Radiation-induced damage in two human glioma cell lines as measured by the nucleoid assay

We measured radiation-induced damage and repair in MO59J and MO59K human glioma cell lines using the nucleoid halo assay. Although these two cell lines have different radiosensitivities when assayed for colony forming efficiency, our results indicated that there was no significant difference between the two in terms of the unwinding and rewinding of DNA supercoils, radiation-induced changes in nucleoid halo size or the kinetics of nucleoid halo lysis. The only differences noted were in the kinetics of recovery of radiation-induced changes in nucleoid halo size, with the more sensitive cell line (MO59J) showing a slightly faster recovery than the more resistant cell line (MO59K). However, this difference was not statistically different. Our data indicate that the different cellular radiosensitivities of MO59J and MO59K cells are probably not due to any differences in their supercoiled DNA structure as measured by the nucleoid halo assay.