Upregulation of miR-519d-3p Inhibits Viability, Proliferation, and G1/S Cell Cycle Transition of Oral Squamous Cell Carcinoma Cells Through Targeting CCND1.

Background: MicroRNA (miR)-519d-3p suppresses tumor development, however, its role in oral squamous cell carcinoma (OSCC) has yet to be determined. Materials and Methods: OSCC and adjacent tissues were collected (n = 45 for adjacent; n = 21 for Stage I-II OSCC; n = 24 for Stage III-IV OSCC). The cell viability, proliferation, and cell cycle of OSCC were, respectively, assessed by the Cell Counting Kit-8 (CCK-8), colony formation assay, and flow cytometry. Relative expressions of cell cycle-regulated proteins (Cyclin D1 [CCND1], CDK4, and CDK6) and miR-519d-3p were measured with Western blot and quantitative real-time polymerase chain reaction as needed. Dual-luciferase reporter assay was performed to verify the prediction of TargetScan that miR-519d-3p and CCND1 shared potential binding sites. Correlation analysis between miR-519d-3p and CCND1 was performed with Pearson's correlation test. Results: In OSCC tissues, downregulating miR-519d-3p expression correlated with a higher tumor grade. Upregulating miR-519d-3p expression inhibited OSCC cell viability and proliferation, increased cells in G0/G1 phase and reduced those in S/G2 phase, and downregulated the expressions of cell cycle-related protein (CDK4, CDK6). CCND1 was the target gene of miR-519d-3p, and overexpressed CCND1 reversed the effects of upregulation of miR-519d-3p on suppressing the viability, proliferation, and cell cycle of OSCC cells. Conclusions: miR-519d-3p upregulation suppressed the cell viability, proliferation, and G1/S cell cycle transition of OSCC through targeting CCND1. The current findings provide a possible clinical option for OSCC treatment.