MicroRNA-377和组蛋白甲基转移酶SMYD3在肝细胞癌中的表达及两者的相关性

Correlation between microRNA-377 and histone methyltransferase SMYD3 expression in hepatocellular carcinoma

目的:探讨microRNA-377(miR-377)与组蛋白甲基转移酶SMYD3在肝癌中的表达规律及与肝癌的相关性.方法:利用实时定量PCR分别检测不同肝组织及肝细胞系中miR-377表达水平,应用实时定量PCR和Western blot分别检测不同肝组织及肝细胞系中SMYD3 mRNA和蛋白水平的表达情况.通过转染miR-377模拟物上调其在肝癌细胞株HepG2中表达后,应用实时定量PCR、Western blot分别检测转染前后HepG2中SMYD3 mRNA和蛋白表达的变化.结果:MiR-377 mRNA在人肝癌旁组织和肝癌组织中的表达较正常肝脏明显降低(0.331±0.059,0.139±0.064 vs 0.874±0.178,均P<0.05);在HepG2中的表达较L-02明显降低(0.145±0.021vs0.868±0.194,P<0.05).SMYD3 mRNA和蛋白质在人肝癌旁组织和肝癌组织中的表达较正常肝脏明显升高(mRNA:3.836±0.137,5.836±0.965vs1.235±0.332;蛋白:0.381±0.020,0.484±0.030vs0.252±0.015;均P<0.05).SMYD3 mRNA和蛋白质在肝癌细胞系HepG2中的表达较正常肝细胞系L-02明显升高(mRNA:0.845±0.047vs0.348±0.134;蛋白:0.575±0.008vs0.259±0.007,均P<0.05).转染miRNA-377模拟物上调HepG2中miR-377表达后转染组SMYD3 mRNA和蛋白表达较空白组和阴性对照组均明显下降(mRNA:0.125±0.010 vs 0.857±0.163,0.779±0.167;蛋白:0.092±0.026 vs 0.347±0.040,0.383±0.054,均P<0.05).结论:miRNA-377在肝癌中表达明显下调,其靶基因SMYD3表达上调;表达下调的miRNA-377丧失对SMYD3表达的抑制可能是肝癌发生的重要机制.

AIM：To investigate the expression of microRNA-377 （miR-377） and histone methyltransferase SMYD3 in hepatocellular carcinoma （HCC） and to analyze their correlation.METHODS：Quantitative real-time PCR was performed to detect miR-377 expression in dif-ferent liver tissues and cell lines.Quantitative real-time PCR and Western blot were employed to detect the expression of SMYD3 （a target gene of miR-377） mRNA and protein, respectively.After transfection of HepG2 cells with a miR-377 mimic, quantitative real-time PCR and Western blot were used to detect the expression of SMYD3 mRNA and protein, respectively.RESULTS：MiR-377 mRNA was underexpressed in HCC and tumor-adjacent tissue compared to normal liver tissue （0.331±0.059 and 0.139±0.064 vs 0.874±0.178, both P0.05）.MiR-377 mRNA was also underexpressed in HepG2 cells compared to L-02 cells （0.145±0.021 vs 0.868±0.194, P0.05）.SMYD3 mRNA and protein were over-expressed in HCC and tumor-adjacent tissue compared to normal liver tissue （mRNA：3.836±0.137 and 5.836±0.965 vs 1.235±0.332, both P0.05; protein：0.381±0.020 and 0.484±0.030 vs 0.252±0.015, both P0.05）.SMYD3 mRNA and protein were overexpressed in HepG2 cells compared to L-02 cells （mRNA：0.845±0.047 vs 0.348±0.134, P0.05; protein：0.575±0.008 vs 0.259±0.007, P0.05）.SMYD3 mRNA and protein expression in HepG2 cells was down-regulated after transfection of an miR-377 mimic （mimic vs empty control negative control：mRNA, 0.125±0.010 vs 0.857±0.1635 and 0.779±0.167; protein, 0.092±0.026 vs 0.347±0.040 and 0.383±0.054; all P0.05）.CONCLUSION：miR-377 is down-regulated and its target gene SMYD3 is overexpressed in HCC, which suggests that miR-377 down-regulation promotes the carcinogenesis of hepa-tocellular carcinoma by up-regulating SMYD3 expression.