title: Cell-specific Cre-mediated activation of the diphtheria toxin gene in pituitary tumor cells: potential for cytotoxic gene therapy.
abstract: Diphtheria toxin has been suggested for the treatment of malignant cancer. In this paper, we describe a strategy for targeting the expression of the diphtheria toxin gene to growth hormone (GH)-producing pituitary tumor cells using adenoviral vectors. We generated adenoviral vectors in which a stuffer DNA fragment, flanked by two loxP sequences, was placed between the GH or cytomegalovirus (CMV) promoters and the diphtheria toxin gene (GH-loxP-DT, and CMV-loxP-DT) or the beta-Gal gene (GH-loxP-Gal, and CMV-loxP-Gal). Co-infection of GH-loxP-DT with either CMV-Cre or GH-Cre induced cytotoxicity that was limited to GH4 cells. Little or no cytopathic effect was seen in GH4 cells infected with control viruses (CMV-loxP-Gal or GH-loxP-Gal with CMV-Cre or GH-Cre). To test the effectiveness of this strategy in vivo, GH4 cells were transplanted into nude mice. Intratumoral co-injection of adenoviruses carrying diphtheria toxin (GH-loxP-DT, and CMV-loxP-DT) and Cre recombinase (GH-Cre, and CMV-Cre) caused rapid regression of the transplanted GH4 tumors. These results indicate that Cre-mediated activation of a loxP-repressed form of the DT gene provides a useful strategy for targeted suicide gene therapy. This approach may be useful for GH-secreting adenomas and should be applicable to other neoplastic disorders.
authors.affiliation: Division of Endocrinology, Metabolism, and Molecular Medicine, Northwestern University Medical School, Chicago, IL 60611-2908, USA.
authors.forename: Eun Jig
authors.initials: EJ
authors.lastname: Lee
authors.forename: J Larry
authors.initials: JL
authors.lastname: Jameson
mesh_terms: D000256:Adenoviridae; D000818:Animals; D016923:Cell Death / Q000235:genetics; D004167:Diphtheria Toxin / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D005822:Genetic Vectors; D013006:Growth Hormone / Q000096:biosynthesis / Q000235:genetics; D019426:Integrases / Q000235:genetics*; D051379:Mice; D008819:Mice, Nude; D008822:Mice, Transgenic; D010911:Pituitary Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D011401:Promoter Regions, Genetic; D014407:Tumor Cells, Cultured; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D004167:Diphtheria Toxin; D014764:Viral Proteins; D013006:Growth Hormone; C045073:Cre recombinase; D019426:Integrases