Several studies have reported mitochondrial dysfunction in rheumatoid arthritis (RA). Many nuclear DNA (nDNA) encoded proteins translocate to mitochondria, but their participation in the dysfunction of this cell organelle during RA is quite unclear. In this study, we have carried out an integrative analysis of gene expression, protein-protein interactions (PPI) and gene ontology data. The analysis has identified potential implications of the nDNA encoded proteins in RA mitochondrial dysfunction. Firstly, by analysing six synovial microarray datasets of RA patients and healthy controls obtained from the gene expression omnibus (GEO) database, we found differentially expressed nDNA genes that encode mitochondrial proteins. We uncovered some of the roles of these genes in RA mitochondrial dysfunction using literature search and gene ontology analysis. Secondly, by employing gene co-expression from microarrays and collating reliable PPI from seven databases, we created the first mitochondrial PPI network that is specific to the RA synovial joint tissue. Further, we identified hubs of this network, and moreover, by integrating gene expression and network analysis, we found differentially expressed neighbours of the hub proteins. The results demonstrate that nDNA encoded proteins are (i) crucial for the elevation of mitochondrial reactive oxygen species (ROS) and (ii) involved in membrane potential, transport processes, metabolism and intrinsic apoptosis during RA. Additionally, we proposed a model relating to mitochondrial dysfunction and inflammation in the disease. Our analysis presents a novel perspective on the roles of nDNA encoded proteins in mitochondrial dysfunction, especially in apoptosis, oxidative stress-related processes and their relation to inflammation in RA. These findings provide a plethora of information for further research.

ObjectiveImmunotherapy for the treatment of pancreatic ductal adenocarcinoma (PDAC) has shown limited efficacy. Poor CD8 T-cell infiltration, low neoantigen load and a highly immunosuppressive tumour microenvironment contribute to this lack of response. Here, we aimed to further investigate the immunoregulatory function of focal adhesion kinase (FAK) in PDAC, with specific emphasis on regulation of the type-II interferon response that is critical in promoting T-cell tumour recognition and effective immunosurveillance.DesignWe combined CRISPR, proteogenomics and transcriptomics with mechanistic experiments using a KrasG12Dp53R172Hmouse model of pancreatic cancer and validated findings using proteomic analysis of human patient-derived PDAC cell lines and analysis of publicly available human PDAC transcriptomics datasets.ResultsLoss of PDAC cell-intrinsic FAK signalling promotes expression of the immunoproteasome and Major Histocompatibility Complex class-I (MHC-I), resulting in increased antigen diversity and antigen presentation by FAK-/- PDAC cells. Regulation of the immunoproteasome by FAK is a critical determinant of this response, optimising the physicochemical properties of the peptide repertoire for high affinity binding to MHC-I. Expression of these pathways can be further amplified in a STAT1-dependent manner via co-depletion of FAK and STAT3, resulting in extensive infiltration of tumour-reactive CD8 T-cells and further restraint of tumour growth. FAK-dependent regulation of antigen processing and presentation is conserved between mouse and human PDAC, but is lost in cells/tumours with an extreme squamous phenotype.ConclusionTherapies aimed at FAK degradation may unlock additional therapeutic benefit for the treatment of PDAC through increasing antigen diversity and promoting antigen presentation.

Cancer immunotherapy has greatly improved the quality of life of cancer patients and it hinges on the discovery of novel cancer antigens that could be targeted to improve disease outcomes. The creation of databases such as IEDB, SysteMHC, TANTIGEN, caAtlas, HLA Ligand Atlas, Cancer Antigenic Peptide Database, SPENCER and IEAtlas support the immunopeptidomics community in understanding the landscape of antigen presentation. We have developed a pan-cancer, pan-HLA, and pan-tissue database containing immunopeptidomics data mapped to transcriptomic, genomic, immunological and biochemical data. The database was generated from 80 different publicly available immunopeptidomics mass spectrometry datasets collected between 2015-2022 (76 cancer and 4 normal datasets), covering 15 different types of cancers and 152 different HLA-I alleles. The peptides contained in our database were obtained by a combination of closed, open and de novo searches using an in-house developed computational pipeline. Following rigorous false discovery rate estimation at 1% and a second-round search to eliminate any false signals that may not have been detected in the previous round of FDR estimation, we obtained a list of 11.2 million peptide-HLA combinations comprising both coding and non-coding regions of the genome as well as bacterial peptides. These peptides have been mapped to chromosomal coordinates to facilitate adoption by the genomics community of this useful resource on antigen presentation. Pathway/biochemical analysis of each peptide was performed using the rWikiPathways package. Finally, mutations associated with each peptide were annotated using COSMIC and dbSNP resources. Our database includes a FAIR knowledge graph which contextualizes and enriches the data to enable clinicians to take effective therapeutic decisions on the appropriate form of treatment for cancer immunotherapy with the case study of clear cell renal cell carcinoma (ccRCC). We will continue to expand our database with new data over the next two years and expand the scope of its applications to facilitate uptake by the larger scientific community. Citation Format: Ashwin Adrian Kallor, Michał Waleron, Georges Bedran, Patrícia Eugénio, Catia Pesquita, Daniel Faria, Fabio Massimo Zanzotto, Christophe Battail, Ajitha Rajan, Javier Alfaro. CARMEN: A pan-HLA and pan-cancer proteogenomic database on antigen presentation to support cancer immunotherapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6577.

Immunotherapy for the treatment of Pancreatic Ductal Adenocarcinoma (PDAC) has shown limited efficacy. Poor CD8 T-cell infiltration, low neoantigen load and a highly immunosuppressive tumor microenvironment are key factors that contribute to this lack of response. Here, we identify a novel role for Focal Adhesion Kinase (FAK) in regulating type-II interferon signalling in human and murine PDAC cells and tumors, leading to suppression of antigen processing and presentation pathways critical for T-cell tumor recognition. We find that FAK loss promotes expression of the immunoproteasome and MHC-I, resulting in a significant increase in the diversity of antigens presented by FAK-/- PDAC cells. We show that regulation of the immunoproteasome subunit Psmb8 (β5i) is a critical determinant of this response, optimising the physicochemical properties of the peptide repertoire for high-affinity binding to MHC-I. Expression of the immunoproteasome and MHC-I can be further amplified in a STAT1-dependent manner via co-depletion of FAK and STAT3, leading to extensive CD8 T-cell infiltration into PDAC tumors and further restraint of tumor growth. Regulation of antigen processing and presentation by FAK preferentially occurs in human and murine PDAC cells and tumors of the classical/progenitor molecular subtype, further suggesting that precision medicine approaches based on molecular subtyping should be integrated into current and future clinical testing of FAK targeted therapies for the treatment of pancreatic cancer. Citation Format: Marta Canel, Aleksandra Slawinska, David W. Lonergan, Ashwin A. Kallor, Rosie Upstill-Goddard, Catherine Davidson, Alex von Kriegsheim, Andrew V. Biankin, Adam Bryron, Javier Alfaro, Alan Serrels. FAK suppresses antigen processing and presentation to promote immune evasion in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C019.

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