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Chlorophyllin significantly reduces benzo[a]pyrene-DNA adduct formation and alters cytochrome P450 1A1 and 1B1 expression and EROD activity in normal human mammary epithelial cells.

Authors
Keshava-C; Divi-RL; Einem-TL; Richardson-DL; Leonard-SL; Keshova-N; Poirier-MC; Weston-A
Source
Environ Mol Mutagen 2009 Mar; 50(2):134-144
NIOSHTIC No.
20035083
Abstract
We hypothesized that chlorophyllin (CHLN) would reduce benzo[a]pyrene-DNA (BP-DNA) adduct levels. Using normal human mammary epithelial cells (NHMECs) exposed to 4 mu M BP for 24 hr in the presence or absence of 5 mu M CHLN, we measured BP-DNA adducts by chemiluminescence immunoassay (CIA). The protocol included the following experimental groups: BP alone, BP given simultaneously with CHLN (BP+CHLN) for 24 hr, CHLN given for 24 hr followed by BP for 24 hr (preCHLN, postBP), and CHLN given for 48 hr with BP added for the last 24 hr (preCHLN, postBP+CHLN). Incubation with CHLN decreased BPdG levels in all groups, with 87% inhibition in the preCHLN, postBP+CHLN group. To examine metabolic mechanisms, we monitored expression by Affymetrix microarray (U133A), and found BP-induced up-regulation of CYP1A1 and CYP1B1 expression, as well as upregulation of groups of interferon-inducible, inflammation and signal transduction genes. Incubation of cells with CHLN and BP in any combination decreased expression of many of these genes. Using reverse transcription real time PCR (RT-PCR) the maximal inhibition of BP-induced gene expression, >85% for CYP1A1 and >70% for CYP1B1, was observed in the preCHLN, postBP + CHLN group. To explore the relationship between transcription and enzyme activity, the ethoxyresorufin-O-deethylase (EROD) assay was used to measure the combined CYP1A1 and CYP1B1 activities. BP exposure caused the EROD levels to double, when compared with the unexposed controls, The CHLN-exposed groups all showed EROD levels similar to the unexposed controls. Therefore, the addition of CHLN to BP-exposed cells reduced BPdG formation and CYP1A1 and CYP1B1 expression, but EROD activity was not significantly reduced.
Keywords
Cell-differentiation; Cell-metabolism; Cellular-reactions; DNA-adducts; Chemical-analysis; Chemical-composition; Chemical-indicators; Chemical-reactions; Chemical-synthesis; Immunochemistry; Metabolic-activation; Genes; Genetic-factors; Author Keywords: Polycyclic aromatic hydrocarbons; Microarray; Chemoprevention; Chlorophyllin; NQO1; Chemiluminescence immunoassay; Interfero
Contact
Miriam C. Poirier, Carcinogen-DNA Interactions Section, National Cancer Institute, Bldg. 37, Rm. 4032, NIH, 37 Convent Dr., MSC-4255, Bethesda, MD 20892-4255
CODEN
EMMUEG
Publication Date
20090301
Document Type
Journal Article
Email Address
poirierm@exchange.nih.gov
Funding Type
Grant
Fiscal Year
2009
NTIS Accession No.
NTIS Price
Issue of Publication
2
ISSN
0893-6692
NIOSH Division
DRDS; HELD
Source Name
Environmental and Molecular Mutagenesis. Environmental Mutagen Society 39th Annual Meeting Abstracts
State
WV; MD; DC
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