Cruciferous Vegetables, Isothiocyanates, Indoles, and Cancer Prevention

1. Recent studies have shown that vegetables of the Brassica species can contribute to the prevention of cancer. The Brassica vegetables include broccoli, bok choy, cabbage, and Brussels sprouts, to name a few. 2. Brassica-derived compounds tend to induce the expression of batteries of genes involved in cytoprotection, repress the expression of genes involved in carcinogenesis, improve access to DNA, and induce apoptosis. 3. Cruciferous vegetables are known to contain bioactive compounds that activate Nrf2, a possible tumor suppressor, in various cellular models. 4. Isothiocyanates have been found to inhibit the activity of oncogenic transcription factors such as activator protein-1 (AP-1) and nuclear factor kappa B (NFκB). AP-1 is a protein dimer consisting of either Jun-related proteins or heterodimers of Jun and Fos-related proteins. In its active state, AP-1 can bind to the TPA-response element (TRE). Once bound to the TRE, AP-1 recruits factors to regulate the transcription of genes involved in proliferation, differentiation, apoptosis, and angiogenesis. 5. Researchers have started to explore the ability of isothiocyanates and indoles to inhibit COX-2 activity and inflammation in general. In particular, sulforaphane (SUL) has been noted to block inflammatory responses in both cultured RAW 264.7 macrophages (via NFκB inhibition) and mouse BV-2 microglial cells. 6. Cruciferous vegetables intake appears to reduce the risk for colorectal, prostate and possibly renal cancers. To date the available evidence is not as strong for lung, breast, and oral cancers.