Alternative to breast carcinogenicity test using a tissue culture method

我们建立了一种新的体外微核试验，利用培养的小鼠乳腺上皮细胞作为组织特异性筛查可疑乳腺癌的方法。孕鼠乳腺上皮细胞在添加胰岛素、表皮生长因子、转铁蛋白、霍乱毒素、牛血清白蛋白和抗生素的无血清Ham‘s F-12/Dulbecco’s改良Eagle‘s培养液中培养。在本研究中，N-甲基-N-亚硝脲、N-丁基-N-亚硝脲、7，12-二甲基苯并(A)菲、20-甲基胆蒽、2-乙酰氨基荧烯、N-甲基-N‘-亚硝基-亚硝胺等5种乳腺癌致癌物和直接致癌物N-甲基-N’-硝基-亚硝胺均能引起小鼠乳腺上皮细胞微核的增加，并呈剂量依赖关系。这些结果证明了使用微核作为一种短期的、体外筛选可疑的乳腺癌致癌物的方法是合理的。

We developed a new in vitro micronucleus test using cultured mouse mammary epithelial cells as a tissue-specific screen for suspected breast carcinogens.Mammary epithelial cells from pregnant mice were cultured in serumfree Ham's F-12/Dulbecco's modified Eagle's medium supplemented with insulin, epidermal growth factor, transferin, cholera toxin, bovine serum albumin and antibiotics. Several breast carcinogens and other chemicals were added to the culturds at day 6 of culture, and the number of micronuclei per 1, 000 cells was scored at 24hr after treatment.In the present study, five breast carcinogens, N-methyl-N-nitrosourea, N-butyl-N-nitrosourea, 7, 12-mdimethylbenz (a) anthracene, 20-methylcholanthrene and 2-acetamidofluorene, and one direct carcinogen, N-methyl-N'-nitro-Nnitrosoguanidine increased the micronuclei incidence in the cultures.Since all breast carcinogens and a direct carcinogen induced micronuclei in the culture of mouse mammary epitherial cells in a dose related manner, but other agents generally do not, these results justify the use of micronuclei as a short term, in vitro screen of suspected breast carcinogens.