Analysis of the mechanism of chemical carcinogenesis and short-term screening of tumor-promoters using clonogenic a ssay

在用N-丁基-N-（4-羟丁基）亚硝胺（BBN）处理的大鼠中，在乳头状瘤发展之前，用膀胱细胞在软琼脂中观察到集落形成，并且形成的集落数量取决于消耗的BBN的量。结果表明，糖精钠和几种氨基酸具有促膀胱癌作用，亚致癌剂量的BBN可诱导大鼠膀胱癌细胞集落形成，提示促癌活性与集落诱导活性之间可能存在相关性，并在两阶段小鼠皮肤癌变实验中评价抗促癌剂对集落形成的影响。用维甲酸处理皮肤可抑制7，12-二甲基苯并[a]蒽（DMBA）单独作用后12-0-十四酰佛波醇-13-乙酸酯（TPA）诱导的小鼠表皮细胞软琼脂集落形成。饮食中的醋酸视黄酯的影响。去甲二氢愈创木酸（NDGA）和盐酸奎纳克林对大鼠膀胱细胞软琼脂集落形成的影响。用亚致癌剂量的BBN处理后，糖精钠诱导的膀胱细胞软琼脂集落形成被给予醋酸视黄酯或NDGA抑制。因此，将克隆形成实验应用于肿瘤发生实验中，可用于分析肿瘤发生的早期事件，并为发现新的肿瘤促进剂和抗肿瘤促进剂提供一种短期的筛选方法。

Colony formation in soft agar was observed with bladder cells prior to papilloma development in rats treated with N- Butyl-N-(4-hydroxybutyl)nitrosamine(BBN), and the number of colonies formed was dependent on the quantity of BBN consumed. It was then demonstrated that sodium saccharin and several amino acids, which are known to act as rat bladder cancer promoters, induce colony formation of rat bladder cells after treatment with subcarcinogenic dose of BBN, suggesting that there may be a correlation between tumor-promoting activity and colony inducing activity.Effect of anti-tumor-promoter on colony formation was then assessed in two-stage mouse skin carcinogenesis experiment. Soft agar colony formation of mouse epidermal cells induced by 12-0- tetradecanoylphorbol-13-acetate(TPA) after single application of 7,12-dimethylbenz[a]anthracene(DMBA) was inhibited by treatment of skin with retinoic acid. Effect of dietary retinyl acetate. nordihydroguaiaretic acid(NDGA) and quinacrine hydrochloride on soft agar colony formation of rat bladder cells was also eaaluated. Soft agar colony formation of bladder cells induced by sodium saccharin after treatment with subcarcinogenic dose of BBN was inhibited by the administration of retinyl acetate or NDGA. suggesting the possible anti-tumor-promoting activity of the two agents.Thus, an application of clonogenic assay to carcinogenesis experiment could be useful to analyse early events in carcinogenesis and provide a short-term screening method for detecting new tumor-promoters and anti-tumor-promoters.