Combined genotoxic effects of a polycyclic aromatic hydrocarbon (B(a)P) and an heterocyclic amine (PhIP) in relation to colorectal carcinogenesis

PLoS One. 2013;8(3):e58591. doi: 10.1371/journal.pone.0058591. Epub 2013 Mar 6.

Abstract

Colorectal neoplasia is the third most common cancer worldwide. Environmental factors such as diet are known to be involved in the etiology of this cancer. Several epidemiological studies have suggested that specific neo-formed mutagenic compounds related to meat consumption are an underlying factor involved in the association between diet and colorectal cancer. Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) are known mutagens and possible human carcinogens formed at the same time in meat during cooking processes. We studied the genotoxicity of the model PAH benzo(a)pyrene (B(a)P) and HCA 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), alone or in mixture, using the mouse intestinal cell line Apc(Min/+), mimicking the early step of colorectal carcinogenesis, and control Apc(+/+) cells. The genotoxicity of B(a)P and PhIP was investigated using both cell lines, through the quantification of B(a)P and PhIP derived DNA adducts, as well as the use of a genotoxic assay based on histone H2AX phosphorylation quantification. Our results demonstrate that heterozygous Apc mutated cells are more effective to metabolize B(a)P. We also established in different experiments that PhIP and B(a)P were more genotoxic on Apc (Min/+) cells compared to Apc (+/+) . Moreover when tested in mixture, we observed a combined genotoxicity of B(a)P and PhIP on the two cell lines, with an increase of PhIP derived DNA adducts in the presence of B(a)P. Because of their genotoxic effects observed on heterozygous Apc mutated cells and their possible combined genotoxic effects, both B(a)P and PhIP, taken together, could be implicated in the observed association between meat consumption and colorectal cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Benzo(a)pyrene / toxicity*
  • Cell Line
  • Chromatography, High Pressure Liquid
  • Colorectal Neoplasms / chemically induced*
  • DNA Adducts / drug effects
  • Histones / drug effects
  • Histones / metabolism
  • Humans
  • Imidazoles / toxicity*
  • Intestinal Mucosa / cytology
  • Meat / adverse effects*
  • Meat / analysis
  • Mice
  • Mutagenicity Tests
  • Phosphorylation / drug effects
  • Tandem Mass Spectrometry

Substances

  • DNA Adducts
  • Histones
  • Imidazoles
  • Benzo(a)pyrene
  • 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine

Grant support

This research was funded in part by the NeoMeaTox Inca program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding was received for this study.