title: P-glycoprotein is not involved in pathway of anti-Fas/Fas-induced apoptosis in KBv200 cells.
abstract: OBJECTIVE
  To verify whether P-glycoprotein (P-gp) could induce cell resistance to apoptosis by inhibiting caspase-8 and caspase-3.
  
  
  METHODS
  Human KB cells, either drug-sensitive or with multidrug resistance (MDR) phenotype caused by overexpression of P-gp (KBv200 cells), were treated with anti-Fas (CH-11 monoclonal antibody) to induce apoptosis. Cytotoxicity was detected by MTT assay. Symptoms of cell death were assessed by morphological observation after Hoechst33258 staining, activation of caspase-8 and caspase-3 was measured by Western blotting.
  
  
  RESULTS
  Compared with KB cells, the resistance of KBv200 cells to VCR (vincristine) was about 51-fold higher. Anti-Fas (CH-11) induced cytotoxicity and apoptosis in both sensitive KB cells and MDR phenotype KBv200 cells. The IC50 of CH-11 in KB cells was similar to that in KBv200 cells. CH-11 induced similar apoptotic rates in both KB cells and KBv200 cells, which could be classified as caspase-dependent apoptotic pathway. Verapamil (VRP) did not affect CH-11-mediated apoptosis in KBv200 cells.
  
  
  CONCLUSIONS
  Expression of P-glycoprotein does not induce resistance to caspase-8 and -3 activation or anti-Fas-induced cell apoptosis.
authors.affiliation: Department of Pathology, Cancer Center, Sun Yat-Sen University, Guangzhou 510060, Guangdong Province, China.
authors.forename: Qiu-Liang
authors.initials: QL
authors.lastname: Wu
authors.forename: Xing-Ping
authors.initials: XP
authors.lastname: Wu
authors.forename: Yong-Ju
authors.initials: YJ
authors.lastname: Liang
authors.forename: Li-Ming
authors.initials: LM
authors.lastname: Chen
authors.forename: Yan
authors.initials: Y
authors.lastname: Ding
authors.forename: Li-Wu
authors.initials: LW
authors.lastname: Fu
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D018432:Drug Resistance, Multiple; D006801:Humans; D007624:KB Cells; D014750:Vincristine / Q000633:toxicity; D019014:fas Receptor / Q000276:immunology / Q000502:physiology*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D019014:fas Receptor; D014750:Vincristine; C505407:CASP3 protein, human; C505530:CASP8 protein, human; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases