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

Abstract

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-N2-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 (4 μM) in the absence or presence of chlorophyllin (5 μM). 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.

Chemopreventive Potential of Chlorophyllin: A Review of the Mechanisms of Action and Molecular Targets

“…CHL treatment was found to downregulate the expression of interleukin 1 beta, a proinflammatory cytokine with a proangiogenic role in human mammary cell lines exposed to B[a]P (15). Studies from our laboratory have demonstrated that CHL administration inhibits tumor invasion and angiogenesis during DMBA-induced hamster buccal pouch carcinogenesis by upregulating tissue inhibitor of MMP-2 expression, and downregulating MMP-2, MMP-9, HIF-1a, VEGF, and VEGF receptor R2 (39,67).…”

“…Administration of CHL was also found to attenuate the formation of DNA adducts in normal human mammary epithelial cells exposed to B[a]P (15).…”

Chlorophylls and their Derivatives Used in Food Industry and Medicine

“…Both Chl and chlorophyllins (as well as Chlide a and b and pheophorbide a and b [273]) have been shown to inhibit the mutagenic and carcinogenic activities of several mutagens including polycyclic aromatic hydrocarbons, heterocyclic amins, and the mycotoxin, aflatoxin in several models both in vitro [204,216,[273][274][275][276][277][278][279][280] and in vivo [203,212,263,272,275,277,[281][282][283][284] (reviewed in [125,170,211,266,270,274]). Their antimutagenic activity is primarily based on preferential binding to these or other mutagens in the digestive tract, influencing their pharmacokinetics and decreasing their bioavailability, thus, reducing the possibility of DNA-adduct formation [203,212,264,[267][268][269]272,273,277,279,283,[285][286][287][288].…”

Influence of lifestyle choices on risks of CYP1B1 polymorphisms for prostate cancer

“…In prostate, mRNA transcripts including CYP1B1 were observed along with DNA adducts after incubating with 2‐amino‐1‐methyl‐6‐phenylimiazo[4,5‐b]pyridine (PhIP), 2‐amino‐3‐methylimidazo[4,5‐f]quinoline (IQ) and benzo[a]pyrene (B[a]P) 14. Also in primary mammary epithelial cells, B[a]P caused DNA adducts to form as well as CYP1B1 induction 15. Alternatively, PAHs or smoking can enhance levels of CYP1B1 expression 13, 16.…”

“…14,15 In prostate, mRNA transcripts including CYP1B1 were observed along with DNA adducts after incubating with 2-amino-1-methyl-6-phenylimiazo [4,5-b] induction. 15 Alternatively, PAHs or smoking can enhance levels of CYP1B1 expression. 13,16 As CYP1B1 is expressed in human prostate, 17 gene up-regulation and activation of pro-carcinogens may thus be influential in the prostatic carcinogenesis process.…”