QUANTITATIVE STUDIES ON CONCURRENT FACTORS IN NEOPLASTIC TRANSFORMATION

用以下方法研究BALB/3 T3克隆A41-1-1细胞系 试验：细胞毒性、哇巴因抗性（oua-r）突变、形态学 肿瘤转化，DNA损伤和修复，如碱性磷酸酶测定的 洗脱和除去烷基化DNA加合物，如通过HPLC测量的。 的 确定了这些生物学终点的相对反应水平 在用烷基化剂处理后，N-甲基-N '-硝基-N- 亚硝基胍（MNNG）和N-乙基亚硝基脲（ENU）。 一些分离 去年报告的现象得到证实，并进一步调查了这一点。 年 暴露于含有给定初始浓度的介质的持续时间 ENU浓度决定了最大反应， 不同的终点。 短暴露持续时间（5分钟） 足以诱导最大水平的oua-r突变和DNA单 链断裂（SSB），而转化的最大诱导， 细胞毒作用时间为45-60 min。 其他研究 用ENU对中国人进行了暴露时间依赖性反应 仓鼠卵巢（CHO）细胞，其中oua-r突变和6-硫鸟嘌呤 可以测定耐药性（6-TG-r）突变。 的诱导动力学 CHO细胞中的oua-r突变和ssb显示早期最大诱导 类似于在BALB/3 T3细胞中观察到的，而6-TG-r突变 随着时间的推移，诱导率逐渐升高，这与 理论曲线的基础上的线性关系的expotential衰减 中的ENU。 BALB/3 T3细胞快速去除06-乙基鸟嘌呤， N3-乙胺的程度较低，而在60分钟内没有去除， 检测N7-乙基鸟嘌呤、04-乙基胸腺嘧啶和乙基磷酸三酯。 然而，CHO细胞不能修复06-乙基鸟嘌呤， 病变 因此，06-烷基鸟嘌呤的修复不太可能解释细胞的凋亡。 Oua-R突变和SSB的早期最大反应。 时间 解离模型正在进一步研究，以阐明 转化的诱导时间长。

The BALB/3T3 clone A41-1-1 cell line was studied with the following assays: cytotoxicity, ouabain resistance (oua-r) mutations, morphological neoplastic transformation, DNA damage and repair as measured by alkaline elution and removal of alkylated DNA adducts as measured by HPLC. The relative levels of response for these biological end points were determined after treatment with the alkylating agents, N-methyl-N'-nitro-N- nitrosoguanidine (MNNG) and N-ethlnitrosourea (ENU). A few dissociation phenomenon, reported last year, was confirmed and further investigated this year. Duration of the exposure to a medium containing a given initial concentration of ENU determined maximal responses that differed remarkably for different end-points. Short exposure duration times (5 min) were sufficient to induce maximal levels of oua-r mutations and of DNA single strand breaks (ssb), whereas the maximal induction of transformation as well as of cytotoxicity required 45-60 mins. Additional studies of exposure time-dependent responses were conducted with ENU in Chinese hamster ovary (CHO) cells, for which both oua-r mutations and 6-thioguanine resistance (6-TG-r) mutations can be assayed. The induction kenetics of oua-r mutations and ssb in CHO cells showed early maximal induction analogous to that observed in the BALB/3T3 cells, whereas 6-TG-r mutations were induced at progressively higher rates in time, consistent with a theoretical curve based on a linear relationship to expotential decay of ENU in the medium. BALB/3T3 cells removed 06-ethylguanine rapidly and N3-ethyladeine to a lesser degree, whereas no removal within 60 min was detected for N7-ethylguanine, 04-ethylthymine and ethyl-phosphotriesters. The CHO cells, however, were not capable of repairing 06-ethylguanine lesions. Repair of 06-alkylguanine, therefore, is unlikely to explain the early maximal response of oua-r mutations and ssb. The temporal dissociation model is being further studied to clarify the basis for the long induction times for transformation.