Details

Autor(en) / Beteiligte

• Miller, Anna V
• Hicks, Mark A
• Nakajima, Wataru
• Richardson, Amanda C
• Windle, Jolene J
• Harada, Hisashi
• Gibson, Spencer B.

Titel

Paclitaxel-induced apoptosis is BAK-dependent, but BAX and BIM-independent in breast tumor

Ist Teil von

• PloS one, 2013-04, Vol.8 (4), p.e60685-e60685

Ort / Verlag

United States: Public Library of Science

Erscheinungsjahr

2013

Quelle

MEDLINE

Beschreibungen/Notizen

• Paclitaxel (Taxol)-induced cell death requires the intrinsic cell death pathway, but the specific participants and the precise mechanisms are poorly understood. Previous studies indicate that a BH3-only protein BIM (BCL-2 Interacting Mediator of cell death) plays a role in paclitaxel-induced apoptosis. We show here that BIM is dispensable in apoptosis with paclitaxel treatment using bim(-/-) MEFs (mouse embryonic fibroblasts), the bim(-/-) mouse breast tumor model, and shRNA-mediated down-regulation of BIM in human breast cancer cells. In contrast, both bak (-/-) MEFs and human breast cancer cells in which BAK was down-regulated by shRNA were more resistant to paclitaxel. However, paclitaxel sensitivity was not affected in bax(-/-) MEFs or in human breast cancer cells in which BAX was down-regulated, suggesting that paclitaxel-induced apoptosis is BAK-dependent, but BAX-independent. In human breast cancer cells, paclitaxel treatment resulted in MCL-1 degradation which was prevented by a proteasome inhibitor, MG132. A Cdk inhibitor, roscovitine, blocked paclitaxel-induced MCL-1 degradation and apoptosis, suggesting that Cdk activation at mitotic arrest could induce subsequent MCL-1 degradation in a proteasome-dependent manner. BAK was associated with MCL-1 in untreated cells and became activated in concert with loss of MCL-1 expression and its release from the complex. Our data suggest that BAK is the mediator of paclitaxel-induced apoptosis and could be an alternative target for overcoming paclitaxel resistance.