Abstract 3973: Tumor-associated macrophages protect glioblastoma cells from ferroptotic stress in a sex-biased manner by inducing ferritin-bound iron release from cancer cells

Abstract Glioblastoma (GBM) is a highly aggressive and difficult-to-treat brain tumor originating from astrocytes. It is also sexually dimorphic, with females having a survival advantage and responding better to standard therapy. Sex-biased differences in iron metabolism play a significant role in making GBM a sexually dimorphic disease. Iron is a critical player in tumor metabolism, as cancer cells require iron to keep dividing rapidly; however, high cellular iron can make the cells vulnerable to ferroptosis. Macrophages play a pivotal role in tumorigenesis by regulating iron homeostasis in the tumor microenvironment. Here, we examine macrophage iron homeostasis as a potential driver of sex biases in glioblastoma using bone marrow-derived macrophages (BMDM) isolated from C57BL/6 mice. Immunoblot analysis shows that male macrophages have a higher storage (FTL expression) than female macrophages. We used a stable isotope of iron (Fe57) to determine macrophage iron uptake by ICPMS and observed that male BMDMs have a higher iron uptake. Flow cytometric analysis after ferro far red staining showed that male macrophages have a higher labile iron pool. These results indicate that macrophage iron metabolism is sexually dimorphic. Next, we used a transwell co-culture system to study how macrophages regulate the iron status of GL261 cells. Immunoblot analysis showed that GL261 cells cocultured with BMDMs had a significant reduction in cellular FTH1 in a sex-biased manner. This reduction in cellular FTH1 correlated with decreased total cellular iron. Further immunoblot analysis of the condition media revealed increased secreted FTH1 levels from GL261 cells in coculture. Fe57 loading experiments showed that this increased secreted FTH1 levels correlated with an increased iron secretion. All these results indicate that macrophages induce FTH1-bound iron release in GL261 cells in a sex-biased manner. To understand if this cellular decrease in iron alters the GBM cells’ susceptibility to ferroptotic stress, we induced ferroptosis by RSL3 treatment. Upon RSL3 treatment, GL261 cells in coculture with BMDMs had significantly higher cellular viability (Cell titer glo) and significantly less lipid peroxidation (Bodipy Staining). This indicates that tumor-associated macrophages protect GBM cells from ferroptotic stress in a sex-biased manner by inducing the cellular release of iron-containing FTH1. Citation Format: Aurosman Pappus Sahu, Kondaiah Palsa, Ganesh Shenoy, Becky Slagle-Webb, James R. Connor. Tumor-associated macrophages protect glioblastoma cells from ferroptotic stress in a sex-biased manner by inducing ferritin-bound iron release from cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3973.