MicroRNA-501 promotes HBV replication by targeting HBXIP.

MicroRNAs (miRNAs) can negatively regulate gene expression and also induce or inhibit viral replication. In the present study, we found 10 miRNAs were differentially expressed in a stable HBV-producing cell line (HepG2.2.15) compared with its control cell line (HepG2) by miRNA array analysis. miR-501 was significantly up-regulated in HepG2 cells and tissues with high-HBV replication. miR-501 expression was significantly up-regulated in hepatocellular carcinoma tissues, where HBV replication kept high. Down-regulating miR-501 could significantly inhibit HBV replication, but not influence the growth of HepG2.2.15 cells. Luciferase reporter and western blot assays revealed that HBXIP, an inhibitor of HBV replication, was a potential target of miR-501. Moreover, knockdown of HBXIP rescued the inhibition of HBV that occurred after the loss of miR-501 in HepG2.2.15 cells, suggesting that miR-501 induced HBV replication partially by targeting HBXIP. Thus, knockdown of miR-501 might provide a new mechanism and therapeutic target for inhibiting HBV replication.