title: [Study on the relationship between DNA topoisomerase II activity and multidrug resistance in leukemic cells].
abstract: OBJECTIVE
  To explore the relationship between DNA topoisomerase II (Topo II) activity and multidrug resistance in acute leukemia(AL).
  
  
  METHODS
  Topo II activities were measured in peripheral blood or bone marrow leukemia cells from 17 pretreated patients and 20 after combination chemotherapy by fluorometric assay. In the same time, multidrug resistant p-glycoprotein expression was detected by immunohistochemistry using JSB-1 monoclonal antibody and mdr-1 gene expression was assayed by RT-PCR in 18 post-chemotherapy patients.
  
  
  RESULTS
  Topo II activities were significantly higher in pretreated AL patients (0.6415 +/- 0.0561) than in healthy blood donors (0.2304 +/- 0.0591)(P < 0.005) and significantly lower in post-chemotherapy patients (0.3563 +/- 0.1011) than in pretreated ones (P < 0.005). Among 15 poorly responsed patients, 12 were p170 positive and mdr-1 overexpression, 3 case were p170 negative. Topo II activity was also decreased in these poor responsers.
  
  
  CONCLUSIONS
  Decreased Topo II activity may be another factor in multidrug resistance.
authors.affiliation: Department of Hematology, Xiangya Hospital, Hunan Medical University, Changsha 410008.
authors.forename: W
authors.initials: W
authors.lastname: Zheng
authors.forename: Z
authors.initials: Z
authors.lastname: Xie
authors.forename: G
authors.initials: G
authors.lastname: Tang
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis*; D000293:Adolescent; D000328:Adult; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005260:Female; D019450:Genes, MDR; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000201:enzymology* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000201:enzymology* / Q000235:genetics; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004250:DNA Topoisomerases, Type II