Effect of frying-meat emission particulate on 17β-estradiol 2- and 4-hydroxylation in human lung adenocarcinoma CL5 cells

The effect of airborne frying-meat emission particulate (FMEP) on metabolism of 17β-estradiol (E₂) to potentially toxic catechol estrogens 2- and 4-hydroxyestradiol (2- and 4-OH-E₂) was determined using human lung adenocarcinoma CL5 cells treated with organic extracts of beef FMEP. E₂ was incubated with microsomes prepared from untreated CL5 cells or cells treated with 200 μg/ml FMEP extract for 6 h. E₂ metabolites formed were analyzed by high-performance liquid chromatography (HPLC). The results revealed that treatment with FMEP produced three-and twofold increases of 2- and 4-hydroxylation of E₂, respectively. Monooxygenase activity and immunoblot analyses showed that FMEP markedly induced microsomal 7-ethoxyresorufin O-deethylase (EROD) activity and cytochrome P-450 (CYP) IAI and CYPIBI protein levels. Similar increases in E₂ hydroxylation, EROD activity, and CYP protein levels were observed with HepG2 human hepatoma and MCF-7 human breast cancer cells treated with FMEP or 1 μM dibenz[a,h]anthracene. Cotreatment of CL5 cells with FMEP extract and 2 μM α-naphthoflavone, an arylhydrocarbon receptor antagonist, blocked the inductive effects of FMEP on E₂ hydroxylation and EROD activity. Additions of 0.01, 0.1, or 1 μM α-naphthoflavone, a CYP inhibitor, to microsomes produced concentration-dependent decreases in E₂ 2-hydroxylation and EROD activity of CL5 cells induced by dibenz[a,h]anthracene. The present finding demonstrates that FMEP can increase formation of 2-OH-E₂ and 4-OH-E₂ by human lung cells, and induction of CYP1A1 and CYP1B1 is a potential mechanism underlying increased E₂ metabolism. The toxicological significance of FMEP and estrogen interaction warrants further investigation.