Inorganic arsenic (iAs), a known human carcinogen, induces oxidative DNA damage and epigenetic silencing of tumor suppressor genes related to tumor progression. Chromodomain-helicase-DNA-binding protein 4 (CHD4) is a chromatin remodeling protein that acts on DNA repair and DNA methylation under oxidative damage in malignancies, but the role of CHD4 in arsenical urothelial carcinoma (UC) is unidentified. Our purpose was to observe CHD4-related repair effects on As-stimulated oxidative damage in human UC. The markers of oxidative DNA damage 8-hydroxy-2'-deoxyguanosine (8-OHdG) and CHD4 were investigated by immunohistochemistry in 45 UC tissues from non-blackfoot disease (BFD) areas and BFD areas respectively. The cellular mechanisms of CHD4 involved in the oxidative DNA repair and DNA methylation were evaluated by immunocytochemistry and western blot. The expressions of CHD4 and 8-OHdG were significantly increased in UC patients from the As-exposed areas. The underlying mechanism of CHD4-mediated DNA repair and DNA methylation involved the activation of zinc finger MYND-type containing 8 (ZMYND8) and DNA methyltransferase (DNMTs) in SV-HUC-1, T24 and BFTC-905 cells. These results highlight the potential clinical significance of CHD4 in UCs from BFD areas. The CHD4-mediated oxidative DNA repair and epigenetic DNA methylation in UC cells stimulated by arsenic was revealed. CHD4 might be used as a prognostic indicator in arsenical UC.
Keywords: CHD4; DNA methylation; Inorganic arsenic; Oxidative DNA repair; Urothelial carcinoma.
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