ID #331 Integrative Kinome Screening Identifies Hypoxia-Modulated VEGFR1 as a Therapeutic Vulnerability in Pediatric Medulloblastoma

Abstract

Medulloblastoma is the most common malignant brain tumor in childhood and displays marked molecular heterogeneity. Accumulating evidence indicates that dysregulated tyrosine kinases play a central role in tumor progression and microenvironmental adaptation, representing attractive targets for precision therapies. In this study, we investigated the functional dependency on tyrosine kinases in pediatric medulloblastoma using an integrated in silico and experimental approaches. Public transcriptomic analyses identified differentially expressed kinases associated with metastasis and reduced overall survival, highlighting VEGFR1 (FLT1) as a priority target, particularly enriched in Group 3 tumors and linked to adverse clinical outcomes. Correlation and functional enrichment analyses demonstrated that VEGFR1-associated genes converge on angiogenesis-related programs, focal adhesion, MAPK and PI3K-Akt signaling, supporting a role in tumor adaptation to microenvironmental stress. In vitro functional assays were performed in MED8A (Group 3) and D283 (Group 3/4) cell lines using the multi-target tyrosine kinase inhibitor Orantinib. Despite similarly low basal VEGFR1 expression under normoxic conditions, the two models displayed strikingly distinct drug responses, evidencing intrinsic tumor heterogeneity. D283 cells were significantly more sensitive, with an IC50 of 39.95 µM at 48 hours, whereas MED8A cells exhibited relative resistance, with an IC50 of 79.36 µM. Chemical hypoxia induced by cobalt chloride selectively activated the HIF-1α–VEGFR1 axis in D283 cells, resulting in a robust ∼30–35-fold upregulation of VEGFR1 expression accompanied by increased HIF1A levels, an effect not observed in MED8A. These findings demonstrate that VEGFR1 functional relevance is dictated by hypoxia-driven microenvironmental modulation rather than baseline expression, providing a mechanistic explanation for lineage-specific therapeutic sensitivity. Collectively, this study highlights hypoxia as a critical determinant of angiogenic vulnerability and reinforces the biological heterogeneity underlying therapeutic response in high-risk pediatric medulloblastoma. Support: FAEPA, CAPES, CNPq