miR-542-3p suppresses invasion and metastasis by targeting the proto-oncogene serine/threonine protein kinase, PIM1, in melanoma

Aberrant microRNAs (miRNAs) contribute to metastasis of various cancer types, including melanoma. miR-542-3p has been characterized as a tumor suppressor in several cancers. However, the exact expression patterns of miR-542-3p and the precise molecular mechanisms underlying its role in melanoma require further exploration. In the current study, we demonstrated that miR-542-3p is significantly downregulated in melanoma cell lines and clinical specimens. Exogenous expression of miR-542-3p resulted in marked inhibition of melanoma cell migration, invasion and epithelial-mesenchymal transition (EMT) in vitro and lung metastasis in vivo. The proto-oncogene serine/threonine protein kinase, PIM1, was identified as a direct target of miR-542-3p using luciferase reporter assay, qRT-PCR and western blot analyses. Overexpression of PIM1 partially rescued miR-542-3p-mediated suppression of cell migration, invasion and EMT. Our results collectively indicate that miR-542-3p serves as a metastasis suppressor in melanoma, supporting its utility as a promising therapeutic candidate.