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CIAP1/2 antagonism induces antigen-specific T cell dependent immunity

ABSTRACT: Checkpoint blockade immunotherapy has failed in pancreatic cancer and other poorly responsive tumor types in part due to inadequate T cell priming. Naïve T cells can receive co-stimulation not only via CD28 but also through TNF superfamily receptors that signal via NF-κB. Antagonists of the ubiquitin ligases cIAP1/2, also called SMAC mimetics, induce degradation of cIAP1/2 proteins, allowing for the accumulation of NIK and constitutive, ligand-independent activation of alternate NF-κB signaling that mimics co-stimulation in T cells. In tumor cells, cIAP1/2 antagonists can increase TNF production and TNF-mediated apoptosis; however, pancreatic cancer cells are resistant to cytokine-mediated apoptosis, even in the presence of cIAP1/2 antagonism. Here, we confirm our previous findings that even poorly immunogenic tumors with a paucity of T cells can experience T cell-dependent anti-tumor immunity, and we provide transcriptional clues into how these rare T cells coordinate downstream immune responses.

ORGANISM(S): Mus musculus

PROVIDER: GSE222095 | GEO | 2023/01/25

REPOSITORIES: GEO

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Project description:Background: Cancer immunotherapeutic strategies showed unprecedented results in the clinic. However, many patients do not respond to immuno-oncological treatments due to the occurrence of a plethora of immunological obstacles, including tumor intrinsic mechanisms of resistance to cytotoxic T cell attack. Thus, a deeper understanding of these mechanisms is needed to develop successful immunotherapies. Methods: To identify novel genes that protect tumor cells from effective T cell-mediated cytotoxicity, we performed a genetic screening in pancreatic cancer cells challenged with TILs and antigen-specific T cells. Results: The screening revealed 108 potential genes that protected tumor cells from T cell attack. Among them, salt-inducible kinase 3 (SIK3) was one of the strongest hits identified in the screening. Both genetic and pharmacological inhibition of SIK3 in tumor cells dramatically increased T cell-mediated cytotoxicity in several in vitro co-culture models, using different sources of tumor and T cells. Consistently, adoptive T cell transfer of TILs led to tumor growth inhibition of SIK3 depleted cancer cells in vivo. Mechanistic analysis revealed that SIK3 rendered tumor cells susceptible to TNF secreted by tumor-activated T cells. SIK3 promoted NF-ΚB nuclear translocation and inhibited Caspase-8 and -9 after TNF stimulation. Chromatin accessibility and transcriptome analyses showed that SIK3 knockdown profoundly impaired the expression of pro-survival genes under the TNF-NF-ΚB axis. TNF stimulation led to SIK3-dependent phosphorylation of the NF-κB upstream regulators inhibitory-κB kinase (IKK) and NF-kappa-B inhibitor alpha (IκBα) on the one side, and to inhibition of histone deacetylase 4 (HDAC4) on the other side, thus sustaining NF-κB activation and nuclear stabilization. A SIK3 dependent gene signature of TNF-mediated NF-κB activation was found in a majority of pancreatic cancers where it correlated with increased cytotoxic T cell activity and poor prognosis.

Project description:The NF-κB pathway is a master regulator of inflammatory processes and is implicated in insulin resistance and pancreatic beta cell dysfunction in the metabolic syndrome. While canonical NF-κB signaling is well studied, there is little information on the divergent non-canonical NF-κB pathway in the context of pancreatic islet dysfunction in diabetes. Here, we demonstrate that pharmacological activation of the non-canonical NF-κB inducing kinase (NIK) disrupts glucose homeostasis in zebrafish in vivo. Further, we identify NIK as a critical negative regulator of beta cell function as pharmacological NIK activation results in impaired glucose-stimulated insulin secretion in mouse and human islets. NIK levels are elevated in pancreatic islets isolated from diet-induced obese (DIO) mice, which exhibit increased processing of non-canonical NF-κB components p100 to p52, and accumulation of RelB. Tumor necrosis factor α (TNFα) and receptor activator of NF-κB ligand (RANKL), two ligands associated with diabetes, induce NIK in islets. Mice with constitutive beta cell intrinsic NIK activation present impaired insulin secretion with DIO. NIK activation triggers the non-canonical NF-κB transcriptional network to induce genes identified in human type 2 diabetes genome-wide association studies linked to beta cell failure. These studies reveal that NIK contributes a central mechanism for beta cell failure in diet-induced obesity. We identify a role for Nuclear Factor inducing κB (NIK) in pancreatic beta cell failure. NIK activation disrupts glucose homeostasis in zebrafish in vivo and impairs glucose-stimulated insulin secretion in mouse and human islets in vitro. NIK activation also perturbs beta cell insulin secretion in a diet-induced obesity mouse model. These studies reveal that NIK contributes a central mechanism for beta cell failure in obesity. To uncover the role of NIK in pancreatic beta cells, we performed a gene expression microarray analysis comparing pancreatic islets with constitutive beta cell intrinsicNIK activation from the 16 week old mice (beta cell specific TRAF2 and TRAF2 knockout mice) to their controls (n=3 per group).

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CIAP1/2 antagonism induces antigen-specific T cell dependent immunity

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