NEW PREDICTIVE MARKERS IN MALIGNANT PLEURAL MESOTHELIOMA DEVELOPMENT AND METASTASIS: CROSS-TALK BETWEEN OXIDATIVE STRESS AND EPITHELIAL-TO-MESENCHYMAL TRANSITION (EMT)

Malignant Pleural Mesothelioma (MPM) is a highly aggressive and lethal cancer strongly linked to asbestos exposure, which induces chronic Oxidative Stress and drives Epithelial-to-Mesenchymal Transition (EMT). We investigated the synergistic Oxidative Stress- EMT crosstalk by targeting possible key molecular mediators, the Redox-Sensitive Transcription Factor Ref-1 and the cytokine TGF-β, in MPM cell lines and 3D spheroids. We first confirmed the simultaneous overexpression of some Redox sensitive Transcription Factors (Nrf-2, Ref-1 and FOXM1) and EMT Transcription Factors (Twist, ZEB-1 and Snail-1) in MPM cells. Then, we saw the inhibition of Ref-1, factor related to both Oxidative stress and EMT, via Ref-1 inhibitor (E3330) or siRNA technique, significantly suppressed proliferation, induced G2/M arrest, and reversed EMT by downregulating Twist, thus confirming its central role as an Oxidative Stress- EMT link. Furthermore, TGF-β blockade, via siRNA and or in combination with Fresolimumab (TGF-β antibody) inhibited growth, promoted MET (Mesenchymal-to-Epithelial Transition) by upregulating E-cadherin and causing the cytoplasmic sequestration of EMT-TFs, and induced histotype-specific cell cycle arrests. Our findings establish the Oxidative Stress- EMT axis as fundamental to MPM aggressiveness. While targeting Ref-1 and TGF-β shows potent anti-tumorigenic efficacy in 3D spheroids, the necessity of a combined therapeutic strategy is important to circumvent complex transcriptional and signaling feedback loops, suggesting novel targets and biomarkers to improve MPM prognosis