A new approach to the detection of DNA damage

A method is described which permits the detection of damage produced in unlabeled DNA by daunorubicin, nitrogen mustard, or radiation. After exposure to one of the agents the cells are embedded in an agarose block and lysed to release the DNA. The agarose block is then transferred to a well in an agarose gel and electrophoresis performed. DNA damage is recognized by the presence of DNA whose molecular weight is less than the DNA of cells not exposed to the damaging agent. By transferring the DNA to a solid phase the DNA can be probed with radiolabeled cDNAs to assess damage in specific genes. DNA damage detected by this method correlates well with a loss in the clonogenic capacity of the cells. This method will permit assessment of biologically meaningful DNA damage in unlabeled clinical specimens.