Gene expression profile at single cell level of all CD45+ cells infiltrating B16-SIY-dsRed syngeneic tumors implanted subcutaneously after 26 days of tumor growth in Wildtype and PRKCD KO bone marrow engrafted animals
Based on the notion that hypomorphic germline genetic variants are linked to autoimmune diseases, we reasoned that novel targets for cancer immunotherapy might be identified through germline variants associated with greater T-cell infiltration into tumors­. Investigating germline polymorphisms associated with a tumor immune gene signature, we identified PKCd as a candidate. Genetic deletion of PKCd in mice resulted in improved endogenous anti-tumor immunity and increased efficacy of anti-PD-L1. Single cell RNAseq revealed myeloid cell expression of Prkcd, and PKCd deletion caused a shift in macrophage gene expression from an M2-like to an M1-like phenotype. Conditional deletion of PKCd in myeloid cells recapitulated improved tumor control that was augmented further with anti-PD-L1. Analysis of clinical samples confirmed an association between PRKCD variants and M1/M2 phenotype, as well as between a PKCd KO-like gene signature and clinical benefit from anti-PD-1. Our results identify PKCd as a candidate therapeutic target that modulates myeloid cell states. Overall design: Loss of hematopoietic PKC-delta results in an immune dependent delay in tumor growth. To investigate the mechanisms underlying this delay, we performed a scRNAseq analysis of immune cells isolated from tumors grown in C57BL/6 mice with either Prkcd+/+ or Prkcd-/- hematopoietic cells. B16-SIY tumors were implanted and live CD45.2+ cells were isolated from the tumor microenvironments via fluorescence activated cell sorting (FACS) after 26 days of tumor growth. Each sample is the combination from 2 independently grown tumors, each group is an N of 4 samples, collected across 2 independent collection days.