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CDK inhibitor p57 (Kip2) is negatively regulated by COP9 signalosome subunit 6

Bo Chen1, Ruiying Zhao, Chun-Hui Su

  • 1Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA. chbyxl@163.com

Cell Cycle (Georgetown, Tex.)
|November 29, 2012
PubMed

Insights

COP9 signalosome subunit 6 (CSN6) negatively regulates p57 (Kip2) by promoting its degradation. High CSN6 expression correlates with poor patient survival, suggesting CSN6 drives cancer growth by reducing p57 levels.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Oncology

Background:

  • The COP9 signalosome complex (CSN) regulates protein stability and gene expression.
  • CSN subunit 6 (CSN6) is implicated in cell proliferation and apoptosis.
  • The precise targets and regulatory roles of CSN6 remain incompletely understood.

Purpose of the Study:

  • To identify novel targets of CSN6.
  • To elucidate the regulatory mechanism of CSN6 on its targets.
  • To investigate the role of CSN6-target interaction in cancer progression.

Main Methods:

  • Co-immunoprecipitation assays to detect protein interactions.
  • Western blotting to assess protein expression and stability.
  • Ubiquitination assays to study protein degradation pathways.
  • Kaplan-Meier survival analysis on clinical tumor samples.

Main Results:

  • p57 (Kip2) was identified as a novel target of CSN6.
  • CSN6 negatively regulates p57 (Kip2) expression by promoting its Skp2-mediated ubiquitination and degradation.
  • CSN6 overexpression leads to decreased p57 (Kip2) levels, promoting cell growth, cell cycle deregulation, and transformation.
  • High CSN6 expression or low p57 (Kip2) expression is significantly associated with poor patient survival in tumors.

Conclusions:

  • CSN6 acts as a critical negative regulator of p57 (Kip2).
  • The CSN6-p57 (Kip2) axis plays a significant role in promoting cancer cell growth and progression.
  • CSN6 represents a potential therapeutic target in cancers characterized by its overexpression and subsequent p57 (Kip2) downregulation.

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