Peptide FLNPDVLDI of heparanase is a novel HLA-A2-restricted CTL epitope and elicits potent immunological antitumor effects in vitro with an 8-branched design

The aim of this study was to predict and characterize a novel HLA-A2-restricted T-cell epitope of the human heparanase (HPSE) protein, as well as to evaluate its antitumor immunological effects in vitro with an 8-branched multiple antigenic peptide (MAP) design. The amino acid sequence of HPSE was scanned, and the cytotoxic T lymphocyte (CTL) epitopes were predicted using HLA-A2-restricted epitope-predictive algorithms based on supermotif and quantitative motif methods. The affinity of candidate peptides to HLA-A2 was evaluated using peptide-binding assay, by virtue of the characteristics of T2 cells. The MAPs consisting of the selected peptides were synthesized using an 8-branched design. The specific CTL-inducing ability of the MAPs was assessed by LDH release assay, and the CTL activity was evaluated by INF-γ ELISPOT assay. Among the predicted nonapeptides, the FLNPDVLDI peptide of HPSE showed the highest affinity to the HLA-A2 molecule. The 8-branched MAP comprising FLNPDVLDI induced specific CTLs for human HPSE in vitro, which effectively secreted IFN-γ and potently lysed HCC97-H human hepatocarcinoma cells and SW-480 human colonic carcinoma cells. The nonapeptide FLNPDVLDI of human HPSE appears to be a novel HLA-A2-restricted CTL epitope, and its 8-branch designed MAP is capable of inducing a potent HPSE-specific CTL response against tumor cells in vitro. Our study provides theoretical evidence for the peptide-based antitumor immunotherapy.