Relevance of the radioprotective effect of natrium selenite. Preclinical results

Material and Method: Based on the mode of action of Na2SeO3 as a radical sc avenger in vitro culture experiments using normal human skin fibroblasts an d squamous cell carcinoma cells were performed to investigate the potential role of Na2SeO3 as a radioprotector for normal cells. Therefore, comparati ve studies of combined treatment, i.e. radiation exposure +/- Na2SeO3 in si ngle-dose (0 to 7 Gy) and multiple fractionated-dose (5 x 2 Gy), were appli ed to differentiate the radiation response of normal and tumor cells depend ing upon the treatment protocol. Results: The results indicate that Na2SeO3 under both radiation exposure co nditions positively modulates the radiation response of normal fibroblasts in sense of the radioprotective effect. On the contrary, human tumor cells are not affected by the radioprotective capacity of Na2SeO3 neither under s ingle-dose nor fractionated-dose irradiation. Conclusion: On the basis of the quantitative cell culture analyses, this st udy indicates for the first time the potential role of Na2SeO3 as a radiopr otective compound for normal cells. It will be discussed to what degree dif ferential expression of apoptotic cell death in normal and tumor cells cont ributes to the radiation response of normal and tumor cells.