miR-33a is downregulated in melanoma cells and modulates cell proliferation by targeting PCTAIRE1.

MicroRNA-33a (miR-33a) was previously identified as a lipid regulator that controls the cellular balance between cholesterol and fatty acid metabolism. However, its role in tumor progression is largely unknown. The present study identified that miR-33a acts as a tumor suppressor in melanoma cells. The present study revealed that miR-33a was downregulated in melanoma cells compared with melanocytes. Overexpression of miR-33a suppressed the colony formation of human melanoma SK-MEL-1 and WM-115 cells. Furthermore, a bromodeoxyuridine incorporation assay and anaphase analysis revealed that miR-33a inhibits melanoma cell proliferation. miR-33a overexpression inhibited p27 phosphorylation and upregulated p27 expression. Additionally, the present study demonstrated that PCTAIRE1 was a direct target of miR-33a; miR-33a overexpression suppressed the luciferase activity of a reporter construct containing a 3'-untranslated region of PCTAIRE1 and downregulated PCTAIRE1 in melanoma cells. An overexpression of PCTAIRE1 reversed the miR-33a-induced p27 accumulation and tumor suppressive effects. In summary, the present findings offer novel mechanistic insights into miR-33a and its downstream target in melanoma cells.