Caffeine treatment enhances low dose γ-irradiation- induced chromatid-type aberrations in human leukaemia cells, but not in human normal fibroblast cells in culture

We investigated the effect of caffeine on low dose γ -radiationinduced chromosomal damage in human T-cell leukaemia cells (Jurkat T-cells) and two normal human fibroblast cell lines (AG1522 and GM2149). Low doses of gamma-radiation were found to increase the levels of chromatid gaps and breaks in a dose-dependent manner in both normal and cancer cells; however, cancer cells appeared to be more sensitive than the normal cells. Caffeine treatment before radiation exposure significantly increased the levels of chromatid gaps and breaks in Jurkat T-cells at all radiation doses, but it did not increase the level of these aberrations in normal cells. The mechanisms of this differential effect of caffeine in cancer cells and normal cells are unknown; however, G2-delay allows more time for rejoining of chromosome breakage to occur, then elimination of this delay by caffeine in tumour cells, not in normal cells might account for difference.