Cytochrome P450 1A1
CYP1A1 enzymatic activity was evaluated in cultured liver cells, and taken as a
biological indicator of the presence of inducers of this
isoform in urban
airborne particulate matter fraction samples. It is known that
CYP1A1 inducers can play an important role in the risk of mutagenesis and
carcinogenesis by environmental pollution. A romatic
polycyclic hydrocarbons PAH from urban air were collected in the city of Genoa Italy at two sites on two different days of the year. The objective of the study was to compare the inducibility of cultured rat hepatocytes with that of MH1C1 and FaO rat
hepatoma cell lines after exposure to a PAH mixture and to a standard compound, such as
benzo b fluoranthene B b F. Cytotoxic effects of the tested concentrations were evaluated by means of 3 4,5, dimenthylthyazol 2 yl 2,5 diphenyltetrazolium
bromide MTT and
lactate dehydrogenase release LDH tests, the potency of inducers by
ethoxyresorufin O deethylase EROD assay. The results were in agreement in the three cellular systems: after exposure to the PAH mixture, an induction at low concentrations was observed; whereas no induction, but rather a decrease in activity was shown at higher concentrations; instead, the exposure to pure B b F showed a dose-response relationship in all cells, even at the highest doses. Such a difference between the toxicity of the
complex mixture and that of the pure compound could be ascribed to the presence of
drug metabolism inhibitors in the mixture, or to interactions between the original components and their metabolites. The finding that the cell lines responded to the
CYP1A1 induction in a very efficient way gives further proof of the applicability of this system to environmental biomonitoring.