TY - JOUR
T1 - Transforming growth factor-β suppresses the ability of ski to inhibit tumor metastasis by inducing its degradation
AU - Le Scolan, Erwan
AU - Zhu, Qingwei
AU - Wang, Long
AU - Bandyopadhyay, Abhik
AU - Javelaud, Delphine
AU - Mauviel, Alain
AU - Sun, Luzhe
AU - Luo, Kunxin
PY - 2008/5/1
Y1 - 2008/5/1
N2 - c-Ski is an important corepressor of transforming growth factor-β (TGF-β) signaling through its ability to bind to and repress the activity of the Smad proteins. It was initially identified as an oncogene that promotes anchorage-independent growth of chicken and quail embryo fibroblasts when overexpressed. Although increased Ski expression is detected in many human cancer cells, the roles of Ski in mammalian carcinogenesis have yet to be defined. Here, we report that reducing Ski expression in breast and lung cancer cells does not affect tumor growth but enhances tumor metastasis in vivo. Thus, in these cells, Ski plays an antitumorigenic role. We also showed that TGF-β, a cytokine that is often highly expressed in metastatic tumors, induces Ski degradation through the ubiquitin-dependent proteasome in malignant human cancer cells. On TGF-β treatment, the E3 ubiquitin ligase Arkadia mediates degradation of Ski in a Smad-dependent manner. Although Arkadia interacts with Ski in the absence of TGF-β, binding of phosphorylated Smad2 or Smad3 to Ski is required to induce efficient degradation of Ski by Arkadia. Our results suggest that the ability of TGF-β to induce degradation of Ski could be an additional mechanism contributing to its protumorigenic activity.
AB - c-Ski is an important corepressor of transforming growth factor-β (TGF-β) signaling through its ability to bind to and repress the activity of the Smad proteins. It was initially identified as an oncogene that promotes anchorage-independent growth of chicken and quail embryo fibroblasts when overexpressed. Although increased Ski expression is detected in many human cancer cells, the roles of Ski in mammalian carcinogenesis have yet to be defined. Here, we report that reducing Ski expression in breast and lung cancer cells does not affect tumor growth but enhances tumor metastasis in vivo. Thus, in these cells, Ski plays an antitumorigenic role. We also showed that TGF-β, a cytokine that is often highly expressed in metastatic tumors, induces Ski degradation through the ubiquitin-dependent proteasome in malignant human cancer cells. On TGF-β treatment, the E3 ubiquitin ligase Arkadia mediates degradation of Ski in a Smad-dependent manner. Although Arkadia interacts with Ski in the absence of TGF-β, binding of phosphorylated Smad2 or Smad3 to Ski is required to induce efficient degradation of Ski by Arkadia. Our results suggest that the ability of TGF-β to induce degradation of Ski could be an additional mechanism contributing to its protumorigenic activity.
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U2 - 10.1158/0008-5472.CAN-07-6793
DO - 10.1158/0008-5472.CAN-07-6793
M3 - Article
C2 - 18451154
AN - SCOPUS:44849143723
SN - 0008-5472
VL - 68
SP - 3277
EP - 3285
JO - Cancer Research
JF - Cancer Research
IS - 9
ER -