Related Experiment Video

Updated: Jul 16, 2026

Detection of DNA Breaks in Dividing Human Cells by Neutral Comet Assay
05:55

Detection of DNA Breaks in Dividing Human Cells by Neutral Comet Assay

Published on: August 23, 2024

XRCC3 depletion induces spontaneous DNA breaks and p53-dependent cell death

Martin Loignon1, Lilian Amrein, Michael Dunn

  • 1Oncology Department, MCETC, and Lady Davis Institute for Medical Research of the Sir Mortimer B. Davis Jewish General Hospital, McGill University, Montréal, Québec, Canada.

Cell Cycle (Georgetown, Tex.)
|March 14, 2007
PubMed

Insights

The DNA repair protein XRCC3 (X-ray repair cross complementing protein 3) is vital for breast cancer cell proliferation. Its depletion causes DNA breaks and triggers p53-dependent cell death.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • XRCC3 (X-ray repair cross complementing protein 3) plays a key role in repairing DNA breaks via homologous recombination in vertebrate cells.
  • Its function in response to spontaneous DNA breaks is less understood.

Purpose of the Study:

  • To investigate the role of XRCC3 in the proliferation and DNA damage response of MCF7 breast cancer cells.
  • To elucidate the cell death pathways activated by XRCC3 depletion.

Main Methods:

  • Small interfering RNA (siRNA) was used to deplete XRCC3 in MCF7 cells.
  • Comet assays were performed to detect DNA breaks.
  • Cell cycle analysis and gammaH2AX expression were assessed.
  • p53 knockdown was used to study its role in cell death.

Main Results:

  • XRCC3 depletion inhibited MCF7 cell proliferation and caused accumulation of DNA breaks, particularly in S and G2/M phases.
  • Increased gammaH2AX expression indicated replication-dependent DNA damage and deficient homologous recombination.
  • p53 knockdown rendered cells more resistant to XRCC3 depletion-induced death.

Conclusions:

  • XRCC3 is essential for MCF7 breast cancer cell proliferation.
  • Reduced XRCC3 levels lead to DNA breaks and activate p53-dependent cell death pathways.

More Related Videos

Application of Laser Micro-irradiation for Examination of Single and Double Strand Break Repair in Mammalian Cells08:18

Application of Laser Micro-irradiation for Examination of Single and Double Strand Break Repair in Mammalian Cells

Published on: September 5, 2017

Laser Microirradiation to Study In Vivo Cellular Responses to Simple and Complex DNA Damage10:44

Laser Microirradiation to Study In Vivo Cellular Responses to Simple and Complex DNA Damage

Published on: January 31, 2018

Related Concept Videos

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...
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.
Nucleotide Excision Repair01:38

Nucleotide Excision Repair

DNA Distortion and Damage
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
Nucleotide Excision Repair01:08

Nucleotide Excision Repair

Overview