO(2)) and ascorbic acid (AsA) is well known to promote forestomach carcinogenesis in rats and weakly enhance esophageal carcinogenesis under acid reflux conditions. Nitric oxide generation and oxidative DNA damage are considered to be related to the enhancement of carcinogenesis. The purpose of the present study was to investigate whether oxidative DNA damage-associated genotoxicity and tumor initiating potential are involved in the carcinogenesis. In the bacterial reverse mutation assay using Escherichia coli deficient in the mutM gene encoding 8-hydroxydeoxyguanosine (8-OHdG) DNA glycosylase, the combination with NaNO(2) and AsA increased the mutation frequency dramatically, slight increase being evident in the parental strain. In vivo, a significant increase in 8-OHdG levels in the rat forestomach epithelium occurred at 24 h after combined treatment. Six-week-old F344 male rats were given drinking water containing 0.2% NaNO(2) and a diet supplemented with 1% AsA in combination, or the chemicals individually or basal diet alone for 12 weeks. After an interval of 2 weeks, they received 1% butylated hydroxyanisole in the diet for promotion until the end of weeks 52 and 78. Although one squamous cell carcinoma was observed in the combined group, there was no significant variation in tumor development among the groups. The study indicated that the combination of NaNO(2) with AsA induces genotoxicity due to oxidative DNA damage in vitro, and elevates 8-OHdG levels in the forestomach epithelium, but lacks initiating activity in the rat two-stage carcinogenesis model.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antioxidants; Ascorbic Acid; Butylated Hydroxyanisole; Carcinogens; Cocarcinogenesis; Deoxyguanosine; Disease Models, Animal; DNA Damage; DNA, Bacterial; Drug Therapy, Combination; Escherichia coli; Gastric Mucosa; Male; Methylnitronitrosoguanidine; Mutagens; Organisms, Genetically Modified; Oxidation-Reduction; Oxidative Stress; Rats; Rats, Inbred F344; Sodium Nitrite; Stomach Neoplasms

Combined treatment with several phenolic antioxidants and sodium nitrite (NaNO(2)) has already shown to enhance rat forestomach carcinogenesis. In the present experiment, effects of green tea catechins (GTC) alone or in combination with NaNO(2) on gastric carcinogenesis were investigated in a rat two-stage carcinogenesis model. Groups of eight, 6-week-old F344 male rats were given 0.01%N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in their drinking water and 5% NaCl in the diet for 10 weeks for glandular stomach initiation and a single intragastric administration of 100 mg/kg/bodyweight of MNNG at week 9 for forestomach initiation. From week 11, they received either drinking water containing 0.2% NaNO(2) and a diet supplemented with 1% GTC in combination, each individual chemical alone or a basal diet until the end of week 42. In the forestomach, incidences and multiplicities of neoplastic lesions were clearly increased by the combined treatment, in spite of GTC alone suppressing the occurrence of papillomas. In a short-term experiment with similar protocol without MNNG pretreatment, a significant increase of 8-hydroxydeoxyguanosine (8-OHdG) levels in forestomach DNA occurred 24 h after the combined treatment, concomitant with erosion and inflammatory cell infiltration. In an in vitro study, electron spin resonance demonstrated hydroxyl radical formation after incubation of epigallocatechin gallate or epicatechin gallate with the NO generator, NOC-7. Thus, GTC alone showed a weak chemopreventive effect on forestomach carcinogenesis, but in the presence of NaNO(2) it exerted a promotive effect which might involve hydroxyl-radical-associated oxidative DNA damage. However, no influence was exerted in the glandular stomach.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Catechin; Deoxyguanosine; Disease Models, Animal; Epithelial Cells; Hyperplasia; Male; Methylnitronitrosoguanidine; Rats; Rats, Inbred F344; Stomach Neoplasms; Tea

Chemoprevention by dietary constituents has emerged as a novel approach to control stomach cancer incidence. We therefore evaluated the chemopreventive effects of black tea polyphenols (Polyphenon-B) on oxidant-antioxidant status, cell proliferation, apoptosis, and angiogenesis during N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinogenesis.. Male Wistar rats were divided into four groups. Rats in group 1 and 2 were given MNNG (150 mg/kg body weight) by intragastric intubation three times at 2 week intervals and followed for 26 weeks. Rats in group 2 received in addition a basal diet containing 0.05% Polyphenon-B. Group 3 animals were given 0.05% Polyphenon-B alone. Group 4 animals served as controls. The status of lipid peroxidation and antioxidants and the expression of the lipid peroxidation marker 4-hydroxy nonenal (4-HNE), proliferating cell nuclear antigen (PCNA), glutathiones-transferase (GST)-pi, Bcl-2, Bax, cytochrome C, caspase 3, cytokeratins, and vascular endothelial growth factor (VEGF) were used as biomarkers.. Intragastric administration of MNNG induced well-differentiated squamous cell carcinomas that showed diminished lipid and protein oxidation and an increase in antioxidant status. This was associated with increased cell proliferation, angiogenesis, and invasive potential coupled with apoptosis evasion as revealed by upregulation of PCNA, GST-pi, Bcl-2, cytokeratins, and VEGF and downregulation of Bax, cytochrome C, and caspase 3 protein expression. Dietary administration of Polyphenon-B effectively suppressed MNNG-induced gastric carcinogenesis, as evidenced by modulation of oxidant-antioxidant status, inhibition of cell proliferation and infiltration, and angiogenesis associated with apoptosis induction.. The present study provides evidence that Polyphenon-B exerts multifunctional inhibitory effects on MNNG-induced gastric carcinogenesis and suggests that it can be developed as a potential chemopreventive agent.

Topics: Aldehydes; Animals; Antioxidants; Apoptosis; Cell Proliferation; Chemoprevention; Disease Models, Animal; Down-Regulation; Immunohistochemistry; Lipid Peroxidation; Male; Methylnitronitrosoguanidine; Oxidants; Oxidation-Reduction; Phenols; Proliferating Cell Nuclear Antigen; Rats; Rats, Wistar; Stomach; Thiobarbituric Acid Reactive Substances; Up-Regulation

This study was designed to evaluate the chemopreventive effects of ethanolic Ocimum sanctum (OS) leaf extract on cell proliferation, apoptosis and angiogenesis during N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinogenesis.. The rats were divided into four groups of ten each. Rats in group one were given MNNG (150 mg/kg body weight) by intragastric intubation three times, with a two-week interval between treatments. Rats in group two were administered MNNG as in group one, and in addition, they received intragastric intubation of ethanolic OS extract (300 mg/kg body weight) three times per week, starting on the day following the first exposure to MNNG. The intubation of ethanolic OS extract continued until the end of the experimental period. Rats in group three were given ethanolic OS leaf extract only. Group four served as controls. All the rats were killed after an experimental period of 26 weeks.. Intragastric administration of MNNG-induced well-differentiated squamous cell carcinomas that showed increased cell proliferation, and angiogenesis with evasion of apoptosis, as revealed by the upregulation of proliferating cell nuclear antigen (PCNA), glutathione S-transferase-pi (GST-pi), Bcl-2, cytokeratin (CK) and vascular endothelial growth factor (VEGF) and with downregulation of Bax, cytochrome C and caspase 3 protein expression. Administration of ethanolic OS leaf extract reduced the incidence of MNNG-induced gastric carcinomas. This was accompanied by decreased expression of PCNA, GST-pi, Bcl-2, CK and VEGF, and overexpression of Bax, cytochrome C, and caspase 3.. This study provides evidence that, in MNNG-induced gastric carcinogenesis, the key proteins involved in the proliferation, invasion, angiogenesis and apoptosis, are viable molecular targets for chemoprevention using ethanolic OS leaf extract.

Topics: Animals; Anticarcinogenic Agents; Apoptosis; Carcinoma, Squamous Cell; Cell Proliferation; Chemoprevention; Disease Models, Animal; Male; Methylnitronitrosoguanidine; Neovascularization, Pathologic; Ocimum; Phytotherapy; Plant Extracts; Plant Leaves; Random Allocation; Rats; Rats, Wistar; Stomach Neoplasms; Vascular Endothelial Growth Factor A

Combination chemoprevention by diet-derived agents that induce apoptosis is a promising strategy to control gastric cancer, the second most common malignancy worldwide. The present study was undertaken to investigate the apoptosis-inducing potential of a combination of S-allylcysteine (SAC), an organosulphur constituent of garlic and lycopene, a tomato carotenoid during N-methyl-N'-nitro-N-nitroso-guanidine (MNNG) and saturated sodium chloride (S-NaCl)-induced gastric carcinogenesis in Wistar rats using the apoptosis-associated proteins Bcl-2, Bax, Bim, caspase 8 and caspase 3 as markers. Animals administered MNNG followed by S-NaCl developed squamous cell carcinomas of the stomach associated with increased Bcl-2 expression and decreased expression of Bax, Bim, caspase 8 and caspase 3. Although SAC and lycopene alone significantly suppressed the development of gastric cancer, administration of SAC and lycopene in combination was more effective in inhibiting MNNG-induced stomach tumours and modulating the expression of apoptosis-associated proteins. Our results suggest that induction of apoptosis by SAC and lycopene combination represents one of the possible mechanisms that could account for their synergistic chemopreventive activity against gastric cancer.

Topics: Analysis of Variance; Animals; Apoptosis; bcl-2-Associated X Protein; Biomarkers, Tumor; Blotting, Western; Carotenoids; Caspase 3; Caspases; Chemoprevention; Cysteine; Disease Models, Animal; Drug Therapy, Combination; Lycopene; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental; Probability; Proto-Oncogene Proteins c-bcl-2; Random Allocation; Rats; Rats, Wistar; Sensitivity and Specificity; Stomach Neoplasms

Chemoprevention by dietary constituents has emerged as a cost-effective approach to control the incidence of gastric cancer, the second most common malignancy worldwide, and a major cause of mortality in Chennai, India. Identification of dietary agents with chemopreventive potential requires prescreening in animal models. We evaluated the modifying effects of tomato paste against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced genetic damage and oxidative stress in male Swiss mice.. Quantitation of bone marrow micronuclei, extent of lipid peroxidation, and the status of the antioxidants reduced glutathione, glutathione peroxidase, and glutathione S-transferase in the stomach and liver of Swiss albino mice were used to monitor the protective effects of tomato. Three different doses of tomato (0.5, 1, and 2 g/kg of body weight) were administered intragastrically for 5 d consecutively followed by intragastric intubation of MNNG 1.5 h after the final administration.. Increased frequency of micronuclei and enhanced lipid peroxidation were accompanied by compromised antioxidant defenses in MNNG-treated rats. Pretreatment of tomato paste at the concentration of 1 and 2 g/kg of body weight significantly decreased micronuclei and lipid peroxidation and enhanced reduced glutathione-dependent antioxidant and detoxifying enzymes.. Our results demonstrate that tomato protects against the clastogenic effects of MNNG by decreasing micronucleated polychromatic erythrocytes and lipid peroxidation and enhancing antioxidant status.

Topics: Animals; Bone Marrow Cells; Chemoprevention; Disease Models, Animal; Dose-Response Relationship, Drug; Gastric Mucosa; Glutathione; Glutathione Peroxidase; Glutathione Transferase; Lipid Peroxidation; Liver; Male; Methylnitronitrosoguanidine; Mice; Micronucleus Tests; Mutagenicity Tests; Mutagens; Oxidative Stress; Plant Preparations; Solanum lycopersicum; Stomach

We investigated the chemopreventive effect of S-allylcysteine (SAC), a water-soluble garlic constituent against gastric carcinogenesis induced in male Wistar rats by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and saturated sodium chloride (S-NaCl). The animals were divided into four groups of six animals. Rats in groups 1 and 2 were administered MNNG (200 mg/kg body weight) on days 0 and 14 as well as S-NaCl (1 mL/rat) three days during weeks 0 to 3, and thereafter placed on basal diet until the end of the experiment. Rats in group 2 in addition received SAC (200 mg/kg body weight) three times per week starting on the day following the first exposure to MNNG and continued until the end of the experimental period. Group 3 animals were given SAC alone as in group 2. Group 4 animals received basal diet and tap water throughout the experiment and served as the untreated control. The animals were sacrificed after an experimental period of 21 weeks. Measurement of lipid peroxidation and antioxidants of the glutathione redox cycle in the stomach tissue, liver and venous blood was used to monitor the chemopreventive potential of SAC. All animals that received MNNG and S-NaCl alone, developed tumours, identified histologically as squamous cell carcinomas. In the tumour tissue, diminished lipid peroxidation was accompanied by increase in reduced glutathione (GSH) and GSH-dependent enzymes, whereas in the liver and circulation, enhanced lipid peroxidation was associated with antioxidant depletion. Administration of SAC suppressed the incidence of MNNG+S-NaCl-induced gastric tumours as revealed by the absence of carcinomas. SAC ameliorated MNNG-induced decreased susceptibility of the gastric mucosa to lipid peroxidation, whilst simultaneously increasing the antioxidant status. In the liver and blood, SAC reduced the extent of lipid peroxidation and significantly enhanced antioxidant activities. We suggest that SAC exerts its chemopreventive effects by modulating lipid peroxidation and enhancing GSH-dependent antioxidants in the target organ as well as in the liver and blood.

Topics: Animals; Antineoplastic Agents; Antioxidants; Biomarkers, Tumor; Carcinoma, Squamous Cell; Cysteine; Disease Models, Animal; Gastric Mucosa; Glutathione; Lipid Peroxidation; Liver; Male; Methylnitronitrosoguanidine; Oxidants; Oxidation-Reduction; Rats; Rats, Wistar; Sodium Chloride; Stomach Neoplasms

Effects of tamoxifen (TAM) on development of uterine endometrial carcinogenesis were studied in intact and ovariectomized (OVX) mice initiated with N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG). In experiment I, animals were implanted with cholesterol (ChL, controls) or TAM (5% w/w) and/or 17beta-oestradiol (E(2), 0.5% w/w) pellets s.c. from 9 to 25 weeks of age, until the termination of the experiment, and all received a single intra-uterine administration of ENNG (12.5 mg/kg) at 10 weeks of age. They were divided into four groups: ENNG + ChL (control), ENNG + TAM, ENNG + E(2) and ENNG + TAM + E(2). Endometrial proliferative lesions (hyperplasias and/or carcinomas) were observed in all groups, the incidences in the TAM- and/or E(2)-treated groups being two times higher than in the ChL-treated control animals. High induction (11/20, 55%) of adenocarcinomas was observed in the E(2) group but this was significantly decreased in combination with TAM (2/20, 10%), no carcinomas being found in the TAM group. In experiment II, animals pre-treated with TAM (10 weeks) and receiving E(2) post-treated (4 weeks) developed adenocarcinomas, although no cancers were observed in mice treated by ChL instead of TAM. In animals pre-treated with TAM and post-treated with ChL or TAM, no adenocarcinomas were also developed. In OVX mice (experiment III), proliferative lesions were observed in the TAM- and/or E(2)-treated groups, at incidences significantly higher than in ChL-treated animals, in which these lesions were completely absent. However, no adenocarcinomas were found, only slight hyperplasias being observed in the TAM group, although the incidence of adenocarcinoma was highest in the E(2) alone group, and significantly decreased in combination with TAM, as in experiment I. These results indicate that TAM may itself exert promotion effects, while exhibiting an anti-progression influence on uterine carcinogenesis in adult mice initiated by ENNG and receiving E(2).

Topics: Animals; Carcinogenicity Tests; Carcinogens; Disease Models, Animal; Drug Interactions; Endometrial Neoplasms; Female; Incidence; Methylnitronitrosoguanidine; Mice; Tamoxifen; Uterine Neoplasms

Human beings are exposed to a multitude of carcinogens in their environment, and most cancers are considered to be chemically induced. Here we examined differences in genetic alterations in rat forestomach tumors induced by repeated exposure to a genotoxic carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or N-methylnitrosourethane (MNUR), and chronic treatment with a non-genotoxic carcinogen, butylated hydroxyanisole (BHA) or caffeic acid (CA). A total of 132, 6-week-old male F344 rats were employed. Forty rats were treated with MNNG by intragastric administration at a dose of 20 mg/kg body wt once a week for 32 weeks, and 20 rats received 20 p.p.m. MNUR in their drinking water for 48 weeks. Further groups of 20 animals were administered 2% BHA or 2% CA in the diet for 104 weeks. The remaining rats were maintained without any supplement as controls. Multiple forestomach tumors were observed in all rats of the MNNG-, MNUR-, BHA- and CA-treated groups. Histopathologically, MNUR- and CA-treated groups showed almost the same pattern. On polymerase chain reaction-single strand conformation polymorphism analysis, H-ras and p53 gene mutations were observed at high and relatively low frequencies, respectively, in forestomach tumors induced by MNNG and MNUR. Most H-ras gene mutations were G-->A transitions in codons 7 and 12 of exon 1. On the other hand, forestomach tumors due to the non-genotoxic carcinogens, BHA and CA, had almost no mutations of the H-ras and p53 genes. Moreover, relative overexpression of cyclin D1 and p53 was detected in forestomach tumors induced by the genotoxic carcinogens, while their non-genotoxic counterparts had a tendency to show low expression of those molecules. Mutations of the beta-catenin gene were not detected in any group. The present study demonstrates that rat forestomach tumors induced by genotoxic and non-genotoxic carcinogens have different underlying genetic alterations, even if their pathological features are similar.

Topics: Animals; Base Sequence; Butylated Hydroxyanisole; Carcinogens; Disease Models, Animal; DNA Primers; Gene Expression Regulation, Neoplastic; Humans; Male; Methylnitronitrosoguanidine; Mutagens; Nitrosomethylurethane; Polymerase Chain Reaction; Polymorphism, Single-Stranded Conformational; Rats; Rats, Inbred F344; Stomach Neoplasms

N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG) treatments for a long period induced morphological and molecular alterations in the benign human colorectal polyps which were maintained in the severe combined immunodeficient C.B17/N-scid/scid mice. Thirty four xenografts of colorectal polyps from five solitary polyp and three familial polyposis patients were examined for K-ras and p53 mutations. Six K-ras mutations were induced in 16 grafts treated with MNNG more than five times, while no K-ras mutations were detected in 14 untreated grafts (P<0.05). Additional and new K-ras mutations were also induced in two polyps in which K-ras mutation had pre-existed. p53 mutations were not observed in both MNNG-treated and untreated groups. The mutations in K-ras gene were induced at codon 12 (GGT-->GAT) except one at codon 13 (GGC-->GGT). The results indicate that K-ras mutation plays an important role in human colorectal carcinogenesis as is the case in experimental animals.

Topics: Animals; Codon; Colonic Polyps; Colorectal Neoplasms; Disease Models, Animal; Genes, p53; Genes, ras; Humans; Methylnitronitrosoguanidine; Mice; Mice, SCID; Mutagenesis; Mutagens; Polymerase Chain Reaction; Polymorphism, Single-Stranded Conformational; Time Factors; Transplantation, Heterologous

Rat stomach cancers induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) are widely used as a model of differentiated-type human stomach cancers. ACI/NJcl (ACI) rats show persistent and strong cell proliferation in response to gastric mucosal damage by MNNG while BUF/NacJcl (BUF) rats show transient and limited cell proliferation. This difference is considered as one of the mechanisms for the high susceptibility of ACI rats to MNNG-induced stomach carcinogenesis. To identify genes involved in the differential induction of cell proliferation, cDNA subtraction was performed using RNA isolated from the pylorus of ACI and BUF rats treated with MNNG. By the temporal patterns of their expressions, the isolated 16 genes were overviewed and clustered into groups. Expression of the genes in group 1 (such as MHC class I and class II genes and interferon-inducible genes Iigp, Mx2 and Ubd) was induced by MNNG treatment, and the genes in group 2 (such as cellular retinoic acid-binding protein II (CrabpII)) were constantly expressed regardless of MNNG treatment. Then, expression profiles among multiple rat strains were compared with the extents of induction of cell proliferation. Iigp, CrabpII and EST222005 were found to show relatively good accordance, and these three genes were considered as candidates for genes that control differential induction of cell proliferation. Presence of polymorphisms at the genomic DNA level was indicated for CrabpII and EST222005, and these two genes were considered to be better candidates than IIGP: It was shown that the temporal profiles and profiles among strains, taking advantage of animal models, are useful to select candidate genes from a collection of genes isolated by various genome-wide scanning methods.

Topics: Animals; Base Sequence; Cell Division; Disease Models, Animal; DNA Primers; Gene Expression Profiling; Genes, MHC Class I; Genetic Predisposition to Disease; Methylnitronitrosoguanidine; Neoplasms, Experimental; Polymerase Chain Reaction; Polymorphism, Genetic; Pylorus; Rats; Rats, Inbred ACI; Rats, Inbred BUF; Rats, Inbred Strains; Receptors, Retinoic Acid; RNA; Species Specificity

The experiments presented here were done to evaluate whether the levels of CO2 in respiratory air during the 13C-bicarbonate breath test (13C-BBT) may be used as a marker of non-invasive diagnosis of the levels of atrophic gastritis. Twenty-eight patients with chronic gastritis and five healthy volunteers were enrolled in the study. Moreover, experimental gastritis was induced in rats by N-methy-N-nitro-N-nitrosoguanidine. In human, the levels of atrophic gastritis were evaluated from the vascular pattern of the gastric fornix. Total delta 13CO2 calculated from the 13C-BBT and the mucosal thickness ratio (MTR) were measured in rats with experimental gastritis. The levels of 13CO2 were significantly higher from patients with a vascular pattern at the fornix than in those without a vascular pattern (p<0.01). There was a good correlation between MTR and the levels of 13CO2, in rats with experimental gastritis (p<0.01). These findings indicate that the levels of 13CO2 during 13C-BBT reflect the levels of atrophic gastritis and show its clinical significance for non-invasive evaluation of atrophic gastritis. This has important clinical implications in selecting Helicobacter pylori-positive cases for therapy and follow-up.

Topics: Age Factors; Animals; Body Height; Body Weight; Breath Tests; Buffers; Carbon Dioxide; Carbon Isotopes; Disease Models, Animal; Gastric Mucosa; Gastritis, Atrophic; Humans; Male; Methylnitronitrosoguanidine; Rats; Rats, Wistar; Sex Factors; Sodium Bicarbonate

Helicobacter pylori infection is a risk factor for gastric cancer. How the bacterium contributes to this process is still unclear. We present a new Wistar rat model that was used to evaluate the effect of H. pylori on early preneoplastic events as judged from epithelial cell turnover and histopathological changes. One hundred and four rats were colonized with H. pylori and exposed MNNG (N-methyl-N'-nitro-N'-nitrosoguanidine) and/or taurocholic acid. Inflammation, goblet cell-like metaplasia, atrophy, dysplasia, and adenocarcinoma were scored in a blinded manner. Apoptotic cells were counted after staining with terminal uridine deoxynucleotidyl nick end labeling, and epithelial cell proliferation was determined by means of the Ki-67 labeling index. No early tumor enhancement with H. pylori could be found in ordinary histology. However, H. pylori significantly enhanced the epithelial cell proliferation compared with the control group, and the combination with taurocholic acid appeared to have a synergistic effect. MNNG significantly increased the normal gastric epithelial apoptosis. This increase was reduced in antral mucosa with H. pylori infection. The findings suggest that H. pylori, especially when combined with bile. has an influence on cell kinetics, contributing to the development of gastric cancer. The reduced apoptosis of MNNG also observed in infected animals indicates a dual function of H. pylori.

Topics: Adenocarcinoma; Animals; Apoptosis; Carcinogens; Disease Models, Animal; Gastric Mucosa; Helicobacter Infections; Helicobacter pylori; Immunohistochemistry; In Situ Nick-End Labeling; Ki-67 Antigen; Kinetics; Male; Methylnitronitrosoguanidine; Rats; Rats, Wistar; Stomach Neoplasms; Taurocholic Acid

The aim of this study was to evaluate the early influence of Helicobacter pylori infection on cell kinetics in the antral mucosa of mice exposed to N-methyl-N'-nitro-N'-nitrosoguanidine (MNNG) and bile alone or in combinations. Four hundred and one C57BL/6 male and female mice were assigned into seven treatment groups and one non-treated control group. The gastric antrums were assessed by histology and immunohistochemistry for studies of cell proliferation and apoptosis at 32 and 44 weeks. One female and one male mouse had developed dysplastic adenomas in the pylorus mucosa and one male animal had dysplastic proliferation in the antrum. Only one of these lesions occurred in a H. pylori colonized animal. H. pylori infection significantly increased the cell proliferation at 32 weeks and promoted the cell proliferation in the MNNG and bile group at 44 weeks. Female mice showed less increase in cell proliferation than did the males. No change in apoptosis was seen in any of the groups. Bile had no promotional effect on cell proliferation. These results indicate that H. pylori infection has the potential to alter epithelial cell kinetics as well as antrum mucosa of an animal species that is regarded as resistant to MNNG. However, this change is not sufficient to promote the early development of neoplastic lesions.

Topics: Adenoma; Animals; Apoptosis; Carcinogens; Disease Models, Animal; Epithelium; Female; Gastric Mucosa; Helicobacter Infections; Helicobacter pylori; Immunohistochemistry; In Situ Nick-End Labeling; Ki-67 Antigen; Kinetics; Male; Methylnitronitrosoguanidine; Mice; Mice, Inbred C57BL; Pyloric Antrum; Stomach Neoplasms; Taurocholic Acid

Rat stomach cancers induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) have been widely used as a model for human stomach cancers of the differentiated type. However, there has been little information regarding their molecular basis. In this study, we examined the genetic alterations reported in human stomach cancers in 10 rat stomach cancers that had been induced in male ACI/N rats by administering MNNG in the drinking water. One of the 10 cancers had a mutation of the p53 gene at the second position of codon 171 (Val --> Glu). However, none of the 10 cancers had mutations in codons 12, 13, or 61 of Ki-ras or in the N-terminal phosphorylation sites of the beta-catenin gene. Southern blot analysis showed no amplification of K-sam or c-erbB-2 in the seven cancers examined. Finally, we searched for microsatellite alterations in 12 loci in nine cancers, but no alterations were observed. As these genetic alterations are observed in only a minor fraction of human stomach cancers, further analysis of genetic and epigenetic alterations in MNNG-induced rat stomach cancers is needed to disclose the major mechanisms of stomach carcinogenesis.

Topics: Animals; beta Catenin; Blotting, Southern; Codon; Cytoskeletal Proteins; Disease Models, Animal; DNA Mutational Analysis; Exons; Gene Amplification; Genes, erbB-2; Genes, p53; Genes, ras; Male; Methylnitronitrosoguanidine; Microsatellite Repeats; Mutation; Phosphorylation; Polymorphism, Single-Stranded Conformational; Rats; Rats, Inbred ACI; Receptor Protein-Tyrosine Kinases; Receptor, Fibroblast Growth Factor, Type 2; Receptors, Fibroblast Growth Factor; Stomach Neoplasms; Trans-Activators

In 1994 WHO/IARC concluded that "Helicobacter pylori is a definite carcinogen" based on epidemiological studies, but there have been few reports demonstrating a relation between H. pylori and stomach cancer in animal models. We have succeeded in producing adenocarcinomas in the glandular stomachs of Mongolian gerbils with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or N-methyl-N-nitrosourea as carcinogens and hope to establish an experimental stomach carcinogenesis model using H. pylori. Male Mongolian gerbils, 7 weeks old, were infected with H. pylori followed by MNNG administration at a concentration of 100ppm administration or treated with MNNG at a concentration of 300ppm in their drinking water followed by inoculation with H. pylori. They were then killed sequentially, and their excised stomachs underwent microbiological and histopathological examinations. H. pylori were detected in all infected gerbils. Hyperplastic change of pyloric mucosa was observed with high 5-bromo-2'-deoxyuridine incorporation in affected animals. H. pylori infection persists on administration of MMNG and enhances glandular stomach proliferation in Mongolian gerbils. Whether long-term colonization promotes carcinogenesis in the glandular stomach of Mongolian gerbils is a matter of great interest.

Topics: Adenocarcinoma; Animals; Carcinogens; Colony Count, Microbial; Disease Models, Animal; Gerbillinae; Helicobacter Infections; Helicobacter pylori; Immunohistochemistry; Male; Methylnitronitrosoguanidine; Specific Pathogen-Free Organisms; Stomach Neoplasms

An animal model of stomach carcinogenesis was established using Mongolian gerbils with N-methyl-N-nitrosourea (MNU) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) as the carcinogens. In addition, the sensitivity of these gerbils to Helicobacter pylori (H. pylori) was confirmed. One hundred and sixty specific pathogen-free male MGS/Sea animals, 7 weeks old, were treated with MNU in the drinking water (30 ppm for alternate weeks to give 10 weeks exposure, or 10 ppm or 3 ppm for 20 weeks continuous exposure), or given MNNG in the drinking water at 400 ppm or 200 ppm for 20 weeks, or orally inoculated with ATCC43504 H. pylori (1.7 x 10(8) CFUs/animal). Adenocarcinomas in the glandular stomach were found in 2 out of 12 effective animals (2/ 12) treated with 30 ppm MNU at week 20, although all were dead or moribund by week 30 due to MNU toxicity. At week 50, the incidences of gastric adenocarcinomas in groups treated with 10 ppm MNU, 3 ppm MNU, 400 ppm MNNG, and 200 ppm MNNG were 2/21 (9.5%), 1/23 (4.3%), 7/ 11 (63.6%), and 1/10 (10.0%). The lesions were generally well differentiated, although poorly differentiated adenocarcinoma was also found in a single gerbil in each of the 10 ppm MNU and 400 ppm MNNG groups. In control animals no tumors were found. In the infection study, the animals were killed at week 20, and H. pylori was detected in all cases, causing multiple erosions with marked inflammatory cell infiltration in the lamina propria and submucosa, and frequent formation of lymphoid follicles. Thus, MNU and MNNG in the drinking water induced neoplastic lesions in the glandular stomach epithelium of H. pylori-sensitive gerbils.

Topics: Adenocarcinoma; Administration, Oral; Animals; Carcinogens; Cocarcinogenesis; Disease Models, Animal; Disease Susceptibility; Drinking; Gerbillinae; Helicobacter Infections; Helicobacter pylori; Male; Methylnitronitrosoguanidine; Methylnitrosourea; Stomach Neoplasms; Water

Rebamipide is a potent antioxidative agent; it increases gastric mucosal PGE2 production and thus protects the gastric mucosa. We hypothesized that the mechanisms of ulcer formation could be extended to carcinogenesis and that an increase in gastric mucosal protection may result in a decrease in gastric carcinogenesis. Therefore, we assessed the inhibitory effects of rebamipide on N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) -induced carcinogenesis in mice. The percentage of tumor-bearing mice in three treatment groups--ENNG + rebamipide 20 mg, ENNG + rebamipide 50 mg, and ENNG alone--was 55%, 42%, and 67%, respectively. The incidence of tumorigenesis tended to decrease with increasing doses of rebamipide. The difference between ENNG + rebamipide 50 mg and ENNG alone was statistically significant (P < 0.05). These results suggest that rebamipide may strengthen the host defense mechanisms related to carcinogenesis in the digestive tract.

Topics: Alanine; Animals; Antineoplastic Agents; Carcinogens; Disease Models, Animal; Dose-Response Relationship, Drug; Duodenal Neoplasms; Male; Methylnitronitrosoguanidine; Mice; Mice, Inbred C57BL; Quinolones

The aim of this study was to determine whether gastric epithelial proliferation due to gastric Helicobacter infection in mice represents a preneoplastic lesion.. Helicobacter heilmannii infected and uninfected mice were treated with 150 microg/ml N-methyl-N'-nitro-N-nitrosoguanidine in drinking water for either 20 or 38 weeks. Mice were killed 12 or 18 months after bacterial inoculation.. All infected mice developed lymphoplasmocytic gastritis and epithelial hyperplasia. Proliferative gastric lesions were characterised by nodular hypertrophy of the glandular mucosa, multifocal epithelial hyperplasia, and elevated BrdU labeling index. Intestinal metaplasia and true atrophy were not present but proliferative glands were poorly differentiated, lined by mucus-type epithelial cells with no parietal, chief or other specialized cell types. Neoplasms developed only in MNNG-treated mice. of the 180 treated mice the following neoplasms developed: 14 squamous cell carcinomas of mouth and forestomach; 37 hemangiosarcomas of the intestinal serosa; and 15 splenic lymphomas. No tumors were present in the glandular gastric mucosa, and infection did not affect tumor incidence. p53 overexpression occurred in 79% of hemangiosarcomas and 71% of squamous cell carcinomas but not in normal or proliferative gastric glandular mucosa.. Gastric proliferative lesions in Helicobacter-infected mice are not preneoplastic, and the combination of an alkylating agent and non-neoplastic proliferation does not result in gastric carcinogenesis in mice.

Topics: Animals; Bromodeoxyuridine; Carcinogens; Disease Models, Animal; Female; Gastric Mucosa; Gastritis; Gene Expression Regulation, Neoplastic; Genes, p53; Helicobacter; Helicobacter Infections; Methylnitronitrosoguanidine; Mice; Mice, Inbred BALB C; Neoplasms, Experimental; Stomach Neoplasms

Current experimental models of pancreatic cancer either fail to reproduce the ductal phenotype or cause simultaneous cancers in other organs also. To develop an animal of pancreatic cancer that accurately mimics the human condition, we restricted carcinogenic exposure to the pancreas and specifically targeted ductal epithelial cells. Three different carcinogens were either implanted directly into the pancreas or infused into the pancreatic duct, with or without near-total pancreatectomy (as a means of inducing pancreatic ductal cell proliferation).. Groups of male Sprague-Dawley rats were exposed to varying doses of dimethylbenzanthracine (DMBA), methynitronitrosoguanidine, or ethylnitronitrosoguanidine either through direct implantation into the pancreas or infusion into the pancreatic duct. Near-total pancreatectomy was added in all groups except two DMBA implantation groups. Surviving rats were killed at 3, 6, 9, or 12 months, and the pancreata were evaluated histologically.. All three carcinogens caused pancreatic inflammation, ductal hyperplasia, atypia, and dysplasia beginning by 3 months and becoming more prominent at later time points. Only DMBA caused frequent invasive pancreatic ductal adenocarcinoma, which was first evident by 6 months. The prevalence of pancreatic cancer among DMBA-treated rats evaluated after 10 months was 39% (19 of 49). The addition of pancreatic resection did not enhance pancreatic cancer development.. Of the strategies tested, only direct implantation of DMBA into the rat pancreas frequently produces pancreatic cancer histologically similar to human ductal adenocarcinoma. The development of hyperplastic, atypical, and dysplastic changes preceding and accompanying carcinomas suggests that these lesions are preneoplastic. This model recapitulates the progression from normal to neoplastic epithelium and is likely to be useful for the study of morphologic and molecular mechanisms underlying the early stages of pancreatic carcinogenesis and for the investigation of novel diagnostic and therapeutic techniques.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinogens; Carcinoma, Ductal, Breast; Disease Models, Animal; Fibrosarcoma; Hyperplasia; Male; Methylnitronitrosoguanidine; Pancreatectomy; Pancreatic Ducts; Pancreatic Neoplasms; Rats; Rats, Sprague-Dawley; Sarcoma, Experimental

Sequential endoscopic observation of dog colons was performed during colon carcinogenesis. Two beagle dogs were given suppositories containing N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) every day for five months. In month 3, aberrant crypt foci (ACF), a putative preneoplastic lesion, were found in the colons of both dogs, but not in an untreated dog. The frequency of ACF increased until month 10, and then decreased. In month 9, very small lesions, less than 1 mm in diameter, which were similar to human early flat tumors, were first noticed. One of these lesions grew to about 7 mm in size without a change in its shape for 10 months. There were more than ten flat-type tumors in the two dogs, but such lesions were not found in the untreated dog. By biopsy, two of the lesions were proved to be well-differentiated adenocarcinomas histologically. Four polypoid lesions were found in one of the carcinogen-treated dogs. Thus, flat-type adenocarcinomas were induced in the dog colon by ENNG, and their development was followed by magnifying endoscopy.

Topics: Adenocarcinoma; Animals; Carcinogens; Colon; Colonic Neoplasms; Colonic Polyps; Disease Models, Animal; Dog Diseases; Dogs; Endoscopy; Methylnitronitrosoguanidine; Precancerous Conditions

The effect of ethanol (EtOH) on esophageal cell proliferation and the development of esophageal cancers induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in shrews were investigated. Sequential histological examination was done, and cell proliferation was assessed by BrdU labeling. At 5 weeks of age, animals were given tap water, 2% EtOH, 50 ppm MNNG, or 50 ppm MNNG plus 2%, 5% or 10% EtOH in the drinking water. Administration of 10% and 5% EtOH simultaneously with MNNG caused death in 40% (10/25) within 4 days and in 20% (6/30) within 7 days respectively, whereas other treatment were well tolerated with no sudden deaths. Administration of 2% EtOH for 30 weeks caused a 2-fold increase, and that of MNNG caused a 4.5-fold increase in the proliferation index of the basal cells of the esophagus compared with control shrews, and MNNG plus 2% EtOH caused a 5.5-fold increase. In MNNG-treated shrews, with or without 2% EtOH administration, sequential histological examination of esophageal tissue revealed a similar change; dysplasia appeared at 30 weeks of age, squamous cell carcinoma occurred at 35 weeks of age, and the depth of invasion extended to adventitia at 45 weeks of age. These finding indicate that treatment with 2% EtOH promoted the proliferation of esophageal basal cells but did not alter the tumor induction period and did not have tumor-promoting activity. EtOH per se was not carcinogenic; no tumors were seen in shrews not administered MNNG.

Topics: Animals; Carcinogens; Cell Division; Cocarcinogenesis; Disease Models, Animal; Esophageal Neoplasms; Esophagus; Ethanol; Female; Methylnitronitrosoguanidine; Shrews

The purpose of this study was to develop a model of gastrointestinal carcinogenesis using C57BL/6 mice. Treatment regimens consisted of one control group and 2 groups which received N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in drinking water: 50 micrograms/ml x 52 weeks and 100 micrograms/ml x 27 weeks. In addition, 2 protocols using adjuvant agents intended to increase tumor formation were used: MNNG (100 micrograms/ml) x 27 weeks + 0.2% taurocholic acid added to the diet from weeks 13-52, and MNNG (50 micrograms/ml) x 33 weeks+caerulein (10 micrograms/kg) subcutaneously 3 times/week from weeks 21-52. High-grade dysplasia was observed in the duodenum of 1/13 mice treated with MNNG (50 micrograms/ml). The combination of the latter and caerulein did not augment tumorigenesis. Mice treated with MNNG (100 micrograms/ml) frequently developed neoplasia in the duodenum and upper jejunum. Foci of low-grade and high-grade dysplasia alone were found in 3/12 (25%) mice; and intramucosal and invasive adenocarcinoma were found in 7/12 (58.3%) mice. The addition of taurocholic acid significantly increased the number and histological stages of the tumors (adenocarcinoma occurred in 100%, P = 0.03) and decreased the time for tumor formation.

Topics: Adenocarcinoma; Administration, Oral; Animals; Ceruletide; Disease Models, Animal; Drug Synergism; Female; Gastrointestinal Neoplasms; Methylnitronitrosoguanidine; Mice; Mice, Inbred C57BL; Taurocholic Acid

The aim of the present investigation was to evaluate abnormal changes in trace element concentrations during carcinogenesis. First, Al, Zn and Cu in the liver tissues of rats were measured by atomic absorption analysis over a half year of hepatocarcinogenesis. Male Wistar rats were given carcinogenic food containing 600 mg/kg of 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB) in a basal diet for several months. After 4 to 6 months of feeding, hepatocarcinomas developed in the rats. Zn and Cu concentrations in the hepatocarcinomas of the 3'-MeDAB group significantly decreased as compared with normal liver tissues of the control groups. On the other hand, the aluminum concentration in the hepatocarcinomas was more than three times that in the normal liver tissues. The Al and Se contents of developed gastric and mammary cancers were measured in Experiment II. Male and female rats were given 1-methyl-3-nitrothoguanidine(MNNG) and 2,7-dimehtylbenz(a)anthracene(DMBA), respectively. After several months, carcinomas developed in over half of the rats. The Al and Se concentrations in cancers, livers and the blood were determined by atomic absorption analysis. It was shown that both gastric and mammary carcinomas contained a high level of aluminum and very little selenium in comparison with normal liver tissues. The present study demonstrated that aluminum accumulated in experimentally induced carcinomas in rats, i.e., cancers of the liver, stomach, duodenum and mammary glands.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Aluminum; Animals; Carcinoma, Hepatocellular; Copper; Disease Models, Animal; Duodenal Neoplasms; Female; Liver Neoplasms; Male; Mammary Neoplasms, Experimental; Methyldimethylaminoazobenzene; Methylnitronitrosoguanidine; Rats; Rats, Sprague-Dawley; Rats, Wistar; Reference Standards; Spectrophotometry, Atomic; Stomach Neoplasms; Zinc

The histological changes occurring in the esophageal mucosa of shrews (Suncus murinus) after N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) treatment were investigated sequentially. Six-week-old female shrews were given a 50 micrograms/ml MNNG solution as drinking water for 30 weeks, and 5 selected at random were killed at 10 and 20 weeks of age, and thereafter at 5-week intervals until 45 weeks of age. Controls were killed at 45 weeks of age. The MNNG-induced esophageal lesion in shrews began from basal cell hyperplasia at 20 weeks of age, followed by dysplasia occurring at 25 weeks of age, then progressed toward intraepithelial carcinoma to invasive squamous cell carcinoma at 35 weeks of age. Apparent sequential dysplasia-carcinoma transition was seen. Papillomas were seen from 25 weeks of age but there was no evidence of papilloma-carcinoma sequence. Five MNNG-untreated shrews killed at the end of the experiment were free of esophageal tumors.

Topics: Animals; Carcinoma in Situ; Carcinoma, Squamous Cell; Cell Transformation, Neoplastic; Disease Models, Animal; Esophageal Neoplasms; Female; Immunoenzyme Techniques; Methylnitronitrosoguanidine; Papilloma; Shrews

Adenocarcinoma, adenoma and dysplasia of the stomach of adult Wistar rats were induced following administration of MNNG for 10 days by gavage when they were new-born. The incidence of the three types of pathological lesions at the dose of 0.4 mg MNNG per rat being 39%, 50% and 100% respectively. Induction of gastric adenocarcinoma is dose-dependent. The incidence of adenocarcinoma in male rats being significantly higher then that of female rats (P < 0.02). 23 of 33 (70%) induced cancers were found in the gastric antrum. By the use of DNA cotransfection technique and the assay of carcinogenicity in the Balb/c nude mice, it was also found that the DNA of 4 of the 6 induced gastric carcinomas could transform NIH/3T3 cells into malignant cells, an indication that the induced cancer DNA contains transforming gene.

Topics: 3T3 Cells; Adenocarcinoma; Animals; Animals, Newborn; Cell Transformation, Neoplastic; Disease Models, Animal; DNA, Neoplasm; Female; Male; Methylnitronitrosoguanidine; Mice; Mice, Inbred BALB C; Mice, Nude; Rats; Rats, Wistar; Stomach Neoplasms; Transfection

N-Methyl-N-nitro-N'-nitrosoguanidine (MNNG) is a gastric carcinogen in several animal species and has been used in a number of systems to dissect the co-carcinogenic potential of various compounds in the induction of gastric adenocarcinoma. Recent epidemiological evidence suggests that Helicobacter pylori may play a role as a co-carcinogen in the etiology of this tumor in humans and we have been interested in developing an animal model to study this possibility. A related organism, H. mustelae, naturally colonizes the ferret stomach and causes persistent chronic gastritis. The pathology elicited by H. mustelae in ferrets has many similarities with the human disease including different stages of multifocal atrophic gastritis which underlie the gastric ulcer and gastric carcinoma syndrome. There is little evidence, however, demonstrating the susceptibility of ferrets toward chemical carcinogenesis. We have consequently undertaken a study to ascertain whether 10 6-month-old female ferrets given a single oral dose of MNNG (50-100 mg/kg) would develop adenocarcinoma of the stomach. Five age-matched unmanipulated control animals were included for comparative purposes. All 15 ferrets were infected with H. mustelae. Nine of 10 ferrets dosed with MNNG developed gastric adenocarcinoma (29-55 months after dosing), while none of the five historical control ferrets examined an average of 63 months after the initiation of the study developed gastric tumors. By comparison, we have not observed gastric adenocarcinoma, nor has it been reported, in > 10 years of observation of untreated ferrets naturally infected with H. mustelae. The H. mustelae-infected ferret, with demonstrated susceptibility to a gastric carcinogen, plus the recent availability of specific pathogen-free ferrets, should now allow longitudinal studies in vivo to probe the role of Helicobacter in the development of gastric cancer.

Topics: Adenocarcinoma; Animals; Biopsy; Cocarcinogenesis; Disease Models, Animal; Female; Ferrets; Gastritis; Helicobacter Infections; Longitudinal Studies; Methylnitronitrosoguanidine; Pyloric Antrum; Stomach; Stomach Neoplasms

Female 6-week-old shrews were given a solution of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) at a concentration of 50 micrograms/ml or 100 micrograms/ml in the drinking water. All 11 shrews receiving 100 micrograms/ml MNNG died 8-13 days after the beginning of carcinogen administration and 6 of the 20 shrews receiving 50 micrograms/ml MNNG died after 10-54 days. When animals were between 43 and 54 weeks of age, multiple esophageal lesions were evoked in all 14 that had received 50 micrograms/ml MNNG for 30 weeks. All shrews developed a protruding, ulcerative, or superficial type of squamous-cell carcinoma of the esophagus, accompanied by papillomas. Local invasion was seen in squamous-cell carcinoma but no distant metastasis was noted. None of the 5 control shrews developed any esophageal abnormality. No gastric adenocarcinoma, intestinal sarcoma, or other tumors were induced with MNNG. It can be concluded that MNNG has a carcinogenic effect on shrew esophageal epithelium.

Topics: Animals; Carcinoma, Squamous Cell; Disease Models, Animal; Esophageal Neoplasms; Female; Methylnitronitrosoguanidine; Papilloma; Shrews

The development of carcinoma was examined in male Wistar rats (n = 120) exposed to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in the drinking water (83 micrograms/ml) for 16 weeks. After MNNG administration, rats were investigated by endoscopic observation, visualization of microvascular structure, and estimation of lectin binding sites. Changes of bile reflux to the stomach was observed endoscopically at 24 weeks as well as the development of gastric mucosal erosions. Protruding and expansive ulcerating carcinomas developed at 36 weeks and had a microvascular pattern similar to that of human adenocarcinoma. Estimation of lectin binding site and pattern was useful to evaluate the malignant potential of cell proliferation. We postulate that endoscopic observation is valuable in investigating the development of gastric carcinoma, and microvascular structure and lectin binding pattern may be useful to demonstrate the mechanism of growth of gastric carcinoma.

Topics: Animals; Binding Sites; Cell Transformation, Neoplastic; Disease Models, Animal; Gastric Mucosa; Lectins; Male; Methylnitronitrosoguanidine; Protein Binding; Rats; Rats, Inbred Strains; Stomach Neoplasms

It may be useful to study the incipient phase and growth behavior of pancreatic cancer if experimental pancreatic carcinoma can be produced in dogs. Twelve mongrel dogs were used. Pancreatography was done every month. N-nitrosobis (2-oxopropyl) amine (BOP) was administered through the drainage tube inserted into the dorsal pancreatic duct in 4 dogs. Macroscopically, atrophy of the pancreas was recognized, but microscopically, no tumors were observed. BOP was injected intraperitoneally in 2 dogs. No tumors were found, and the hepatic necrosis was detected in one dog. N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) was administered into the dorsal pancreatic duct in 2 dogs. Macroscopically, atrophy of the pancreas was recognized, but microscopically, no tumors were observed. ENNG was administered through the drainage tube inserted into the tail portion in 4 dogs. In one dog received a total dose of 595mg of ENNG, duct obstruction was detected by pancreatography and duct adenocarcinoma microscopically was found. Papillary hyperplasia of the epithelium of pancreatic duct was observed in all others. Pancreatic duct adenocarcinoma and papillary hyperplasia were successfully produced in dogs by intraductal administration of ENNG through the pancreatic tail portion. This method seems to be useful for producing experimental pancreatic cancer.

Topics: Adenocarcinoma; Animals; Disease Models, Animal; Dogs; Female; Male; Methylnitronitrosoguanidine; Nitrosamines; Pancreatic Ducts; Pancreatic Neoplasms

The experiments reported here describe the derivation of an immunogenic melanoma cell line from B16 melanoma by sequential in vitro mutagenization with two chemical mutagens: n-methyl n-nitro n-nitrosoguanine (MNNG) and ethane methyl sulfonate (EMS). Following in vivo screening of over 100 mutant melanoma clones, a single clone was selected for further study. When transplanted to the anterior segment of the mouse eye, the mutant melanoma (D5.1G4) underwent spontaneous resolution in 20% of the immunologically intact hosts. Tumor rejection involved extensive necrosis and culminated in phthisis of the tumor-containing eye. Histologic analysis revealed a prominent mononuclear cellular infiltrate in contrast to the parental progressor B16 melanoma. Immunologic analysis of tumor-bearing hosts showed variable cytotoxic T lymphocyte (CTL) responses but potent delayed-type hypersensitivity (DTH) responses directed against the melanoma cells. Fluorescent activated cell sorter (FACS) analysis of tumor-infiltrating cells from ocular tumors revealed a cellular response consisting mainly of CD8+ CTLs and macrophages. Cultured D5.1G4 melanoma cells demonstrated: 1) enhanced expression of class I major histocompatibility complex (MHC) antigens; 2) increased susceptibility to CTL-mediated killing; and 3) increased susceptibility to tumor necrosis factor (TNF)-mediated cytolysis. Therefore, the intraocular D5.1G4 mutant melanoma model provides important insights into the immunology and immunopathology of intraocular tumor rejection. More intensive analysis of this intraocular melanoma may yield strategies for directing the immune response toward tumor rejection while minimizing damage to normal ocular components.

Topics: Animals; Anterior Eye Segment; Cell Separation; Disease Models, Animal; Eye Neoplasms; Female; Flow Cytometry; Histocompatibility Antigens Class I; Hypersensitivity, Delayed; Killer Cells, Natural; Melanoma, Experimental; Mesylates; Methylnitronitrosoguanidine; Mice; Mice, Inbred C57BL; Mutation; Neoplasm Regression, Spontaneous; Neoplasm Transplantation; T-Lymphocytes, Cytotoxic; T-Lymphocytes, Regulatory; Tumor Cells, Cultured

In a series of extensive studies on gastric carcinogenesis, we have used Sprague-Dawley rats to examine the morphologic, histochemical, and biochemical effects of risk and protective factors on N-methyl-N'-nitro-N-nitroso guanidine (MNNG)-induced tumors in an attempt to link early observations with the end-point lesion, gastric cancer. We have observed that the putative risk factors sodium chloride (NaCl); a mixture of bile acids; aspirin; alcohol; and nitrite enhance MNNG-induced neoplasia of the gastric mucosa. On the other hand butylated hydroxyanisol (BHA), Se and difluromethylornithine (DFMO) were protective and inhibited the induction of gastric mucosal neoplasia. In most cases, early changes detected by a number of criteria correlated with the end-point, gastric neoplasia. This model appears to be useful in screening and evaluating chemicals for risk for or protection against gastric cancer.

Topics: Animals; Bile Acids and Salts; Disease Models, Animal; Eflornithine; Gastric Mucosa; Male; Methylnitronitrosoguanidine; Rats; Rats, Inbred Strains; Risk Factors; Sodium Chloride; Stomach Neoplasms; Sulfhydryl Compounds

Topics: Adenocarcinoma, Mucinous; Animals; Disease Models, Animal; Dogs; Female; Gastric Mucosa; Male; Metaplasia; Methylnitronitrosoguanidine; Stomach Neoplasms

Chemically induced (autochthonous) tumors in the rodent are thought to be the best models at hand to obtain results transferable to the clinical situation. Four different autochthonous tumor models: 1,2-dimethylhydrazine, N-methylnitrosourea (MNU), N-methyl-N-nitro-nitrosoguanidine (MNNG), and N-nitroso-acetoxymethyl-methylamine (AMMN) which are used worldwide for etiological and therapy studies of colon cancer are compared for tumor biology and clinical relevance. The four tumor models of colon carcinoma described in the rat are different in growth, invasion, and metastases. The choice of the selected tumor model for experimental investigations of colon cancer should depend on the clinical question.

Topics: 1,2-Dimethylhydrazine; Adenocarcinoma; Animals; Colonic Neoplasms; Dimethylhydrazines; Dimethylnitrosamine; Disease Models, Animal; Methylnitronitrosoguanidine; Methylnitrosourea; Rats; Rectal Neoplasms

Topics: Animals; Disease Models, Animal; Gastric Juice; Gastric Mucosa; Gastritis; Gastritis, Atrophic; Male; Methylnitronitrosoguanidine; Parietal Cells, Gastric; Rats; Taurocholic Acid

The aim of this report is to prove that cancer tissue is to be eradicated by Nd:YAG laser irradiation and to show the process of its eradication using MNNG induced gastric cancers in rats as a material. Material and Method; in male rats of Wister strain, gastric cancers were induced by 30 weeks administration of 80 mg/1 MNNG solution. Then tumor bearing rats underwent laparotomy and gastrotomy, and tumors were irradiated by the Nd:YAG laser with 30W at the distance of 1cm, total energy ranging 120-1800 joules. These 20 stomachs were examined histologically; 10 of them within 14 days, the rest more than 4 weeks after the irradiation.

Topics: Adenocarcinoma; Animals; Disease Models, Animal; Gastroscopy; Laser Therapy; Male; Methods; Methylnitronitrosoguanidine; Rats; Rats, Inbred Strains; Stomach Neoplasms

Juvenile medaka were exposed to N-methyl-N'-nitro-N-nitrosoguanidine in water under static renewal conditions for 28 days. Two groups of 134 fish each were pulsed 3 times weekly at nominal concentrations of 1.0 and 0.5 mg/liter with N-methyl-N'-nitro-N-nitrosoguanidine dissolved in dimethylformamide. A third group of 134 fish was exposed to the solvent control, 0.01% dimethylformamide in water. Following the 28-day exposure, and during the recovery period, fish were sampled at intervals of approximately 0, 3, 6, and 9 months and examined grossly. Selected tissues were evaluated microscopically. Many tumor types developed in both N-methyl-N'-nitro-N-nitrosoguanidine exposure groups, but only the gill lesions will be discussed. Approximately 50% of the fish in both treatment groups died from gill damage in the second to third month of the recovery period. More than 90% of the surviving treated fish displayed gill lesions, which progressed from mild epithelial hyperplasia of gill filaments at 0-months recovery to epitheliomatous hyperplasia at 3 months and advanced to a more focal nodular appearance of gill filaments at 6 months. Eight to 9 months after the treatment period, at least four fish displayed branchial blastomas. The control fish had no gill lesions. Chemically induced gill tumors have not been previously observed in fish. Even gill tumors of unknown origin are very rare.

Topics: Animals; Disease Models, Animal; Fish Diseases; Fishes; Gills; Hyperplasia; Methylnitronitrosoguanidine; Neoplasms; Time Factors

A series of experiments was devised to determine possible modifying effects of stress, aspirin, and sodium taurocholate on the activity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in the Buffalo rat stomach. MNNG is a well known, direct-reacting carcinogen, and has been a reliable agent for the experimental production of gastric adenocarcinoma. The authors were able to produce adenocarcinomas in rats, but found a great number of gastric leiomyosarcomas. These occurred only in the groups given MNNG in combination with stress, aspirin, or sodium taurocholate, and did not occur in experimental groups given either MNNG, stress, aspirin, or sodium taurocholate alone, and did not occur in the control group.

Topics: Adenocarcinoma; Animals; Aspirin; Cocarcinogenesis; Diet; Disease Models, Animal; Leiomyosarcoma; Male; Methylnitronitrosoguanidine; Rats; Rats, Inbred BUF; Stomach Neoplasms; Stress, Physiological; Taurocholic Acid

We prepared a suppository containing 50 mg of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG), and successfully produced experimental colon cancer with good reproducibility by continuous intrarectal insertion of one or two suppositories per day in dogs. The tumors were very similar to human colon cancers, macroscopically and histologically. In one of three dogs subjected to histopathological study, metastases to the lymph nodes, lung, liver and kidney were observed. This animal model produced by a simple procedure will be helpful in investigating treatment of rectal cancer.

Topics: Adenocarcinoma; Animals; Carcinoma; Colonic Neoplasms; Disease Models, Animal; Dogs; Lymphatic Metastasis; Methylnitronitrosoguanidine; Neoplasms, Experimental; Time Factors

Nineteen male Wistar rats received N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in drinking water (83 mg/L) to initiate glandular adenocarcinoma of the stomach; eight control rats received tap water. After 12 weeks a pyloroplasty was performed on nine rats receiving MNNG and three control rats. Ten MNNG-treated rats and five control rats had no operation. All were observed for 38 weeks before being killed. No difference in the incidence of antral adenocarcinomas was found between the MNNG-treated groups; however, those without operation showed in situ changes in the duodenum and those treated with pyloroplasty showed five invasive adenocarcinomas. In this model pyloroplasty alone did not increase the risk of gastric cancer but increased the risk of duodenal tumors. Pyloroplasty apparently accelerated the gastric evacuation rate, resulting in greater insult to the duodenal mucosa. Such a condition may require a higher proliferative rate in the duodenum and may increase subsequent formation of malignant tumors.

Topics: Adenocarcinoma; Animals; Disease Models, Animal; Duodenal Neoplasms; Gastric Mucosa; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental; Pyloric Antrum; Pylorus; Rats; Rats, Inbred Strains; Stomach Neoplasms

Topics: Animals; Disease Models, Animal; Methylnitronitrosoguanidine; Neoplasms, Experimental; Rats; Stomach Neoplasms; Stomach Ulcer

In an effort to establish an animal colon tumor model suitable for biological and chemotherapy studies, 82 colon tumors were induced and transplanted in four different inbred strains of mice. Four colon tumors survived the first transplant and are now in serial passage. All are suitable for chemotherapy trials. Two tumors are highly metastatic, and at least one of these is known to be suitable for surgery-chemotherapy adjuvant studies. The effective colon carcinogens contained a (see article) molecular similarity.

Topics: Adenocarcinoma; Animals; Carcinogens; Carcinoma; Chemical Phenomena; Chemistry; Colonic Neoplasms; Dimethylhydrazines; Disease Models, Animal; Methylnitronitrosoguanidine; Methylnitrosourea; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Inbred DBA; Neoplasm Metastasis; Neoplasm Transplantation; Neoplasms, Experimental; Nitrosomethylurethane; Transplantation, Homologous

Colon tumors of mice were induced with 1, 2-dimethylhydrazine, N-nitroso-N-methylurethane, methylnitrosourea, and 4-methyl-N'-nitro-N-nitrosoguanidine. Of 82 transplantation attempts, four were successful, and the four tumors have been maintained as distinct tumor lines by subcutaneous transplantation. The tumors graded from II, adenocarcinoma, to IV, undifferentiated carcinoma. Volume-doubling times varied over a three-fold range, and metastatic potential ranged from 5 to about 100%. The tumors responded to treatment with some of the same agents found to be active in man. These included cyclophosphamide, 5-fluorouracil, and certain nitrosoureas. Preliminary evidence suggests that these tumor lines may be useful as experimental models.

Topics: Animals; Antineoplastic Agents; Colonic Neoplasms; Dimethylhydrazines; Disease Models, Animal; Methylnitronitrosoguanidine; Methylnitrosourea; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Inbred DBA; Neoplasm Transplantation; Neoplasms, Experimental; Nitrosomethylurethane; Transplantation, Homologous