Dietary cancer-chemopreventive compounds: from signaling and gene expression to pharmacological effects

The process of cancer development (carcinogenesis leading to advanced metastasized cancers) in humans generally takes many years through initiation, promotion and progression. Because advanced metastasized cancers are almost impossible to treat, cancer chemoprevention for the control and containment of early cancer development is highly desirable. Recent studies have provided strong evidence that many daily-consumed dietary compounds possess cancer-protective properties that might interrupt the carcinogenesis process. These properties include the induction of cellular defense detoxifying and antioxidant enzymes, which can protect against cellular damage caused by environmental carcinogens or endogenously generated reactive oxygen species. These compounds can also affect cell-death signaling pathways, which could prevent the proliferation of tumor cells. In this review, we will summarize current knowledge on dietary cancer-chemopreventive compounds and their induction of detoxifying enzymes and anti-proliferative effects, and discuss the challenges in translating these signaling and gene-expression events to pharmacological effects.