Enhanced Expression Of Twist1 And Its Acetylation And SIRT1 Is Associated With Lymph Nodes Metastasis In Papillary Thyroid Cancer

Objective: Papillary thyroid cancer(PTC)is the most common pathological type of thyroid cancer and its incidence is increasing year by year.Despite the favorable prognosis of PTC,the therapy of some highly aggressive PTC and PTC with lymph node metastasis(LNM)is still of challenges.Epithelial-to-mesenchymal transition(EMT)is a biological process in which non-motile,polarized epithelial cells undergo a series of biochemical alterations,becoming motile non-polarized mesenchymal cells with invasive capacity,resistance to apoptosis and altered biosynthesis of extracellular matrix components.EMT is related to the occurrence and development in a variety of malignant tumors,which is not only involved in the formation of cancer and angiogenesis,but also plays an important role in the process of cancer invasion and metastasis.Twist1 is a classical transcription factor that regulates EMT and can be modified by a variety of epigenetic approaches.SIRT1,as a classic sirtuin,appears to play a dual role in the development of tumors.The aim of this study was to explore the changes of EMT during the development and progression of PTC;the expression of Twis1 and SIRT1;the degree of acetylation of Twist1;and the interaction between Twist1 and SIRT1,to provide new ideas for studying the pathogenesis of PTC and a new target for obtaining more significant prognosis for PTC patients.Methods: The experiment was divided into three groups: normal group(Nor group),PTC group(P group)and PTC group with LNM(PL group).40 cases of normal thyroid tissue(i.e.,relatively normal thyroid tissue adjacent to nodular goiter),40 cases of PTC tissues and 40 cases of PTC tissues with LNM,which came from patients undergoing thyroid surgery at the Department of Vascular Surgery / Thyroid Surgery,the First Affiliated Hospital of China Medical University,from September 2016 to March 2017,were included in three groups,respectively.Combined with preoperative thyroid ultrasound and postoperative routine pathological reports,pathological diagnosis of the sample was confirmed by HE staining.The m RNA expression of E-Cadherin,Vimentin,Twist1 and SIRT1 was detected by Real-time PCR.The protein expression of E-Cadherin,Vimentin,Twist1 and SIRT1 was detected by Western Blot.The single labeling immunofluorescence was used for detecting protein expression of E-Cadherin,Vimentin,Twist1 and SIRT1 and for detecting subcellular localization of Twist1 and SIRT1.The double labeling immunofluorescence was used to detect the coexpression of Twist1 and SIRT1.The immunoprecipitation(Immunoprecipitation,IP)was applied for the detection of the degree of acetylation of Twist1;the application of Co-immunoprecipitation(COIP)was used to detect the interaction between Twist1 and SIRT1.Results: The expression of E-Cadherin was decreased gradually,and the expressions of Vimentin,Twist1 and SIRT1 were increased gradually among Nor group,P group and PL group,and the differences between the three groups were statistically significant.The degree of acetylation of Twist1 increased gradually among the three groups,with significant differences among the three groups.There was interaction between Twist1 and SIRT1 in the nucleus.Conclusions: During the development and progression of PTC,the EMT process is gradually strengthened.There is an interaction between Twist1 and Sirt1.The high expression of Twist1 and its acetylation and SIRT1 is associated with LNM.