CXCL13 is androgen-responsive and involved in androgen induced prostate cancer cell migration and invasion

Androgen receptor (AR) is a key transcription factor playing a critical role in prostate cancer (PCa) initiation and progression. However, the molecular mechanisms of AR action in prostate cancer are not very clear. CXCL13, known as B cell attracting chemokine1 (BCA-1), is a member of CXC chemokine family and relevant to cancer metastasis. This study shows that CXCL13 is an androgen-responsive gene and involved in AR-induced PCa cell migration and invasion. In clinical specimens, expression of CXCL13 in PCa tissues is markedly higher than that in adjacent normal tissues. In cultures, expression of CXCL13 is up-regulated by androgen-AR axis at both mRNA and protein levels. Furthermore, Chip-Seq assay identifies canonical androgen responsive elements (ARE) at CXCL13 enhancer and dual-luciferase reporter assays reveals that the ARE is highly responsive to androgen while mutations of the ARE abolish the reporter activity. Additional chromatin immunoprecipitation (ChIP) assays also identify that the ARE presents androgen responsiveness. In addition, CXCL13 promotes G2/M phase transition by increasing Cyclin B1 levels in PCa cells. Functional studies demonstrate that reducing endogenous CXCL13 expression in LNCaP cells largely weakens androgen-AR axis induced cell migration and invasion. Taken together, our study implicates for the first time that CXCL13 is an AR target gene and involved in AR-mediated cell migration and invasion in primary PCa.