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.

Abstract

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.

• Authors: K D Bunting, A J Townsend
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 271 Issue 20 Pg. 11884-90 (May 17 1996) ISSN: 0021-9258 [Print] United States
• PMID: 8662658 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

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

Topics

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