Predominant Bcl-XL knockdown disables antiapoptotic mechanisms: tumor necrosis factor-related apoptosis-inducing ligand-based triple chemotherapy overcomes chemoresistance in pancreatic cancer cells in vitro

Cancer Res. 2005 Mar 15;65(6):2344-52. doi: 10.1158/0008-5472.CAN-04-3502.


Pancreatic cancer is lethal because of its invasiveness, rapid progression, and profound resistance to chemotherapy and radiation therapy. To identify the molecular mechanisms underlying this, we have examined the expression and potency of three major death receptors: tumor necrosis factor receptor (TNF-R), TNF-related apoptosis-inducing ligand receptor (TRAIL-R), and Fas in mediating cytotoxicity in four invasive pancreatic cancer cell lines. We have analyzed the expression of major antiapoptotic factors, cell cycle regulators and death receptor decoys (DcR) in comparison with normal pancreas tissues and five other human malignant tumor cell lines. We have found that different pancreatic cancer cell lines coexpress high-level TRAIL-R, Fas, and TNF-R1 but are strongly resistant to apoptosis triggered by the death receptors. DcR2 and DcR3 overexpression may partly contribute to the resistance of pancreatic cancer cells to TRAIL-R- and Fas-mediated cytotoxicity. Bcl-XL and Bcl-2 are predominantly overexpressed in pancreatic cancer cell lines, respectively. Bcl-XL is also predominantly overexpressed in prostate, colorectal, and intestinal cancer cells. The knockdown of the predominant Bcl-XL overexpression significantly reduces the viability of pancreatic cancer cells to TNFalpha- and TRAIL-mediated apoptosis by sublethal-dose single and combined antitumor drugs, including geldanamycin, PS-341, Trichostatin A, and doxorubicine. Geldanamyin and PS-341 synergistically block NFkappaB activation, suppress Akt/PKB pathway, and down-regulate Bcl-XL, Bcl-2, cIAP-1, and cyclin D1 expression. This combined regimen dramatically enhances TRAIL cytotoxic effects and breaks through chemoresistance. Bcl-XL plays a vital role in pancreatic cancer chemoresistance. Geldanamycin, PS-341, and TRAIL triple combination may be a novel therapeutic strategy for pancreatic cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Combined Chemotherapy Protocols / pharmacology*
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Apoptosis Regulatory Proteins
  • Benzoquinones
  • Boronic Acids / administration & dosage
  • Boronic Acids / pharmacology
  • Bortezomib
  • Cell Line, Tumor
  • Doxorubicin / administration & dosage
  • Doxorubicin / pharmacology
  • Drug Synergism
  • Gene Expression Regulation, Neoplastic
  • Gene Silencing
  • HSP90 Heat-Shock Proteins / metabolism
  • Humans
  • Hydroxamic Acids / administration & dosage
  • Hydroxamic Acids / pharmacology
  • Lactams, Macrocyclic
  • Membrane Glycoproteins
  • Pancreatic Neoplasms / drug therapy*
  • Pancreatic Neoplasms / genetics
  • Pancreatic Neoplasms / metabolism
  • Pancreatic Neoplasms / pathology*
  • Proto-Oncogene Proteins c-bcl-2 / biosynthesis
  • Proto-Oncogene Proteins c-bcl-2 / deficiency*
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Pyrazines / administration & dosage
  • Pyrazines / pharmacology
  • Quinones / administration & dosage
  • Quinones / pharmacology
  • TNF-Related Apoptosis-Inducing Ligand
  • Tumor Necrosis Factor-alpha / pharmacology*
  • bcl-X Protein


  • Apoptosis Regulatory Proteins
  • BCL2L1 protein, human
  • Benzoquinones
  • Boronic Acids
  • HSP90 Heat-Shock Proteins
  • Hydroxamic Acids
  • Lactams, Macrocyclic
  • Membrane Glycoproteins
  • Proto-Oncogene Proteins c-bcl-2
  • Pyrazines
  • Quinones
  • TNF-Related Apoptosis-Inducing Ligand
  • TNFSF10 protein, human
  • Tumor Necrosis Factor-alpha
  • bcl-X Protein
  • trichostatin A
  • Bortezomib
  • Doxorubicin
  • geldanamycin