2034

EPAS1

BACKGROUND: Adenoid cystic carcinoma (ACC) of salivary gland is characterized by advanced local invasion and distant metastasis. Intratumoral hypoxia was reported to be associated with epithelial-mesenchymal transition (EMT) regulators. The purpose of this study was to evaluate the relationship between hypoxia-inducible factor (HIF)-2alpha, TWIST2, and SIP1 expression and the invasion and metastasis in ACC of salivary gland. METHOD: In vitro we first detected the expression of HIF-2alpha, TWIST2, and SIP1 in two ACC cell lines by Western blot and real-time RT-PCR. Then, in vivo, a retrospective investigation of 121 patients with ACC from Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University between 1996 and 2005 was carried out using immunohistochemistry to analyze the association between the expression of these three factors and clinical-pathological factors of patients. RESULTS: The protein and mRNA levels of HIF-2alpha, TWIST2, and SIP1 in the high-metastasis cell line (ACC-M) were much higher than those of the low-metastasis cell line (ACC-2). The positive expression of HIF-2alpha, TWIST2, and SIP1 (71.07%, 42.98%, and 38.02%, respectively) was associated with the perineural invasion, the local recurrence, and distant metastasis of patients with ACC (P < 0.05). The patients with the positive coexpression of the three factors had a lower survival rate than those with the negative expression (P < 0.05). CONCLUSION: It is proposed that the elevated expression of HIF-2alpha, TWIST2, and SIP1 can contribute to invasion and metastasis of ACC, and there might be some correlation between the hypoxia microenvironment and EMT in ACC.CI - (c) 2011 John Wiley & Sons A/S.

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-2alpha in EMT in pancreatic cancer. METHOD: In this study, we investigated the expression of HIF-2alpha 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-2alpha in pancreatic cancer cells to examine the role of HIF-2alpha on invasion and migration in vitro. Finally, we tested the relation of HIF-2alpha and EMT related proteins by Western blot and determined whether HIF-2alpha regulated EMT through Twist regulating the expression of E-cadherin by Chromatin immunoprecipitation (ChIP) assay. RESULTS: We found that HIF-2alpha 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-2alpha protein between two groups (chi2 = 45.549, P < 0.05). In addition, the staining for HIF-2alpha 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-2alpha 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-2alpha promotes EMT in pancreatic cancer by regulating Twist2 binding to the promoter of E-cadherin, which meant that HIF-2alpha and this pathway may be effective therapeutic targets for pancreatic cancer.

Purpose: A role of Dicer, which converts precursor miRNAs to mature miRNAs, in the tumor-promoting effect of hypoxia is currently emerging in some tumor entities. Its role in hepatocellular carcinoma (HCC) is unknown.Experimental Design: HepG2 and Huh-7 cells were stably transfected with an inducible Dicer expression vector and were exposed to hypoxia/normoxia. HepG2-Dicer xenografts were established in nude mice; hypoxic areas and Dicer were detected in HCC xenografts and HCCs from mice with endogenous hepatocarcinogenesis; and epithelial-mesenchymal transition (EMT) markers were analyzed by immunohistochemistry or by immunoblotting. The correlation between Dicer and carbonic anhydrase 9 (CA9), a marker of hypoxia, was investigated in resected human HCCs.Results: Hypoxia increased EMT markers in vitro and in vivo and led to a downregulation of Dicer in HCC cells. The levels of Dicer were downregulated in hypoxic tumor regions in mice with endogenous hepatocarcinogenesis and in HepG2 xenografts. In human HCCs, the levels of Dicer correlated inversely with those of CA9, indicating that the negative regulation of Dicer by hypoxia also applies to HCC patients. Forced expression of Dicer prevented the hypoxia-induced increase in hypoxia-inducible factor 1alpha (HIF1alpha), HIF2alpha, hypoxia-inducible genes (CA9, glucose transporter 1), EMT markers, and cell migration.Conclusions: We here identify downmodulation of Dicer as novel essential process in hypoxia-induced EMT in HCC and demonstrate that induced expression of Dicer counteracted hypoxia-induced EMT. Thus, targeting hypoxia-induced downmodulation of Dicer is a promising novel strategy to reduce HCC progression. Clin cancer Res; 23(14); 3896-905. (c)2017 AACR.CI - (c)2017 American Association for cancer Research.

The aim of this study was to investigate the role of NEAT1 in hepatocellular carcinoma (HCC), and probe whether NEAT1 participate in the epithelial-mesenchymal transition (EMT) and metastasis regulated by HIF-2alpha. expression of lncRNA NEAT1 was initially assessed in HCC tissues and in a series of HCC cell lines. The correlations between NEAT1 levels and HIF-2alpha were analyzed through plasmid vector construction. The potential underlying mechanisms of NEAT1 in HCC were performed through in vitro and in vivo functional assays. expression of NEAT1, HIF-2alpha were significantly increased in HCC tissues and cell lines. Then, in vitro assays revealed that NEAT1 promotes EMT and metastasis by stimulating the inactivation of HIF-2alpha in HCC. An in vivo animal model also demonstrated the cancer promotion mechanism of NEAT1. In this study, we found that the NEAT1 was high expression in HCC. NEAT1 promotes tumor cell EMT, migration and invasion capacities by stimulating the activation of HIF-2alpha in HCC.CI - (c) 2017 Wiley Periodicals, Inc.