Low Energy Proton Beam Induces Efficient Cell Killing in A549 Lung Adenocarcinoma Cells

The aim of the current study was to determine the signaling differences between γ- and proton beam-irradiations. A549 lung adenocarcinoma cells were irradiated with 2 Gy proton beam or γ-radiation. Proton beam was found to be more cytotoxic than γ-radiation. Proton beam-irradiated cells showed phosphorylation of H2AX, ATM, Chk2, and p53. The mechanism of excessive cell killing in proton beam-irradiated cells was found to be upregulation of Bax and downregulation of Bcl-2. The noteworthy finding of this study is the biphasic activation of the sensor proteins, ATM, and DNA-PK and no activation of ATR by proton irradiation.