Comet assay in neural cells as a tool to monitor DNA damage induced by chemical or physical factors relevant to environmental and occupational exposure

Electrochemical response mechanism of DNA damaged cells: DNA damage repair and purine metabolism activation

In modern society, due to the sharp increase in pollutants that cause DNA damage, there is a growing demand for innovative detection techniques and biomarkers. In this paper, the electrochemical behavior of HepG2 cells exposed to CdCl2 was investigated, and the electrochemical response mechanism of DNA damage was identified by exploring the correlation between the DNA damage response and purine metabolism. Western blot analysis revealed that the expression levels of ATM and Ku70 increased at 0.3 μM CdCl2, indicating a DNA damage response and activation of DNA repair processes. Simultaneously, elevated expression levels of PRPP aminotransferase, HPRT, and XOD were observed, leading to an increase in intracellular purine levels and electrochemical signals. The expression of Ku70 peaked at 0.5 μM CdCl2, indicating the highest DNA repair activity. The expression profiles of these purine metabolism proteins mirrored those of Ku70, suggesting a strong correlation between the activation of purine metabolism and DNA damage repair. Consistently, intracellular purine levels exhibited a similar trend, leading to corresponding changes in electrochemical signals. In summary, electrochemical using intracellular purines as biomarkers has the potential to emerge as a novel method for detecting early DNA damage.

The effects of ketamine on viability, primary DNA damage, and oxidative stress parameters in HepG2 and SH-SY5Y cells

Ketamine is a dissociative anaesthetic used to induce general anaesthesia in humans and laboratory animals. Due to its hallucinogenic and dissociative effects, it is also used as a recreational drug. Anaesthetic agents can cause toxic effects at the cellular level and affect cell survival, induce DNA damage, and cause oxidant/antioxidant imbalance. The aim of this study was to explore these possible adverse effects of ketamine on hepatocellular HepG2 and neuroblastoma SH-SY5Y cells after 24-hour exposure to a concentration range covering concentrations used in analgesia, drug abuse, and anaesthesia (0.39, 1.56, and 6.25 µmol/L, respectively). At these concentrations ketamine had relatively low toxic outcomes, as it lowered HepG2 and SH-SY5Y cell viability up to 30 %, and low, potentially repairable DNA damage. Interestingly, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and glutathione (GSH) remained unchanged in both cell lines. On the other hand, oxidative stress markers [superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT)] pointed to ketamine-induced oxidant/antioxidant imbalance.

Measuring DNA modifications with the comet assay: a compendium of protocols

The comet assay is a versatile method to detect nuclear DNA damage in individual eukaryotic cells, from yeast to human. The types of damage detected encompass DNA strand breaks and alkali-labile sites (e.g., apurinic/apyrimidinic sites), alkylated and oxidized nucleobases, DNA-DNA crosslinks, UV-induced cyclobutane pyrimidine dimers and some chemically induced DNA adducts. Depending on the specimen type, there are important modifications to the comet assay protocol to avoid the formation of additional DNA damage during the processing of samples and to ensure sufficient sensitivity to detect differences in damage levels between sample groups. Various applications of the comet assay have been validated by research groups in academia, industry and regulatory agencies, and its strengths are highlighted by the adoption of the comet assay as an in vivo test for genotoxicity in animal organs by the Organisation for Economic Co-operation and Development. The present document includes a series of consensus protocols that describe the application of the comet assay to a wide variety of cell types, species and types of DNA damage, thereby demonstrating its versatility.

Cytotoxic, genotoxic, and oxidative stress-related effects of lysergic acid diethylamide (LSD) and phencyclidine (PCP) in the human neuroblastoma SH-SY5Y cell line

Lysergic acid diethylamide (LSD) is a classic hallucinogen, widely abused for decades, while phencyclidine (PCP) has increased in popularity in recent years, especially among the adolescents. Very little is known about the general toxicity of these compounds, especially about their possible neurotoxic effects at the cell level. The aim of this study was to address these gaps by assessing the toxic effects of 24-hour exposure to LSD and PCP in the concentration range of 0.39–100 μmol/L in the human neuroblastoma SH-SY5Y cell line. After cell viability was established, cells treated with concentrations that reduced their viability up to 30 % were further subjected to the alkaline comet assay and biochemical assays that enable estimation of oxidative stress-related effects. Treatment with LSD at 6.25 μmol/L and with PCP at 3.13 μmol/L resulted with 88.06±2.05 and 84.17±3.19 % of viable cells, respectively, and led to a significant increase in primary DNA damage compared to negative control. LSD also caused a significant increase in malondialdehyde level, reactive oxygen species (ROS) production, and glutathione (GSH) level, PCP significantly increased ROS but lowered GSH compared to control. Treatment with LSD significantly increased the activities of all antioxidant enzymes, while PCP treatment significantly increased superoxide dismutase (SOD) and glutathione peroxidase (GPx) but decreased catalase (CAT) activity compared to control. Our findings suggest that LSD has a greater DNA damaging potential and stronger oxidative activity than PCP in SH-SY5Y cells.

In Vitro Magnetic Techniques for Investigating Cancer Progression

Worldwide, there are currently around 18.1 million new cancer cases and 9.6 million cancer deaths yearly. Although cancer diagnosis and treatment has improved greatly in the past several decades, a complete understanding of the complex interactions between cancer cells and the tumor microenvironment during primary tumor growth and metastatic expansion is still lacking. Several aspects of the metastatic cascade require in vitro investigation. This is because in vitro work allows for a reduced number of variables and an ability to gather real-time data of cell responses to precise stimuli, decoupling the complex environment surrounding in vivo experimentation. Breakthroughs in our understanding of cancer biology and mechanics through in vitro assays can lead to better-designed ex vivo precision medicine platforms and clinical therapeutics. Multiple techniques have been developed to imitate cancer cells in their primary or metastatic environments, such as spheroids in suspension, microfluidic systems, 3D bioprinting, and hydrogel embedding. Recently, magnetic-based in vitro platforms have been developed to improve the reproducibility of the cell geometries created, precisely move magnetized cell aggregates or fabricated scaffolding, and incorporate static or dynamic loading into the cell or its culture environment. Here, we will review the latest magnetic techniques utilized in these in vitro environments to improve our understanding of cancer cell interactions throughout the various stages of the metastatic cascade.

Impact of single nucleotide polymorphisms in the OGG1 and XRCC1 genes on modulation of DNA damage in pesticide-exposed agricultural workers in Punjab, North-West India

Pesticide-induced DNA damage is primarily repaired by base excision repair (BER) pathway. However, polymorphism in DNA repair genes may modulate individual's DNA repair capacity (DRC) leading to increased genotoxicity and adverse health effects. Our first study in North-West Indian population aimed to evaluate the impact of OGG1 rs1052133 (Ser326Cys; C1245G), XRCC1 rs1799782 (Arg194Trp; C26304T) and XRCC1 rs25487 (Arg399Gln; G28152A) polymorphisms on the modulation of pesticide-induced DNA damage in a total of 450 subjects (225 pesticide-exposed agricultural workers and 225 age- and sex-matched controls). DNA damage was estimated by alkaline comet assay using silver-staining method. Genotyping was carried out by PCR-RFLP using site-specific restriction enzymes. Mann-Whitney U-test revealed elevation in DNA damage parameters (p < 0.01) in pesticide-exposed agricultural workers than controls. Chi-square test showed significant (p < 0.05) differences in the XRCC1 Arg194Trp (C26304T) and Arg399Gln (G28152A) genotypes among two groups. Multivariate logistic-regression analysis revealed that heterozygous genotypes of OGG1 rs1052133 (326Ser/Cys; 1245CA), XRCC1 rs1799782 (194Arg/Trp; 26304CT) and XRCC1 rs25487 (399Arg/Gln; 2815GA) were positively associated (p < 0.05) with elevated DNA damage parameters in pesticide-exposed agricultural workers. Our results strongly indicate significant positive association of variant OGG1 and XRCC1 genotypes with reduced DRC and higher pesticide-induced DNA damage in North-West Indian agricultural workers.