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7,12-Dimethylbenz[a]anthracene
About: 7,12-Dimethylbenz[a]anthracene is a research topic. Over the lifetime, 1717 publications have been published within this topic receiving 40892 citations.
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TL;DR: Results indicate that the regimen of biweekly DMBA applications commits HBPE to neoplastic development within three weeks and that subsequent cellular or molecular changes occurring during greater than or equal to 2 succeeding weeks of DMBA treatment are necessary to manifest the transformation associated phenotypes of continuous passageability, anchorage-independent growth, and induction of NIH3T3 transformants following DNA transfection.
Abstract: Experiments were performed to determine the rate at which hamster buccal pouch epithelium (HBPE) is committed to neoplastic development during a regimen of biweekly topical applications of 7,12-dimethylbenz[a]anthracene (DMBA) in mineral oil, administered for 1, 2, 3, 5 or 10 weeks. Evaluated indices of neoplastic commitment were: (i) primary tumor formation, (ii) passageability of HBPE cells in surface culture, (iii) anchorage-independent growth in soft agar and (iv) induction of the transformed phenotype in NIH3T3 cells following transfection with HBPE DNA. Groups of 12-15 hamsters, exposed to DMBA for 1, 2 and 3 weeks, developed buccal pouch tumor incidences of 13%, 42% and 71% respectively within 44 weeks. Buccal pouches of ten control hamsters treated for three weeks with mineral oil did not develop buccal pouch neoplasms during an observation period of 44 weeks. Whereas cultured HBPE cells obtained following three weeks of in vivo DMBA exposure were negative in assays for anchorage-independent growth, passageability in surface culture and induction of NIH3T3 transformants following DNA transfection, similarly cultured cells obtained following five and ten weeks of in vivo exposure were positive, or marginally positive, in each of these assays. These results indicate that (i) the regimen of biweekly DMBA applications commits HBPE to neoplastic development within three weeks and that (ii) subsequent cellular or molecular changes occurring during greater than or equal to 2 succeeding weeks of DMBA treatment are necessary to manifest the transformation associated phenotypes of continuous passageability, anchorage-independent growth, and induction of NIH3T3 transformants following DNA transfection.
12 citations
TL;DR: Oral administration of ferulic acid at a dose of 40 mg/kg body weight to hamsters treated with DMBA completely prevented the tumor formation and downregulated the expression of COX-2, NF-B and VEGF during DMBA induced oral carcinogenesis.
Abstract: Ferulic acid, a natural antioxidant, has the potential to prevent inflammation and to modulate angiogenesis in both in vivo and in vitro models. The present study has investigated the modulating effect of ferulic acid on the expression pattern of COX-2, NF-B and VEGF during 7,12-dimethylbenz(a)anthracene (DMBA) induced hamster buccal pouch carcinogenesis. Over expression of COX-2, NF-B and VEGF was noticed in the oral tumor tissues of hamsters treated with DMBA. Oral administration of ferulic acid at a dose of 40 mg/kg body weight to hamsters treated with DMBA completely prevented the tumor formation and downregulated the expression of COX-2, NF-B and VEGF during DMBA induced oral carcinogenesis. The present results suggest that ferulic acid might have suppressed oral tumor formation by down regulating the expression of COX-2, NF-B and VEGF during DMBA induced oral carcinogenesis.
12 citations
TL;DR: The experiments examine how retinol and retinoic acid can decrease the frequency of sister chromatid exchange induced by two indirect mutagens/carcinogens in an epithelial liver cell line of male Chinese hamster (CHEL cells).
Abstract: Recently, retinoids have been studied for their ability to modify the carcinogenic/mutagenic activity of chemical compounds. Results show that they can inhibit the malignant transformation of cells, the induction of cancer in experimental animals and the mutagenicity of promutagens. Our experiments examine how retinol and retinoic acid can decrease the frequency of sister chromatid exchange (SCE) induced by two indirect mutagens/carcinogens (cyclophosphamide and 7,12-dimethylbenz[a]anthracene) in an epithelial liver cell line of male Chinese hamster (CHEL cells). These cells are metabolically competent and activate different classes of promutagens into biologically active metabolites. Our results are consistent with the suggestion that retinoids modulate the genotoxicity of indirect-acting mutagens by altering their metabolic activation or cellular detoxification processes or both.
12 citations
TL;DR: The present experiment was undertaken to investigate the effect of DMBA in Lewis rats, when administered subcutaneously at birth at different dose levels.
Abstract: AVARIETY of strains of mice respond to the administration of chemical carcinogens at birth with the development of a bigh incidence of malignant lymphomas and of certain other tumours (Pietra, Spencer and Shubik, 1959; Pietra, Rappaport and Shubik, 1961; K'elly and O'Gara, 1961 ; Fiore-Donati et al., 1961; Roe, Rowson and Salaman, 1961; Toth, Rappaport and Shubik, 1962 ; Doell and Carnes, 1962). The carcinogen 7,12-dimethylbenz(a)anthracene (DMBA) was found to be a very potent leukaemogenic agent for mice when injected subcutaneously at birth (Pietra, Spencer and Shubik, 1959; Pietra, Rappaport and Shubik, 1961 ; Roe, Rowson and Salaman, 1961 ; Toth, Rappaport and Shubik, 1962). Its effects at different dose levels and on mice of different age have been studied (Toth, Rappaport and Shubik, 1963). In adult rats of various strains subcutaneous administration of DMBA was found to induce mainly sarcomas at the site of injection (Davenport et al., 1941 ; Berenblum, 1949) while administration of this carcinogen by other routes resulted mainly in the development of mammary tumours (Geyer et al., 1951 ; Howell, 1960 ; Huggins, Grand and BriHantes, 1961 ; Boyland and Sydnor, 1962). The present experiment was undertaken to investigate the effect of DMBA in Lewis rats, when administered subcutaneously at birth at different dose levels.
12 citations
Journal Article•
TL;DR: Female rats were treated with buformin, phenytoin, polypeptide pineal extract, L-DOPA or bu formin combined with L- DOPA during 3 weeks before intravenous injections of DMBA over a period of carcinogen injections and after it till the animals' death.
Abstract: Female rats were treated with buformin, phenytoin, polypeptide pineal extract, L-DOPA or buformin combined with L-DOPA during 3 weeks before intravenous injections of DMBA (1.5 mg 6 times with one-week intervals) over a period of carcinogen injections and after it till the animals' death. The overall tumour incidence in the control group was 97%, while in buformin, phenytoin, pineal extract, L-DOPA and buformin + L-DOPA treated groups it amounted to 55, 71, 80, 50 and 62%, respectively (P < 0.05). The incidence of mammary adenocarcinoma amounted to 81, 36, 55, 26, 25 and 19%, respectively (P < 0.05). The mechanisms of the similar effects the drugs belonging to different classes produce on chemical carcinogenesis are discussed.
12 citations