Promoter methylation inhibits SCCA1 expression in nasopharyngeal carcinoma cells

Squamous cell carcinoma antigen 1 (SCCA1) is implicated in the growth, differentiation and metastasis of squamous cell carcinoma. Previously we found that SCCA1 protein level was lower in nasopharyngeal carcinoma (NPC) than in nasopharyngeal epithelial tissue. This study aimed to investigate the mechanism by which SCCA1 expression is downregulated in NPC. Four NPC cell lines including CNE1, CNE2, 5-8F, 6-10B, and immortalized nonneoplastic human nasopharyngeal epithelial cell line NP69 were cultured in vitro. Methylation of SCCA1 promoter was detected by methylation specific polymerase chain reaction, and mRNA expression level was detected by reverse transcriptional polymerase chain reaction. Subsequently, NPC cell lines were treated with different concentration (0, 0.1, 1, 5 and 10 μmol/L) of 5-aza-2’-deoxycytidine (5-aza-2dC) for 72 h. Methylation status and mRNA and protein expression of SCCA1 gene were detected. The results showed that SCCA1 promoter was methylated in all four NPC cell lines but not in NP69 cell line, and methylation status was correlated with SCCA1 expression level as well as the differentiation and metastasis potential of the cells. 5-aza-2dC reversed SCCA1 promoter methylation and increased mRNA and protein expression levels of SCCA1 in all four NPC cell lines. In conclusion, SCCA1 promoter is methylated in NPC cells and contributes to the downregulation of SCCA1 in NPC.