title: Indomethacin-induced activation of the death receptor-mediated apoptosis pathway circumvents acquired doxorubicin resistance in SCLC cells.
abstract: Small-cell lung cancers (SCLCs) initially respond to chemotherapy but are often resistant at recurrence. A potentially new method to overcome resistance is to combine classical chemotherapeutic drugs with apoptosis induction via tumour necrosis factor (TNF) death receptor family members such as Fas. The doxorubicin-resistant human SCLC cell line GLC4-Adr and its parental doxorubicin-sensitive line GLC4 were used to analyse the potential of the Fas-mediated apoptotic pathway and the mitochondrial apoptotic pathway to modulate doxorubicin resistance in SCLC. Western blotting showed that all proteins necessary for death-inducing signalling complex formation and several inhibitors of apoptosis were expressed in both lines. The proapototic proteins Bid and caspase-8, however, were higher expressed in GLC4-Adr. In addition, GLC4-Adr expressed more Fas (3.1x) at the cell membrane. Both lines were resistant to anti-Fas antibody, but plus the protein synthesis inhibitor cycloheximide anti-Fas antibody induced 40% apoptosis in GLC4-Adr. Indomethacin, which targets the mitochondrial apoptotic pathway, induced apoptosis in GLC4-Adr but not in GLC4 cells. Surprisingly, in GLC4-Adr indomethacin induced caspase-8 and caspase-9 activation as well as Bid cleavage, while both caspase-8 and caspase-9 specific inhibitors blocked indomethacin-induced apoptosis. In GLC4-Adr, doxorubicin plus indomethacin resulted in elevated caspase activity and a 2.7-fold enhanced sensitivity to doxorubicin. In contrast, no effect of indomethacin on doxorubicin sensitivity was observed in GLC4. Our findings show that indomethacin increases the cytotoxic activity of doxorubicin in a doxorubicin-resistant SCLC cell line partly via the death receptor apoptosis pathway, independent of Fas.
authors.affiliation: Department of Medical Oncology, University Medical Center Groningen, PO Box 30.001, 9700 RB, Groningen, The Netherlands.
authors.forename: D J A
authors.initials: DJ
authors.lastname: de Groot
authors.forename: T
authors.initials: T
authors.lastname: Timmer
authors.forename: D C J
authors.initials: DC
authors.lastname: Spierings
authors.forename: T K P
authors.initials: TK
authors.lastname: Le
authors.forename: S
authors.initials: S
authors.lastname: de Jong
authors.forename: E G E
authors.initials: EG
authors.lastname: de Vries
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D051023:BH3 Interacting Domain Death Agonist Protein; D015153:Blotting, Western; D018288:Carcinoma, Small Cell / Q000188:drug therapy; D002352:Carrier Proteins / Q000187:drug effects / Q000378:metabolism; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D005434:Flow Cytometry; D006801:Humans; D007213:Indomethacin / Q000494:pharmacology*; D008175:Lung Neoplasms / Q000188:drug therapy; D018613:Microscopy, Confocal; D012333:RNA, Messenger / Q000032:analysis; D018124:Receptors, Tumor Necrosis Factor / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019014:fas Receptor
chemical_list: D000903:Antibiotics, Antineoplastic; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D002352:Carrier Proteins; D016861:Cyclooxygenase Inhibitors; C491901:FAS protein, human; D012333:RNA, Messenger; D018124:Receptors, Tumor Necrosis Factor; D019014:fas Receptor; D004317:Doxorubicin; D020169:Caspases; D007213:Indomethacin