Induction of cytochrome P450 isozymes in human amnion FL cells

Abstract

The human epithelial FL cell line contains low levels of constitutive ethoxyresorufin O-deethylase, ethoxycoumarin O-deethylase and aminopyrine N-demethylase activities, of which ethoxyresorufin O-deethylase could be induced by norepinephrine, β-naphthoflavone and 3-methylcholanthrene, but ethoxycoumrine O-deethylase and aminopyrine N-demethylase activities could be induced by norepinephrine, β-naphthoflavone and 3-methylcholanthrene as well as phenobarbital. Inducibility of ethoxyresorufin O-deethylase, ethoxycoumarin O-deethylase and aminopyrine N-demethylase activities was 3.1–6.7-, 1.8–3.1- and 1.4–2.0-fold respectively. Co-treatment with 3-methylcholanthrene and norepinephrine resulted in higher ethoxyresorufin O-deethylase and aminopyrine N-demethylase activities than treatment with 3-methylcholanthrene alone. The induced ethoxyresorufin O-deethylase and ethoxycoumarin O-deethylase activities remained at a high level for 24–36 h after removal of the inducer from the medium. The metabolizing ability of induced FL cells is stronger than that of non-induced ones in a given time following induction. The results further confirm that it is feasible to use the cytochrome P450 isozyme-induced FL cell as a biological indicator in short-term tests for screening promutagens/procarcinogens.