Tumor Acidosis Remodels the Glycocalyx to Control Lipid Scavenging and Ferroptosis

Cancer cell adaptation to metabolic stress remains a major barrier to effective therapy. Here, we identify a chondroitin sulfate (CS)-enriched glycocalyx in the acidic microenvironment of human glioblastoma (GBM) and CNS metastases. Integrated analyses of patient GBM tumors and in vitro and in vivo models reveal that CS-glycocalyx encapsulation provides a physical barrier to lipid scavenging and mitigates lipid-induced toxicity in acidosis. Mechanistically, HIF and TGFß signaling converge to induce CS biosynthesis and dynamically reprogram syndecan-1 glycosylation from heparan sulfate (HS) to CS, limiting lipid particle uptake. Dual inhibition of CS biosynthesis and diacylglycerol-O-acyltransferase 1 (DGAT1), which blocks lipid storage, triggers uncontrolled lipid peroxidation and ferroptotic cell death. These findings uncover a stress-adaptive glycan program that insulates tumor cells from lipotoxic stress. Disrupting this glyco-metabolic barrier selectively sensitizes GBM cells in the lipid-rich, acidic microenvironment and reveals a therapeutic vulnerability that may be leveraged to overcome metabolic resilience in aggressive tumors. Overall design: Two biological replicates (500,000 cells each) were prepared for each of the following U87MG-derived conditions for HIF1a CUT&RUN sequencing (targeting 25 million reads per replicate): NA cells (U87MG cultured at pH 7.4) AA cells (U87MG cultured at pH 6.4) Ctrl cells (U87MG cultured in serum-free media at pH 7.4) DMOG-treated cells (U87MG treated with 0.5 mM dimethyloxalylglycine at pH 7.4) In addition, CUT&RUN was performed using IgG provided in the CUT&RUN Assay Kit (Active Motif, #53180, version 47) to serve as a control for normalization and peak calling in the HIF1a datasets.