Open AccessA tumor‐specific gene therapy strategy targeting dysregulation of the VHL/HIF pathway in renal cell carcinomas
Author(s) -
Ogura Masakazu,
Shibata Toru,
Yi Junlin,
Liu Junye,
Qu Runjiang,
Harada Hiroshi,
Hiraoka Masahiro
Publication year - 2005
Publication title -
cancer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 1347-9032
DOI - 10.1111/j.1349-7006.2005.00044.x
Subject(s) - transfection , luciferase , angiogenesis , biology , cancer research , genetic enhancement , hypoxia inducible factors , hypoxia (environmental) , downregulation and upregulation , microbiology and biotechnology , reporter gene , cell growth , cell culture , gene , gene expression , chemistry , biochemistry , genetics , organic chemistry , oxygen
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 α subunit of (HIF‐α) for its oxygen‐dependent degradation. VHL mutations are found frequently in sporadic RCC. Disruption of VHL results in an abnormal accumulation of HIF‐α, 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 µg/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. ( Cancer Sci 2005; 96: 288 –294)