Increased expression of p27Kip1 arrests neuroblastoma cell growth

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Updated: Oct 5, 2026

Analysis of Cell Cycle Position in Mammalian Cells
12:19

Analysis of Cell Cycle Position in Mammalian Cells

Published on: January 21, 2012

T Matsuo1, P Seth, C J Thiele

  • 1Division of Clinical Sciences, National Cancer Institute, Bethesda, Maryland 20892-1928, USA.

Medical and Pediatric Oncology
|July 24, 2001
PubMed
Abstract

Insights

Retinoic acid (RA) treatment downregulates G1 cyclin/cdk activity in neuroblastoma cells by increasing the expression of p27Kip1, a cyclin-dependent kinase inhibitor, leading to G1 cell cycle arrest. This mechanism involves post-transcriptional regulation and is influenced by N-MYC levels.

Area of Science:

  • Molecular Biology
  • Cell Cycle Regulation
  • Cancer Research

Background:

  • Retinoic acid (RA) is a crucial signaling molecule involved in cell differentiation and growth.
  • Neuroblastoma (NB) cells are a pediatric cancer where RA is used therapeutically.
  • Understanding RA's impact on the cell cycle is key to its therapeutic application.

Purpose of the Study:

  • To elucidate the molecular mechanisms by which retinoic acid (RA) influences cell growth.
  • To investigate the role of cell cycle machinery components in RA-mediated effects.
  • To determine how RA affects cyclin-dependent kinase (cdk) activity and expression of cdk inhibitors.

Main Methods:

  • Analysis of cell cycle machinery expression and activity in response to RA treatment.
  • Western blotting to assess protein levels of cyclins, cdks, and cdk inhibitors (p21Cip1, p27Kip1, p15INK4B, p16INK4A).
  • Assessment of hyperphosphorylated Rb and p60N-MYC protein levels.
  • Evaluation of p27 expression in N-MYC transfected cells and using adenoviral vectors.

Main Results:

  • RA treatment led to a complete downregulation of G1 cyclin/cdk activities within 2 days, preceding G1 arrest.
  • Protein levels of G1 cyclin/cdks remained unchanged, but hyperphosphorylated Rb and p60N-MYC decreased.
  • p27Kip1 expression significantly increased within 24 hours of RA treatment, independent of mRNA levels.
  • Increased p27Kip1 correlated with decreased cdk activity and G1 cell cycle accumulation.
  • Overexpression of N-MYC reduced steady-state levels of p27 and its binding to G1 cyclin/cdk complexes.

Conclusions:

  • RA induces G1 cell cycle arrest in neuroblastoma cells primarily through the upregulation of the cdk inhibitor p27Kip1.
  • The increase in p27Kip1 is regulated post-transcriptionally and is influenced by N-MYC levels.
  • Targeting p27Kip1 expression or its interaction with cyclin/cdk complexes represents a potential therapeutic strategy in neuroblastoma.

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