UPF1 deficiency enhances mitochondrial ROS which promotes an immunosuppressive microenvironment in pancreatic ductal adenocarcinoma
Menée à l'aide d'un modèle murin d'adénocarcinome du pancréas, cette étude met en évidence un mécanisme par lequel une déficience de l'ARN hélicase UPF1 favorise le développement d'un microenvironnement tumoral immunosuppressif en augmentant la production d'espèces réactives de l'oxygène par les mitochondries
Upstream frameshift 1 (UPF1) is an RNA helicase involved in a number of mRNA regulatory processes including nonsense-mediated decay. Mutations in the UPF1 locus that reduce its expression have been associated with adenosquamous carcinoma of the pancreas, a particularly aggressive form of the disease. To determine the effect of Upf1 suppression in a murine model of pancreatic adenocarcinoma, we silenced with shRNA Upf1 in cells derived from an autochthonous tumor in an LSL-KrasG12D/+; Trp53R172H/+; Pdx-1Cre/+ mouse (KPC) and orthotopically implanted these cells in the pancreas of C57BL/6 mice. Tumors derived from Upf1-deficient cells were markedly larger than those derived from control cells, a difference observed only in immunocompetent mice. The immune infiltrate of Upf1-deficient tumors was enriched in myeloid-derived suppressor cells (MDSCs) and depleted of CD8+ cells compared to control KPC tumors. Upf1-deficient KPC cells secreted inflammatory cytokines including G-CSF and CXCL2, known to recruit MDSCs. Cytokine secretion from Upf1-deficient KPC cells was induced by increased levels of mitochondrial reactive oxygen species (ROS), which in turn were due to an increase in complex I activity in the electron transport chain. Thus, Upf1 helicase deficiency leads to increased mitochondrial complex I activity which produces ROS that signals for cytokine release that drives immune suppression and enhanced tumor growth.
Proceedings of the National Academy of Sciences , article en libre accès, 2023