The findings show that 3,3'-diindolylmethane (DIM), which is obtained by eating cruciferous vegetables in the Brassica genus, acts as a powerful anti-androgen that inhibits the proliferation of human prostate cancer cells in culture tests.
"As far as we know, this is the first plant-derived chemical discovered that acts as an anti-androgen," said Leonard Bjeldanes, professor and chair of nutritional sciences and toxicology at UC Berkeley's College of Natural Resources and principal investigator of the study. "This is of considerable interest in the development of therapeutics and preventive agents for prostate cancer."
Vegetables such as broccoli, Brussels sprouts, kale and cauliflower are rich sources of indole-3-carbinol (I3C), which the body converts into DIM during digestion. Over the years, Bjeldanes has been researching the anti-cancer properties of dietary indoles with co-author Gary Firestone, UC Berkeley professor of molecular and cell biology.
The new study will be published in the June 6 issue of the Journal of Biological Chemistry, but is now available online.
Androgen is an important hormone for the normal development and function of the prostate, but it also plays a key role in the early stages of prostate cancer, which is typically treated with anti-androgen drugs.
In most cases of prostate cancer, the cancer cells develop resistance to androgen and grow independently of the hormone in later stages of the disease.
In the new study, the researchers conducted a series of tests comparing the effects of DIM on androgen-dependent human prostate cancer cells as well as on their androgen-independent counterparts.