Abstract. Cancer is the leading cause of death worldwide.
Although cancer occurs as a localized disease, its morbidity and mortality rates remain high due to the ability of cancer cells to break-off from the primary tumor and spread to distant organs. Currently, chemotherapy is the main treatment for cancer; however, the increase in proportion of drug-resistant cancer cells and unpleasant side-effects of chemotherapy are still the major challenges in cancer therapy. Curcumin is a natural polyphenol compound and the main bioactive constituent of Indian spice turmeric, widely used in Indian and Chinese medicines. Curcumin has well-known therapeutic actions, including antiinflammatory, anti-microbial, anti-oxidant and anti-cancer properties. Curcumin induces cancer cell apoptosis through regulating various signaling pathways and arresting tumor cell cycle. Curcumin's therapeutic/ preventative actions on metastatic cancers have not been yet fully understood and studied. The present review explores the potential anti-metastatic mechanisms of curcumin, including inhibition of transcription factors and their signaling pathways (e.g., inflammatory cytokines (e.g., CXCL1, CXCL2, multiple proteases (e.g., uPA, MMPs), multiple protein kinases (e.g., MAPKs, FAK), regulation of miRNAs (e.g., miR21, miR181b)
and heat shock proteins (HLJ1). In addition, possible synergistic actions of combination therapy of curcumin with current chemotherapies are discussed in this review.Despite all recent advances in oncology, cancer is still one of the deadliest diseases around the world (1). Cancer occurs as a localized disease but can spread to distant organs through migration, invasion and metastasis (2). Metastatic cancer is one of the major causes of death in cancer patients. Metastasis is a complex process involving multiple steps: (i) local migration through degrading basement membrane and extracellular matrix (ECM), (ii) intravasation into blood and/or lymphatic vessels, (iii) circulating to the target organ site, (iv) extravasation into target organ tissue and, finally, (v) multiplication in the target organ (2, 3). These steps are mediated by various factors, including growth factors, proteolysis degradation of extracellular matrix, cell-cell adhesion, cytoskeleton remodeling and changes of genes' expressions (2, 3). Metastasis is a non-random process that means each metastatic cancer type has its own preferred site of metastasis. For example, breast cancer cells preferentially metastasize to regional lymph nodes, liver, lungs and bone (4). Nowadays, there are different therapeutic approaches available for patients with metastatic cancers, including surgery, radiotherapy and chemotherapy. Chemotherapy remains the main treatment modality for cancer patients because of its ability of preventing invasion and metastasis. However, the morbidity and mortality rates in patients with metastatic cancer still remain high since current chemotherapy agents fail to selectively and effectively kill cancer cells without destroying normal ce...