methylnitronitrosoguanidine and Carcinoma--Squamous-Cell

Topics: 9,10-Dimethyl-1,2-benzanthracene; Actins; Animals; Carcinoma, Squamous Cell; Cell Transformation, Neoplastic; Cocarcinogenesis; DNA; Gene Expression Regulation, Neoplastic; Matrix Metalloproteinase 3; Metalloendopeptidases; Methylnitronitrosoguanidine; Mice; Neoplasm Metastasis; Neoplasm Proteins; Neoplasms, Multiple Primary; Papilloma; Skin Neoplasms; Tetradecanoylphorbol Acetate; Ubiquitins

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

Hypermethylation of CpG sites within the promoter region of the O6-methylguanine-DNA methyltransferase (MGMT) gene occurs frequently in human cancer, preventing both MGMT expression and repair of alkylation damage. To assess the role of MGMT in the development of mouse skin tumors induced by initiation-promotion protocols, methylation of the MGMT promoter was examined in tumor DNA using methylation-specific PCR. To determine whether MGMT promoter methylation was affected by the tumor induction protocol, tumors were initiated by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or 7,12-dimethylbenz[a]anthracene (DMBA) and promoted by 12-O-tetradecanoylphorbol-13-acetate (TPA) or mezerein. Although the MGMT promoter was not methylated in normal skin, promoter methylation was found in 56 of 136 papillomas (41.2%) and in 19 of 37 squamous cell carcinomas (51.4%). When methylation of the MGMT promoter was compared in the 4 treatment groups, hypermethylation was found more frequently in tumors initiated by DMBA and promoted by mezerein, a protocol associated with a high frequency of malignant conversion. Methylation was found in some tumors as early as 5 weeks after initiation, but the methylation frequency increased with time. MGMT promoter methylation reduced MGMT expression as determined by immunohistochemistry. Although MGMT promoter methylation was not generally correlated with ras mutations, the frequency of MGMT methylation was higher in MNNG-initiated, mezerein-promoted papillomas with mutations in Ha-ras compared to papillomas with Ki-ras. Methylation of the MGMT promoter, associated with reduced MGMT expression, is found in nearly half of mouse skin tumors, but varies with both the tumor initiator and tumor promoter, and may be a key step in the progression from papillomas to carcinomas.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinogens; Carcinoma, Squamous Cell; Diterpenes; DNA Methylation; Gene Expression Regulation, Neoplastic; Genes, ras; Humans; Methylnitronitrosoguanidine; Mice; Mutation; O(6)-Methylguanine-DNA Methyltransferase; Papilloma; Promoter Regions, Genetic; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate

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

The effects of sodium nitrite (NaNO2), in combination with one of three antioxidants, tert-butylhydroquinone (TBHQ), alpha-tocopherol (alpha-Toc) and propyl gallate (PG), on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) stomach carcinogenesis were investigated in F344 rats. Groups of 15 male rats were treated with an intragastric dose of 150 mg/kg body weight of MNNG, and starting 1 week later, were treated with 0.5% TBHQ, 1% alpha-Toc, 1% PG or basal diet with or without 0.2% NaNO2 in their drinking water until they were killed at the end of week 36. Macroscopically, in MNNG-treated animals, combined administration of alpha-Toc or PG with NaNO2 significantly increased the areas and numbers of forestomach nodules as compared with the respective antioxidant alone values. Microscopically, in MNNG-treated animals, treatment with TBHQ significantly increased the incidence and multiplicity of forestomach papillomas as compared with basal diet alone value. Combined administration of alpha-Toc with NaNO2 significantly raised the multiplicity of forestomach papillomas, with a tendency to elevation in the incidence as compared with the group given alpha-Toc alone. Incidences of forestomach moderate and/or severe hyperplasias were significantly higher in the TBHQ or PG plus NaNO2 groups than in the single compound groups. In rats without MNNG treatment, combined treatment of antioxidants with NaNO2 significantly increased the incidences of mild or moderate hyperplasia. In the glandular stomach, although the incidence of atypical hyperplasia showed a non-significant tendency for decrease with TBHQ treatment, additional administration of NaNO2 caused significant increase. These results indicate that co-administration of NaNO2 with alpha-Toc, TBHQ or PG and particularly the first, promotes forestomach carcinogenesis. Concurrent alpha-Toc, TBHQ or PG treatment with NaNO2 is likely to induce forestomach tumors in the long term.

Topics: alpha-Tocopherol; Animals; Antioxidants; Body Weight; Carcinoma, Squamous Cell; Drug Combinations; Drug Interactions; Food Preservatives; Hydroquinones; Hyperplasia; Male; Methylnitronitrosoguanidine; Papilloma; Propyl Gallate; Rats; Rats, Inbred F344; Sodium Nitrite; Stomach Neoplasms

We investigated "the "chemopreventive potential of lycopene against gastric carcinogenesis induced in male Wistar rats by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and saturated sodium chloride (S-NaCl). Administration of lycopene inhibited MNNG+S-NaCl-induced gastric carcinogenesis as revealed by the absence of carcinomas. Lipid peroxidation, reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione S-transferase (GST) and glutathione reductase (GR) were used to monitor the chemopreventive potential of lycopene. The extent of lipid peroxidation was significantly lower, whereas GSH, GPx, GST and GR were markedly enhanced in the gastric mucosa of tumour-bearing animals. Our data suggest that lycopene may exert its inhibitory effects by modulating the oxidant and antioxidant status in the gastric mucosa.

Topics: Animals; Anticarcinogenic Agents; Antioxidants; Carcinogens; Carcinoma, Squamous Cell; Carotenoids; Glutathione; Glutathione Peroxidase; Lipid Peroxidation; Lycopene; Male; Methylnitronitrosoguanidine; Rats; Rats, Wistar; Saline Solution, Hypertonic; Stomach Neoplasms

This study was undertaken to determine the effect of 5-fluorouracil on gastrointestinal carcinogenesis. Sixty rats were divided into three groups of 20 rats each. All rats were exposed to N-methyl-N'-nitro-N-nitrosoguanidine for the first 20 weeks. Group 1 rats received intraperitoneal injections of 5-fluorouracil for the first 20 weeks and were then observed for the second 20 weeks. Group 2 rats also received 5-fluorouracil injections, but for the second 20 weeks. Group 3 rats received no 5-fluorouracil treatment. Four of 20 rats in group 1 developed an invasive adenocarcinoma. In group 3, invasive squamous cell carcinoma and adenocarcinoma developed in one rat each. None of the group 2 rats had malignant lesions. These results suggested that 5-fluorouracil is not effective in suppressing the initial stage of gastrointestinal carcinogenesis with a coexisting carcinogen. Rather, the therapeutic effect is exerted in later stages of tumor progression.

Topics: Adenocarcinoma; Animals; Antimetabolites, Antineoplastic; Carcinogens; Carcinoma, Squamous Cell; Fluorouracil; Gastrointestinal Neoplasms; Injections, Intraperitoneal; Male; Methylnitronitrosoguanidine; Rats; Rats, Wistar

The modifying effect of diethyl maleate (DEM) on gastric tumor development was studied in rats initially given N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and hypertonic sodium chloride (H-NaCl 10% or 5%). Groups of animals were maintained with or without a 0.2% DEM dietary supplement after treatment with MNNG and H-NaCl and sacrificed at week 20. Forestomachs and livers cytosolic NAD(P)H:quinone-acceptor oxidoreductase (QR) activity was also analyzed. The incidences of forestomach severe hyperplasias in the MNNG + H-NaCl --> DEM groups were also significantly higher than in the MNNG + H-NaCl alone group (P < 0.01 and P < 0.05 for 5% and 10% groups, respectively). Similarly, in the glandular stomach, the numbers of preneoplastic pepsinogen 1 altered pyloric glands (PAPGs) in the MNNG + H-NaCl --> DEM groups were significantly increased (P < 0.01 for both concentrations). The QR activities in the groups treated with DEM showed 2- to 3-fold increases as compared with the control level. The results indicate that treatment with 0.2% DEM after MNNG initiation exerts enhancing effects on both forestomach and glandular stomach carcinogenesis. Induction of QR, a Phase II enzyme, activity in the rat stomach by DEM may be associated with promotion of stomach carcinogenesis rather than inhibition.

Topics: Animals; Body Weight; Carcinogenicity Tests; Carcinogens; Carcinoma, Squamous Cell; Gastric Mucosa; Male; Maleates; Methylnitronitrosoguanidine; NAD(P)H Dehydrogenase (Quinone); Papilloma; Pepsinogen A; Rats; Rats, Wistar; Saline Solution, Hypertonic; Stomach; Stomach Neoplasms

Secreted phosphoprotein 1 (spp1), the gene encoding osteopontin (OPN), is expressed in many human carcinomas, although its in vivo functions remain unclear. To delineate the role of OPN during tumor progression, we have subjected OPN null mutant mice to repeated applications of a mutagen/carcinogen to induce cutaneous squamous cell carcinoma. OPN null animals exhibited accelerated tumor growth and progression and had a greater number of metastases per animal compared with wild-type animals. However, metastases in the OPN null animals were significantly smaller than in controls. When injected into nude mice, the growth of OPN null tumor lines and the same lines engineered to reexpress spp1 recapitulated the growth differences observed in the progression study. These differences in tumor growth inversely correlated with the degree of macrophage infiltration. Slower-growing, OPN-producing tumors contained significantly more macrophages, although a higher proportion were mannose receptor positive, a characteristic of differentiated resting macrophages. In vitro, OPN null cell lines displayed decreased survival at clonal density compared with OPN-producing lines, an observation consistent with the smaller metastases of the OPN null mice. Overall, we provide evidence for a model where host-derived OPN acts as a macrophage chemoattractant, whereas tumor-derived OPN is able to inhibit macrophage function and enhances the growth or survival of metastases.

Topics: Animals; Carcinogens; Carcinoma; Carcinoma, Squamous Cell; Cell Count; Cell Division; Disease Progression; Female; Male; Methylnitronitrosoguanidine; Mice; Neoplasm Proteins; Osteopontin; Papilloma; Phenotype; Sialoglycoproteins; Skin Neoplasms

To investigate the relationship between p53 gene mutations and mouse skin tumors induced by three-step carcinogenesis.. The exons 5-8 of p53 gene were examined in 37 DMBA-TPA-MNNG induced mouse skin tumors [including 6 mice with papillomas, 15 mice having well differentiated squamous cell carcinomas (SCCI) and 16 mice with intermediately differentiated squamous cell carcinomas (SCC II)].. No p53 gene mutation was detected in the papilloma group, whereas 25.8% (8/31) of the SCC group had p53 gene mutations (4/15 of the SCC I mice and 4/16 of the SCC II mice). A total of 9 mutations were found in 8 mice with SCC, of which 7 were located in exon 8 and 7 were G-->A transitions.. The p53 gene mutations occurred during the process of malignant transformation from papilloma to SCC induced by three step carcinogenesis.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinoma, Squamous Cell; Cell Transformation, Neoplastic; Exons; Genes, p53; Methylnitronitrosoguanidine; Mice; Mice, Inbred SENCAR; Papilloma; Point Mutation; Skin Neoplasms; Tetradecanoylphorbol Acetate

Chinese hamster V79 monolayers, V79 spheroids, and SCCVII murine tumours were examined for DNA damage using the alkaline comet assay and for cell killing by measuring clonogenicity following a 1-h exposure to doxorubicin, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 4-nitroquinoline-N-oxide (4-NQO), etoposide, or 3-amino-1,2,4-benzotriazine-1,4-dioxide (tirapazamine). Greater heterogeneity in DNA damage was evident in spheroids compared to monolayers exposed to these drugs, and cell survival was correlated with the fraction of cells which lacked sufficient DNA damage following treatment with tirapazamine or doxorubicin. Cell sorting experiments verified that subpopulations of cells resistant to DNA damage were also more resistant to cell killing. Significant heterogeneity was observed in cells from SCCVII tumours exposed to tirapazamine and etoposide, and comet DNA content was used to independently assess DNA damage to aneuploid tumour cells and diploid host cells. These results suggest that, for some drugs, the comet assay may be an effective method of identifying drug-resistant cells in solid tumours.

Topics: Animals; Carcinoma, Squamous Cell; Cell Line; Cell Survival; Clone Cells; Cricetinae; Cricetulus; DNA Damage; DNA Mutational Analysis; Drug Resistance; Male; Methylnitronitrosoguanidine; Mice; Mice, Inbred C3H; Mutagenicity Tests; Organoids; Tumor Cells, Cultured

To develop mouse strains useful for studies of susceptibility and resistance to the induction of skin tumors, three new inbred SENCAR strains were independently derived by random inbreeding of outbred SENCAR mice. Characterization of these mice for sensitivity to skin tumor development indicated that mice of all three strains displayed increased sensitivity to initiation by 7,12-dimethylbenz[a]anthracene (DMBA), urethane, or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and promotion by 12-O-tetradecanoylphorbol-13-acetate (TPA). Promotion by mezerein as well as carcinogenesis by repeated treatment with DMBA or MNNG produced papillomas with a high frequency of conversion to squamous cell carcinomas (SCCs). Compared with outbred SENCAR mice, development of both squamous papillomas and carcinomas was increased at least two-fold by all protocols tested. The F1 hybrid between SENCARA/Pt males and resistant BALB/cAnPt females was resistant to the induction of both papillomas and SCCs after initiation by 2 microg of DMBA and promotion by 20 weekly applications of 2 microg of TPA. Papillomas developed in all of the SENCARA/Pt mice, none of the BALB/cAnPt mice, and 12% of the F1 progeny. Thus, at these doses of initiator and promoter, resistance was incompletely dominant in the F1 hybrid. However, the responsiveness of the F1 mice could be increased substantially by increasing the dose of the promoter.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinogens; Carcinoma, Squamous Cell; Cocarcinogenesis; Disease Susceptibility; Diterpenes; Female; Male; Methylnitronitrosoguanidine; Mice; Mice, Inbred BALB C; Mice, Inbred SENCAR; Papilloma; Phenotype; Sensitivity and Specificity; Skin Neoplasms; Terpenes; Urethane

Human tumor cells have properties in vitro or in surrogate hosts that are distinct from those of normal cells, such as immortality, anchorage independence, and tumor formation in nude mice. However, different cells from individual tumors may exhibit some, but not all of these features. In previous years, human tumor cell lines derived from different tumor and tissue types have been studied to determine those molecular changes that are associated with the in vitro properties listed above and with tumorigenicity in nude mice. In the present study, seven cell lines derived from human tumors were characterized for p53 and ras mutations that may occur in SCC tumor phenotypes and for tumor formation in nude mice. This investigation was designed to examine whether co-occurrence of mutated ras and p53 lead to a malignant stage in the progression process. None of the seven cell lines contained mutations in the recognized "hot spots" of the p53 tumor suppressor gene, but four had a nonsense/splice mutation in codon 126 and a mutation in codon 12 of the H-ras gene. The remaining three cell lines had p53 mutations in intron 5, in codon 193, and a missense mutation in codon 126, respectively. Four of seven cell lines were nontumorigenic; two of these cell lines contained a nonsense p53-126 mutation and mutated ras; one had a missense mutation at codon 126 but no mutated ras; the the fourth had only a p53 mutation at codon 193. Two of the nontumorigenic cell lines were converted to tumorigenicity after treatment with methyl methanesulfonate or N-methyl-N'-nitro-N-nitrosoguanidine with no apparent additional mutations in either gene. Our analysis revealed that there was a high frequency of genetic diversity and mutations in both p53 and H-ras. There was also a lack of a causal relationship in the presence of mutations in p53 and the cells' ability to exhibit a malignant potential in nude mice.

Topics: Animals; Autoradiography; Blotting, Northern; Carcinoma, Squamous Cell; DNA, Complementary; Gene Expression Regulation, Neoplastic; Genes, p53; Genes, ras; Humans; Male; Methyl Methanesulfonate; Methylnitronitrosoguanidine; Mice; Mice, Nude; Mutation; Phenotype; RNA, Messenger; Transfection; Tumor Cells, Cultured

There are divergent opinions on the effect of ethanol in the carcinogenesis of gastroduodenal tumors. The effect of the synchronous application of 11% ethanol or wine (11% ethanol) and N-methyl-N'-nitro-N-nitrosoguanidine (100 micrograms/ml, MNNG) in a drinking solution on the incidence of gastroduodenal tumors was evaluated. Sixty outbred male Wistar rats were distributed among three groups. The animals drank MNNG and ethanol or wine for six months and consumed the same quantity of MNNG. Then they consumed a normal diet until the 13th month, when the experiment was terminated. The stomach and duodenum were examined histologically. In the stomach, 15 tumors (2 squamous paillomas, 4 squamous carcinomas, 1 sarcoma, and 8 adenocarcinomas) and 4 cases of dysplasia were found; in the duodenum, there were four cases of adenocarcinoma. There were 6 cases of multiple tumors. Incidence of forestomach tumors did not differ among the groups, whereas the incidence of glandular stomach carcinoma and duodenal carcinoma was significantly lower in the groups treated with 11% ethanol or wine than in the control group. MNNG was not inactivated by ethanol in the drinking solutions. We concluded that the inhibitory effect on gastroduodenal carcinogenesis is the result of 11% ethanol ingestion and its protective action on the mucosa and not of the wine's nonethanol components.

Topics: Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Drinking; Duodenal Neoplasms; Ethanol; Male; Methylnitronitrosoguanidine; Rats; Rats, Wistar; Sarcoma, Experimental; Stomach Neoplasms; Wine

Skin papillomas and squamous cell carcinomas (SCCs) are induced in mice by tumor initiation with a carcinogen followed by tumor promotion with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). These usually arise from preneoplastic lesions characterized by epidermal proliferation and hyperplasia, dermal edema, and inflammation. To evaluate the role of polypeptide growth factors in chemically induced skin carcinogenesis, we used transgenic mice carrying the cDNA for a TGF-beta related molecule, bone morphogenetic protein-4 (BMP-4), under the control of the regulatory elements of the cytokeratin IV* gene in a skin carcinogenesis protocol. Control non-transgenic littermates and BMP-4 transgenic mice were treated with a single dose of a carcinogen, N-methyl-N'-nitrosoguanidine (MNNG), and biweekly with the tumor promoter TPA for 9 months. In control littermates TPA induced epidermal hyperproliferation, atypia with "dark" cells, and dermal inflammation, resulting in papillomas and SCCs in 13 of 26 animals tested. In BMP-4 transgenic mice, TPA treatment induced the expression of the BMP-4 transgene in interfollicular epidermis but only minimal epidermal thickening, hyperproliferation, and inflammation were noted after the initial dose of TPA. Furthermore, the mitotic indices in transgenic epidermis after 9 months of TPA treatment were significantly lower than the corresponding indices from untreated transgenic epidermis. Consequently, none of the 22 transgenic animals tested developed papillomas or SCCs. In conclusion, we have shown that the TPA induced expression of the BMP-4 transgene blocks proliferation and inflammation in skin, steps that are critical to the subsequent formation of papillomas and SCCs and we characterized an inducible promotersystem which expresses polypeptides in interfollicular epidermis after exogenous stimulation.

Topics: Animals; Bone Morphogenetic Proteins; Bromodeoxyuridine; Carcinoma, Squamous Cell; Cell Division; Epidermis; Methylnitronitrosoguanidine; Mice; Mice, Transgenic; Papilloma; Proteins; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Transforming Growth Factor beta

The distribution of keratins in N-methyl-N'-nitro-N-nitrosoguanidine-induced oesophageal carcinomas in shrews was tested immunohistochemically, using a panel of seven different monoclonal antibodies. The studies were done on methacarn-fixed paraffin-embedded tissue, using the labelled streptavidin biotin method, and the relationship between morphological characteristics and keratin reaction patterns in carcinomas was analysed and compared with that in adjacent "normal" oesophageal epithelium. In the normal oesophageal epithelia, KL1, AE1, AE3, CK8.12, and CK4.62 stained suprabasal cells, 312C8-1 reacted to basal cells, and KS-1A3 labelled all epithelial cells. In squamous cell carcinomas, almost all the cancer cells were labelled strongly by 312C8-1 and weakly by KS-1A3, while a few cells in the centres of the keratinized foci were stained by KL1, AE1, AE3, CK8.12, and CK4.62. Like human oesophageal carcinomas, shrew oesophageal carcinomas maintain expression of human keratin 14, as determined by 312C8-1. The expression of human keratin 13, as determined by KS-1A3, was down-regulated.

Topics: Animals; Antibodies, Monoclonal; Carcinoma, Squamous Cell; Esophageal Neoplasms; Female; Immunohistochemistry; Keratins; Methylnitronitrosoguanidine; Shrews

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

The effects of combined treatment with NaNO2 and phenolic compounds on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) stomach carcinogenesis were investigated in F344 rats. In the first experiment, groups of 15-20 male rats were treated with an intragastric dose of 150 mg/kg body weight of MNNG, and starting 1 wk later, were given 2.0% butylated hydroxyanisole, 0.8% catechol, 2.0% 3-methoxycatechol or basal diet either alone or in combination with 0.2% NaNO2 in the drinking water until they were killed at week 52. All three antioxidants significantly enhanced forestomach carcinogenesis without any effect of additional NaNO2 treatment. However, in the absence of MNNG pretreatment, the grade of forestomach hyperplasia in the catechol and 3-methoxycatechol groups was significantly increased by the combined treatment with NaNO2. In a second experiment, the combined effects of various phenolic compounds and NaNO2 on cell proliferation in the upper digestive tract were examined. Groups of 5 rats were given one of 24 phenolic compounds or basal diet either alone or in combination with 0.3% NaNO2 for 4 weeks and then killed. Particularly strong enhancing effects in terms of thickness of the forestomach mucosa were seen with t-butylhydroquinone (TBHQ), catechol, gallic acid, 1,2,4-benzenetriol, dl-3-(3,4-dihydroxyphenyl)-alanine and hydroquinone in combination with NaNO2. In the glandular stomach, similar enhancing effects were evident in 11 cases, and in the esophagus with phenol, TBHQ and gallic acid. These results demonstrate that NaNO2 can augment cell proliferation induced in the stomach epithelium by various phenolic compounds.

Topics: Animals; Butylated Hydroxyanisole; Carcinoma, Squamous Cell; Catechols; Cell Division; Hyperplasia; Male; Methylnitronitrosoguanidine; Phenols; Rats; Rats, Inbred F344; Sodium Nitrite; Stomach; Stomach Neoplasms

In experiment I, short-term effects of combined treatment with anti-oxidants, sodium ascorbate (NaAsA) and sodium nitrite (NaNO2) on forestomach cell proliferation were examined in F344 male rats. Groups of 5 animals aged 6 weeks were treated for 4 weeks with 0.8% catechol, 0.8% hydroquinone, 1% tert-butyl-hydroquinone (TBHQ), 2% gallic acid or 2% pyrogallor alone or in combination with 0.3% NaNO2 in the drinking water and/or 1% NaAsA in the diet. The thicknesses of forestomach mucosa in rats treated with anti-oxidants and NaNO2 in combination were greater than those with antioxidant alone and additional NaAsA treatment further enhanced the thickening of mucosa. It was noteworthy that values for mucosae of animals treated with NaNO2 and NaAsA without anti-oxidant were similar to those for anti-oxidants. In experiment 2, effects of combined treatment with NaAsA or ascorbic acid (AsA) and NaNO2 on carcinogenesis were examined in F344 male rats with or without N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) pre-treatment. Groups of 20 or 15 rats, respectively, aged 6 weeks, were given a single intra-gastric administration of 150 mg/kg body weight of MNNG in DMSO:water = 1:1 or the vehicle alone by stomach tube. Starting 1 week later, they received supplements of 1% NaAsA or 1% AsA in the diet and 0.3% NaNO2 in drinking water in combination, each of the individual chemicals alone, or basal diet until the end of week 52. In MNNG-treated animals, incidences of forestomach papillomas and carcinomas were significantly enhanced in the NaNO2 alone group (84 and 47%, respectively) as compared with the basal diet group (30 and 10%), with further significant increase in carcinomas occurring with additional NaAsA (79%, p < 0.05) or AsA (85%, p < 0.05) treatment. In animals without MNNG, all animals in the NaNO2 group demonstrated mild hyperplasia, additional administration of NaAsA or AsA remarkably enhancing the grade of hyperplasia, and resulting in 53% and 20% incidences, respectively, of papillomas. Thus NaNO2 was demonstrated to exert promoter action for forestomach carcinogenesis, with NaAsA and AsA acting as co-promoters. The results strongly indicate that combined treatment with NaAsA or AsA and NaNO2 may induce forestomach carcinomas in the long term.

Topics: Animals; Ascorbic Acid; Body Weight; Carcinoma, Squamous Cell; Drug Interactions; Kidney; Liver; Male; Methylnitronitrosoguanidine; Organ Size; Papilloma; Rats; Rats, Inbred F344; Sodium Nitrite; Stomach Neoplasms

A 1-ml dose of 4.5 M NaCl was given intragastrically to male Wistar rats at 10 min, 1 h, 4 h, 12 h, 24 h or 48 h before a single intragastric dose of 250 mg/kg N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). After 52 weeks the incidence of forestomach squamous cell carcinoma was 21% in control animals receiving MNNG alone. The cancer incidence in the forestomach varied with the time elapsed between application of NaCl and MNNG, and was significantly increased in animals pretreated with NaCl 4 h (43%), 12 h (54%) and 24 h (41%) before MNNG. These results show that salt has a cocarcinogenic effect on initiation of forestomach carcinogenesis in rats, and that this effect depends on the time interval between pretreatment with NaCl and application of MNNG. Gastric adenocarcinomas occurred more frequently in the antrum (78%) than in the corpus (22%). The incidence of gastric adenocarcinoma in animals pretreated with salt before application of MNNG (11%-22%) was not significantly influenced by the time elapsed between pretreatment with salt and application of MNNG, and did not differ from animals receiving MNNG alone (18%). The lack of a cocarcinogenic effect of NaCl on glandular gastric carcinogenesis might be due to the use of dimethyl/sulfoxide as solvent for MNNG.

Topics: Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Drug Administration Schedule; Male; Methylnitronitrosoguanidine; Papilloma; Rats; Rats, Wistar; Saline Solution, Hypertonic; 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

Initiation and promotion in mouse skin carcinogenesis produce multiple benign tumors, squamous papillomas, but only a few squamous cell carcinomas. The spontaneous conversion from the benign to the malignant phenotype occurs over many months and in stages, but induced malignant conversion can be accomplished more rapidly by exposure of papilloma-bearing mice to mutagens or by transfection of papilloma cell lines with specific oncogenes. The analysis of genetic targets responsible for carcinogen-induced neoplastic progression would be facilitated by the development of in vitro models where the process is rapid, focal, and quantitative. To this end, primary newborn mouse keratinocytes were initiated in vitro by the introduction of the v-rasHa oncogene via a defective retrovirus. Recipient cells produce squamous papillomas and have a high proliferation rate in culture medium with 0.05 mM Ca2+, but fail to grow in medium with 0.5 mM Ca2+ which is permissive for growth of malignant keratinocytes. When v-rasHa-keratinocytes were exposed to mutagens in vitro, proliferative foci emerged after culture in 0.5 mM Ca2+ for 4 weeks. These foci stained intensely red with rhodamine stain, could be easily quantitated, and readily incorporated bromodeoxyuridine. Dose-response studies with several mutagens indicated that the number of foci increased with concentration to the point where excessive cytotoxicity developed. Mutagens varied in potency for producing foci in the following order: cis-diamminedichloroplatinum greater than or equal to benzo(a)pyrene diolexpoxide I greater than N-methyl-N'-nitro-N-nitrosoguanidine greater than or equal to 4-nitroquinoline-N-oxide greater than N-acetoxy-acetyl- aminofluorene. The tumor promoter 12-O-tetradecanoylphorbol-13-acetate was inactive in the assay. A subset of cell lines derived from foci produced malignant tumors in vivo, while others were not tumorigenic. Analysis of DNA from cell lines and tumors revealed that most tumorigenic cell lines maintained the v-rasHa genome, whereas the viral sequences were deleted in nontumorigenic cell lines. Immunohistochemical analysis indicated that proliferative foci and quiescent v-rasHa keratinocytes expressed keratin 8, a marker of v-rasHa expression in cultured keratinocytes. Cells in foci, but not v-rasHa control cells, expressed keratin 13, a marker which is strongly associated with the malignant progression of skin tumors in vivo. This in vitro assay provides a quantitative model to

Topics: Animals; Animals, Newborn; Base Sequence; Carcinogens; Carcinoma, Squamous Cell; Cell Transformation, Neoplastic; Cells, Cultured; Epidermal Cells; Epidermis; Genes, ras; Keratinocytes; Keratins; Methylnitronitrosoguanidine; Mice; Mice, Inbred BALB C; Molecular Sequence Data; Oligodeoxyribonucleotides; Papilloma; Polymerase Chain Reaction; Skin Neoplasms; Tetradecanoylphorbol Acetate; Transfection

The sensitivity of outbred SENCAR mice and inbred SENCAR (SSIN) mice to multistage carcinogenesis was studied. Tumors were induced using either 7,12-dimethylbenz[a]anthracene or N-methyl-N'-nitro-N-nitrosoguanidine as initiators and 12-O-tetradecanoylphorbol-13-acetate or benzoyl peroxide as promoting agents. Although the number of papillomas per mouse was higher in SSIN than in outbred SENCAR mice, the number of carcinomas observed in the SSIN strain was significantly lower regardless of the initiator or promoter used. It was also observed that the expression of markers of premalignant progression (i.e., dysplasia, expression of keratin K13, and loss of keratin K1 expression) was markedly suppressed in SSIN papillomas. After 50 wk of promotion with 12-O-tetradecanoylphorbol-13-acetate, the pattern of expression of K13 and K1 in SSIN mice was comparable to the pattern observed in outbred SENCAR mice after 10 to 20 wk of promotion with 12-O-tetradecanoylphorbol-13-acetate. It was also observed that 67% of the tumors induced in SSIN mice by initiation with 7,12-dimethylbenz[a]anthracene exhibited a mutation in codon 61 of the Ha-ras-1 gene. This latter finding suggests that the differences observed in tumor progression between the inbred strain and the outbred stock are not related to a genetic alteration in the Ha-ras-1 gene but rather to an independent event that we have postulated to involve a putative suppressor gene. The data reported here suggest that the putative gene(s) that confers susceptibility to tumor promotion was segregated from the gene(s) involved in tumor progression during selection and inbreeding of the SENCAR mouse stock.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Benzoyl Peroxide; Carcinoma, Squamous Cell; Female; Genes, ras; Keratins; Methylnitronitrosoguanidine; Mice; Mutation; Papilloma; Skin Neoplasms; Species Specificity; Tetradecanoylphorbol Acetate

Promotion effects of the o-dihydroxybenzene derivatives, protocatechuic acid (PCA), dopamine hydrochloride (DAH), dl-dopa and caffeic acid on forestomach and glandular stomach carcinogenesis were investigated in rats pretreated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Groups of 20 male F344 rats were given a single intragastric administration of 150 mg/kg body wt MNNG and starting 1 week later than received diet containing 1.5% PCA, 1.5% DAH, 1.5% dl-dopa or 1% caffeic acid or basal diet alone for 51 weeks and then killed. Other groups of 10-15 rats were given PCA, DAH, dl-dopa or basal diet alone without the MNNG pretreatment. On histological assessment, the incidences of forestomach papillomas and squamous cell carcinomas were significantly enhanced in the group treated with caffeic acid (95 and 100%) as compared with the control values (35 and 10%). Although the incidence was not different, the number of papillomas per rat in the group given DAH (0.79 +/- 0.79) was also significantly increased (0.35 +/- 0.49). PCA and dl-dopa treatments did not modify the development of neoplastic lesions in the forestomach epithelium to any significant extent. None of the four chemicals enhanced glandular stomach carcinogenesis. The results thus demonstrated that whereas caffeic acid and DAH respectively, exert strong and weak promotion activity for rat forestomach carcinogenesis this promotion potential is not shared by all dihydroxybenzene derivatives. An influence of substituents in the para position in addition to the o-dihydroxy moiety is indicated.

Topics: Adenocarcinoma; Animals; Body Weight; Caffeic Acids; Carcinogens; Carcinoma, Squamous Cell; Dihydroxyphenylalanine; Dopamine; Drug Synergism; Epithelium; Hydroxybenzoates; Hyperplasia; Leiomyosarcoma; Male; Methylnitronitrosoguanidine; Papilloma; Rats; Rats, Inbred F344; Stomach; Stomach Neoplasms

The mechanisms of reversibility of basal cell hyperplasia in the rat forestomach were investigated. Male F344 rats were given an initial single gastric intubation of N-methyl-N'-nitro-N-nitorosoguanidine and then received 2% butylated hydroxyanisole in the diet from the third week to the 26th week. Rats were killed at weeks 26 and 46 after return to basal diet and their forestomachs were removed. Bromouracil deoxyriboside (BUdR) was administered as a single i.p. injection 1 h before death or by osmotic minipump (120 micrograms/h) continuously for 7 days before death. Additional animals were maintained for 2 or 4 weeks after removal of osmotic minipumps to allow assessment of the fate of proliferating populations. In each case BUdR-labeled cells were demonstrated by immunohistochemistry by immunohistochemistry. At week 26, hyperplastic changes were more pronounced than at week 46. Squamous cells above basal cell hyperplasias were strongly labeled even 4 weeks after cessation of continuous BUdR Three-dimensional reconstruction of persisting basal cell hyperplasias showed almost all basal cells limited to a thin sheet in direct contact with the squamous cell layer, occasional separate islands demonstrating differentiation to squamous cells and formation of epidermal cysts. The results thus showed that the mechanism of reversibility of basal cell hyperplasia involves differentiation of basal cells to squamous cells.

Topics: Animals; Bromodeoxyuridine; Butylated Hydroxyanisole; Carcinoma, Basal Cell; Carcinoma, Squamous Cell; Cell Differentiation; Cell Transformation, Neoplastic; Gastric Mucosa; Hyperplasia; Image Processing, Computer-Assisted; Male; Methylnitronitrosoguanidine; Rats; Rats, Inbred F344; Stomach; Stomach Neoplasms

Effects of sodium chloride (NaCl) and ethanol on gastric tumor development in rats after treatment with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were studied. MNNG, dissolved in distilled water (5 g/liter), was administered orally once by gastric tube at a dose of 0.25 ml/10 g body weight to 4-week-old ACI rats. After this carcinogen initiation, animals were fed on a diet containing 10% NaCl (Group 2) or normal diet with 10% ethanol in the drinking water (Group 4). MNNG alone (Group 1), NaCl alone (Group 3), ethanol alone (Group 5), and control (Group 6) animals were also maintained. All survivors were killed one year after the MNNG application. Incidences of tumors in the forestomach and glandular stomach were significantly increased in Group 2 as compared to Group 1 (P less than 0.05). The height of the pyloric mucosa was significantly greater in Group 2 than in Groups 4, 5 or 6 (P less than 0.05). In the fundic area, the mucosal height was significantly decreased in Group 4 as compared to Group 6 (P less than 0.05). The present results demonstrate that whereas tumors in the glandular stomach and forestomach are both promoted by NaCl, ethanol is without influence. Furthermore, NaCl, a promoter of glandular stomach tumorigenesis also increases cell proliferation.

Topics: Animals; Body Weight; Carcinogens; Carcinoma, Squamous Cell; Ethanol; Gastric Mucosa; Intestinal Neoplasms; Male; Methylnitronitrosoguanidine; Neoplasm Metastasis; Organ Size; Rats; Rats, Inbred Strains; Sodium Chloride; Stomach Neoplasms

Squamous cell carcinomas (SCC) of the mouse skin were produced by three different protocols of chemical carcinogenesis, i.e., complete carcinogenesis with 7,12-dimethylbenz(a)anthracene (DMBA) two-stage carcinogenesis with DMBA as initiator, 12-O-tetradecanoyl-phorbol-13-acetate (TPA) as promoter and three stage carcinogenesis with DMBA, TPA and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) as third-stage agent or progressor. Tumors were sequentially studied at weeks 38-52 of treatment. Although no significant differences in the rate of appearance of gamma-glutamyl transpeptidase (GGT) could be seen, a larger number of SCC produced by complete carcinogenesis protocols were GGT-negative. This coincided with the higher grade of malignancy of these tumors as evaluated by histopathology. In general terms high-grade tumors were seen more frequently in the complete carcinogenesis experiment than in the other two protocols. SCC produced by complete carcinogenesis also exhibited a markedly higher DNA index than the SCC from the other experimental groups. All three protocols were very effective in producing late metastasizing tumors, and no significant differences could be established in the incidence of spontaneous lung metastasis. This shows that, contrary to general knowledge, if adequately observed for more than 40 weeks, SCC of the murine skin is able to metastasize in the lung in approximately 30% of cases. Nevertheless, complete carcinogenesis-induced SCC were usually of higher histological grade, a proportion of these were GGT-negative and produced more multiple or diffuse metastases than the tumors induced by the multistage protocols.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinoma, Squamous Cell; DNA, Neoplasm; Female; gamma-Glutamyltransferase; Lung Neoplasms; Methylnitronitrosoguanidine; Mice; Neoplasm Metastasis; Skin Neoplasms; Tetradecanoylphorbol Acetate; Time Factors

The effects of butylated hydroxyanisole (BHA) pretreatment on subsequent low dose N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or N,N-dibutylnitrosamine (DBN) treatment on forestomach or esophageal carcinogenesis were investigated in male F344 rats. Groups of animals were pretreated with 2% BHA or basal diet alone for 24 weeks and then were given 20 mg/kg body wt MNNG once every 2 weeks, 0.025% DBN in drinking water continuously or basal diet alone for the subsequent 24 weeks. Further groups of rats were similarly treated with BHA or basal diet alone for 24 weeks, placed on basal diet for the next 24 weeks and then treated with MNNG, DBN or basal diet alone for the subsequent 24 weeks. Animals were killed 48 or 72 weeks after the beginning of the experiment. Histopathological examination showed that the incidence of forestomach tumors was not significantly affected by the BHA pretreatment in the MNNG-treated groups. On the other hand, the incidence of esophageal squamous cell carcinomas was lower in the group pretreated with BHA followed by DBN than in that treated with basal diet followed by DBN (48 week experiment). There was no significant difference in esophageal tumor incidence in the 72 week experiment. The results thus indicate that continuous treatment with 2% BHA for 24 weeks does not exert initiating activity on forestomach and esophageal epithelia.

Topics: Animals; Body Weight; Butylated Hydroxyanisole; Carcinogens; Carcinoma, Squamous Cell; Esophageal Neoplasms; Esophagus; Hyperplasia; Male; Methylnitronitrosoguanidine; Nitrosamines; Organ Size; Papilloma; Rats; Rats, Inbred F344; Stomach; Stomach Neoplasms

Peculiarities of carcinogenic effect of N-methyl-N'-nitro-N-nitrosoguanidine administered through a stomach tube on rats were studied in 30 rats given 1-2 ml MNNG dissolved in distilled water (5 mg/ml) through a gastric tube for 2-3 days. The procedure is repeated every 4-10 days. This intermittent carcinogen administration continued until week 20; the animals were killed on week 25. All effective 26 (100%) rats had multiple papillomas and squamous cell carcinomas of the forestomach, 5 (19.2%) had adenomatous hyperplasias and adenocarcinomas of the glandular stomach, 7 (26.9%) had adenocarcinomas and sarcomas of the small intestine.

Topics: Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Intestinal Neoplasms; Intestine, Small; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental; Papilloma; Rats; Sarcoma, Experimental; Stomach Neoplasms; Time Factors

The mouse monoclonal antibody OSU 22-3 was prepared using cells from a squamous cell carcinoma (SCC) as an immunogen. This antibody reacts with an antigen found on squamous cell carcinomas but does not react with normal keratinocytes. This antibody and two antibodies that react with normal keratinocytes were used as markers of malignant and normal phenotypes. These markers were used to evaluate several spontaneous and carcinogen initiated SCC tumors and to identify the expression of an antigen associated with a malignant phenotype. A variety of subpopulations in carcinogen initiated tumors and spontaneous SCC tumors were noted. The subpopulations that reacted only with MoAb OSU 22-3 exhibited features of anchorage independent growth and cellular invasiveness, and formed progressively growing tumors in nude mice. Other SCC spontaneous tumor cell subpopulations reacted with the antibodies associated with normal keratinocytes. These cells did not proliferate in vitro and did not form tumors in the nude mouse. There were other carcinogen transformed cells which reacted with MoAb OSU 22-3 but not with the antibodies associated with normal keratinocytes. These cells exhibited anchorage independent growth and cellular invasiveness but did not form tumors in nude mice. We conclude from this work that human SCC tumors contain multiple cell populations. These cell populations have varied growth properties and express surface antigens that may indicate their malignant vigor. Carcinogen transformed keratinocytes do exhibit some of the characteristics of SCC tumor phenotypes but not the property of malignant progressively growing cells on a routine and consistent basis. This feature is transiently and inconsistently expressed in a surrogate host by populations prepared from spontaneous SSC tumors.

Topics: Animals; Antibodies, Monoclonal; Carcinogens; Carcinoma, Squamous Cell; Cell Transformation, Neoplastic; Dose-Response Relationship, Drug; Epidermal Cells; Epidermis; Humans; Keratins; Lethal Dose 50; Male; Methylnitronitrosoguanidine; Mice; Mice, Nude; Neoplasm Staging; Phenotype; Skin Neoplasms; Tumor Cells, Cultured

Topics: Amino Acid Sequence; Base Sequence; Biomarkers, Tumor; Blotting, Northern; Blotting, Southern; Carcinogens; Carcinoma, Squamous Cell; DNA; Fibroblasts; Gene Expression Regulation; Genes, Dominant; Genes, ras; Methylnitronitrosoguanidine; Molecular Sequence Data; Neoplasms, Radiation-Induced; Papilloma; Plasmids; Proto-Oncogenes; RNA; Skin Neoplasms; Suppression, Genetic; Transfection

Epidermal growth factor inhibits proliferation of A431 cells when added to the cultural medium. Strains of A431 cells, resistant to EGF (800 ng/ml), were obtained by one-step selection after the treatment of these cells by 1-methyl-3-nitro-1-nitrosoguanidine (MNNG). Two of the obtained strains differ from the initial line in the EGF reception.

Topics: Animals; Carcinoma, Squamous Cell; Cell Division; Cell Line; Depression, Chemical; Dose-Response Relationship, Drug; Drug Resistance; Epidermal Growth Factor; ErbB Receptors; Humans; Iodine Radioisotopes; Methylnitronitrosoguanidine; Tumor Cells, Cultured

In order to establish an effective method to induce selectively experimental dog esophageal carcinoma, we compared the restricted oral administration of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) with projecting spout with the ad libitum oral administration of it. Five dogs were given a solution of ENNG at a concentration of 50mg/l with restricted oral administration with projecting spout for 52 weeks. In all of them, elevated type of esophageal lesions were endoscopically observed soon after the cessation of the ENNG administration. Histological examination revealed that besides the multiple squamous cell carcinomas of the esophagus, various degrees of dysplasias were seen. Two dogs had metastasizes to the regional lymph nodes and one dog had metastatic lesions in the lung. Gastric carcinomas were also seen in four dogs. Another five dogs were given ad libitum the same concentration of ENNG solution. Gastric carcinomas were induced in four dogs, but esophageal carcinomas were seen in small lesions in two dogs. The restricted oral administration of ENNG with projecting spout is a reliable method for the selective induction of esophageal carcinoma in dog.

Topics: Administration, Oral; Animals; Carcinogens; Carcinoma, Squamous Cell; Dogs; Esophageal Neoplasms; Female; Male; Methylnitronitrosoguanidine; Papilloma; Stomach Neoplasms

The pathologic characteristics of gastric tumors induced by single injections of N-methyl-N'-nitro-N-nitrosoguanidine (15 mg) solution and N-methyl-N-nitrosourea (10 mg) solution in 0.1 ml dimethylformamide were studied in 23 noninbred rats. The chemicals were injected into the antropyloric segment of the stomach. By months 11-15, specific changes in the glandular epithelium had developed at that site in 20 rats: dysplasia--in 6, precancer--7, and adenocarcinoma in 7 animals. Also, there were papillomas (6), squamous cell carcinoma (3), precancer and sarcoma (4) in various segments of the organ.

Topics: Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Cocarcinogenesis; Male; Methylnitronitrosoguanidine; Methylnitrosourea; Papilloma; Precancerous Conditions; Rats; Sarcoma, Experimental; Stomach Neoplasms

Reflux of duodenal contents into the stomach occurs in patients with pyloric incompetence and after gastric resection when bile-diverting procedures are omitted. In such settings duodenal contents have been considered to favor the development of gastric cancer. We have studied the effect of chronic duodenogastric reflux on gastric tumor promotion in rats treated with N-methyl-N'-nitrosoguanidine (MNNG) in an experimental design that avoids physical trauma to the glandular stomach. Thus the effect of trauma-induced tissue repair on carcinogenesis is eliminated, and duodenogastric reflux is isolated as an experimental parameter. To achieve such reflux the first jejunal loop was anastomosed to the forestomach in rats. Animals were exposed to MNNG in drinking water (83 mg/L) for 12 weeks before induction of reflux. Experimental groups were as follow: I, reflux plus MNNG (n = 32); II, MNNG alone (n = 27); III, reflux alone (n = 28); IV, control (n = 25). The experiment was terminated after 56 weeks. Only animals that had survived for 90 days were included in the effective number of animals, which allowed for equal chances of tumor development. In no animal that died earlier had tumors developed. Animals with reflux plus MNNG treatment had significantly more glandular neoplasms (12/32) than did animals with MNNG treatment alone (4/27; p less than 0.05). Similarly, more animals with squamous cell neoplasms were recorded in group I (9/32) than in group II (2/27; p less than 0.05). In consideration of all tumors of epithelial and mesenchymal origin, more gastric malignant tumors were observed in group I (9/32) than in group II (2/27; p less than 0.05). It is concluded that chronic exposure to duodenal contents promotes the development of gastric neoplasia.

Topics: Adenocarcinoma; Adenoma; Animals; Carcinoma, Squamous Cell; Cocarcinogenesis; Duodenogastric Reflux; Male; Methylnitronitrosoguanidine; Rats; Rats, Inbred Strains; Stomach Neoplasms

The modifying effects of five phenolic antioxidants on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-initiated forestomach and glandular stomach carcinogenesis were investigated in male F344 rats. Groups of 20 rats were given an intragastric dose of 150 mg/kg body weight MNNG, and starting from 1 week later received diet supplemented with 0.8% catechol (CC), 1.0% 2-tert-butyl-4-methylphenol, 1.5% p-tert-butyl-phenol, 1.5% methylhydroquinone, 1.5% 4-methoxyphenol (4MP), or basal diet alone for 51 weeks. Further groups of 10-15 rats were maintained as controls without prior treatment with MNNG. The incidences of squamous cell carcinoma of the forestomach in MNNG-treated animals were significantly elevated by the diets containing CC (P less than 0.001), 2-tert-butyl-4-methylphenol (P less than 0.001), or p-tert-butylphenol (P less than 0.01), while the development of carcinoma in situ was inhibited by 4MP (P less than 0.01). Treatment with CC, 2-tert-butyl-4-methylphenol, p-tert-butylphenol, or 4MP alone induced forestomach hyperplasia at incidences of 86.7, 40, 93.3, and 100%, respectively. In the pyloric region of the glandular stomach, the development of adenomatous hyperplasia and adenocarcinoma after MNNG treatment was significantly enhanced by diet containing CC (P less than 0.001). Moreover, treatment with CC alone induced 100% adenomatous hyperplasia and induced adenocarcinoma in 20% of animals. These results clearly demonstrated that while antioxidants causing proliferation in forestomach epithelium can markedly enhance carcinogenesis in this tissue, others displaying the same or greater potential for generating a hyperplastic response, like 4MP, can exert an inhibitory effect. In addition, it was shown that CC, which is widely present in our environment, is an unequivocal glandular stomach carcinogen also possessing strong enhancing activity for MNNG-induced lesion development.

Topics: Animals; Anisoles; Antioxidants; Butylated Hydroxytoluene; Carcinoma in Situ; Carcinoma, Squamous Cell; Catechols; Male; Methylnitronitrosoguanidine; Phenols; Rats; Rats, Inbred F344; Stomach Neoplasms

Following carcinogen exposure in vitro, normal rat tracheal epithelial cells are transformed in a multistage process in which the cultured cells become immortal and, ultimately, neoplastic. Five cell lines derived from tumors produced by neoplastically transformed rat tracheal epithelial cells were examined for the expression of 11 cellular oncogenes previously implicated in pulmonary or epithelial carcinogenesis. RNA homologous to fms was expressed at a level 5-19 times higher than normal tracheal epithelial cells in three of five of the tumor-derived lines. All three lines expressing high levels of fms-related RNA gave rise to invasive tumors of epithelial origin when injected into nude mice. Increased expression of the fms-related mRNA was not due to gene amplification, and no gene rearrangement was detected by Southern analyses. RNA blot analysis using a 3' v-fms probe detected a 9.5-kilobase message in the three tumor-derived lines, whereas both normal rat alveolar macrophages and the human choriocarcinoma line BeWo expressed a fms transcript of approximately 4 kilobases. We conclude from these data that the gene expressed as a 9.5-kilobase transcript in these neoplastic epithelial cells is a member of a fms-related gene family but may be distinct from the gene that encodes the macrophage colony-stimulating factor (CSF-1) receptor.

Topics: Animals; Base Sequence; Carcinoma, Squamous Cell; Cell Line; Cell Transformation, Neoplastic; Epithelium; Gamma Rays; Gene Amplification; Genes; Methylnitronitrosoguanidine; Oncogenes; Protein-Tyrosine Kinases; Rats; Trachea; Tracheal Neoplasms

The effect of exogenous synthetic prostaglandins and the inhibition of endogenous prostaglandin synthesis on gastrointestinal tumorigenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine [(MNNG) CAS: 70-25-7] was studied in female Wistar rats (100 g). Animals were divided into 6 groups: Group I was treated with MNNG alone (No. = 43); group II was treated with MNNG after application of the cyclo-oxygenase inhibitor flurbiprofen (No. = 44); group III was treated with MNNG after oral administration of 16,16-dimethyl-prostaglandin E2 (16,16-dm-PGE2; No. = 43); group IV received flurbiprofen alone (No. = 15); group V was treated with 16,16-dm-PGE2 alone (No. = 11). Animals in group VI served as controls (No. = 15). All drugs were administered orally. Hyperkeratosis and hyperplasia of the forestomach developed by 10 days after the first treatment with the carcinogen. Later, benign papillomas and dysplastic lesions were noted. Progressive ingrowth of squamous epithelium from the forestomach ridge into the glandular stomach started as early as day 13 and was more frequent in animals treated with a combination of MNNG plus flurbiprofen (P less than .001). The first squamous cell carcinomas of the forestomach were detected on day 51. Their incidence was 38, 60, and 42% in groups I, II, and III, respectively. This difference was not statistically significant. The incidence of mesenchymal tumors (leiomyosarcoma) in the stomach and duodenum was higher following treatment with MNNG plus flurbiprofen as compared to the incidence following treatment with MNNG alone or in combination with 16,16-dm-PGE2 (P less than .005). No malignant tumors developed in the gastrointestinal tracts of animals treated with flurbiprofen or 16,16-dm-PGE2 alone or in controls. The higher incidence of gastric and duodenal leiomyosarcomas after treatment with flurbiprofen suggests that reduction of prostaglandin synthesis favored the development of MNNG-induced cancer in mesenchymal tissues of the upper gastrointestinal tract.

Topics: Animals; Body Weight; Carcinoma, Squamous Cell; Female; Flurbiprofen; Gastric Acid; Gastrointestinal Neoplasms; Leiomyosarcoma; Methylnitronitrosoguanidine; Papilloma; Propionates; Prostaglandins E, Synthetic; Rats; Rats, Inbred Strains; Stomach Neoplasms

Topics: Animals; Carcinoma, Squamous Cell; Intubation, Gastrointestinal; Methylnitronitrosoguanidine; Mice; Papilloma; Stomach Neoplasms

Topics: Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Dogs; Dose-Response Relationship, Drug; Esophageal Neoplasms; Male; Methylnitronitrosoguanidine; Stomach Neoplasms

The incidence of metastasis was evaluated in female SENCAR mice after induction of squamous cell carcinomas by repetitive applications of either benzo [a] pyrene (B [a] P) or N-methyl-N'-nitro-N-nitrosogaunidine (MNNG). Between 41 and 50 weeks 50% of the animals with carcinomas in the B [a] P group had metastases, whereas 20% had metastases in the MNNG group. Very few metastases were observed before 40 weeks of treatment. The major site of metastasis was the lungs; however, metastatic tumors were also found in lymph nodes, adrenal glands and kidneys.

Topics: Animals; Carcinoma, Squamous Cell; Female; Methylnitronitrosoguanidine; Mice; Neoplasm Metastasis; Skin Neoplasms; Time Factors

Topics: Animals; Carcinoma, Squamous Cell; Digestive System Neoplasms; Female; Male; Methylnitronitrosoguanidine; Polysorbates; Rats; Stomach Neoplasms; Surface-Active Agents

Topics: Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Duodenal Neoplasms; Female; Intubation, Gastrointestinal; Jejunal Neoplasms; Male; Methylnitronitrosoguanidine; Mice; Papilloma; Stomach Neoplasms

Of 158 channel catfish (Ictalurus punctatus) exposed to N-methyl-N'-nitro-N-nitrosoguanidine [(MNNG) CAS:70-25-7] in water for 28 days, 2 developed disseminated lymphosarcoma. One fish was necropsied at 12 months and another at 18 months following exposure. Both fish had a massive neoplastic infiltration of the bilateral pairs of head and trunk kidneys from which the neoplastic cells appeared to originate. The neoplastic infiltration was also observed in the following: thymus, gills, oral mucosa, liver, skin, skeletal muscle of head-neck region, and to a lesser extent spleen and bone marrow. This is probably the first report of lymphosarcoma in channel catfish. Although the occurrence of lymphosarcoma in these 2 catfish appeared to be related to exposure to MNNG, the exact role MNNG played in the tumor formation was not determined.

Topics: Animals; Carcinoma; Carcinoma, Squamous Cell; Fish Diseases; Fishes; Kidney Neoplasms; Lipoma; Lymphoma, Non-Hodgkin; Methylnitronitrosoguanidine; Mouth Mucosa; Mouth Neoplasms; Papilloma; Water Pollutants, Chemical

In order to obtain a reliable experimental model simulating human esophageal cancer, endoscopic and histopathological studies were undertaken in the esophageal cancer produced in the beagle dog. Thirty-seven dogs had been given a solution of N-Ethyl-N'-nitro-N-nitrosoguanidine (ENNG) at a concentration of 150 micrograms/ml for 3-9 months. Follow-up studies included serial endoscopy and biopsy, and almost all animals were eventually sacrificed for histological examination. The results were as follows: Squamous cell carcinoma was observed in 5 out of 22 female dogs, while none in male dogs at all. For the induction of squamous cell carcinoma in the esophagus, administration in the condition of 150 micrograms/ml (75mg/day) for 6-9 months was most suitable. Almost all of esophageal lesions were protruding and well-differentiated squamous cell carcinoma with invasion of the submucosa. The stages of hyperplasia, dysplasia and squamous cell carcinoma in the esophagus were chronologically followed. Carcinoma had been observed in the stomach about 4 months prior to the appearance of esophageal carcinoma. This experimental model was proved to be useful for studies on histogenesis of human esophageal cancer both light and electron microscopically.

Topics: Animals; Carcinoma, Squamous Cell; Dogs; Esophageal Neoplasms; Female; Male; Methylnitronitrosoguanidine; Microscopy, Electron; Sex Factors; Stomach Neoplasms

Solution of N-methyl-N-nitrosourea (MNU), diazoacetic ester (DAAE), N-methyl-N-nitro-N-nitrosoguanidine (MNNG), N-methyl-N,N'-dinitroguanidine, 4-dimethylaminoazobenzene (DAB), o-aminoazotoluene or 7,12-dimethylbenz(a)anthracene (DMBA) were applied to rat skin. Neoplasms (skin tumors) were found only in the experiments with MNU, DAAE, MNNG, DAB and DMBA, MNU, MNNG, DAB and DMBA induced tumours in the sites of skin painting. In experiments with DAAE distant skin neoplasms developed as well. Possible mechanisms of action of these compounds are discussed.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinoma, Squamous Cell; Diazonium Compounds; Female; Keratoacanthoma; Male; Methylnitronitrosoguanidine; Methylnitrosourea; o-Aminoazotoluene; p-Dimethylaminoazobenzene; Papilloma; Rats; Skin Neoplasms

Albino rats (noninbred) were divided into 4 groups: 1) 56 control rats, 2) 40 rats fed 1 ml aspirin suspension (40 mg/ml) twice a week, 3) 20 rats given N-nitroso-N-methylnitroguanidine (MNNG) solution (250 micrograms/ml) to drink ad libitum, and 4) 40 rats given both aspirin and MNNG. In 18 months, there were no gastrointestinal tumors in groups 1 and 2, 8 cases of gastric tumors in group 3, and 37 cases of gastric tumors in group 4. Adenocarcinomas of the glandular stomach were found in 21 of 40 rats in group 4 but in only 4 of the 20 rats in group 3; the difference in incidence was significant. Histologic and electron microscopic examination of the epidermoid carcinomas and adenocarcinomas in group 4 showed no difference from such tumors induced by MNNG only. Hyperplasia of the forestomach mucosa and hyperplasia of the pyloric gland region of the glandular stomach in group 4 were more severe.

Topics: Adenocarcinoma; Animals; Aspirin; Carcinoma, Squamous Cell; Cocarcinogenesis; Female; Humans; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental; Papilloma; Probability; Rats; Stomach Neoplasms

The effect of histamine on induction of tumors in the forestomach and the glandular stomach after N-nitroso-N-methylnitroguanidine (MNNG) administration was studied in male inbred W rats. Animals were given 50 micrograms MNNG solution/ml orally for 25 weeks and then 4 mg histamine dihydrochloride sc per day in depot form. Administration of histamine in depot form after MNNG significantly increased the incidence of tumors in the forestomach, but it significantly decreased the incidence of adenocarcinomas in the glandular stomach. All of the tumors induced in the forestomach were of the squamous cell type, and 50% of them were squamous cell carcinomas. Histamine alone had no apparent carcinogenicity in rats.

Topics: Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Histamine; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental; Rats; Rats, Inbred Strains; Stomach Neoplasms

Two experiments were undertaken to induce uterine cancer in rats by intrauterine administration of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in a total of 120 inbred female ACI rats, 5 weeks old. In Experiment I, 55 rats were divided into 3 groups and given a single injection of MNNG 50 mg (Group 1) or 100 mg (Group 2)/kg body weight emulsified in olive oil or olive oil alone (Group 3) into the uterine canals after the laparotomy. Uterine corpus tumors including endometrial adenocarcinomas were developed in 35.3% (Group 1) and 16.7% (Group 2) of the effective animals. Endometrial adenomatous hyperplasia which was considered to be a precancerous lesion, was observed in a few rats of Group 2. No tumors nor hyperplastic lesions were seen in the control group. (The incidence of tumors in the uterine corpus was significantly higher in the animals of Group 1 or 2 than in those of Group 3 (P less than 0.05]. In Experiment II, 65 rats were divided into 4 groups and treated as follows; Group 1: Rats were given intravaginal detention of absorbent cottons dipped with 0.5 mg of MNNG dissolved in 0.2 ml of olive oil for a week. The treatment was repeated 20 times once every two weeks. Group 2: Animals were treated by intravaginal detention of cottons containing 10% acetic acid or MNNG in alternate weeks 5 times each, and then the detention of MNNG-cottons 15 times every other week. Group 3: Rats were given the absorbent cottons containing olive oil alone 20 times biweekly.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenocarcinoma; Administration, Topical; Animals; Carcinoma, Squamous Cell; Endometrium; Female; Hyperplasia; Methylnitronitrosoguanidine; Rats; Uterine Cervical Neoplasms; Uterine Neoplasms; Vaginal Neoplasms

Topics: Adenocarcinoma; Animals; Antioxidants; Ascorbic Acid; Carcinoma, Squamous Cell; Male; Methylnitronitrosoguanidine; Neoplasms; Rats; Rats, Inbred F344; Sarcoma; Stomach Neoplasms

The effect of vaccinia virus on MNNG-induced gastric cancer in rats was studied. Subcutaneous inoculation of the highly attenuated vaccinia virus AS strain at intervals of 3 days from the beginning of the experiment showed prominent antitumor activity not only against adenocarcinoma induced by MNNG in the glandular stomach but also against squamous cell carcinoma in the forestomach. Both UV-inactivated vaccinia virus and the DI strain of mammalian pathogenic vaccinia virus, from which the AS strain originated, showed no antitumor effect.

Topics: Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Male; Methylnitronitrosoguanidine; Rats; Rats, Inbred Strains; Stomach Neoplasms; Vaccines, Attenuated; Vaccinia virus; Viral Vaccines

After 12 oral applications of 80 mg/kg MNNG as a suspension in 30% aqueous ethanol at weekly intervals, 98 Sprague-Dawley rats died with multiple tumors of the forestomach after a medium latency period of 226 days. Histological examination showed generalized papillomatosis developing into keratinizing squamous cell carcinomas with infiltrative growth in 88/98 (89%) animals. Tumorigenic lesions in the glandular stomach ware only observed in 3/98 rats. In two of these animals, mucosal adenocarcinomas were found and in the third a leiomyosarcoma. In about 30% of the animals treated with MNNG, degenerative liver changes were found, especially single cell and focal necroses, cystic alterations, and bile-duct proliferations.

Topics: Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Leiomyosarcoma; Liver; Methylnitronitrosoguanidine; Neoplasms, Experimental; Papilloma; Rats; Rats, Inbred Strains; Stomach Neoplasms

Rats reveal distinct variations in response to carcinogenic action. The highest frequency of stomach tumors (69.6%) and the shortest period of their development (54.7 weeks) were registered in noninbred rats. Multiple lesions of the gastrointestinal tract were relatively frequent, too. Augustus and Penguin rats responded with a high frequency of tumor development. However, tumors arose in them later than in noninbred rats. Wistar rats appeared to be relatively resistant to MNNG action.

Topics: Adenocarcinoma; Adenoma; Animals; Carcinoma, Squamous Cell; Gastrointestinal Neoplasms; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental; Rats; Rats, Inbred Strains; Sarcoma, Experimental

Topics: Animals; Carcinogens; Carcinoma, Squamous Cell; Dogs; Epithelium; Esophageal Neoplasms; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental

In order to define factors which determine susceptibility to chemical carcinogenesis, mice sensitive (SENCAR) and resistant (BALB/c) to epidermal carcinogenesis were studied under several treatment conditions for sensitivity to initiation by 7,12-dimethylbenz(a)anthracene or N-methyl-N'-nitro-N-nitrosoguanidine and promotion by 12-O-tetradecanoylphorbol-13-acetate. In newborns of both strains, topical application of initiator was much less effective than in adults. However, initiation by i.p. injection of 7,12-dimethylbenz(a)anthracene is at least as effective in newborns as in adults, which may indicate that topically applied carcinogen is not delivered effectively to target cells in newborns. Thus, newborn epidermis can respond to 7,12-dimethylbenz(a)anthracene as well as adult epidermis when the initiator is appropriately administered. SENCAR mice are much more sensitive than are BALB/c mice to both initiators, which suggests that enhanced metabolic activation of hydrocarbon carcinogens by SENCAR mice is unlikely to account for their sensitivity. Newborn male SENCAR's developed approximately 50% more papillomas than did females in all groups. BALB/c newborn mice developed so few tumors that a meaningful comparison of sensitivity of males and females could not be made. Thus, the increased sensitivity of SENCAR's was apparent regardless of route of administration of initiator or the age or sex of the mice. SENCAR mice also developed a significant number of papillomas and squamous cell carcinomas with 12-O-tetradecanoylphorbol-13-acetate promotion in the absence of an exogenous initiator. Therefore, the skin of SENCAR mice may contain an initiated population of cells capable of responding to tumor promoters.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Age Factors; Animals; Benz(a)Anthracenes; Carcinoma, Squamous Cell; Cocarcinogenesis; Dose-Response Relationship, Drug; Methylnitronitrosoguanidine; Mice; Mice, Inbred Strains; Papilloma; Skin Neoplasms

Topics: Animals; Carcinoma, Squamous Cell; Dogs; Esophageal Neoplasms; Male; Methylnitronitrosoguanidine

Experimental colonic carcinoma in a dog was induced by anal insertion of an N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) suppository (each cone containing 50 mg of ENNG) for 17 months. The dog was autopsied 20 months after the initiation insertion of the suppository. Grossly, the colonic wall from the anus of the 10-cm oral side of the colon was thickened, and there was an infiltrating tumor with shallow depressions in the rough mucosa. The lymph node around this portion were enlarged, and white spots were found in the liver and redness in the lungs. Histological examination of the colon revealed a variety of pathologic features, e.g., undifferentiated carcinoma, squamous cell carcinoma and malignant melanoma in the region adjacent to the anus. Well and moderately differentiated adenocarcinomas involving the proper muscle layer were found in a region oral to these tumors and were accompanied by marked invasion of the blood vessels and lymphatic permeation. There were metastases to the liver, lungs and lymph nodes which corresponded to the gross findings, and also metastases to renal glomeruli. A well differentiated adenocarcinoma and signet ring cell carcinoma were evident in the gastric mucosa. This experimental model should be useful for studies related to colonic carcinoma in humans.

Topics: Adenocarcinoma; Animals; Carcinogens; Carcinoma; Carcinoma, Squamous Cell; Colon; Colonic Neoplasms; Dogs; Female; Melanoma; Methylnitronitrosoguanidine; Neoplasms, Experimental; Stomach; Stomach Neoplasms; Suppositories

Early changes in the esophageal mucosa of dogs induced by N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) were studied. Seven one-year-old beagle dogs were given a solution of 250 micrograms ENNG/ml to drink ad libitum for 4 months. Three different kinds of lesions (10 erosive carcinomas, 4 slightly elevated microcarcinomas and 19 leukoplakias) were recognized. These three kinds of lesions were not located adjacent to one another, and were surrounded by almost normal stratified squamous epithelium. The foci of the carcinomas revealed an abrupt transition to normal epithelium and were considered to have arisen abruptly from normal esophageal epithelium. The histogenesis of squamous cell carcinomas of the esophagus in dogs may differ from that in man.

Topics: Animals; Carcinoma; Carcinoma, Squamous Cell; Dogs; Esophageal Neoplasms; Leukoplakia; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental

Topics: Animals; Carcinoma, Squamous Cell; Eyelid Neoplasms; Female; Heart Neoplasms; Lethal Dose 50; Lung Neoplasms; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental; Rats

Topics: Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Cell Line; Cell Transformation, Neoplastic; Epithelium; Methylnitronitrosoguanidine; Neoplasms, Experimental; Rats; Time Factors; Tracheal Neoplasms

Laboratory-bred European hamsters received intragastric administrations of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) once weekly for 20 weeks. The animals showed mainly squamous cell papillomas and carcinomas of the fore-stomach. The tumour incidence was higher in males (80%) than in females (30%). The average tumour latency was comparatively short (25 weeks).

Topics: Animals; Carcinogens; Carcinoma, Squamous Cell; Cricetinae; Female; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental; Papilloma; Species Specificity; Stomach Neoplasms

When N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was orally intubated to conventional newborn rats by the catheter technique, the rats were found with tumors almost exclusively developed in the glandular stomach, mostly until 280 days after the first intubation. Tumor incidence was about 50% in both sexs of rats that survived the intubation of a single dose of MNNG in rats of less than 24 hr after birth and almost 100% in both sexes of rats that survived the intubation of three consecutive daily doses of MNNG on 5th day after birth. Out of 52 rats treated with MNNG, 40.4% developed carcinomas (20 adenocarcinomas and 1 squamous cell carcinoma), three of them having metastatic lesions. The predilective localization of tumors in the glandular, especially fundic, portion of the stomach, might be attributed to the use of newborns and to the catheter technique devised here.

Topics: Adenocarcinoma; Administration, Oral; Animals; Animals, Newborn; Carcinoma, Squamous Cell; Female; Leiomyosarcoma; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental; Rats; Stomach; Stomach Neoplasms

Three 6-month-old male beagle dogs were given a solution of 150 microng N-ethyl-N'-nitrosoguanidine (ENNG)/ml to drink ad libitum for 9 months. They all developed esophageal squamous cell carcinomas and gastric adenocarcinomas. The stomach adenocarcinomas were mostly in the antrum along the lesser curvature and were either well differentiated or poorly differentiated, with or without signet ring cells. The well-differentiated adenocarcinomas metastasized to the liver, and the poorly differentiated ones metastasized to the lymph nodes. The gastric mucosa in the antrum was atrophic, and the muscularis mucosae was fibrotic. Esophageal lesions were multicentric moderately differentiated squamous cell carcinomas, and they developed without diffuse hyperplastic changes of the epithelium. One dog with a large ulcerated carcinoma of the esophagus had metastases in the lung, liver, peritoneum, and abdominal lymph nodes. One dog also had a hemangiosarcoma with hepatic metastasis and spindle cell sarcoma in the stomach and duodenum, respectively.

Topics: Adenocarcinoma; Administration, Oral; Animals; Carcinoma, Squamous Cell; Dogs; Esophageal Neoplasms; Male; Methylnitronitrosoguanidine; Neoplasm Metastasis; Neoplasms, Experimental; Neoplasms, Multiple Primary; Stomach Neoplasms

Carcinogens injected into the excretory canal of submandibular gland of Donryu rats revealed the following histologic changes in salivary glands. 20-Methylcholanthrene induced squamous cell metaplasia, fibrosis in the early stages, and "benign lymphoepithelial lesion"-like pattern after 3 months. Dense hyalinization occurred after 4-5 months with so-called "mixed tumor"-like pattern. In the later stages epidermoid carcinoma and fibrosarcoma were observed. 9, 10-Dimethylbenzanthracene caused degenerative change, metaplasia, fibrosis and cell infiltration, and later carcinoma and sarcoma appeared at a high rate. 4-Nitroquinoline-N-oxide led to dense hyalinization and so-called "mixed tumor"-like pattern was observed in many specimens. N-nitroso-N-methyl urethane and N-methyl-N-nitroso-N'-nitroguanidine revealed metaplastic changes, fibrosis and lymphoid infiltration. Scarlet red induced remarkable infiltration and aggregation of lymphoid cells, showing benign "lymphoepithelial lesion"-like pattern.

Topics: 4-Nitroquinoline-1-oxide; 9,10-Dimethyl-1,2-benzanthracene; Adenoma, Pleomorphic; Animals; Carcinogens; Carcinoma, Squamous Cell; Coloring Agents; Fibrosarcoma; Hemangioma; Injections; Male; Methylcholanthrene; Methylnitronitrosoguanidine; Nitrosomethylurethane; Rats; Rhabdomyosarcoma; Salivary Gland Neoplasms; Salivary Glands; Submandibular Gland

Topics: Adenocarcinoma; Animals; Carcinoid Tumor; Carcinoma, Hepatocellular; Carcinoma, Squamous Cell; Duodenal Neoplasms; Female; Hyperplasia; Liver Neoplasms; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental; Nitrosoguanidines; Papilloma; Rats; Rodent Diseases; Stomach Neoplasms

The effects were studied of NaCl on the production of gastric carcinomas by N-methyl-N-nitro-N-nitrosoguanidine (MNNG) and by 4-nitroquinoline-1-oxide (NQO) in male Wistar rats. Nine groups of rats were treated as follows: Group 1 was given 50 mg MNNG/liter and 6 g NaCl solution/liter to drink and was fed a stock diet supplemented with 10% NaCl. Group 2 received 1 ml saturated NaCl once a week and 50 mg MNNG/liter to drink. Group 3 was treated with MNNG alone. Group 4 was given a solution of 1 mg NQO once a week and fed a stock diet supplemented with 10% NaCl. Group 5 received a solution of 1 mg NQO saturated with NaCl. Group 6 was given NQO alone. Groups 7 and 8 were given NaCl alone. Group 9 was untreated. Adenocarcinomas developed in the glandular stomach in group 2 at a significantly higher incidence than in group 3. Poorly differentiated adenocarcinomas of the glandular stomach were detected in only groups 1 and 2. One poorly differentiated adenocarcinoma metastasized to the lymph nodes. A high incidence of squamous cell carcinomas of the forestomach was found in groups 4 and 5. No malignant tumors were seen in groups 6-9. NaCl given alone had no apparent carcinogenicity in rats but, when administered with MNNG or NQO, it enhanced the carcinogenic effects of MNNG and NQO in the stomach.

Topics: 4-Nitroquinoline-1-oxide; Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Drug Synergism; Gastric Mucosa; Intestinal Neoplasms; Intestine, Small; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental; Nitroquinolines; Nitrosoguanidines; Papilloma; Rats; Sarcoma; Sodium Chloride; Stomach; Stomach Neoplasms