Modulation of ionizing radiation-induced effects by NU7441, KU55933 and VE821 in peripheral blood lymphocytes
Abstract
We evaluated the impact of ataxia-telangiectasia mutated kinase inhibitor KU55933, DNA-dependent protein kinase inhibitor NU7441 and ataxia telangiectasia and rad3-related kinase inhibitor VE821 in human peripheral lymphocytes in vitro. The lymphocytes were divided into 5 groups: non-irradiated control, irradiated group (2 Gy) and 3 groups pretreated with inhibitors 30 min before irradiation.
We used flow cytometry to evaluate phosphorylated H2AX (gamma-H2AX) and cytotoxicity (Apoptest). Micronucleus assay was used to assess genotoxicity.
After irradiation, gamma-H2AX, incidence of micronuclei (MN), nucleoplasmatic bridges (NPBs) and nuclear buds in binuclear cells, MN in mononuclear cells and apoptosis were increased. KU55933 decreased gamma-H2AX and inhibited ionizing radiation-induced cytotoxicity.
NU7441 showed no effect on gamma-H2AX but it significantly increased MN and NPBs in binuclear cells and apoptosis. VE821 decreased gamma-H2AX, whereas genotoxicity and cytotoxicity were not affected.
In conclusion, KU55933 protected lymphocytes, which might be employed to preserve the immune system during anticancer therapy. NU7441 radiosensitized lymphocytes, thus, undesirable side effects toward immune system could be expected.
VE821 showed decrease of gamma-H2AX with no radiosensitizing effects in our model likely due to p53 positive status, which underlies the concept of its application in p53 negative environment.