Modulation of CYP1A1 and CYP1B1 expression by chlorophyllin in normal human mammary epithelial cells exposed to benzo(a)pyrene.
John-K; Keshava-C; Divi-RL; Whipkey-DL; Poirier-MC; Weston-A; Nath-J
Environ Mol Mutagen 2004 Jan; 44(3):208
Benzo(a)pyrene (BP) is a ubiquitous procarcinogen that induces various cytochrome P450s including steroid hydroxylases. In human tissues it may perturb hormonal metabolism or be converted to metabolites that damage DNA. Using normal human mammary epithelial cells, we previously showed inter-individual variation for induction of CYP1A1 and CYP1B1 enzymes by BP. To investigate mitigation of CYP1A1 and CYP1B1 induction, a panel of 10 primary normal human mammary epithelial cell strains was exposed to BP in the presence of chlorophyllin. Cell strains were derived from tissue discarded at reduction mammoplasty obtained through the Cooperative Human Tissue Network (National Cancer Institute and National Disease Research Interchange sponsored). Each cell strain was subjected to four separate 24h treatment protocols: BP (4 microgram M) alone, BP plus chlorophyllin (5 microgram M), chlorophyllin pretreatment (24h) followed by BP, and chlorophyllin pretreatment followed by BP plus chlorophyllin. Total RNA extracted from each treatment group was reverse transcribed, and the expression levels of CYP1A1 and CYP1B1 were monitored using real time polymerase chain reaction (RT-PCR). Maximum induction of both CYP1A1 (7 to 96-fold) and CYP1B1 (8 to 43-fold) was observed in the group treated with BP alone. Minimal induction of CYP1A1 (2 to 54-fold) and CYP1B1 (3 to 39-fold) was observed in the group pretreated with chlorophyllin followed by BP plus chlorophyllin. Further studies will examine the impact of chlorophyllin treatment on BP-DNA adduct formation in normal human mammary epithelial cells. These studies show substantial inter-individual variations in CYP1A1 and CYP1B1 induction subsequent to BP exposure, as well as inter-individual variation in response to the chemopreventive agent chlorophyllin.
Human-factors-engineering; Humans; Cell-alteration; Cell-biology; Cell-differentiation; Cell-metabolism; Cellular-reactions
CDC, Toxicol & Mol Biol Lab, NIOSH, Morgantown, WV 26505
Environmental and Molecular Mutagenesis