γH2AX as a novel endpoint to detect DNA damage: Applications for the assessment of the in vitro genotoxicity of cigarette smoke

Histone H2AX is rapidly phosphorylated to become gamma H2AX after exposure to DNA-damaging agents that cause double-strand DNA breaks (DSBs). gamma H2AX can be detected and quantified by numerous methods, giving a direct correlation with the number of DSBs. This relationship has made gamma H2AX an increasingly utilised endpoint in multiple scientific fields since its discovery in 1998. Applications include its use in pre-clinical drug assessment, as a biomarker of DNA damage and in in vitro mechanistic studies. Here, we review current in vitro regulatory and non-regulatory genotoxicity assays proposing the gamma H2AX assay as a potential complement to the current test battery. Additionally, we evaluate the use of the gamma H2AX assay to measure DSBs in vitro in tobacco product testing. (C) 2012 Elsevier Ltd. All rights reserved.