Prostate cancer-derived MSCs (PCa-MSCs) downregulate androgen receptor (AR) signaling in prostate cancer cells by expressing high levels of CCL5, which induce an increase in the prostate CSCs population, resulting in upregulation of matrix metalloproteinase-9 (MMP-9), ZeB-1, CD133 and CXCR4 and enhanced metastatic ability [100]. This evidence concerns the gene MMP9 and prostate cancer.