Abstract:

To investigate the expressions of Stat3 and Stat5  in differentiated thyroid carcinoma(DTC) tissues  and their relationships with clininopathological factors,and study the roles of Stat3 and Stat5 in the occurrence and development of DTC.Methods The expressions of Stat3,Stat5,P53,P21 in  42  patients with DTC  including 38 papillary thyroid carcinoma(PTC) and 4 follicular thyroid carcinoma(FTC),30 cases of thyroid adenomas（TA） and 15 normal thyroid tissues (NTT) adjacent to adenomas   were detected by immunohistochemical (SABC) staining method.The positive expression rates in different tissues were compared,and their corelations with clinicopathological factors of DTC   were analyzed.Results The positive expression rates of Stat3 and Stat5 in DTC were significantly increased compared with TA and NTT respectively (P<0.05),their expression rates were closely correlated with pathological typing of DTC(r=0.76，P<0.05;r=0.80，P<0.05);the expression rates of Stats and Stat5 in PTC were lower than those in FTC(P<0.05).The expression rate of Stat5 was significantly higher than that of Stat3 and they had positive correlation(r=0.78，P<0.05).The positive expression rate of P53 in DTC tissue （30.9%） was higher than those in TA(0%) and NTT(0%)(P<0.05).The positive expression rate of P21 protein in DTC tissue was significantly decreased. The expression rates of  Stat3（ 54.8%） and Stat5 （66.7%）were significantly higher than that of P53(30.9%)and there were positive correlations  with  P53 (r=0.77,P<0.05；r=0.72,P<0.05)and negative correlation with  P21（r=－0.87,P<0.05；r=－0.67,P<0.05）.Conclusion The  abnormal expressions of Stat3 and Stat5 may play  important roles in the carcinogenesis of thyroid carcinoma.Perhaps the abnormal expressions of Stat3 and Stat5 may be caused by mutation of p53 and deactivation of p21.The abnormal increase of the expression rates of  Stat5 and Stat3   may lead to the occurrence and development of DTC.

Key words: signal transducer and activator of transcription;P53;P21;thyroid neoplasms;gene expression