MicroRNA-92b suppresses proliferation of papillary thyroid cancer cells by regulating ilent information regulator 1 gene expression

Objective To investigate the regulating effects of microRNA (miRNA, miR)-122 on the expression of ilent information regulator 1 (SIRT1), and the proliferation abilities of papillary thyroid cancer cells. Methods Real-time quantitative polymerase chain reaction (Real-time PCR) was used to observe the expression of miR-122 in papillary thyroid carcinoma and adjacent tissues and to analyze its correlation with SIRT1 expression. After transfecting miR-122 mimics into human papillary thyroid carcinoma cell line TPC-1, the dual luciferase reporter gene assay was used to observe the regulation of miR-122 on SIRT1 gene. The effect of miR-122 on the proliferation of thyroid cancer cells was observed by CCK-8 assay. At the same time, the overexpressed SIRT1 plasmid was co-transfected into TPC-1 cells, and then the effect of miR-122 and SIRT1 expression on the proliferation of papillary thyroid carcinoma cells was detected by CCK-8 assay. Analysis was performed using GraphPad Prism 7.0 statistical software. Correlation analysis was performed using Spearman rank correlation analysis. Student’s t test was used to compare the two sample means. Results Compared with adjacent tissues (1.20±0.15), the expression level of miR-122 (3.06±0.26) in papillary thyroid carcinoma was significantly down-regulated, and the difference was statistically significant (t=5.972, P<0.01). Correlation analysis showed that miR-122 was negatively correlated with SIRT1 mRNA expression (r=-0.621, P<0.01). The relative luciferase activity of SIRT1 in miR-122 mimics transfection group was significantly lower than that in the control group, and the difference was statistically significant (t=17.730, P<0.01). The cell proliferation ability of miR-122 mimics group was significantly lower than that of the control group, and the difference was statistically significant (t=3.991, P<0.01). After co-transfection of the SIRT1 overexpression plasmid, the inhibition of the proliferation of thyroid papillary carcinoma cells by miR-122 mimics was reversed. Conclusion miR-122 can inhibit the proliferation of papillary thyroid cancer cells, and its mechanism may be related to the targeted inhibition of SIRT1 expression. Key words: MicroRNA-122; Ilent information regulator 1; Papillary thyroid cancer; Proliferation