Papillary thyroid carcinoma (PTC) is a common malignant tumor of thyroid tissues that affects people's health. The occurrence of PTC has been found to be related with abnormal expression of microRNA (miR). MiR-200c is correlated with occurrence of multiple tumors but has not been studied in PTC. This study thus investigated the correlation between miR-200c and PTC, in order to provide the evidence of screening PTC tumor markers. Real-time PCR was used to detect miR-200c expression in PTC and

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... acent tissues, along with those in Nthy-ori3-1, TPC-2, and BCPAP cells. CCK8 assay was applied to detect the effect of miR-200c on BCPAP cell proliferation via its over-expression. Dual-luciferase reporter assay and Western blotting were used to elucidate the regulatory effect of miR-200c on X-linked inhibitor of apoptosis (XIAP). Expression level of miR-200c in PTC tissues was significantly lower than that in adjacent tissues (t=4.84, P<0.001). MiR-200c level in TPC-1 and BCPAP cells was obviously lower than that in Nthy-ori3-1 cells (P<0.05). MiR-200c transfection also decreased cell numbers (P<0.05). Luciferase intensity in miR-200c mimics + pmirGLO-XIAP-3'UTR-wt co-transfected cells was decreased by 60.92% compared with control group (P<0.05). XIAP protein expression was also suppressed by miR-200c mimics transfection. PTC pathogenesis might be related with miR-200c down-regulation. MiR-200c may inhibit PTC growth via down-regulating XIAP expression.