The effect of N-ethylmaleimide on the response to x rays of synchronized HeLa cells.
The effect of N-ethylmaleimide on the response to x rays of synchronized HeLa cells.
复制标题
N-乙基马来酰亚胺对同步 HeLa 细胞 X 射线响应的影响。
作者：
A. Han;W. K. Sinclair;B. Kimler
在同步 HeLa 细胞周期不同阶段的照射过程中，0.75 $mu$M N-乙基马来酰亚胺 (NEM) 的存在增强了 G$sub 1$ 早期和 S 晚期的细胞杀伤（即敏化），但不影响有丝分裂细胞或 G$sub 1$/S 边界的细胞。影响主要集中在生存曲线的肩部，而不是其斜率。在照射之前或之后立即给予 NEM 与照射期间一样有效。当作为暴露后时间的函数给出时，效果会减弱，S 中的细胞比 G$sub 1$ 中的细胞对 NEM 变得不敏感的速度更快。如果在辐射之前施用该药物也有效，但治疗和辐射之间的间隔越长，效果通常会降低。向 G$sub 1$ 中的同步 HeLa 细胞添加 1.0 mM 羟基脲 (HU) 表明，即使在没有 DNA 合成的情况下，随着细胞进入细胞周期，存活率也会发生变化。观察到的变化与之前在中国仓鼠细胞中观察到的变化在性质上相同。在 0.75 $mu$M NEM 存在的情况下，对 HU 抑制的细胞进行照射，在整个周期中的存活率几乎没有变化，受抑制的细胞表现出比有丝分裂细胞中通常观察到的更高的敏感性。所得出的结果与 NEM 抑制细胞修复过程的观点一致，很可能是由于它与与辐射损伤修复有关的关键的含 SH 酶结合。 （授权）« 少
The presence of 0.75 $mu$M N-ethylmaleimide (NEM) during irradiation of synchronous HeLa cells at different stages of their cycle enhances cell killing (i.e., sensitizes) in early G$sub 1$ and late S, but does not affect mitotic cells or cells at the G$sub 1$/S border. The effect is primarily on the shoulder of the survival curve, rather than its slope. NEM given immediately before or after irradiation is as effective as during irradiation. When given as a function of time after exposure the effect decreases in magnitude, cells becoming insensitive to NEM more rapidly in S than in G$sub 1$. The drug is also effective if administered prior to irradiation, the effect generally decreasing the longer the interval between treatment and irradiation. The addition of 1.0 mM hydroxyurea (HU) to synchronous HeLa cells in G$sub 1$ showed that survival changes occur as the cells proceed through the cell cycle even in the absence of DNA synthesis. The changes observed are qualitatively the same as those observed previously in Chinese hamster cells. The irradiation of HU-inhibited cells in the presence of 0.75 $mu$M NEM produced almost no variation in survival through the cycle, the inhibited cells showing a sensitivity greater than thatmore » normally observed in mitotic cells. The results presented are consistent with the idea that NEM inhibits repair processes in the cell most likely due to its binding to a critical SH-containing enzyme(s) concerned with the repair of radiation damage. (auth)« less