Molecular ASpects of Chemical RadiOSensitization

概要

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The low sensitivity of most solid tumors to ionizing radiations is due in part to the low oxygen content within the malignant cells. Attempts to overcome this radioresistance through the use of hyperbaric oxygen and of neutron beams in radiotherapy have been at least in part disappointing. A more promising approach has been the search for chemical compounds which would act as efficient sensitizers of hypoxic cells. A variety of chemicals was found to sensitize bacterial and mammalian cells to radiations in vivo. However such radiosensitizers have been shown to be less efiicient in vivo experiments. These compounds must have favourable pharmacological and toxicological properties such as good specificity for the poorly oxygenated cells, fast diffusion and penetration at a sufficient concentration into the tumor cells, absence of toxicity at therapeutic doses for normal tissues and high resistance to metabolic degradation. The cellular mode of action of these radiosensitizing drugs remains obscure. However the radiosentization may be accounted for either by radiation biochemical or (and) by chemical mechanisms. Diamide and N-ethyl maleimide or NEM which respectively may oxidize and bind to sulfhydryl compounds act mainly through the former mechanism.
日本放射線影響学会の論文