Metabolites of Tobacco- and E-Cigarette-Related Nitrosamines Can Drive Cu²⁺-Mediated DNA Oxidation

Abstract

Nitrosamine metabolites resulting from cigarette smoking and E-cigarette (E-cig) vaping cause DNA damage that can lead to genotoxicity. While DNA adducts of metabolites of nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N-nitrosonornicotine (NNN) are well-known tobacco-related cancer biomarkers, only a few studies implicate NNN and NNK in DNA oxidation in humans. NNK and NNN were found in the urine of E-cigarette users who never smoked cigarettes. This paper proposes the first chemical pathways of DNA oxidation driven by NNK and NNN metabolites in redox reactions with Cu 2+ and NADPH leading to reactive oxygen species (ROS). A microfluidic array with thin films of DNA and metabolic enzymes that make metabolites of NNN and NNK in the presence of Cu 2+ and NADPH was used to estimate relative rates of DNA oxidation. Detection by electrochemiluminescence (ECL) employed a new ECL dye [Os(tpy-benz-COOH) 2 ] 2+ that is selective for and sensitive to the primary DNA oxidation product 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxodG) in DNA. Enzyme−DNA films on magnetic beads were used to produce nitrosamine metabolites that enter ROS-forming redox cycles with Cu 2+ and NADPH, and liquid chromatography−mass spectrometry (LC−MS) was used to quantify 8-oxodG and identify metabolites. ROS were detected by optical sensors. Metabolites of NNK and NNN + Cu 2+ + NADPH generated relatively high rates of DNA oxidation. Lung is the exposure route in smoking and vaping, human lung tissue contains Cu 2+ and NADPH, and lung microsomal enzymes gave the highest rates of DNA oxidation in this study. Also, E-cigarette vapor contains 6-fold more copper than that in cigarette smoke, which could exacerbate DNA oxidation.

Os(II)-Bridged Polyarginine Conjugates: The Additive Effects of Peptides in Promoting or Preventing Permeation in Cells and Multicellular Tumor Spheroids

“…We reported recently on the preparation and photophysical characteristics of the achiral Os­(II) parent complex, [Os­(tpybenzCOOH) 2 ] 2+ , used in this study. , For an osmium polypyridyl complex, it exhibits a comparatively high emission quantum yield and in particular, as described, has the advantage from the perspective of the current application of a linear structure with bilateral conjugation sites, offering the possibility to extend a linear peptide sequence bridged by the metal center. The tridentate ligand structure also avoids the complexity of the possibility of preparation of isomers.…”

Electrochemical transformations catalyzed by cytochrome P450s and peroxidases

“…Results showed that metabolites of NNK and NNN + Cu 2+ + NADPH generated high rates of DNA oxidation by forming reactive oxygen species (ROS) in a complex pathway as the ultimate oxidants. 296 In biological catalysis, multiple enzymes can mediate multistep conversions. Clopidogrel as a thienopyridine antiplatelet agent is used for treatment of cardiovascular diseases.…”

“…The metabolites of nitrosamines from cigarette smoke can lead to DNA oxidation and genotoxicity. 296 Metabolites of nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N -nitrosonornicotine (NNN) were formed by bioelectrocatalysis in a 3d-printed microfluidic array loaded with thin films of DNA, CYPs and other enzymes that make metabolites in presence of Cu 2+ and NADPH to obtain relative rates of DNA oxidation. Here, electrochemiluminescence (ECL) measurements employing a soluble ECL dye, [Os(tpy-benz-COOH) 2 ] 2+ were carried out to detect the primary DNA oxidation product 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxodG, Fig.…”

Metal Peptide Conjugates in Cell and Tissue Imaging and Biosensing

“…Recent studies have highlighted the potential of Os(II) polypyridyl complexes for detection of oxidative damage and intracellular reactive oxygen species [ 10 , 261 , 262 ]. The absence of oxygen sensitivity in the case of Os(II) complexes but potential redox sensitivity offers an advantage in their application as intracellular sensors over complexes of ruthenium or iridium.…”