In the November 1, 2008 issue of The Prostate, researchers at the University of Wisconsin report their finding that a combination of vitamin C and E administered to human prostate cancer cell cultures results in apoptosis (programmed cellular self-destruction). The finding adds support to the hypothesis that vitamin E and selenium are of value in prostate cancer prevention, which is being investigated by the twelve-year Selenium and Vitamin E Chemoprevention Trial (SELECT) of over 32,000 healthy men. For the current study, Nihal Ahmad, PhD and colleagues added varying concentrations of alpha-tocopherol succinate (vitamin E), a form of selenium known as methylselenic acid, or both nutrients to three human prostate cancer cell lines as well as normal prostate epithelial cells. While vitamin E succinate or selenium alone modestly inhibited the growth and viability of prostate cancer cells, the combination of the two dramatically inhibited prostate cancer cell growth while having no effect on either growth or viability of normal cells.
The scientists determined that the nutrients' mechanism involves proteins that are members of the Bcl-2 family, which participate in the control of apoptosis. Apoptosis occurred in all cell lines used in the study, two of which were androgen-insensitive and defective for p53. The finding is important because prostate cancer undergoes a transition from androgen-sensitive to androgen-insensitive disease, and most prostate cancers contain both types of cells.
"We have found that the combination of vitamin E succinate and methylselenic acid was much more effective than either of the agents alone," the authors conclude. "Also, we have used low concentrations of both the agents which makes our finding more relevant to in vivo [living] settings."