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. Oral Diseases (2014) 20, e65-e75

Early dissemination is a unique characteristic and a detrimental process of pancreatic ductal adenocarcinoma (PDAC); however, the underlying mechanism remains largely unknown. Here, we investigate the role of dual-specificity phosphatase-2 (DUSP2)-vascular endothelial growth factor-C (VEGF-C) axis in mediating PDAC lymphangiogenesis and lymphovascular invasion. Expression of DUSP2 is greatly suppressed in PDAC, which results in increased aberrant expression of extracellular vesicle (EV)-associated VEGF-C secretion. EV-VEGF-C exerts paracrine effects on lymphatic endothelial cells and autocrine effects on cancer cells, resulting in the lymphovascular invasion of cancer cells. Tissue-specific knockout of Dusp2 in mouse pancreas recapitulates PDAC phenotype and lymphovascular invasion. Mechanistically, loss-of-DUSP2 enhances proprotein convertase activity and vesicle trafficking to promote the release of the mature form of EV-VEGF-C. Collectively, these findings represent a conceptual advance in understanding pancreatic cancer lymphovascular invasion and suggest that loss-of-DUSP2-mediated VEGF-C processing may play important roles in early dissemination of pancreatic cancer.