HER2-Akt signaling in regulating COP9 signalsome subunit 6 and p53

作者：Xue Yuwen; Chen Jian; Choi Hyun Ho; Phan Liem; Chou Ping Chieh; Zhao Ruiying; Yang Huiling; Santiago Janice; Liu Mo; Yeung Giselle E; Yeung Sai Ching J; Lee Mong Hong^*

来源：Cell Cycle, 2012, 11(22): 4181-4190.

DOI：10.4161/cc.22413

• Akt
• CSN6
• cell cycle
• HER2
• p53

HER2/neu oncogene is frequently overexpressed in various types of cancer, and the (PI3K)-Akt signaling pathway is often activated in HER2-overexpressing cancer cells. CSN6, subunit 6 of the COP9 signalosome complex, is pivotal in regulating MDM2 to destabilize p53, but its upstream regulators remain unclear. Here we show that the HER2-Akt axis is linked to CSN6 regulation, and that Akt is a positive regulator of CSN6. Ectopic expression of Akt can increase the expression of CSN6; accordingly, Akt inhibition leads to CSN6 destabilization. Mechanistic studies show that Akt causes CSN6 phosphorylation at Ser 60, which, in turn, reduces ubiquitin-mediated protein degradation of CSN6. Significantly, Akt%26apos;s positive impact on CSN6 elevation translates into p53 degradation, potentiating transformational activity and increasing DNA damage. Akt inhibition can attenuate these defects caused by CSN6. These data suggest that Akt is an important positive regulator of CSN6, and that activation of Akt in many types of cancer could lead to abnormal elevation of CSN6 and result in downregulated p53 and increased DNA damage, which promotes cancer cell growth.

• 出版日期2012-11-15
• 单位山东大学