Carcinogen-mediated co-activation of two independent genes in Chinese hamster cells.
Carcinogen-mediated co-activation of two independent genes in Chinese hamster cells.
复制标题
致癌物介导的中国仓鼠细胞中两个独立基因的共激活。
作者：
T. Kleinberger;E. Sahar;S. Lavi
致癌物处理后，通过用荧光甲氨蝶呤标记细胞来测量二氢叶酸还原酶（dhfr）表达水平的升高，该荧光甲氨蝶呤与该酶结合。将致癌物处理的、猿猴病毒40（SV 40）转化的中国仓鼠胚胎细胞（C 060）分成dhfr表达水平不同的亚群，发现在相同细胞中dhfr和SV 40 T抗原的共表达水平增强。dhfr的表达增加是扩增无关的，而T抗原编码序列被扩增。在用pSV 2CAT-SVgpt（CC 24）稳定转化的CHO细胞中测量dhfr和与早期SV 40调节区连接的细菌氯霉素乙酰转移酶基因的共表达。这两个序列在处理的细胞中以更高的水平表达，并且在相同的细胞亚群中观察到升高的表达水平，尽管没有检测到它们的基因拷贝数增加。在相同细胞中两个独立基因的增强表达的伴随激活表明，在致癌剂处理的细胞中，控制基因表达的细胞因子被激活。这些研究结果的影响，细胞控制机制和致癌过程进行了讨论。
Following carcinogen treatment, elevated expression levels of dihydrofolate reductase (dhfr) were measured by labeling cells with fluorescent methotrexate which binds to this enzyme. Fractionation of carcinogen-treated, Simian virus 40 (SV40)-transformed Chinese hamster embryo cells (C060) into subpopulations differing in their levels of dhfr expression revealed co-expression, at enhanced levels, of dhfr and SV40 T antigen in the same cells. The increased expression of dhfr was amplification independent, while the T antigen coding sequences were amplified. The co-expression of dhfr and the bacterial chloramphenicol acetyltransferase gene linked to the early SV40 regulatory region was measured in CHO cells stably transformed by pSV2CAT-SVgpt (CC24). Both these sequences were expressed at higher levels in treated cells and the elevated expression levels were observed in the same subpopulation of cells, although no increase in their gene copy number was detected. The concomitant activation of enhanced expression of two independent genes in the same cells suggests that cellular factors governing gene expression are activated in the carcinogen-treated cells. The implications of these findings to cellular control mechanisms and to the carcinogenic process are discussed.