Epidemiological and dietary studies have revealed an association between high dietary intake of cruciferous vegetables and decreased
prostate cancer risk. Our studies have shown that
indole-3-carbinol (I3C), a common
phytochemical in cruciferous vegetables, and its in vivo dimeric product
3,3'-diindolylmethane (DIM) upregulate the expression of phase I and phase II
enzymes, suggesting increased capacity for detoxification and inhibition of
carcinogens. Studies from our laboratory and others have found that I3C can induce G1 cell-cycle arrest and apoptosis in
prostate cancer cells. In addition, we found, by microarray gene expression profiling, that I3C and DIM regulate many genes that are important for the control of cell cycle, cell proliferation, signal transduction, and other cellular processes, suggesting the pleiotropic effects of I3C and DIM on
prostate cancer cells. We recently found that I3C functions as an inhibitor of Akt and
nuclear factor kappaB (
NF-kappaB), which play important roles in cell survival and which are believed to be potential targets in
cancer therapy. Studies have already shown that the inactivation of Akt and
NF-kappaB is responsible for chemosensitization of chemoresistant
cancer cells. Because there is no effective treatment strategy for
hormone-dependent and, most importantly,
hormone-independent and metastatic
prostate cancer, our strategies to sensitize
prostate cancer cells to a chemotherapeutic agent by I3C and DIM is a novel breakthrough that could be used for devising novel
therapies for
prostate cancer. In conclusion, the results from our laboratory and from others provide ample evidence for the benefit of I3C and DIM for the prevention and the treatment of
prostate cancer.