Abstract A049: Epithelial to mesenchymal transition confers sensitivity to cytotoxic agent Ophiobolin A via alterations in mitochondrial function and metabolic pathways

Abstract

Abstract Triple negative breast cancer (TNBC) is characterized by its high metastatic potential, resistance to therapeutics and elevated degree of disease reoccurrence. In patients with TNBC, metastasis occurs in approximately half of all cases and is tightly correlated with poor overall survival, made worse by limited therapeutic options. Metastatic events are hypothesized to be facilitated by the epithelial to mesenchymal transition (EMT), gaining enhanced self-renewal, migration, invasion and multidrug resistant capabilities. Thus, targeting these cells remains a primary therapeutic goal, despite significant difficulty. Previous attempts in pursuing these cells through cytotoxic chemotherapeutics or targeted agents has largely failed to significantly improve patient outcomes. However, the fungus-derived sesterterpenoid Ophiobolin A (OpA) has demonstrated nanomolar cytotoxic capabilities and a high therapeutic index, specific to EMT+cells in breast cancer. The properties conferring this sensitivity, and possible novel therapeutic target, though, remain unclear. As the drug-like small molecule presents a major therapeutic opportunity, the details of its mechanism of action must be determined. To this end, we generated mitochondrial cybrids and quantified activity in individual electron transport chain (ETC) complexes, and found OpA to act in a mitochondria-targeted manner. Expanding upon this, we designed an EMT based model of breast cancer and examined alterations in mitochondrial function and metabolic pathways. Targeted liquid chromatography-mass spectronomy of metabolites indicated significant variations in many of those involved in glycolysis, OXPHOS and glutaminolysis. Flow cytometry further revealed a significant decrease in membrane potential and increase in mitochondrial reactive oxygen species (ROS), indicating mitochondrial damage. Dynamic changes between OXPHOS and glycolysis were also detected via Seahorse Bioanalyzer. Transmission electron microscopy (TEM) images and fluorescent microscopy showed distinct alterations in mitochondrial morphology, spatial dynamics and network integrity. Finally, using targeted fluorescent staining, an increase in mitochondrial labile iron was uncovered. This work reveals novel metabolic variations in the context of EMT and exploitable therapeutic targets. Thus, based on these EMT-specific responses, we conclude that EMT imparts distinct alterations to mitochondrial function and metabolic pathways, conferring sensitivity to the cytotoxic effects of OpA. Citation Format: Haleigh Parker, Kayla Haberman, Alexander Kornienko, Antonio Evidente, Daniel Romo, Benny Kaipparettu, Joseph Taube. Epithelial to mesenchymal transition confers sensitivity to cytotoxic agent Ophiobolin A via alterations in mitochondrial function and metabolic pathways [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr A049.