Objective: We aimed at studying the role of the most deregulated miR-99a, identifying its downstream targets, and exploring the clinical potential of miR-99a and its target(s) in oral cancer.
Subjects and methods: Following confirmation of miR-99a deregulation in nine oral lines and 26 pairwise clinical specimens, miR-99a-manipulated oral cancer cells were subjected to cell proliferation, migration, invasion, and in vivo murine metastasis assays. We characterized putative miR-99a target(s) using luciferase reporter assays and genetic manipulation. The inverse relation of miR-99a and its target(s) was examined in clinical specimens using real-time PCR and Western blot analysis.
Results: MiR-99a down-regulation was confirmed both in tested oral cancer cell lines and clinical specimens. Ectopic miR-99a expression inhibited oral cancer cell migration and invasion. Anti-miR-99a, silencing miR-99a functions, had the opposite effect. Myotubularin-related protein 3 (MTMR3) with one evolutionarily conserved seed region in the 3'-untranslated region was a novel miR-99a target. Depleting MTMR3 expression significantly reduced cell proliferation, migration, or invasion. There was an inverse expression of miR-99a and MTMR3 protein in oral cancer lines and clinical specimens.
Conclusion: miR-99a repressed oral cancer cell migration and invasion partly through decreasing MTMR3 expression. MTMR3 may serve as a therapeutic target for oral cancer treatment.
Keywords: MTMR3; miR-99a; microRNA; oral cancer; phosphatase.
© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.