Genetic Toxicology

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Description

Project manager: Björn Hellman

In our research we focus on primary DNA damage in the form of DNA strand breaks using the Comet assay. With this method, single and double strand breaks are captured in single cells. We have further developed the original protocol for the alkaline version of the assay by streamlining laboratory, analysis and data processing processes. Method development has so far resulted in articles describing a protocol for what we call Flash-comet (Bivehed et al., 2020) and we have also launched an alternative statistical method (UCDAS) for the analysis of comet data (Bivehed et al., 2020). As part of this methodological work, we have also shown both at the DNA molecule level, gene level and genome level, that the integrity of DNA is affected by a number of different factors which are often overlooked in traditional Comet assay protocols (Bivehed et al., 2023). In collaboration with Professor Ola Söderberg's research group, we have also developed a method (Comet-PADDA) that makes it possible to distinguish between single and double strand breaks in one and the same "comet tail" (Bivehed et al. 2024). The thesis defended by Erik Bivehed in 2024 was named by the Swedish Association for Toxicology as the best thesis in the subject of toxicology that year.

The ultimate goal for us is to improve the risk assessment regarding human exposure to genotoxic agents. When exposed to carcinogenic substances, it is important to distinguish between genotoxic carcinogens and substances that increase the risk of cancer by acting via other mechanisms. DNA damage can, for example, occur when a substance directly attacks DNA, but it can also occur as a result of, for example, cytotoxicity – which for a genetic toxicologist is of less importance when it comes to the potential carcinogenicity of a compound. Nowadays we mainly work with cultured cells to identify genotoxic substances and in method development, but in our previous studies we have used primary DNA damage in peripheral lymphocytes as biological exposure markers (e.g. in blood samples from patients who have received chemotherapy or from those exposed to radon in the home environment). In other projects, we established long-term cultures of lymphocytes from blood donors to, among other things, study individual variation in sensitivity to genotoxic agents, DNA repair, oxidative DNA damage, etc.

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  • Vaghef , Hellman B. (1995). Demonstration of chlorobenzene-induced DNA damage in mouse lymphocytes using the single cell gel electrophoresis assay. Toxicology; 96, 19-28.
  • Vaghef, H., Nygren P., Edling, C., Bergh J., Hellman B. (1997). Alkaline single cell gel electrophoresis and human biomonitoring for genotoxicity: a pilot study on breast cancer patients undergoing chemotherapy including cyclophosphamide, Mutat Res.; 395, 127-138.
  • Andersson M, Agurell E., Vaghef, H., Bolcsfoldi G., Hellman B. (2003). Extended-term cultures of human T-lymphocytes and the comet assay: a useful combination when testing for genotoxicity in vitro? Res.; 540, 43-55.
  • Andersson M.A., Peterson-Grawé K.W., Karlsson, O.M., Abramsson-Zetterberg L.A.G., Hellman B.E. (2007). Evaluation of the potential genotoxicity of chromium picolinate in mammalian cells in vivo and in vitro. Food & Chemical Toxicol.; 45, 1097-1106.
  • Demma J., Hallberg K., Hellman B. (2009). Genotoxicity of plumbagin and its effects on catechol and NQNO-induced DNA damage in mouse lymphoma cells. In Vitro;23, 266-271.
  • Åsgård, R. Hagdoost S., Osterman Golkar S., Hellman, Czene S. (2013). Evidence for different mechanisms of action behind the mutagenic effects of 4-NOPD and OPD: the role of DNA damage, oxidative stress and an imbalanced nucleotide pool. Mutagenesis; 28, 637-644.
  • Bivehed, E. Gustafsson A., Berglund A., Hellman B. (2020). Evaluation of potential DNA damaging effects of nitenpyram and imidacloprid in human U937-cells using a new statistical approach to analyse comet data. Exposure and Health; 12, 547-554. DOI: 10.1007/s12403-019-00328-6.
  • Bivehed, E. Söderberg O., Hellman B.(2020). Flash-comet: Significantly improved speed and sensitivity of the comet assay through the introduction of lithium-based solutions and a more gentle lysis. Mutat. Res.;(2020). Doi: 10.1016/j.mrgentox.2020.503240.
  • Bivehed E., Hellman B., Fan Y., Haglöf J., Buratovic S. (2023) DNA integrity under alkaline conditions: An investigation of factors affecting the comet assay, Mutat. Res.; Doi: 10.1016/j.mrgentox.2023.503680.
  • Bivehed, Hellman B., Wenson L., Stenerlöw B., Söderberg O., Heldin J. (2024) Visualizing DNA single and double-strand breaks in the Flash comet assay by DNA polymerase-assisted end-labelling. Nucleic Acid Res.; Doi: 10.1093/nar/gkae009.

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