[摘 要] 目的：探讨miRNA-490-3p调控Smad2/TGF-β对结直肠癌奥沙利铂化疗敏感性的影响。方法：选取100例结直肠癌（colorectal cancer，CRC）根治性手术后奥沙利铂（oxaliplatin，OXA）同种联合化疗患者作为研究对象，根据化疗情况分为耐药组（n=40）和非耐药组（n=60），用qPCR检测两组外周血miRNA-490-3p水平；选取人CRC细胞株SW480和CRC OXA耐药型细胞株OXA-SW480进行研究，先用qPCR检测两种细胞株中miRNA-490-3p表达水平；后将miRNA-490-3p过表达载体转染OXA-SW480（过表达组），并设立空载体组（空载体转染OXA-SW480）和空白对照组（OXA-SW480未经任何处理）。用CCK-8检测各组细胞增殖能力，同时用不同浓度OXA处理各组细胞，计算其半数抑制浓度（IC50）；用Annexin Ⅴ-FITC/PI染色流式细胞术检测各组细胞凋亡率；用WB检测各组Smad2和TGF-β蛋白表达水平。结果：在CRC患者中，耐药组外周血miR-490-3p水平显著低于非耐药组，在CRC细胞株中，OXA-SW480耐药株细胞miR-490-3p水平显著低于正常株SW480细胞（P<0.05）。与空载体组和空白对照组相比，过表达组miR-490-3p水平显著升高（均P<0.05），增殖抑制率显著升高（均P<0.01），细胞凋亡率显著升高（均P<0.01），Smad2蛋白水平显著降低（均P<0.05），TGF-β蛋白水平显著升高（均P<0.05）。经OXA处理后，过表达组的IC50显著低于空载体组和空白对照组（均P<0.01）。经Pearson相关法分析，miR-490-3p与Smad2的表达呈负相关（r=–0.943，P<0.01），miR-490-3p与TGF-β的表达呈正相关（r=0.961，P<0.01）。结论：过表达miRNA-490-3p可增加CRC SW480细胞的OXA敏感性，此作用与Smad2/TGF-β信号通路有关。

[Abstract] Objective: To investigate the effect of miRNA-490-3p regulating Smad2/TGF-β on chemo-sensitivity of colorectal cancer to oxaliplatin. Methods: One hundred patients with colorectal cancer (CRC) who received oxaliplatin (OXA) chemotherapy after radical operation were selected as research subjects and divided into drug resistant group (n=40) and non-resistant group (n=60) according to the chemotherapy outcome. The level of miRNA-490-3p in peripheral blood of two groups of patients was detected by qPCR. Human CRC cell line SW480 and oxaliplatin resistant CRC cell line OXA-SW480 were selected for the study. The expression level of miRNA-490-3p in the two cell lines was detected by qPCR, and then the miRNA-490-3p over-expression vector was transfected into OXA-SW480 cells (over-expression group), in the meanwhile, the empty vector group (OXA-SW480 cells transfected with empty vector) and blank control group (OXA-SW480 cells without any treatment) were set up. CCK-8 was used to detect cell proliferation ability of each group, and different concentrations of OXA were used to treat cells of each group to calculate the half inhibitory concentration (IC50); Annexin Ⅴ-FITC/PI staining was used to detect cell apoptosis rate of each group; WB assay was used to detect the expression levels of Smad2 and TGF-β. Results: In CRC patients, the level of miR-490-3p in the peripheral blood of the drug-resistant group was significantly lower than that of the non-resistant group. In the CRC cells, the level of miR-490-3p in the OXA-SW480 cells was significantly lower than that of the normal SW480 cells (P<0.05). Compared with the empty vector group and the blank control group, the level of miR-490-3p in the over-expression group was significantly increased (all P<0.05), the proliferation inhibition rate and the apoptosis rate were significantly increased (all P<0.05), Smad2 protein level was significantly reduced (all P<0.05), and TGF-β protein level was significantly increased (all P<0.05). After OXA treatment, the IC50 of the over-expression group was significantly lower than that of the empty vector group and the blank control group (both P<0.05). According to the results of Pearson correlation analysis, the expression of miR-490-3p was negatively correlated with the expression of Smad2 (r=–0.943, P<0.01), but positively correlated with the expression of TGF-β (r=0.961, P<0.01). Conclusion: Over-expression of miRNA-490-3p can increase the OXA sensitivity of CRC SW480 cells, which is related to the Smad2/TGF-β signaling pathway.

广东省医学科技技术研究基金资助项目（No.A2016500）；广东省自筹经费类科技计划资助项目（No.2017ZC0250）