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Updated: Aug 10, 2026

Analysis of Cell Cycle Position in Mammalian Cells
12:19

Analysis of Cell Cycle Position in Mammalian Cells

Published on: January 21, 2012

Negative cell cycle regulator 14-3-3sigma stabilizes p27 Kip1 by inhibiting the activity of PKB/Akt

H Yang1, Y Zhang, R Zhao

  • 1Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.

Oncogene
|March 15, 2006
PubMed

Insights

The 14-3-3sigma protein, a cancer marker, halts cell cycle progression by stabilizing p27Kip1 and inactivating Akt. This finding reveals 14-3-3sigma as a potential anticancer agent.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Oncology

Background:

  • 14-3-3sigma (sigma) is a human cancer marker often downregulated in tumors, but its precise function remains unclear.
  • While overexpressed 14-3-3sigma can inhibit cell cycle, its regulatory role concerning p27Kip1 and Akt signaling is not fully elucidated.
  • Protein kinase B/Akt is a key regulator of oncogenic signaling, promoting cell growth by phosphorylating and degrading p27Kip1.

Purpose of the Study:

  • To investigate the mechanism by which 14-3-3sigma influences cell cycle progression.
  • To determine if 14-3-3sigma regulates the cyclin-dependent kinase inhibitor p27Kip1 via the Akt pathway.
  • To explore the potential of 14-3-3sigma as an anticancer agent.

Main Methods:

  • Western blotting to assess protein levels and phosphorylation.
  • Immunofluorescence to determine protein localization (nuclear vs. cytoplasmic).
  • Cell-based assays to evaluate cell cycle arrest, survival, and tumorigenicity.

Main Results:

  • 14-3-3sigma overexpression induced cell cycle arrest, correlating with increased p27Kip1 levels and decreased Akt activity.
  • 14-3-3sigma inhibited Akt-mediated phosphorylation and subsequent degradation of p27Kip1, preventing its nuclear export.
  • 14-3-3sigma suppressed the survival and tumorigenicity of breast cancer cells with activated Akt.
  • Low 14-3-3sigma expression in primary breast cancers correlated with cytoplasmic p27Kip1 localization.

Conclusions:

  • 14-3-3sigma acts as a positive regulator of p27Kip1 by inhibiting Akt signaling, leading to cell cycle arrest.
  • 14-3-3sigma's ability to stabilize p27Kip1 and inhibit Akt highlights its role in tumor suppression.
  • 14-3-3sigma represents a promising target for cancer gene therapy and a potential anticancer agent.

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