Tumor-associated macrophages and epithelial-mesenchymal transition in cancer: Nanotechnology comes into view.

Tumor-associated macrophages (TAMs) are an important component of the leukocytic infiltrate of the tumor microenvironment. There is persuasive preclinical and clinical evidence that TAMs induce cancer inanition and malignant progression of primary tumors toward a metastatic state through a highly conserved and fundamental process known as epithelial-mesenchymal transition (EMT). Tumor cells undergoing EMT are distinguished by increased motility and invasiveness, which enable them to spread to distant sites and form metastases. In addition, besides becoming resistant to apoptosis and antitumor drugs, they also contribute to immunosuppression and get a cancer stem-cell like phenotype. Here, we will focus on selected molecular pathways underlying EMT-in particular, the role of TAMs in the induction and maintenance of EMT-and further discuss how the targeting of TAMs through the application of nanotechnology tools allows the development of a whole new range of therapeutics.