Abstract 6958: CRIPTO-regulated extracellular vesicles mediate heterotypic cellular crosstalk in triple negative breast cancers

Abstract Tumor progression involves dynamic interaction between various cell types within the tumor microenvironment. Fibroblasts, which normally participate in wound healing, reciprocally communicate with breast cancer cells to promote tumor cell plasticity and heterogeneity. Gaining insights into the molecular mechanisms underlying this cell-to-cell communication, could unlock novel therapeutic avenues for inhibiting cellular plasticity, breast cancer progression and metastasis. The small GPI-anchored adaptor protein CRIPTO is a key player in this context though important molecular details remain to be elucidated. CRIPTO orchestrates TGF-β pathway signaling as well as growth factor-like signaling pathways that activate c-Src/MEK/AKT, in an autocrine and paracrine manner. CRIPTO is expressed during mammary development, wound healing, and breast cancer but is largely undetectable in homeostatic tissue, making it a promising therapeutic target. Our previous studies have demonstrated that the activity of CRIPTO is contingent upon cellular stress, with pronounced influence within pro-fibrotic, hypoxic domains of tumors. Importantly, we have shown that inhibition of CRIPTO using the soluble recombinant protein antagonist A4Fc effectively impedes the progression of triple negative breast cancer (TNBC) in murine xenograft models. Building upon these findings, we have been dissecting CRIPTO’s role in coordinating fibroblast activation and cell-state reprogramming in TNBC. We find that inhibition of CRIPTO with A4Fc suppresses cancer associated fibroblast (CAF) activation and collagen remodeling in vivo. Further, by modeling tumor cell:fibroblast crosstalk in vitro, we have demonstrated mechanistically that CRIPTO expression in tumor cells mediates subsequent extracellular vesicle (EV) uptake by fibroblasts, as well as fibroblast SMAD pathway activation and priming for reciprocal signaling back to tumor cells to promote transcriptional reprogramming and cellular invasion.The significance of these findings lies in their elucidation of key EV control mechanisms that could be exploited to intervene in essential tumor cell:fibroblast crosstalk or to enhance targeting of therapeutic moieties based on EV architecture and function in cancer and/or normative regenerative processes. Citation Format: David W. Freeman, Brooke L. Gates, Mauri D. Spendlove, Benjamin T. Spike. CRIPTO-regulated extracellular vesicles mediate heterotypic cellular crosstalk in triple negative breast cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6958.