title: Mutation of Escherichia coli cytosine deaminase significantly enhances molecular chemotherapy of human glioma.
abstract: Combined treatment using adenoviral (Ad)-directed enzyme/prodrug therapy and radiation therapy has the potential to become a powerful method of cancer therapy. We have developed an Ad vector encoding a mutant bacterial cytosine deaminase (bCD) gene (AdbCD-D314A), which has a higher affinity for cytosine than wild-type bCD (bCDwt). The purpose of this study was to evaluate cytotoxicity in vitro and therapeutic efficacy in vivo of the combination of AdbCD-D314A with the prodrug 5-fluorocytosine (5-FC) and ionizing radiation against human glioma. The present study demonstrates that AdbCD-D314A infection resulted in increased 5-FC-mediated cell killing, compared with AdbCDwt. Furthermore, a significant increase in cytotoxicity following AdbCD-D314A and radiation treatment of glioma cells in vitro was demonstrated as compared to AdbCDwt. Animal studies showed significant inhibition of subcutaneous or intracranial tumor growth of D54MG glioma xenografts by the combination of AdbCD-D314A/5-FC with ionizing radiation as compared with either agent alone, and with AdbCDwt/5-FC plus radiation. The results suggest that the combination of AdbCD-D314A/5-FC with radiation produces markedly increased cytotoxic effects in cancer cells in vitro and in vivo. These data indicate that combined treatment with this novel mutant enzyme/prodrug therapy and radiotherapy provides a promising approach for cancer therapy.
authors.affiliation: Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Kaliberov
authors.forename: J M
authors.initials: JM
authors.lastname: Market
authors.forename: G Y
authors.initials: GY
authors.lastname: Gillespie
authors.forename: V
authors.initials: V
authors.lastname: Krendelchtchikova
authors.forename: D
authors.initials: D
authors.lastname: Della Manna
authors.forename: J C
authors.initials: JC
authors.lastname: Sellers
authors.forename: L N
authors.initials: LN
authors.lastname: Kaliberova
authors.forename: M E
authors.initials: ME
authors.lastname: Black
authors.forename: D J
authors.initials: DJ
authors.lastname: Buchsbaum
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D000963:Antimetabolites / Q000627:therapeutic use; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000628:therapy*; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D003596:Cytosine / Q000378:metabolism; D043525:Cytosine Deaminase / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D005437:Flucytosine / Q000627:therapeutic use; D041722:Genes, Transgenic, Suicide; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage* / Q000235:genetics; D005910:Glioma / Q000000981:diagnostic imaging / Q000378:metabolism / Q000628:therapy*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D009368:Neoplasm Transplantation; D011355:Prodrugs / Q000627:therapeutic use; D011859:Radiography; D014183:Transplantation, Heterologous
chemical_list: D000963:Antimetabolites; D011355:Prodrugs; D003596:Cytosine; D005437:Flucytosine; D043525:Cytosine Deaminase