14-3-3 sigma Promoter de-methylation and gene expression in nasopharyngeal carcinoma cell lines / 国际肿瘤学杂志

ABSTRACT

Objective To investigate the methylation status of 14-3-3σ promoter in nasopharyngeal carcinoma cell lines and the influence of de-methylation treatment on 14-3-3σ expression. Methods Methylation status of 14-3-3σ gene promoter and 14-3-3σ mRNA expression were detected by methylation specific PCR (MSP) and RT-PCR in nasopharyngeal carcinoma cell lines CNE1, CNE2,5-8F,6-10B and immortalized nonneoplastic human nasopharyngeal epithelial cell line, NP69. Four nasopharyngeal carcinoma cell lines were treated with 5-asa-2' -deoxycytidine(5-aza-2dC) in different concentration for 72 h, then 14-3-3σ promoter meth-ylation status and m RNA expression were assessed, and western-blot was performed to detect the expression of 14-3-3σ protein. Results 14-3-3σ promoter methylation was detected by MSP in all of the four nasopharyn-geal carcinoma cell lines untreated by 5-aza-2dC whereas not in the treated ones or the immortalized human na-sopharyngeal epithelial cell line, NP69. Accordingly, 14-3-3σ mRNA expression was significantly discounted in untreated nasopharyngeal carcinoma cell lines as compared with NP69. 5-aza-2dC treatment dose-depend-ently reversed 14-3-3σ promoter methylation status and consequently upregulated the expression of 14-3-3σmRNA and protein in 4 nasopharyngeal carcinoma cell lines. High-differentiated CNE1 was more sensitive to 5-aza-2dC than lowly-differentiated CNE2, 5-8F and 6-10B. Conclusion Promoter methylation directly leads to decreased 14-3-3σ gene expression in nasopharyngeal carcinoma cell lines, and 14-3-3σ promoter de-methylation perhaps indicates a new target for nasopharyngeal carcinoma treatment.