title: Downregulation of Bcl-2, FLIP or IAPs (XIAP and survivin) by siRNAs sensitizes resistant melanoma cells to Apo2L/TRAIL-induced apoptosis.
abstract: Melanoma cells are relatively resistant to Apo2L/TRAIL (TNF-related apoptosis-inducing ligand). We postulated that resistance might result from higher expression of inhibitors of apoptosis including Bcl-2, FLIP (FLICE-like inhibitory protein) or IAPs such as XIAP (X-linked inhibitor of apoptosis) or survivin. Compared to scrambled or mismatch controls, targeting individual inhibitors with siRNA (si-Bcl-2, si-XIAP, si-FLIP or si-Surv), followed by Apo2L/TRAIL resulted in marked increase in apoptosis in melanoma cells. Compared to Bcl-2 or FLIP, siRNAs against XIAP and survivin were most potent in sensitizing melanoma cells. A similar substantial increase in apoptosis was seen in renal carcinoma cells (SKRC-45, Caki-2), following the inhibition of either XIAP or survivin by siRNAs. Apo2L/TRAIL treatment in IAP-targeted cells resulted in cleavage of Bid, activation of caspase-9 and cleavage of PARP (poly ADP-ribose polymerase). Thus, Apo2L/TRAIL resistance can be overcome by interfering with expression of inhibitors of apoptosis regulating both extrinsic (death receptor) or intrinsic (mitochondrial) pathways of apoptosis in melanoma cells.
authors.affiliation: Center for Drug Discovery and Development, Taussig Cancer Center, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
authors.forename: M
authors.initials: M
authors.lastname: Chawla-Sarkar
authors.forename: S I
authors.initials: SI
authors.lastname: Bae
authors.forename: F J
authors.initials: FJ
authors.lastname: Reu
authors.forename: B S
authors.initials: BS
authors.lastname: Jacobs
authors.forename: D J
authors.initials: DJ
authors.lastname: Lindner
authors.forename: E C
authors.initials: EC
authors.lastname: Borden
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D051023:BH3 Interacting Domain Death Agonist Protein; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002352:Carrier Proteins / Q000378:metabolism; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D019254:Genes, bcl-2 / Q000502:physiology; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008545:Melanoma / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000494:pharmacology*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009363:Neoplasm Proteins; D011506:Proteins / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D000077022:Survivin; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D051636:X-Linked Inhibitor of Apoptosis Protein
chemical_list: D051017:Apoptosis Regulatory Proteins; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; C107489:BIRC5 protein, human; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; D051034:Inhibitor of Apoptosis Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D011506:Proteins; D034741:RNA, Small Interfering; D000077022:Survivin; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; C506433:CASP9 protein, human; D053453:Caspase 9; D020169:Caspases