Related Experiment Video

Updated: Jun 10, 2026

Detection and Visualization of DNA Damage-induced Protein Complexes in Suspension Cell Cultures Using the Proximity Ligation Assay
13:10

Detection and Visualization of DNA Damage-induced Protein Complexes in Suspension Cell Cultures Using the Proximity Ligation Assay

Published on: June 9, 2017

S-phase lengthening induced by p16(INK4a) overexpression in malignant cells with wild-type pRb and p53

Wei Wen Chien1, Carine Domenech, Régine Catallo

  • 1Université Claude Bernard Lyon 1, CNRS UMR 5239, ENS-HCL, Faculté de Médecine, Pierre-Bénite, France.

Cell Cycle (Georgetown, Tex.)
|August 13, 2010
PubMed

Insights

The protein p16 INK4a, when overexpressed, lengthens S-phase and causes G1 accumulation in cancer cells. This cell cycle regulation occurs independently of cell type and involves inhibiting cyclin-dependent kinases (CDKs) 4 and 6.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cancer Research

Background:

  • The p16(INK4a) protein typically inhibits cyclin-dependent kinases (CDKs) 4 and 6, arresting the cell cycle at G(0)/G(1).
  • Understanding p16(INK4a)'s precise role in cell cycle regulation is crucial for cancer therapy development.

Purpose of the Study:

  • To investigate the effects of ectopic p16(INK4a) expression on cell cycle progression in human cancer cell lines.
  • To elucidate the molecular mechanisms underlying p16(INK4a)-induced cell cycle arrest.

Main Methods:

  • Ectopic expression of p16(INK4a) in MCF7, U2OS, and U87 cancer cell lines.
  • Flow cytometry for DNA content analysis and BrdU labeling assays.
  • IdU/BrdU double labeling and Western blotting to assess protein levels and phosphorylation.

Main Results:

  • Ectopic p16(INK4a) expression induced S-phase lengthening and G(1) accumulation across different cancer cell lines.
  • p16(INK4a) significantly decreased pRb phosphorylation at Ser-807/811, downregulated CDK2 and CDK1 expression, and reduced Thr/Pro phosphorylation.
  • A non-functional p16 mutant failed to induce S-phase lengthening or inhibit key phosphorylation events, confirming the role of CDK4/6 inhibition.

Conclusions:

  • p16(INK4a) induces S-phase lengthening and cell cycle arrest independently of cellular origin.
  • The mechanism involves inhibiting CDK4/6 activity and downregulating CDK2/CDK1, preventing compensatory kinase activity and halting cell cycle progression.

More Related Videos

Assessment of Global DNA Double-Strand End Resection using BrdU-DNA Labeling coupled with Cell Cycle Discrimination Imaging06:44

Assessment of Global DNA Double-Strand End Resection using BrdU-DNA Labeling coupled with Cell Cycle Discrimination Imaging

Published on: April 28, 2021

Laser Micro-Irradiation to Study DNA Recruitment During S Phase07:11

Laser Micro-Irradiation to Study DNA Recruitment During S Phase

Published on: April 16, 2021

Related Concept Videos

Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
DNA Damage Can Stall the Cell Cycle02:36

DNA Damage Can Stall the Cell Cycle

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
DNA Damage can Stall the Cell Cycle02:36

DNA Damage can Stall the Cell Cycle

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
Negative Regulator Molecules01:23

Negative Regulator Molecules

Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.
Inhibition of Cdk Activity02:34

Inhibition of Cdk Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Restarting Stalled Replication Forks02:37

Restarting Stalled Replication Forks

DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...