MUTATION AND DEREPRESSION OF GENES IN CARCINOGENESIS

这一提议的基本工作假设是癌症的发生 是一个多阶段的过程，由不可逆的 正常细胞到癌前细胞(即起始期)和克隆性 将被启动的细胞放大到“临界质量”，允许 转移表型出现(即，促进和进展阶段)。 我们对这两个截然不同但又相互依存的过程的目标 在癌变过程中继续对生物化学和 用体外技术研究启动和促进的细胞机制 与包括人类在内的各种哺乳动物的细胞。具体来说，我们将 研究：a)哺乳动物的诱变及其在启动过程中的可能作用 癌变阶段和b)缝隙连接细胞间通讯 以及它在促进肿瘤方面的潜在作用。 我们将使用我们的中国仓鼠V79阿尔法DNA聚合酶“突变体” (抗蚜虫素)突变体研究其在自发和诱导中的作用 突变通过表征各种类型的回复突变体，其中一些具有 α-DNA中假定的质或量的变化 聚合酶，以及其他核苷酸池发生变化的基因。我们还将尝试 分离对蜂王素敏感的中国仓鼠细胞以检测是否确定 突变的Alpha DNA聚合酶可能是“抗突变因子”。此外，我们 将扩大我们对阿尔法DNA聚合酶在基因和 染色体扩增。 将研究缝隙连接通讯在肿瘤促进中的作用。 通过扩大我们的观察范围，某些癌基因(即src、ras) 抑制细胞间通讯。含有src和ras基因的质粒 基因将分别转入缝隙连接熟练者体内。 中国仓鼠细胞，并成为一种沟通和 二乙基己烯甾醇诱导大鼠肝脏“卵圆”细胞系。 此外，我们还将研究ras和myc癌基因的可能作用， 单独和组合在一起，关于细胞通信和转化。 我们将使用传统的技术来测量缝隙连接 函数，我们最新开发的两项技术，“荧光 光漂白后的再分配“(FRAP分析)和”刮载“ 对缝隙连接功能进行研究。

The fundamental working hypothesis of this proposal is that carcinogenesis is a multi-staged process, consisting of an irreversible conversion of the normal cell to a premalignant cell (i.e., initiation phase) and the clonal amplification of the initiated cell to a "critical mass" allowing the metastatic phenotype to appear (i.e., promotion and progression phases). Our aim on these two distinctly different but interdependent processes during carcinogenesis continues to be the study of the biochemical and cellular mechanisms of initiation and promotion using in vitro techniques with various mammalial, including human, cells. Specifically, we will study: a) mammalian mutagenesis and its possible role in the initiation phase of carcinogenesis and b) gap-junctional intercellular communication and its potential role in tumor promotion. We will use our Chinese hamster V79 Alpha DNA polymerase "mutator" (aphidicolin-resistant) mutant to study its role in spontaneous and induced mutations by characterizing various types of revertant mutants, some with presumptive qualitative or quantitative changes in the Alpha-DNA polymerase, and others with altered nucleotide pools. We will also attempt to isolate aphidicolin-sensitive Chinese hamster cells to test if certain mutant Alpha DNA polymerases could be "anti-mutators". In addition, we will extend our studies on the role of Alpha DNA polymerase on gene and chromosomal amplification. The role of gap-junctional communication in tumor promotion will be studied by extending our observations that certain oncogenes (i.e., src, ras) inhibit intercellular communication. Plasmids containing the src and ras genes, respectively, will be transfected into the gap-junction proficient Chinese hamster cells, and into a communicating and diethylstibesterol-differentiation-inducible rat liver "oval" cell line. In addition, we will study the possible role of ras and myc oncogenes, alone and in combination, on cell communication and transformation. We will be using, along with traditional techniques to measure gap-junction function, two of our newly developed techniques, "Fluorescence Redistribution After Photobleaching" (FRAP analysis) and "scrape-loading" to perform our studies on gap-junction function.