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

Abstract

BackgroundEpithelial-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.MethodIn 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.ResultsWe 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.ConclusionThese 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.

HIF-3α Promotes Metastatic Phenotypes in Pancreatic Cancer by Transcriptional Regulation of the RhoC–ROCK1 Signaling Pathway

“…A correlation between hypoxia and pancreatic cancer has been recognized for a number of years (21), and a role for HIF-1a and HIF-2a in pancreatic cancer has previously been investigated (22,23). In this study, we showed that HIF-3a expression is stimulated to a greater extent than either HIF-1a or HIF-2a under hypoxic conditions in pancreatic cancer cells.…”

CDH1 (E-cadherin) expression independently affects clinical outcome in acute myeloid leukemia with normal cytogenetics

“…Epithelial-to-mesenchymal transition (EMT) is a process through which epithelial cells acquire motile and invasive properties and change into mesenchymal-like cells [8,9]. Naturally, EMT occurs in cell development, but during carcinogenesis, it can augment oncogenic transformation of cancer cells, making them prone to migration and invasion [8].…”

Pharmacologic ascorbate (P-AscH−) suppresses hypoxia-inducible Factor-1α (HIF-1α) in pancreatic adenocarcinoma

“…Unlike the other isoforms of HIF [7–9], clinically HIF-1α appears to be important in PDAC survival. Using immunohistochemical methods, Sun et al demonstrated that HIF-1α in PDAC specimens has a strong association with prognosis and correlates with expression of vascular endothelial growth factor (VEGF) [2].…”

“…The cellular response to hypoxia is primarily mediated by hypoxia-inducible transcription factors (HIF-1, 2, and 3), of which the HIF-1 isoform is well established to correlate with pancreatic cancer (PDAC) metastasis and prognosis [1–6] while the relationship with the other isoforms is inconclusive [7–9]. HIF-1 is active in its heterodimeric form, made up of HIF-1α and HIF-1β subunits.…”