Proteomic analysis reveals fibroblast growth factor receptor substrate 2 as a hub for FGFR-driven cytoskeleton and cell junction regulation

The scaffold protein FRS2 is central to FGFR signaling, linking receptor activation to MAPK/ERK and PI3K/AKT pathways. Elevated FRS2 expression correlates with aggressive tumor phenotypes and poor prognosis across multiple cancers, including medulloblastoma (MB). Here, we characterized FRS2's subcellular localization and interactome in MB cells, employing live-cell imaging, phosphoproteomics, immunoprecipitation, and APEX2-based proximity labeling. This study demonstrates that increased motile and invasive behavior in MB tumor cells is associated with increased FRS2 expression. We identified novel FRS2-associated proteins involved in actin cytoskeleton remodeling, cell junction assembly, and translation initiation, revealing a growth factor-dependent reorganization of the FRS2 signalosome. We furthermore functionally confirmed FRS2's role in directing localization of key effectors such as WASF2 and TJP1. These findings position FRS2 as a spatial regulator linking FGFR activation to cellular processes governing migration, invasion, and proliferation. Furthermore, our study provides a framework for exploring the FRS2 interactome as a possible target to attenuate FGFR-driven oncogenic processes with next-generation therapeutic strategies.