title: Gene therapy vectors containing CArG elements from the Egr1 gene are activated by neutron irradiation, cisplatin and doxorubicin.
abstract: Combining gene therapy with radiotherapy and chemotherapy holds potential to increase the efficacy of cancer treatment, while minimizing side effects. We tested the responsiveness of synthetic gene promoters containing CArG elements from the Early Growth Response 1 (Egr1) gene after neutron irradiation, doxorubicin and cisplatin. Human MCF-7 breast adenocarcinoma and U373-MG glioblastoma cells were transfected with plasmids containing CArG promoters controlling the expression of the green fluorescent protein (GFP). Exposing the cells to neutrons, doxorubicin or cisplatin resulted in a significant induction of transgene expression. Therapeutic advantage was demonstrated by replacing the reporter with the herpes simplex virus thymidine kinase (HSVtk), able to convert the prodrug ganciclovir (GCV) into a cytotoxin. A 1.3 Gy neutron dose caused 49% growth inhibition in MCF-7 cells, which increased to 63% in irradiated CArG-HSVtk-transfectants treated with GCV. Exposure to 0.5 microM cisplatin or 0.01 microM doxorubicin induced a growth inhibition of 25-30% in MCF-7 cells. In the presence of GCV, this value increased to 65-70% in cells transfected with the CArG promoter constructs driving the expression of HSVtk. These data indicate that combining CArG-mediated HSVtk/GCV suicide gene therapy with radio- and chemotherapy can enhance antitumor toxicity, and validates future in vivo investigations.
authors.affiliation: Department of Radiation Oncology, Wayne State University, Detroit, Michigan, USA.
authors.forename: Olga
authors.initials: O
authors.lastname: Greco
authors.forename: Tanya M
authors.initials: TM
authors.lastname: Powell
authors.forename: Brian
authors.initials: B
authors.lastname: Marples
authors.forename: Michael C
authors.initials: MC
authors.lastname: Joiner
authors.forename: Simon D
authors.initials: SD
authors.lastname: Scott
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000532:radiotherapy / Q000628:therapy; D000970:Antineoplastic Agents / Q000494:pharmacology*; D000998:Antiviral Agents / Q000627:therapeutic use; D017209:Apoptosis; D001932:Brain Neoplasms / Q000188:drug therapy / Q000532:radiotherapy / Q000628:therapy*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000532:radiotherapy / Q000628:therapy*; D002945:Cisplatin / Q000494:pharmacology; D003131:Combined Modality Therapy; D004268:DNA-Binding Proteins / Q000235:genetics*; D004317:Doxorubicin / Q000494:pharmacology; D051766:Early Growth Response Protein 1; D015774:Ganciclovir / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D005909:Glioblastoma / Q000188:drug therapy / Q000532:radiotherapy / Q000628:therapy; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics*; D009502:Neutrons; D011401:Promoter Regions, Genetic; D011838:Radiation-Sensitizing Agents / Q000627:therapeutic use; D020218:Response Elements / Q000235:genetics; D018139:Simplexvirus / Q000201:enzymology / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics*; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers
chemical_list: D000970:Antineoplastic Agents; D000998:Antiviral Agents; D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D017874:Immediate-Early Proteins; D011838:Radiation-Sensitizing Agents; D014157:Transcription Factors; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D004317:Doxorubicin; D013937:Thymidine Kinase; D015774:Ganciclovir; D002945:Cisplatin