title: Sensitisation of human carcinoma cells to the prodrug CB1954 by adenovirus vector-mediated expression of E. coli nitroreductase.
abstract: The enzyme nitroreductase from E. coli can reduce the weak, monofunctional alkylating agent 5-(aziridin-1-yl)-2, 4-dinitrobenzamide (CB1954) to a potent cytotoxic species that generates interstrand crosslinks in DNA. Nitroreductase therefore has potential as a "suicide enzyme" for cancer gene therapy, as cells that express nitroreductase become selectively sensitive to the prodrug CB1954. We have incorporated a nitroreductase expression cassette into a replication-defective adenovirus vector (Ad-CMV-ntr), which allowed efficient gene transfer to SK-OV-3 or IGROV-1 ovarian carcinoma cells. Nitroreductase levels increased in line with multiplicity of infection, and this was reflected in increasing sensitisation of the cells to CB1954, reaching an optimum (approx. 2, 000-fold sensitisation) with 25-50 p.f.u. per cell. Similar Ad-CMV-ntr-dependent sensitisation to CB1954 was seen in 3 of 6 low-passage primary ovarian tumour lines. Cells grown at low-serum concentration to inhibit proliferation remained equally susceptible to the Ad-CMV-ntr-dependent cytotoxicity of CB1954, indicating a distinct advantage over retroviral gene delivery and other popular enzyme-prodrug systems for human tumours with a low rate of cell proliferation. Additionally, cisplatin-resistant cells were sensitised towards CB1954 by Ad-CMV-ntr as efficiently as the parental cells, indicating that the system could be effective in patients with cisplatin-resistant tumours. In a murine xenograft model for disseminated peritoneal carcinomatosis with ascites, treatment of nude mice bearing intraperitoneal SUIT2 tumours with Ad-CMV-ntr and CB1954 almost doubled the median survival from 14 to 26 days (p < 0.0001).
authors.affiliation: The University of Birmingham CRC Institute for Cancer Studies, Edgbaston, Birmingham, United Kingdom.
authors.forename: S J
authors.initials: SJ
authors.lastname: Weedon
authors.forename: N K
authors.initials: NK
authors.lastname: Green
authors.forename: I A
authors.initials: IA
authors.lastname: McNeish
authors.forename: M G
authors.initials: MG
authors.lastname: Gilligan
authors.forename: V
authors.initials: V
authors.lastname: Mautner
authors.forename: C J
authors.initials: CJ
authors.lastname: Wrighton
authors.forename: A
authors.initials: A
authors.lastname: Mountain
authors.forename: L S
authors.initials: LS
authors.lastname: Young
authors.forename: D J
authors.initials: DJ
authors.lastname: Kerr
authors.forename: P F
authors.initials: PF
authors.lastname: Searle
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001388:Aziridines / Q000494:pharmacology*; D002277:Carcinoma / Q000188:drug therapy*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology*; D005260:Female; D005822:Genetic Vectors; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009601:Nitroreductases / Q000096:biosynthesis / Q000235:genetics*; D011355:Prodrugs / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D001388:Aziridines; D011355:Prodrugs; C100099:tretazicar; D009601:Nitroreductases; D002945:Cisplatin