OBJECTIVETo investigate the action mechanisms of the FZD5 gene in prostate cancer bone metastasis and search for some new treatments for this disease.

METHODSWe determined the expression level of the FZD5 gene in prostate cancer PC3 cells and, after transfection of siRNA into the PC3 cells and silence of the FZD5 gene, observed the changes in the migration and proliferation of the cells. We established the model of prostate cancer bone metastasis by tibial injection of prostate cancer cells in the nude mice. Then we injected control siRNA and FZD5-silenced siRNA into the tibia of the mice followed by evaluation of tumor-induced bone destruction by X-ray imaging at 0, 1, and 3 weeks and by HE staining at 3 weeks after injection.

RESULTSAfter transfection of FZD5-silenced siRNA into the prostate cancer PC3 cells, the expression of the FZD5 gene was decreased about 70%. The rate of cell proliferation was significantly lower in the gene silencing group than in the control (P < 0.05), and that of cell migration dropped by 30% in the former as compared with the latter group at 48 hours after FZD5 silencing (P < 0.05). At 3 weeks after injection of control siRNA or FZD5-silenced siRNA into the tibia of the mice, osteolytic damage was observed in both groups, though less in the FZD5 silencing group, with only a few remaining bone trabeculae visible.

CONCLUSIONSilencing the FZD5 gene can reduce the migration and proliferation of prostate cancer cells, help to suppress bone metastasis and destruction, and thereby improve the survival rate and quality of life of the patients.