Scherz-Shouval Lab

Cancer-associated fibroblasts (CAF) are abundant components of the breast tumor microenvironment and major contributors to immune-modulation. CAFs regulate the activity of many immune cells including T cells, macrophages, and dendritic cells; however, little is known about their interaction with NK cells, which constitute an important arm of antitumor immunity. Using mouse models of breast cancer and ex vivo cocultures, we find that CAFs inhibit NK cell cytotoxicity toward cancer cells. We unravel the mechanism by which suppression occurs, which is through ligandreceptor engagement between NK cells and CAFs, leading to CAF cytolysis and downregulation of activating receptor expression on NK cells, promoting cancer cell escape from NK cell surveillance. In patients with triple-negative breast cancer, we find enrichment of NK cells in CAF-rich regions and upregulation of NK-binding ligands on CAFs, which correlates with poor disease outcomes. These results reveal a CAF-mediated immunosuppressive decoy mechanism with implications for the treatment of carcinomas.

Tumors are supported by cancer-associated fibroblasts (CAFs). CAFs are heterogeneous and carry out distinct cancer-associated functions. Understanding the full repertoire of CAFs and their dynamic changes as tumors evolve could improve the precision of cancer treatment. Here we comprehensively analyze CAFs using index and transcriptional single-cell sorting at several time points along breast tumor progression in mice, uncovering distinct subpopulations. Notably, the transcriptional programs of these subpopulations change over time and in metastases, transitioning from an immunoregulatory program to wound-healing and antigen-presentation programs, indicating that CAFs and their functions are dynamic. Two main CAF subpopulations are also found in human breast tumors, where their ratio is associated with disease outcome across subtypes and is particularly correlated with BRCA mutations in triple-negative breast cancer. These findings indicate that the repertoire of CAF changes over time in breast cancer progression, with direct clinical implications.