MicroRNA-29a Inhibits Growth, Migration and Invasion of Melanoma A375 Cells in Vitro by Directly Targeting BMI1

Background/Aims: Melanoma is one of the most aggressive malignant tumors, with increasing incidence, poor prognosis, and lack of any effective targeted therapies. Abnormal expression of miR-29a has been found in several types of cancers, including melanoma. In this study, experiments were performed to investigate the role of miR-29a in melanoma, and the molecular mechanism by which miR-29a represses melanoma. Methods: miR-29 and Bmi1 expression was examined by quantitative real-time polymerase chain reaction (qRT-PCR). The cell viability, apoptosis, migration and invasion were respectively determined by Cell Counting Kit-8 assay, Propidium iodide (PI) fluorescein isothiocynate (FITC)-Annexin V staining assay, wound healing assay and transwell assay. Luciferase reporter assay was performed to determine a target gene of miR-29a. Western blot was used to analyze protein expression of apoptosis-related proteins, Bmi1, Wnt/β-catenin and Nuclear factor-κB (NF-κB) pathway target genes. Results: miR-29a was down-regulated in all tested melanoma cell lines. Up-regulation of miR-29a effectively inhibited cell viability, migration, and invasion, but promoted apoptosis in A375 cells. Bmi1 was a direct target gene of miR-29a. Transfection with miR-29a mimic decreased cell migration and invasion and Bmi1 expression in Malme-3M cells, SK-MEL-2, SK-MEL-5, and M14 cell lines. Moreover, miR-29a might suppress growth, migration and invasion of A375 cells by negatively regulating Bmi1. In addition, our results demonstrated that transfection with miR-29a mimic effectively blocked Wnt/β-catenin and NF-κB pathways via down-regulating Bmi1. Conclusion: miR-29a could be functioned as a potential tumor suppressor through direct regulation of Bmi1 in melanoma cells.