title: Comparison of antigen expression from plasmid DNA in tumor-free and antigen-expressing tumor-bearing mice.
abstract: Reduced antigen expression after DNA vaccination could be a factor that limits its therapeutic effects in antigen-expressing tumor-bearing hosts. To examine whether the presence of an antigen-positive tumor results in the destroy of antigen-expressing cells, pCMV-OVA plasmid expressing ovalbumin (OVA), a model antigen, was intradermaly injected to tumor-free mice and those bearing an EG7-OVA tumor, which stably expresses OVA. For a quantitative evaluation of the elimination of antigen-expressing cells, a plasmid independently expressing firefly luciferase and OVA (pCMV-Luc/OVA) was injected to mice that had been untreated or administered with pCMV-OVA, and luciferase activity was measured one week after the administration. In both tumor-free and tumor-bearing mice, a pre-injection of pCMV-OVA reduced the luciferase expression from pCMV-OVA/Luc compared with a pre-injection of an empty plasmid, suggesting that an immune response to antigen-expressing cells is induced. In tumor-bearing mice, OVA-specific humoral and cellular immune responses were detected even before the vaccination, but such responses had no significant effects on the luciferase expression from pCMV-OVA/Luc. These results indicate that DNA vaccination can induce antigen-specific immune response even in tumor-bearing mice, although it is not strong enough to reject the tumor burden.
authors.affiliation: Department of Biopharmaceutics and Drug Metabolism, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan.
authors.forename: Xin
authors.initials: X
authors.lastname: Guan
authors.forename: Xin
authors.initials: X
authors.lastname: Guan
authors.forename: Makiya
authors.initials: M
authors.lastname: Nishikawa
authors.forename: Makiya
authors.initials: M
authors.lastname: Nishikawa
authors.forename: Hisoon
authors.initials: H
authors.lastname: Li
authors.forename: Hisoon
authors.initials: H
authors.lastname: Li
authors.forename: Takahashi
authors.initials: T
authors.lastname: Rei
authors.forename: Takahashi
authors.initials: T
authors.lastname: Rei
authors.forename: Yuki
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Yuki
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Takakura
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Takakura
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D003587:Cytomegalovirus / Q000235:genetics / Q000472:pathogenicity; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D009374:Neoplasms, Experimental / Q000276:immunology*; D010047:Ovalbumin / Q000235:genetics / Q000276:immunology*; D010957:Plasmids / Q000235:genetics* / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology*
chemical_list: D000951:Antigens, Neoplasm; D019444:Vaccines, DNA; D010047:Ovalbumin