Study on promoter methylation status of E-cadherin gene in nasopharyngeal carcinoma cell lines

Abstract

To investigate the role of methylation on E-cadherin inactivation in nasopharyngeal carcinoma (NPC) cell line HNE1 and CNE2, as well as evaluate the inhibitory effect of 5-aza-2'-deoxycytidine (5-Aza-dC) on cell abilities of proliferation and invasion. The expression level of E-cadherin was measured by RT-PCR, Western blot and immunohistochemistry (polymer method), the methyaltion status was analyzed by methylation-specific PCR (MSP), and cell proliferation and invasion were examined by MTT and invasion assay, separately before and after treatment with demethylating agent 5-Aza-dC. The expression level of E-cadherin was down-regulated compared with the normal tissue, simultaneously partially methylated in gene promoter. Treatment with 20 µmol/L 5-Aza-dC increased the expression of E-cadherin and reduced the methylation degree. Moreover, it also significantly suppressed cell growth (27.6% for HNE1 cells and 34.3% for CNE2 cells, P < 0.05) and invasiveness (37.2% for HNE1 cells and 29.7% for CNE2 cells, P < 0.05). Aberrant methylation around gene promoter region may play an important part in down regulation of E-cadherin in NPC, suggesting a potential therapeutic strategy for demethylating agents such as 5-Aza-dC.