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

Cancer Gene Ther. Jul-Aug 1997;4(4):229-38.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Antineoplastic Agents / therapeutic use*
  • Aziridines / pharmacology
  • Aziridines / therapeutic use*
  • Colorectal Neoplasms / therapy*
  • Dose-Response Relationship, Drug
  • Escherichia coli / genetics
  • Genetic Therapy*
  • Genetic Vectors
  • Humans
  • Nitroreductases / genetics*
  • Pancreatic Neoplasms / therapy*
  • Prodrugs / pharmacology
  • Prodrugs / therapeutic use*
  • Retroviridae
  • Tumor Cells, Cultured

Substances

  • Antineoplastic Agents
  • Aziridines
  • Prodrugs
  • tretazicar
  • Nitroreductases