BIOM-15. GLIOBLASTOMA CELLS SHOW ELEVATED CHITINASE 3-LIKE PROTEIN 1 GENE EXPRESSION IN RESPONSE TO HUMAN CEREBROSPINAL FLUID WITH INCREASED MIGRATION AND EPITHELIAL-MESENCHYMAL TRANSITION RELATED ACTIVITY

Abstract

Abstract Glioblastoma (GBM) is the most common and malignant primary brain tumor in adults. GBM tumors proximal to the lateral ventricles have a worse prognosis with multifocality, recurrence, and lower overall survival. Studies suggest this increased aggressiveness is attributed to cerebrospinal fluid (CSF), as we have previously observed transcriptomic changes in GBM cells upon CSF exposure. GlioVis database reveals chitinase 3-like protein 1 (CHI3L1), a glycoprotein secreted by immune and cancer cells, is associated with poor prognosis and co-expressed with pro-inflammatory and tissue remodeling genes. We suggest exposure to CSF elevates CHI3L1 expression, consequently impacting malignancy-associated gene expression in patient-derived GBM lines. We first evaluated if patient CSF influences the expression of CHI3L1. GBM cells were treated with artificial CSF, non-cancer CSF, or cancer CSF for 72 hours. qPCR revealed significant increases in CHI3L1 (p< 0.0001), SPP1, and CD44 expression in cancer CSF groups compared to artificial CSF. CHI3L1 expression at the protein level is also increased by cancer CSF when profiled using Western Blot. Additionally, ELISA results indicated significantly higher levels of CHI3L1 in CSF samples obtained from patients with high-grade tumors compared to non-cancer samples. Next, we assessed if exogenous CHI3L1 stimulates GBM malignancy at the cellular level. An effective concentration of recombinant human CHI3L1 was determined through Alamar Blue assay, showing 500 ng/ml CHI3L1 increases viability in primary patient cell lines compared to non-treated media. Recombinant CHI3L1 also increases cell migration in Transwell assay. qPCR revealed Vimentin (p< 0.001) and Twist (p< 0.0001) expression significantly increases while E-cadherin (p< 0.001) significantly decreases in CHI3L1-treated groups, consistent with EMT and migratory activity. Ultimately, this study shows CHI3L1 is a CSF-induced factor in GBM and could be a therapeutic target as it enhances tumor malignancy by increasing proliferation, migration, and malignancy-promoting gene expression.