The dynamic yin-yang interaction of CXCR4 and CXCR7 in breast cancer metastasis

The contribution of CXCR7 to the tumor microenvironment has introduced a new level of complexity to CXCL12 signaling in breast cancer. In the previous issue of Breast Cancer Research, Hernandez and colleagues delineate the roles of CXCR4 and CXCR7 in tumor invasion and metastasis. The authors demonstrate that co-expression of CXCR7 and CXCR4 results in inhibition of CXCL12-mediated invasion, reduced intravasation of tumor cells into the vasculature, and fewer lung metastases compared with parental tumors. The results of this study suggest the combination of small molecule inhibitors of CXCR4 and CXCR7 could dramatically reduce invasion, intravasation, and metastasis and could be highly beneficial for the treatment of invasive breast cancer.