Curcumin and colorectal cancer: An update and current perspective on this natural medicine

Colorectal cancer (CRC) is one of most common malignancies worldwide and its incidence is still growing. In spite of recent advances in targeted therapies, their clinical efficacy has been limited, non-curative and unaffordable. A growing body of literature indicates that CRC is a multi-modal disease, where a variety of factors within the tumor microenvironment play a significant role in its pathogenesis. For instance, imbalance in gut microbial profiles and impaired intestinal barrier function contribute to the overall intestinal inflammation and initiation of CRC. Moreover, persistent chronic inflammation favors a tumor microenvironment for the growth of cancer. In addition, autophagy or 'self-eating' is a surveillance mechanism involved in the degradation of cellular constituents that are generated under stressful conditions. Cancer stem cells (CSCs), on the other hand, engage in the onset of CRC and are able to endow cancer cells with chemo-resistance. Furthermore, the aberrant epigenetic alterations promote CRC. These evidences highlight the need for multi-targeted approaches that are not only safe and inexpensive but offer a more effective alternative to current generation of targeted drugs. Curcumin, derived from the plant Curcuma longa, represents one such option that has a long history of its use for a variety of chronic disease including cancer, in Indian ayurvedic and traditional Chinese medicine. Scientific evidence over the past few decades have overwhelmingly shown that curcumin exhibits a multitude of anti-cancer activities orchestrated through key signaling pathways associated with cancer. In this article, we will present a current update and perspective on this natural medicine - incorporating the basic cellular mechanisms it effects and the current state of clinical evidence, challenges and promise for its use as a cancer preventative and potential adjunct together with modern therapies for CRC patients.