Cell Biology

Methods for Studying the Mechanisms of Action

Studies at cellular and molecular levels complement epidemiological and animal experimental studies for evaluating the risks presented by hazardous substances at the workplace. Defined cell systems, such as cell cultures, can be used to study the mechanisms of action of hazardous substances in a standardized, reproducible and quality-assured manner.

Cell culture systems suitable for addressing the problems, which are often study-specific, are identified and characterized at the IPA with regard to their growth behaviour and whether they possess xenobiotic-metabolizing enzymes. At present, suitable cell lines are being used to study the cellular processes of hazardous substances that cause lung cancer or bladder cancer.

The dose-dependent and time-dependent effects of lung and bladder carcinogens such as polycyclic aromatic hydrocarbons (PAHs) and aromatic amines are typically tested at a molecular level. Early and possibly reversible changes (such as the induction of xenobiotic-metabolizing enzymes) and irreversible effects (e.g. apoptosis, necrosis) are recorded in order to obtain the most comprehensive picture possible of the effect of these hazardous substances.

Extremely sensitive protein chemistry methods (such as western blot and luminescence assays) and cytogenetic methods (comet assay, micronucleus test) are also used. Specifically for PAHs, a chemical analytical method for the detection of DNA adducts of benzo[a] pyrene is available that provides insights into the initial stages of carcinogenic action of PAHs.

By contrast, effects upon the cell cycle and cell proliferation are studied by biological analytical methods, including flow cytometry, which in turn provides insights into the progression and growth of the cells treated with a hazardous substance. Cytotoxic effects, i.e. hazardous substance concentrations that lead to cell death, are also studied. The full picture of observed effects and mechanisms permits an estimation of the concentration above which adverse effects may be anticipated, and an indication of what strategies may be needed at the cellular level to prevent these effects.