NEW YORK (Reuters) -- The decreased production of male hormones associated with aging may raise older men's risk of prostate cancer, researchers say.
Researchers at University of Wisconsin Comprehensive Cancer Center say that understanding the role of male sex hormones, or androgens, in regulating cell activity "could potentially provide information on how to regulate, or prevent, certain age- and hormone-associated diseases, including cancer."
The link may lie in the ability of androgen to activate substances known as antioxidants. Antioxidants include vitamins A, C and E, and enzymes such as glutathione peroxidase and catalase. Recent studies have suggested that antioxidant activity inhibits the production of potential cancer-causing agents in cells.
Researchers introduced androgens, such as naturally occurring testosterone DHT and the synthetic androgen R1881, into two types of prostate cancer cell groups. One type -- DU145 -- "did not respond to androgens in terms of growth." But the second cell group -- LNCaP cells -- "responded to androgens in various ways, depending on the dose."
Scientists believe that LNCaP cells have a special genetic 'receptor' that allows androgens to lock onto the cell and thus influence its patterns of activity. DU145 cancer cells seem to lack this essential receptor.
The androgen-treated LNCaP cells showed lowered levels of "oxidative stress" when compared with cancer cells not subjected to male hormones. Oxidative stress refers to a biochemical condition resulting from decreased levels of antioxidants (vitamins and enzymes) on high levels of potentially destructive oxidants. The hormones seem to reduce the activity of the mitochondria -- the cell's energy- (and oxidant) producing 'powerhouse', researchers say. Hormone-treated cells were found to have reduced levels of various chemicals, including glutathione, which "taken together all provide an important cellular defense against oxidative stress."
The researchers suggest their study may be an important first step in understanding how reduced levels of male hormones in older men may influence their risk for developing prostate cancer.
In a commentary on the study, published in the Journal of the National Cancer Institute, Dr. Joachim Liehr of the University of Texas Medical Branch in Galveston, notes that the cells studied were grown in an atmosphere consisting of 5% carbon dioxide and 95% air. Cells grown in such conditions "may be stressed by this high oxygen environment," and for this reason he urges further research which could exclude any influence those conditions might have had on the University of Wisconsin results.
The American Cancer Society lists prostate cancer as the second leading cause of cancer death in men, killing 41,400 Americans in 1996.
SOURCE: Journal of the National Cancer Institute (1997;89(1):3-4, 40-47)
