The need for dynamic methods for measuring cell cycle perturbations: a study in radiation-treated lymphoblastoid cell lines of varying p53 status

Reports on the p53-related cell cycle and apoptotic responses of EBV-transf ormed lymphoblastoid cell lines to DNA damage have led to some confusion. T his may be due to differences in the nature of the specific p53 mutations u nder examination, but it can also be partly attributed to methodological an d analytical problems (e.g. the inappropriate use of static DNA histograms for cell cycle analysis). Taking seven lymphoblastoid cell lines derived fr om both normal individuals and Li-Fraumeni Syndrome/Li-Fraumeni-Like (LFS/L FL) patients of differing p53 status, we completed a detailed study of radi ation-induced cell cycle perturbations. Using BrdUrd pulse labelling and fl ow cytometry it was found that? regardless of p53 status, the cells did not arrest in G(1) despite all of the lines showing p53 upregulation 3 hours p ostirradiation. The irradiated cells did, however, show a general slowing b oth in S-phase entry from G(1) and in movement through S-phase. These facts would not have been apparent from the analysis of static DNA histograms. T he problems with the use of static methods to assess changes in the dynamic s of cell cycle progression apply not only to studies involving EBV-transfo rmed cell lines, but also to a wide range of investigations into the molecu lar control of cell proliferation.