Abstract B016: FGFR2 localization to primary cilia: Implications for glioblastoma

Abstract The main objective of this study is to elucidate the function of fibroblast growth factor receptor 2 (FGFR2) in glioblastoma pathogenesis, through its exclusion from primary cilia in the glioblastoma cells. Glioblastoma (IDH-wildtype WHO G4) is the most prevalent primary malignant brain cancer in adults, with very high mortality and short median survival that has not improved in the last decade. The genomic region involving FGFR2 (10q 23.3-26.3) is frequently a subject of loss-of-heterogeneity events in glioblastoma, and results in single allele FGFR2 deletion in about one-third of all cases. Such glioblastomas then tend to express less FGFR2, but if that contributes to accelerated progression of 10qdel tumors is not known since the strong tumor suppressor PTEN and other genes get deleted too. At the same time, most of the matched recurrent glioblastomas retain the same FGFR2 expression as the primary tumor. Interestingly, FGFR2 mutations are extremely rare in glioblastoma, suggesting these are selected against and that dynamic FGFR2 signaling is important in glioblastoma pathogenesis. We recently found that FGFR2 localizes to primary cilia in vivo and in cell lines, and that this is necessary for it to signal. Primary cilia integrate signaling pathways and mediate cell-to-cell communication. We hypothesized that during glioblastoma development, the glioblastoma cells preserve primary cilia through which FGFR2 signals to support tumor progression. This would make ciliary FGFR2 trafficking and signaling an interesting therapy target in glioblastoma. In this project, we use gene editing and rescue experiments to target cilia localization of FGFR2 in the glioblastoma cells, and then study their invasiveness using in vitro migration assays, cerebral-glioblastoma GLICO organoids and RNAseq. We subcloned selected 10q wild-type and 10qdel glioblastoma cell lines, and obtained clones with maximal ciliation (∼ 15-40%, depending on the cell line) and also those completely lacking cilia. In the 10qdel clones, we used CRISPR/Cas9-mediated for stable integration of either wild-type or mutated FGFR2 (dTV, not able to enter primary cilia and signal) into a safe harbor. Altogether, this panel of cell lines allowed us to study how ciliation combined with FGFR2 presence and/or mutation affected FGFR2 signaling in glioblastoma cells, and the glioblastoma invasiveness in vitro and within the brain organoids. Citation Format: Alexandru Nita, Eliska Cizkova, Martin Barak, Milan Hendrych, Radim Jancalek, Michaela Bosakova. FGFR2 localization to primary cilia: Implications for glioblastoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Brain Cancer; 2026 Mar 23-25; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2026;86(6_Suppl):Abstract nr B016.