title: Electroporation-mediated and EBV LMP1-regulated gene therapy in a syngenic mouse tumor model.
abstract: Latent membrane protein 1 (LMP1) is an Epstein-Barr virus (EBV)-encoded oncogene expressed in EBV-associated nasopharyngeal carcinoma (NPC). Previous studies indicate that a strategy combining LMP1-mediated NF-kappaB activation and the HSV thymidine kinase/Ganciclovir (HSVtk/GCV) prodrug system leads to regression of tumor growth in nude mice. To improve the efficacy of this strategy in immunocompetent hosts, we developed a therapeutic cassette, p6kappaB-EDL1E-tk, containing six copies of the NF-kappaB binding motif and an epithelial-specific EBV promoter, ED-L1E. The cassette was tested in a murine CT-26 carcinoma model in syngenic Balb/c mice. Coinjection of an LMP1-expressing vector and p6kappaB-EDL1E-tk by in vivo electroporation in mouse muscle revealed at least two-fold higher TK enzymatic activity than that of previously tested pLTR-tk. Furthermore, growth was attenuated in a group of mice containing LMP1-positive tumors that were intratumorally injected with the p6kappaB-EDL1E-tk cassette and GCV via in vivo electroporation, but not in mice treated with p6kappaB-EDL1E-tk or GCV alone. Similarly, no retardation of tumor growth was observed in mice containing LMP1-negative CT-26 tumors injected with both the p6kappaB-EDL1E-tk cassette and GCV. We propose that intratumoral injection of therapeutic agents, such as DNA of transcription-regulated cassette and GCV, via in vivo electroporation may be used as an alternative treatment for EBV LMP1-expressing cancers.
authors.affiliation: Institute of Microbiology and Immunology, National Yang-Ming University, Shih-pai, Taipei 112, Republic of China. ysc@mail.cgu.edu.tw
authors.forename: Yu-hua
authors.initials: YH
authors.lastname: Hsieh
authors.forename: Chang-jer
authors.initials: CJ
authors.lastname: Wu
authors.forename: Kai-ping
authors.initials: KP
authors.lastname: Chow
authors.forename: Chia-lung
authors.initials: CL
authors.lastname: Tsai
authors.forename: Yu-sun
authors.initials: YS
authors.lastname: Chang
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D018274:Electroporation; D015774:Ganciclovir / Q000494:pharmacology; D018390:Gene Targeting; D015316:Genetic Therapy; D008156:Luciferases; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D016328:NF-kappa B / Q000378:metabolism; D014158:Transcription, Genetic; D014763:Viral Matrix Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C037662:EBV-associated membrane antigen, Epstein-Barr virus; D016328:NF-kappa B; D014763:Viral Matrix Proteins; D008156:Luciferases; D015774:Ganciclovir