Serine Proteases Enhance Immunogenic Antigen Presentation on Lung Cancer Cells

Abstract

Immunotherapies targeting immune checkpoints have proven efficacious in reducing the burden of lung cancer in patients; however, the antigenic targets of these re-invigorated T cells remain poorly defined. Lung cancer tumors contain tumor-associated macrophages (TAM) and neutrophils, which release the serine proteases neutrophil elastase (NE) and proteinase 3 (P3) into the tumor microenvironment. NE and P3 shape the antitumor adaptive immune response in breast cancer and melanoma. In this report, we demonstrate that lung cancer cells cross-presented the tumor-associated antigen PR1, derived from NE and P3. Additionally, NE and P3 enhanced the expression of human leukocyte antigen (HLA) class I molecules on lung cancer cells and induced unique, endogenous peptides in the immunopeptidome, as detected with mass spectrometry sequencing. Lung cancer patient tissues with high intratumoral TAM were enriched for MHC class I genes and T-cell markers, and patients with high TAM and cytotoxic T lymphocyte (CTL) infiltration had improved overall survival. We confirmed the immunogenicity of unique, endogenous peptides with cytotoxicity assays against lung cancer cell lines, using CTL from healthy donors that had been expanded against select peptides. Finally, CTL specific for serine proteases–induced endogenous peptides were detected in lung cancer patients using peptide/HLA-A2 tetramers and were elevated in tumor-infiltrating lymphocytes. Thus, serine proteases in the tumor microenvironment of lung cancers promote the presentation of HLA class I immunogenic peptides that are expressed by lung cancer cells, thereby increasing the antigen repertoire that can be targeted in lung cancer.

Targeting the Leukemia Antigen PR1 with Immunotherapy for the Treatment of Multiple Myeloma

“…Furthermore, we note that fine epitope mapping demonstrated that 8F4 has contact residues with the HLA-A2 molecule (13). As HLA-A2 is part of the conformational epitope of PR1/ HLA-A2, naturally we expect some binding of 8F4 to HLA-A2, as shown previously (14,15,19). However, to date, preclinical studies (13,26) and clinical trials (11,32) have demonstrated PR1-targeting immunotherapies to be safe and efficacious despite the shared expression of NE and P3 between malignant cells and normal counterpart, and the binding of 8F4 to HLA-A2.…”

“…S2). Previously, we demonstrated that solid tumor cells can cross-present PR1 from both soluble and cell-associated sources of NE and P3 (14,19). These findings were recapitulated in the U266 multiple myeloma cells that were cocultured with soluble NE, P3, or irradiated HLA-A2 À PMNs, the latter serving as the cellular source of NE and P3 that lack endogenous PR1 ( Fig.…”

“…In addition to myeloid leukemia, published reports have shown that nonmyeloid tumors lacking endogenous P3 and NE expression (i.e., lack PR1) are able to take up NE and P3 from the extracellular environment (14)(15)(16)(17)(18). Furthermore, we showed that breast cancer, melanoma, lung cancer, and malignant lymphoid cells cross-present NE and P3 (i.e., present PR1 on surface HLA-A2), and are rendered susceptible to PR1-CTL and 8F4 (14,15,19). Cross-presentation is a mechanism predominantly found in antigen-presenting cells (APC), whereby exogenous antigens are taken up, processed, and presented on HLA class I to prime an immune response (20).…”

“…kits from Invitrogen. Cross-presentation of peptides was detected by staining cell surface with fluorescently conjugated, anti-PR1/HLA-A2 antibody (clone 8F4) as previously described (14,15,19). Costimulatory molecule surface expression was analyzed by staining myeloma patient bone marrow for CD19, CD33, CD34, CD38, CD138, CD40, CD80, CD86, and HLA-DR (all from Biolegend).…”

Low P4HA2 and high PRTN3 expression predicts poor survival in patients with pancreatic cancer

“…Moreover, it has been found that PRTN3 induces phosphorylation and nuclear translocation of p44/ p42 and JNK1, leading to cancer cell motility, through a nonproteolytic way [19]. Notably, recent studies revealed that PRTN3 expressed by neutrophils within the TME can be taken up by breast cancer and melanoma cells, which in turn increase the susceptibility to PR1-targeting therapies [14,20].…”