In vivo immunogenic characteristics of cytotoxic T lymphocyte epitopes from pancreatic tumor antigen MUC4 / 中国病理生理杂志

AIM:Peptide vaccines have been conceived as promising therapies for tumor-inflicted patients due to their easy production and capability of inducing specific immune response required for defending the tumor.During our previous research,4 HLA-A2-restricted peptides had been identified as immunogenic in vivo.In this study, we aimed to testify the in vivo immunogenicity of the 4 peptides.METHODS: BALB/c mice were vaccinated with HLA-A2 restricted peptides emulsified in incomplete Freund's adjuvant(IFA)subcutaneously in combination with the epitope at the adjacent location.After the 3rd peptide vaccination for 10 d,the peptide-specific immune response was evaluated by ELISPOT and ELISA.The ability to induce T cell response was investigated by using cytotoxicity assay in vivo and the presence of pep-tide-specific CD8+T cells capable of recognizing the MHC-peptide was detected by flow cytometry.RESULTS: Among the 4 candidate HLA-A2 restricted peptides,the immune response elicited by P2004-1Y9V was superior to that of the other 3 peptides.The CTLs induced by P2004 and P2004-1Y9V lysed CAPAN-2 cells.P2004-1Y9V peptide-specific CTLs showed higher cytotoxicity against pancreatic tumor cell lines of CAPAN-2 than the native peptide-specific CTLs.Intracellu-lar cytokine staining assay indicated the presence of P 2004-1Y9V specific CD8 +T cells in the P2004-1Y9V vaccinated mice.CONCLUSION:P2004-1Y9V is the most immunogenic peptide in vivo, and can be explored as potential tumor peptide vaccine in the future clinical study.

Identification and molecular modification of cytotoxic T-lymphocyte epitopes from osteosarcoma high-expressing antigen PBF / 中国病理生理杂志

AIM:To observe whether modified epitopes from osteosarcoma high-expressing antigen papilloma-virus-binding factor (PBF) have HLA-A2 restricted antitumor ability,and to develop peptide-based immunotherapy for os-teosarcoma. METHODS:RT-PCR and Western blot were used to determine the expression of PBF in the osteosarcoma cell lines U2OS and Saos-2. HLA-A2 epitopes from PBF protein were predicted by NetCTL 1.2, SYFPEITHI and IEDB. The modified peptides from PBF containing HLA-A2 binding anchor motifs were designed by replacing the anchor residues. The peptides were synthesized by standard solid-phase methods,and the binding affinity of the peptides to HLA-A?0201 was evaluated by T2A2 cell binding assay. ELISPOT assay was used to investigate the seretion of interferon-γ(IFN-γ) from the peptide-induced specific cytotoxic T-lymphocytes (CTLs). The ability of inducing T-cell response was analyzed by lactate dehydrogenase (LDH) release assay and carboxyfluorescein succinimidyl ester (CFSE) cytotoxicity assay in vitro. RE-SULTS:The expression of PBF was observed in the U2OS and Saos-2 cells. The candidate peptides P75-1Y2L,P412-1Y, P416-1Y2L9V, P107-1Y and P435-1Y2L showed moderate affinity toward HLA-A2 molecule. The modified peptides showed significantly higher affinity with HLA-A2 than the native peptide. ELISPOT assay showed that P412, P412-1Y, P416,P416-1Y2L9V and P435-1Y2L induced specific CTLs to secrete IFN-γ, and P412-1Y and P416-1Y2L9V induced more secretion of IFN-γ than the native peptide. The CTLs induced by P412, P412-1Y, P416 and P416-1Y2L9V lysed U2OS cells. P412-1Y and P416-1Y2L9V peptide-specific CTLs showed higher cytotoxicity against U2OS cells than the native peptide-specific CTLs. CONCLUSION:Compared with the native peptide,modified epitopes P412-1Y and P416-1Y2L9V have higher binding affinity with HLA-A?0201 and retain immunogenecity. In addition,the anti-tumor immunity effects of modified epitopes P412-1Y and P416-1Y2L9V are stronger than the native peptide. The peptides P412-1Y and P416-1Y2L9V is excellent HLA-A?0201 restricted CTL epitopes from tumor antigen PBF,which could serve as new can-didates towards antitumor peptide vaccines.

Reversal of adriamycin resistance by digoxin in human breast cancer cell line MCF-7/adriamycin and its mechanism / 生理学报

The aim of this study was to investigate the effects of digoxin on the chemoresistance of human breast cancer cell line MCF-7/adriamycin (ADR) and its underlying mechanism. MCF-7 and MCF-7/ADR cells were designated as control and ADR groups, respectively. MCF-7/ADR cells in ADR + digoxin group received 48 h of digoxin (10 nmol/L) treatment; MCF-7/ADR cells transfected with pLKO.1-shHIF-1α and pLKO.1-shcontrol plasmids were named shHIF-1α and shcontrol groups, respectively. CCK-8 assay was employed to detect the cytotoxic effect of ADR on MCF-7/ADR cells, and IC50 value and resistance index were calculated according to CCK-8. RT-PCR was used to measure the mRNA levels of hypoxia inducible factor-1α (HIF-1α) and multidrug resistance-1 (MDR1). Western blot was used to analyze the protein levels of HIF-1α and MDR1. Flow cytometry was used to determine the apoptosis. The result showed that the resistance index of MCF-7/ADR cells was 115.6, and it was reduced to 47.2 under the action of digoxin (P < 0.05). In comparison with control group, ADR groups showed increased protein and mRNA levels of HIF-1α and MDR1 (P < 0.05). Digoxin reduced the protein levels of HIF-1α and MDR1, as well as the mRNA level of MDR1, but did not affect the mRNA level of HIF-1α. After HIF-1α gene was silenced, the protein levels of HIF-1α and MDR1 were down-regulated (P < 0.05), and the pro-apoptotic effect of ADR on MCF-7/ADR cells was enhanced. Although it was also observed that digoxin promoted cell apoptosis in both shcontrol and shHIF-1α groups, the difference between the two groups was not significant. In conclusion, the results suggest that digoxin may partially reverse the ADR resistance in human breast cancer cell line MCF-7/ADR by means of down-regulating the expression levels of HIF-1α and MDR1 and promoting apoptosis via HIF-1α-independent pathway.

Reversal of resistance to adriamycin in human breast cancer cell line MCF-7/ADM by silencing AEG-1 gene and its mechanism / 生理学报

The aim of this study was to investigate the effects of AEG-1 gene silencing on the chemoresistance of human breast cancer cell line MCF-7/ADM and its possible mechanism. MCF-7/ADM cells were incubated in the medium containing adriamycin (ADM). The recombinant pLKO.1-shAEG-1 plasmid was constructed to silence AEG-1 expression in human breast cancer MCF-7/ADM cells. MTT assay was employed to detect the anti-tumor effect of ADM on MCF-7/ADM cells, and IC50 value of ADM was calculated according to MTT. Flow cytometry was used to determine the apoptosis. Western blot was used to analyze the expression levels of AEG-1, p-Akt, p-MDM2, p-Bad, p53 and MDR1. The result showed MCF-7/ADM had a significantly higher expression level of AEG-1 compared with that of MCF-7 (P < 0.05), however, the expression of AEG-1 was decreased after AEG-1 gene silencing. The IC50 value of ADM in shAEG-1 group was significantly lower than that in shcontrol group. AEG-1 gene silencing induced cell apoptosis and enhanced the pro-apoptotic effect of ADM on MCF-7/ADM cells. After AEG-1 gene silencing, the phosphorylation of Akt, MDM2 and Bad was inhibited (P < 0.05), the protein levels of p53 and MDR1 were up-regulated (P < 0.05) and down-regulated (P < 0.05) respectively, compared with control. In conclusion, the results suggest that AEG-1 gene silencing can reverse the ADM resistance in human breast cancer cell line MCF-7/ADM by means of inducing apoptosis and down-regulating the protein level of MDR1.