Quantification of DNA and Protein Adducts of 1-Nitropyrene: Significantly Higher Levels of Protein than DNA Adducts in the Internal Organs of 1-Nitropyrene Exposed Rats

Abstract

1-Nitropyrene (1NP) level is closely associated with the mutagenicity of diesel exhaust and is being used as the marker molecule for diesel exhaust. Thus, quantitation of the exposure to 1NP may provide an efficient method for biomonitoring human exposure to diesel exhaust and risk assessment. Using ultra-performance liquid chromatography coupled with fluorescence or tandem mass spectrometric detection methods, we quantitated and compared in this study the DNA and protein adducts of 1NP in internal organs of 1NP-exposed rats. While previous studies using radioactivity-based detection methods were descriptive in nature and focused on the mutation-associated genetic materials, the results of our quantitative analysis showed, for the first time, a significantly higher concentration of the protein adduct than the DNA adduct in the tissue samples. The data also revealed higher in vivo stability of the protein adduct than that of the DNA adduct. Our results provide solid evidence that demonstrates that the protein adduct might be a more-sensitive dosimeter for 1-NP and, thus, diesel-exhaust exposure.

Quantitation of Protein Adducts of Aristolochic Acid I by Liquid Chromatography–Tandem Mass Spectrometry: A Novel Method for Biomonitoring Aristolochic Acid Exposure

“…Kidney and liver proteins of AAI-exposed rats were isolated by ammonium sulfate precipitation after slices of kidney and liver tissues were homogenized using a high-speed tissue-tearor homogenizer, as described previously. , The whole blood was allowed to sit undisturbed at room temperature for 30 min, followed by centrifugation (4000 g , 10 min, 4 °C) to remove blood clots. Saturated ammonium sulfate solution was added dropwise to the rat serum until ∼60% saturation, agitated gently at room temperature for 30 min, and centrifuged (18 000 g , 10 min) to precipitate out the globulins. , The supernatant, the albumin solution, was desalted, washed, and concentrated by centrifugation (4500 g , 10 min) in a Nanosep 10K centrifugal device.…”

“…Second, unlike DNA lesions, − protein adducts are not repaired by repair enzymes and could accumulate during the lifespan of the proteins; therefore, a higher abundance of protein adducts could be accumulated for analysis. Currently, protein adducts are used to biomonitor the exposure to a variety of carcinogens including aromatic amines, aflatoxin, sulfur mustards, among others. − Lastly, Sidorenko recently demonstrated the in vitro and in vivo formation of protein adducts of aristolochic acid I (AAI) by coupling polyacrylamide gel with chemiluminescence detection . However, the chemical structures of the adducts are yet to be characterized, which hampered their detection and quantitation by developing a liquid chromatography–tandem mass spectrometric (LC–MS/MS) method of higher selectivity.…”

Profiling How the Gut Microbiome Modulates Host Xenobiotic Metabolism in Response to Benzo[a]pyrene and 1-Nitropyrene Exposure

“…13−15 Another example is the metabolism of nitrated PAHs, which results in the formation of protein adducts that accumulate at higher levels than DNA adducts and have higher stability. 16 Therefore, liver metabolism must be tightly regulated to avoid these potentially harmful side processes, and understanding the inputs that lead these processes awry is crucial.…”

“…PAH exposure occurs from inhaling smoke and diesel exhaust, drinking from contaminated water sources, as well as ingesting grilled food. − PAHs can be cleared from the human body through phase 1 and 2 metabolism, but these otherwise helpful metabolic processes can sometimes result in the bioactivation of intermediates that are more harmful than the parent toxin . One example is the conversion of benzo­[ a ]­pyrene into electrophilic epoxides that result from cytochrome P450 (P450) oxidation, which can readily form DNA adducts and potentially lead to tumor formation. − Another example is the metabolism of nitrated PAHs, which results in the formation of protein adducts that accumulate at higher levels than DNA adducts and have higher stability . Therefore, liver metabolism must be tightly regulated to avoid these potentially harmful side processes, and understanding the inputs that lead these processes awry is crucial.…”