Epigenetic silencing of microRNA-335 contributes to nasopharyngeal carcinoma metastasis

MircoRNA-335 (miR-335), a member of mircoRNAs (miRNAs) family, has been found to be correlated with tumor invasion and metastasis. In this study, we aimed to detect the effect of miR-335 methylation on metastasis of nasopharyngeal carcinoma. RT-PCR and methylation-specific PCR were applied to detect the expression levels of miR-335 and miR-335 methylation in nasopharyngeal carcinoma tissues. The levels of miR-335 expression were significantly lower in nasopharyngeal cancer tissues with promoter methylation, compared to those with promoter unmethylation. The levels of miR-335 gene promoter methylation were higher in 14 (46.7%) out of 30 nasopharyngeal cancer tissues. Furthermore, the patients with cervical lymph node metastasis had higher methylation rate in miR-335 promoter (66.7% versus 16.7%) than those without cervical lymph node metastasis. Gene methylation contributes the expression of miR-335 in nasopharyngeal carcinoma. The expression of miR-335 methylation is correlated with the metastasis of nasopharyngeal carcinoma.