Cabbage related ingredient (DIM) may help chemotherapy fight advanced prostate cancer

One of the ingredients that make cabbage, broccoli, and related vegetables so healthy and protective is their content of I3C. I3C has cancer fighting activities mostly because it is converted to a metabolite known as DIM (3,3'-Diindolylmethane). In this new study scientists from the Karmanos Cancer Institute, Wayne State University School of Medicine show that DIM enhances the drug Taxoteres ability to kill advanced prostate cancer cells (hormone-refractory prostate cancer cells). DIM achieves this through down-regulation of survivin. Survivin is a protein expressed highly in most human tumors. Survivin prevents the cancer from dying. Survivin is associated with both prostate cancer progression and resistance to treatment by drugs.

The researchers hypothesized that survivin may play a potentially important role in hormone-refractory prostate cancer (HRPC) and bone metastatic disease (when prostate cancer colonizes in bone). They investigated the effect of DIM alone or in combination with Taxotere using LNCaP and C4-2B prostate cancer cells. They found that DIM enhanced Taxotere-induced apoptotic death in both cell lines (the ability of Taxotere to kill both varieties of prostate cancer cell). These enhancing effects were related to a decrease in survivin expression as well as androgen receptor and nuclear factor-kappaB (NF-kappaB) DNA-binding activity.

Importantly, assays showed a significant reduction of survivin-Luc and NF-kappaB-Luc activity in prostate cancer cells exposed to DIM and Taxotere. Furthermore, combination treatment significantly inhibited C4-2B bone tumor growth, and the results were correlated with the down-regulation of survivin. From these results, the researchers conclude that inactivation of survivin by DIM enhanced the therapeutic efficacy of Taxotere in prostate cancer in general, which could be useful for the treatment of HRPC and metastatic prostate cancer. The study is published online ahead of print May 12, 2009 in the journal Cancer Research.