HIF-2α promotes epithelial-mesenchymal transition through regulating Twist2 binding to the promoter of E-cadherin in pancreatic cancer

J Exp Clin Cancer Res. 2016 Feb 3:35:26. doi: 10.1186/s13046-016-0298-y.

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.

Method: 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.

Conclusion: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, CD
  • Basic Helix-Loop-Helix Transcription Factors / metabolism*
  • Cadherins / genetics*
  • Cell Line, Tumor
  • Cell Movement
  • Epithelial-Mesenchymal Transition*
  • Female
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Male
  • Neoplasm Invasiveness
  • Pancreatic Neoplasms / genetics
  • Pancreatic Neoplasms / metabolism
  • Pancreatic Neoplasms / pathology*
  • Promoter Regions, Genetic
  • Protein Binding
  • Repressor Proteins / metabolism*
  • Twist-Related Protein 1 / metabolism*

Substances

  • Antigens, CD
  • Basic Helix-Loop-Helix Transcription Factors
  • CDH1 protein, human
  • Cadherins
  • Repressor Proteins
  • TWIST2 protein, human
  • Twist-Related Protein 1
  • endothelial PAS domain-containing protein 1