| 1. |
- Uggla, Bertil, 1962-, et al.
(författare)
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Expression of topoisomerase IIalpha in the G0/G1 cell cycle phase of fresh leukemic cells
- 2001
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Ingår i: Leukemia Research. - Oxford, United Kingdom : Elsevier. - 0145-2126 .- 1873-5835. ; 25:11, s. 961-966
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Tidskriftsartikel (refereegranskat)abstract
- Topoisomerase IIalpha (topoII alpha) is the target enzyme for several antineoplastic drugs. Correlation between low expression of topo IIalpha and drug resistance has been shown in vitro, but there is limited evidence of a correlation to initial response to treatment or to overall prognosis. Normal cells express topo IIalpha in S/G2/M phase of the cell cycle but not in G0/G1 phase. However, some data suggest that topo IIalpha could be expressed in G0/G1 phase in malignant cells. We have investigated the expression of topo IIalpha in leukemic cells from 25 patients with acute leukemia by flow cytometry, separating cells of different cell cycle phases. We demonstrated that 9/25 samples showed >50% positive cells in G0/G1, and another five samples showed >20%. This finding could possibly provide an explanation to previous difficulties in correlating topo IIalpha expression with clinical outcome. Six of eight patients, where >20% of the cells in G0/G1 were positive for topo IIalpha, entered CR, compared to one of five patients with <20% topo IIalpha positive cells in G0/G1. We suggest that topo IIalpha expression in G0/G1 in leukemic cells may be of predictive value for clinical response to cytostatic drugs.
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| 2. |
- Villman, Kenneth, et al.
(författare)
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Topoisomerase II-α expression in different cell cycle phases in fresh human breast carcinomas
- 2002
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Ingår i: Modern Pathology. - Baltimore : Lippincott Williams & Wilkins. - 0893-3952 .- 1530-0285. ; 15:5, s. 486-491
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Tidskriftsartikel (refereegranskat)abstract
- Topoisomerase II-alfa (topo IIalfa) is the key target enzyme for the topoisomerase inhibitor class of anti-cancer drugs. In normal cells, topo IIalfa is expressed predominantly in the S/G2/M phase of the cell cycle. In malignant cells, in vitro studies have indicated that the expression of topo IIalfa is both higher and less dependent on proliferation state in the cell. We studied fresh specimens from 50 cases of primary breast cancer. The expression of topo IIalfa in different cell cycle phases was analyzed with two-parameter flow cytometry using the monoclonal antibody SWT3D1 and propidium iodide staining. The expression of topo IIalfa was significantly higher in the S/G2/M phase of the cell cycle than in the G0/G1 phase in both DNA diploid and DNA nondiploid tumors. In 18 of 21 diploid tumors, and in 25 of 29 nondiploid tumors, >50% of the topo IIalfa–positive cells were in the G0/G1 phase. This significant expression of topo IIalfa in the G0/G1 phase of the cell cycle may have clinically important implications for treatment efficacy of topoisomerase II inhibitors.
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