Dataset Information

Intra-patient clonal diversity in HLA class I peptide ligand presentation

ABSTRACT: Tumor heterogeneity results from clonal diversity and evolutionary selection, and is a major cause of therapeutic resistance. Immunotherapy may exploit alternative vulnerabilities of drug resistant cells, and tumor-specific HLA peptide ligands on the cell surface are promising leads to invoke such targeted anti-tumor responses. In this work, we investigate the variability in HLA class I peptide presentation between tumor cells of the same patient, as differential ligand presentation could impact the efficacy of immunological interventions. By organoid amplification, we modeled single-cell level heterogeneity in a MSI- colorectal cancer patient, and directly correlated clonal tumor proteomes with the respective ligandomes. With deep comparative proteome profiling and sensitive detection of >7000 peptide ligands from each tumor organoid line, we found tumor-surface peptide presentation to be largely uncoupled from the steady-state protein abundance. Within the small minority of tumor-specific ligands (~3%), source proteins needed for DNA damage sensing and repair, and tumor suppression were prominently featured, leading us to speculate that such peptides may be consistently presented, as degradative byproducts of intended silencing. While clone-specific differences in peptide presentation were observed, inter-clone variability was also highly prevalent (15-25%). Collectively, these illustrate the heterogeneous peptide presentation landscape even within one individual, and hint that a multi-peptide vaccination approach against highly conserved tumor suppressors may be a viable option in patients with low tumor-mutational burden.

INSTRUMENT(S): Orbitrap Fusion Lumos, Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Epithelial Cell, Colon

DISEASE(S): Colon Cancer

SUBMITTER: Laura Demmers

LAB HEAD: Wei Wu

PROVIDER: PXD016582 | Pride | 2020-10-26

REPOSITORIES: Pride

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Publications

Single-cell derived tumor organoids display diversity in HLA class I peptide presentation.

Demmers Laura C LC Kretzschmar Kai K Van Hoeck Arne A Bar-Epraïm Yotam E YE van den Toorn Henk W P HWP Koomen Mandy M van Son Gijs G van Gorp Joost J Pronk Apollo A Smakman Niels N Cuppen Edwin E Clevers Hans H Heck Albert J R AJR Wu Wei W

Nature communications 20201021 1

Tumor heterogeneity is a major cause of therapeutic resistance. Immunotherapy may exploit alternative vulnerabilities of drug-resistant cells, where tumor-specific human leukocyte antigen (HLA) peptide ligands are promising leads to invoke targeted anti-tumor responses. Here, we investigate the variability in HLA class I peptide presentation between different clonal cells of the same colorectal cancer patient, using an organoid system. While clone-specific differences in HLA peptide presentation ...[more]

PMID: 33087703

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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.

Dataset Information

Intra-patient clonal diversity in HLA class I peptide ligand presentation

Publications

Single-cell derived tumor organoids display diversity in HLA class I peptide presentation.

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