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Research Paper
Signal Therapy of Breast Cancers by the HDAC Inhibitor FK228 that Blocks the Activation of PAK1 and Abrogates the Tamoxifen-Resistance
Yumiko Hirokawa, Melissa Arnold, Hidenori Nakajima, John Zalcberg and Hiroshi Maruta
volume 4 | issue 9
september 2005Pages: 956-960
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PAK1, a Rac/CDC42-dependent Ser/Thr kinase, is required for both neurofibromatosis (NF) and RAS transformation in vivo. FK228, a histone deacetylase (HDAC) inhibitor, activates a very specific set of genes such as the tumor suppressor WAF1, an inhibitor of cyclin-dependent kinases (CDKs), and suppresses the growth of these tumors. In addition, this drug down-regulates cyclin D1, which is up-regulated by RAS through PAK1, in breast cancers. In this study, we demonstrate that FK228 at 0.1- 1 nM significantly reduces the kinase activity of PAK1 in these cells, without affecting the protein level of PAK1. Interestingly, estrogen receptor (ER) and PAK1 mutually activate each other in breast cancers. Here we provide an evidence suggesting that breast cancers require PAK1 for their estrogen-dependent growth. Moreover, the treatment with FK228 strongly inhibits the estrogen-dependent growth of human breast cancers (both tamoxifen-sensitive and resistant cell lines) in vivo, suggesting that FK228 and other anti-PAK1 drugs would be useful for the treatment of breast cancers which become resistant to currently used estrogen antagonists such as tamoxifen.
We now provide open access to journal articles published online for one year or more. This article may be downloaded at the following link:
Download PDFIf the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.