Kank1 reexpression induced by 5-Aza-2'-deoxycytidine suppresses nasopharyngeal carcinoma cell proliferation and promotes apoptosis.

Kank1, which was first described as a potential tumor suppressor for renal cell carcinoma (RCC), mapped to 9p24.3 and encoded an ankyrin-repeat domain-containing protein. Its frequent deletion was found to be associated with several human malignant tumors, cerebral palsy, and neuronal and developmental diseases. However, its functional role in nasopharyngeal cancer (NPC) was still unknown. In the present study, we found that Kank1 expression was down-regulated in NPC cells than in human nasopharyngeal epithelial cell line NP69 and demethylating agent 5-aza-2'-deoxycytidine (5-aza-CdR) could improve its mRNA and protein expression level. Further studies demonstrated that DNA methylation might be the mainly cause for Kank1 decreased expression and restored Kank1 expression mediated by 5-aza-CdR played a key role in suppressing NPC cells growth and inducing its apoptosis. Our primary results revealed new function of Kank1 for NPC and implied that epigenetic regulation especially demethylation may have a potential value for NPC treatment.