MicroRNA-365 inhibits growth, invasion and metastasis of malignant melanoma by targeting NRP1 expression.

Objective: The role of miR-365 in cancer cells seemed controversial in previous studies. We thereby in this article aimed to define the role of miR-365 in malignant melanoma (MM) pathogenesis.

Methods: We detected miR-365 expression in malignant melanoma cell lines and then investigated the effects of miR-365 on the metastasis and malignancy of melanoma cells. The correlation between miR-365 level and NRP1 (neuropilin1) was further investigated in clinical malignant melanoma specimens.

Results: MiR-365 was strongly down-regulated in malignant melanoma (MM) tissues and cell lines, and its expression levels were associated with lymph node metastasis and clinical stage, as well as overall survival and replase-free survival of MM. We also found that ectopic expression of miR-365 inhibited MM cell proliferation and MM metastasis in vitro and in vivo. We further identified a novel mechanism of miR-365 to suppress MM growth and metastasis. NRP1 was proved to be a direct target of miR-365, using luciferase assay and western blot. NRP1 over-expression in miR-365 expressing cells could rescue invasion and growth defects of miR-365. In addition, miR-365 expression inversely correlated with NRP1 protein levels in MM.

Conclusion: Our data suggest that miR-365 functions as a tumor suppressor in MM development and progression, and holds promise as a prognostic biomarker and potential therapeutic target for MM.