Pancreatic cancer remains a devastating disease with limited therapeutic options. Accumulating evidence shows that cancer-associated fibroblasts (CAFs) and tumor-associated macrophages, the predominant cells in the pancreatic cancer (PDAC) tumor microenvironment, hinder antitumor immunity. However, the role of extracellular vesicles (EVs) in such a process is poorly understood. In this study, using human bone marrow–derived monocytes and PDAC tumor cells, we showed that tumor cell–derived EVs (TC-EVs) induced monocyte differentiation toward M2-like, immunosuppressive, CD200R+PD-L1+HLA-DRlo macrophages that express ALOX15B, that we identify as an independent PDAC poor-prognosis biomarker using a human PDAC metacohort. We also demonstrated that TC-EVs reprogrammed human primary PDAC CAFs, causing a fibronectin network reorganization associated with changes in extracellular matrix (ECM) composition, including alterations of WNT pathway elements such as secreted frizzled related protein-1 (SFRP1) enrichment. We also revealed that monocytes cultured on SFRP1–enriched ECM differentiated into M2-like, immunosuppressive macrophages. Last, we demonstrated that both directly and indirectly TC-EV– or SFRP1-enriched ECM–driven differentiated macrophages hindered T cell activation and subsequent antitumor activity. Our findings highlight potentially novel dual mechanisms of TC-EV–mediated crosstalk, involving ALOX15B+ macrophages and SFRP1+ CAFs, that simultaneously contribute to foster the immunosuppressive ecosystem of PDAC.
Zainab Hussain, Claudio Montenegro, Christopher Rovera, Djamila Belghoula, Sarah Simha Tubiana, Pascal Finetti, Eugenie Lohmann, Magda Rodrigues, Thomas Bertran, Ghislain Bidaut, Daniel Isnardon, Sophie Vasseur, Francois Bertucci, Stephane Audebert, Luc Camoin, Moacyr Rego, Richard Tomasini