CSIG-23. ALTERATIONS IN THE TRANSSULFURATION PATHWAY DRIVE GLIOBLASTOMA INVASION IN THE PERITUMORAL WHITE MATTER

Abstract

Abstract Glioblastoma is the most common and lethal adult brain tumor with a median survival under two years. The poor prognosis glioblastoma carries is largely due to cellular invasion, which enables escape from resection and drives inevitable recurrence. Although numerous molecular factors have been proposed as driving glioblastoma invasion, the search for targetable pathways to mediate glioblastoma invasion has been largely unfruitful. Despite a well-established relationship between metabolic reprogramming and cancer cell survival, little attention has been paid to the metabolic alterations needed for invading tumor cells to thrive in peritumoral white matter. To address this knowledge gap, we defined the links between tumor metabolism and invasion using metabolomics, transcriptomics, and CRISPR screens in biomimetic 3D hydrogels and regional biopsies of patient glioblastomas. Metabolomic and lipidomic screening of 315 metabolites and 691 lipids revealed cystathionine, a cysteine precursor in glutathione synthesis in the transsulfuration pathway, as well as hexosylceramides and glucosyl-ceramides, which counteract oxidative stress, to be enriched in invasive tumor cells in hydrogels and patient samples. Immunostaining confirmed elevated secondary ROS markers in invasive GBM cells in hydrogels and patient specimens. While adding ROS promoted GBM invasion in hydrogels, ROS sequestration had no effect. A CRISPR screen of 3000 metabolic genes revealed cystathionine gamma lyase (CTH), which catalyzes the last step in the transsulfuration pathway, to be essential for glioblastoma invasion. Genetic and pharmacologic CTH inhibition suppressed glioblastoma invasion in hydrogels in a manner rescued by exogenous cysteine. Thus, invasive glioblastoma cells exhibit high ROS levels, metabolic adaptations to ROS, and increased invasion in response to ROS. While targeting ROS directly did not slow invasion, targeting metabolic adaptations to ROS in the transsulfuraton pathway suppressed invasion. Our work defines the first link between metabolic adaptations and glioblastoma invasion, intriguing findings warranting future exploration.