Molecular mechanism and function research of highly expressed PEG 10 gene in hepatocellular carcinoma

Abstract

Objective: To study the molecular mechanism of dysregulation of PEG10 (paternally expressed gene 10), an imprinted gene in HCC (hepatocellular carcinoma), and to analyze its effect on the growth of hepatocellular carcinoma cells. Methods: The expression level of PEG10 mRNA was detected by semi-quantitative RT-PCR in 30 paired HCC/adjacent non-cancerous tissues and 15 types of liver cancer cell lines. Methylation status of CpG islands at the promoter of PEG10 gene in 17 paired HCC/adjacent non-cancerous tissue samples in which the expression of PEG10 gene in cancer tissues was significantly up-regulated as compared with non-cancerous tissues was detected using MSP (methylation specific PCR). The PEG10 shRNA (short hairpin RNA) was used to silence the expression of PEG10 gene in HCC QGY-7703 cells, and the colony-forming ability of QGY-7703 cells was detected by Western blotting and colony formation assay. Results: PEG10 mRNA expression level was significantly up-regulated in 67% (20/30) HCC tissues as compared with adjacent non-cancerous tissues. PEG10 was expressed in 15 types of HCC cell lines. The methylation status of PEG10 gene’s CpG2 island was significantly decreased in 29.4% (5/17) HCC tissue samples, and the overall decreased methylation status of PEG10 gene’s CpG2 island in HCC tissues was verified using bisulfite sequencing. Interestingly, silencing the expression of PEG10 in HCC QGY-7703 cells using shRNA targeting PEG10 gene markedly inhibited the colony-forming efficiency as compared with the HCC QGY-7703 cells transfected with negative control shRNA (P < 0.05). Conclusion: PEG10, an imprinted gene, is up-regulated in HCC, and may be closely related with the decreased methylation status of CpG2 island at the promoter of PEG10 gene. Silencing the expression of PEG10 can inhibit the growth of HCC cells, suggesting that PEG10 gene may play an important role in the hepatocarcinogenesis, and it may be used as a new marker or a potential therapeutic target for HCC. DOI:10.3781/j.issn.1000-7431.2013.01.005