title: Signal pathways in ouabain-induced proliferation of leukemia cells.
abstract: BACKGROUND
  Cardiotonic steroids (CTSs) can bind to Na(+)/K(+)-ATPase and activate protein kinase cascades, resulting in changes in cell proliferation, differentiation or apoptosis in a cell-specific manner. We explored the participation of ouabain-activated signaling pathways in growth regulation of leukemia cells.
  
  
  METHODS
  Lymphocytic leukemia Jhhan cells and megakaryocytic leukemia M07e cells were incubated at different concentrations of ouabain (0, 1 and 10 nmol) for 24 hours. Cell proliferation was measured by methyl thiazolyl tetrazolium (MTT) assay. To probe the role of ouabain-induced signaling in control of cell growth, we employed Src kinase inhibitor PP2 and the MEK inhibitor PD98059, respectively. The expression of Na(+)/K(+)-ATPase alpha1 subunit of leukemia cells was evaluated by RT-PCR and Western blotting.
  
  
  RESULTS
  One nmol and 10 nmol ouabain promoted proliferation of both Jhhan and M07e cells. Ouabain also up-regulated the expression of Na(+)/K(+)-ATPase alpha1 subunit. Addition of either PP2 or PD98059 blocked the effects of ouabain on cell proliferation.
  
  
  CONCLUSIONS
  Ouabain activates Src and ERK1/2 pathways and regulates the proliferation of leukemia cells.
authors.affiliation: Pediatric Department, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
authors.forename: Jia-Wei
authors.initials: JW
authors.lastname: Xu
authors.forename: Run-Ming
authors.initials: RM
authors.lastname: Jin
authors.forename: En-Qin
authors.initials: EQ
authors.lastname: Li
authors.forename: Yan-Rong
authors.initials: YR
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Bai
mesh_terms: D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007945:Leukemia, Lymphoid / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D007947:Leukemia, Megakaryoblastic, Acute / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D010042:Ouabain / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects*
chemical_list: D004791:Enzyme Inhibitors; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase