Tumor cell-specific blockade of CXCR4/SDF-1 interactions in prostate cancer cells by hTERT promoter induced CXCR4 knockdown A possible metastasis preventing and minimizing approach

Stromal cell-derived factor-1 (SDF-1)/CXCR4 pathway has been shown to play art important role in prostate cancer (PCa) metastasis and siRNA expression using cell-specific promoters has been demonstrated to be a potential tool for targeted gene therapy. Here, we illustrate that human telomerase reverse transcriptase (hTERT) promoter-induced CXCR4 knockdown inhibits PCa bone metastasis. We first investigated CXCR4 expressions and interactions of CXCR4/SDF-1 in PCa cells, developed a retrovirus system that could stably express CXCR4 small hairpin RNA driven by hTERT promoter and then determined the inhibitory effects of cell-specific blockade of CXCR4/SDF-1 pathway on PCa metastasis. It was shown that both PCa tissues and cell lines expressed CXCR4 and the expression in PCa tissue had a positive correlation to clinical stages while not to Gleason scores or serum PSA level. PCa metastases most presenting human tissues expressed high levels of SDF-1. Exogenous SDF-1 enhanced in vitro adhesion, migration and invasion of PCa cells and these bioeffects were repressed by hTERT promoter-induced CXCR4-shRNA expression. This CXCR4 knockdown was also found to significantly inhibit bone metastasis in vivo. We conclude that CXCR4/SDF-1 pathway plays an important role in PCa bone metastasis. hTERT promoter-induced tumor cell-specific CXCR4 gene silencing may prevent in vitro invasiveness and in vivo bone metastasis of PCa. These findings may enable new avenues of prevention and treatment for PCa metastasis.