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Updated: Jun 28, 2026

Techniques to Induce and Quantify Cellular Senescence
06:51

Techniques to Induce and Quantify Cellular Senescence

Published on: May 1, 2017

Growth stimulation leads to cellular senescence when the cell cycle is blocked

Zoya N Demidenko1, Mikhail V Blagosklonny

  • 1Oncotarget, Albany, New York, USA.

Cell Cycle (Georgetown, Tex.)
|October 25, 2008
PubMed

Insights

Cellular senescence requires growth signaling pathways like mTOR activation. Inhibiting mTOR can prevent senescence, while quiescence, a state of low mTOR activity, protects cells from becoming senescent.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Aging Research

Background:

  • Cellular senescence is a state of irreversible growth arrest.
  • The role of growth-promoting pathways in senescence induction remains unclear.
  • Understanding senescence is crucial for aging and cancer research.

Purpose of the Study:

  • To investigate the requirement of growth-promoting pathways for cellular senescence.
  • To determine the role of the target of rapamycin (TOR) pathway in senescence.
  • To differentiate between senescence and quiescence.

Main Methods:

  • Induction of p21 to cause cell cycle arrest in the presence and absence of serum.
  • Treatment with rapamycin to inhibit TOR activity.
  • Assessment of senescent markers: beta-Galactosidase staining, cell hypertrophy, cyclin D1 levels, and TOR activity.
  • Use of doxorubicin (DOX) to induce senescence in normal human cells (WI38 fibroblasts, RPE cells).

Main Results:

  • In serum, p21 induction caused senescence with high TOR activity, cyclin D1, and hypertrophy.
  • Serum starvation or rapamycin inhibited TOR, preventing some senescent markers despite p21-induced arrest.
  • p21-arrested cells in serum lost proliferative potential irreversibly; cells arrested without serum retained it.
  • Quiescence (low TOR) in WI38 and RPE cells was characterized by slim morphology and low cyclin D1.
  • DOX-induced senescence in serum involved high TOR activity; TOR inhibition partially prevented this phenotype.

Conclusions:

  • Growth stimulation coupled with cell cycle arrest is necessary for cellular senescence.
  • The target of rapamycin (TOR) pathway activation is a key component of the senescent phenotype.
  • Quiescence, characterized by inactive TOR, prevents senescence and preserves proliferative capacity.

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