Pro-survival Lipid Sphingosine-1-Phosphate Metabolically Reprograms T cell to Limit its Anti-Tumor Activity

Sphingosine 1-phosphate (S1P), a pro-tumor survival bioactive lysophospholipid, generated by sphingosine kinase 1 (SphK1), regulates lymphocyte egress into circulation via transducing S1P receptor 1 (S1PR1) signalling, and also plays a role in the differentiation of regulatory T cells and T helper-17 cells. However, the mechanisms by which receptor-independent SphK1/S1P signallng regulates anti-tumor T cell activity remain unknown. Using melanoma antigen gp100 reactive T cells deficient in Sphk1, we found that Pmel-Sphk1-/- T cells maintained central memory phenotype, showed higher mitochondrial respiration, and exhibited resistance to TGF-β mediated suppression. Mechanistically, we discovered a direct correlation between SphK1 generated intracellular S1P and PPARγ (peroxisome proliferator-activated receptor gamma) activity, which in turn regulate lipolysis in T cells. Genetic, molecular or pharmacologic inhibition of SphK1 or PPARγ improved metabolic fitness and anti-tumor activity of T cells. Further, inhibition of SphK1 and PD1 together led to long-term control of melanoma. Overall, these data highlight the clinical potential of targeting SphK1/S1P for improved anti-cancer adoptive T cell immunotherapy. Duplicate samples were analyzed from the WT and Sphingosine Kinase deficient mouse. The splenic T cells were activated wih cognate antigen (gp100) for three days before the RNA was prepared and RNA seq. performed.