title: Combined cytosine deaminase expression, 5-fluorocytosine exposure, and radiotherapy increases cytotoxicity to cholangiocarcinoma cells.
abstract: Cholangiocarcinoma is a malignancy that is resistant to current therapy. We applied the toxin gene therapy strategy of cytosine deaminase conversion of the nontoxic producing 5-fluorocytosine to 5-fluorouracil combined with radiotherapy to cholangiocarcinoma. The transduction efficiency of SK-ChA-1 cholangiocarcinoma cells was determined by fluorescence-activated cell-sorting analysis following infection with recombinant adenovirus AdCMVLacZ, which encodes thc gene for Beta-galactosidase. To evaluate cytosine deaminase-mediated conversion of 5-fluorocytosine to 5-fluorouracil and subsequent cytotoxicity, SK-ChA-1 cells were infected with the recombinant adenovirus AdCMVCD, which encodes cytosine deaminase, and exposed to 5-fluorocytosine for 6 to 8 days. Additive cytotoxicity of radiation therapy was evaluated by cobalt-60 exposure following AdCMVCD infection and 5-fluorocytosine treatment. SK-ChA-1 cells were transduced (98.4%) by AdCMVLacZ at 100 plaque-forming units per cell. Following infection with AdCMVCD and exposure to 5 to 100 microgram/ml of 5-fluorocytosine, 20% to 64% of SK-ChA-1 cells were killed. A combination of radiation and cytosine deaminase/5-fluorocytosine therapy resulted in enhanced cell killing (83.5% to 91.5%). Cholangiocarcinoma cells were transduced by recombinant adenoviral vectors and were killed by cytosine deaminase-mediated production of 5-fluorouracil. Enhanced cytotoxicity was seen with the addition of external beam radiation. These results provide a foundation for multimodality therapy for human cholangiocarcinoma that combines gene therapy technology with radiation therapy.
authors.affiliation: Department of Surgery, University of Alabama at Birmingham, Birmingham AL, USA.
authors.forename: L C
authors.initials: LC
authors.lastname: Pederson
authors.forename: S M
authors.initials: SM
authors.lastname: Vickers
authors.forename: D J
authors.initials: DJ
authors.lastname: Buchsbaum
authors.forename: S R
authors.initials: SR
authors.lastname: Kancharla
authors.forename: M S
authors.initials: MS
authors.lastname: Mayo
authors.forename: D T
authors.initials: DT
authors.lastname: Curiel
authors.forename: M A
authors.initials: MA
authors.lastname: Stackhouse
mesh_terms: D000256:Adenoviridae; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology / Q000627:therapeutic use*; D001650:Bile Duct Neoplasms / Q000532:radiotherapy / Q000628:therapy*; D018281:Cholangiocarcinoma / Q000532:radiotherapy / Q000628:therapy*; D003131:Combined Modality Therapy; D043525:Cytosine Deaminase; D005437:Flucytosine / Q000378:metabolism*; D005472:Fluorouracil / Q000494:pharmacology / Q000627:therapeutic use*; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors; D006801:Humans; D009700:Nucleoside Deaminases / Q000494:pharmacology*; D011355:Prodrugs / Q000627:therapeutic use*; D011882:Radiotherapy, High-Energy; D014407:Tumor Cells, Cultured
chemical_list: D000964:Antimetabolites, Antineoplastic; D011355:Prodrugs; D005437:Flucytosine; D009700:Nucleoside Deaminases; D043525:Cytosine Deaminase; D005472:Fluorouracil