Anti-tumor Activity Of HER2-specific Peptide Vaccines-CKL9 And YL20

Human epidermal growth factor receptor 2(HER2),a transmembrane receptor-like protein with tyrosine kinase activity,plays an important role in cell growth,survival and differentiation.Partial breast cancer,gastric cancer,ovarian cancer patients were found in the phenomenon of excessive expression of HER2.In recent years,a series of treatment strategies for HER2-positive cancer have been established,including passive immunotherapy(such as anti-HER2 antibody)and active immunotherapy(such as HER2-targeting peptide vaccine),there are a number of foreign HER2-based tumor peptide vaccines have started clinical trials.The sequence of tumor polypeptide vaccines for HER2 derived from epitope fragments of HER2.These vaccines,with high specificity and high safety,theoretically can induce long-lasting specific cellular and humoral immune responses,and could induce CD4 and CD8 positive T lymphocytes to immune in pre-immunized animals modelsto inhibit growth of HER2 positive tumor cells.Two polypeptide molecules CKL9 and YL20 were studied,,CKL9 with 11 amino acids was added with cysteine cyclization on the basis of the epitope fragments of HER2,while YL20 had 20 amino acids by fusing with a transmembrane peptide to improve the stability of the polypeptide and increase the ability of the epitope peptide to enter the cell.To explore whether the polypeptide vaccines CKL9 and YL20 could induce immune response and anti-tumor effect on HER-2(+)tumors in vitro and in vivo,we designed CCK-8 assay and LDH assay to test the cytotoxic T lymphocyte activity as well as the proliferative effect of CKL9 and YL20 on stimulating the mice lymphocytes,and in vivo experiments to evaluate antitumor activity of CKL9 and YL20.The lymphocytes multiplication test with CCK-8 assay indicated that incubation of CKL9 and YL20 with lymphocytes could promote lymphocyte proliferation to a certain extent.Under the concentration of 50mg·L-1peptide vaccine,the relativeproliferative rate of lymphocytes and were 11.1% with CKL9 and 16.7% with YL20respectively;the ELISPOT tests showed that IFN-γ and were 30.3 with CKL9 and 37with YL20.The cytotoxicity test with LDH assay demonstrated that the T-lymphocytes differentiation induced by polypeptide vaccine CKL9 and YL20 had lethal action effect on HER-2 positive tumor cells.With an effector-target ratio of80:1,the inhibition rate of tumor cell by cytotoxic T lymphocyte could reach 89.8%and 84.3% respectively.The experiments in vivo showed that pre-immune polypeptide CKL9 and YL20 had obvious inhibitory effect on N87 transplanted tumor cell in Balb/c mice.Thus,the polypeptide molecules CKL9 and YL20 based on HER-2 has immunogenicity to induce persistent specific CD4 and CD8 T cell immune,and inhibit the growth of HER-2 positive tumor cells.