Research Article

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†‡

  1. Channa Keshava1,2,§,
  2. Rao L. Divi3,§,
  3. Tracey L. Einem3,
  4. Diana L. Richardson1,
  5. Sarah L. Leonard3,
  6. Nagalakshmi Keshava2,
  7. Miriam C. Poirier3,*,
  8. Ainsley Weston1,4

Article first published online: 16 JAN 2009

DOI: 10.1002/em.20449

Issue

Environmental and Molecular Mutagenesis

Environmental and Molecular Mutagenesis

Volume 50, Issue 2, pages 134–144, March 2009

Additional Information

How to Cite

Keshava, C., Divi, R. L., Einem, T. L., Richardson, D. L., Leonard, S. L., Keshava, N., Poirier, M. C. and Weston, A. (2009), 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. Environ. Mol. Mutagen., 50: 134–144. doi: 10.1002/em.20449

Author Information

  1. 1

    Molecular Carcinogenesis Team, Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia

  2. 2

    National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave, NW, Washington, D.C

  3. 3

    Carcinogen-DNA Interactions Section, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland

  4. 4

    Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia

  1. §

    The first two authors contributed equally to this work.

*Carcinogen-DNA Interactions Section, National Cancer Institute, Bldg. 37, Rm. 4032, NIH, 37 Convent Dr., MSC-4255, Bethesda, MD 20892-4255, USA

  1. †

    This article is a US Government work and, as such, is in the public domain in the United States of America.

  2. ‡

    The mention of commercial products in this article does not constitute an endorsement by NIOSH, NCI, or the US Environmental Protection Agency (EPA). The findings and conclusions in this article are those of the authors and do not necessarily represent the views or policies of NIOSH, NCI or the EPA.

Publication History

  1. Issue published online: 2 FEB 2009
  2. Article first published online: 16 JAN 2009
  3. Manuscript Accepted: 14 OCT 2008
  4. Manuscript Received: 17 APR 2008

Funded by

  • Intramural Research Programs of the US Centers for Disease Control (CDC)
  • National Institute for Occupational Safety and Health (NIOSH)
  • US National Institutes of Health (NIH) National Cancer Institute (NCI) Center for Cancer Research

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Keywords:

  • polycyclic aromatic hydrocarbons;
  • microarray;
  • chemoprevention;
  • chlorophyllin;
  • NQO1;
  • chemiluminescence immunoassay;
  • interferon

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 μM BP for 24 hr in the presence or absence of 5 μM 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 up-regulation 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. Environ. Mol. Mutagen. 2009. Published 2009 Wiley-Liss, Inc.

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