Natural products targeting cancer stem cells: Implications for cancer chemoprevention and therapeutics.

Cancer, being the leading cause of death in the globe, has been one of the major thrust areas of research worldwide. In a new paradigm about neoplastic transformations, the initiation and recurrence of disease is attributed to few mutated cells in bulk of tumor called cancer stem cells (CSCs). CSCs have capacity of self-renewal and differentiation, which are known for resistance to radio and chemotherapy leading to recurrence of the disease even after treatment. Most of traditional drugs implicated in cancer therapy targeting primary tumors have substantial toxicity to the physiological system and have not been efficient in targeting these CSCs leading to poor prognosis. Targeting these CSCs in bulk of tumor might be novel strategy for cancer chemoprevention and therapeutics. Diet-derived interventions and diverse natural products are known to target these CSCs and related signaling pathways, namely, Wnt, Notch, and Hedgehog pathways, which are implicated for CSC self-renewal. PRACTICAL APPLICATIONS: Cancer remains a global challenge even in this century. Poor prognosis, survival rate, and recurrence of the disease have been the major concerns in traditional cancer therapy regimes. Targeting cancer stem cells might be novel strategy for elimination and cure of the chronic disease as they are known to modulate all stages of carcinogenesis and responsible for recurrence and resistance to chemotherapy and radiotherapy. The evidence support that natural products might inhibit, delay, or reverse the process of tumorigenesis and modulate the different signaling pathways implicated for cancer stem cells self-renewal and differentiation. Natural products have minimal toxicity compared to traditional cancer therapy drugs since they have long been utilized in our food habits without any major side effects reported. Thus, targeting cancer stem cells with natural product might be a novel strategy for drug development in cancer chemoprevention and therapeutics.