title: HIF-2α promotes epithelial-mesenchymal transition through regulating Twist2 binding to the promoter of E-cadherin in pancreatic cancer.
abstract: BACKGROUND
  Epithelial-mesenchymal transition (EMT) is a dedifferentiation process that mainly involves in mesenchymal marker upregulation, epithelial maker downregulation and cell polarity loss. Related hypoxia factors play a crucial role in EMT, however, it remains few evidence to clarify the role of HIF-2α in EMT in pancreatic cancer.
  
  
  METHODS
  In this study, we investigated the expression of HIF-2α and E-cadherin by immunohistochemistry in 70 pancreatic cancer patients, as well as the correlation to the clinicopathologic characteristics. Then we regulated the expression of HIF-2α in pancreatic cancer cells to examine the role of HIF-2α on invasion and migration in vitro. Finally, we tested the relation of HIF-2α and EMT related proteins by Western blot and determined whether HIF-2α regulated EMT through Twist regulating the expression of E-cadherin by Chromatin immunoprecipitation (ChIP) assay.
  
  
  RESULTS
  We found that HIF-2α protein was expressed positively in 67.1% (47/70) of pancreatic cancer tissues and 11.4% (8/70) of adjacent non-tumor pancreatic tissues, and there was a significant difference in the positive rate of HIF-2α protein between two groups (χ2 = 45.549, P < 0.05). In addition, the staining for HIF-2α was correlated with tumor differentiation (P < 0.05), clinical stage (P < 0.05) and lymph node metastasis (P < 0.05), while E-cadherin expression was only correlated with lymph node metastasis (P < 0.05). HIF-2α promoted cell migration, invasion in vitro, and regulated the expression of E-cadherin and MMPs, which are critical to EMT. Our further ChIP assay suggested that only Twist2 could bind to the promoter of E-cadherin in -714 bp region site, but there is no positive binding capacity in -295 bp promoter region site of E-cadherin. Clinical tissues IHC staining showed that Twist2 and E-cadherin expression had an obviously negative correlation in pancreatic cancer. Nevertheless, it had no obvious correlation between Twist1 and E-cadherin.
  
  
  CONCLUSIONS
  These findings indicated that HIF-2α promotes EMT in pancreatic cancer by regulating Twist2 binding to the promoter of E-cadherin, which meant that HIF-2α and this pathway may be effective therapeutic targets for pancreatic cancer.
authors: Department of General Surgery, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China. 20135232100@stu.suda.edu.cn.
authors: Jian
authors: J
authors: Yang
authors: Department of General Surgery, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China. 852576430@qq.com.
authors: Xu
authors: X
authors: Zhang
authors: Department of General Surgery, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China. yangjian38850@163.com.
authors: Yi
authors: Y
authors: Zhang
authors: Department of General Surgery, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China. zj0612@163.com.
authors: Dongming
authors: D
authors: Zhu
authors: Department of General Surgery, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China. yangjian88lucky@163.com.
authors: Lifeng
authors: L
authors: Zhang
authors: Department of General Surgery, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China. suzhouyiuan@gmail.com.
authors: Ye
authors: Y
authors: Li
authors: Department of Oncology, The First Affiliated Hospital of Soochow University, Suzhou, 215006, China. qbb24@126.com.
authors: Yanbo
authors: Y
authors: Zhu
authors: Department of General Surgery, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China. dechunlisuzhou@gmail.com.
authors: Dechun
authors: D
authors: Li
authors: Department of General Surgery, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China. zhoujian06@suda.edu.cn.
authors: Jian
authors: J
authors: Zhou
mesh_terms: D015703:Antigens, CD; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D015820:Cadherins / Q000235:genetics*; D045744:Cell Line, Tumor; D002465:Cell Movement; D058750:Epithelial-Mesenchymal Transition; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D009361:Neoplasm Invasiveness; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*; D051879:Twist-Related Protein 1 / Q000378:metabolism*; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D015703:Antigens, CD; D051792:Basic Helix-Loop-Helix Proteins; D015820:Cadherins; D012097:Repressor Proteins; D051879:Twist-Related Protein 1; D000099162:Endothelial PAS Domain-Containing Protein 1; C513384:CDH1 protein, human; C486274:TWIST2 protein, human