Abstract B006: Adhesion plasticity and bidirectional paracrine signaling cooperatively drive glioblastoma invasion

Abstract Glioblastoma (GBM) lethality stems from diffuse invasion beyond surgical margins. EGFR amplification is frequent, and constitutively active mutant EGFRvIII co-exists with wild-type EGFR (wtEGFR) cells in ∼50% of tumors, yet cell-intrinsic and extrinsic mechanisms coupling this heterogeneity to invasion remain unresolved. Murine astrocytes engineered with wtEGFR or EGFRvIII expression were interrogated across complementary 2-D, 3-D, and in-vivo platforms. Here, we found that EGFRvIII cells were ∼40% less adherent, enabling faster migration than their wtEGFR counterparts. EGFRvIII conditioned media reduced adhesion strength of wtEGFR cells, but direct co-culture showed bidirectional signaling, with both populations experiencing a two-fold decrease in adhesion strength. Cooperative adhesion reduction was induced by a secretome unique to co-cultured cells, further suggesting bidirectional communication. Adhesion changes also cause post-“education” differences in invasion mode; EGFRvIII cells alone disseminate in a follow-the-leader mode but switch to single cell scattering when co-cultured with wtEGFR (and similar to the wt cells only condition). In addition to mode, the extent of migration is impacted by co-culture; mixed co-culture spheroids invade the matrix more extensively (>2-fold) than spheroids of either population alone, mirroring how patient tumors heterogeneity scales with invasiveness and prognosis. Moreover, RNA-seq, cytokine-arrays, and intracranially injected in vivo mouse models identified transcriptional and signaling alterations that could drive GBM adhesion. Heterotypic interaction between wtEGFR and EGFRvIII induces remodeling of focal adhesions through a distinct paracrine program, highlighting cooperative invasion. Targeting this adhesion-modulating axis offers a strategy to limit diffuse GBM spread. Together, these data show that both intrinsic and extrinsic signaling propel glioma migration and nominate new therapeutic entry points to improve patient outcomes. Citation Format: Abhinaba Banerjee, Audrey Iwashita, Afsheen Banisadr, Frank Furnari, Adam Engler. Adhesion plasticity and bidirectional paracrine signaling cooperatively drive glioblastoma invasion [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 B006.