Effect Of The Methylation Of Syk Gene Promoter In Hepatocellular Carcinoma Cell Lines On Invasion

Objective: To investigate the methylation status of Syk gene promoter in hepatocellular carcinoma cell lines and their effect on cell invasion. To identify the expression of Syk in MHCC97H, MHCC97L, HepG2 and L02,and to identify the methylation status of Syk gene in these cell lines. To study the relationship between the methylation and silencing of Syk gene. To compare the invasion of HCC cell lines before and after the treatment of methyltransferase inhibitor.Methods: MHCC97H, MHCC97L, HepG2 and L02 were cultured in vitro. By using RT- PCR and MSP methods, the expression and the methylation status of Syk gene were detected in L02, HepG2, MHCC97H and MHCC97L respectively. Syk methylation-positive cell lines were treated with a DNA methyltransferase (DNMT) inhibitor 5-aza-2′deoxycytidine (5-Aza-CdR). The expression of Syk gene of them were also detected by MSP technique before and after the treatment. Cell invasions and motilities in these cell lines were evaluated by Transwell chamber assay in Syk methylation-positive cell lines before and after a treatment with 5-Aza-CdR. The cell numbers which passed through the Transwell membrane were counted as the indicators of cell invasions in vitro.Results: Syk was expressed in L02 and MHCC97L,and was silenced in MHCC97H and HepG2. Syk was methylated in MHCC97H and HepG2, and unmethylated in L02 and MHCC97L. After treating with 5-Aza-CdR, the transcription of Syk was reactivated in MHCC97H and HepG2, and the cell numbers which passed through the Transwell membrane were significantly decreased (P < 0. 001).Conclusions:1. Syk gene is slient in HCC cells. The aberrant methylation may be responsible for the loss of Syk expression in HCC cells.2. The aberrant methylation and silencing of Syk gene mostly happen in HCC cell lines with high metastatic potential. This indicates that the methylation status of Syk gene is related to the invasiveness of HCC cells. Syk may inhibit the invasive ability of HCC cells in vitro.3. Demethylation drugs like 5-Aza-CdR can effectively reverse the methylation status of Syk gene.