CYP1A1 and CYP1B1 gene expression and DNA adduct formation in normal human mammary epithelial cells exposed to benzo[a]pyrene in the absence or presence of chlorophyllin.
Benzo[a]pyrene (BP) is a potent pro-carcinogen and ubiquitous environmental pollutant. Here, we examined the induction and modulation of CYP1A1 and CYP1B1 and 10-(deoxyguanosin-N(2)-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPdG) adduct formation in DNA from 20 primary normal human mammary epithelial cell (NHMEC) strains exposed to BP (4muM) in the absence or presence of chlorophyllin (5muM). Real-time polymerase chain reaction (RT-PCR) analysis revealed strong induction of both CYP1A1 and CYP1B1 by BP, with high levels of inter-individual variability. Variable BPdG formation was found in all strains by r7, t8-dihydroxy-t-9, 10 epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE)-DNA chemiluminescence assay (CIA). Chlorophyllin mitigated BP-induced CYP1A1 and CYP1B1 gene expression in all 20 strains when administered with BP. Chlorophyllin, administered prior to BP-exposure, mitigated CYP1A1 expression in 18/20 NHMEC strains (p<0.005) and CYP1B1 expression in 17/20 NHMEC strains (p<0.005). Maximum percent reductions of CYP1A1 and CYP1B1 gene expression and BPdG adduct formation were observed when cells were pre-dosed with chlorophyllin followed by administration of the carcinogen with chlorophyllin (p<0.005 for CYP1A1 and CYP1B1 expression and p<0.0005 for BPdG adducts). Therefore, chlorophyllin is likely to be a good chemoprotective agent for a large proportion of the human population.
John
Kaarthik
K
Genetics and Developmental Biology Program, West Virginia University, Morgantown, WV, United States.
Divi
Rao L
RL
Keshava
Channa
C
Orozco
Christine C
CC
Schockley
Marie E
ME
Richardson
Diana L
DL
Poirier
Miriam C
MC
Nath
Joginder
J
Weston
Ainsley
A
D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D001564:Benzo(a)pyrene / Q000494:pharmacology*; D002735:Chlorophyllides / Q000494:pharmacology*; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics*; D065633:Cytochrome P-450 CYP1B1; D018736:DNA Adducts; D006801:Humans; D042361:Mammary Glands, Human / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002735:Chlorophyllides; D018736:DNA Adducts; D001564:Benzo(a)pyrene; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D019363:Cytochrome P-450 CYP1A1; D065633:Cytochrome P-450 CYP1B1; C007020:chlorophyllin