Abstract Wrk2-02: Modelling the effects of cell-cell interactions in the tumor microenvironment from single cell variability

Abstract

Abstract Multicellular programs underly emergent phenotypes in health and disease. Yet, deciphering the functional effects of interactions amongst cell types remains a major challenge. Cells typically send messages to their microenvironment by emitting ligands, which bind to complimentary receptors on the surfaced of target cells; then triggering a change in the behavior of the target cell. Complimentary ligand-receptor-pairs are well annotated and methods have been developed to infer cell-cell interactions from single cell expression data based on their mutual expression. However, these methods do not assess the effect of ligand-receptor-mediated interactions on the microenvironment. Thus, we developed ContactTracing – a fundamentally new, systems level approach that exploits inter- and intra-sample variability to infer ligand effects on gene expression in target (receptor-expressing) cells without prior knowledge of downstream signaling (Nature, 2023). Foundational work towards benchmarking and validation of this method was performed in isogenic breast cancer models distinguished by tumor cell-intrinsic rates of chromosome missegregation (a cellular process called chromosomal instability, or CIN). Through this, we identified tumor ligands emanating from an endoplasmic reticulum (ER)-stress response as potential mediators of immune suppression in chromosomally unstable tumors. Indeed, CIN-induced chronic STING activation led to rapid interferon-selective desensitization and a switch to ER-stress-dependent transcription. Moreover, inhibition of chronic STING - or key mediators of its unfolded protein response to ER-stress - suppressed metastasis in syngeneic models of melanoma, breast and colorectal cancer; validating this innovative methodology and identifying a targetable mediator of cancer metastasis. Citation Format: A. Laughney. Modelling the effects of cell-cell interactions in the tumor microenvironment from single cell variability [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr Wrk2-02.