metallothionein and Precancerous-Conditions

Gastric cancer (GC) is a heterogeneous disease with molecular diversity between and within tumors; therefore, searching for altered genes within this cancer is mandatory to reach the proper individualized targeted therapy. Expressions of Metallothionein (MT) and p21 are not uniform in various types of cancers and their predictive value in GC is controversial. This study aimed to assess the role of MT and p21 in intestinal-type GC and some of its precursor lesions.. Immunohistochemical staining for MT and p21 was applied on paraffin blocks belonging to 30 GCs and 51 benign gastric lesions/precancerous lesions [33 chronic gastritis and 18 chronic gastritis with gastric intestinal metaplasia (GIM)]; 27 of them were associated with H. pylori infection.. MT expression was dramatically increased while p21 expression was dramatically decreased from chronic gastritis to GIM to GC. In precancerous lesions, H. pylori-positive cases had significantly higher MT expression and lower p21 expression compared to H. pylori-negative cases. In GCs, decreased expression of both MT and p21 was associated with high-grade and advanced-stage cancers.. Both MT and p21 may have a role in the development and progression of GC, and both proteins may be useful for selecting targeted therapy for GC patients.

Topics: Cyclin-Dependent Kinase Inhibitor p21; Gastric Mucosa; Gastritis; Helicobacter Infections; Helicobacter pylori; Humans; Metallothionein; Metaplasia; Precancerous Conditions; Stomach Neoplasms

Background: Chemoprevention refers to the use of specificnatural or synthetic chemical agents to suppress the\ development and progression to carcinoma. The purpose of this study was to assess the effect of aspirin, vitamin C\ or zinc on the metallothionein (MT) mRNA gene expression as well as MT protein content byimmunohistochemistry\ andradioimmunoassay (RIA) in 1, 2-dimethyl hydrazine (DMH) induced cancerous colonic tissuein rats. Methods:\ Rats were randomly divided into three groups, group 1 (aspirin), group 2 (vitamin C) group 3 (zinc), each of which\ was further sub divided into two groups and given subcutaneous injections of DMH (30 mg/kg body weight) twice a\ week for 3 months and sacrificed at either 4 months (A-precancer model) or at 6 months (B-cancer model).The control\ groups were administered 0.5 ml saline subcutaneously. All the 3 groups were simultaneouslyadministered aspirin,\ vitamin Cor zinc supplement respectively from the beginning till the end of the study. Results: It was observed that\ rats co-treated with aspirin, vitamin C or zinc resulted in a significant increase in the colonic MT mRNA expression in\ the precancer and cancer model as compared to the saline only controls. MT protein expression showed a 60%, 64%\ and 78% immunopositivity in the co-treated groups respectively.The mean MT content in the precancer and the cancer\ model was restored to near normal levels in all the three co-treated groups. Conclusion: These results suggest that\ co-administration of aspirin, vitamin C or zinc resulted in a significant increase in MT mRNA gene expression, MT\ protein expression and MT protein content which could possibly be one of the reasons for a chemo protective effect\ against progression to colonic cancer in a chemically induced DMH model in rat.Zinc supplement had a greater effect\ on metallothionein expression than aspirin or vitamin C.

Topics: 1,2-Dimethylhydrazine; Animals; Anti-Inflammatory Agents, Non-Steroidal; Ascorbic Acid; Aspirin; Colon; Colonic Neoplasms; Dietary Supplements; Metallothionein; Precancerous Conditions; Rats; Rats, Wistar; Trace Elements; Vitamins; Zinc

Light-at-night exposure enhances the risk of cancer. Colon cancer is among the most dangerous tumors affecting humankind. Physical exercise has shown positive effects against colon cancer. Here, we investigated whether pineal gland modulates antipreneoplastic effects of physical exercise in the colon. Surgical and non-surgical pineal impairments were performed to clarify the relationship between the pineal gland activity and manifestation of colonic preneoplastic lesions. Next, a progressive swimming training was applied in rats exposed or not to either non-surgical pineal impairment or carcinogen treatment for 10 weeks. Both surgical and non-surgical pineal impairments increased the development of colon preneoplasia. It was further found that impairing the pineal gland function, higher rates of DNA damage were induced in colonic epithelial and enteric glial cells. Physical exercise acted positively against preneoplasia, whereas impairing the pineal function with constant light exposure disrupts its positive effects on the development of preneoplastic lesions in the colon. This was yet related to increased DNA damage in glial cells and enteric neuronal activation aside from serum melatonin levels. Our findings suggest that protective effects of physical exercise against colon cancer are dependent on the pineal gland activity.

Topics: 1,2-Dimethylhydrazine; Animals; Colonic Neoplasms; Cyclooxygenase 2; DNA; DNA Damage; Enteric Nervous System; Light; Male; Melatonin; Metallothionein; Neuroglia; Neurons; Physical Conditioning, Animal; Pineal Gland; Precancerous Conditions; Proto-Oncogene Proteins c-fos; Rats; Rats, Wistar

We investigate and compare the possible antitumor activity of clinically used angiotensin converting enzyme (ACE) inhibitors; captopril, perindopril and angiotensin II type 1 receptor (AT1R) blocker, losartan against hepatocarcinogenesis initiated by diethylnitrosoamines (DENA) and promoted by carbon tetrachloride (CCl(4)).. Diethylnitrosamine (DENA) (200mg/kgi.p.) initiated and carbon tetrachloride (CCl(4)) (2ml/kgi.p.) promoted hepatocarcinogenesis in male Wistar rats after 8weeks.. Hepatocarcinogenesis was manifested biochemically by elevation of serum hepatic tumor markers tested; α-feto protein (AFP) and carcinoembryonic antigen (CEA). In addition, hepatic carcinogenesis was further confirmed by a significant increase in hepatic tissue growth factors; vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF). Moreover a marked increase in matrix metalloproteinase-2 and hydroxyproline content were also observed. Hepatocarcinogenesis was further confirmed by a significant decrease in hepatic endostatin and metallothonein level.. Long-term administration of the selected drugs for 2weeks before and throughout the experimental period produced a significant protection against hepatic carcinogenesis. The present results claimed that different doses of the selected drugs succeeded in normalization of serum tumor markers. Furthermore, the drugs reduced the elevated level in the hepatic growth factors, matrix metalloproteinase-2 and hydroxyproline induced by the hepatocarcinogen. Moreover, the amelioration was also accompanied by augmentation of hepatic content of metallothionein and endostatin. Histopathological examination of liver tissues of rats treated with DENA-CCl(4) correlated with the biochemical observations.. These findings suggest a similar protective effect of ACE inhibitors; captopril; perindopril and AT1R blocker, losartan against premalignant stages of liver cancer in the DENA initiated and CCl(4) promoted hepatocarcinogenesis model in rats. Therefore, RAS especially angiotensin II (Ang II) and AT1R interaction plays a pivotal role hepatocarcinogenesis development.

Topics: alpha-Fetoproteins; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Animals; Anticarcinogenic Agents; Captopril; Carcinoembryonic Antigen; Endostatins; Enzyme-Linked Immunosorbent Assay; Fibroblast Growth Factors; Hydroxyproline; Liver; Liver Neoplasms, Experimental; Losartan; Male; Matrix Metalloproteinase 2; Metallothionein; Perindopril; Precancerous Conditions; Rats; Transforming Growth Factor beta1; Vascular Endothelial Growth Factor A

Inorganic lead compounds are carcinogenic in animals and have carcinogenic potential in humans. In mice, lead (Pb) is a transplacental carcinogen in the kidney. Metallothionein (MT) is a metal-binding protein that can reduce the toxicity of various metals, including Pb, either by direct sequestration or as an antioxidant for metals that generate reactive oxygen species. Although MT appears to reduce Pb carcinogenicity in adult mice it is unknown how MT deficiency may affect Pb carcinogenicity from early life exposure. Thus, groups (n=10) of pregnant MT-I/II double knockout (MT-null) or 129/SVJ MT wild type (WT) mice were exposed to Pb acetate in the drinking water (0, 2000, 4000ppm Pb) from gestation day 8 through birth and during lactation. Maternal drinking water Pb exposure continued to wean at 4 weeks of age and the male offspring were then directly exposed to Pb until 8 weeks of age and observed until 2 years old. High dose (4000ppm) but not low dose (2000ppm) Pb reduced survival in the latter part of the study in both MT-null and WT mice. In MT-null mice, but not WT, early life Pb exposure caused a dose-related increase in testicular teratomas, to a maximum incidence of 28% compared to control (4%). Pb-induced renal cystic hyperplasia, considered preneoplastic, was a prominent occurrence in MT-null mice but nearly absent in WT mice. Pb dose-related increases in renal cystic hyperplasia occurred in adult MT-null with early life exposure with maximal incidence of 52%. Pb-treated MT-null mice also showed dose-related increases in urinary bladder hyperplasia with occasional papilloma that were absent in WT mice. Thus, MT deficiency made mice more sensitive to early life Pb exposure with regard to testes tumors, and renal and urinary bladder preneoplastic lesions.

Topics: Animals; Carcinogens, Environmental; Dose-Response Relationship, Drug; Female; Hyperplasia; Kidney Diseases, Cystic; Lead; Male; Maternal Exposure; Metallothionein; Mice; Mice, Knockout; Precancerous Conditions; Pregnancy; Prenatal Exposure Delayed Effects; Teratoma; Testicular Neoplasms; Urinary Bladder Diseases

Oral leukoplakia (OL) is the main potentially malignant lesion of the oral cavity, and oral squamous cell carcinoma (OSCC) accounts for more than 95% of all malignant neoplasms in the oral cavity. Therefore, the aim of this study was to verify the immunoexpression of p-Akt and Metallothionein (MT) proteins in dysplasic and neoplasic oral lesions.. Immunohistochemical studies were carried out on 10 normal epithelium, 30 OL and 15 OSCC paraffin-embedded samples. Immunoperoxidase reaction for p-Akt and MT proteins was applied on the specimens, and the positivity of the reactions was calculated for 1000 epithelial cells.. Using the ANOVA and the Tukey's post hoc statistical analyses, it was observed a significant difference in the immunoexpression for p-Akt and MT when the OSCC samples were compared with normal and dysplasic epithelial groups. In addition, the Pearson's correlation test showed a significant correlation between the proteins' expression.. Based on the data obtained, p-Akt and MT activation may play an important role in the conversion of a potentially malignant oral lesion to a malignant carcinoma since its earlier stages.

Topics: Adult; Analysis of Variance; Carcinoma, Squamous Cell; Case-Control Studies; Female; Humans; Leukoplakia, Oral; Male; Metallothionein; Middle Aged; Mouth Mucosa; Mouth Neoplasms; Precancerous Conditions; Proto-Oncogene Proteins c-akt; Reference Values; Second Messenger Systems; Signal Transduction; Statistics, Nonparametric

The incidence of esophageal squamous cell carcinoma (ESCC) is very high in northern China. This cancer has a very poor prognosis, mostly because it is usually diagnosed at a late stage. Detection at an earlier stage can dramatically improve prognosis. Microscopic evaluation of esophageal balloon cytology (EBC) specimens has been the most common method for early detection of ESCC, but this technique is limited by low sensitivity and specificity. The use of molecular markers may improve these screening characteristics. This study evaluates whether measurement of gene methylation in EBC specimens may have utility for the detection of esophageal squamous dysplasia and early ESCC. We evaluated the presence of methylation in eight genes shown to be methylated in ESCC in previous studies in EBC specimens from 147 patients with endoscopic biopsy diagnoses ranging from normal mucosa to severe squamous dysplasia. Methylation status was determined using quantitative methylation-specific PCR techniques. The sensitivity and specificity of methylation of each individual gene and of combinations of these genes to detect biopsyproven high-grade (moderate or severe) squamous dysplasia were determined. For individual genes, the sensitivities ranged from 9% to 34% and the specificities ranged from 77% to 99%. Using a panel of four genes (AHRR, p16INK4a, MT1G, and CLDN3) resulted in sensitivity and specificity of 50% and 68%, respectively. This study suggests that evaluation of gene methylation in EBC samples may have utility for early detection of esophageal squamous dysplasia and early ESCC; however, identification of more sensitive methylation markers will be required for development of a clinically useful screening test.

Topics: Adult; Aged; Barrett Esophagus; Basic Helix-Loop-Helix Transcription Factors; Biomarkers, Tumor; Carcinoma, Squamous Cell; Claudin-3; DNA Methylation; Early Detection of Cancer; Esophageal Neoplasms; Esophagoscopy; Female; Genes, p16; Humans; Male; Membrane Proteins; Metallothionein; Middle Aged; Precancerous Conditions; Promoter Regions, Genetic; Repressor Proteins; Sensitivity and Specificity

Carcinogenic risk and molecular mechanisms underlying the liver tumor-promoting activity of copper gluconate, an additive of functional foods, were investigated using a rat medium-term liver carcinogenicity bioassay protocol (Ito test) and a 2-week short-term administration experiment. In the medium-term liver bioassay, Fischer 344 male rats were given a single i.p. injection of N-nitrosodiethylamine at a dose of 200 mg/kg b.w. as a carcinogenic initiator. Starting 2 weeks thereafter, rats received 0, 10, 300 or 6,000 ppm of copper gluconate in diet for 6 weeks. All rats underwent 2/3 partial hepatectomy at the end of week 3, and all surviving rats were killed at the end of week 8. In the short-term experiment, rats were given 0, 10, 300 or 6,000 ppm of copper gluconate for 2 weeks. Numbers of glutathione S-transferase placental form (GST-P) positive lesions, single GST-P-positive hepatocytes and 8-oxoguanine-positive hepatocytes, and levels of cell proliferation and apoptosis in the liver were significantly increased by 6,000 ppm of copper gluconate in the medium-term liver bioassay. Furthermore, hepatic mRNA expression of genes relating to the metal metabolism, inflammation and apoptosis were elevated by 6,000 ppm of copper gluconate both in the medium-term liver bioassay and the short-term experiments. These results indicate that copper gluconate possesses carcinogenic risk toward the liver at the high dose level, and that oxidative stress and inflammatory and pro-apoptotic signaling statuses may participate in its underlying mechanisms.

Topics: Administration, Oral; Animals; Apoptosis; Biological Assay; Carcinogenicity Tests; Carcinogens; Cell Proliferation; Diet; Dose-Response Relationship, Drug; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Gluconates; Glutathione Transferase; Guanine; Hepatectomy; Hepatocytes; Liver; Liver Neoplasms; Male; Metallothionein; Metals; Oxidative Stress; Precancerous Conditions; Rats; Rats, Inbred F344; RNA, Messenger

Upper aerodigestive tract (UADT) cancer, including oral and esophageal cancer, is an important cause of cancer deaths worldwide. Patients with UADT cancer are frequently zinc deficient (ZD) and show a loss of function of the pivotal tumor suppressor gene p53. The present study examined whether zinc deficiency in collaboration with p53 insufficiency (p53+/-) promotes lingual and esophageal tumorigenesis in mice exposed to low doses of the carcinogen 4-nitroquinoline 1-oxide. In wild-type mice, ZD significantly increased the incidence of lingual and esophageal tumors from 0% in zinc sufficient (ZS) ZS:p53+/+ mice to approximately 40%. On the p53+/- background, ZD:p53+/- mice had significantly greater tumor incidence and multiplicity than ZS:p53+/- and ZD:p53+/+ mice, with a high frequency of progression to malignancy. Sixty-nine and 31% of ZD:p53+/- lingual and esophageal tumors, respectively, were squamous cell carcinoma versus 19 and 0% of ZS:p53+/- tumors (tongue, P = 0.003; esophagus, P = 0.005). Immunohistochemical analysis revealed that the increased cellular proliferation observed in preneoplastic lingual and esophageal lesions, as well as invasive carcinomas, was accompanied by overexpression of cytokeratin 14, cyclooxygenase-2 and metallothionein. In summary, a new UADT cancer model is developed in ZD:p53+/- mouse that recapitulates aspects of the human cancer and provides opportunities to probe the genetic changes intrinsic to UADT carcinogenesis and to test strategies for prevention and reversal of this deadly cancer.

Topics: 4-Nitroquinoline-1-oxide; Animals; Biomarkers, Tumor; Carcinogens; Cyclooxygenase 2; Disease Models, Animal; Esophageal Neoplasms; Female; Gene Expression; Genetic Predisposition to Disease; Immunohistochemistry; Keratin-14; Keratins; Male; Metallothionein; Mice; Mice, Mutant Strains; Precancerous Conditions; Tongue Neoplasms; Tumor Suppressor Protein p53; Zinc

Metallothionein is a low-molecular-weight cysteine-rich protein that has the ability to bind and sequestrate heavy metal ions. It is associated with metalloregulatory functions such as cell proliferation, growth and differentiation.. To investigate the expression of metallothionein in hyperplastic, dysplastic and neoplastic prostatic lesions and to correlate its expression with histological grade of prostatic carcinoma.. The study was carried out on formalin-fixed and paraffin-wax-embedded tissue blocks from 8 patients with benign prostatic hyperplasia, 6 patients with prostatic intraepithelial neoplasia (PIN) and 30 patients with prostatic carcinoma, using the streptavidin-biotin technique. The histological grade was defined and the carcinomas were divided into low-grade (Gleason Score 2-4), 12 moderate grade (Gleason Score 5-6) and 10 high-grade (Gleason Score 7-10) carcinomas.. Patchy metallothionein staining of epithelial cells was observed in normal and benign prostatic tissues. All cases of PIN and 20 of 30 patients with prostatic carcinoma showed positive staining for metallothionein. Metallothionein expression considerably increased from low-grade to high-grade tumours. The proportion of cells staining positively for metallothionein was directly correlated with histological grade of prostatic carcinoma. The epithelial cells lack uniformity in staining intensity, but the percentage of strongly positive cells increased with the histological grade of prostatic carcinoma.. The high incidence of metallothionein expression in PIN in our study suggests that it is associated with early prostate tumorigenesis. Also, metallothionein expression was directly correlated with the histological grade of prostatic carcinoma, suggesting that metallothionein may be a useful marker for predicting the prognosis of prostate cancer.

Topics: Biomarkers, Tumor; Disease Progression; Humans; Male; Metallothionein; Neoplasm Proteins; Precancerous Conditions; Prognosis; Prostatic Hyperplasia; Prostatic Intraepithelial Neoplasia; Prostatic Neoplasms; Protein Isoforms

Esophageal squamous cell carcinoma (ESCC) is a common cancer with a very poor prognosis. New methods are needed to screen high-risk populations and identify curable tumors and precursor lesions early. Molecular markers may be useful in such screening efforts. This study was designed to determine the prevalence of p16, MGMT, RARbeta2, CLDN3, CRBP and MT1G gene methylation in patients with ESCC to evaluate the variation of gene methylation across a spectrum of preneoplastic lesions, and assess the feasibility of using gene methylation in a primary screening test utilizing frozen esophageal cells collected by balloon cytology samplers. Samples were obtained from high-risk subjects from north central China. These samples included 11 foci of histologically normal mucosa, 8 foci of low-grade squamous dysplasia, 7 foci of high-grade squamous dysplasia, and 13 foci of ESCC from 6 fully embedded resection specimens; endoscopic biopsies from 6 individuals with no histological evidence of disease; and frozen esophageal balloon samples from 12 asymptomatic subjects. Promoter CpG site-specific hypermethylation status was determined for each gene using real-time methylation-specific PCR (qMS-PCR) based on Taqman chemistry. Of the 6 ESCC patients, 5 showed methylation of at least one gene. For most genes, methylation occurred with increasing frequency during neoplastic progression, with the largest increase found between low- and high-grade dysplasia. There was considerable variation in methylation patterns among different foci of the same histological grade, even within individual patients, but 16/20 (80%) of high-grade dysplastic and cancer foci had >or= 2 methylated genes, while 17/19 (89%) of normal and low-grade dysplastic foci had <2 methylated genes. These genes were rarely methylated in histologically normal mucosa from patients with or without ESCC. Gene methylation was common and easily detectable in the frozen esophageal cells collected by balloon cytology samplers. Our data suggest that methylation of p16, MGMT, RARbeta2, CLDN3, CRBP, and MT1G is common in the esophageal mucosa of patients with ESCC in this high-risk population, and tends to increase in prevalence in foci with increasing histological severity of disease. Methylation data from panels of genes may be able to identify patients with high-grade lesions. Balloon cytology may be able to screen the length of the esophagus effectively for a subset of cells with abnormal methylation, and may be useful

Topics: Adult; Aged; Carcinoma, Squamous Cell; Claudin-3; DNA Methylation; DNA Modification Methylases; DNA Repair Enzymes; Esophageal Neoplasms; Female; Genes, p16; Humans; Male; Membrane Proteins; Metallothionein; Middle Aged; Precancerous Conditions; Receptors, Retinoic Acid; Retinol-Binding Proteins; Retinol-Binding Proteins, Cellular; Tumor Suppressor Protein p14ARF; Tumor Suppressor Proteins

Our previous studies have shown that vanadium, a dietary micronutrient, has an inhibitory effect against experimentally induced rat hepatocarcinogenesis. In this study, we evaluated the role of vanadium on some potential protein expression markers of carcinogenesis, such as metallothionein (MT), an intracellular metal-binding protein linked with cell proliferation and apoptosis, Ki-67 nuclear antigen, and p53 tumor suppressor during 2-acetylaminofluorene (2-AAF)-induced (0.05% in basal diet) rat liver preneoplasia. In a short-term regimen, supplementation of vanadium at a dose of 0.5 ppm effectively suppressed the formation of DNA 'comets' (29.55%; P < 0.02), thereby indicating its nongenotoxicity at this particular dose. Vanadium administration throughout the study reduced relative liver weight (RLW), nodular incidence (57.15%), total number, and multiplicity (48.45%) with restoration of hepatic zinc (Zn), magnesium (Mg), selenium (Se), copper (Cu), iron (Fe), and calcium (Ca) contents when compared to the carcinogen control. Moreover, treatment with vanadium significantly abated the expressions of MT and Ki-67, studied at four sequential time points. An increased immunopositivity of p53 protein (1.03 +/- 0.23%; P < 0.02) was found in vanadium-treated rat liver with an elevated apoptotic-labeling index (AI; P < 0.001) as documented by TUNEL assay. Furthermore, a positive correlation between MT expression and Ki-67 labeling along with a strong negative correlation between MT immunoreactivity and AI (r = -0.9000, P = 0.0004 at week 24) at various time intervals suggest that, vanadium-mediated suppression of MT and Ki-67 expressions may be associated with induction of apoptosis. The results thus provide evidence for the first time in support of the potential role of vanadium on induction of p53 and apoptosis with concurrent suppression of MT and Ki-67 in order to have an understanding, in part, of the chemopreventive mechanism of this trace element in limiting neoplastic transformation in a defined model of experimental rat hepatocarcinogenesis.

Topics: 2-Acetylaminofluorene; Animals; Apoptosis; Body Weight; DNA Damage; Gene Expression Regulation; Ki-67 Antigen; Liver; Male; Metallothionein; Metals; Organ Size; Precancerous Conditions; Rats; Rats, Sprague-Dawley; Tumor Suppressor Protein p53; Vanadium

Zinc deficiency in rats enhances esophageal cell proliferation, causes alteration in gene expression, and promotes esophageal carcinogenesis. Zinc replenishment rapidly induces apoptosis in the esophageal epithelium thereby reversing cell proliferation and carcinogenesis. To identify zinc-responsive genes responsible for these divergent effects, we did oligonucleotide array-based gene expression profiling analyses in the precancerous zinc-deficient esophagus and in zinc-replenished esophagi after treatment with intragastric zinc compared with zinc-sufficient esophagi. Thirty-three genes (21 up-regulated and 12 down-regulated) showed a > or = 2-fold change in expression in the hyperplastic zinc-deficient versus zinc-sufficient esophageal epithelia. Expression of genes involved in cell division, survival, adhesion, and tumorigenesis were markedly changed. The zinc-sensitive gene metallothionein-1 (MT-1 was up-regulated 7-fold, the opposite of results for small intestine and liver under zinc-deficient conditions. Keratin 14 (KRT14, a biomarker in esophageal tumorigenesis), carbonic anhydrase II (CAII, a regulator of acid-base homeostasis), and cyclin B were up-regulated >4-fold. Immunohistochemistry showed that metallothionein and keratin 14 proteins were overexpressed in zinc-deficient esophagus, as well as in lingual and esophageal squamous cell carcinoma from carcinogen-treated rats, emphasizing their roles in carcinogenesis. Calponin 1 (CNN1, an actin cross-linking regulator) was down-regulated 0.2-fold. Within hours after oral zinc treatment, the abnormal expression of 29 of 33 genes returned to near zinc-sufficient levels, accompanied by reversal of the precancerous phenotype. Thus, we have identified new molecular markers in precancerous esophagus and showed their restoration by zinc replenishment, providing insights into the interaction between zinc and gene expression in esophageal cancer development and prevention.

Topics: 4-Nitroquinoline-1-oxide; Animals; Carcinoma, Squamous Cell; Esophageal Neoplasms; Gene Expression Regulation, Neoplastic; Immunohistochemistry; Keratin-14; Keratins; Male; Metallothionein; Precancerous Conditions; Rats; Reverse Transcriptase Polymerase Chain Reaction; Up-Regulation; Zinc

Insulin-like growth factor binding protein-1 (IGFBP-1) is synthesized in the liver and regulates the mitogenic effects of the insulin-like growth factors (IGFs). The evidence that IGFBP-1 plays a role in hepatocarcinogenesis, however, is equivocal. We have, therefore, investigated the development of preneoplastic hepatic lesions in transgenic mice in which the human IGFBP-1 gene is under the control of the mouse metallothionein promoter. The lesions were induced by treating 15-d-old male mice with a single intraperitoneal injection of 5 mg/kg diethylnitrosamine (DENA). Lesions were scored when the mice were 28 wk of age. Quantitative microscopy of liver sections revealed that significantly fewer transgenic mice treated with zinc to activate the transgene had focal lesions compared to either transgenic mice not treated with zinc or wild-type mice treated with zinc (36.4% versus 85.7% and 83.3%, respectively, P < 0.05 in each case). Zinc-treated transgenic mice also had significantly fewer lesions per liver (11.5 +/- 5.0 versus 74.7 +/- 18.4 and 59.4 +/- 15.6, respectively, P < 0.01 in each case) and a smaller percentage of liver volume occupied by lesions (0.2 +/- 0.1 versus 1.4 +/- 0.3 and 1.1 +/- 0.4 respectively, P < 0.05 in each case). Immunohistochemical staining showed that both IGF-I and IGF-II were overexpressed in most of the lesions. These results show that expression of the IGFBP-1 transgene leads to a marked inhibition of hepatic preneoplasia, possibly by decreasing the mitogenic activity of IGF-I and/or IGF-II. This study adds new evidence to the notion that the IGF axis plays an important role in liver cancer development.

Topics: Animals; Animals, Newborn; Body Weight; Carcinogens; Diethylnitrosamine; Gene Expression Regulation; Humans; Insulin-Like Growth Factor Binding Protein 1; Liver; Liver Neoplasms; Male; Metallothionein; Mice; Mice, Inbred C57BL; Mice, Transgenic; Organ Size; Precancerous Conditions; Promoter Regions, Genetic; Zinc

Metallothionein (MT) is expressed in various types of human tumors, including transitional cell carcinomas of the urinary bladder, but its biological significance remains unclear. In the present study, the role of MT in urinary bladder carcinogenesis induced by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) treatment was investigated using C57BL/6 mice. One hundred 5-week-old male C57BL/6 mice were divided into two groups, which were given drinking water with or without 0.05% BBN throughout the experimental period. Subgroups of ten animals from each group were sacrificed at weeks 5, 10, 15, 20 and 25, and urinary bladder samples were examined immunohistochemically for MT, proliferating cell nuclear antigen (PCNA) and apoptosis. MT was found to be abundant in normal-looking mucosa, but decreased with progression from precancerous lesions to invasive carcinoma in the urinary bladder obtained from BBN-treated mice. Lesions could be divided into MT-positive and negative. There was a tendency for greater MT expression in PCNA-positive lesions, while apoptosis was rather associated with MT-negativity. These data suggest that the overexpression of MT may play a role in mouse urinary bladder carcinogenesis.

Topics: Animals; Apoptosis; Butylhydroxybutylnitrosamine; Carcinogens; Immunohistochemistry; Male; Metallothionein; Mice; Mice, Inbred C57BL; Precancerous Conditions; Proliferating Cell Nuclear Antigen; Urinary Bladder; Urinary Bladder Neoplasms

To investigate the expression of MT1F gene in hepatocellular carcinoma tissue and the growth suppression effect of exogenous introduction of MT1F gene on liver cell line HepG2 and to explore the potential application of MT1F gene in gene therapy of tumor. Eukaryotic expression vector of pCMV-MT1F plasmid was introduced into HepG2 line which expressed no MT1F protein originally with lipofectamine transfection method. The cell growth curve, soft agar colony formation rate and tumorigenicity in SCID mice were examined to demonstrate the growth suppression effect of exogenous MT1F gene on HepG2 cell line. The MT1F mRNA and MT1F protein were also detected in 60 pairs of surgical specimens of hepatocellular carcinoma by in situ hybridization and immunohistochemistry. The transfected HepG2 cell line grew more slowly than control HepG2 as shown by cell growth curves, the soft agar colony formation rate (3.8 percent vs. 7.4 percent, p <.01) and the average growth rate of tumor in SCID mice (30.9 +/- 6.9 vs. 70.3 +/- 5.6, p <.01). The expression level of MT1F mRNA and protein significantly increased in paracancerous tissue, normal tissue than in cancer tissues (75 percent, 70 percent vs. 16.7 percent by ISH and 66.7 percent, 60 percent vs. 10 percent by IHC, p <.01). Exogenous MT1F gene shows the strong effect of growth inhibition on HepG2 cell line. In the liver cancer tissue, MT1F shows down-regulated expression that supports the inhibited function of MT1F in cancer growth and suggests MT1F may have an important role in gene therapy of hepatocellular carcinoma.

Topics: Animals; Blotting, Western; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Cell Transformation, Neoplastic; Genetic Vectors; Humans; Immunohistochemistry; Metallothionein; Mice; Mice, SCID; Neoplasm Transplantation; Plasmids; Precancerous Conditions; RNA, Messenger; Transfection

The potential of the metal-binding protein, metallothionein, in assessing the progression of normal oesophagus through Barrett's to adenocarcinoma was investigated. Metallothionein was quantitatively determined in resected tissues from patients undergoing oesophagectomy for high grade dysplasia/adenocarcinoma and in biopsies from patients with Barrett's syndrome. In 10 cancer patients, metallothionein concentrations in adenocarcinoma were not significantly different from normal oesophagus, although six had elevated metallothionein concentrations in the metaplastic tissue bordering the adenocarcinoma. In 17 out of 20 non-cancer patients with Barrett's epithelium, metallothionein was significantly increased by 108% (P<0.004). There was no association between the metallothionein levels in Barrett's epithelium and the presence of inflammatory cells, metaplasia or dysplasia. Metallothionein is a marker of progression from normal to Barrett's epithelium but is not increased in oesophageal adenocarcinoma.

Topics: Adenocarcinoma; Adult; Aged; Barrett Esophagus; Biomarkers; Biomarkers, Tumor; Biopsy; Disease Progression; Esophageal Neoplasms; Esophagitis; Esophagus; Female; Gastroesophageal Reflux; Humans; Hyperplasia; Male; Metallothionein; Metaplasia; Middle Aged; Neoplasm Metastasis; Neoplasm Proteins; Precancerous Conditions

Metallothioneins (MTs) are zinc-binding proteins whose overexpression may lead to sequestration of zinc ions and consequently to functional inactivation of the p53 tumor suppressor gene. The aim of the study was to investigate the potential role of MTs in the carcinogenesis of ulcerative colitis (UC) as well as possible effects on p53 function. The monoclonal antibodies E9 (anti-MT), DO-7, and 1801 (anti-p53) and the polyclonal antibody CM-1 (anti-p53) were used to stain formalin-fixed, paraffin-embedded colon specimens obtained from 14 patients with UC-associated colorectal carcinoma (CAC), 13 with high-grade dysplasia (HGD), 10 with low-grade dysplasia (LGD), and 30 with UC without dysplasia or carcinoma. Statistical significance (p <0.05) was assessed using Fisher's exact test. Positive MT staining (> 20% of tumor, dysplastic, or epithelial cells) was found in most UC and LGD but in only a small percentage of HGD and CAC (p <0.01 for CAC vs. UC and LGD vs. HGD). Positive p53 immunoreactivity was observed predominantly in HGD and CAC but not in LGD and UC (p <0.01 for CAC vs. UC and HGD vs. LGD). In histologically normal tissue neighboring CAC, significant MT expression was found in six of seven specimens with simultaneous lack of p53 expression. MT overexpression may represent an important early step in the development of CAC independent of p53 expression and should be investigated in the long term as an independent cancer risk factor in UC.

Topics: Adenocarcinoma; Adult; Aged; Biomarkers; Cell Transformation, Neoplastic; Colitis, Ulcerative; Colorectal Neoplasms; Humans; Immunohistochemistry; Metallothionein; Middle Aged; Precancerous Conditions; Risk Factors; Tumor Suppressor Protein p53

Epidermal changes overlying dermatofibromas (DFs) have been described as ranging from psoriasiform simple hyperplasia to basaloid hyperplasia sometimes morphologically indistinguishable from superficial basal cell carcinoma (BCC). To characterize epidermal hyperplasia overlying DFs and to determine its association with the disease process, we examined 30 cases of DF showing hyperplastic epidermis. We used nine immunohistochemical markers associated with keratinocyte proliferation or differentiation. In DFs, the dermal metallothionein (MT) expression and immunophenotypic changes with regard to epidermal differentiation varied depending on the stage of lesional evolution of the DFs. Immunostaining for epidermal growth factor receptor (EGFR), MT, and keratin 6 (K6) increased in simple hyperplastic epidermis (SHE) overlying DFs (n = 11), whereas it gradually diminished in basaloid hyperplastic epidermis (BHE) overlying DFs (n = 19). In SHE, there was a significant increase in K14 expression. Among 19 BHE cases, 12 showed premature expression of involucrin and delayed appearance of K1 along with aberrant expression of K14. Conversely, the remaining 7 BHE cases showed a pattern of involucrin and K1 similar to that of normal skin coinciding with decreased or absent dermal MT expression. Loricrin and filaggrin expression in all DFs was the same as that of normal skin. Based on the sparse positivity of Ki-67 in the hyperplastic epidermis overlying DFs, we found that the biologic ability of BHE and SHE was not apparent in the hyperproliferative state observed in psoriasis and BCC. These results suggest that the dermal fibrohistiocytic process may trigger the induction of SHE overlying DFs by an unknown mechanism and then mediate both the abnormal keratinocyte differentiation and the transformation of SHE to BHE through the evolution of the dermal lesions.

Topics: Biomarkers; Carcinoma, Basal Cell; Cell Differentiation; Cell Division; Epidermis; ErbB Receptors; Filaggrin Proteins; Histiocytoma, Benign Fibrous; Humans; Hyperplasia; Immunoenzyme Techniques; Keratinocytes; Keratins; Metallothionein; Precancerous Conditions; Psoriasis; Skin Neoplasms

Oxidative damage has long been related to carcinogenesis in human cancers and animal cancer models. Recently a rat esophageal adenocarcinoma (EAC) model was established in our laboratory by using esophagoduodenal anastomosis (EDA) plus iron supplementation. Our previous study suggested that iron supplementation enhanced inflammation and the production of reactive nitrogen species in the esophageal epithelium, which could contribute to esophageal adenocarcinogenesis. Here we further characterized oxidative damage in this model. We were particularly interested in how excess iron was deposited in the esophagus, and which cells were targeted by oxidative damage. Male Sprague-Dawley rats received iron supplementation (50 mg Fe/kg/month, i.p.) starting 4 weeks after EDA. The animals were killed at 11, 30 or 35 weeks after surgery. EAC appeared as early as week 11 after surgery, and increased over time, up to 60% at 35 weeks after surgery. All EACs were well-differentiated mucinous adenocarcinoma at the squamocolumnar junction. Iron deposition was found at the squamocolumnar junction and in the area with esophagitis. Esophageal iron overload could result from transient increase of blood iron after i.p. injection, and the overexpression of transferrin receptor in the premalignant columnar-lined esophagus (CLE) cells. Oxidative damage to DNA (8-hydroxy-2'-deoxyguanosine), protein (carbonyl content) and lipid (thiobarbituric acid reactive substance) in the esophagus was significantly higher than that of the non-operated control. CLE cells were believed to be the target cells of oxidative damage because they overexpressed heme oxygenase 1 and metallothionein, both known to be responsive to oxidative damage. We propose that oxidative damage plays an important role in the formation of EAC in the EDA model, and a similar situation may occur in humans with gastroesophageal reflux and iron over-nutrition.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma, Mucinous; Anastomosis, Surgical; Animals; Barrett Esophagus; Cocarcinogenesis; Deoxyguanosine; Disease Models, Animal; DNA Adducts; Duodenum; Epithelial Cells; Esophageal Neoplasms; Esophagitis; Esophagus; Gastroesophageal Reflux; Heme Oxygenase (Decyclizing); Humans; Iron; Isoenzymes; Male; Metallothionein; Oxidative Stress; Postoperative Complications; Precancerous Conditions; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Receptors, Transferrin; Thiobarbituric Acid Reactive Substances

Differential display is a valuable tool for the identification of differentially expressed genes in human carcinogenesis and development. The search for differentially expressed genes in gastric cancer and its premalignant lesions may help to define molecular alterations in the gastric mucosa that may precede the development of gastric cancer. Using the differential display technique, we identified a cDNA fragment, encoding metallothionein (MT) IIa mRNA. We performed immunohistochemical analysis using a monoclonal antibody directed against human MT and tissues obtained from 34 patients with gastric cancer and 20 healthy individuals to determine the expression and localization of MT in gastric cancer and its associated premalignant lesions and to correlate our findings with histomorphological features and Helicobacter pylori status. In addition, MT expression was assessed in gastric tissues obtained from patients with gastric cancer and first-degree relatives of patients with gastric cancers and healthy individuals using reverse transcription-PCR analysis. Northern blot analysis confirmed the overexpression of MT IIa in gastric cancer. In the normal gastric tissues, no MT immunoreactivity was observed at the superficial gastric epithelium toward the top of gastric glands. However, MT immunoreactivity was detected at the foveolar neck of the gastric glands. Immunohistochemical analysis revealed an intense MT immunoreactivity in gastric cancer cells, independent of tumor stage, grade of differentiation, or tumor type. Furthermore, areas of dysplasia and intestinal metaplasia also exhibited intense MT immunoreactivity. Reverse transcription-PCR analysis of gastric biopsies obtained from first-degree relatives of patients with gastric cancer revealed the frequent expression of MT Ia in this high-risk group as compared with healthy subjects (P < 0.01). The overexpression of MT in gastric cancer and the expression of MT in intestinal metaplasia and dysplasia, as well as the expression of MT in the gastric mucosa of first-degree relatives of patients with gastric cancer, point to a role for MT in the early process of malignant transformation of the gastric mucosa.

Topics: Adult; Aged; Aged, 80 and over; Antibodies, Monoclonal; Female; Gastric Mucosa; Humans; Intestinal Neoplasms; Male; Metallothionein; Metaplasia; Middle Aged; Precancerous Conditions; Reference Values; Reverse Transcriptase Polymerase Chain Reaction; Stomach Neoplasms

Previous work has shown that phenobarbital (PB) can promote cell survival in double transgenic c-myc/transforming growth factor (TGF)-alpha mice. This was achieved through a suppression of cell death brought about, at least in part, by a general increase in the level of bcl-2 protein and a decrease in TGF-beta1 in treated versus untreated animals. No changes were found in TGF-beta type II receptor or in bcl-X(L) protein levels. In the present work, we followed these animals for up to 31 wk of age (28 wk of treatment), by which time numerous tumors could be observed. A PB-dependent decrease in tumor latency and a significant increase in multiplicity were seen. No statistically significant changes in the phenotype of foci, nodules, or neoplasms were observed after PB administration, and no effect on median tumor size was detected. Levels of the anti-apoptotic protein bcl-2 did not correlate with tumor formation in PB-treated animals. However, in untreated mice, bcl-2 was higher in tumors than in surrounding tissue in all tumors examined. We believe that the PB-dependent modification of tumorigenesis in the livers of c-myc/TGF-alpha mice was predominantly a result of the ability of this drug to block cell death during the early stages of tumor development. The effect of PB was exerted apparently by a pathway similar to, but separate from, that of TGF-alpha. However, these pathways appear to converge downstream, having common effectors in the form of bcl-2 family proteins. Mol. Carcinog. 28:168-173, 2000.

Topics: Animals; Apoptosis; bcl-X Protein; Carcinogens; Cell Transformation, Neoplastic; Crosses, Genetic; Genes, myc; Genes, Synthetic; Genetic Predisposition to Disease; Humans; Liver Neoplasms, Experimental; Metallothionein; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Mice, Transgenic; Neoplasm Proteins; Phenobarbital; Precancerous Conditions; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-myc; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta; Transforming Growth Factor alpha; Transgenes

Metallothionein (MT) is inducible by various stimuli such as metals and physiological stress. Although elevated MT expression in certain type of tumors has been reported, there are few data available on the roles of MT in tumor formation. In this study, we immunohistochemically examined MT expression in gluthathione S-transferase placental type p (GST-P)-positive preneoplastic liver lesions induced by a chemical carcinogen and further examined the relationship between MT expression and the proliferative activity of the preneoplastic cells, using bromodeoxyuridine (BrdU) labeling indices. Eleven male Fischer rats (F344/DuCrj, 9 weeks old) were subjected to the Solt-Farber protocol. Thereafter, the livers were removed, frozen and sectioned serially for immunohistochemical staining of MT and GST-P. Eight rats were given six injections of BrdU before sacrifice. In 92.8% of GST-P positive lesions, high MT staining intensity was demonstrated. On the other hand, there was no correlation between the intensity of MT staining and the BrdU labeling indices of the preneoplastic lesions. Our results indicate that MT is a useful positive marker for preneoplastic liver lesions, though the reason why MT is expressed in the preneoplastic and neoplastic lesions remains to be elucidated.

Topics: 2-Acetylaminofluorene; Animals; Diethylnitrosamine; Glutathione Transferase; Liver Neoplasms; Liver Neoplasms, Experimental; Male; Metallothionein; Mutagens; Precancerous Conditions; Rats; Rats, Inbred F344

In this study we evaluated the immunohistochemical expression of metallothionein (MT) in 44 squamous cell carcinomas, 14 cases of in situ carcinoma, 47 with epithelial dysplasia, 11 papillomas and 21 cases of keratosis. The MT expression was studied in correlation with p53 protein expression and the proliferative cell nuclear antigen (PCNA). The monoclonal antibodies E9 (anti-MT), DO-7 (which reacts with a denaturation-resistant epitope in wild-type and mutant p53) and PC10 (anti-PCNA) on formalin-fixed, paraffin-embedded tissue were used employing the immunoperoxidase (ABC) method. The immunohistochemical localization of MT has shown its rather ubiquitous presence in the cytoplasm and nucleus of both benign and malignant epithelial cells. In most cases the adjacent "normal" epithelium showed low positivity in the basal portion. The mean value of metallothionein expression was 35.73 in squamous cell carcinomas, 32.21 in in situ carcinomas, 11.86 in dysplastic epithelium, 5.10 in papillomas and 3.5 in keratosis. In carcinomas, low MT expression (< 10% of neoplastic cells) was observed in 20.5% of the cases, moderate (10%-50% of neoplastic cells) in 54.5% and extensive expression (> 50% of neoplastic cells) in 25% of the cases. We did not find any statistically significant difference of MT expression between in situ and infiltrating carcinomas, while we did observe a significant difference between carcinomas and the other groups. There was a statistically significant difference in the PCNA values in both benign and malignant lesions, while no statistically significant difference was observed in p53 protein expression in the above groups. A positive correlation between MT expression and the PCNA value (p < 0.0001) in the benign and malignant groups was detected. The PCNA value was also correlated with the p53 protein expression (p = 0.001). No correlation was found between MT and p53 protein expression. In conclusion, these results suggest that the MT expression may play a role in the development of malignant disease of the larynx, from the early phase of laryngeal carcinogenesis, independently from the p53 expression. It is also possible to contribute to tumour cell growth, as determined by the PCNA score.

Topics: Adult; Aged; Aged, 80 and over; Carcinoma in Situ; Carcinoma, Squamous Cell; Epithelial Cells; Female; Humans; Immunoenzyme Techniques; Keratosis; Laryngeal Neoplasms; Male; Metallothionein; Middle Aged; Papilloma; Precancerous Conditions; Proliferating Cell Nuclear Antigen; Tumor Suppressor Protein p53

The PML-RAR alpha hybrid protein generated by the t(15;17) translocation in acute promyelocytic leukemia (APL) is thought to play a central role in the oncogenic process. However, analysis of the oncogenic activity of the fusion protein in tissue culture assays or in mice has been hampered by its apparent toxicity in multiple murine cells. To circumvent this problem, we generated an inducible line of transgenic mice, MT135, in which the expression of PML-RAR alpha is driven by the metallothionein promoter. After 5 days zinc stimulation, 27 out of 54 mice developed hepatic preneoplasia and neoplasia including foci of basophilic hepatocytes, dysplasia and carcinoma with a significantly higher incidence of lesions in females than in males. The rapid onset of liver pathologies was dependent on overexpression of the transgene since it was not detected in noninduced transgenic animals of the same age. The PML-RAR alpha protein was always present in altered tissues at much higher levels than in the surrounding normal liver tissues. In addition, overexpression of PML-RAR alpha resulted in a strong proliferative response in the hepatocytes. We conclude that overexpression of PML-RAR alpha deregulates cell proliferation and can induce tumorigenic changes in vivo.

Topics: Animals; Cell Division; Female; Gene Expression; Leukemia, Promyelocytic, Acute; Liver; Liver Neoplasms; Male; Metallothionein; Mice; Mice, Transgenic; Neoplasm Proteins; Oncogene Proteins, Fusion; Precancerous Conditions; Promoter Regions, Genetic; Zinc Sulfate

The Fas receptor appears to be commonly expressed in all morphological types of epithelial laryngeal hyperplasia (HP). Fas-mediated apoptotic cell death would thus be a possible phenomenon in these lesions. We observed more anti-apoptotic bcl-2 protein in epithelia with simple HP compared to the more advanced types of HP. It is suggested that in simple HP there is not yet a need for an early selection for cell death. The observed overexpression of metallothionein (MT) in the basal layers of simple HP would also support such a theory. These basal cells are dividing, non-apoptotic cells, which have not yet been selected for death. All 20 cysteine residues in MT are involved in metal binding, interfering with the intracellular redox balance, and thereby possibly inhibiting certain apoptotic signals. MIB-1 positivity was found only in the atypical HP, CIS, and invasive carcinomas. Intuition suggests that high labelling would be associated with poor prognosis. The degree of apoptosis, evaluated by TUNEL, did not show any differences between different types of epithelia. Although TUNEL is sensitive and rather specific, we emphasise that all TUNEL positive cells have apoptotic type morphology, confirming good and appropriate use of the technique.

Topics: Apoptosis; Carcinoma in Situ; Carcinoma, Squamous Cell; Epithelium; Fas Ligand Protein; Humans; Hyperplasia; Laryngeal Diseases; Laryngeal Mucosa; Laryngeal Neoplasms; Membrane Glycoproteins; Metallothionein; Neoplasm Invasiveness; Precancerous Conditions; Proto-Oncogene Proteins c-bcl-2

The LEC rat spontaneously develops liver cancer after suffering chronic liver injury caused by abnormal copper accumulation in the liver, but the role of copper accumulation in the induction of liver cancer remains obscure. We histochemically and biochemically examined the content of copper and metallothionein (MT), a cytoplasmic copper binding protein, in spontaneously developed preneoplastic and neoplastic liver lesions and compared them with those in the surrounding liver tissues. Histochemically, the majority of the preneoplastic liver lesions (68%) and liver cancers (59%) showed lower copper contents than the surrounding liver tissues and no lesions were shown to accumulate more copper than the surrounding tissues. A marked heterogeneity in copper staining was observed in cancer tissues. In contrast, these lesions showed an equal to higher MT content than their surroundings. Biochemical measurements of copper and MT in cancer tissues supported the histochemical findings. The bromodeoxyuridine (BrdU) labeling index was high in all cancer tissues and some of the preneoplastic liver lesions. Parts of the cancer tissues with negative or weak staining for copper were highly labeled with BrdU. Taking these results together, copper accumulation may exert a growth inhibitory effect on surrounding hepatocytes, whereas the hepatocytes in the liver lesions could proliferate, escaping from the effect of copper toxicity by increasing their MT induction and lowering copper accumulation. Thus, accumulation of copper may act as a promoting factor for the development of liver cancer in LEC rats by creating a selective growth environment.

Topics: Animals; Copper; Liver Diseases; Liver Neoplasms, Experimental; Male; Metallothionein; Precancerous Conditions; Rats; Rats, Mutant Strains; Staining and Labeling

Exposure of mice to diethylnitrosamine (DEN) in their drinking water, resulted in decreases of Cu and Zn in cytosol of both pretumorous and tumorous liver tissue. Copper was reduced 28% and zinc 44.5% in cytosol of tumorous tissue at the time of death. Analysis of Sephadex G-75 gel chromatography profiles revealed that these decreases were mainly from the high molecular weight protein pool, with smaller decreases from metallothionein. Exposure of mice to Cd in their drinking water resulted in the accumulation of most Cd on metallothionein with a smaller accumulation in the high molecular weight protein pool; Cu and Zn levels were increased in both of these cytosolic pools. When DEN was administered with Cd, there were smaller increases of Cu and Zn, and more Cd accumulated in the high molecular weight protein pool. In non-cancerous kidney of postmortem cancer patients, most Cd appeared in the high molecular weight protein pool, whereas in controls, most appeared on metallothionein.

Topics: Animals; Cadmium; Copper; Cytosol; Diethylnitrosamine; Female; Humans; Kidney; Liver Neoplasms; Male; Metallothionein; Mice; Neoplasm Proteins; Neoplasms, Experimental; Precancerous Conditions; Zinc