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Yeast As a Chassis for Developing Functional Assays to Study Human P53
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Yeast As a Chassis for Developing Functional Assays to Study Human P53

Published on: August 4, 2019

The permissive effect of p21(Waf1/Cip1) on DNA synthesis is dependent on cell type: effect is absent in p53-inactive

R H Weiss1, C J Randour

  • 1Division of Nephrology, Department of Internal Medicine, University of California, Davis, CA 95616, USA. rhweiss@ucdavis.edu

Cellular Signalling
|July 13, 2000
PubMed

Insights

Cyclin-dependent kinase inhibitors like p21(Waf1/Cip1) can promote cell growth. This study found that p21(Waf1/Cip1)

Area of Science:

  • Cell biology
  • Molecular biology
  • Cancer research

Background:

  • Cyclin-dependent kinase inhibitors (CKI) regulate cell cycle progression.
  • While typically inhibitory, CKIs like p21(Waf1/Cip1) can also permit cell cycle transit.
  • The role of p53 in modulating p21(Waf1/Cip1)'s effect on growth is unclear.

Purpose of the Study:

  • To investigate the impact of p21(Waf1/Cip1) inhibition on cell growth in cells with inactive p53.
  • To determine if p21(Waf1/Cip1)'s permissive growth effects are cell-type dependent.
  • To explore the molecular mechanisms underlying p21(Waf1/Cip1)'s permissive role.

Main Methods:

  • Transfection of human squamous carcinoma A431 cells with antisense p21(Waf1/Cip1) oligodeoxynucleotide.
  • Assessment of p21(Waf1/Cip1) protein transcription and cell growth.
  • Analysis of cyclinD/cdk4 association and Rb hyperphosphorylation.

Main Results:

  • Antisense p21(Waf1/Cip1) oligodeoxynucleotide specifically inhibited p21(Waf1/Cip1) transcription in A431 cells.
  • No significant growth inhibition was observed in A431 cells upon serum or PDGF-BB stimulation after p21(Waf1/Cip1) inhibition.
  • CyclinD/cdk4 association and Rb hyperphosphorylation were not attenuated, indicating an alternative pathway.
  • These findings contrast with observations in vascular smooth muscle (VSM) cells.

Conclusions:

  • The permissive effect of p21(Waf1/Cip1) on cell growth is cell-type specific.
  • Active p53 is likely essential for mediating the growth-promoting role of p21(Waf1/Cip1).
  • Alternative molecular pathways can support cell cycle progression independently of p21(Waf1/Cip1) levels in certain cell types.

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