Quantitative analysis of ATM phosphorylation in lymphocytes.

ABSTRACT: Since many anticancer therapies target DNA and DNA damage response pathways, biomarkers of DNA damage endpoints may prove valuable in basic and clinical cancer research. Ataxia telangiectasia-mutated (ATM) kinase is the principal regulator of cellular responses to DNA double-strand breaks (DSBs). In humans, ATM autophosphorylation at serine 1981 (p-S1981) is an immediate molecular response to nascent DSBs and ionizing radiation (IR). Here we describe the analytical characteristics and fit-for-purpose validation of a quantitative dual-labeled immunoblot that simultaneously measures p-S1981-ATM and pan-ATM in human peripheral blood mononuclear cells (PBMCs) following ex vivo exposure to 2?Gy IR, facilitating the calculation of %p-ATM. To validate our assay, we isolated PBMCs from 41 volunteers. We report that the median basal level of p-S1981-ATM and pan-ATM was 2.4 and 49.5?ng/107 PBMCs, respectively, resulting in %p-ATM of 4%. Following exposure of PBMCs to 2?Gy IR, p-S1981-ATM levels increased 12-fold to 29.8?ng/107 PBMCs resulting in %p-ATM of 63%. Interestingly, we show that PBMCs from women have a 2.6-fold greater median p-S1981-ATM level following IR exposure than men (44.4 versus 16.9?ng/107 cells; p < 0.01). This results in a significantly greater %p-ATM for women (68% versus 49%; p?

SUBMITTER: Bakkenist CJ 

PROVIDER: S-EPMC6708498 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature