Narayanan P K, Rudnick J M, Walthers E A, Crissman H A
Life Sciences Division, Los Alamos National Laboratory, New Mexico 87545, USA.
Exp Cell Res. 1997 May 25;233(1):118-27. doi: 10.1006/excr.1997.3549.
The comparative effects of staurosporine or caffeine on G2-phase arrest and cyclin B1 expression in human skin fibroblasts (HSF) and transformed HeLa cells following gamma-irradiation were examined by flow cytometry. Contrary to some earlier reports with HeLa cells, the arrest in G2 after irradiation was accompanied by an increase in cyclin B1 levels in both asynchronous and synchronized HeLa cells irradiated in early S phase. Caffeine and staurosporine were equally effective in attenuating both the radiation-induced increase in cyclin B1 expression and the prolongation of G2 in synchronous and asynchronous HeLa cell populations. Staurosporine treatment was less effective in down-regulating cyclin B1 expression in asynchronous HeLa cells at earlier time points following irradiation when compared to caffeine-treated cells. In synchronized HeLa cells, down-regulation of an irradiation-induced increase in cyclin B1 expression was similar to either staurosporine or caffeine treatments, with caffeine being more effective at later time points. An increase in cyclin B1 expression was also observed in irradiated HSF cells (synchronous and asynchronous), which decreased when the cells were treated with staurosporine or caffeine. However, staurosporine was ineffective in attenuating the radiation-induced prolongation of G2 in synchronous and asynchronous HSF cells, whereas treatment of irradiated synchronous or asynchronous HSF cells with caffeine significantly reduced the prolongation of G2. These results suggest that both staurosporine and caffeine treatments act on different pathways of cell cycle control in normal and transformed cells, in terms of attenuation of G2 block and diminution of elevated levels of cyclin B1 expression, in response to radiation.
通过流式细胞术检测了星形孢菌素或咖啡因对γ射线照射后人皮肤成纤维细胞（HSF）和转化的HeLa细胞中G2期阻滞和细胞周期蛋白B1表达的比较效应。与一些早期关于HeLa细胞的报道相反，在早期S期照射的异步和同步HeLa细胞中，照射后G2期阻滞伴随着细胞周期蛋白B1水平的增加。咖啡因和星形孢菌素在减弱辐射诱导的细胞周期蛋白B1表达增加以及同步和异步HeLa细胞群体中G2期延长方面同样有效。与咖啡因处理的细胞相比，在照射后的早期时间点，星形孢菌素处理在下调异步HeLa细胞中细胞周期蛋白B1表达方面效果较差。在同步HeLa细胞中，照射诱导的细胞周期蛋白B1表达增加的下调与星形孢菌素或咖啡因处理相似，咖啡因在后期时间点更有效。在照射的HSF细胞（同步和异步）中也观察到细胞周期蛋白B1表达增加，当用星形孢菌素或咖啡因处理细胞时，该表达降低。然而，星形孢菌素在减弱同步和异步HSF细胞中辐射诱导的G2期延长方面无效，而用咖啡因处理照射的同步或异步HSF细胞则显著减少了G2期延长。这些结果表明，就响应辐射时G2期阻滞的减弱和细胞周期蛋白B1表达升高水平的降低而言，星形孢菌素和咖啡因处理在正常细胞和转化细胞中作用于细胞周期控制的不同途径。
