MAGE-A4 TCR-like antibody IP in human lung and colon tissue
Ontology highlight
ABSTRACT:
INSTRUMENT(S): Q Exactive HF-X
ORGANISM(S): Homo Sapiens (human)
TISSUE(S): Lung, Colon
SUBMITTER: 
Nicola Ternette
LAB HEAD: Nicola Ternette
PROVIDER: PXD048295 | Pride | 2024-03-30
REPOSITORIES: Pride
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Project description:To demonstrate the on-target binding of the MAGE-A4 antibody to the target HLAp GVYDGREHTV, we developed a reverse immunopeptidomics strategy that uses the HLAp-targeting antibody as a bait to enrich interacting HLAp from A375 xenografts. For this purpose, we immobilized the IgG-format of the MAGE-A4 TCR-like antibody on Protein A beads by cross-linking, and exposed the molecule to the solubilized proteome, including membrane bound HLAp, of the A375 xenografts. We subsequently eluted the interacting HLAp bound to the MAGE-A4 antibody and purified the HLA-associated peptides through a 5 kDa molecular weight filter before liquid chromatography tandem mass spectrometry analysis for sequence determination.
2024-04-02 | PXD048298 | Pride
Project description:To demonstrate the on-target binding of the MAGE-A4 antibody to the target HLAp GVYDGREHTV, we developed a reverse immunopeptidomics strategy that uses the HLAp-targeting antibody as a bait to enrich interacting HLAp from A375 xenografts. For this purpose, we immobilized the IgG-format of the MAGE-A4 TCR-like antibody on Protein A beads by cross-linking, and exposed the molecule to the solubilized proteome, including membrane bound HLAp, of the A375 xenografts. We subsequently eluted the interacting HLAp bound to the MAGE-A4 antibody and purified the HLA-associated peptides through a 5 kDa molecular weight filter before liquid chromatography tandem mass spectrometry analysis for sequence determination.
2024-03-30 | PXD048297 | Pride
Project description:We chose to perform a head-to-head immune-enrichment from primary liver tissue resections using both, MAGE-A4 and ESK1 TCR-like antibodies. Since both target antigens MAGE-A4 and WT-1 are not expressed in hepatocytes (Human Protein Atlas, www.proteinatlas.org), the ESK1 enrichment could serve as isotype control for the MAGE-A4 antibody, and vice versa.
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Project description:Immunopeptidomics analyses of HCT116 cells +/- PRMT5 inhibition
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Project description:Immunopeptidomics analyses of CT26 cells +/- PRMT5 inhibition
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Project description:10 cervical cancer tissue tumour resections were analysed using an immunopeptidomics workflow.
2024-01-26 | PXD046182 | Pride
Project description:Our extended analysis of the HLA-presented antigen landscape in cervical cancer cells using an integrative proteogenomics approach identifies, next to tumour-associated antigens and tumour-specific neoantigens, presentation of viral canonical, and alternative reading frame (ARF)-derived HLA-presented sequences, including peptides derived from HPV-E1.
2023-03-11 | PXD028738 | Pride
Project description:Tumor antigens are central to antitumor immunity. Recent evidence suggests that peptides from non-canonical (nonC) aberrantly translated proteins can be presented on HLA-I by tumor cells. Here, we investigated the presentation and immunogenicity of nonC antigens across different cancer types to better understand their contribution to cancer immunosurveillance and to address whether they could be exploited therapeutically. To this end, we employed a proteogenomics pipeline to identify nonC HLA-I ligands derived from off-frame translation of coding sequences and non-coding regions (UTR, ncRNA, intronic and intergenic) in patient-derived tumor cell lines (TCL) of different histological types (4 gynecological cancer, 3 melanoma and 2 head and neck cancer patients). First, peptides bound to HLA-I were isolated and analyzed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) using state-of-the-art procedures. Amino acid (Aa) sequences were identified through the previously described pipeline Peptide-PRISM, with some modifications. Briefly, for each MS spectrum, the top 10 candidates were first identified by de novo sequencing and later mapped to a database including the 3-frame transcriptome and 6-frame genome. Additionally, whole-exome sequencing (WES) information of each TCL was included to interrogate the presentation of mutated peptides derived cancer-specific NSM. The false-discovery rate (FDR) was calculated independently for each category considering the search space and peptide length in a stratified mixture model as previously described. Next, in order to select nonC peptides preferentially presented by tumor cells, immunopeptidomics data from several healthy tissues and samples available from the HLA ligand atlas was used to filter out peptides presented in healthy tissues. To overcome a potential bias toward frequent alleles, the peptides were excluded at the ORF level rather than the Aa sequence. As a result, we found that from a total of 839 unique nonC peptides detected in our tumor samples, 38.5% were predicted to derive from ORFs also present in healthy tissue (nonC-HL). Hence, 61.6% (n=517) were considered preferentially presented on tumor HLA-I, referred to as non-canonical tumor ligands (nonC-TL). Out results showed that, although nonC-TL constitued the most abundant source of candidate tumor antigens, as compared to neoantigens, cancer-germline or melanoma-associated antigens, pre-existing antitumor T cells in cancer patients preferentially recognized neoantigens rather than nonC-TL. Nonetehless, nonC-TL elicited de novo T-cell responses via in vitro sensitization of donor lymphocytes. We identified TCRs specific to three nonC-TL, two of which mapped to the 5’ UTR regions of HOXC13 and ZKSCAN1, and one mapping to a non-coding spliced variant of the C5orf22C. These immunogenic nonC-TL were expressed across tumor types but were barely or not detected in healthy cells. Our findings predict a limited contribution of nonC-TL to cancer immunosurveillance but demonstrate they are attractive novel targets for widely applicable immunotherapies.
2023-02-03 | PXD036856 | Pride
Project description:Background: Patient derived organoids (PDOs) can be established from colorectal cancers as in vitro models to interrogate cancer biology and its clinical relevance. We applied mass spectrometry (MS) immunopeptidomics to investigate neoantigen presentation and whether this can be augmented through interferon gamma (IFN) or MEK-inhibitors. Methods: Four PDOs from chemotherapy refractory and one from a treatment naïve CRC were expanded to replicates with 100 million cells each, and HLA class I and class II peptide ligands were analysed by MS. Results: We identified an average of 9,936 unique peptides per PDO which compares favourably against published immunopeptidomics studies, suggesting high sensitivity. Loss of heterozygosity of the HLA locus was associated with low peptide diversity in one PDO. Peptides from genes without detectable expression by RNA-sequencing were rarely identified by MS. Only 3 out of 612 non-silent mutations encoded for neoantigens that were detected by MS. Treatment of four PDOs with IFN upregulated HLA class I expression and qualitatively changed the immunopeptidome, with increased presentation of IFN-inducible genes. HLA class II presented peptides increased on average 16-fold with IFN treatment. MEK-inhibitor treatment showed no consistent effect on class I or II HLA expression or the peptidome. Importantly, no additional HLA class I or II presented neoantigens became detectable with any treatment. Conclusions: Only 3 out of 612 non-synonymous mutations encoded for neoantigens that were detectable by MS. Although MS has sensitivity limits and biases, and likely underestimated the true neoantigen burden, this established a lower bound of the percentage of non-silent mutations that encode for presented neoantigens, which may be as low as 0.5%. This could be a reason for the poor responses of non-hypermutated CRCs to immune checkpoint inhibitors. MEK-inhibitors recently failed to improve checkpoint-inhibitor efficacy in CRC and the observed lack of HLA upregulation or improved peptide presentation may explain this.
2019-11-27 | PXD014017 | Pride
Project description:Modern antigen vaccine designs and studies of human leukocyte antigen (HLA)-mediated immune responses rely heavily on the knowledge of HLA allele-specific binding motifs and computational prediction of antigen-HLA binding affinity. Breakthroughs in HLA peptidomics have considerably expanded the databases of natural HLA antigens and enabled detailed characterizations of antigen-HLA binding specificity. However, cautions must be made when analyzing HLA peptidomics data because identified peptides may be contaminants or may weakly bind to the HLA molecules. Here, a hybrid de novo peptide sequencing approach was applied to large-scale mono-allelic HLA peptidomics datasets to uncover new antigens and refine current knowledge of HLA binding motifs. Up to 12-40% contaminations in the form of tryptic peptides were identified in the peptidomics data of HLA alleles whose binding motifs do not involve an arginine or a lysine at the C-terminus. Thousands of these peptides were reported in a community database as positive antigens and might be erroneously used to train prediction models. Furthermore, unsupervised clustering of identified antigens not only revealed additional binding motifs for several HLA class I alleles but also effectively isolated outliers which were confirmed to be false positives in a binding experiment. Overall, our findings expanded the knowledge of HLA binding specificity and indicated that a more careful HLA peptidomics data interpretation protocol is needed to ensure the high quality of community antigen databases.
2021-09-17 | PXD028088 | Pride