Traganos F, Gong J, Ardelt B, Darzynkiewicz Z
Cancer Research Institute, New York Medical College, Elmsford 10523.
J Cell Physiol. 1994 Mar;158(3):535-44. doi: 10.1002/jcp.1041580320.
Staurosporine (SSP) is an inhibitor of a variety of protein kinases with an especially high affinity towards protein kinase C. Whereas SSP has been shown to halt the cell cycle progression of various normal, nontransformed cell types in G1, most virus transformed or tumor cells are unaffected in G1 but arrest in G2 phase. SSP has also been observed to increase the appearance of cells with higher DNA content, suggestive of endoreduplication, in cultures of tumor cells. Using multivariate flow cytometry (DNA content vs. expression of cyclin B, nuclear p120 protein, or protein reactive with Ki-67 antibody) which makes it possible to discriminate cells with identical DNA content but at different phases of the cycle, we have studied the cell cycle progression of human lymphocytic leukemic MOLT-4 cells in the presence of 0.1 microM SSP. MOLT-4 cells did not arrest in G1 or G2 phase in the presence of the inhibitor. Rather, they failed to undergo cytokinesis, entering G1 phase at higher DNA ploidy (tetraploidy; G1T), and then progressed through ST (rereplication) into G2T and MT. The rates of entrance to G2 and G2T were essentially identical, indicating that the rates of cell progression through S and ST as well as through G2 and G2T, respectively, were similar. Cells entrance to mitosis and mitotic chromatin condensation were also similar at the diploid and tetraploid DNA content level and were unaffected by 0.1 microM SSP. No evidence of growth imbalance (altered protein or RNA to DNA ratio) was observed in the case of tetraploid cells. The data show that, in the case of MOLT-4 cells, all events associated with the chromosome or DNA cycle were unaffected by SSP; the only target of the inhibitor appears to be kinase(s) controlling cytokinesis.
星形孢菌素（SSP）是多种蛋白激酶的抑制剂，对蛋白激酶C具有特别高的亲和力。虽然已表明SSP能使各种正常的、未转化的细胞类型在G1期停止细胞周期进程，但大多数病毒转化细胞或肿瘤细胞在G1期不受影响，而是在G2期停滞。在肿瘤细胞培养物中也观察到SSP会增加DNA含量较高的细胞的出现，这提示了核内复制。使用多参数流式细胞术（DNA含量与细胞周期蛋白B、核p120蛋白或与Ki-67抗体反应的蛋白的表达），可以区分DNA含量相同但处于细胞周期不同阶段的细胞，我们研究了在存在0.1微摩尔SSP的情况下人淋巴细胞白血病MOLT-4细胞的细胞周期进程。在存在抑制剂的情况下，MOLT-4细胞不会在G1期或G2期停滞。相反，它们未能进行胞质分裂，在更高的DNA倍性（四倍体；G1T）下进入G1期，然后通过ST（再复制）进入G2T和MT。进入G2和G2T的速率基本相同，这表明细胞分别通过S和ST以及通过G2和G2T的进程速率相似。在二倍体和四倍体DNA含量水平下，细胞进入有丝分裂和有丝分裂染色质凝聚也相似，并且不受0.1微摩尔SSP的影响。在四倍体细胞中未观察到生长失衡（蛋白质或RNA与DNA比例改变）的证据。数据表明，对于MOLT-4细胞，所有与染色体或DNA周期相关的事件均不受SSP影响；该抑制剂的唯一靶点似乎是控制胞质分裂的激酶。
