Signal Transduction Events Elicited by Natural Products that Function as Cancer Chemopreventive Agents

Abstract
Cancer chemoprevention is a rapidly emerging paradigm for slowing, stopping or reversing the carcinogenic process. A multiplicity of biological mechanisms, functioning as complex interactions of gene products and regulatory pathways, are stimulated or inhibited by cancer chemopreventive agents. Several natural products and dietary components have been shown to function as chemopreventive agents. Screening chemical libraries of natural products for properties associated with cancer chemoprevention provides important insight into structural motifs driving rational design of more effective agents. In this review, the signal transduction pathways that are modulated by chemopreventive natural products are summarized. The activation of several signal transduction pathways triggered by polyphenolic antioxidants, flavonoids, retinoids, phytoestrogens and isothiocyanates are illustrated. These natural products may disrupt many signaling pathways, including transduction of cell surface (epidermal growth factor) or ...