Identification of a Novel Immunogenic HLA-A*0201-Binding Epitope of HER-2/neu with Potent Antitumor Properties

Abstract

HER-2/neu oncoprotein is overexpressed in a variety of human tumors and is associated with aggressive disease. Immunogenic HER-2/neu CTL epitopes have been used as vaccines for the treatment of HER-2/neu positive malignancies with limited success. By applying prediction algorithms for MHC class I ligands and proteosomal cleavages, in this study, we describe the identification of HER-2/neu decamer LIAHNQVRQV spanning residues 85–94 (HER-2(1085)). HER-2(1085) proved to bind with high affinity to HLA-A2.1 and was stable for 4 h in an off-kinetics assay. This peptide was immunogenic in HLA-A2.1 transgenic (HHD) mice inducing peptide-specific CTL, which responded to tumor cell lines of various origin coexpressing human HER-2/neu and HLA-A2.1. This demonstrates that HER-2(1085) is naturally processed from endogenous HER-2/neu. Five of sixteen HER-2/neu+ HLA-A2.1+ breast cancer patients analyzed had HER-2(1085)-reactive T cells ranging from 0.35–0.70% of CD8+ T cells. Depletion of T regulatory cells from PBMC enabled the rapid expansion of HLA-A2.1/HER-2(1085)pentamer+/CD8+ cells (PENT+/CD8+), whereas significantly lower numbers of CTL could be generated from unfractionated PBMC. HER-2(1085)-specific human CTL recognized the HER-2/neu+ HLA-A2.1+ tumor cell line SKBR3.A2, as determined by IFN-γ intracellular staining and in the high sensitivity CD107α degranulation assay. Finally, HER-2(1085) significantly prolonged the survival of HHD mice inoculated with the transplantable ALC.A2.1.HER tumor both in prophylactic and therapeutic settings. These data demonstrate that HER-2(1085) is an immunogenic peptide, capable of eliciting CD8-mediated responses in vitro and in vivo, providing the platform for further exploitation of HER-2(1085) as a possible target for anticancer immunotherapy.

Peptide Vaccination Breaks Tolerance to HER-2/neuby Generating Vaccine-Specific FasL+ CD4+ T Cells: First Evidence for Intratumor Apoptotic Regulatory T Cells

“…Mice were immunized thrice every 5 d by s.c. injections at the base of the tail with 100 μg of peptide in 200 μL incomplete Freund's adjuvant (IFA) along with 100 ng of granulocyte macrophage colony-stimulating factor (GM-CSF) as described (9,13).…”

“…5,8). We (9) and others (4,7,8,10,11) have shown that removal of Tregs by various means has led to generation of antitumor immunity. Thus, the observation that T cells recognizing (self) tumor antigens persist in vivo suggests that elimination through tolerance is not complete and underscores the importance of defining potent vaccines specifically activating these cells.…”

In silico Design of Discontinuous Peptides Representative of B and T-cell Epitopes from HER2-ECD as Potential Novel Cancer Peptide Vaccines

“…Also, Kastenmuller et al, 2007 identified the peptide as an epitope with the same HLA allele. In addition, Gritzapis et al, in 2008 and2010, represented HER-2/neu (657-665) and (85-94) as immunogenic epitopes of HER-2/ neu oncoprotein with potent antitumor properties. In the current study predictions failed to identify these mentioned peptides because the purpose was to predict peptides from subdomain III of HER2 ECD and one of them that was frequently selected by three and four tools used in this work.…”

“…Different studies have used distinctive methods of T-cell epitope prediction. Similar to our work, Gritzapis et al (2008;, used SYFPEITHI algorithm for T-cell epitope prediction of HER2 ECD. Based on that study they were able to introduce potent antitumor peptides.…”

Dietary Influence of the Gut Microbiome Potential Hazards and Benefits

“…The microbiome is capable of deconjugating this estrogen, and the increase in estrogen reabsorption can increase the risk of breast cancer [10]. Data suggests that CD8+ T cells are the most potent lymphocytes for killing breast cancer cells, with increased cell numbers in breast tumors correlating to better survival [13]. Data shows that CD8+ T cell activation into functional effector cells with cytotoxic properties partly depends on contact with Sphingomonas antigens in the small and large intestines [14].…”