QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: dmd.107.018895v1 36/5/904    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bains, O. S. Articles by Riggs, K. W. Search for Related Content PubMed PubMed Citation Articles by Bains, O. S. Articles by Riggs, K. W.

Two Allelic Variants of Aldo-Keto Reductase 1A1 Exhibit Reduced in Vitro Metabolism of Daunorubicin

Division of Pharmaceutics and Biopharmaceutics, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada (O.S.B., R.H.T., K.W.R.); Life Sciences Institute, Department of Zoology, Faculty of Science, University of British Columbia, Vancouver, British Columbia, Canada (T.A.P., T.A.G.); Division of Biomolecular and Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada (R.E.R.)

Aldo-keto reductases (AKRs) are a class of NADPH-dependent oxidoreductases that have been linked to metabolism of the anthracyclines doxorubicin (DOX) and daunorubicin (DAUN). Although widely used, cardiotoxicity continues to be a serious side effect that may be linked to metabolites or reactive intermediates generated in their metabolism. In this study we examine the little known effects of nonsynonymous single nucleotide polymorphisms of human AKR1A1 on the metabolism of these drugs to their alcohol metabolites. Expressed and purified from bacteria using affinity chromatography, the AKR1A1 protein with a single histidine (6x-His) tag exhibited the greatest activity using two test substrates: p-nitrobenzaldehyde (5.09 ± 0.16 µmol/min/mg of purified protein) and DL-glyceraldehyde (1.24 ± 0.17 µmol/min/mg). These activities are in agreement with published literature values of nontagged human AKR1A1. The 6x-His-tagged AKR1A1 wild type and allelic variants, E55D and N52S, were subsequently examined for metabolic activity using DAUN and DOX. The tagged variants showed significantly reduced activities (1.10 ± 0.42 and 0.72 ± 0.47 nmol of daunorubicinol (DAUNol) formed/min/mg of purified protein for E55D and N52S, respectively) compared with the wild type (2.34 ± 0.71 nmol/min/mg). The wild type and E55D variant metabolized DOX to doxorubicinol (DOXol); however, the levels fell below the limit of quantitation (25 nM). The N52S variant yielded no detectable DOXol. A kinetic analysis of the DAUN reductase activities revealed that both amino acid substitutions lead to reduced substrate affinity, measured as significant increases in the measured K_m for the reduction reaction by AKR1A1. Hence, it is possible that these allelic variants can act as genetic biomarkers for the clinical development of DAUN-induced cardiotoxicity.

This article has been cited by other articles:

				O. S. Bains, M. J. Karkling, T. A. Grigliatti, R. E. Reid, and K. W. Riggs Two Nonsynonymous Single Nucleotide Polymorphisms of Human Carbonyl Reductase 1 Demonstrate Reduced in Vitro Metabolism of Daunorubicin and Doxorubicin Drug Metab. Dispos., May 1, 2009; 37(5): 1107 - 1114. [Abstract] [Full Text] [PDF]

				E. Salvatorelli, P. Menna, M. Lusini, E. Covino, and G. Minotti Doxorubicinolone Formation and Efflux: A Salvage Pathway against Epirubicin Accumulation in Human Heart J. Pharmacol. Exp. Ther., April 1, 2009; 329(1): 175 - 184. [Abstract] [Full Text] [PDF]

				N. Kassner, K. Huse, H.-J. Martin, U. Godtel-Armbrust, A. Metzger, I. Meineke, J. Brockmoller, K. Klein, U. M. Zanger, E. Maser, et al. Carbonyl Reductase 1 Is a Predominant Doxorubicin Reductase in the Human Liver Drug Metab. Dispos., October 1, 2008; 36(10): 2113 - 2120. [Abstract] [Full Text] [PDF]