Epithelial-to-Mesenchymal Transition: Liaison between Cancer Metastasis and Drug Resistance

Metastasis and drug resistance are two of the leading causes of death in cancer patients. Poor responses to antitumor drugs can lead to tumor cell dissemination and metastasis. On the other hand, cells that metastasize to lymph nodes and distant organs are liable to drug resistance. Recently, the epithelial-mesenchymal transition (EMT) has been found to play a critical role in cancer metastasis and drug resistance; however, the underlying and intrinsic links between them remain unclear. In this review, we summarize recent advances in tumor metastasis and drug resistance, and we focus especially on the association between EMT, metastasis, and drug resistance. We discuss the molecular mechanisms and potential pathways involved in the regulation of EMT, focusing simultaneously on the roles of EMT in modulating metastasis and drug resistance, especially the nature of their intrinsic links across different types of cancer.