Plants vs. cancer: a review on natural phytochemicals in preventing and treating cancers and their druggability

Abstract

Cancer remains to be one of the leading causes of death in the United States and around the world. The advent of modern drug-targeted therapies has undeniably improved cancer patients' cares. However, advanced metastasized cancer remains untreatable. Hence, continued searching for a safer and more effective chemoprevention and treatment is clearly needed for the improvement of the efficiency and to lower the treatment cost for cancer care. Cancer chemoprevention with natural phytochemical compounds is an emerging strategy to prevent, impede, delay, or cure cancer. This review summarizes the latest research in cancer chemoprevention and treatment using the bioactive components from natural plants. Relevant molecular mechanisms involved in the pharmacological effects of these phytochemicals are discussed. Pharmaceutical developmental challenges and opportunities in bringing the phytochemicals into the market are also explored. The authors wish to expand this research area not only for their scientific soundness, but also for their potential druggability.

Figure 1

Regulation of Nrf2-mediated gene transcription by phytochemicals. Under homeostatic condition, Nrf2 is retained in the cytoplasm by Keap1 protein. Chemopreventive phytochemicals interact directly with the cysteine residues of Keap1 to trigger the release Nrf2 from the complex. Chemopreventive agent-generated electrophiles or reactive oxygen species can activate a wide variety of kinase signaling pathways, including PI3K, PKC, MAPK, all of which can trigger the release and translocation of Nrf2 from cytosal to nuclear.