Abstract: Objective To investigate the promoter methylation and expression level of TBX15 gene in hepatoma cells，and explore the effect of promoter methylation on its mRNA expression and cell tumor behavior. Methods Bisulfite sequencing PCR （BSP） and quantitative real-time PCR（qPCR） were used to detect the promoter methylation and expression level of TBX15 in three hepatocellular carcinoma cell lines（HepG2，MHCC97H，SNU449）. Then the blank plasmid，empty plasmid pc3.1 and TBX15 overexpression plasmid were transfected into the hepatoma cell SNU449，and the proliferation and apoptosis in three different groups of hepatoma cells were detected by CCK-8 assay and flow cytometry. Results Among the three hepatocellular carcinoma cell lines，the TBX15 gene had the highest promoter methylation rate（89.5%） and the lowest mRNA expression level in SNU449 hepatoma cell. The overexpression plasmid group proliferating for hepatoma cells after culturing 48 h was higher than that of the empty plasmid group. The difference was statistically significant（0.549±0.080 vs 0.457±0.506，P=0.015）. The results of total apoptosis counting showed that the overexpression plasmid group had a higher effect on the apoptosis ability of hepatoma cells than the blank plasmid group. The difference was statistically significant［（5.12±1.42）% vs （2.16±0.41）%，P=0.014］. Conclusions Abnormal methylation in the promoter region may be the main reason for the inactivation of TBX15 gene，and it was closely related to the malignant biological behavior of hepatocellular carcinoma. It was a predictor for the progression of hepatocellular carcinoma.

Key words: Hepatocellular carcinoma, TBX15, Promoter methylation, Proliferation, Apoptosis