Rapid Method to Measure Thioguanine Incorporation Into DNA
2011 (English)In: European Journal of Cancer, ISSN 0959-8049, E-ISSN 1879-0852, Vol. 47, no Supplement 1, S650-S650 p.Article in journal, Meeting abstract (Other academic) Published
Background: The thiopurine drugs, 6-mercaptopurine, azathioprine, and thioguanine, are used in the treatment of acute lymphoblastic leukaemia (ALL). During treatment the thioguanine nucleotides formed are incorporated into the DNA, causing apoptosis due to the cells inability to repair the resulting damage. This mechanism is believed to be important for the effects of thiopurine drugs. We have developed a novel method for the determination of thioguanine incorporation into DNA which is both faster and cheaper than earlier methods.
Monitoring the effects of thiopurine treatment by measuring thiopurine metabolites in erythrocytes has proven to be elusive due to the lack of good correlation between measured concentrations and thiopurine effects. If the incorporation is the main mechanism of thiopurine action, a reliable method capable of measuring the incorporation in an ordinary blood sample, such as the method we have developed, should provide a significantly better correlation with treatment effect.
Material and Methods: Briefly, DNA extracted from buffy coat is degraded using nuclease P1 and alkaline phosphatase to produce free nucleosides which are purified by filtration. Thioguanosine and thymidine are separated and detected using an LC-MS/MS system and the ratio between the bases provides a measurement of the extent of thioguanine incorporation in DNA. The method has been successfully applied to cell culture samples as well as samples from patients treated orally with thiopurines.
Results: In 8 inflammatory bowel disease patients treated with azathioprine the measured incorporation ranged from 2.2 to 8.4 thioguanine bases for every 10 000 thymidine bases (median 5.2). This is in agreement with earlier reports on incorporation in childhood leukemia patients.
Conclusions: With the presented method it is possible to determine the incorporation of thioguanine into DNA during thiopurine treatment in a cost effective manner, but further research is needed to determine if there is a place for this type of methods in the monitoring of thiopurine treatment.
An ongoing study aims to compare the incorporation to treatment effects as well as conventional measurements of erythrocyte metabolite levels. By this study we hope to determine if incorporation is a more reliable measurement to predict treatment effect and if the erythrocyte metabolite levels correlate with the incorporation.
Place, publisher, year, edition, pages
Elsevier, 2011. Vol. 47, no Supplement 1, S650-S650 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-71807DOI: 10.1016/S0959-8049(11)72504-7ISI: 000295752802299OAI: oai:DiVA.org:liu-71807DiVA: diva2:453982
2011 European Multidisciplinary Cancer Congress, Stockholm, Sweden, SEP 23-27, 2011