Identification and characterization of a novel class 3 aldehyde dehydrogenase overexpressed in a human breast adenocarcinoma cell line exhibiting oxazaphosphorine-specific acquired resistance.
Associated with the oxazaphosphorine-specific acquired resistance exhibited by a human breast adenocarcinoma subline growing in monolayer culture, viz. MCF-7/OAP, was the overexpression (> 100-fold as compared with the very small amount expressed in the oxazaphosphorine-sensitive parent line) of a class 3 aldehyde dehydrogenase, viz. ALDH-3, judged to be so because it is a polymorphic enzyme (pI values ca. 6.0) present in the cytosol that is heat labile, is insensitive to inhibition by disulfiram (25 microM), much prefers benzaldehyde to acetaldehyde as a substrate and, at concentrations of 4 mM, prefers NADP to NAD as a cofactor. No other aldehyde dehydrogenases were found in these cells. As compared with those of the prototypical class 3 human ALDH-3, viz. constitutive human stomach mucosa ALDH-3, the physical and catalytic properties of the MCF-7/OAP enzyme differed somewhat with regard to pI values, native M(r), subunit M(r), recognition of the subunit by anti-stomach ALDH-3 IgY, pH stability, cofactor influence on catalytic activity, and the ability to catalyze, albeit poorly, the oxidation of an oxazaphosphorine, viz. aldophosphamide. Hence, the MCF-7/OAP ALDH-3 was judged to be a novel class 3 aldehyde dehydrogenase. Small amounts of a seemingly identical enzyme are also present in normal pre- and post-menopausal breast tissue. None could be detected in human liver, kidney or placenta, suggesting that it may be a tissue-specific enzyme.
Sreerama
L
L
Department of Pharmacology, University of Minnesota Medical School, Minneapolis 55455.
Sladek
N E
NE
D000230:Adenocarcinoma / Q000188:drug therapy / Q000201:enzymology*; D000444:Aldehyde Dehydrogenase / Q000737:chemistry / Q000302:isolation & purification*; D001547:Benzaldehydes / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy / Q000201:enzymology*; D002460:Cell Line / Q000187:drug effects; D003520:Cyclophosphamide / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use; D004351:Drug Resistance; D005753:Gastric Mucosa / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000737:chemistry / Q000302:isolation & purification*; D009243:NAD; D009249:NADP; D013347:Subcellular Fractions / Q000201:enzymology; D013696:Temperature
D001547:Benzaldehydes; D007527:Isoenzymes; D009243:NAD; D009249:NADP; C048341:mafosfamide; D003520:Cyclophosphamide; D000444:Aldehyde Dehydrogenase; C032175:benzaldehyde; C011272:perfosfamide