STAT3介导了血小板源性生长因子BB诱导的大鼠血管平滑肌细胞Pim-1表达

 目的： 观察血小板源性生长因子BB(PDGF-BB)是否可以诱导大鼠血管平滑肌细胞（VSMCs）表达Pim-1及Pim-1对VSMCs增殖的影响，探讨STAT3信号分子在这一过程中的作用，为血管重建性疾病（VRD）的研究提供实验依据。方法： 不同浓度PDGF-BB作用不同时间刺激体外培养的VSMCs，用细胞计数法检测增殖；用real-time RT-PCR 检测Pim-1 mRNA表达水平；Western blotting 检测STAT3 的活性变化；用放线菌素D（actinomycin D）、AG490（JAK特异性抑制剂）及siRNA沉默Pim-1和STAT3进行干预。结果： PDGF-BB（20 μg/L）作用VSMCs 24 h，可以诱导细胞增殖，Pim-1沉默抑制了这一过程；正常未经处理的VSMCs Pim-1 mRNA表达量较低，不同浓度PDGF-BB（10 μg/L~50 μg/L ）作用VSMCs 1 h，Pim-1 mRNA表达明显增加，其中以20 μg/L最显著；用PDGF-BB（20 μg/L）作用VSMCs 不同时间（0.5 h~4 h），可显著上调Pim-1 mRNA表达，以0.5 h最显著。用actinomycin D及AG490预处理后Pim-1 mRNA表达随之降低。PDGF-BB可激活VSMCs中磷酸化STAT3水平，AG490和转染STAT3-siRNA可抑制 STAT3的磷酸化以及相应的Pim-1 mRNA表达。结论： PDGF-BB可通过Pim-1调节VSMCs增殖；STAT3可能参与了PDGF-BB诱导的VSMCs Pim-1表达。

STAT3 mediates PDGF-BB-induced Pim-1 expression in rat vascular smooth muscle cells

AIM: To study Pim-1 expression in VSMCs induced by platelet-derived growth factor BB (PDGF-BB) and the dependent signaling pathway. METHODS: VSMCs isolated from rats were treated with PDGF-BB at different concentration and durations. Proliferation of VSMCs was detected by Cell counting. The expression of Pim-1 mRNA was detected by real-time RT-PCR. The STAT3 activity was detected by Western blotting. Actinomycin D, AG490, and small interfering RNA (siRNA) for Pim-1 or STAT3 were used to investigate underlying mechanisms. RESULTS: Pim-1 gene silencing attenuated proliferation of VSMCs in response to PDGF-BB. Pim-1 mRNA expression was up-regulated by PDGF-BB for 1 h at 10 μg/L ~ 50 μg/L, and maximally induced at 20 μg/L. The time of Pim-1 mRNA expression maximally occurred 30 min after PDGF-BB exposure. Incubation of VSMCs with PDGF-BB resulted in a significant activation of STAT3. VSMCs pretreated with actinomycin D showed a significant decrease Pim-1 mRNA expression. Treatment with AG490 or knockdown STAT3 in VSMCs resulted in inactivation of STAT3, meanwhile, significantly suppressed Pim-1 mRNA expression. CONCLUSION: PDGF-BB-induced VSMC proliferation is partly attributed to Pim-1 gene. VSMCs strongly increased Pim-1 mRNA upon stimulation with PDGF-BB, and STAT3 signaling pathway appears to be efficient for regulation Pim-1 expression. This process may play a critical role in development of vascular remodeling.