Mechanisms and therapeutic implications of cell death induction by indole compounds.

Indole compounds, obtained from cruciferous vegetables, are well-known for their anti-cancer properties. In particular, indole-3-carbinol (I3C) and its dimeric product, 3,3´-diindolylmethane (DIM), have been widely investigated for their effectiveness against a number of human cancers in vitro as well as in vivo. These compounds are effective inducers of apoptosis and the accumulating evidence documenting their ability to modulate multiple cellular signaling pathways is a testimony to their pleiotropic behavior. Here we attempt to update current understanding on the various mechanisms that are responsible for the apoptosis-inducing effects by these compounds. The significance of apoptosis-induction as a desirable attribute of anti-cancer agents such as indole compounds cannot be overstated. However, an equally intriguing property of these compounds is their ability to sensitize cancer cells to standard chemotherapeutic agents. Such chemosensitizing effects of indole compounds can potentially have major clinical implications because these non-toxic compounds can reduce the toxicity and drug-resistance associated with available chemotherapies. Combinational therapy is increasingly being realized to be better than single agent therapy and, through this review article, we aim to provide a rationale behind combination of natural compounds such as indoles with conventional therapeutics.