A Cancer Cell-Intrinsic GOT2-PPARδ Axis Suppresses Antitumor Immunity

Despite signifi cant recent advances in precision medicine, pancreatic ductal adenocar-cinoma (PDAC) remains near uniformly lethal. Although immune-modulatory therapies hold promise to meaningfully improve outcomes for patients with PDAC, the development of such thera-pies requires an improved understanding of the immune evasion mechanisms that characterize the PDAC microenvironment. Here, we show that cancer cell-intrinsic glutamic-oxaloacetic transaminase 2 (GOT2) shapes the immune microenvironment to suppress antitumor immunity. Mechanistically, we find that GOT2 functions beyond its established role in the malate-aspartate shuttle and promotes the transcriptional activity of nuclear receptor peroxisome proliferator-activated receptor delta (PPAR delta), facilitated by direct fatty acid binding. Although GOT2 is dispensable for cancer cell proliferation in vivo , the GOT2-PPAR delta axis promotes spatial restriction of both CD4 + and CD8 + T cells from the tumor microenvironment. Our results demonstrate a noncanonical function for an established mitochondrial enzyme in transcriptional regulation of immune evasion, which may be exploitable to promote a productive antitumor immune response.SIGNIFICANCE: Prior studies demonstrate the important moonlighting functions of metabolic enzymes in cancer. We find that the mitochondrial transaminase GOT2 binds directly to fatty acid ligands that regulate the nuclear receptor PPAR delta, and this functional interaction critically regulates the immune microenvironment of pancreatic cancer to promote tumor progression.

Automated summary

Cancer cell-intrinsic glutamic-oxaloacetic transaminase 2 (GOT2) shapes the immune microenvironment to suppress antitumor immunity. The noncanonical function of transcriptional regulation of immune evasion opens up the potential for promoting antitumor immune response.