Macrophages as prognostic biomarkers in human melanoma

Chemokines produced at the tumor micro-environment can be exploited by tumor cells to proliferate and invade, or may promote tumor growth indirectly by acting on stromal cells. CCR6/CCL20 is a relevant chemotactic axis involved in the progression and dissemination of different human cancers [1]. We have recently shown the existence of a previously unnoticed paracrine loop between stromal CCL20 and tumor CCR6 in primary cutaneous melanoma [2], different to the autocrine loop reported in epithelial tumors [1]. CCL20 expression was largely restricted to the stroma of primary melanomas that eventually developed metastasis, and proved to be a Breslow-independent prognostic factor associated with distant metastasis and worse patient survival. By contrast, we did not find any correlation between tumor CCR6 expression and metastatic dissemination [2]