Background: Chronic obstructive pulmonary disease (COPD) is characterised by oxidative stress and increased risk of lung carcinoma. Oxidative stress causes DNA damage which can be repaired by DNA-dependent protein kinase complex. Objectives: To investigate DNA damage/repair balance and DNA-dependent protein kinase complex in COPD lung and in an animal model of smoking-induced lung damage and to evaluate the effects of oxidative stress on Ku expression and function in human bronchial epithelial cells. Methods: Protein expression was quantified using immunohistochemistry and/or western blotting. DNA damage/repair was measured using colorimetric assays. Results: 8-OH-dG, a marker of oxidant-induced DNA damage, was statistically significantly increased in the peripheral lung of smokers (with and without COPD) compared with non-smokers, while the number of apurinic/apyrimidinic (AP) sites (DNA damage and repair) was increased in smokers compared with non-smokers (p=0.0012) and patients with COPD (p<0.0148). Nuclear expression of Ku86, but not of DNA-PKcs, phospho-DNA-PKcs, Ku70 or γ-H2AFX, was reduced in bronchiolar epithelial cells from patients with COPD compared with normal smokers and non-smokers (p<0.039). Loss of Ku86 expression was also observed in a smoking mouse model (p<0.012) and prevented by antioxidants. Oxidants reduced (p<0.0112) Ku86 expression in human bronchial epithelial cells and Ku86 knock down modified AP sites in response to oxidative stress. Conclusions: Ineffective DNA repair rather than strand breakage per se accounts for the reduced AP sites observed in COPD and this is correlated with a selective decrease of the expression of Ku86 in the bronchiolar epithelium. DNA damage/repair imbalance may contribute to increased risk of lung carcinoma in COPD.

Unbalanced oxidant-induced DNA damage and repair in COPD: A link towards lung cancer

CARAMORI, Gaetano
Co-primo
;
CASOLARI, Paolo;PAPI, Alberto
Ultimo
2011

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is characterised by oxidative stress and increased risk of lung carcinoma. Oxidative stress causes DNA damage which can be repaired by DNA-dependent protein kinase complex. Objectives: To investigate DNA damage/repair balance and DNA-dependent protein kinase complex in COPD lung and in an animal model of smoking-induced lung damage and to evaluate the effects of oxidative stress on Ku expression and function in human bronchial epithelial cells. Methods: Protein expression was quantified using immunohistochemistry and/or western blotting. DNA damage/repair was measured using colorimetric assays. Results: 8-OH-dG, a marker of oxidant-induced DNA damage, was statistically significantly increased in the peripheral lung of smokers (with and without COPD) compared with non-smokers, while the number of apurinic/apyrimidinic (AP) sites (DNA damage and repair) was increased in smokers compared with non-smokers (p=0.0012) and patients with COPD (p<0.0148). Nuclear expression of Ku86, but not of DNA-PKcs, phospho-DNA-PKcs, Ku70 or γ-H2AFX, was reduced in bronchiolar epithelial cells from patients with COPD compared with normal smokers and non-smokers (p<0.039). Loss of Ku86 expression was also observed in a smoking mouse model (p<0.012) and prevented by antioxidants. Oxidants reduced (p<0.0112) Ku86 expression in human bronchial epithelial cells and Ku86 knock down modified AP sites in response to oxidative stress. Conclusions: Ineffective DNA repair rather than strand breakage per se accounts for the reduced AP sites observed in COPD and this is correlated with a selective decrease of the expression of Ku86 in the bronchiolar epithelium. DNA damage/repair imbalance may contribute to increased risk of lung carcinoma in COPD.
2011
Caramori, Gaetano; Adcock, I. M.; Casolari, Paolo; Ito, K.; Jazrawi, E.; Tsaprouni, L.; Villetti, G.; Civelli, M.; Carnini, C.; Chung, K. F.; Barnes, ...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/1422117
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