Department of Biochemical Science and Technology, National Chiayi University, Chiayi 600, Taiwan.
Ann Hematol. 2011 Sep;90(9):1017-29. doi: 10.1007/s00277-011-1186-3. Epub 2011 Feb 18.
The induction of megakaryocyte (MK) differentiation is a potent strategy for the clinical treatment of diseases related to blood platelet disorders. Staurosporine (STS) is an inhibitor of protein kinase C (PKC) with an inhibitory effect on cancer cells through apoptosis induction. However, the exact mechanism of STS on MK differentiation is still unclear. The present study assessed the regulatory effect of STS on MK differentiation in both human leukemia cells and mouse bone marrow-derived stem cells. STS not only inhibited the proliferation of both K562 and HEL cell lines, but also induced the cell differentiation into MK lineage, resulting in polyploidy formation, MK-specific markers CD41 and CD61 expression, and platelet factor 4 (PF4) secretions of cells. The induction effect of STS was upregulated through the expression of Stat3, but not PKC. The level of phosphorylated (p)-Stat3 showed an increased expression, translocated to the nucleus, and enhanced the DNA-binding activity in STS-treated cells. Blockage Stat3 and its upstream molecule JAK by Stat3 inhibitor VI and JAK inhibitor I, respectively, demonstrated that the cells obviously reduced the percentage of STS-mediated MK differentiation. Further investigation of the cells with Stat3 siRNA transfection showed that p-Stat3 and MK differentiation was markedly decreased, indicating that Stat3 is an important molecule in inducing MK differentiation. Additionally, the ex vivo assay also confirmed that STS effectively stimulated CFU-MK colony formation and CD61 expression in bone marrow cells. In conclusion, STS is a potent inducer for MK differentiation through the upregulation of JAK/Stat3 signaling pathway and p-Stat3 nuclear translocation.
巨核细胞（MK）分化的诱导是治疗与血小板紊乱相关疾病的有效策略。Staurosporine（STS）是蛋白激酶 C（PKC）的抑制剂，通过诱导细胞凋亡对癌细胞具有抑制作用。然而，STS 对 MK 分化的确切机制尚不清楚。本研究评估了 STS 对人白血病细胞和小鼠骨髓源性干细胞中 MK 分化的调节作用。STS 不仅抑制 K562 和 HEL 细胞系的增殖，还诱导细胞向 MK 谱系分化，导致多倍体形成、MK 特异性标记物 CD41 和 CD61 的表达以及细胞分泌血小板因子 4（PF4）。STS 的诱导作用通过 Stat3 的表达上调，但不通过 PKC。磷酸化（p）-Stat3 的水平表达增加，转位到细胞核，并增强 STS 处理细胞中的 DNA 结合活性。分别用 Stat3 抑制剂 VI 和 JAK 抑制剂 I 阻断 Stat3 和其上游分子 JAK，结果表明细胞明显减少了 STS 介导的 MK 分化的百分比。用 Stat3 siRNA 转染细胞的进一步研究表明，p-Stat3 和 MK 分化明显减少，表明 Stat3 是诱导 MK 分化的重要分子。此外，体外实验也证实 STS 可有效刺激骨髓细胞 CFU-MK 集落形成和 CD61 表达。总之，STS 通过上调 JAK/Stat3 信号通路和 p-Stat3 核转位，是一种有效的 MK 分化诱导剂。
