Long Noncoding RNA H19 Promotes Tumorigenesis of Multiple Myeloma by Activating BRD4 Signaling by Targeting MicroRNA 152-3p

Multiple myeloma (MM) accounts for over twenty percent of hematological cancer-related death worldwide. Long noncoding RNA (lncRNA) H19 is associated with multiple tumorigenesis and is increased in MM, but the underlying mechanism of H19 in MM is unclear. In this study, the expression of H19, microRNA 152-3p (miR-152-3p), and BRD4 in MM patients was evaluated by quantitative real-time PCR (qRT-PCR) and Western blotting. Colony formation and flow cytometry analysis were used to determine the effects of H19 and miR-152-3p on MM cell proliferation, apoptosis, and cell cycle. A luciferase reporter assay was conducted to confirm the interaction among H19, miR-152-3p, and BRD4. A nude mouse xenograft model was established, and the cell proliferation and apoptosis were evaluated by immunohistochemistry (IHC) staining and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling assay. We found that levels of H19 and BRD4 were upregulated and the expression of miR-152-3p was downregulated in MM patients. Dual luciferase reporter assay showed H19 targeted miR-152-3p to promote BRD4 expression. Knockdown of H19 repressed proliferation and enhanced apoptosis and cell cycle G(1) arrest by upregulating miR-152-3p in MM cells. Furthermore, H19 knockdown suppressed the growth of xenograft tumor, reduced Ki-67 and BRD4 levels, and increased cell apoptosis in xenograft tumor tissues. Taking these results together, H19 knockdown suppresses MM tumorigenesis via inhibiting BRD4-mediated cell proliferation through targeting miR-152-3p, implying that H19 is a promising biomarker and drug target for MM.