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Analysis of Cell Cycle Position in Mammalian Cells
12:19

Analysis of Cell Cycle Position in Mammalian Cells

Published on: January 21, 2012

Phorbol ester-induced G1 phase arrest selectively mediated by protein kinase Cdelta-dependent induction of p21

Motonori Nakagawa1, Jose Luis Oliva, Devashish Kothapalli

  • 1Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA.

The Journal of Biological Chemistry
|August 2, 2005
PubMed

Insights

Protein Kinase C delta (PKCdelta) triggers G1 cell cycle arrest in lung cancer cells by increasing the cell cycle inhibitor p21. This study reveals PKCdelta

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cancer Research

Background:

  • Protein Kinase C (PKC) isozymes regulate cell proliferation, but their specific roles in cell cycle control are not fully understood.
  • Lung adenocarcinoma cells are a relevant model for studying cell cycle dysregulation in cancer.

Purpose of the Study:

  • To elucidate the role of PKCdelta in mediating phorbol ester-induced G1 arrest in lung adenocarcinoma cells.
  • To identify the downstream molecular targets of PKCdelta involved in cell cycle regulation.

Main Methods:

  • PKC isozyme depletion using specific inhibitors or RNA interference.
  • Cell cycle progression analysis (e.g., into S phase).
  • Quantitative analysis of cell cycle regulatory proteins (p21, Rb, cyclins) and their mRNA levels.
  • Reporter gene assays to assess promoter activity.

Main Results:

  • PKCdelta activation by phorbol 12-myristate 13-acetate (PMA) induced G1 arrest in lung adenocarcinoma cells.
  • PKCdelta depletion abolished PMA-induced G1 arrest, while PKCalpha depletion did not.
  • PMA treatment up-regulated p21 expression and down-regulated Rb hyperphosphorylation and cyclin A expression, mediated by PKCdelta.
  • PKCdelta was essential for PMA-induced inhibition of cyclin A promoter activity.
  • Knock-down of p21 attenuated the cell cycle inhibitory effects of PKCdelta.

Conclusions:

  • PKCdelta plays a critical role in mediating G1 arrest in lung adenocarcinoma cells.
  • PKCdelta controls G1 arrest through the up-regulation of the cell cycle inhibitor p21.
  • These findings highlight the specific downstream mechanisms of PKC isozymes in cell cycle control and cancer proliferation.

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