MicroRNA-320a inhibits cell proliferation, migration and invasion by targeting BMI-1 in nasopharyngeal carcinoma

•Levels of miR-320a are frequently lower in NPC cell lines and tissues.•Overexpression of miR-320a suppresses NPC cell proliferation in vitro and in vivo.•Overexpression of miR-320a reduces migration and invasion of NPC cells.•miR-320a directly and functionally targets BMI-1.•BMI-1 is up-regulated in NPC specimens and inversely correlates with miR-320a levels. In the present study, we investigated the roles and molecular mechanisms of miR-320a in human nasopharyngeal carcinoma (NPC). miR-320a expression was strongly reduced in NPC tissues and cell lines. Overexpression of miR-320a significantly suppressed NPC cell growth, migration, invasion and tumor growth in a xenograft mouse model. A luciferase reporter assay revealed that miR-320a could directly bind to the 3′ UTR of BMI-1. Overexpression of BMI-1 rescued miR-320a-mediated biological function. BMI-1 expression was found to be up-regulated and inversely correlated with miR-320a expression in NPC. Collectively, our data indicate that miR-320a plays a tumor suppressor role in the development and progression of NPC and may be a novel therapeutic target against NPC.