Abstract
DNA double strand break (DSB) is the most destructive damage caused by ionizing radiation and can lead to cell death and transformation if not repaired properly. The premature chromosome condensation (PCC) assay using cell fusion is a sensitive method to detect DSB at the chromosome level especially in G1 cells. However, the occurrence of repair during the incubation period of this method lowers its sensitivity. By using a DSB repair inhibitor, wortmannin (WM) during this critical period, we have improved the sensitivity of the PCC assay. Normal human fibroblasts were X-ray irradiated under cold condition and immediately fused with mitotic HeLa cells using Hemagglutinating virus of Japan envelop (HVJ-E). Wortmannin was added just before incubation of the PCC procedure. After 1 hour, cells were fixed and stained with Giemsa and was observed under light-microscope. We have observed almost twice as many chromosome breaks in WM treated cells as compared with cells without WM. We also were able to measure repair of chromosome breaks with X-ray doses less than 0.5 Gy. [J Radiat Res 44:400 (2003)]
