Application of the improved BALB/c 3T3 cell transformation assay to the examination of the initiating and promoting activities of chemicals: The second interlaboratory collaborative study by the non-genotoxic carcinogen study group of Japan
Tsuchiya T.,Banyu Pharmaceutical Co. |
Umeda M.,Hatano Research Institute |
Tanaka N.,Hatano Research Institute |
Sakai A.,Hatano Research Institute |
And 37 more authors.
ATLA Alternatives to Laboratory Animals | Year: 2010
The Non-genotoxic Carcinogen Study Group in the Environmental Mutagen Society of Japan organised the second step of the inter-laboratory collaborative study on one-stage and two-stage cell transformation assays employing BALB/c 3T3 cells, with the objective of confirming whether the respective laboratories could independently produce results relevant to initiation or promotion. The method was modified to use a medium consisting of DMEM/F12 supplemented with 2% fetal bovine serum and a mixture of insulin, transferrin, ethanolamine and sodium selenite, at the stationary phase of cell growth. Seventeen laboratories collaborated in this study, and each chemical was tested by three to five laboratories. Comparison between the one-stage and two-stage assays revealed that the latter method would be beneficial in the screening of chemicals. In the test for initiating activity with the two-stage assay (post-treated with 0.1μg/ml 12-O-tetradecanoylphorbol-13-acetate), the relevant test laboratories all obtained positive results for benzo[a]pyrene and methylmethane sulphonate, and negative results for phenanthrene. Of those laboratories assigned phenacetin for the initiation phase, two returned positive results and two returned negative results, where the latter laboratories tested up to one dose lower than the maximum dose used by the former laboratories. In the exploration of promoting activity with the two-stage assay (pretreated with 0.2μg/ml 3-methylcholanthrene), the relevant test laboratories obtained positive results for mezerein, sodium orthovanadate and TGF-β1, and negative results for anthralin, phenacetin and phorbol. Two results returned for phorbol 12, 13-didecanoate were positive, but one result was negative - again, the maximum dose to achieve the latter result was lower than that which produced the former results. These results suggest that this modified assay method is relevant, reproducible and transferable, provided that dosing issues, such as the determination of the maximum dose, are adequately considered. The application of this two-stage assay for screening the initiating and promoting potential of chemicals is recommended for consideration by other research groups and regulatory authorities.
Umano T.,Chemicals Evaluation and Research Institute |
Tanaka R.,Biosafety Research Center Foods |
Yamasaki K.,Chemicals Evaluation and Research Institute
Archives of Toxicology | Year: 2012
The purpose of this study was to investigate the endocrine-mediated effects of 4,4'-(hexafluoroisopropylidene)diphenol according to OECD test guideline no. 407. The estrogenic properties of this chemical have already been shown on uterotrophic assay, and this chemical is classified as a low-production volume chemical in REACH program. Rats were orally gavaged with 0, 10, 30, and 100 mg/kg/day of test chemical for at least 28 days, beginning at 8 weeks of age. In the 100 mg/kg group of male rats, endocrine-mediated effects, atrophic changes in the mammary glands and testicular Leydig cells, decreased accessory sex organ weights, and hypertrophy of the adrenal zona fasciculata with increased organ weights were seen; there was dysfunction of the estrous cycle in the 30 and 100 mg/kg groups, and increased serum T4 values were observed in the 100 mg/kg groups of both sexes. In addition, we also noted other findings, such as reduced body weight gains in the 30 and/or 100 mg/kg groups of both sexes, dilatation of the large intestinal lumen in the 100 mg/kg groups of both sexes, decreased hematopoiesis in the bone marrow and spleen, and decreased white blood cell counts in the 100 mg/kg group of male rats. Our results demonstrate that in a repeated-dose toxicity study, 4,4'-(hexafluoroisopropylidene)diphenol has various endocrine-mediated effects and its NOAEL (no observed adverse effect level) is 10 mg/kg/day. © 2011 Springer-Verlag.