Letter abstract
Nature Chemical Biology 3, 570 - 575 (2007)
Published online: 22 July 2007 | doi:10.1038/nchembio.2007.16
Splicing factor SF3b as a target of the antitumor natural product pladienolide
Yoshihiko Kotake1, Koji Sagane1, Takashi Owa1, Yuko Mimori-Kiyosue2, Hajime Shimizu1, Mai Uesugi1, Yasushi Ishihama1,3, Masao Iwata1 & Yoshiharu Mizui1
Pladienolide is a naturally occurring antitumor macrolide that was discovered by using a cell-based reporter gene expression assay controlled by the human vascular endothelial growth factor promoter1, 2. Despite the unique mechanisms of action3 and prominent antitumor activities of pladienolides B and D in diverse in vitro and in vivo systems3, their target protein has remained unclear. We used 3H-labeled, fluorescence-tagged and photoaffinity/biotin (PB)-tagged 'chemical probes' to identify a 140-kDa protein in splicing factor SF3b as the binding target of pladienolide. Immunoblotting of an enhanced green fluorescent protein fusion protein of SF3b subunit 3 (SAP130) revealed direct interaction between the PB probe and SAP130. The binding affinities of pladienolide derivatives to the SF3b complex were highly correlated with their inhibitory activities against reporter gene expression and cell proliferation. Furthermore, pladienolide B impaired in vivo splicing in a dose-dependent manner. Our results demonstrate that the SF3b complex is a pharmacologically relevant protein target of pladienolide and suggest that this splicing factor is a potential antitumor drug target.
- Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan.
- KAN Research Institute Inc., 6-7-3 Minatojimaminami-machi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
- Present address: Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata 997-0017, Japan.
Correspondence to: Yoshiharu Mizui1 e-mail: y-mizui@hhc.eisai.co.jp
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