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 miR-181a 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.