Intratumoral Heterogeneity in Interstitial Fluid Flow-Driven Glioblastoma Invasion

Abstract

Glioblastoma (GBM) is a highly aggressive brain tumor characterized by extensive intratumoral heterogeneity and diffuse invasion into surrounding tissue, contributing to poor patient outcomes and frequent recurrence. Interstitial fluid flow (IFF) has emerged as a potential driver of GBM invasion through mechanisms such as autologous chemotaxis mediated by the CXCL12/CXCR4 signaling axis. However, the extent to which heterogeneous tumor subpopulations differentially respond to IFF remains unclear. Here, patient-derived GBM cells were clonally expanded from distinct subcolonies and evaluated for invasion in response to flow using xenograft mouse models. Tumor growth, invasion, fluid flow dynamics, and CXCR4 expression were assessed through MRI-based modeling and fluorescent imaging. Subcolonies exhibited distinct phenotypes, with subcolony 1 (SC1) and subcolony 3 (SC3) forming larger tumors with higher flow velocities, while subcolony 4 (SC4) formed smaller, more diffuse tumors with increased relative invasion. In combination tumors, dominant subcolonies dictated overall tumor behaviors, though individual subpopulations retained their invasive characteristics. Interestingly, invasion correlated with high-flow regions in SC1 and SC3, whereas SC4 demonstrated increased invasion in lower-flow environments. Despite these differences, all subcolonies showed a positive correlation between active CXCR4 and fluid flow in peritumoral regions. SC4 displayed elevated active cXCR4 despite lower total CXCR4 expression, suggesting enhanced sensitivity to chemokine gradients. These findings support a model in which IFF promotes GBM invasion through CXCL12/CXCR4- mediated autologous chemotaxis, regulated by intratumoral heterogeneity. Targeting this pathway may provide a strategy to limit invasion and reduce recurrence in GBM.