Fig. 7.

The antioxidant pathways are activated during EBV infection and are required for growth transformation. Freshly isolated B-lymphocytes infected with the transforming B95-8 strain of EBV were cultured for up to 2 weeks in the presence or absence of MTH1 inhibitors. Protein expression was monitored by western blots, cell proliferation and activation of the DDR were assessed by ³H-Thy incorporation and staining for γH2AX, respectively. a representative western blots illustrating the parallel increase of MTH1 and EBNA1 expression following EBV infection and mean ± SE of the intensity of the MTH1 specific band in five independent experiments. b Representative western blots illustrating the expression of MTH1, MUTYH and OGG1 in ex vivo untreated B-cell and freshly EBV infected and SAC induced B blasts cultured for comparable times and showing similar levels of cell proliferation. c Quantification of the specific bands. Relative expression is the ration between the intensity in the treated cells versus freshly harvested cells. The mean ± SE of three to four independent experiments is shown. d Inhibition of MTH1 prevents the establishment of EBV transformed lymphoblastoid cell lines. ³H-Thy incorporation was measured after culture of freshly EBV infected B-lymphocytes in the presence of the indicated amounts of MTH1 inhibitors. Depending on the condition of the cultures harvesting was done after ten to fifteen days. e Inhibition of MTH1 strongly enhances the induction of DNA damage in freshly EBV infected cells. DNA damage was detected by γH2AX staining. f Mean ± SE of the % γH2AX positive cells in three independent experiments. *P < 0.05; **P < 0.01