Abstract P67: n-Butylidenephthalide Induces Ferroptosis in ALDH+ Cancer Stem Cells of High-Grade Serous Ovarian Cancer

Abstract Type II high-grade serous ovarian cancer (HGSOC) represents approximately 80% of all ovarian cancer cases, with cancer stem cells (CSCs) contributing to tumor metastasis and chemoresistance. n-Butylidenephthalide (BP), a compound with known anti-tumor activity, was evaluated in this study for its ferroptosis-inducing effects in HGSOC. CSCs were isolated from KURAMOCHI and OVSAHO cell lines using the ALDH marker. Cell viability, proliferation, IC50 (half-maximal inhibitory concentration), TUNEL (Terminal deoxynucleotidyl transferase dUTP nick end labeling) assay, and Western blot analysis were performed, along with qPCR for ferroptosis-related genes. In vivo experiments used a subcutaneous xenograft mouse model with stemness-enriched CSCs, assessed via IVIS (In Vivo Imaging Systems) imaging. Treatment groups included control, BP, BP plus Taxol, and BP plus ferrostatin. BP treatment significantly reduced the viability of KURAMOCHI and OVSAHO ovarian cancer cells, with greater sensitivity observed in ALDH+ stem-like populations. This cytotoxic effect was mediated through ferroptosis, as evidenced by increased lipid peroxidation, ROS (reactive oxygen species) production, and downregulation of GPX4 and HMBOX1. Co-treatment with ferroptosis inhibitors reversed these effects. BP enhanced the anti-tumor activity of Taxol both in vitro and in vivo, and suppressed tumor growth in xenograft models, confirming its ferroptosis-dependent therapeutic potential. In summary, BP induces ferroptosis in ovarian cancer cells, particularly in ALDH+ CSCs, by modulating oxidative stress pathways and ferroptosis markers. Its ability to enhance Taxol sensitivity highlights its potential as a therapeutic strategy against chemoresistant HGSOC. Citation Format: Dah-Ching Ding. n-Butylidenephthalide Induces Ferroptosis in ALDH+ Cancer Stem Cells of High-Grade Serous Ovarian Cancer [abstract]. In: Proceedings of Frontiers in Cancer Science 2025; 2025 Nov 5-7; Singapore. Philadelphia (PA): AACR; Cancer Res 2026;86(13_Suppl):Abstract nr P67.