title: Expression of the multidrug transporter P-glycoprotein is inversely related to that of apoptosis-associated endogenous TRAIL.
abstract: Multidrug resistance (MDR) has been associated with expression of ABC transporter genes including P-glycoprotein (Pgp, MDR1, ABCB1). However, deregulation of apoptotic pathways also renders cells resistant to chemotherapy. To discover apoptosis-related genes affected by Pgp expression, we used the HeLa MDR-off system. We found that using doxycycline to control Pgp expression has a significant advantage over tetracycline, in that doxycycline caused less endogenous gene expression modification/perturbation, and was more potent than tetracycline in suppressing Pgp expression. Cells overexpressing Pgp have lower TNFSF10 (TRAIL) expression than their parental cells. Controlled downregulation of Pgp increased endogenous TRAIL protein expression. Also, ectopic overexpression of TRAIL in Pgp-positive cells was associated with a reduction in Pgp levels. However, cells expressing a functionally defective mutant Pgp showed an increase in TRAIL expression, suggesting that Pgp function is required for TRAIL suppression. Cells in which Pgp is knocked down by upregulation of TRAIL expression are less susceptible to TRAIL ligand (sTRAIL)-induced apoptosis. Our findings reveal an inverse correlation between functional Pgp and endogenous TRAIL expression. Pgp function plays an important role in the TRAIL-mediated apoptosis pathway by regulating endogenous TRAIL expression and the TRAIL-mediated apoptosis pathway in MDR cancer cells.
authors.affiliation: Laboratory of Cell Biology, National Cancer Institute, Center for Cancer Research, National Institutes of Health, USA; Laboratório de Hemato-Oncologia Celular e Molecular, Programa de Pesquisa em Hemato-Oncologia Molecular, Instituto Nacional de Câncer (INCA), Brazil.
authors.forename: Paloma S
authors.initials: PS
authors.lastname: Souza
authors.affiliation: Laboratory of Cell Biology, National Cancer Institute, Center for Cancer Research, National Institutes of Health, USA.
authors.forename: James P
authors.initials: JP
authors.lastname: Madigan
authors.affiliation: Laboratory of Cell Biology, National Cancer Institute, Center for Cancer Research, National Institutes of Health, USA.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Gillet
authors.affiliation: Laboratory of Cell Biology, National Cancer Institute, Center for Cancer Research, National Institutes of Health, USA.
authors.forename: Khyati
authors.initials: K
authors.lastname: Kapoor
authors.affiliation: Laboratory of Cell Biology, National Cancer Institute, Center for Cancer Research, National Institutes of Health, USA.
authors.forename: Suresh V
authors.initials: SV
authors.lastname: Ambudkar
authors.affiliation: Laboratório de Hemato-Oncologia Celular e Molecular, Programa de Pesquisa em Hemato-Oncologia Molecular, Instituto Nacional de Câncer (INCA), Brazil.
authors.forename: Raquel C
authors.initials: RC
authors.lastname: Maia
authors.affiliation: Laboratory of Cell Biology, National Cancer Institute, Center for Cancer Research, National Institutes of Health, USA. Electronic address: mgottesman@nih.gov.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Gottesman
authors.affiliation: Laboratory of Cell Biology, National Cancer Institute, Center for Cancer Research, National Institutes of Health, USA.
authors.forename: King Leung
authors.initials: KL
authors.lastname: Fung
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000235:genetics*; D017209:Apoptosis / Q000235:genetics*; D045744:Cell Line, Tumor; D015536:Down-Regulation; D004318:Doxycycline / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D034622:RNA Interference; D034741:RNA, Small Interfering; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000096:biosynthesis / Q000235:genetics*; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D034741:RNA, Small Interfering; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D013752:Tetracycline; D004318:Doxycycline
keywords: ABCB1; MDR1; TET-Off; TNFSF10; TRAIL; apoptosis; multidrug resistance