ABSTRACT
MicroRNAs (miRNAs) play important roles in melanoma. Although miR-637 has been suggested to be a tumor suppressor in several cancers, its function in melanoma and the molecular mechanism behind that function remain unclear. In this study, we investigated the role of miR-637 in human melanoma and explored its relevant mechanisms. We found that the expression of miR-637 is significantly downregulated in melanoma tissues and cell lines. While overexpression of miR-637 inhibited melanoma cell proliferation and cell cycle G1-S transition, and induced apoptosis. Inhibition of miR-637 promoted cell proliferation and G1-S transition, and suppressed apoptosis. Subsequent investigation revealed that miR-637 expression was inversely correlated with P-REX2a expression in melanoma tissues. P-REX2a was determined to be a direct target of miR-637 by using a luciferase reporter assay. Overexpression of miR-637 decreased P-REX2a expression at both the mRNA and protein levels, and suppression of miR-637 increased P-REX2a expression. Importantly, silencing P-REX2a recapitulated the cellular and molecular effects seen upon miR-637 overexpression, whereas, overexpression of P-REX2a eliminated the effects of miR-637 overexpression on melanoma cells. Furthermore, both enforced expression of miR-637 or silencing of P-REX2a resulted in activation of PTEN, leading to a decline in AKT phosphorylation. Taken together, our study demonstrates that miR-637 inhibites melanoma cell proliferation by activation of AKT signaling pathway and induces apoptosis through regulation of Bcl-2/Bax expression via targeting P-REX2a. These findings suggest that miR-637 plays a crucial role in melanoma progression, and may serve as a potential novel target for melanoma therapy.
