Recruitment of Mesenchymal Stem Cells Into Prostate Tumors Promotes Metastasis

Tumors recruit mesenchymal stem cells (MSCs) to facilitate healing, which induces their conversion into cancer-associated fibroblasts that facilitate metastasis. However, this process is poorly understood on the molecular level. Here we show that the CXCR6 ligand CXCL16 facilitates MSC or Very Small Embryonic-Like (VSEL) cells recruitment into prostate tumors. CXCR6 signaling stimulates the conversion of MSCs into cancer-associated fibroblasts, which secrete stromal-derived factor-1, also known as CXCL12. CXCL12 expressed by cancer-associated fibroblasts then binds to CXCR4 on tumor cells and induces an epithelial to mesenchymal transition, which ultimately promotes metastasis to secondary tumor sites. Our results provide the molecular basis for MSC recruitment into tumors and how this process leads to tumor metastasis.