Varshavsky A, Barsoum J, Roninson I, Snapka R
Princess Takamatsu Symp. 1983;14:235-54.
We discuss our recent findings in three related areas of the gene amplification field. 1) We have found that tumor-promoting phorbol esters, nonphorbol tumor promoters, and most significantly, mitogenic hormones, such as insulin, vasopressin, and epidermal growth factor (EGF), greatly increase the incidence of methotrexate (MTX) resistance in 3T6 cells under condition of MTX selection. Most of these MTX-resistant cells bear amplified dihydrofolate reductase (DHFR) genes. 2) We have discovered that when mouse cells bearing unstably amplified DHFR genes are grown in the presence of nonlethal concentrations of hydroxyurea (HU), the rate of loss of the DHFR genes from these cells is greatly increased. 3) We have developed a new method for detection and mapping of homologous, repeated and amplified DNA sequences, and have used this method to detect and clone amplified DNA fragments in mammalian cells resistant simultaneously to a number of different drugs.
我们讨论了基因扩增领域三个相关领域的近期研究发现。1）我们发现，促肿瘤佛波酯、非佛波肿瘤启动子，以及最显著的是有丝分裂激素，如胰岛素、血管加压素和表皮生长因子（EGF），在甲氨蝶呤（MTX）选择条件下，能大幅增加3T6细胞中甲氨蝶呤耐药性的发生率。这些MTX耐药细胞大多带有扩增的二氢叶酸还原酶（DHFR）基因。2）我们发现，当携带不稳定扩增的DHFR基因的小鼠细胞在非致死浓度的羟基脲（HU）存在下生长时，这些细胞中DHFR基因的丢失率会大大增加。3）我们开发了一种检测和定位同源、重复和扩增DNA序列的新方法，并已使用该方法在对多种不同药物同时耐药的哺乳动物细胞中检测和克隆扩增的DNA片段。
