XAGE-1b Cancer/Testis Antigen Is a Potential Target for Immunotherapy in Prostate Cancer

Abstract

Introduction: Gene-modified cell vaccines are now considered to be the best way to achieve immunotherapy for a variety of cancers including prostate cancer (PCa). XAGE-1b is a member of the cancer/testis antigen family which has demonstrated strong immunogenicity. We investigated whether XAGE-1b is an ideal target for PCa immunotherapy. Materials and Methods: The recombinant eukaryotic expression vector pDisplay-XAGE-1b was constructed. Then the recombinant vector was transfected into Myc-CaP cells and its immunogenicity in vitro was studied. After transfection, the Myc-CaP-XAGE-1b cells were injected into FVB mice subcutaneously. Tumor growth was periodically observed and the anti-tumor effect and mechanism in vivo were further studied. Results: The recombinant vector was correctly constructed by DNA sequencing and restriction endonuclease digestion. Myc-CaP cells were successfully transfected with XAGE-1b gene by immunofluorescence staining and Western blot. The transfected cells exhibited increased IFN-γ secretion, decreased IL-6 secretion and enhanced killing activity. Tumor grew slower in XAGE-1b-modified FVB mice than in wild-type FVB mice. High dendritic cell expression and low myeloid-derived suppressor cell expression were observed in tumor tissues expressed with XAGE-1b. Conclusions: XAGE-1b gene transfection could significantly enhance the immunogenicity of Myc-CaP cells. Therefore, XAGE-1b may be an attractive target for antigen-specific immunotherapy in PCa.