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Updated: Jun 12, 2026
A High-Throughput Comet Assay Approach for Assessing Cellular DNA Damage
Published on: May 10, 2022
N-acetyl-cysteine protects against DNA damage associated with lead toxicity in HepG2 cells
Clement G Yedjou1, Christine K Tchounwou, Samuel Haile
1Cellomics and Toxicogenomics Research Laboratory, RCMI-Center for Environmental Health, College of Science, Engineering and Technology, Jackson State University, Jackson, Mississippi 39217-0002, USA. clement.yedjou@jsums.edu
Abstract:
Lead toxicity has been associated with its ability to interact and damage DNA. However, its molecular mechanisms of action are not fully understood. In vitro studies in our laboratory indicated that lead nitrate (PbNO3) induces cytotoxicity and oxidative stress to human liver carcinoma (HepG2) cells in a dose-dependent manner. In this research, we hypothesized that n-acetyl-cysteine (NAC), a known antioxidant compound, affords protection against lead-induced cell death associated with genotoxic damage. To test this hypothesis, HepG2 cells were treated either with a physiologic dose of NAC, NAC plus PbNO3, or PbNO3 alone, followed by incubation in humidified 5% CO2 incubator at 37 degrees C for 48 hr. The cell viability was determined by trypan blue exclusion test. The degree of DNA damage was detected by micro gel electrophoresis (comet) assay. Our results showed that lead exposure induces a substantial cytotoxicity as well as a significant genotoxicity to HepG2 cells. However, co-treatment with a physiologic dose (500 microM) of NAC slightly increases cell viability, and significantly reduced (P < .05) the degree of DNA damage. Hence, NAC treatment may be a promising therapeutic candidate for chemoprevention against lead toxicity, based on its ability to scavenge free radicals.
Insights
N-acetyl-cysteine (NAC) may protect against lead toxicity. This study found NAC reduced lead-induced DNA damage and improved cell viability in liver cells, suggesting its potential for preventing lead poisoning.
Area of Science:
- Toxicology
- Cell Biology
- Biochemistry
Background:
- Lead toxicity is a significant health concern, with known DNA damaging capabilities.
- The precise molecular mechanisms underlying lead's genotoxicity remain incompletely understood.
- Lead nitrate (PbNO3) exposure in vitro demonstrably causes cytotoxicity and oxidative stress in HepG2 cells.
Purpose of the Study:
- To investigate the protective effects of n-acetyl-cysteine (NAC) against lead-induced cytotoxicity and genotoxicity in human liver carcinoma (HepG2) cells.
- To determine if NAC can mitigate DNA damage caused by lead exposure.
- To evaluate NAC as a potential chemopreventive agent against lead toxicity.
Main Methods:
- HepG2 cells were treated with physiological doses of n-acetyl-cysteine (NAC), lead nitrate (PbNO3), or a combination of both.
- Cell viability was assessed using the trypan blue exclusion test.
- DNA damage was quantified using the micro gel electrophoresis (comet) assay.
Main Results:
- Lead exposure significantly increased cytotoxicity and genotoxicity in HepG2 cells.
- Co-treatment with NAC (500 microM) resulted in a slight increase in cell viability.
- NAC significantly reduced the level of DNA damage induced by lead (P < .05).
Conclusions:
- N-acetyl-cysteine (NAC) demonstrates protective effects against lead-induced cytotoxicity and genotoxicity in HepG2 cells.
- NAC's antioxidant properties, specifically its free radical scavenging ability, contribute to mitigating lead's harmful effects.
- NAC shows promise as a therapeutic candidate for chemoprevention of lead toxicity.
