Abstract:
Previous studies at UiO have investigated the clonogenic survival of T98G brain cancer (glioblastoma multiforma) cells at different positions on the proton track. From these, a correlation between RBE and LET was found. The main objectives of the present cell irradiation experiments have been to study the mechanisms underlying the known survival data, by recording the amount of unrepaired DNA double strand breaks (DSB) and apoptotic fraction as a function of time after irradiation. DSB levels were measured by flow cytometry using anti-body staining of phosphorylated histone H2AX, a well-established marker of DSBs. Apoptosis-mediated cell death and cell cycles of the cells was examined using a double staining method with FITC-labeled Annexin-V and Propidium Iodide.