A tumor-specific gene therapy strategy targeting dysregulation of the VHL/HIF pathway in renal cell carcinomas.
Hypoxia-inducible factors, key transcription factors for hypoxia-dependent gene expression, play important roles in angiogenesis and tumor growth. The VHL protein binds to the alpha subunit of (HIF-alpha) for its oxygen-dependent degradation. VHL mutations are found frequently in sporadic RCC. Disruption of VHL results in an abnormal accumulation of HIF-alpha, leading to the upregulation of downstream genes such as the vascular endothelial growth factor gene. We constructed a luciferase reporter vector driven by hypoxia-responsive elements (5HRE/luc) and a therapeutic vector expressing a herpes simplex virus thymidine kinase gene (5HRE/tk). In the transient transfection assay using VHL-deficient 786-O cells, constitutive luciferase expression was detected under both aerobic and hypoxic conditions. In contrast, 786-O cells transfected with a wild-type VHL showed hypoxia-inducible luciferase activity. In in vitro MTS assay, 50% of growth inhibition of 786-O cells stably transfected with 5HRE/tk was achieved with exposure to 0.2 microg/mL of GCV under both aerobic and hypoxic conditions. Xenografts of the stable clone in SCID mice exhibited a marked regression on daily injections of GCV (50 mg/kg) for 10 days. In conclusion, a hypoxia-responsive vector may have therapeutic potential for RCC with VHL mutations.
Ogura
Masakazu
M
Department of Therapeutic Radiology and Oncology, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan.
Shibata
Toru
T
Yi
Junlin
J
Liu
Junye
J
Qu
Runjiang
R
Harada
Hiroshi
H
Hiraoka
Masahiro
M
D000818:Animals; D002292:Carcinoma, Renal Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000628:therapy*; D045744:Cell Line, Tumor; D017930:Genes, Reporter / Q000235:genetics; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D051379:Mice; D016513:Mice, SCID; D009154:Mutation / Q000235:genetics; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D013379:Substrate Specificity; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
D021122:Protein Subunits; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D013937:Thymidine Kinase