De novo expression of transfected human class 1 aldehyde dehydrogenase (ALDH) causes resistance to oxazaphosphorine anti-cancer alkylating agents in hamster V79 cell lines. Elevated class 1 ALDH activity is closely correlated with reduction in DNA interstrand cross-linking and lethality

J Biol Chem. 1996 May 17;271(20):11884-90. doi: 10.1074/jbc.271.20.11884.


Human class 1 aldehyde dehydrogenase (hALDH-1) can oxidize aldophosphamide, a key aldehyde intermediate in the activation pathway of cyclophosphamide and other oxazaphosphorine (OAP) anti-cancer alkylating agents. Overexpression of class 1 ALDH (ALDH-1) has been observed in cells selected for survival in the presence of OAPs. We used transfection to induce de novo expression of human ALDH-1 in V79/SD1 Chinese hamster cells to clearly quantitate the role of hALDH-1 expression in OAP resistance. Messenger RNA levels correlated well with hALDH-1 protein levels and enzyme activities (1.5-13.6 milliunits/mg with propionaldehyde/NAD+ substrate, compared to < 1 milliunit/mg in controls) in individual clonal transfectant lines, and slot blot analysis confirmed the presence of the transfected cDNA. Expressed ALDH activity was closely correlated (r = 0.99) with resistance to mafosfamide, up to 21-fold relative to controls. Transfectants were cross-resistant to other OAPs but not to phosphoramide mustard, ifosfamide mustard, melphalan, or acrolein. Resistance was completely reversed by pretreatment with 25 microM diethylaminobenzaldehyde, a potent ALDH inhibitor. Alkaline elution studies showed that expression of ALDH-1 reduced the number of DNA cross-links commensurate with mafosfamide resistance, and this reduction in cross-links was fully reversed by the inhibitor. Thus, overexpression of human class 1 ALDH alone is sufficient to confer OAP-specific drug resistance.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aldehyde Dehydrogenase / antagonists & inhibitors
  • Aldehyde Dehydrogenase / genetics
  • Aldehyde Dehydrogenase / physiology*
  • Animals
  • Antineoplastic Agents, Alkylating / pharmacology*
  • Base Sequence
  • Cell Line
  • Cricetinae
  • Cricetulus
  • Cyclophosphamide / analogs & derivatives
  • Cyclophosphamide / pharmacology
  • DNA / metabolism*
  • Drug Resistance
  • Enzyme Inhibitors / pharmacology
  • Humans
  • Isoenzymes / physiology*
  • Molecular Sequence Data
  • Phosphoramide Mustards / pharmacology
  • Transfection


  • Antineoplastic Agents, Alkylating
  • Enzyme Inhibitors
  • Isoenzymes
  • Phosphoramide Mustards
  • phosphoramide mustard
  • mafosfamide
  • Cyclophosphamide
  • DNA
  • Aldehyde Dehydrogenase