BUDR DEPENDENCE, MALIGNANCY, AND DIFFERENTIATION

长期目标是阐明参与的分子机制， 调节恶性转化、分化和染色体 哺乳动物细胞中的重组。 这些领域是一个 了解癌症、正常发育和出生缺陷， 与染色体断裂综合征有关的疾病。 基本 这些技术是哺乳动物细胞遗传学和重组DNA技术。 的 具体目标是：（1）确定胸腺素的机制， (dT)类似物5-溴脱氧尿苷（BrdU）抑制叙利亚分化 仓鼠黑色素瘤细胞，以及脱氧胞苷如何逆转抑制 分化而不影响DNA中BrdU的量;这些研究 将涉及代谢示踪实验和克隆多巴氧化酶 基因作为分子探针;（2）进行能力的遗传分析 突变细胞的生存与DNA中的所有dT残基被替换， BrdU，克隆与该表型相关的基因;（3）分析与该表型相关的 BrdU诱导姐妹染色单体交换（SCE）的机制，以及 确定是否能够检测 链间重组可用于研究SCE的诱导;（4） 分析表现出BrdU依赖性并表达 转化的表型仅在BrdU存在下，并确定是否 BrdU依赖是由于BrdU激活的癌基因;（5）建立一个新的 利用杂合胶原启动子质粒的癌基因检测系统 其在癌基因转化细胞中的表达被抑制;和（6） 检查杂交种中恶性转化的表达， 转化的和未转化的细胞，利用胶原启动子 质粒，并确定特定的人类染色体是否携带 抑制杂交细胞转化的基因。

The long term goals are to elucidate the molecular mechanisms involved in regulating malignant transformation, differentiation, and chromosomal recombination in mammalian cells. These areas are central to an understanding of cancer, of normal development and birth defects, and of diseases associated with chromosomal breakage syndromes. The basic techniques are those of mammalian cell genetics and recombinant DNA. The specific aims are to: (1) determine the mechanism by which the thymdine (dT) analog 5-bromodeoxyuridine (BrdU) suppresses differentiation in Syrian hamster melanoma cells, and how deoxycytidine reverses the suppression of differentiation without affecting the amount of BrdU in DNA; these studies will involve matabolic tracer experiments and also a cloned dopa oxidase gene as a molecular probe; (2) carry out a genetic analysis of the ability of mutant cells to survive with all the dT residues in DNA replaced by BrdU, and clone the gene responsible for this phenotype; (3) analyze the mechanism by which BrdU induces sister chromatid exchanges (SCE), and determine whether a plasmid recombination system capable of detecting interstrand recombination can be used to study the induction of SCE; (4) analyze mutant melanoma cells which exhibit BrdU dependence and express the transformed phenotype only in the presence of BrdU, and determine whether BrdU dependence is due to a BrdU-activated oncogene; (5) establish a new system for oncogene detection, utilizing hybrid collagen promoter plasmids whose expression is suppressed in oncogene transformed cells; and (6) examine the expression of malignant transformation in hybrids between transformed and untransformed cells, utilizing the collagen promoter plasmids mentioned above, and determine if specific human chromosomes carry genes that suppress transformation in hybrid cells.