Abstract 3269: APE1/NF-κB/PRDX2 activated by reflux conditions mediates chemoresistance in esophageal adenocarcinoma by suppressing ferroptosis
Authors: Chen Lei , Lu Heng , Ballout Farah , Peng Dunfa , Chen Zheng , Que Jianwen , Chen Steven , McDonald Oliver , Zaika Alexander , El-Rifai Wael 
Published: March 2024

Abstract
Background: Esophageal adenocarcinoma (EAC) stands out as one of the most lethal malignancies, characterized by a discouragingly low 5-year survival rate of less than 20%. Accumulating lines of evidence indicate that ferroptosis, a novel type of cell death, can regulate drug resistance. Peroxiredoxin 2 (PRDX2), an antioxidant enzyme, plays an antioxidant protective role in the cells under stress by regulating redox homeostasis. We aimed to elucidate the role of PRDX2 in regulating reactive oxygen species (ROS), ferroptosis, and chemoresistance in EAC.
Methods: In this investigation, we analyzed RNA sequencing data and public databases to uncover the aberrant overexpression and potential chemoresistance function of PRDX2 in EAC. We employed transient acidic bile salts exposure (ABS) and repeated ABS exposure (rABS) to mimic gastroesophageal reflux disease, the main risk factor for EAC, in in vitro cell models. EAC cells and 3D organotypic culture (OTC) served as platforms to delve into the anti-ferroptosis function and regulatory mechanisms of PRDX2. The findings were validated using patient-derived xenografts (PDX) and human EAC tissue microarrays (TMA).
Results: Elevated PRDX2 level was observed in both EAC patients and cell lines exhibiting poor responsiveness to chemotherapy. Intrinsic overexpression of PRDX2 emerged as a crucial factor in the recovery from ABS-exposure-induced lipid peroxidation. Silencing PRDX2 heightened the sensitivity of EAC cells to Oxaliplatin by inhibiting ferroptosis in a GPX4-dependent manner. Mechanistically, we found ABS activate the APE1/redox/NF-kB signal axis, leading to the upregulation of PRDX2 transcription. The co-overexpression of APE1 and PRDX2 was identified through both immunofluorescent staining in cells/OTC and immunohistochemistry staining in TMA. Moreover, the APE1-redox-specific inhibitor, APX2009, significantly sensitized EAC cells to Oxaliplatin by repressing PRDX2 and inducing ferroptosis. Remarkably, the combination therapy of Oxaliplatin and APX2009 achieved a synergistic effect in EAC-PDX tumors.
Conclusion: The study unveils a novel signaling axis, APE1/NF-kB/PRDX2, linking disease-associated ROS unbalance and ferroptosis-related chemoresistance. Targeting PRDX2 signaling by APE1-redox-specific inhibition provides a potential novel strategy for combined chemotherapies in refractory EAC.
Citation Format: Lei Chen, Heng Lu, Farah Ballout, Dunfa Peng, Zheng Chen, Jianwen Que, Steven Chen, Oliver McDonald, Alexander Zaika, Wael El-Rifai. APE1/NF-κB/PRDX2 activated by reflux conditions mediates chemoresistance in esophageal adenocarcinoma by suppressing ferroptosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3269.