title: Sensitization of colorectal and pancreatic cancer cell lines to the prodrug 5-(aziridin-1-yl)-2,4-dinitrobenzamide (CB1954) by retroviral transduction and expression of the E. coli nitroreductase gene.
abstract: Expression of genes encoding prodrug-activating enzymes can increase the susceptibility of tumor cells to prodrugs, and may ultimately achieve a better therapeutic index than conventional chemotherapy. CB1954 is a weak, monofunctional alkylating agent which can be activated by Escherichia coli nitroreductase to a potent dysfunctional alkylating agent which crosslinks DNA. We have inserted the nitroreductase gene into an LNCX-based retroviral vector, to allow efficient gene transfer and expression in colorectal (LS174T) and pancreatic (SUIT2, BxPC3, and AsPC1) cancer cell lines. A clone of LS174T cells expressing nitroreductase showed > 50-fold increased sensitivity to CB1954, and nitroreductase-expressing clones of pancreatic tumor lines were up to approximately 500-fold (SUIT2) more sensitive than parental cells. Concentrations of CB1954 minimally toxic to nontransduced cells achieved 100% cell death in a 50:50 mix of parental cells with SUIT2 cells expressing nitroreductase; and marked "bystander" cell killing was seen with just 10% of cells expressing nitroreductase. Significant bystander cell killing was dependent on a high cell density. In conjunction with regional delivery of vectors and tumor selectivity of cell entry and/or gene expression, nitroreductase and CB1954 may be an attractive combination for prodrug-activating enzyme gene therapy of colorectal and pancreatic cancer.
authors.affiliation: Department of Surgery, University of Birmingham, UK.
authors.forename: N K
authors.initials: NK
authors.lastname: Green
authors.forename: D J
authors.initials: DJ
authors.lastname: Youngs
authors.forename: J P
authors.initials: JP
authors.lastname: Neoptolemos
authors.forename: F
authors.initials: F
authors.lastname: Friedlos
authors.forename: R J
authors.initials: RJ
authors.lastname: Knox
authors.forename: C J
authors.initials: CJ
authors.lastname: Springer
authors.forename: G M
authors.initials: GM
authors.lastname: Anlezark
authors.forename: N P
authors.initials: NP
authors.lastname: Michael
authors.forename: R G
authors.initials: RG
authors.lastname: Melton
authors.forename: M J
authors.initials: MJ
authors.lastname: Ford
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: D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001388:Aziridines / Q000494:pharmacology / Q000627:therapeutic use*; D015179:Colorectal Neoplasms / Q000628:therapy*; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000235:genetics; D015316:Genetic Therapy; D005822:Genetic Vectors; D006801:Humans; D009601:Nitroreductases / Q000235:genetics*; D010190:Pancreatic Neoplasms / Q000628:therapy*; D011355:Prodrugs / Q000494:pharmacology / Q000627:therapeutic use*; D012190:Retroviridae; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D001388:Aziridines; D011355:Prodrugs; C100099:tretazicar; D009601:Nitroreductases