Combination with CD/5-FC gene therapy enhances killing of human bladder-cancer cells by radiation.
BACKGROUND
Resistance to radiation and chemotherapy is a significant obstacle to the treatment of advanced bladder cancer. Gene therapy combined with radiation represents a new approach to cancer treatment. In the present study, we investigated whether adenovirally directed, cytosine deaminase (CD)/5-fluorocytosine (5-FC) gene therapy could induce cell toxicity and radiosensitization through the intracellular production of 5-fluorouracil (5-FU) in bladder-cancer cells.


METHODS
Three human bladder-cancer cell lines, KK47 (wild-type p53+), T24 (p53 mutated) and 5637 (p53 mutated), were investigated. A recombinant adenovirus vector containing the CD gene (Ad-RSV-CD) was used. Cells were infected with Ad-RSV-CD and treated with 5-FC. Forty-eight hours after infection, the cells were irradiated and cytotoxicity assays performed to determine the extent of increase in in vitro cytotoxicity. A KK47 subcutaneous tumor-xenografts model was used in an animal study to examine the tumor growth inhibitory effect of this combination therapy. Ad-RSV-CD was directly injected into the tumor and daily 5-FC was intraperitoneally injected. Forty-eight hours after injection of Ad-RSV-CD, the tumor was irradiated. The tumor volume was measured every day.


RESULTS
In all three cell lines, the combination treatment enhanced the cell killing of human bladder-cancer cells in vitro. It also enhanced the tumor-growth inhibition in the KK47 tumor model.


CONCLUSIONS
In the present study, we demonstrated that CD/5-FC gene therapy combined with radiation therapy enhances cell killing of human bladder-cancer cells in in vitro and in vivo animal models.
Zhang
Zhujun
Z
International Center for Medical Research, Kobe University School of Medicine, 7-5-1 Kusunoki-Cho, Chuo-Ku, Kobe, Japan 650-0017.
Shirakawa
Toshiro
T
Division of Urology, Department of Organ Therapeutics, Faculty of Medicine, Kobe Graduate School of Medicine, Kobe, Japan.
Hinata
Nobuyuki
N
Division of Urology, Department of Organ Therapeutics, Faculty of Medicine, Kobe Graduate School of Medicine, Kobe, Japan.
Matsumoto
Akira
A
Radiation Biophysics and Genetics, Kobe University School of Medicine, 7-5-1 Kusunoki-Cho, Chuo-Ku, Kobe, Japan 650-0017.
Fujisawa
Masato
M
Division of Urology, Department of Organ Therapeutics, Faculty of Medicine, Kobe Graduate School of Medicine, Kobe, Japan.
Okada
Hiroshi
H
Division of Urology, Department of Organ Therapeutics, Faculty of Medicine, Kobe Graduate School of Medicine, Kobe, Japan.
Kamidono
Sadao
S
Division of Urology, Department of Organ Therapeutics, Faculty of Medicine, Kobe Graduate School of Medicine, Kobe, Japan.
Matsuo
Masafumi
M
International Center for Medical Research, Kobe University School of Medicine, 7-5-1 Kusunoki-Cho, Chuo-Ku, Kobe, Japan 650-0017.
Gotoh
Akinobu
A
International Center for Medical Research, Kobe University School of Medicine, 7-5-1 Kusunoki-Cho, Chuo-Ku, Kobe, Japan 650-0017.|Division of Urology, Department of Organ Therapeutics, Faculty of Medicine, Kobe Graduate School of Medicine, Kobe, Japan.
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D003131:Combined Modality Therapy; D043525:Cytosine Deaminase / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D005437:Flucytosine / Q000494:pharmacology*; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000532:radiotherapy / Q000628:therapy*
D005437:Flucytosine; D043525:Cytosine Deaminase