title: Arsenic trioxide inhibits p-glycoprotein expression in multidrug-resistant human leukemia cells that overexpress the MDR1 gene.
abstract: OBJECTIVE
  To investigate the effects of arsenic trioxide (As(2)O(3)) on the apoptosis and p-glycoprotein (P-gp) expression of multidrug-resistant human leukemia cells.
  
  
  METHODS
  Human multidrug-resistant leukemia cell line K562/ADM overexpressing the MDR1 gene, was used as the target cells. The cell proliferating activity was assessed using the MTT colorimetric assay. Cytomorphology was investigated under light, confocal and electron microscopes. DNA fragmentation was examined using agarose gel electrophoresis, while p-gp expression, cell cycle status and sub-G1 cells were determined using flow cytometry.
  
  
  RESULTS
  Zero point five to 20 micromol/L As(2)O(3) inhibited the proliferation of K562/ADM cells, and K562/ADM cells were more sensitive to As(2)O(3) than the parental K562 cells. As(2)O(3)-induced apoptosis of K562/ADM cells was determined by the observance of typical morphological changes and the appearance of DNA ladder and sub-G1 cell populations. As(2)O(3) significantly inhibited the P-gp expression of K562/ADM cells, and synergistically enhanced the sensitivity of the drug-resistant cells to adriamycin.
  
  
  CONCLUSIONS
  As(2)O(3) induces growth-inhibition and apoptosis, down-regulates P-gp expression and exerts a synergistic effect in combination with adriamycin in multidrug-resistant leukemia cells.
authors.affiliation: Laboratory Center for Medical Science, Lanzhou Medical College, Lanzhou 730000, China. weihl@public.lz.gs.cn
authors.forename: Hulai
authors.initials: H
authors.lastname: Wei
authors.forename: Haixiang
authors.initials: H
authors.lastname: Su
authors.forename: Decheng
authors.initials: D
authors.lastname: Bai
authors.forename: Huaishun
authors.initials: H
authors.lastname: Zhao
authors.forename: Jianguo
authors.initials: J
authors.lastname: Ge
authors.forename: Bei
authors.initials: B
authors.lastname: Wang
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Yao
authors.forename: Lanfang
authors.initials: L
authors.lastname: Ma
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis*; D017209:Apoptosis / Q000187:drug effects; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology*; D018432:Drug Resistance, Multiple; D015870:Gene Expression; D019450:Genes, MDR; D006801:Humans; D007938:Leukemia / Q000235:genetics / Q000378:metabolism*; D010087:Oxides / Q000494:pharmacology*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D001152:Arsenicals; D010087:Oxides; D000077237:Arsenic Trioxide