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Updated: Jul 18, 2026
Comet Assay as an Indirect Measure of Systemic Oxidative Stress
Published on: May 22, 2015
Comet fluorescence in situ hybridization analysis for oxidative stress-induced DNA damage in colon cancer relevant
Michael Glei1, Anja Schaeferhenrich, Uwe Claussen
1Institute for Nutrition, Dornburger Strasse 25, Friedrich-Schiller-University Jena, 07743 Jena, Germany.
Abstract:
Our objective was to study whether products of oxidative stress, such as hydrogen peroxide (H(2)O(2)), trans-2-hexenal, and 4-hydroxy-2-nonenal (HNE), cause DNA damage in genes, relevant for human colon cancer. For this, total DNA damage was measured in primary human colon cells and colon adenoma cells (LT97) using the single-cell gel electrophoresis assay, known as "Comet Assay." APC, KRAS, and TP53 were marked in the comet images using fluorescence in situ hybridization (Comet FISH). The migration of APC, KRAS, or TP53 signals into the comet tails was quantified and compared to total DNA damage. All three substances were clearly genotoxic for APC, KRAS, and TP53 genes and total DNA in both types of cells. In primary colon cells, TP53 gene was more sensitive toward H(2)O(2), trans-2-hexenal, and HNE than total DNA was. In LT97 cells, the TP53 gene was more sensitive only toward trans-2-hexenal and HNE. APC and KRAS genes were more susceptible than total DNA to both lipid peroxidation products but only in primary colon cells. This suggests genotoxic effects of lipid peroxidation products in APC, KRAS, and TP53 genes. In LT97 cells, TP53 was more susceptible than APC and KRAS toward HNE. Based on the reported gatekeeper properties of TP53, which in colon adenoma is frequently altered to yield carcinoma, this implies that HNE is likely to contribute to cancer progression. This new experimental approach facilitates studies on effects of nutrition-related carcinogens in relevant target genes.
Insights
Oxidative stress products like H2O2, trans-2-hexenal, and HNE cause DNA damage in key colon cancer genes. The TP53 gene is particularly sensitive, suggesting a role in cancer progression.
Area of Science:
- Molecular biology
- Genetics
- Cancer research
Background:
- Oxidative stress and lipid peroxidation products are implicated in cancer development.
- Specific genes like APC, KRAS, and TP53 are critical in colon cancer pathogenesis.
- Understanding genotoxicity mechanisms is crucial for cancer prevention and treatment.
Purpose of the Study:
- To investigate the genotoxic effects of hydrogen peroxide (H2O2), trans-2-hexenal, and 4-hydroxy-2-nonenal (HNE) on critical genes in human colon cells.
- To compare the DNA damage levels in specific genes (APC, KRAS, TP53) versus total DNA.
- To assess the differential sensitivity of these genes to oxidative stress products in primary colon cells and colon adenoma cells (LT97).
Main Methods:
- Utilized the single-cell gel electrophoresis assay (Comet Assay) to measure total DNA damage.
- Employed fluorescence in situ hybridization (Comet FISH) to specifically mark and quantify damage in APC, KRAS, and TP53 genes.
- Analyzed DNA migration in comet tails to assess genotoxicity in primary human colon cells and LT97 colon adenoma cells.
Main Results:
- All three tested substances (H2O2, trans-2-hexenal, HNE) demonstrated clear genotoxicity towards APC, KRAS, and TP53 genes and total DNA in both cell types.
- The TP53 gene showed higher sensitivity to H2O2, trans-2-hexenal, and HNE than total DNA in primary colon cells.
- In LT97 cells, TP53 was more sensitive to trans-2-hexenal and HNE, while APC and KRAS were more susceptible to these lipid peroxidation products in primary cells.
Conclusions:
- Lipid peroxidation products exhibit genotoxic effects on key colon cancer genes (APC, KRAS, TP53).
- The TP53 gene's heightened sensitivity to HNE in colon adenoma cells suggests a potential role in colon cancer progression.
- The developed Comet FISH method offers a valuable tool for studying the impact of nutrition-related carcinogens on specific target genes in cancer research.
