Stable XIAP knockdown clones of HCT116 colon cancer cells are more sensitive to TRAIL, taxanes and irradiation in vitro.
OBJECTIVE
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.
Connolly
Kate
K
University of Edinburgh Cancer Research Centre, Crewe Road South, Edinburgh, EH4 2XR, UK. kateconnolly@doctors.org.uk
Mitter
Richard
R
Muir
Morwenna
M
Jodrell
Duncan
D
Guichard
Sylvie
S
D000818:Animals; D020169:Caspases / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000532:radiotherapy*; D005434:Flow Cytometry; D005720:Gamma Rays; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D006801:Humans; D015151:Immunoblotting; D066298:In Vitro Techniques; D051379:Mice; D008819:Mice, Nude; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D043823:Taxoids / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000235:genetics*; D023041:Xenograft Model Antitumor Assays
D012333:RNA, Messenger; D034741:RNA, Small Interfering; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D043823:Taxoids; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D020169:Caspases