Expression Of Mir-34a And Its Role In Human Papillary Thyroid Carcinoma

Objective: To investigate the biological function of microRNA-34a (miR-34a) in human papillary thyroid carcinoma (PTC). Methods: 89 pairs of human PTC and adjacent normal tissue were obtained. Real-time PCR were used to determine the level of miR-34a. Correlation of miR-34a with development of PTC was also analyzed. BCPAP and TPC1 cells were transfected with miR-34a mimics and scrambled miRNA was set as negative control. The effects of miR-34a on cell proliferation and cell cycle were evaluated by CCK8 and flow cytometry, respectively. Results: The relative expression level of miR-34a was significantly higher in PTC tissues than that in corresponding adjacent non-tumorous thyroid tissues; however, we found that relative lower expression level of miR-34a was observed in PTC with unfavorable features, including large tumor size, multi-focal distribution, lymph metastasis and high TNM stages. CCK8 assay showed that cell proliferation was inhibited after transfection of miR-34mimics. MiR-34a could block cell cycle trasition from G0/G1 phase into S phase in TPC1 cells. Conclusion: MiR-34a was up-regulated in PTC, and relative lower level of miR-34a was related to unfavorable features of PTC. It inhibits proliferation of PTC cells and block cell cycle transition from G0/G1 phase to S phase. MiR-34a acts as a tumor suppressor gene in PTC.