Antitumor immune response induced by three kinds of human leukocyte antigen-antigen/0201-restricted epitope peptides in Ewing’s sarcoma dendritic cell vaccine

PENG Wei; HUANG Xun-wu; ZHAO Wei-peng; ZHAO Ming; YANG Da-zhi

doi:10.3969/j.issn.2095-252X.2014.10.015

Abstract：Objective To compare the antitumor effects of Ewing’s sarcoma protein ( EWS ) 306, EWS 289 and EWS 401 of human leukocyte antigen ( HLA )-antigen ( A ) / 0201-restricted epitope peptides against dendritic cells ( DCs ) of Ewing’s sarcoma.Methods The peptide 9 of EWS / FLI-1 protein, which was easily combined with HLA-A / 0201 of human cell antigen was screened by Operating software of BIMAS and SYFPEITHI. And then the corresponding epitope peptide was generated. The standard 4 h-51Cr release experiment was used to test the lethal effects of cytotoxic T lymphocytes ( CTLs ) against tumor cells. Enzyme linked immunospot assay ( ELISPOT ) was applied to detect the interferon-γ ( IFN-γ ) releasing of effector cells induced by DC vaccines of epitope peptides. Accordingly, the antitumor effects in vitro were compared in an animal experiment, and all these animals received immunotherapy. Results A strong binding force with HLA-A / 0201 was noticed in the screened EWS 306, EWS 289 and EWS 401, and the generated epitope peptides were QLWQFLLEL ( EWS 306 ), ILGPTSSRL ( EWS 289 ) and SMYKYPSDI ( EWS 401 ) respectively. A high lethality was noticed in EWS 306, EWS 289 and EWS 401 groups. When the effector /target cell ratio was 50 : 1, the lethalities in EWS 306, EWS 289 and EWS 401 groups were ( 20.2±1.8 ) %, ( 12.6±0.3 ) % and ( 11.9±0.2 ) % respectively. And while in the control group, the lethality was ( 6.7±0.1 ) %. When the effector / target cell ratio was 100:1, the lethalities in EWS 306, EWS 289, EWS 401 and the control groups were ( 51.2±3.7 ) %, ( 24.6±2.1 ) %, ( 17.8±0.9 ) % and ( 7.2±0.2 ) % respectively. There were statistically signiifcant differences when the lethality between the EWS 306 group and the others was compared (P<0.05 ). The number of secreted IFN-γ in EWS 306 group was 118.3±3.6, which was obviously higher than 35.1±1.0 in EWS 401 group, 34.2±0.9 in EWS 289 group and 5.0±0.1 in the control group ( P<0.05 ). The tumor volume was ( 978.9±28.2 ) mm3 in EWS 306 group, which was obviously smaller than ( 1992.9±16.1 ) mm3 in the negative control group and ( 2001.9±12.3 ) mm3 in the blank control group. At the 35 day after inoculation, the survival rate in EWS 306 group was 80%, which was higher than 0% in the blank control group and 10% in the negative control group (P<0.05 ). At 40 day after inoculation, the survival rate in the blank control group was reduced to 0%, and 80% in EWS 306 group was obviously higher than that of the other control groups (P<0.05 ).Conclusions Stronger antitumor effects against DCs are noticed in EWS 306 when compared with that of EWS 289 and EWS 401. EWS 306 can effectively activate the lethal effects of CTLs against tumor cells and provide a new direction for the immunotherapy for Ewing's sarcoma.