thioguanine-anhydrous and Liver-Neoplasms

Infliximab-induced hepatotoxicity is reported in several case studies involving patients with inflammatory bowel disease (IBD) and a direct hepatotoxic effect has been proposed.. The aim of this study was to determine the direct in vitro toxicity of infliximab. As a proof of principle the in vitro toxicity of thiopurines and methotrexate was also determined.. Cell survival curves and the half maximal inhibitory concentrations (IC(50)) were obtained after 24, 48 and 72 h of incubation in HepG2 cells with the IBD drugs azathioprine, 6-mercaptopurine, 6-thioguanine, methotrexate or infliximab by using the WST-1 cytotoxicity assay.. No in vitro hepatotoxicity in HepG2 cells was seen with infliximab, while concentration-dependent cytotoxicity was observed when HepG2 cells were incubated with increasing concentrations of azathioprine, 6-mercaptopurine and 6-thioguanine.. Infliximab alone or given in combination with azathioprine showed no direct hepatotoxic effect in vitro, indicating that the postulated direct hepatotoxicity of infliximab is unlikely.

Topics: Analysis of Variance; Antibodies, Monoclonal; Azathioprine; Cell Survival; Dose-Response Relationship, Drug; Hep G2 Cells; Hepatoblastoma; Humans; In Vitro Techniques; Inflammatory Bowel Diseases; Infliximab; Liver Neoplasms; Mercaptopurine; Methotrexate; Sensitivity and Specificity; Thioguanine

Human hepatoma cells deficient in HPRT activity were isolated by challenging HepG2 cells with 6-thioguanine (6TG). Three 6TG-resistant isolates were plated in selective media, and each clonal line displayed an 8-azaguanine-resistant, HAT-sensitive phenotype. The HPRT-deficient phenotype of one of these clones, H30-1, was confirmed in genetic tests: the HAT-sensitivity of H30-1 cells was complemented by fusion by HPRT+ (Ltk-) but not HPRT- (A9) cells. Furthermore, transfection of the bacterial xanthine-guanine phosphoribosyl transferase (gpt) gene into H30-1 cells rendered them HAT-resistant. H30-1 cells maintained the differentiated morphology, growth characteristics, fusion properties, and transfection efficiencies typical of parental HepG2 cells, and they expressed several liver-specific genes. Finally, the H30-1 cell line contained a modal number of 50 chromosomes. Therefore, H30-1 cells represent an HPRT-deficient HepG2 derivative that retains its differentiated phenotype in vitro.

Topics: Carcinoma, Hepatocellular; Cell Fusion; Gene Expression; Genetic Complementation Test; Humans; Hybrid Cells; Hypoxanthine Phosphoribosyltransferase; Karyotyping; Liver Neoplasms; Phenotype; Thioguanine; Transfection; Tumor Cells, Cultured

Genetic toxicology assays that rely on S9 microsomal mixes are subject to artifacts related to the generation of mutagenic metabolites by acidic pHs, variation in individual isolations of microsomes and the failure of subcellular fractions to faithfully produce metabolites generated in intact cells. We have developed a gene mutation assay utilizing the human hepatoma cell line HepG2, which has been shown to metabolize a broad spectrum of promutagens. Optimal conditions for assaying the induction of 6-thioguanine-resistant mutants in this cell line include: 1) growth of colonies for three weeks on lethally irradiated feeder layers of 10(6) thioguanine-resistant HepG2 cells (average plating efficiency = 60-80%); 2) a thioguanine concentration in selection dishes of 10(-4) M with a maximum seeding density of 2.5 x 10(5) cells per 100 mm culture dish; and 3) a minimum expression time of 6 days. In addition to ultraviolet light C (254 nm), a cytochrome P450 (cyclophosphamide)-dependent and a cytochrome P448 (aflatoxin B1)-dependent promutagen were shown to induce cytotoxicity and mutations in this test system. The present studies, therefore, suggest that the HepG2 cell line may be useful for a variety of assays in genetic toxicology.

Topics: Aflatoxins; Biotransformation; Carcinoma, Hepatocellular; Cell Line; Cyclophosphamide; Drug Resistance; Evaluation Studies as Topic; Humans; Liver Neoplasms; Mutagenicity Tests; Thioguanine; Ultraviolet Rays

Cholestatic jaundice induced by hepatic intra-arterial 5-fluorodeoxyuridine (FUDR) demonstrated marked improvement in three patients following treatment with oral corticosteroids. Subsequent "prophylactic" use allowed continuation of chemotherapy and improved quality of life. Corticosteroid use in selected patients with FUDR-induced cholestatic jaundice may be beneficial.

Topics: Adrenal Cortex Hormones; Cholestasis; Colonic Neoplasms; Floxuridine; Humans; Infusions, Intra-Arterial; Liver Neoplasms; Male; Rectal Neoplasms; Thioguanine

A dose dependent inhibition of intercellular communication (metabolic cooperation) between primary cultures of rat liver hepatocytes and an established adult rat liver epithelial cell 6-thioguanine resistant strain by the liver tumor promoter 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) is demonstrated. This in vitro assay is proposed to evaluate the tumor promoting activity of oncogenic agents shown to be non-genotoxic in the liver culture systems.

Topics: Animals; Cell Communication; Cells, Cultured; DDT; Dose-Response Relationship, Drug; Liver; Liver Neoplasms; Rats; Thioguanine

Topics: Carcinogens; Cells, Cultured; DNA Repair; Hypoxanthine Phosphoribosyltransferase; Liver; Liver Neoplasms; Mutagenicity Tests; Mutagens; Mutation; Thioguanine

Topics: Alkylating Agents; Animals; Antineoplastic Agents; Azaguanine; Azaserine; Carcinoma, Ehrlich Tumor; Carcinoma, Hepatocellular; DNA; DNA, Neoplasm; Fluorouracil; Idoxuridine; Liver Neoplasms; Lymphoma; Lymphoma, Non-Hodgkin; Mercaptopurine; Mice; Neoplasms, Experimental; Nitrogen Mustard Compounds; Nucleosides; Nucleotides; Purines; Research; RNA; RNA, Neoplasm; Sarcoma 180; Thioguanine; Uracil Mustard