Reflux conditions induce E-cadherin cleavage and EMT via APE1 redox function in oesophageal adenocarcinoma
Heng Lu, Long Cao, Farah Ballout, Abbes Belkhiri, Dunfa Peng, Lei Chen, Zheng Chen, Mohammed Soutto, Timothy C. Wang, Jianwen Que, Silvia Giordano, M. Kay Washington, Steven Chen, Oliver G. McDonald, Alexander Zaika, Wael El-Rifai
Abstract
Objective Chronic gastro-oesophageal reflux disease, where acidic bile salts (ABS) reflux into the oesophagus, is the leading risk factor for oesophageal adenocarcinoma (EAC). We investigated the role of ABS in promoting epithelial-mesenchymal transition (EMT) in EAC. Design RNA sequencing data and public databases were analysed for the EMT pathway enrichment and patients’ relapse-free survival. Cell models, pL2-IL1β transgenic mice, deidentified EAC patients’ derived xenografts (PDXs) and tissues were used to investigate EMT in EAC. Results Analysis of public databases and RNA-sequencing data demonstrated significant enrichment and activation of EMT signalling in EAC. ABS induced multiple characteristics of the EMT process, such as downregulation of E-cadherin, upregulation of vimentin and activation of ß-catenin signalling and EMT-transcription factors. These were associated with morphological changes and enhancement of cell migration and invasion capabilities. Mechanistically, ABS induced E-cadherin cleavage via an MMP14-dependent proteolytic cascade. Apurinic/apyrimidinic endonuclease (APE1), also known as redox factor 1, is an essential multifunctional protein. APE1 silencing, or its redox-specific inhibitor (E3330), downregulated MMP14 and abrogated the ABS-induced EMT. APE1 and MMP14 coexpression levels were inversely correlated with E-cadherin expression in human EAC tissues and the squamocolumnar junctions of the L2-IL1ß transgenic mouse model of EAC. EAC patients with APE1 high and EMT high signatures had worse relapse-free survival than those with low levels. In addition, treatment of PDXs with E3330 restrained EMT characteristics and suppressed tumour invasion. Conclusion Reflux conditions promote EMT via APE1 redox-dependent E-cadherin cleavage. APE1-redox function inhibitors can have a therapeutic role in EAC.