Time-Dependent Regulation of Apoptosis by AEN and BAX in Response to 2-Aminoanthracene Dietary Consumption

BACKGROUND/OBJECTIVE: The modulation of the toxic effects of 2-aminoanthracene (2AA) on the liver by apoptosis was investigated. Fisher-344 (F344) rats were exposed to various concentrations of 2AA for 14 and 28 days. The arylamine 2AA is an aromatic hydrocarbon employed in manufacturing chemicals, dyes, inks, and it is also a curing agent in epoxy resins and polyurethanes. 2AA has been detected in tobacco smoke and cooked foods. METHODS: Analysis of total messenger ribonucleic acid (mRNA) extracts from liver for apoptosis-related gene expression changes in apoptosis enhancing nuclease (AEN), Bcl2-associated X protein (BAX), CASP3, Jun proto-oncogene (JUN), murine double minute-2 p53 binding protein homolog (MDM2), tumor protein p53 (p53), and GAPDH genes by quantitative real-time polymerase chain reaction (qRT-PCR) was coupled with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and caspase-3 (Casp3) activity assays. RESULTS: Specific apoptosis staining result does not seem to show significant difference between control and treated animals. This may be due to freeze-thaw artifacts observed in the liver samples. However, there appears to be a greater level of apoptosis in medium- and high-dose (MD and HD) 2AA treated animals. Analyses of apoptosis-related genes seem to show AEN and BAX as the main targets in the induction of apoptosis in response to 2AA exposure, though p53, MDM2, and JUN may play supporting roles. CONCLUSION: Dose-dependent increases in mRNA expression were observed in all genes except Casp3. BAX was very highly expressed in the HD rats belonging to the 2-week exposure group. This trend was not observed in the animals treated for 4 weeks. Instead, AEN was rather very highly expressed in the liver of the MD animals that were treated with 2AA for 28 days.