Differences among allelic variants of human glutathione transferase A2-2 in the activation of azathioprine
2010 (English)In: Chemico-Biological Interactions, ISSN 0009-2797, E-ISSN 1872-7786, Vol. 186, no 2, 110-117 p.Article in journal (Refereed) Published
Azathioprine has been clinically used for decades in connection with organ transplantation, autoimmune disease, and treatment of cancer. Toxic side-reactions are common and have been linked to the liberation of excessively high concentrations of 6-mercaptopurine and corresponding toxic metabolites. An allelic variant of thiopurine methyltransferase with low activity is associated with elevated concentrations of 6-mercaptopurine. However, other genetic markers remain to be identified in order to fully account for adverse reactions and efficacy failure. In the present study, we studied the five known allelic variants of human glutathione transferase A2-2 (GST A2-2) (EC188.8.131.52), abundantly expressed in liver and efficiently catalyzing the bioactivation of azathioprine to release 6-mercaptopurine. All five variants exhibited high activity with azathioprine, but allelic variant E of GST A2-2 displayed a 3-4-fold elevated catalytic efficiency compared to the other variants. High GST activity can lead to overproduction of 6-mercaptopurine, and the nature of the multiple forms of GSTs in a patient will obviously affect the metabolism of azathioprine. In addition to GST A2-2, the polymorphic GST M1-1 is also highly active with azathioprine. Considering our findings, it appears that the genotypic and phenotypic variations in the GST complement may influence the presentation of adverse reactions in patients treated with azathioprine. Clinical trials will be required to clarify the impact of the GST expression in comparison with the established biomarker thiopurine methyltransferase as predictors of adverse reactions.
Place, publisher, year, edition, pages
2010. Vol. 186, no 2, 110-117 p.
Azathioprine, Glutathione transferase, Bioactivation, Thiopurine methyltransferase, Allelic variants, Polymorphism
Biochemistry and Molecular Biology Biocatalysis and Enzyme Technology
IdentifiersURN: urn:nbn:se:uu:diva-135839DOI: 10.1016/j.cbi.2010.04.028ISI: 000279644900002OAI: oai:DiVA.org:uu-135839DiVA: diva2:375720