THE AXL INHIBITOR TP-0903 AND ARTESUNATE SYNERGISE TO INDUCE REACTIVE OXYGEN SPECIES, DNA DAMAGE AND APOPTOSIS IN TRIPLE NEGATIVE BREAST CANCER CELLS

Triple Negative Breast Cancer (TNBC) is an aggressive, often rapidly growing form of breast cancer. TNBC usually displays a basal molecular phenotype that associates with epithelial mesenchymal transition (EMT), a cellular program that confers chemoresistance and metastasis. Approximately 56% of TNBC cases show a basal-like gene expression profile and roughly 46% of TNBC patients have distant metastasis. In general, the absence of molecular targets in TNBC is the main obstacle for the development of an effective therapy. For example, TNBC does not respond to endocrine and anti-human epidermal receptor (HER2) treatments as it does not express estrogen and progesterone receptors (ESR/PgR) and human epidermal receptor 2 (HER2). In addition, though initially TNBC is more responsive to cytotoxic drugs compared to other subtypes, TNBC presents a higher relapse rate. Therefore, new anti-TNBC treatment strategies are urgently needed. Drug combination therapy for TNBC could rely on protocols whereby EMT reversal sensitizes TNBC to anti-cancer compounds that are effective against epithelial tumors. Recently, the anti-malaria compound Artesunate (ART) has been shown to exert cytotoxicity in breast cancer by generating reactive oxygen species (ROS) and DNA double strand breaks (DSBs). However, the effect was more pronounced in tumors of epithelial than mesenchymal origin. In this project, the hypothesis was to verify whether EMT inhibition could sensitize TNBC cell lines to ART cytotoxicity. To address this, two aims were pursued. Aim 1 verified whether receptor tyrosine kinase (RTK) AXL inhibitors TP-0903/R428 and AXL/ZEB1 knockdown sensitised TNBC cell lines to ART-generated ROS, DNA damage and apoptosis. Aim 2 was to test whether TP-0903 and AXL/ZEB1 knockout in TNBC cell lines suppressed expression of superoxide dismutase 1/2 (SOD1/2), glutathione peroxidase 8 (GPX8) and catalase (CAT)..