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Identification of HLA-A2-restricted CTL epitopes of a novel tumour-associated antigen, KIF20A, overexpressed in pancreatic cancer.

ABSTRACT:

Background

Identification of tumour-associated antigens (TAAs) that induce cytotoxic T lymphocytes (CTLs) specific to cancer cells is critical for the development of anticancer immunotherapy. In this study, we aimed at identifying a novel TAA of pancreatic cancer for immunotherapy.

Methods

On the basis of the genome-wide cDNA microarray analysis, we focused on KIF20A (also known as RAB6KIFL/MKlp2) as a candidate TAA in pancreatic cancer cells. The HLA-A2 (A*02:01)-restricted CTL epitopes of KIF20A were identified using HLA-A2 transgenic mice (Tgm) and the peptides were examined to check whether they could generate human CTLs exhibiting cytotoxic responses against KIF20A(+), HLA-A2(+) tumour cells in vitro.

Results

KIF20A was overexpressed in pancreatic cancer and in some other malignancies, but not in their non-cancerous counterparts and many normal adult tissues. We found that KIF20A-2 (p12-20, LLSDDDVVV), KIF20A-8 (p809-817, CIAEQYHTV), and KIF20A-28 (p284-293, AQPDTAPLPV) peptides could induce HLA-A2-restricted CTLs in HLA-A2 Tgm without causing autoimmunity. Peptide-reactive human CTLs were generated from peripheral blood mononuclear cells of HLA-A2(+) healthy donors by in vitro stimulation with the three peptides, and those CTLs successfully exhibited cytotoxic responses to cancer cells expressing both KIF20A and HLA-A2.

Conclusion

KIF20A is a novel promising candidate for anticancer immunotherapeutic target for pancreatic cancers.

SUBMITTER: Imai K

PROVIDER: S-EPMC3031900 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:OBJECTIVE: To determine the capacity of dendritic cells (DCs) loaded with single or multiple-peptide mixtures of novel hepatitis C virus (HCV) epitopes to stimulate HCV-specific cytotoxic T lymphocyte (CTL) effector functions. METHODS: A bioinformatics approach was used to predict HLA-A2-restricted HCV-specific CTL epitopes, and the predicted peptides identified from this screen were synthesized. Subsequent IFN-? ELISPOT analysis detected the stimulating function of these peptides in peripheral blood mononuclear cells (PBMCs) from both chronic and self-limited HCV infected subjects (subjects exhibiting spontaneous HCV clearance). Mature DCs, derived in vitro from CD14(+) monocytes harvested from the study subjects by incubation with appropriate cytokine cocktails, were loaded with novel peptide or epitope peptide mixtures and co-cultured with autologous T lymphocytes. Granzyme B (GrB) and IFN-? ELISPOT analysis was used to test for epitope-specific CTL responses. T-cell-derived cytokines contained in the co-cultured supernatant were detected by flow cytometry. RESULTS: We identified 7 novel HLA-A2-restricted HCV-specific CTL epitopes that increased the frequency of IFN-?-producing T cells compared to other epitopes, as assayed by measuring spot forming cells (SFCs). Two epitopes had the strongest stimulating capability in the self-limited subjects, one found in the E2 and one in the NS2 region of HCV; five epitopes had a strong stimulating capacity in both chronic and self-limited HCV infection, but were stronger in the self-limited subjects. They were distributed in E2, NS2, NS3, NS4, and NS5 regions of HCV, respectively. We also found that mDCs loaded with novel peptide mixtures could significantly increase GrB and IFN-? SFCs as compared to single peptides, especially in chronic HCV infection subjects. Additionally, we found that DCs pulsed with multiple epitope peptide mixtures induced a Th1-biased immune response. CONCLUSIONS: Seven novel and strongly stimulating HLA-A2-restricted HCV-specific CTL epitopes were identified. Furthermore, DCs loaded with multiple-epitope peptide mixtures induced epitope-specific CTLs responses.