Ionizing radiation increases adenovirus uptake and improves transgene expression in intrahepatic colon cancer xenografts.
Specific targeting and transgene expression in tumors are critical in adenovirus gene therapy for intrahepatic colon carcinoma metastases. In this study, we investigated if ionizing radiation could increase adenoviral uptake by cells. Various human cell lines and rat hepatocytes were irradiated prior to exposure to a cytomegalovirus (CMV) promoter-driven green fluorescent protein (GFP) marker gene adenoviral vector. We found that gamma-radiation increased the number of GFP-positive cells in a dose- and time-dependent manner for most cells, ranging from 4.6- to 27.1-fold after a 4-Gy treatment. No induction occurred for lentiviral vector, lipofection, or naked plasmid exposure. Preincubation of cells with adenovirus failed to show an increase, suggesting that radiation might mediate adenoviral infection by inducing viral uptake into cells. We demonstrated that radiation induced internalization of a fluorescence-labeled adenovirus (Cy3-Ad) and an increase in intracellular viral DNA content. Rats bearing intrahepatic colon carcinoma xenografts were irradiated in the tumor region followed by portal venous administration of an adenoviral vector containing a CMV-beta-galactosidase (beta-gal) gene. Radiation increased beta-gal activity in tumors as much as 5.4-fold after a 25-Gy treatment. These data suggest that a combination of regional radiation treatment with adenovirus gene therapy is a rational strategy for improving adenoviral targeting and transgene expression in tumors.
Zhang
Ming
M
Department of Radiation Oncology, Ann Arbor, Michigan 48109-0582, USA. mingz@med.umich.edu
Li
Shengping
S
Li
Jun
J
Ensminger
William D
WD
Lawrence
Theodore S
TS
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000473:pathology* / Q000628:therapy*; D003587:Cytomegalovirus / Q000235:genetics; D043525:Cytosine Deaminase / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D049452:Green Fluorescent Proteins; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000628:therapy; D011401:Promoter Regions, Genetic; D011839:Radiation, Ionizing; D051381:Rats; D013997:Time Factors; D019076:Transgenes; D001616:beta-Galactosidase / Q000378:metabolism
D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D001616:beta-Galactosidase; D043525:Cytosine Deaminase