Effects of topoisomerase I inhibition on the expression of topoisomerase IIα measured with fluorescence image cytometry

Autor: David W. Hedley, Trudey Nicklee, Michael Crump
Rok vydání: 1996
Předmět:
Zdroj: Cytometry. 25:205-210
ISSN: 1097-0320
0196-4763
DOI: 10.1002/(sici)1097-0320(19961101)25:3<205::aid-cyto1>3.0.co;2-e
Popis: A fluorescence image cytometry technique was developed to measure the effects of topotecan, a topoisomerase I inhibitor, on the nuclear expression of topoisomerase IIα in a series of patients with refractory or relapsed acute myeloid leukemia (AML). We used a commercially available affinity-purified rabbit polyclonal antibody and a fluorescein-conjugated secondary antibody. By using DAPI as a DNA counterstain and dual wavelength excitation, it was possible to measure enzyme expression in the cell nucleus, and to examine its cell cycle phase distribution. In human acute leukemia cell lines, topoisomerase IIα expression was greatest in late S and G2 phases, but in leukemia patient samples the enzyme expression appeared to be much less cell cycle dependent. There was considerable interpatient variation in the effects of topotecan on topoisomerase IIα expression in the leukemia patients, with a threefold increase in the median value after 48 h followed by a decline to pretreatment levels after 5 days of treatment with the topoisomerase I inhibitor. Although these findings should be treated with caution because of the small number of cases studied, they support the prediction that topoisomerase I inhibitors might be capable of increasing sensitivity to topoisomerase II active drugs such as anthracyclines and epipodophyllotoxins by upregulating topoisomerase II expression. They also illustrate the potential value of fluorescence image cytometry for making sequential measurements of the effects of drug resistance modulating agents in cancer patients. © 1996 Wiley-Liss, Inc.
Databáze: OpenAIRE
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