Related Experiment Video
Updated: Aug 30, 2026
Visualizing and Quantifying Endonuclease-Based Site-Specific DNA Damage
Published on: August 21, 2021
A role for DNA mismatch repair in sensing and responding to fluoropyrimidine damage
Mark Meyers1, Arlene Hwang, Mark W Wagner
1Laboratory of Molecular Stress Responses, Department of Radiation Oncology, Case Western Reserve University, Biomedical Research Building 326-East, 2109 Adelbert Road, Cleveland, OH 44106-4942, USA.
Abstract:
The phenomenon of damage tolerance, whereby cells incur DNA lesions that are nonlethal, largely ignored, but highly mutagenic, appears to play a key role in carcinogenesis. Typically, these lesions are generated by alkylation of DNA or incorporation of base analogues. This tolerance is usually a result of the loss of specific DNA repair processes, most often DNA mismatch repair (MMR). The availability of genetically matched MMR-deficient and -corrected cell systems allows dissection of the consequences of this unrepaired damage in carcinogenesis as well as the elucidation of cell cycle checkpoint responses and cell death consequences. Recent data indicate that MMR plays an important role in detecting damage caused by fluorinated pyrimidines (FPs) and represents a repair system that is probably not the primary system for detecting damage caused by these agents, but may be an important system for correcting key mutagenic lesions that could initiate carcinogenesis. In fact, clinical studies have shown that there is no benefit of FP-based adjuvant chemotherapy in colon cancer patients exhibiting microsatellite instability, a hallmark of MMR deficiency. MMR-mediated damage tolerance and futile cycle repair processes are discussed, as well as possible strategies using FPs to exploit these systems for improved anticancer therapy.
Insights
Cells tolerate DNA damage, often ignored but mutagenic, contributing to cancer. DNA mismatch repair (MMR) deficiency allows this, impacting cancer treatment effectiveness, especially with fluorinated pyrimidines (FPs).
Area of Science:
- Molecular Biology
- Cancer Research
- Genetics
Background:
- Cellular damage tolerance, characterized by ignoring non-lethal but mutagenic DNA lesions, is implicated in carcinogenesis.
- These lesions often arise from DNA alkylation or base analogue incorporation.
- Loss of DNA repair processes, particularly DNA mismatch repair (MMR), is a common cause of damage tolerance.
Purpose of the Study:
- To investigate the role of DNA mismatch repair (MMR) in cellular damage tolerance and its implications for carcinogenesis.
- To explore the interaction between MMR and fluorinated pyrimidines (FPs) in DNA damage detection and repair.
- To analyze the impact of MMR deficiency on the efficacy of FP-based chemotherapy.
Main Methods:
- Utilizing genetically matched MMR-deficient and MMR-corrected cell systems.
- Analyzing cell cycle checkpoint responses and cell death pathways.
- Reviewing clinical studies on FP chemotherapy in colon cancer patients with microsatellite instability.
Main Results:
- MMR plays a role in detecting damage caused by fluorinated pyrimidines (FPs), correcting key mutagenic lesions.
- MMR deficiency, indicated by microsatellite instability, correlates with no benefit from FP-based adjuvant chemotherapy in colon cancer.
- MMR-mediated damage tolerance and futile repair cycles contribute to cancer development.
Conclusions:
- MMR is crucial for correcting mutagenic lesions that initiate carcinogenesis, particularly in response to FP-induced DNA damage.
- Understanding MMR's role in damage tolerance can inform strategies for improving anticancer therapies.
- Exploiting MMR-mediated damage tolerance and futile repair processes with FPs may offer novel therapeutic avenues.
Related Concept Videos
01:20Mismatch Repair
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
01:48Mismatch Repair
01:48Mismatch Repair
01:38Nucleotide Excision Repair
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...
01:46Nucleotide Excision Repair
01:46Nucleotide Excision Repair