Induction of numerical chromosome changes and neoplastic transformation by radiations.

本文用金黄地鼠胚胎（GHE）细胞研究了X射线和紫外线照射对GHE细胞染色体畸变和肿瘤转化的诱导作用。经X射线或紫外线照射的细胞逃避衰老，并在以后的传代中表现出形态学上的转变，并伴随着在软琼脂培养基中形成集落的能力的表达。与这些变化相反，在裸鼠中观察到成瘤性的获得要晚得多（照射后11代）。当在X射线照射后的各个代次制备甲基化染色体时，根据代次数在细胞中检测到一个或两个额外的染色体。例如，在第5代显示45条染色体的细胞中，几乎所有的细胞都含有7号染色体的三体性，而转移到第13代的细胞在第6、9和/或20号染色体上有更多的染色体数目变化。在UV诱导的非贴壁依赖性细胞和致瘤细胞中观察到类似的染色体变化。用来自各种转化GHE细胞的DNA转染的小鼠NIH 3 T3细胞表达恶性表型。Southern印迹分析表明，所有转染后的NIH 3 T3恶性肿瘤细胞均含有一定量的金黄地鼠DNA，提示辐射诱导GHE细胞转化是一个多步骤的过程，特定染色体数目的改变和某些癌基因的激活可能对各转化表型的表达起重要作用。

Using gloden hamster embryo (GHE) cells, we examined the induction of chromosome changes and neoplastic transformation by X-rays or ultraviolet litht (UV).Unirradiated cells were grown at a constant growth rate for 7 passages but later ceased to divide. X-ray- or UV-irradiated cells escaped from senescence ans showed morphological transformation accompanying with the expression of the ability to form colonies in soft agar medium at later passages. In contrast to these changes, the aquisition of tumorigenicity in nude mice was observed much later (11 passages after the irradiation). When methaphese chromosomes were prepared at various passages after X-irradiation, one or two additional chromosomes were detected in the cells depending on passage numbers. For example, almost all the cells showing 45 chromosomes at passage 5 contained trisomy of chromosome 7 and the cells transferred for 13 passages had futher numerical chromosome changes on chromosome 6,9 and/or 20. Similar chromosome changes were observed in anchorage-independent and tumorigenic cells induced by UV. Mouse NIH3T3 cells transfected with DNA from various transformed GHE cells expressed malignant phenotypes. From Southern blot analysis, all malignant NIH3T3 cells derived from tumors after transfection were found to contain some amount of golden hamster DNA.These results suggest that radiation induced transformation is a multistep in GHE cells, and that the numerical change of specific chromosomes and the activation of some oncogenes may play an important role for the expression of each transformed phenotypes.