Volume 97, Issue 8 pp. 729-736
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Fbxw7 contributes to tumor suppression by targeting multiple proteins for ubiquitin-dependent degradation

Yo Fujii

Yo Fujii

Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, and

CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

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Masayoshi Yada

Masayoshi Yada

Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, and

CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

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Masaaki Nishiyama

Masaaki Nishiyama

Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, and

CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

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Takumi Kamura

Takumi Kamura

Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, and

CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

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Hidehisa Takahashi

Hidehisa Takahashi

Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, and

CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

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Ryosuke Tsunematsu

Ryosuke Tsunematsu

Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, and

CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

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Etsuo Susaki

Etsuo Susaki

Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, and

CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

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Tadashi Nakagawa

Tadashi Nakagawa

Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, and

CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

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Akinobu Matsumoto

Akinobu Matsumoto

Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, and

CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

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Keiichi I. Nakayama

Corresponding Author

Keiichi I. Nakayama

Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, and

CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

To whom correspondence should be addressed. E-mail: [email protected]Search for more papers by this author
First published: 04 July 2006
Citations: 57

Abstract

Fbxw7 (also known as Sel-10, hCdc4 or hAgo) is the F-box protein component of a Skp1–Cul1–F-box protein (SCF) ubiquitin ligase. Fbxw7 contributes to the ubiquitin-mediated degradation of cyclin E, c-Myc, Aurora-A, Notch and c-Jun, all of which appear to function as cell-cycle promoters and oncogenic proteins. Loss of Fbxw7 results in elevated expression of its substrates, which may lead to oncogenesis. However, it remains largely unclear which accumulating substrate is most related to cancer development in Fbxw7-mutant cancer cells. In the present study, we examined the abundance of cyclin E, c-Myc and Aurora-A in seven cancer cell lines, which harbor wild-type (three lines) or mutant (four lines) Fbxw7. Although these three substrates accumulated in the Fbxw7-mutant cells, the extent of increase in the expression of these proteins varied in each line. Forced expression of Fbxw7 reduced the levels of cyclin E, c-Myc and Aurora-A in the Fbxw7-mutant cells. In contrast, a decrease in the expression of cyclin E, c-Myc or Aurora-A by RNA interference significantly suppressed the rate of proliferation and anchorage-independent growth of the Fbxw7-mutant cells. These findings thus suggest that the loss of Fbxw7 results in accumulation of cyclin E, c-Myc and Aurora-A, all of which appear to be required for growth promotion of cancer cells. Fbxw7 seems to regulate the levels of multiple targets to suppress cancer development. (Cancer Sci 2006; 97: 729–736)

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