ABSTRACT
Tumours often evade CD8 T-cell immunity by downregulating TAP. T-cell epitopes associated with impaired peptide processing are immunogenic non-mutated neoantigens that emerge during tumour immune evasion. The preprocalcitonin (ppCT)16-25 neoepitope belongs to this category of antigens. Here we show that most human lung tumours display altered expression of TAP and frequently express ppCT self-antigen. We also show that ppCT includes HLA-A2-restricted epitopes that are processed by TAP-independent and -dependent pathways. Processing occurs in either the endoplasmic reticulum, by signal peptidase and signal peptide peptidase, or in the cytosol after release of a signal peptide precursor or retrotranslocation of a procalcitonin substrate by endoplasmic-reticulum-associated degradation. Remarkably, ppCT peptide-based immunotherapy induces efficient T-cell responses toward antigen processing and presenting machinery-impaired tumours transplanted into HLA-A*0201-transgenic mice and in NOD-scid-Il2rγnull mice adoptively transferred with human PBMC. Thus, ppCT-specific T lymphocytes are promising effectors for treatment of tumours that have escaped immune recognition.
Subject(s)
Calcitonin/metabolism , Epitopes, T-Lymphocyte/metabolism , Leukocytes, Mononuclear/metabolism , Protein Precursors/metabolism , Animals , Cell Line, Tumor , Female , HLA-A Antigens/immunology , HLA-A Antigens/metabolism , Healthy Volunteers , Humans , In Vitro Techniques , Lung Neoplasms/immunology , Lung Neoplasms/metabolism , Male , Mice , Mice, Inbred NOD , Mice, Transgenic , Tumor Escape/immunology , Tumor Escape/physiologyABSTRACT
We had previously demonstrated the role of CD103 integrin on lung tumor-infiltrating lymphocyte (TIL) clones in promoting specific TCR-mediated epithelial tumor cell cytotoxicity. However, the contribution of CD103 on intratumoral T cell distribution and functions and the prognosis significance of TIL subpopulations in non-small cell lung carcinoma (NSCLC) have thus far not been systematically addressed. In this study, we show that an enhanced CD103(+) TIL subset correlates with improved early stage NSCLC patient survival and increased intraepithelial lymphocyte infiltration. Moreover, our results indicate that CD8(+)CD103(+) TIL, freshly isolated from NSCLC specimens, display transcriptomic and phenotypic signatures characteristic of tissue-resident memory T cells and frequently express PD-1 and Tim-3 checkpoint receptors. This TIL subset also displays increased activation-induced cell death and mediates specific cytolytic activity toward autologous tumor cells upon blockade of the PD-1-PD-L1 interaction. These findings emphasize the role of CD8(+)CD103(+) tissue-resident memory T cells in promoting intratumoral CTL responses and support the rationale for using anti-PD-1 blocking Ab to reverse tumor-induced T cell exhaustion in NSCLC patients.