Stable XIAP knockdown clones of HCT116 colon cancer cells are more sensitive to TRAIL, taxanes and irradiation in vitro

Cancer Chemother Pharmacol. 2009 Jul;64(2):307-16. doi: 10.1007/s00280-008-0872-x. Epub 2008 Nov 26.


Purpose: To develop a model of X-linked inhibitor of apoptosis (XIAP) down regulation in colorectal cancer cell lines. This may be used to determine whether combination strategies have clinical potential.

Methods: A series of clones were developed using short hairpin RNA (shRNA) against XIAP stably expressed in HCT116 cells. XIAP mRNA and protein levels were established by RT-PCR and Immunoblot, respectively. GeneChip microarrays confirmed XIAP knockdown and absence of compensation by other IAP members.

Results: Four XIAP knockdown cell lines show 82-93% reduction in XIAP mRNA and 67-89% reduction in protein when compared to four luciferase control cell lines. XIAP knockdown sensitises cells to rhTRAIL by a factor of 3, to paclitaxel and docetaxel by a factor of >2 and, to a lesser extent, radiotherapy (20% enhancement).

Conclusions: Clinical trials with XIAP antisense continue, and these data suggest combination studies with agents such as rhTRAIL and taxanes should be undertaken.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caspases / metabolism
  • Cell Proliferation / drug effects
  • Cell Proliferation / radiation effects
  • Colonic Neoplasms / drug therapy*
  • Colonic Neoplasms / genetics
  • Colonic Neoplasms / radiotherapy*
  • Flow Cytometry
  • Gamma Rays
  • Gene Expression Profiling
  • Gene Knockdown Techniques
  • Humans
  • Immunoblotting
  • In Vitro Techniques
  • Mice
  • Mice, Nude
  • Oligonucleotide Array Sequence Analysis
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / pharmacology
  • Reverse Transcriptase Polymerase Chain Reaction
  • TNF-Related Apoptosis-Inducing Ligand / pharmacology*
  • Taxoids / pharmacology*
  • Tumor Cells, Cultured
  • X-Linked Inhibitor of Apoptosis Protein / genetics*
  • Xenograft Model Antitumor Assays


  • RNA, Messenger
  • RNA, Small Interfering
  • TNF-Related Apoptosis-Inducing Ligand
  • TNFSF10 protein, human
  • Taxoids
  • X-Linked Inhibitor of Apoptosis Protein
  • XIAP protein, human
  • Caspases