title: Sanguinarine overcomes P-glycoprotein-mediated multidrug-resistance via induction of apoptosis and oncosis in CEM-VLB 1000 cells.
abstract: Permeability-glycoprotein (Pgp) positive cells are known to be encoded by the multidrug-resistance gene (MDR1), and characterized by a reduced ability to accumulate drugs. The vinblastin-resistant, Pgp positive CEM-VLB 1000 and its wild type (Pgp-negative and vinblastin-sensitive) counterpart CEM-T4 human leukemia cells, when treated with the alkaloid sanguinarine, were both found to undergo apoptosis at concentrations of 1.5 microg/ml and oncosis/blister cell death (BCD) at concentrations of 12.5 microg/ml. The aim of this study was to assess the ability of sanguinarine to overcome Pgp-mediated multidrug-resistance (MDR), and also to characterize the cell death processes of apoptosis and oncosis (or bimodal cell death) induced by sanguinarine in MDR cells. The cell death processes of apoptosis and oncosis in CEM-VLB 1000 and CEM-T4 cell lines were found to be qualitatively similar when assessed by light microscopy, terminal deoxynucleotidyl transferase (TdT) end-labeling, annexin-V-binding, trypan blue exclusion and western blot analysis. Western blotting revealed an increase in the Bax/Bcl-2 ratio and activation of caspase-3 in apoptosis but not oncosis in both cell lines. The Pgp-positive CEM-VLB 1000 cells and their wild type CEM-T4 cells were both equally sensitive to sanguinarine. Thus, sanguinarine may overcome the phenomenon of Pgp-mediated MDR by inducing apoptosis through increasing the Bax/Bcl-2 ratio and activating caspase-3, and oncosis, which involved neither.
authors.affiliation: Faculty of Medicine, Memorial University of Newfoundland, 300 Prince Phillip Drive, St. John's, Newfoundland, Canada A1B 3V6. priyaw@bcm.tmc.edu
authors.forename: Priya
authors.initials: P
authors.lastname: Weerasinghe
authors.forename: Sarathi
authors.initials: S
authors.lastname: Hallock
authors.forename: Shou-Ching
authors.initials: SC
authors.lastname: Tang
authors.forename: Benjamin
authors.initials: B
authors.lastname: Trump
authors.forename: Andrejs
authors.initials: A
authors.lastname: Liepins
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors*; D000470:Alkaloids / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053119:Benzophenanthridines; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D020287:In Situ Nick-End Labeling; D007546:Isoquinolines; D007938:Leukemia / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D009336:Necrosis / Q000188:drug therapy; D010617:Phenanthridines / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000470:Alkaloids; D053119:Benzophenanthridines; D007546:Isoquinolines; D010617:Phenanthridines; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; C005705:sanguinarine; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases