miR-222 regulates the cell biological behavior of oral squamous cell carcinoma by targeting PUMA.

Previous reports have shown that low expression of p53 upregulated modulator of apoptosis (PUMA) and abnormal expression patterns of a number of miRNAs may be associated with poor prognosis in various types of human malignancies. As a member of the oncomiRs, miR-222 has been found to be upregulated in oral squamous cell carcinoma (OSCC). We hypothesized that there was an important relationship between miR-222 and PUMA in OSCC based on the prediction of the target genes of miR-222. In the present study, Pre-miR-222, As-miR-222 and the empty vector, were used to treat OSCC cells, respectively. Using the non-transfected cells as blank control, the expression levels of miR-222 and the PUMA gene were evaluated by RT-PCR and western blotting. Cell proliferation and migration abilities were analyzed by MTT and Transwell assays. Cell cycle distribution and apoptosis were assessed by flow cytometry. Our results demonstrated that, when compared with the blank control group, OSCC cells in the Pre-miR-222 transfection group showed increased expression of miR-222 and decreased expression of PUMA, enhanced proliferation and invasion abilities, and decreased apoptosis. In contrast, the above indices in the As-miR-222 transfection group confirmed the opposite results when compared with those in the Pre-miR-222 transfection group. In addition, no significant differences between the empty vector transfection group and the control group were noted. Our results suggest that miR-222 targets the expression of PUMA in OSCC cells and affects cell growth, invasive and apoptotic abilities. Thus, PUMA may be a possible new target for the treatment of OSCC.