Generation of cytotoxic T cell responses to an HLA-A24 restricted epitope peptide derived from wild-type p53

Abstract

Mutations in the p53 gene are the most common genetic alterations found in human tumours, and these mutations result in high levels of p53 protein in the tumour cells. Since the expression levels of wild-type p53 in nonmalignant tissue are usually much lower in contrast, the p53 protein is an attractive target for cancer immunotherapy. We tested p53 encoded HLA-A24 binding peptides for their capacity to elicit anti-tumour cytotoxic T lymphocytes (CTL) in vitro. These peptides were in murine p53-derived cytotoxic peptides, which were being presented to CTL by H-2K d and H-2K b molecules, because the HLA-A24 peptide binding motifs were similar to the H-2K d and H-2K b . For CTL induction, we used CD8 + T lymphocytes from the peripheral blood mononuclear cells (PBMC) of healthy donors and the peptides from pulsed dendritic cells as antigen-presenting cells. We identified the peptide, p53-161 (AIYKQSQHM), which was capable of eliciting CTL lines that lysed tumour cells expressing HLA-A24 and p53. The effectors lysed C1RA24 cells (p53 + , HLA-A*2402 transfectant), but not their parental cell lines C1R (p53 + , HLA-A,B null cell). These results strongly indicate that the CTL exerts cytotoxic activity in HLA-A24's restricted manner. The identification of this novel p53 epitope for CTL offers the possibility to design and develop specific immunotherapeutic approaches for treating tumours with p53 mutation in HLA-A24-positive patients. © 2001 Cancer Research Campaign http://www.bjcancer.com

Toward the development of multi-epitope p53 cancer vaccines: An in vitro assessment of CD8+ T cell responses to HLA class I-restricted wild-type sequence p53 peptides

“…Enhanced expression of naturally occurring, CTLdefined wt p53 epitopes presented by HLA class I molecules on the surface of tumors relative to normal cells has been established [2][3][4][5][6][7][8][9]. Therefore, wt p53 has become a promising candidate for use in broadly applicable, off-the-shelf anti-tumor vaccines.…”

“…CD8 + T cells were positively isolated from nonadherent PBMC with immunomagnetic beads (Miltenyi Biotec, Gladbach, Germany). CD8 + T cells (2x10 6 ) and irradiated DCs (2x10 5 ) pulsed with 10μg/mL of a p53 peptide and co-cultured in wells of 24-well tissue culture plates (Becton Dickinson Labware, Franklin Lakes, NJ) in a final volume of 2mL CM/well. On day 5, 20IU/mL IL-2 was added to culture wells.…”

“…In many instances, these alterations lead to enhanced presentation of wt p53 epitopes (non-mutated peptide sequences derived from the p53 molecules expressed in tumor cells) by tumor cells for recognition by HLA class I-restricted T cells. Evidence of cellular as well as antibody-mediated anti-p53 immune responses in subjects with cancer is well documented [2][3][4][5][6][7][8][9][10], and wt p53 peptide-based vaccines have been shown in preclinical murine tumor model studies to be effective in inducing anti-tumor immunity in prevention and therapy settings [11].…”

“…To date, a number of wt p53 epitopes defined by HLA-A2 or HLA-A24-restricted, CD8 + T cell cells have been identified [2][3][4][5][6][7][8][9][10]. Some of these wt p53-derived peptides, mainly those defined by HLA-A*0201(HLA-A2)-restricted, CD8 + T cells are being clinically evaluated in cancer vaccines [12,13].…”

Harnessing the Immune System to Fight Cancer: The Promise of Genetic Cancer Vaccines

“…Widely occurring, overexpressed TAAs have been detected in different types of tumours as well as in many normal tissues, and their overexpression in tumour cells can reach the threshold for T cell recognition, breaking the immunological tolerance and triggering an anticancer response. Among the most interesting TAAs of this group are the antiapoptotic proteins (survivin) (Schmidt et al, 2003), hTERT (Vonderheide et al, 2008), and tumour suppressor proteins (e.g., p53) (Umano et al, 2001). Unique tumour antigens.…”