Gene expression and DNA adduct formation is modulated by chlorophyllin in normal human mammary epithelial cells exposed to benzo(a)pyrene (BP).
John-K; Divi-R; Keshava-C; Orozco-CC; Whipkey-DL; Poirier-MC; Nath-J; Weston-A
Mutat Res 2005 Sep; 577(Suppl 1):e170
Normal human mammary epithelial cell (NHMEC) strains were developed from breast tissue discarded at reduction mammoplasty and obtained through the Cooperative Human Tissue Network (CHTN is sponsored by the National Cancer Institute and the National Disease Research Interchange). These cell strains were used to monitor changes in gene expression and DNA adduct formation upon exposure to the pro-carcinogen BP in the presence or absence of chlorophyllin, a water soluble metalloporphyrin. Following treatment of NHMEC strains (n=7) with BP (4 M) in the presence or absence of chlorophyllin (5 M), genome-wide -3fold changes in gene expression were monitored over 24h by DNA-microarrays. The expression of CYP1A1 and CYP1B1 was monitored using real-time polymerase chain reaction (RT-PCR) in 15 NHMEC strains. Anti-benzo(a)pyrene-diol epoxide (BPDE)DNA antiserum was used by immunoassay to measure BP-DNA adducts in 10 strains. Among 7 NHMEC strains monitored using DNA-microarrays, up to 54 genes were induced upon treatment with BP alone, while 11 genes were downregulated. Chlorophyllin pre-treatment followed by co-treatment with BP and chlorophyllin of the above 7 NHMEC strains caused up-regulation of the expression of 129 genes and downregulation of 35 genes. Subsequently, wide inter-individual variation was observed in 15 strains for the induction of both CYP1A1 (3 to 96-fold) and CYP1B1 (2 to 43-fold) upon exposure to BP alone, and for their modulation by chlorophyllin (2 to 54-fold and 1 to 39-fold, respectively) when measured by RT-PCR. A reduction in BPDE-DNA adduct levels (48% to 86%) was observed in cells exposed to chlorophyllin following treatment with BP plus chlorophyllin. These results demonstrate inter-individual variation in the bioactivation of BP and the potential of chlorophyllin for reducing the formation of BP-DNA lesions. The data suggest that chlorophyllin may act as a chemopreventive agent for PAH-induced cancers in human populations.
Genes; DNA-adducts; Polycyclic-aromatic-hydrocarbons; Environmental-pollution; Pollution; Pollutants; DNA-damage; Cancer; Exposure-levels; Exposure-assessment
Conference/Symposia Proceedings; Abstract