An oncofetal antigen, IMP-3-derived long peptides induce immune responses of both helper T cells and CTLs

Abstract

Insulin-like growth factor II mRNA-binding protein 3 (IMP-3), an oncofetal antigen identified using genome-wide cDNA microarray analyses, is overexpressed in several malignancies. IMP-3-derived cytotoxic T lymphocyte (CTL) epitopes have been used for peptide-based immunotherapies against various cancers. In addition to CTLs, induction of tumor-associated antigen (TAA)-specific helper T (Th) cells is crucial for establishment of effective antitumor immunity. In this study, we aimed to identify IMP-3-derived long peptides (IMP-3-LPs) carrying CTL and promiscuous Th-cell epitopes for use in cancer immunotherapy. IMP-3-derived Th-cell epitopes that bind to multiple HLA-class II molecules were predicted by in silico analysis, and their immunogenicity was determined by utilizing human T cells. We identified two highly immunogenic IMP-3-LPs presented by multiple HLA-class II molecules. One of the IMP-3-LPs encompassed two CTL epitopes that have been used for peptide-vaccine immunotherapy in ongoing clinical trials. IMP-3-LPs-specific Th cells responded to autologous dendritic cells (DCs) loaded with the recombinant IMP-3 proteins, suggesting that these s (LPs) can be naturally processed and presented. The IMP-3-LPs and specific Th cells augmented the expansion of IMP-3-specific CTLs, which was further enhanced by programmed cell death-1 (PD-1) blockade. In addition, IMP-3-LP encapsulated in liposomes was efficiently cross-presented in vitro, and this LP successfully cross-primed CTLs in HLA-A2 transgenic mice (Tgm) in vivo. Furthermore, one of the IMP-3-LPs induced IMP-3-specific Th cells from peripheral blood mononuclear cells (PBMCs) of head-and-neck malignant tumor (HNMT) patients. These findings suggest the potential usefulness of IMP-3-LPs in propagating both Th cells and CTLs and may have implications for IMP-3-LPs-based cancer immunotherapy.

Chondroitin Sulfate-Based pH-Sensitive Polymer-Modified Liposomes for Intracellular Antigen Delivery and Induction of Cancer Immunity

“…We earlier reported an in vivo induction system of antigen-specific CTLs using antigen-loaded liposomes modified with carboxylated polyglycidols. ,, Carboxylated polyglycidols show membrane disruptive activity in response to weakly acidic pH and induce membrane fusion with endosomes after internalization to dendritic cells, resulting in the release of antigens into the cytosol of the cells. , Cytosolic release of antigens can promote MHC class I-mediated antigen presentation (cross-presentation) in both murine-derived or human-derived dendritic cells. ,, After subcutaneous administration of these liposomes to mice, antigen-specific CTLs were induced in the spleen; these CTLs migrated to tumor tissues, where they exhibited tumor-cell-killing effects. ,, However, for liposomes modified with carboxylated polyglycidols, adjuvant molecules such as monophosphoryl lipid A (MPLA) or CpG-DNA are necessary to induce strong cellular immune responses. , We further developed carboxylated polysaccharides having not only pH-responsive membrane disruptive activity but also adjuvant function. Actually, liposomes modified with 3-methylglutarylated curdlan achieved the induction of antigen-specific CTLs and a strong antitumor effect even in the absence of MPLA .…”

“…22,25 Cytosolic release of antigens can promote MHC class I-mediated antigen presentation (cross-presentation) in both murine-derived or human-derived dendritic cells. 22,26,27 After subcutaneous administration of these liposomes to mice, antigen-specific CTLs were induced in the spleen; these CTLs migrated to tumor tissues, where they exhibited tumor-cell-killing effects. 22,24,25 However, for liposomes modified with carboxylated polyglycidols, adjuvant molecules such as monophosphoryl lipid A (MPLA) or CpG-DNA are necessary to induce strong cellular immune responses.…”

Design of pH-sensitive polymer-modified liposomes for antigen delivery and their application in cancer immunotherapy

“…The combination of other cytokine or chemokine genes such as IL-12, TGF-β, or CCR7 might create various immune-inducing systems or immunosuppression cancelling systems in tumor microenvironments.Our recent and current studies have used a model antigen (chicken egg albumin, OVA), which has strong immunogenicity against mouse, for the evaluation of immune responses of pH-sensitive polymer-modified liposomes. For more practical evaluation, we have started the use of human cancer antigenic peptides such as glypican-GPC3)-derived peptide, which is overexpressed in hepatocellular carcinoma, or insulin-like growth factor II mRNA-binding protein 3 (IMP-3)-derived peptide, which is overexpressed in cases of head-and-neck malignant tumor, lung cancer, and esophageal cancer, for the evaluation of pH-sensitive polymer-modified liposomes 87,88. Actually, CHexPG-PE liposomes containing any of the respective peptides induced much more efficient cross-presentation than free peptide solution on human autologous DCs.87, These latest studies indicate clearly that our pH-sensitive polymer-modified liposomes present the potential for immune-inducing functions, not only for model antigenic proteins but also for clinically used cancer antigenic peptides.…”

Bladder cancer-associated cancer-testis antigen-derived long peptides encompassing both CTL and promiscuous HLA class II-restricted Th cell epitopes induced CD4+ T cells expressing converged T-cell receptor genes in vitro

“…Human monocyte-derived DCs and murine BM-derived DCs were generated as previously reported. [43][44][45][46][47][48] Mouse fibroblast cell lines (L cells), genetically engineered to express DR4 (DRB1 Ã 04:05, L-DR4), DR9 (DRB1 Ã 09:01, L-DR9), DR15 (DRB1 Ã 15:02, L-DR15), DR53 (DRB4 Ã 01:03, L-DR53), DP2 (DPA1 Ã 01:03/DPB1 Ã 02:01, L-DP2), DP4 (DPA1 Ã 01:03/DPB1 Ã 04:01, RM3-DP4), DP5 (DPA1 Ã 02:02/…”