Exposure of Human Lung Cells to Tobacco Smoke Condensate Inhibits the Nucleotide Excision Repair Pathway

Abstract

Exposure to tobacco smoke is the number one risk factor for lung cancer. Although the DNA damaging properties of tobacco smoke have been well documented, relatively few studies have examined its effect on DNA repair pathways. This is especially true for the nucleotide excision repair (NER) pathway which recognizes and removes many structurally diverse DNA lesions, including those introduced by chemical carcinogens present in tobacco smoke. The aim of the present study was to investigate the effect of tobacco smoke on NER in human lung cells. We studied the effect of cigarette smoke condensate (CSC), a surrogate for tobacco smoke, on the NER pathway in two different human lung cell lines; IMR-90 lung fibroblasts and BEAS-2B bronchial epithelial cells. To measure NER, we employed a slot-blot assay to quantify the introduction and removal of UV light-induced 6–4 photoproducts and cyclobutane pyrimidine dimers. We find a dose-dependent inhibition of 6–4 photoproduct repair in both cell lines treated with CSC. Additionally, the impact of CSC on the abundance of various NER proteins and their respective RNAs was investigated. The abundance of XPC protein, which is required for functional NER, is significantly reduced by treatment with CSC while the abundance of XPA protein, also required for NER, is unaffected. Both XPC and XPA RNA levels are modestly reduced by CSC treatment. Finally, treatment of cells with MG-132 abrogates the reduction in the abundance of XPC protein produced by treatment with CSC, suggesting that CSC enhances proteasome-dependent turnover of the protein that is mediated by ubiquitination. Together, these findings indicate that tobacco smoke can inhibit the same DNA repair pathway that is also essential for the removal of some of the carcinogenic DNA damage introduced by smoke itself, increasing the DNA damage burden of cells exposed to tobacco smoke.

Xeroderma Pigmentosum Group C Deficiency Alters Cigarette Smoke DNA Damage Cell Fate and Accelerates Emphysema Development

“…Our findings suggest that chronic CS exposure itself may be sufficient to suppress DNA repair through decreased XPC expression, possibly through promoter hypermethylation, as has been previously described as modulating XPC expression (30). Decreased XPC expression was previously observed 24 hours after in vitro exposure to CS condensate due to proteasomal degradation (31). This suggests that XPC expression may be altered both early after CS exposure, by post-translational modification, as well as later through transcriptional regulation, leading to decreased DNA damage repair, causing increased pulmonary cell death, altered autophagic function, and development of emphysema.…”

Diet from Mantisa religiosa-egg case abolishes pulmonary dysfunctions triggered by sub-acute exposure to aerosolized-petroleum hydrocarbons in rat model

“…This supports the studies that extracellular nucleotides and nucleosides are essential signaling molecules in the lung for its stability and constancy [54,55]. Additionally, a composite linkage of surface ectonucleotidases regulates nucleotide and nucleoside levels in alveolar lining fluid [56] whereas adenosine mediates the lung workability via the production of energy [57]. Conversely, the reduction of AMP hydrolysis following treatments with 4% DSMFF suggests high conservation of ATP in the lung [58].…”

Waterpipe smoke condensate influences epithelial to mesenchymal transition and interferes with the cytotoxic immune response in non-small cell lung cancer cell lines

“…Indeed, we observed that WPSC treatment resulted in increased DNA damage and a subsequent increase in γH2AX and 53BP1, which is consistent with the recent finding of Yoshida et al , indicating that tobacco smoking resulted in the increase in mutational burden of lung cells ( 35 ), and with a known increase in the expression of both γH2Ax and 53BP1 in several cancers including breast, bladder, lung, head and neck ( 36 ). By contrast, cigarette smoke has been shown to induce a decrease in nucleotide excision repair mechanisms, and does induce DNA damage as measured by COMET assay ( 37 , 38 ), which raises the interesting possibility that other factors present in WPS may induce a toxic response independent of DNA damage in these cells.…”