Purpose: Reduced glutathione (GSH) is an endogenous thiol and has long been thought to affect the sensitivity of cells to radiation. The aim was to see the influence of GSH on: (i) the production of all types of radiation-induced chromosome aberrations (CA), and (ii) the radiation-induced delay in cell cycle and the levels of cell cycle regulator proteins.
Materials and methods: Cell cycle kinetics were determined by scoring the mitotic index (MI). CA and MI were scored in gamma-irradiated buthionine sulfoximine (BSO) (10 h) or GSH (1 h) pretreated and untreated mouse bone marrow cells (BMC). The expression of p53 and p21 proteins after 2 and 6 h of irradiation and for the B-cell lymphoma 2 (Bcl-2) associated X-protein (Bax) after 24 h of irradiation with or without BSO or GSH treatment was analyzed by immunoblotting.
Results: Radiation delays mouse BMC in their passage through the cell cycle and induces CA. Exogenous addition of GSH protected CA uniformly at lower doses of radiation but differentially at higher doses, whereas GSH-depletion by BSO increased the frequency of radiation-induced CA. Both GSH and BSO-pretreated cells reduced the delay in cell kinetics after irradiation. Levels of both p53 and p21 were enhanced after irradiation to BSO-pretreated cells. However, in GSH-pretreated cells the level of these proteins was reduced.
Conclusion: Data indicate that the induction of CA and delay in cell kinetics by radiation may not always be interlinked and that the level of endogenous GSH exerts its influence on these parameters. Both GSH and BSO pretreatment reduce delays in cell kinetics of irradiated cells which may die apoptotically, since they have either a higher frequency of exchange aberrations or CA, respectively.