CAFs and TAMs: maestros of the tumour microenvironment.

Many non-tumour host cells such as inflammatory cells, fibroblasts, and endothelial cells are present in the tumour microenvironment and affect the malignant potential and chemo-resistance of the tumour cells. Macrophages and fibroblasts are the main components of infiltrating stromal cells and are referred to as tumour-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs), respectively. TAMs and CAFs are reported to be involved in tumour progression, although their functions change to those of an anti-tumour phenotype under specific conditions. Notably, recent work published in The Journal of Pathology by Hashimoto and colleagues provided critical evidence indicating the significance of collaboration between TAMs and CAFs for tumour progression. They showed that cell-cell interaction between these two cell types induced recruitment and activation of each other, and that the combined activities of these cells were involved in neuroblastoma progression. Although many research groups are now interested in the significance of stromal cells such as CAFs and TAMs for tumour progression, only a few studies have been published describing the cell-cell interactions of these cells. Cell-cell interactions of stromal cells potentially play important roles in tumour progression and should be a focus for further oncology research.