Stable XIAP knockdown clones of HCT116 colon cancer cells are more sensitive to TRAIL, taxanes and irradiation in vitro
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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.
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.
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).
Clinical trials with XIAP antisense continue, and these data suggest combination studies with agents such as rhTRAIL and taxanes should be undertaken.
KeywordsXIAP HCT116 TRAIL Radiotherapy Paclitaxel Docetaxel Microarray
AMP-activated protein kinase
Cellular inhibitor of apoptosis protein 1
Cellular inhibitor of apoptosis protein 2
Inhibitor of apoptosis protein
Non-small cell lung cancer
Neuronal apoptosis inhibitor protein
Robust multichip average
Recombinant human TNF related apoptosis inducing ligand
Real time polymerase chain reaction
Short hairpin RNA
X-linked inhibitor of apoptosis protein
The authors would like to thank Michael Dodds and Susan Alexander for technical assistance, Aegera Therapeutics Inc for provision of the shRNA constructs and the Cancer Research UK GeneChip microarray service based in the Paterson Institute, University of Manchester for processing the microarray samples.
Conflict of interest statement
K Connolly was funded by Cancer Research UK (Grant number C96/A4743) and her salary was supported in part by Aegera Therapeutics Inc. The Edinburgh Cancer Research Centre received clinical trial support for the Phase I study AEG35156 (XIAP antisense) from Aegera Therapeutics Inc.
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