TMIC-62. Astrocyte-expressed FASN as a novel candidate drug target for glioblastoma

Abstract BACKGROUND Glioblastoma (GBM) is an aggressive cancer requiring deeper understanding and new therapeutic approaches. The tumoral microenvironment guide cancer cell progression. Our previous studies demonstrated that astrocytes (ACs) enhance GBM proliferation, as evidenced by analyses of clinical samples and experimental studies. METHODS HTS screening (14000 compounds) was performed on co-cultured GBM cells and astrocytes. Tumor growth and self-renewal capacity were assessed via cell proliferation and tumor-sphere formation assays (Luc-GFP system). Human GBM specimens were analyzed using multiplex profiling to detect FASN+GFAP+ astrocytes and Ki67+ proliferative cancer cells. Mitochondrial transfer from ACs to GBM cells was quantified using confocal imaging and FACS. FASN inhibitors potency screening was used to correlate FASN cellular activity and co-culture activity. Non-FASN inhibitory hits were explored by Proteome Integral Solubility Alteration (PISA) Assay for target identification. RESULTS Primary screening identified approximately 130 specific hits. Bioinformatic analysis indicated fatty acid synthase (FASN) as an enriched target. FASN knockdown in astrocytes significantly reduced their support of GBM proliferation and self-renewal. Selected compound from screening showed reduced or no activity in co-cultures with FASN KD astrocytes. Strong correlation was observed between cellular FASN inhibitory potency and growth-inhibitory activity among FASN inhibitors. Free fatty acid supplementation rescued GBM growth in co-cultures with FASN-knockdown astrocytes but not in wild-type astrocyte co-cultures. FASN knockdown reduced mitochondrial transfer from astrocytes to GBM cells, while MIRO knockdown suggested mitochondrial transfer is essential for FASN-mediated AC-supported growth. PISA analyses of hits not targeting FASN also indicated effects on fatty acid metabolism. Preliminary multiplex staining demonstrated positive correlation between FASN-positive astrocytes and Ki67+EGFR+GBM cells in human samples. CONCLUSIONS Screening results, tissue profiling, and knockdown experiments collectively identify astrocyte-derived FASN and fatty acid metabolism as critical components of astrocyte-driven GBM growth. These findings are being developed through mechanistic studies, expanded human GBM profiling, and studies in in orthotopic mouse models using FASN-knockdown astrocytes and FASN inhibitors.