Expression of microRNA-22 in thyroid papillary carcinoma and its relationship with chemotherapy sensitivity

Objective To investigate the expression of microRNA (miRNA, miR) -22 (miR-22) in thyroid papillary carcinoma tissue, serum and cell lines, and its relationship with chemotherapy sensitivity. Methods The medical records, thyroid papillary carcinoma tissue and serum samples from 21 cases diagnosed thyroid papillary carcinoma were collected. Serum samples from 21 individuals undergoing the physical examination and 21 patients with thyroid nodules were also collected as controls. The expressions of miR-22 in carcinoma tissue, paracarcinoma tissue, serum, normal thyroid cell line and thyroid carcinoma cell line were detected by real-time fluorescent quantitative polymerase chain reaction (real-time qPCR) , and analyzed. Then the target genes and signaling pathways of miR-22 were predicted by bioinformatics software. Results The expression of miR-22 in carcinoma tissue was significantly lower than that in paracancerous tissue, while the expression in serum from thyroid papillary carcinoma patients was significantly higher than that from healthy people and thyroid nodules patients. MiR-22 expression level in carcinoma tissue was negatively correlated with that in carcinoma serum (r=-0.851, P<0.01) . MiR-22 relative expression in carcinoma tissue of T3-T4 stage (0.45±0.08) was significantly lower than that of T1-T2 stage (0.61±0.18) (t=-2.809, P<0.01) ; while the miR-22 relative expression in carcinoma tissue of N- stage (0.64±0.16) was significantly higher than that of N+ stage (0.48±0.10) (t=2.789, P<0.01) . The relative expression of miR-22 in carcinoma serum of T3-T4 stage (12.76±1.60) was significantly higher than that of T1-T2 stage (9.91±2.74) (t=2.806, P<0.01) . The relative expression of miR-22 in patients with high sensitivity to chemotherapy (0.71±0.14) was significantly higher than that in patients with low sensitivity to chemotherapy (0.42±0.13) (t=4.575, P<0.01) . The target genes of miR-22 were SIRT1 and HMGB1 predicted by bioinformatics software, and they took part in many signaling pathways, such as endocytosis, regulation of actin cytoskeleton, MAPK signaling pathway, pathways in cancer and so on. Conclusions The expression of miR-22 greatly reduces in carcinoma tissue and cell lines, and is associated with T, N stages and chemotherapy sensitivity. However, the expression increases in serum from thyroid papillary carcinoma patients. MiR-22 takes part in signal pathways and may affect the occurrence and development of thyroid papillary carcinoma through target regulating the expression of SIRT1 and HMGB1. Key words: MicroRNAs; Thyroid papillary carcinoma; Expression quantity; Chemotherapy sensitivity