Bromodomain-containing protein 4 silencing by microRNA-765 produces anti-ovarian cancer cell activity

Bromodomain-containing protein 4 (BRD4) overexpression promotes ovarian cancer progression, and represents an important therapeutic oncotarget. This current study identified microRNA-765 (miR-765) as a novel BRD4-targeting miRNA. We showed that miR-765 directly associated with and silenced BRD4. In primary ovarian cancer cells and established cell lines (SKOV3 and CaOV3), ectopic overexpression of miR-765 inhibited cancer cell proliferation, migration and invasion, and induced apoptosis activation. In contrast, miR-765 inhibition by its anti-sense induced BRD4 upregulation to promote ovarian cancer cell proliferation, migration and invasion. Significantly, miR-765 overexpression-induced anti-ovarian cancer cell activity was largely attenuated by restoring BRD4 expression through an UTR-null BRD4 construct. Moreover, CRISPR/Cas9-induced BRD4 knockout (KO)inhibited proliferation and activated apoptosis in ovarian cancer cells. BRD4 KO in ovarian cancer cells abolished the functional impact of miR-765. miR-765 expression levels were downregulated in human ovarian cancer tissues and cells, correlating with the upregulation of BRD4 mRNA. Collectively, BRD4 silencing by miR-765produces significant anti-ovarian cancer cell activity. miR-765 could be further tested for its anti-ovarian cancer potential.