Altered gene expression patterns in MCF-7 cells induced by the diesel particulate complex mixture SRM 1650 monitored using DNA microarrays.
Mahadevan-B; Keshava-C; Musafia-T; Pecaj-A; Weston-A; Baird-WM
Proceedings of the American Association for Cancer Research (AACR) 94th Annual Meeting, July 11-14, 2003, Washington, DC. 2nd edition. Philadelphia, PA: American Association for Cancer Research, 2003 Jul; 44:1052
Human exposures to polycyclic aromatic hydrocarbons (PAHs) occur in complex mixtures. Standard Reference Material (SRM) 1650-diesel particulate matter, characterized by the National Institute of Standards and Technology, is a mixture of PAHs and nitro-substituted PAHs. In this study, gene expression patterns were investigated in MCF-7 cells exposed for 24h to SRM 1650 alone or SRM 1650 plus either benzo[a]pyrene (BP) or dibenzo[a,l]pyrene (DBP). Gene expression was monitored using high density oligonucleotide arrays (Affymetrix U 133A) representing more than 22,000 human genes and expressed sequence tags. Duplicate treatments displayed a high degree of reproducibility. Gene expression was analyzed using Affymetrix GeneChip software. Global analyses of the gene expression data revealed alterations of at least 2 fold change [signal log ratio (SLR) less than or equal to -1 or greater than or equal to 1] in 156 RNA transcripts in response to SRM 1650 exposure. Increase in expression of cytochrome P450 (CYP) genes was observed in response to BP exposure (CYP1A1 and CYP1B1 ; SLR of 6.5 and 2.8, respectively). An additive induction of CYP1A1 and CYP1B1 was observed with cotreatment of SRM 1650 and BP. In contrast, no change in expression of CYP1A 1 and CYP1 B1 was observed when the cells were exposed to DBP. To study the effect of complex PAH mixtures on the metabolic activation of carcinogenic PAH to DNA-binding derivatives and to correlate Ěthe results with gene expression studies, PAH-DNA adduct formation was determined in MCF-7 cells. 33P-postlabeling and reversed-phase high-performance liquid chromatography (HPLC) analysis of samples revealed that SRM 1650 decreased the total level of BP-DNA adducts in comparison with BP alone. No significant difference in adducts was observed in response to either DBP alone or in 'combination with SRM 1650. These results not only provide a transcriptional signature for chemical carcinogen exposure but also suggest a major factor in carcinogenic activity of PAH within complex mixtures is the ability of the complex mixture to promote or inhibit the activation of carcinogenic PAH by the induction of CYP metabolic enzymes.
Cancer; Carcinogenesis; Exposure-levels; Polycyclic-aromatic-hydrocarbons; Polycyclic-hydrocarbons; Particulates; Diesel-emissions; Diesel-exhausts; Genetics
Abstract; Conference/Symposia Proceedings
Proceedings of the American Association for Cancer Research (AACR) 94th Annual Meeting, July 11-14, 2003, Washington, DC. 2nd edition