SUN-211 Active Steroid Hormone Synthesis Renders Adrenocortical Cells Highly Susceptible to Type II Ferroptosis Induction

Abstract

Context: Cell death in the adrenal cortex is ill understood but of high clinical relevance. Resistance of adrenocortical carcinoma (ACC) to current treatment with mitotane and chemotherapy calls for an improved understanding of adrenal cortical cell death processes. Ferroptosis is an iron-dependent form of regulated cell death which is characterized by polyunsaturated lipids adrenic (AdA) and arachidonic acid (AA) peroxidation. Aim: To address the potential role of ferroptosis in the adrenal gland as a potential treatment target of ACC. Methods: Human ACC cells H295R, CU-ACC1 and 2 were used. Protein expression of key enzymes was determined by western blotting. Lipid peroxidation was quantified with BODIPY 581/591 and cell viability with CellTiterGlo after treatment with known inducers and inhibitors of ferroptosis and steroidogenesis, respectively. Results: Adrenocortical tissues are enriched in AdA and AA and express high levels of genes relevant to ferroptosis, such as glutathione peroxidase 4 (GPX4) and long-chain-fatty-acid CoA ligase 4 (ACSL4). Inhibition of GPX4 with RSL3 led to cell death in H295R, CU-ACC1 and 2 cells at EC50 values of 2.4x10-7, 8.1x10-7 and 1.5x10-8 M, respectively. The steroidogenesis inhibitor ketoconazole completely reversed RSL3 cytotoxicity in all three steroidogenic cell lines by reducing lipid peroxidation. Mitotane induced lipid peroxidation but inhibition of ferroptosis with liproxstatin did not protect mitotane-induced cell death. Conclusion: Adrenocortical cells are highly sensitive to ferroptosis due to active steroidogenesis. Triggering this form of cell death could present future novel treatment options against ACC.