MiR-181a promotes growth of thyroid cancer cells by targeting tumor suppressor RB1

OBJECTIVE: MicroRNAs (miRs) are critical regulators in cancer development and progression. The current study aimed to investigate the expression and potential function of miR-181a in thyroid cancer. PATIENTS AND METHODS: A total of 15 paired thyroid cancer tissues and adjacent normal tissues were subjected to Real-time Polymerase Chain Reaction (PCR) to evaluate miR181a expression. 3-(4,5 -dimethyl-2-thiazolyl) -2,5 -diphenyl-2-H-tetrazolium bromide (MTT) assay, enzyme linked immunosorbent assay (ELISA) or flow cytometry was employed to assess the growth activity, apoptosis and cell cycle, respectively, upon modulation of the miR-181a expression in TPC-1 cells. Western blot was used to assess protein expression. The interaction between miR-181a and RB1 was tested by luciferase activity assay. RESULTS: The expression of miR-181a was significantly upregulated in thyroid cancer tissues compared with the adjacent tissues. Inhibition of miR-181a attenuated cell growth, which could be abrogated by miR-181a co-transfection. MiR-181a overexpression reduced apoptosis and promoted cell cycle progression; inhibition of miR-181a exerted opposite effects on both cell cycle and apoptosis. MiR-181a directly suppressed RB1 expression. RB1 expression in tumor tissues was downregulated and negatively correlated with miR-181a expression. CONCLUSIONS: miR-181a plays an oncogenic role in thyroid cancer; by targeting RB1, it promotes cell cycle progression and inhibits apoptosis.