MSK1和RSK2介导的组蛋白磷酸化对人结直肠癌细胞恶性表型的影响

背景:ERK-MAPK信号通路与消化系肿瘤的发生、发展密切相关。前期研究发现抑制ERK-MAPK信号转导可能通过抑制其下游效应分子MSK1、RSK2活性而降低组蛋白H3磷酸化水平,进而下调原癌蛋白c-fos表达,抑制人结直肠癌细胞增殖。目的:探讨MSK1、RSK2与组蛋白磷酸化对人结直肠癌细胞肿瘤相关基因表达和恶性表型的影响。方法:以不同浓度ERK-MAPK阻断剂U0126干预人结肠癌细胞株HCT1 16和SW11 16,或以RNA干扰技术靶向沉默细胞中的MSK1、RSK2表达,分别采用CCK-8实验、流式细胞分析和蛋白质印迹法检测经不同处理的肿瘤细胞的增殖情况、细胞周期分布以及MSK1、RSK2磷酸化位点、组蛋白H3磷酸化水平和MSK1、RSK2、c-fos蛋白表达。结果:U0126能阻断人结直肠癌细胞MSK1(Thr581)、RSK2(Ser386)的磷酸化活化,转染MSK1 siRNA或RSK2 siRNA能特异性抑制MSK1、RSK2表达,导致组蛋白H3(Set10)磷酸化水平降低,c-fos蛋白表达下调,肿瘤细胞发生G0/G1期阻滞,细胞增殖显著受抑(P均<0.05)。结论:阻断ERK-MAPK信号转导可能通过抑制MSK1(Thr581)、RSK2(Ser386)磷酸化活化及其介导的组蛋白H3磷酸化而下调肿瘤相关基因如c-fos表达,从而抑制人结直肠癌细胞的恶性表型。

Effect of MSK1 and RSK2 Mediated Histone Phosphorylation on Malignant Phenotype of Human Colorectal Cancer Cells

ERK-MAPK signal pathway is considered to be closely related with the tumorigenesis of digestive system. Previous study has demonstrated that inhibition of ERK-MAPK signal transduction might reduce histone H3 phosphorylation via suppression of its downstream effectors, MSK1 and RSK2, and subsequently down-regulated c-fos oncoprotein expression, which resulted in the inhibition of human colorectal cancer cell proliferation. Aims ： To investigate the effect of MSK1, RSK2 and histone phosphorylation on tumor-related gene expression and malignant phenotype of human colorectal cancer cells. Methods： Human colon cancer cell lines HCT116 and SW1116 were treated with gradient doses of ERK-MAPK signal pathway inhibitor U0126, or interfered with siRNAs for silencing MSK1 and RSK2 expression. Cell proliferation was determined by CCK-8 assay; cell cycle distribution was assessed by flow eytometry; phosphorylation sites and expression levels of MSKI, RSK2 and histone H3, as well as the c-fos protein expression were detected by Western blotting. Results： Phosphorylations of MSK1 （Thr581） and RSK2 （Ser386） were reduced obviously in human colorectal cancer cells treated with U0126. MSK1 siRNA and RSK2 siRNA transfection inhibited effectively and specifically the expressions of MSK1 and RSK2, which decreased histone H3 （Serl0） phosphorylation and c-fos protein expression, and subsequently led to cell cycle arrest in G0/G1 phase and significant inhibition of cell proliferation （ P all 〈 0.05 ）. Conclusions： Inhibition of ERK-MAPK signal transduction suppresses MSK1 （Thr581） and RSK2 （Ser386） phosphol＇ylation and activation and their mediated histone H3 phosphorylation, which may down-regulate tumor related gene （e. g. c-fos） expression and ultimately restrains the malignant phenotype of human coloreetal cancer cells.