Study On The Mechanism Of E-cadherin Expression In Gastric Cancer Cells

OBJECTIVE:To explore the internal mechanisms which contribute to the different expression of E-cadherin in normal gastric mucosal epithelial cells,bronchial epithelial cells and gastric cancer cells,lung cancer cells.METHODS:GES-1(normal gastric mucosal epithelial cell), SGC-7901, MGC-803, BGC-823(three gastric cancer cells),HBE (normal bronchial epithelial cell) and A549(lung cancer cell) were selected for the research. The expression of E-cadherin was examined at the mRNA level using RT-PCR and at the protein level using Western Blot.The methylation level of E-cadherin promoter region was detected by the methods of MSP (methylation-specific PCR) and BSP (bisulfite sequencing PCR). Treat these cells with5-Azacytidine (methyltransferase inhibitor) in order to examine a further link between methylation and its gene expression.After the drug treatment, detect the expression of E-cadherin.RESULTS:The expression of E-cadherin was detected only in HBE, not in other five cell lines. The results of MSP demonstrated that methylations of E-cadherin promoter region existed in four cancer cell lines but not in two normal cell lines. BSP results confirmed it. After the drug treatment of5-Azacytidine, the expression of E-cadherin on mRNA level was restored in all the four cancer cell lines while the drug had no effect on the two normal epithelial cell lines.CONCLUTIONS:The expression of E-cadherin in six cell lines was different. The absence of E-cadherin in four cancer cells may be related to the gene promoter hypermethylation. But the negtative expression of E-cadherin in GES-1was not the outcome of promoter methylation. Accurate quantification of methylation status of some genes can be obtained by the method of BSP combined with TA clone sequencing.