ABSTRACT
Drug resistance is one of the principal limitations in clinical oncology and the cause of recurrence in many patients. Resistance to conventional treatments makes it difficult to treat patients and worsens the prognosis. Cancer stem cells (CSCs) are a subpopulation of tumor cells thought to be largely responsible for gene expression heterogeneity in tumors. In many cases, resistance to treatments and metastasis depend on tumor CSCs. Therefore, given the capacity of the surviving CSCs to regenerate tumor deposits, the radio- and chemoresistance of CSCs constitutes a major clinical concern. Numerous studies show that melatonin, whose antiproliferative properties have been demonstrated in a wide variety of tumors, has important oncostatic properties. Melatonin directly inhibits the proliferation and growth of tumors in several types of cancer. In light of all these properties, melatonin can be considered a therapeutic alternative for different types of cancer. In this review, we propose that cancer diseases be viewed from a cancer stem cell perspective and that melatonin be used as a therapeutic alternative in the treatment of this pathology in order to decrease chemo- and radioresistance and prevent adverse effects of these treatments.
