Gene transfer into human prostate adenocarcinoma cells with an adenoviral vector: Hyperthermia enhances a double suicide gene expression, cytotoxicity and radiotoxicity.
We have previously developed a recombinant adenovirus containing a fusion gene of Escherichia coli cytosine deaminase (CD) and herpes simplex virus type 1 thymidine kinase (HSV-1 TK) controlled by a cytomegalovirus (CMV) enhancer-promoter. This replication-incompetent adenovirus effectively transduced the CD-TK gene into human prostate adenocarcinoma DU-145 or PC-3 cells. Interestingly, heat shock at 41 degrees C for 4 hours elevated the level of CD-TK by approximately 5- to 20-fold at a multiplicity of infection (MOI) of 1. Heat-enhanced expression of CD-TK promoted cytotoxicity by 23-, 9-, or 47-fold in the presence of 50 microg/mL ganciclovir (GCV), 500 microg/mL 5-fluorocytosine (5-FC), or 50 microg/mL GCV+500 microg/mL 5-FC, respectively, at an MOI of 1. Moreover, there was an increase in radiosensitivity when adenovirus-infected cells were heated at 41 degrees C for 4 hours followed by irradiation in the presence of the prodrugs. Virus+heat+1 microg/mL GCV treatment increased radiosensitivity by a dose-modifying factor (DMF) of 2.2, whereas virus+heat+10 microg/mL 5-FC exposure resulted in a DMF of 2.3. Radiosensitization was clearly enhanced as a result of combined prodrug exposure (DMF=4.4). Our results suggest that the efficiency in expression of suicide genes from an adenoviral vector used for cytotoxic anticancer therapy could be improved by combining heat treatment with radiation therapy.
Lee
Yong J
YJ
Department of Pharmacology and Cancer Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA. leeyj@msx.upmc.edu
Lee
Heurian
H
Borrelli
Michael J
MJ
D000230:Adenocarcinoma / Q000235:genetics / Q000628:therapy*; D000256:Adenoviridae / Q000235:genetics*; D000998:Antiviral Agents / Q000627:therapeutic use*; D002470:Cell Survival; D043525:Cytosine Deaminase; D004357:Drug Synergism; D005437:Flucytosine / Q000627:therapeutic use; D015774:Ganciclovir / Q000627:therapeutic use; D015870:Gene Expression; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D018259:Herpesvirus 1, Human / Q000201:enzymology; D006801:Humans; D006979:Hyperthermia, Induced; D008297:Male; D009700:Nucleoside Deaminases / Q000235:genetics; D011471:Prostatic Neoplasms / Q000235:genetics / Q000628:therapy*; D011878:Radiotherapy; D011993:Recombinant Fusion Proteins / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism
D000998:Antiviral Agents; D011993:Recombinant Fusion Proteins; D005437:Flucytosine; D013937:Thymidine Kinase; D009700:Nucleoside Deaminases; D043525:Cytosine Deaminase; D015774:Ganciclovir