MicroRNA-15a-5p suppresses cancer proliferation and division in human hepatocellular carcinoma by targeting BDNF

Jianting Long, Chunlin Jiang, Baoxian Liu, Shi Fang, Ming Kuang

We examined the expression pattern and functional roles of microRNA 15a-5p (miR-15a-5p) in human hepatocellular carcinoma (HCC). Possible miR-15a-5p aberrant expression in HCC cell lines or clinical HCC specimens was examined by quantitative real-time PCR (qRT-PCR). In HCC HepG2 and SNU-182 cells, miR-15a-5p was ectopically overexpressed by lentiviral transduction. Its effect on HCC proliferation, cancer division, and in vivo tumor growth were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell cycle assay, and tumorigenicity assay, respectively. The targeting of miR-15a-5p on its downstream gene, brain-derived neurotrophic factor (BDNF), was examined by dual-luciferase assay, qRT-PCR, and Western blot, respectively. BDNF was then overexpressed in HepG2 and SNU-182 cells to evaluate its selective effect on miR-15a-5p in HCC modulation. MiR-15a-5p is aberrantly downregulated in in vitro HCC cell lines and in vivo HCC clinical specimens. Ectopic overexpression of miR-15a-5p suppressed cancer proliferation, induced cell cycle arrest in HepG2 or SNU-182 cells in vitro, and inhibited HCC tumor growth in vivo. MiR-15a-5p selectively and negatively regulated BDNF at both gene and protein levels in HCC cells. Forced overexpression of BDNF effectively reversed the tumor suppressive functions of miR-15a-5p on HCC proliferation and cell division in vitro. Our study demonstrated that miR-15a-5p is a tumor suppressor in HCC and its regulation is through BDNF in HCC.