title: Progressive resistance of BTK-143 osteosarcoma cells to Apo2L/TRAIL-induced apoptosis is mediated by acquisition of DcR2/TRAIL-R4 expression: resensitisation with chemotherapy.
abstract: Apo2 ligand (Apo2L, also known as TRAIL) is a member of the tumour necrosis factor (TNF) family of cytokines that selectively induces the death of cancer cells, but not of normal cells. We observed that recombinant Apo2L/TRAIL was proapoptotic in early-passage BTK-143 osteogenic sarcoma cells, inducing 80% cell death during a 24 h treatment period. Apo2L/TRAIL-induced apoptosis was blocked by caspase inhibition. With increasing passage in culture, BTK-143 cells became progressively resistant to the apoptotic effects of Apo2L/TRAIL. RNA and flow cytometric analysis demonstrated that resistance to Apo2L/TRAIL was paralleled by progressive acquisition of the decoy receptor, DcR2. Blocking of DcR2 function with a specific anti-DcR2 antibody restored sensitivity to Apo2L/TRAIL in a dose-dependent manner. Importantly, treatment of resistant cells with the chemotherapeutic agents doxorubicin, cisplatin and etoposide reversed the resistance to Apo2L/TRAIL, which was associated with drug-induced upregulation of mRNA encoding the death receptors DR4 and DR5. BTK-143 cells thus represent a useful model system to investigate both the mechanisms of acquisition of resistance of tumour cells to Apo2L/TRAIL and the use of conventional drugs and novel agents to overcome resistance to Apo2L/TRAIL.
authors.affiliation: Department of Orthopaedics and Trauma, University of Adelaide, Level 4, Bice Building, Royal Adelaide Hospital, North Terrace, Adelaide 5000, South Australia, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Bouralexis
authors.forename: D M
authors.initials: DM
authors.lastname: Findlay
authors.forename: G J
authors.initials: GJ
authors.lastname: Atkins
authors.forename: A
authors.initials: A
authors.lastname: Labrinidis
authors.forename: S
authors.initials: S
authors.lastname: Hay
authors.forename: A
authors.initials: A
authors.lastname: Evdokiou
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D019008:Drug Resistance, Neoplasm; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008024:Ligands; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D012516:Osteosarcoma / Q000473:pathology*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D019014:fas Receptor
chemical_list: D051017:Apoptosis Regulatory Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor