Inhibition of chemokine receptor CXCR4 as a novel therapeutic strategy in a prostate cancer xenograft model

Abstract

[한글]

[영문]

Purpose: The stromal derived factor-1 (SDF-1)/CXCR4 axis is associated with tumor aggressiveness and metastasis in prostate cancer. In this study, we explored whether a CXCR4-specific antagonist can abrogate the function of the SDF-1/CXCR4 axis and its downstream signaling. In addition, we tested the potential therapeutic effect of the CXCR4 antagonist in a prostate cancer xenograft model.Materials and methods: A representative metastatic prostate cancer cell line, PC-3 was used for in vitro and in vivo experiments. First, we tested the effect of SDF-1 and the CXCR4-specific antagonist, AMD3100, on PC-3 cell proliferation using a proliferation assay. Second, we evaluated whether AMD3100 could influence SDF-1 induced cell migration and SDF-1/CXCR4-mediated Akt signaling in PC-3 cells by migration assay and western blot. Finally, we investigated the effect of AMD3100 on tumor growth in a PC-3 tumor xenograft model by performing H&E staining and immunohistochemical staining of bcl-2, Ki-67 and CD34 to identify the histological differences between AMD3100-treated and untreated groups.Results: We found expression of CXCR4 protein in PC-3 cells. Cell proliferation was not significantly affected by SDF-1 (50 - 200 ng/ml) or AMD3100 (0.01 - 10 μg/ml) treatment. Further, the SDF-1/CXCR4 axis plays an important role in chemotactic migration in PC-3 cells, and AMD3100-treatment resulted in a 39.1 % reduction in SDF-1-induced migration. Western blot revealed that SDF-1 stimulation could enhance the expression of phosphorylated Akt in PC-3 cells, but the SDF-1-induced expression of phosphorylated Akt was abrogated in AMD3100-treated PC-3 cells. In the PC-3 tumor xenograft model, AMD3100 significantly inhibited tumor growth in nude mice inoculated with PC-3 cells, and AMD3100-treated PC-3 tumors had less microvessel formation and less immunoreactivity for the proliferation marker Ki-67 and the anti-apoptotic marker bcl-2 when compared to control tumors in vivo.Conclusions: The SDF-1/CXCR4 axis plays an important role in chemotactic migration and Akt signal pathway in PC-3 cells. The CXCR4-specific antagonist, AMD3100, effectively inhibits SDF-1-induced PC-3 cell migration and CXCR4/Akt signal transduction. Moreover, AMD3100 suppresses tumor growth in nude mice inoculated with PC-3 cells. We suggest that CXCR4 targeting might represent a novel strategy with potential utility for the treatment of human prostate cancer.