Synthetic dimer of indole-3-carbinol: Second generation diet derived anti-cancer agent in hormone sensitive prostate cancer

BACKGROUND. Cruciferous vegetables have been found to have anti-prostate cancer effects. The active compounds mediating these effects include indoles such as indole-3-carbinol (I3C) and isothiocyanates. I3C is unstable having tissue tropic effects and clinical utility has been partly addressed by the synthesis of a more stable dimer diindolylmethane (DIM). METHODS. Anti-proliferative activity was measured by XTT assay and cytosolic proteins quantitated by Western blot analysis. RESULTS. DIM (IC50 50 mu M) is a better anti-proliferative agent than I3C (IC50 150 mu M) in androgen dependent LNCaP cells, inhibits DNA synthesis, and growth of R1881 stimulated LNCaP cells. Androgen receptor (AR), cyclin D1, and cdk4, induced by R1881, are downregulated by DIM. DIM downregulates phosphorylated Akt and phosphatidyl inositol 3-kinase and downstream inhibition of cyclin D1 and cdk4. CONCLUSION. These studies provide evidence that DIM is a second-generation chemopreventive agent with a viable cellular target and has clinical potential as an anti-prostate cancer chemopreventive. Prostate 66: 453-462, 2006. (c) 2005 Wiley-Liss, Inc.