MLKL PARylation in the endothelial niche triggers angiocrine necroptosis to evade cancer immunosurveillance and chemotherapy.

Chemoresistance is the leading cause of cancer-related death. How chemotherapy subjugates the cellular crosstalk in the tumour microenvironment to cause chemoresistance remains to be defined. Here we find chemotherapy enables immunosuppressive SDF1 endothelial niche to evade immunosurveillance in ovarian and breast cancers. We integrated human patient data and mouse models to show that chemotherapy selectively activates PARP1-SDF1 axis in tumour endothelial cells (ECs). This angiocrine SDF1 interferes with antitumour interplay between CXCL10 macrophages and CXCR3CD8 T cells and promotes tumour progression in ovarian and breast cancers. Proteome-based screening revealed that endothelial PARP1 PARylates MLKL, a key necroptosis effector to upregulate angiocrine SDF1 in ECs. In sum, we identify PARylation-dependent necroptosis in tumour ECs as an important step in subverting the tumour microenvironment to evade immunosurveillance.