MiR-9-5p Inhibits the Proliferation, Migration and Invasion of Choroidal Melanoma by Targeting BRAF

OBJECTIVE: According to different reports, miR-9-5p either facilitates or suppresses the occurrence of tumors. BRAF is a serine/threonine kinase involved in the MAPK pathway and is a proto-oncogene promoting the progression of many tumors, especially melanoma. The present study aimed to reveal the mechanism of action of miR-9-5p and BRAF in choroidal melanoma (CM). METHODS: RT-qPCR was used to detect the expression of miR-9-5p in CM cells after transfection with miR-9-5p mimics and inhibitor. EdU assay and Transwell assay, respectively, showed the proliferation, migration and invasion of CM cells after transfection with miR-9-5p mimics and inhibitor. A bioinformatics website was used for target prediction and the dual luciferase reporter assay was used to verify the interaction between miR-9-5p and BRAF. RT-qPCR and Western blot were performed to examine the expression of BRAF mRNA and protein, respectively. The BRAF protein was knocked down by siRNAs and then examined by Western blot. The effects of BRAF in CM cells were investigated by EdU assay and Transwell assay. Overexpressing BRAF and transfecting miR-9-5p mimics into choroidal melanoma cells confirmed the interaction between miR-9-5p and BRAF. RESULTS: miR-9-5p could bind to the BRAF mRNA 3’UTR and inhibit the transcription and translation of BRAF, thereby suppressing the proliferation, migration and invasion of CM cell lines. Moreover, silencing BRAF inhibited the progression of CM cells. CONCLUSIONS: In conclusion, this study is the first to investigate the association among BRAF, miR-9-5p and the progression of CM cells. In addition, the interaction between BRAF and miR-9-5p was explored for the first time in CM. Thus, our study suggests that miR-9-5p, BRAF and their interaction may act as potential therapeutic targets for CM.