Downregulation of Bcl-2, FLIP or IAPs (XIAP and survivin) by siRNAs sensitizes resistant melanoma cells to Apo2L/TRAIL-induced apoptosis

Cell Death Differ. 2004 Aug;11(8):915-23. doi: 10.1038/sj.cdd.4401416.

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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Apoptosis Regulatory Proteins
  • BH3 Interacting Domain Death Agonist Protein
  • CASP8 and FADD-Like Apoptosis Regulating Protein
  • Carrier Proteins / metabolism
  • Caspase 9
  • Caspases / metabolism
  • Genes, bcl-2 / physiology
  • Humans
  • Inhibitor of Apoptosis Proteins
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Melanoma / metabolism
  • Membrane Glycoproteins / metabolism
  • Membrane Glycoproteins / pharmacology*
  • Microtubule-Associated Proteins / metabolism*
  • Neoplasm Proteins
  • Proteins / metabolism*
  • RNA, Small Interfering / genetics
  • Survivin
  • TNF-Related Apoptosis-Inducing Ligand
  • Tumor Cells, Cultured
  • Tumor Necrosis Factor-alpha / pharmacology*
  • X-Linked Inhibitor of Apoptosis Protein

Substances

  • Apoptosis Regulatory Proteins
  • BH3 Interacting Domain Death Agonist Protein
  • BID protein, human
  • BIRC5 protein, human
  • CASP8 and FADD-Like Apoptosis Regulating Protein
  • CFLAR protein, human
  • Carrier Proteins
  • Inhibitor of Apoptosis Proteins
  • Intracellular Signaling Peptides and Proteins
  • Membrane Glycoproteins
  • Microtubule-Associated Proteins
  • Neoplasm Proteins
  • Proteins
  • RNA, Small Interfering
  • Survivin
  • TNF-Related Apoptosis-Inducing Ligand
  • TNFSF10 protein, human
  • Tumor Necrosis Factor-alpha
  • X-Linked Inhibitor of Apoptosis Protein
  • XIAP protein, human
  • CASP9 protein, human
  • Caspase 9
  • Caspases