Mitosis-targeting natural products for cancer prevention and therapy.

Mitosis is a complex process resulting in division of a cell into two daughter cells, and its failure often results in the death of the daughter cells (via apoptotic, necrotic, or proliferative/senescent death). Many chemicals that inhibit the mitotic process (anti-mitotic drugs) have proven effective for killing cancer cells in vitro and in clinical settings. Among the most studied anti-mitotic drugs are plant-origin natural products including taxanes (e.g. paclitaxel, docetaxel) and vinca alkaloids (e.g. vincristine, vinblastine), whose validated target is the spindle microtubules. With the success of these agents, efforts have been made to develop other spindle poisons as well as to improve efficacy of existing spindle poisons with structural modifications. Novel drugs and natural products that inhibit other proteins involved in mitosis (nonmicrotubule targets) have been sought in hopes of expanding available cancer-directed therapies. Recently, significant advances have been made in the understanding of mitotic mechanisms in tumor cells as well as in normal epithelial cells. These advances help us to identify and develop potential natural agents for the prevention and treatment of cancer. This review will focus on natural products that target mitotic process and/or proteins involved in mitotic progression.