DNA DAMAGE BY ALKYLATING AGENTS AND THEIR REPAIR IN HUMAN TUMOR CELLS

R. S. Day，III，D. Yarosh和其他人已经表明， 大约20%的人肿瘤细胞系和病毒转化的 线是过敏的烷化剂，由于明显的 不存在烷基鸟嘌呤烷基转移酶。 我们已经能够 从人肝中部分纯化酶。 这种酶 去除鸟嘌呤06位的烷基化损伤， DNA中的其他位点。 我们计划进一步描述 酶，并将其纯化到氨基酸序列 信息获取。 与D合作。Yarosh，人类 肝脏提取物被用来分离足够数量的 这种蛋白质。 特定RNA转录的差异 在mer+和mer-细胞系中进行了研究。 与 杂交消减，构建cDNA文库， mer+细胞，其已经耗尽了与 匹配的mer细胞系。 然而，当其它mer+和mer- 线，这种相关性是不一致的-即，没有一 从转录本编码的cDNA克隆一致地更 与mer-细胞系相比，mer+丰富。

R. S. Day, III, D. Yarosh, and others have shown that approximately 20% of human tumor lines and viral transformed lines are hypersensitive to alkylating agents due to an apparent absence of Alkylguanine Alkytransferase. We have been able to partially purify the enzyme from human liver. This enzyme removes alkylation damage at the 06 position of guanine but not at other sites in DNA. We plan to further characterize this enzyme and purify it to the point where amino acid sequence information in obtained. In collaboration with D. Yarosh, human liver extracts are being used to isolate adequate quantities of this protein. Differences in the transcription of specific RNAs in mer+ and mer- cell lines were investigated. With hybridization subtraction, a cDNA library was constructed from a mer+ cell which has been depleted of sequences common to matched mer-cell lines. However, when other mer+ and mer- lines were used, this correlation was not consistent - i.e., none of the cDNA clones coded from a transcript consistently more abundant in mer+ compared to mer- cell lines.