It's previously been established that the dietary mineral selenium can reduce the incidence of prostate cancer by acting as an antioxidant when incorporated into proteins. But researchers don't understand how it does this. "The problem is, nobody seems to know how the mechanism works, and that's not trivial," said researcher Alan Diamond, at the University of Illinois at Chicago (UIC). To help answer that question, Diamond is heading-up an ongoing multidisciplinary study at UIC. "Knowing how it works [will allow us] to maximize-out its benefits," he said.
Some of Diamond's work has just been published in the Proceedings of the National Academy of Sciences, where he reports on research using specially bred transgenic mice that suggest it is the level of selenium-containing proteins in the body that is instrumental in preventing cancer, and that dietary selenium plays a significant role in stimulating the body's levels of these "selenoproteins".
In his experiment, Diamond mated two genetically manipulated mice; where one was prone to developing prostate cancer, and the other had lower levels of selenoproteins. Fifty offspring that carried both of the parents' traits were then studied to see if the reduced levels of selenoproteins accelerated cancer development. As was suspected, it did. "It's a hardcore link in an animal model system of selenium-containing proteins to prostate cancer and, by extrapolation, the mechanism by which selenium prevents cancer," said Diamond.
More research is underway to corroborate the anti-cancer effect of dietary selenium, but much work remains to be done to discover exactly how selenoproteins play their protective role. Diamond explained that at least 25 different selenoproteins have been found in the human body, but what role each plays is not known.
Diamond speculates that the effectiveness of selenium may be due to its effects on a single selenoprotein; or, combinations of several members of this class. One selenoprotein in particular - glutathione peroxidase - is of special interest to Diamond. They plan to run tests using new mice genetically modified to reduce levels of just this one selenoprotein. "If reductions result in accelerated prostate cancer, then we have our player," Diamond said.
Based on material from the University of Illinois at Chicago
