Display Settings:

Format

Send to:

Choose Destination
We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
J Biol Chem. 2003 Dec 12;278(50):49795-805. Epub 2003 Oct 3.

FoxO3a transcriptional regulation of Bim controls apoptosis in paclitaxel-treated breast cancer cell lines.

Author information

  • 1Cancer Research-UK Laboratories, Department of Cancer Medicine, Medical Research Council Cyclotron Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, United Kingdom.

Abstract

Paclitaxel is used to treat breast cancers, but the mechanisms by which it induces apoptosis are poorly understood. Consequently, we have studied the role of the FoxO transcription factors in determining cellular response to paclitaxel. Western blotting revealed that in a panel of nine breast cancer cell lines expression of FoxO1a and FoxO3a correlated with the expression of the pro-apoptotic FoxO target Bim, which was associated with paclitaxel-induced apoptosis. In MCF-7 cells, which were paclitaxel-sensitive, the already high basal levels of FoxO3a and Bim protein increased dramatically after drug treatment, as did Bim mRNA, which correlated with apoptosis induction. This was not observed in MDA-231 cells, which expressed low levels of FoxOs and Bim. Gene reporter experiments demonstrated that in MCF-7 cells maximal induction of Bim promoter was dependent on a FoxO binding site, suggesting that FoxO3a is responsible for the transcriptional up-regulation of Bim. Gene silencing experiments showed that small interference RNA (siRNA) specific for FoxO3a reduced the levels of FoxO3a and Bim protein as well as inhibited apoptosis in paclitaxel-treated MCF-7 cells. Furthermore, siRNA specific for Bim reduced the levels of Bim protein and inhibited apoptosis in paclitaxel-treated MCF-7 cells. This is the first demonstration that up-regulation of FoxO3a by paclitaxel can result in increased levels of Bim mRNA and protein, which can be a direct cause of apoptosis in breast cancer cells.

PMID:
14527951
[PubMed - indexed for MEDLINE]
Free full text

LinkOut - more resources

Full Text Sources

Other Literature Sources

Medical

Molecular Biology Databases

PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for HighWire
    Loading ...
    Write to the Help Desk