Silencing of the IKKε gene by siRNA inhibits invasiveness and growth of breast cancer cells.
BACKGROUND
IκB Kinase ε (IKKε) is a member of the IKK family which plays an important role in the activation of nuclear factor-κB (NF-κB). Overexpressed in over 30% of breast cancers, IKKε has been recently identified as a potential breast cancer oncogene. The purpose of this study is to examine the therapeutic potential of IKKε siRNA on human breast cancer cells.


METHODS
Eight siRNAs targeting different regions of the IKKε mRNA were designed, and the silencing effect was screened by quantitative real time RT-PCR. The biological effects of synthetic siRNAs on human breast cancer cells were investigated by examining the cell proliferation, migration, invasion, focus formation, anchorage-independent growth(via soft agar assay), cell cycle arrest, apoptosis (via annexing binding), NF-κB basal level, and NF-κB related gene expressions upon the IKKε silencing.


RESULTS
Silencing of IKKε in human breast cancer cells resulted in decrease of focus formation potential and clonogenicity as well as in vitro cell migration/invasion capabilities. Moreover, knockdown of IKKε suppressed cell proliferation. Cell cycle assay showed that the anti-proliferation effect of IKKε siRNA was mediated by arresting cells in G(0)/G(1) phase, which was caused by down-regulation of cyclin D(1). Furthermore, we demonstrated that silencing of IKKε inhibited the NF-κB basal activity as well as the Bcl-2 expression. Significant apoptosis was not observed in breast cancer cells upon the silencing of IKKε. The present study provided the first evidence that silencing IKKε using synthetic siRNA could inhibit the invasiveness properties and proliferation of breast cancer cells.


CONCLUSIONS
Our results suggested that silencing IKKε using synthetic siRNA may offer a novel therapeutic strategy for breast cancer.
Qin
Bin
B
Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 64108, USA.
Cheng
Kun
K
D017209:Apoptosis / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics* / Q000628:therapy*; D059447:Cell Cycle Checkpoints / Q000235:genetics*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D019938:Cyclin D1 / Q000096:biosynthesis / Q000235:genetics; D015536:Down-Regulation; D005260:Female; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics* / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D009361:Neoplasm Invasiveness / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D034622:RNA Interference; D034741:RNA, Small Interfering; D015398:Signal Transduction
D016328:NF-kappa B; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D019938:Cyclin D1; D051550:I-kappa B Kinase