Improved efficacy of acylfulvene in colon cancer cells when combined with a nuclear excision repair inhibitor

Chem Res Toxicol. 2013 Nov 18;26(11):1674-82. doi: 10.1021/tx400255f. Epub 2013 Nov 5.

Abstract

The efficacy of DNA-damaging anticancer drugs is highly influenced by cellular DNA repair capacity, and by inhibiting the relevant DNA repair pathway, efficacy of alkylating agents may be increased. Therefore, combining DNA repair inhibitors with anticancer agents that selectively target tumor tissue should improve cancer treatment. The objective of this study was to test the hypothesis that cotreatment of cancer cells with acylfulvene (AF, alkylating agent) and UCN-01 (DNA repair inhibitor) would improve drug efficacy and promote the persistence of DNA adducts. Previous data regarding the relative susceptibility of repair proficient versus deficient cells toward an AF analogue suggests that corresponding adducts are repaired by nuclear excision repair (NER), a cellular process that has been shown to be prevented with UCN-01. In this study, cells were cotreated with nontoxic levels of UCN-01 together with increasing doses of AF. The efficacy of AF was assessed by measuring cytotoxicity and DNA adducts. In addition, cells were cotreated with nontoxic levels of methoxyamine, a known base excision repair (BER) inhibitor, to determine if inhibiting BER also promotes cytotoxicity of AF. DNA-adducts were measured in a sensitive and precise manner by using stable isotope-labeled mass spectrometry analysis. The data obtained in this study demonstrate for the first time that pharmacological inhibition of the NER pathway of DNA repair leads to the persistence of AF-specific adducts and promotes AF cytotoxicity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents, Alkylating / chemistry
  • Antineoplastic Agents, Alkylating / toxicity*
  • Cell Survival / drug effects
  • Chromatography, High Pressure Liquid
  • Colonic Neoplasms / metabolism
  • Colonic Neoplasms / pathology
  • DNA Adducts / analysis
  • DNA Adducts / metabolism
  • DNA Repair / drug effects*
  • DNA Repair Enzymes / antagonists & inhibitors
  • DNA Repair Enzymes / metabolism
  • Drug Synergism
  • HT29 Cells
  • Humans
  • Sesquiterpenes / chemistry
  • Sesquiterpenes / toxicity*
  • Spectrometry, Mass, Electrospray Ionization
  • Spiro Compounds / chemistry
  • Spiro Compounds / toxicity*
  • Staurosporine / analogs & derivatives*
  • Staurosporine / chemistry
  • Staurosporine / toxicity

Substances

  • Antineoplastic Agents, Alkylating
  • DNA Adducts
  • Sesquiterpenes
  • Spiro Compounds
  • acylfulvene
  • 7-hydroxystaurosporine
  • DNA Repair Enzymes
  • Staurosporine