Gene therapy targeting for hepatocellular carcinoma: selective and enhanced suicide gene expression regulated by a hypoxia-inducible enhancer linked to a human alpha-fetoprotein promoter.
We previously reported that the retroviral vector expressing the herpes simplex virus-thymidine kinase gene under the control of 0.3-kb human alpha-fetoprotein (AFP) gene promoter (AF0.3) provided the cytotoxicity to ganciclovir (GCV) in high-AFP-producing human hepatoma cells but not in low-AFP-producing cells. Therefore, specific enhancement of AFP promoter activity is likely to be required to induce enough cytotoxicity in low-AFP-producing hepatoma cells. In this study, we constructed a hybrid promoter, [HRE]AF, in which a 0.4-kb fragment of human vascular endothelial growth factor 5'-flanking sequences containing hypoxia-responsive element (HRE) was fused to AF0.3 promoter. By means of the reporter gene transfection assay, hypoxia-inducible transcriptions that were mediated by [HRE]AF promoter were detected in low- and non-AFP-producing human hepatoma cells, but not in nonhepatoma cells. When the herpes simplex virus-thymidine kinase gene controlled by [HRE]AF promoter was transduced into hepatoma and nonhepatoma cells by a retroviral vector, the exposure to 1% O2 induced GCV cytotoxicity specifically in the hepatoma cells. Moreover, in nude mice bearing solid tumor xenografts, only the tumors consisting of the virus-infected hepatoma cells gradually disappeared by GCV administration. These results indicate that the hypoxia-inducible enhancer of the human vascular endothelial growth factor gene, which is directly linked to human AFP promoter, involves selective and enhanced tumoricidal activity in gene therapy for hepatocellular carcinoma.
Ido
A
A
Department of Internal Medicine II, Miyazaki Medical College, Kiyotake, Japan.
Uto
H
H
Moriuchi
A
A
Nagata
K
K
Onaga
Y
Y
Onaga
M
M
Hori
T
T
Hirono
S
S
Hayashi
K
K
Tamaoki
T
T
Tsubouchi
H
H
D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000276:immunology / Q000628:therapy*; D015687:Cell Hypoxia / Q000235:genetics; D016228:Endothelial Growth Factors / Q000235:genetics; D004742:Enhancer Elements, Genetic; D015774:Ganciclovir / Q000633:toxicity; D015972:Gene Expression Regulation, Neoplastic; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000276:immunology / Q000628:therapy*; D008222:Lymphokines / Q000235:genetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D011401:Promoter Regions, Genetic; D012190:Retroviridae / Q000235:genetics; D018139:Simplexvirus / Q000201:enzymology / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D014161:Transduction, Genetic; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000509:alpha-Fetoproteins / Q000096:biosynthesis / Q000235:genetics*
D016228:Endothelial Growth Factors; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000509:alpha-Fetoproteins; D013937:Thymidine Kinase; D015774:Ganciclovir