Gong J, Traganos F, Darzynkiewicz Z
Cancer Research Institute, New York Medical College, Valhalla 10595.
Cancer Res. 1994 Jun 15;54(12):3136-9.
The protein kinase inhibitor staurosporine (SSP) stops progression of normal nontransformed cells in the G1 phase of the cell cycle. This implies that at least one of the cell cycle associated kinases, essential for cell transit through G1, is sensitive to SSP. Using multivariate flow cytometry to correlate the expression of cyclin E or cyclin D with cellular DNA content (i.e., cell cycle position), we have presently characterized the point of action of SSP in relation to the expression of these cyclins. During stimulation of normal human lymphocytes by phytohemagglutinin, cyclin D was expressed early, peaking at 8-14 h, while cyclin E appeared later, reaching a maximum at the time of cell entrance to S phase (24 h). Addition of SSP at the time of cell stimulation, while markedly suppressing the expression of cyclin E, had a rather modest effect on the expression of cyclin D. The data indicate that the SSP sensitive kinase(s) involved in cell progression through G1 operate beyond the restriction point of cyclin D but prior to that of cyclin E. Thus, the target(s) of SSP is (are) either the p33cdk/cyclin E complex itself or other protein kinase(s), activated subsequent to the cyclin D but prior to the cyclin E restriction point, the activity of which is essential for cell transit through G1.
蛋白激酶抑制剂星形孢菌素（SSP）可使正常未转化细胞在细胞周期的G1期停止进展。这意味着细胞周期相关激酶中至少有一种对于细胞通过G1期是必需的，并且对SSP敏感。我们使用多参数流式细胞术将细胞周期蛋白E或细胞周期蛋白D的表达与细胞DNA含量（即细胞周期位置）相关联，目前已经确定了SSP相对于这些细胞周期蛋白表达的作用点。在用植物血凝素刺激正常人淋巴细胞的过程中，细胞周期蛋白D早期表达，在8 - 14小时达到峰值，而细胞周期蛋白E出现较晚，在细胞进入S期（24小时）时达到最大值。在细胞刺激时加入SSP，虽然能显著抑制细胞周期蛋白E的表达，但对细胞周期蛋白D的表达影响较小。数据表明，参与细胞通过G1期进展的SSP敏感激酶在细胞周期蛋白D的限制点之后但在细胞周期蛋白E的限制点之前起作用。因此，SSP的靶点要么是p33cdk/细胞周期蛋白E复合物本身，要么是在细胞周期蛋白D之后但在细胞周期蛋白E限制点之前被激活的其他蛋白激酶，其活性对于细胞通过G1期是必需的。
