title: Molecular chemotherapy of pancreatic cancer using novel mutant bacterial cytosine deaminase gene.
abstract: The combination of molecular chemotherapy with radiation therapy has the potential to become a powerful approach for treatment of pancreatic cancer. We have developed an adenoviral vector (AdbCD-D314A) encoding a mutant bacterial cytosine deaminase (bCD) gene, which converts the prodrug 5-fluorocytosine (5-FC) into the active drug 5-fluorouracil. The aim of this study was to investigate AdbCD-D314A/5-FC-mediated cytotoxicity in vitro and therapeutic efficacy in vivo alone and in combination with radiation against human pancreatic cancer cells and xenografts. AdbCD-D314A/5-FC-mediated cytotoxicity alone and in combination with radiation was analyzed using crystal violet inclusion and clonogenic survival assays. CD enzyme activity was determined by measuring conversion of [3H]5-FC to [3H]5-fluorouracil after adenoviral infection of pancreatic cancer cells in vitro and pancreatic tumor xenografts by TLC. S.c. pancreatic tumor xenografts were used to evaluate the therapeutic efficacy of AdbCD-D314A/5-FC molecular chemotherapy in combination with radiation therapy. AdbCD-D314A infection resulted in increased 5-FC-mediated pancreatic cancer cell killing that correlated with significantly enhanced CD enzyme activity compared with AdbCDwt encoding wild-type of bCD. Animal studies showed significant inhibition of growth of human pancreatic tumors treated with AdbCD-D314A/5-FC in comparison with AdbCDwt/5-FC. Also, a significantly greater inhibition of growth of Panc2.03 and MIA PaCA-2 tumor xenografts was produced by the combination of AdbCD-D314A/5-FC with radiation compared with either agent alone. The results indicate that the combination of AdbCD-D314A/5-FC molecular chemotherapy with radiation therapy significantly enhanced cytotoxicity of pancreatic cancer cells in vitro and increased therapeutic efficacy against human pancreatic tumor xenografts.
authors.affiliation: Department of Radiation Oncology, University of Alabama at Birmingham, 1530 3rd Avenue South, WTI 674, Birmingham, AL 35294-6832, USA.
authors.forename: Lyudmila N
authors.initials: LN
authors.lastname: Kaliberova
authors.forename: Debbie L
authors.initials: DL
authors.lastname: Della Manna
authors.forename: Valentina
authors.initials: V
authors.lastname: Krendelchtchikova
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Black
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Buchsbaum
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Kaliberov
mesh_terms: D000256:Adenoviridae; D019943:Amino Acid Substitution / Q000187:drug effects / Q000528:radiation effects; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000528:radiation effects; D045744:Cell Line, Tumor; D003114:Colony-Forming Units Assay; D043525:Cytosine Deaminase / Q000235:genetics* / Q000627:therapeutic use*; D004926:Escherichia coli / Q000201:enzymology*; D005260:Female; D005437:Flucytosine / Q000494:pharmacology; D015316:Genetic Therapy; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D050505:Mutant Proteins / Q000627:therapeutic use*; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000532:radiotherapy / Q000628:therapy*; D011839:Radiation, Ionizing; D023041:Xenograft Model Antitumor Assays
chemical_list: D051017:Apoptosis Regulatory Proteins; D050505:Mutant Proteins; D005437:Flucytosine; D043525:Cytosine Deaminase