Related Experiment Video

Updated: Aug 23, 2026

Through the Looking Glass: Time-lapse Microscopy and Longitudinal Tracking of Single Cells to Study Anti-cancer Therapeutics
06:00

Through the Looking Glass: Time-lapse Microscopy and Longitudinal Tracking of Single Cells to Study Anti-cancer Therapeutics

Published on: May 14, 2016

[Antiproliferative effect of bcl-2 gene does not concern the control of mitotic events]

A M Neliudova1, A I Brichkina, M P Rukhlova

  • 1Institute of Cytology RAS, St. Petersburg. annanelioudova@hotmail.com

Tsitologiia
|June 25, 2004
PubMed

Insights

Overexpressing Bcl-2 oncogene in cancer cells can arrest the cell cycle at G1/S after DNA damage. However, inhibiting cyclin-dependent kinases (Cdks) with Roscovitine does not cause G1/S arrest but leads to G2/M accumulation and apoptosis.

Area of Science:

  • Cell Biology
  • Molecular Oncology
  • Cancer Research

Background:

  • The interplay between oncogenes (E1A, c-Ha-ras) and anti-apoptotic proteins (Bcl-2) influences cell cycle regulation and response to DNA damage.
  • Understanding how Bcl-2 affects cell cycle checkpoints and apoptosis is crucial for developing targeted cancer therapies.

Purpose of the Study:

  • To investigate the role of Bcl-2 in cell cycle arrest at the G1/S boundary in response to DNA damage and serum starvation.
  • To determine the effect of cyclin-dependent kinase (Cdk) inhibition by Roscovitine on cell cycle progression and apoptosis in cells expressing E1A, c-Ha-ras, and Bcl-2.
  • To assess whether Bcl-2 expression can restore the regulation of mitotic events disrupted by oncogene introduction.

Main Methods:

  • Utilized cell lines overexpressing E1A, c-Ha-ras, and Bcl-2 oncogenes.
  • Applied DNA damaging agents and serum starvation to induce cell cycle arrest.
  • Administered Roscovitine to inhibit Cdk activity.
  • Used nocodazole to disrupt microtubule polymerization and study mitotic arrest.
  • Monitored cell cycle progression, Cdk activity, and apoptosis via specific assays.

Main Results:

  • E1A + c-Ha-ras + Bcl-2 transformants arrested at G1/S after DNA damage, with decreased cyclin E-Cdk2 activity.
  • Roscovitine treatment did not induce G1/S arrest but caused G2/M accumulation and apoptosis in these cells.
  • Bcl-2 did not restore normal mitotic event regulation; nocodazole treatment induced polyploidy and apoptosis.
  • Both Roscovitine and nocodazole triggered apoptosis in sensitive and resistant cell lines, irrespective of Bcl-2 expression.

Conclusions:

  • Cdk inhibition by Roscovitine is unlikely to be the primary cause of G1/S arrest after DNA damage in Bcl-2 expressing cells.
  • Bcl-2's antiproliferative effect in E1A + c-Ha-ras transformants is limited to restoring G1/S and G2/M checkpoints, not mitotic regulation.
  • Disruption of cell cycle checkpoints and mitotic events, through Cdk inhibition or microtubule disruption, leads to apoptosis in these oncogene-expressing cells.

More Related Videos

Cell Death Associated with Abnormal Mitosis Observed by Confocal Imaging in Live Cancer Cells15:53

Cell Death Associated with Abnormal Mitosis Observed by Confocal Imaging in Live Cancer Cells

Published on: August 21, 2013

Studying Cell Cycle-regulated Gene Expression by Two Complementary Cell Synchronization Protocols12:02

Studying Cell Cycle-regulated Gene Expression by Two Complementary Cell Synchronization Protocols

Published on: June 6, 2017

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...
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.
Mitogens and the Cell Cycle02:38

Mitogens and the Cell Cycle

Mitogens and their receptors play a crucial role in controlling the progression of the cell cycle. However, the loss of mitogenic control over cell division leads to tumor formation. Therefore, mitogens and mitogen receptors play an important role in cancer research. For instance, the epidermal growth factor (EGF) - a type of mitogen and its transmembrane receptor (EGFR), decides the fate of the cell's proliferation. When EGF binds to EGFR, a member of the ErbB family of tyrosine kinase...
The Intrinsic Apoptotic Pathway01:31

The Intrinsic Apoptotic Pathway

Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...
Molecular Factors Affecting Cell Division01:27

Molecular Factors Affecting Cell Division

Several external and internal factors influence the initiation and inhibition of cell division. For instance, the death of nearby cells or the release of human growth hormone (hGH) promotes cell division. In contrast, lack of hGH or crowding of cells can inhibit cell division.
Several proteins function as internal regulators to ensure each cell cycle stage is completed faithfully before proceeding to the next. Regulator molecules may act directly or influence the activity or production of other...
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...