Engineered In Vitro Tumor Model Recapitulates Molecular Signatures of Invasion in Glioblastoma.

Glioblastoma stem cells (GSCs) play an important role in the invasive nature of glioblastoma (GBM); yet, the mechanisms driving this behavior are poorly understood. To recapitulate tumor invasion in vitro, we developed a GBM tumor-mimetic hydrogel using extracellular matrix components upregulated in patients. We show that our hydrogel facilitates the infiltration of a subset of patient-derived GSCs, differentiating samples based on phenotypic invasion. Invasive GSCs are enriched for injury-responsive pathways while noninvasive GSCs are enriched for developmental pathways, reflecting established GSC stratifications. Using small molecule inhibitors, we demonstrate that the suppression of matrix metalloprotease and rho-associated protein kinase processes results in a significant reduction of cell invasion into the hydrogel, reflecting mesenchymal- and amoeboid-dependent mechanisms. Similar reduction in cell invasion was observed by siRNA knockdown of ITGB1 and FAK focal adhesion pathways. We elucidate the transcriptomic profile of cells invading in the hydrogel by performing bulk RNA sequencing of cells cultured in the hydrogel and compare these to cells cultured in conventional tissue culture polystyrene (TCP). In our 3D hydrogel cultures, invasion-related molecular signatures along with proliferation and injury response pathways are upregulated while development processes are downregulated compared to culture on 2D TCP. With this validated in vitro model, we establish a valuable tool to find therapeutic intervention strategies against cellular invasion in glioblastoma.