Cigarette sidestream smoke delays nucleotide excision repair: inhibited accumulation of repair proteins at DNA lesions

Abstract

Cigarette sidestream smoke (CSS) contains many carcinogens that induce DNA damage. DNA damage plays an important role in the initiation of cancer and several diseases, and repair is the major defense mechanism; however, the relationship between CSS and the repair of DNA damage remains unclear. We herein investigated whether CSS influences nucleotide excision repair (NER) in vivo and in vitro. HR-1 hairless mouse skin treated with CSS was exposed to UVB, as a result of which pyrimidine dimers (cyclobutane pyrimidine dimers (CPDs) and pyrimidine(6-4)pyrimidone photoproducts (6-4PPs)) were formed and repaired via the NER pathway. The immunohistochemical staining of CPDs revealed that their repair was delayed by the CSS treatment. This delay in NER and the underlying mechanisms were examined in the human skin cell lines, HaCaT and HSC-1. Dot-blot assays, enzyme-linked immunosorbent assay and local ultraviolet irradiation assays demonstrated that CSS delayed the repair of CPDs and 6-4PPs. The recruitment of the repair molecules, TFIIH, XPA and XPG to pyrimidine dimers was markedly inhibited by CSS. Semicarbazide, which reacts with aldehydes, recovered the CSS-induced inhibition of NER, and formaldehyde exerted similar inhibitory effects to those of CSS. These results suggest that aldehydes in CSS interfere with the recruitment of NER molecules to damaged sites, leading to a delay in the repair of pyrimidine dimers.

α,β-Unsaturated Aldehyde-Induced Delays in Nucleotide Excision Repair and the Contribution of Reactive Oxygen Species

“…Formaldehyde has been reported to delay the repair of UV-induced DNA damage. 16,18 We attributed unsaturated aldehyde-enhanced cell death to the impaired repair of UV-induced DNA damage. The formation and repair of 6-4PPs following a co-exposure to saturated/unsaturated aldehydes and UVB were assessed by ELISA (Figure 2A and B).…”

“…Cells were treated with aldehydes for 2 h. The concentrations of aldehydes were determined by reference to the concentration of formaldehyde in CSS. 16 The culture medium was changed to PBS including calcium and magnesium before UVB (main emission wavelength, 312 nm, Atto Co. Ltd., Tokyo, Japan) and UVC (main emission wavelength, 254 nm, Atto Co. Ltd., Tokyo, Japan) irradiation. The dose rates of UVB and UVC irradiation were 0.06 J/ cm 2 /min and 0.012 J/cm 2 /min, respectively.…”

“…We recently demonstrated that NER was inhibited by cigarette sidestream smoke (CSS) exposure . This was due to the impaired recruitment of NER proteins to DNA damage sites and mediated by aldehydes in CSS.…”

“…15 We recently demonstrated that NER was inhibited by cigarette sidestream smoke (CSS) exposure. 16 This was due to the impaired recruitment of NER proteins to DNA damage sites and mediated by aldehydes in CSS. Acrolein has been reported to inhibit BER and mismatch repair, in which the mRNA levels of repair molecules are similar, whereas protein degradation was enhanced.…”

Environmental exposures associated with elevated risk for autism spectrum disorder may augment the burden of deleterious de novo mutations among probands

“…Activation of the DDR pathways hinges on the capacity of the cell to detect aberrations in the genetic code, hence interference in the expression of these may cause delay or complete arrest in the damage-directed repair response. Although less frequently observed, genes encoding products required to effectively excise detected aberrations also demonstrate dysregulation following exposure to disorder-associated environmental agents, specifically within the NER response to induced DNA adducts (e.g., XPG ) [ 72 ]. In such instances, acquired mutations remain unextruded despite appropriate activation of the DDR, precluding the repair response and permitting DNA damage and, thereby, de novo variation to persist.…”