['MicroRNA-206 (miR-206) has been proven to be downregulated in many human malignancies and is correlated with tumor progression. However, the roles of miR-206 and its related molecular mechanisms in oral squamous cell carcinoma (OSCC) are still unclear. Thus, the aim of this study was to explore the effects of miR-206 in OSCC tumorigenesis and development.', 'Quantitative real-time polymerase chain reaction was used to detect miR-206 expression in OSCC cell lines and primary tumor tissues. The association of miR-206 expression with clinicopathological factors and prognosis was also analyzed. In addition, the effects of miR-206 on the biological behavior of OSCC cells were investigated. Lastly, the potential regulatory function of miR-206 on K-Ras expression was confirmed.', 'MiR-206 expression was significantly downregulated in OSCC tissue samples and cell lines (both P<0.001). Decreased miR-206 expression was significantly associated with advanced tumor node metastasis (TNM) stage, advanced T classifications (ie, size and/or extent of the primary tumor), positive N classification (ie, spread to regional lymph nodes), and shorter overall survival. In addition, upregulation of miR-206 in Tca8113 cells was able to reduce cell proliferation, invasion, and migration and promote cell apoptosis in vitro. Further, K-Ras was confirmed as a direct target of miR-206 by using luciferase reporter assay.'] Does miR-206 functions as a tumor suppressor and directly target K-Ras in human oral squamous cell carcinoma?