Kennedy A R, Little J B
Radiat Res. 1984 Aug;99(2):228-48.
It has previously been hypothesized that radiation transformation in vitro is a two-step process; the first step is a frequent alteration occurring among a large fraction of the irradiated cells, while the second step, malignant transformation, is a rare event occurring with an approximate frequency of 10(-6) among the progeny of the irradiated cells. Data are reported here on the distributions of transformed-cell clone sizes in irradiated cultures reseeded at various times post-treatment. The results suggest that the second event in transformation occurs randomly during the growth of irradiated cultures of C3H 10T1/2 cells to confluence. When the same number of irradiated C3H 10T1/2 cells were seeded into petri dishes of different sizes [35 mm (8 cm2), 60 mm (21 cm2), 100 mm (55 cm2), 150 mm (145 cm2)], the number of foci which arose per dish was dependent on the final cell numbers at confluence in the various dish sizes, such that the number of foci/cm2 was constant. When irradiated cells and parental C3H 10T1/2 cells were mixed in different proportions at low density, the number of foci which ultimately arose was a function of the number of progeny of irradiated cells present in the culture at confluence. The results presented here confirm previous studies and give further evidence that the radiation-induced malignant transformation of cells occurs in an indirect, multistage fashion.
先前曾有人提出假说，体外辐射转化是一个两步过程；第一步是在大部分受辐照细胞中频繁发生的改变，而第二步，即恶性转化，是在受辐照细胞后代中以约10(-6)的频率发生的罕见事件。本文报道了在处理后不同时间重新接种的受辐照培养物中转化细胞克隆大小的分布数据。结果表明，转化过程中的第二个事件在C3H 10T1/2细胞受辐照培养物生长至汇合的过程中随机发生。当将相同数量的受辐照C3H 10T1/2细胞接种到不同大小的培养皿[35毫米(8平方厘米)、60毫米(21平方厘米)、100毫米(55平方厘米)、150毫米(145平方厘米)]中时，每个培养皿中出现的集落数取决于不同大小培养皿中汇合时的最终细胞数，使得每平方厘米的集落数是恒定的。当受辐照细胞和亲代C3H 10T1/2细胞以不同比例低密度混合时，最终出现的集落数是汇合时培养物中受辐照细胞后代数量的函数。本文给出的结果证实了先前的研究，并进一步证明细胞的辐射诱导恶性转化以间接的多阶段方式发生。
