Anticancer Properties of Curcumin

Curcumin is a major biological active compound from turmeric or Curcuma longa. This nontoxic natural compound has been reported to possess several biological activities that are therapeutically beneficial to cancer treatment. It has been reported to increase the efficacy of other chemotherapeutic agents and to reduce their toxic side effects which are the major drawback of most chemotherapeutic agents. Curcumin is also well known for its antiinflammatory activity (Amanda and Robert, 2008). Since cancer often develops under chronic inflammatory conditions, curcumin has the potential to be a preventive treatment agent against cancer. Furthermore, unlike most chemotherapeutic agents which act on a specific process of cancer development, i.e., cell growth or apoptosis, curcumin exerts its effect on various stages of cancer development, i.e., oncogene activation (Singh and Singh, 2009), cancer cell proliferation (Simon et al., 1998), apoptosis evasion (Han et al., 1999), anoikis resistance (Pongrakhananon et al., 2010), and metastasis (Chen et al., 2008) (Figure 1). Therefore, curcumin has the potential to overcome chemoresistance which is a major problem in cancer chemotherapy. This chapter will provide an overview of the anticancer activities of curcumin and present pre-clinical and clinical evidence supporting the use of curcumin as an anticancer agent. Cancer is known to be associated with genetic instability in which c-myc serves as a major modifier of many targeted genes (Mai and Mushinski, 2003). Likewise, the mutation of proto-oncogene ras has been identified in many types of tumor (Rajalingam et al., 2007). The dysregulation of these oncogenes is well recognized as an initial step in the development of tumorigenesis. Interestingly, curcumin has been reported to have a suppressive effect on the oncogenes and inhibit their downstream effectors such as cell cycle promoting and proapoptotic proteins (Singh and Singh, 2009). Curcumin also exhibits anticancer properties through its ability to inhibit cell proliferation and induce apoptosis. The anti-proliferative effect of curcumin is dependent on its concentration, duration of treatment, and specific cell type. At low doses, curcumin causes cell cycle arrest, while at higher doses it induces apoptosis. Cell proliferation is controlled by several cell cycle regulating proteins, notably the family of cyclin and cyclin-dependent kinases (Kastan and Bartek, 2004) whose expression is tightly associated with tumorigenesis (Diehl, 2002). Curcumin inhibits cell cycle progression by downregulating cyclin D1 and the transition from G1 to S phase in