MiR-135b is a novel oncogenic factor in cutaneous melanoma by targeting LATS2.

Melanoma develops from pigment-producing melanocytes in the epidermis, and is the most common type of skin cancer. Because of the lack of effective therapies, the median survival of patients developing metastatic melanoma is less the 1 year. In this paper, we studied the oncogenic role of miR-135b in melanoma cells. We compared the miR-135b levels in 20 melanoma tissues in reference to their corresponding nontumor regions. Next, we studied the impact of miR-135b or its inhibitor on cell proliferation, migration, or apoptosis in either primary melanocytes or the melanoma cell line, respectively. Finally, we validated large tumor suppressor kinase 2 (LATS2) as the downstream target of miR-135b in a luciferase reporter assay, western blotting analysis, and knockdown study in primary melanocytes. MiR-135b expression was significantly upregulated in melanoma tissue. Overexpressing miR-135b in primary melanocytes promoted cell proliferation and migration. In contrast, inhibition of miR-135b expression suppressed the growth and metastasis of A-375 cells and enhanced cell apoptosis. LATS2 was confirmed as the target of miR-135b. Knockdown of LATS2 in melanocytes also promoted cell growth, but not cell invasion potential. Our findings showed miR-135b as a novel oncogene in melanoma tumorigenesis. The oncogenic mechanism may involve the downregulation of LATS2.