New Approaches to the Study of Selenium’s Chemopreventive Properties

Abstract

Selenium (Se) compounds, both inorganic and organic, are potent inhibitors of mammary cancer in rodent model systems (1). The new organic compounds, such as selenobetaine and selenomethylseleno-cysteine are more effective than Na₂SeO₃ on a ppm basis (1,2). The salient features of selenium-mediated inhibition of mammary carcinogenesis appear to be the reversibility of the inhibition and the effectiveness of the compounds during either initiation or promotion stages (3). The reversibility of selenium’s inhibitory effect is also observed during Se-mediated inhibition of mammary cell growth in vitro (3). The basis of the inhibition of mammary carcinogenesis in situ and cell growth in vitro is not understood. Although several mechanisms of Se-mediated inhibition have been proposed, i.e., the modulation of DNA synthesis (4), RNA synthesis (5) and glutathione metabolism (6), the evidence of any of these having a central role is not extensive.