Abstract PO050: EphA2 signaling segregation and modulation by diverse tumor microenvironment components differentially regulates cancer cell invasion and survival

Abstract The receptor tyrosine kinase EphA2 is overexpressed in many solid cancers and associated with disease aggressiveness and poor clinical outcome. EphA2 signaling mechanisms are complex, context-dependent and still not completely understood. In several cancers, EphA2-ephrinA1 interaction is associated with cell repulsion and growth suppressive signaling. Yet, this receptor can also be activated in a ligand-independent manner by crosstalk with growth factor receptors and adhesion molecules, and its signaling can be further regulated via proteolytic cleavage by the matrix metalloproteinase MT1-MMP (MMP14). Studying how such proteolytic events, duality in signaling modes and repulsive responses are co-regulated and coexist in cancer could reveal potential therapeutic opportunities. To this goal, we have here used human breast, ovarian and prostate cancer cells grown in 2D and 3D extracellular matrices (ECM), as mono- and co-cultures to mimic the confines provided by the tumor microenvironment. Our results revealed segregation of EphA2 signaling within cancer colonies, including EphA2-MMP14 co-internalization at the cancer cells confronting ephrinA1-expressing cells, in contrast to the stabilization of the receptor and induction of non-canonical signaling in the colonies. This separation of the ligand-mediated and non-canonical EphA2 signaling was dependent on MMP14 and affected platinum chemotherapy-induced apoptosis. By a mass spectroscopy-based screen for EphA2 interacting proteins in the different signaling contexts we identified regulators of proteolysis as well as endocytic pathways with differential interactions upon the ligand-dependent and independent activation states of this receptor. Our studies will help to understand the diverse EphA2 signaling modes and their impact on the regulation of cell-cell and cell-ECM communication affecting cell invasion and survival upon anti-cancer drug treatments. Citation Format: Lidia Moyano-Galceran, Pauliina S. Turunen, Nami Sugiyama, Pernilla von Nandelstadh, Erika Gucciardo, Markku Varjosalo, Kaisa Lehti. EphA2 signaling segregation and modulation by diverse tumor microenvironment components differentially regulates cancer cell invasion and survival [abstract]. In: Proceedings of the AACR Virtual Special Conference on the Evolving Tumor Microenvironment in Cancer Progression: Mechanisms and Emerging Therapeutic Opportunities; in association with the Tumor Microenvironment (TME) Working Group; 2021 Jan 11-12. Philadelphia (PA): AACR; Cancer Res 2021;81(5 Suppl):Abstract nr PO050.