Expression And Function Of MiR-374 In Papillary Thyroid Carcinoma

Objective:To explore the differential expression of miRNAs in papillary thyroid carcinoma tissue and paracancerous tissue in thyroid papillary carcinoma,and to further analyze the role of differential expression of miRNA in the development of thyroid papillary carcinoma.Methods:From October 2010 to May 2015,56 thyroid papillary carcinoma tissues and paracancerous tissues of thyroid papillary carcinoma patients were diagnosed at the Second Hospital of Dalian Medical University.The differential expression of miRNA in papillary thyroid carcinoma and paracancerous tissue was screened by chip analysis.The most significant differentially expressed miR-374 was selected as the research object.Real-time PCR was used to detect the expression of miR-374 in 56 pairs of tissues collected.In the thyroid cancer cell line T686,miR-374 was overexpressed or silenced respectively.Then,the regulation of miR-374 on the proliferation and migration of T686 cells was detected by MTT and Transwell.MiRDB software was used to analyze the proteins that miR-374 could regulate,and the target binding sites of miR-374 and STAT3 were obtained.Luciferase reporter gene assay was used to detect the targeting effect of miR-374 on STAT3.The regulatory effect of miR-374 on STAT3 protein was detected by real-time PCR and Western blot.Results:The results of chip analysis showed that the 14 kinds of miRNAs were differentially expressed in papillary thyroid carcinoma and para cancerous tissue,and the most significant downregulation of miR-374 was in papillary thyroid carcinoma.In the 56 tissue specimens we collected,the expression of miR-374 in papillary thyroid carcinoma was reduced by about 55%(P<0.05)than in the para cancerous tissue.The MTT experiment found that the proliferation rate of miR-374 overexpressed T686 cells was significantly lower than that of normal miR-374 cells(P<0.05),and the proliferation rate of T686 cells with low miR-374 expression was higher than that of the control group(P<0.05).Tranwell experiments proved that miR-374 overexpression could migrate T686 cells all the time,and the migration ability of T686 cells was promoted after low expression of miR-374.Further,we demonstrated by luciferase reporter gene that miR-374 could inhibit STAT3 protein activity through direct targeting.Overexpression of MiR-374 can significantly reduce the expression of STAT3 and RNA.Conclusions:MiR-374 has a low expression in papillary thyroid carcinoma.MiR-374 can regulate the proliferation and migration of thyroid cancer cells to influence the occurrence and development of thyroid cancer.The regulatory effect of MiR-374 on the occurrence and development of papillary thyroid carcinoma may be achieved through its targeting effect on STAT3.MiR-374 may be a potential target for diagnosis and treatment of papillary thyroid carcinoma.