MiR-214 promotes proliferation and inhibits apoptosis of oral cancer cells through MAPK/ERK signaling pathway

OBJECTIVE: To study the influences of micro ribonucleic acid (miR)-214 on the proliferation and apoptosis of oral cancer cells through the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway. MATERIALS AND METHODS: In this work, human oral cancer HB cell lines were cultured in vitro and then treated with phosphate-buffered saline (PBS) as Control group, with miR-214 mimics as miR-214 mimics group or with miR-214 mimics + ERK inhibitor U0126 as miR-214 mimics + U0126 group. The messenger RNA (mRNA) levels of miR-214 and ERK were determined using quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR), and the protein expression levels of phosphorylated ERK (p-ERK), ERK, proliferating cell nuclear antigen (PCNA), p21, and tubulin were measured via Western blotting (WB). Besides, the proliferation and apoptosis of cells in each group were evaluated via methyl thiazolyl tetrazolium (MTT) assay and Hoechst staining, respectively. RESULTS: Compared with Control group, miR214 mimics group exhibited increased expression of miR-214 in oral cancer cells (p<0.01), extremely raised expression levels of p-ERK and PCNA, but an extremely decreased protein expression level of p21 (p<0.01), whereas miR-214 mimics + U0126 group had remarkably lower levels of p-ERK and PCNA, and a considerably higher protein level of p21 than miR-214 mimics group (p<0.05). The qRT-PCR results showed no significant differences in the mRNA level of ERK among the three groups (p>0.05). In addition, the proliferation ability was enhanced successively in Control group, miR-214 mimics + U0126 group and miR-214 mimics group, and the increase was more notable in miR-214 mimics group, with statistically significant differences (p<0.05). Finally, it was found through the Hoechst apoptosis assay that compared with that in Control group, the cell apoptosis was notably inhibited in miR-214 mimics group, and it was greatly increased in miR-214 mimics + U0126 group. CONCLUSIONS: MiR-214 increases p-ERK level and p-ERK/ERK to activate the MAPK/ERK signaling pathway, raise PCNA level, and decrease p21 level, thereby promoting cell proliferation and inhibiting cell apoptosis.