Syndecan-1 expression in locally invasive and metastatic prostate cancer

OBJECTIVES: To determine the significance of syndecan-1 expression, a cell-surface heparan sulfate proteoglycan in localized and metastatic prostate cancer.

METHODS: We performed a retrospective analysis of 76 men with Gleason sum 6 or 7 prostate cancer treated by radical prostatectomy and a separate cohort of 75 men with metastatic prostate cancer. Syndecan-1 immunoreactivity was measured in primary prostate specimens or in samples from metastatic sites and correlated with patient outcome.

RESULTS: Syndecan-1 was expressed in normal basal and secretory epithelial cells, 26% of radical prostatectomy specimens, and 35% of metastatic disease. No association was found between syndecan-1 positivity and prostate-specific antigen recurrence in the collective cohort of Gleason sum 6 and 7 cancers. However, when stratified by Gleason sum, syndecan-1 immunoreactivity (immunoreactivity score 150 or greater) was associated with a greater recurrence rate in Gleason sum 7 cancers. Expression of syndecan-1 was significantly greater in soft tissue than in bone metastasis (P = 0.048, Fisher's exact test).

CONCLUSIONS: Consistent with a possible biochemical role for syndecan-1 in prostate cancer progression and metastasis, syndecan-1 expression correlated with serologic recurrence in Gleason sum 7 prostate cancer and was highly expressed in soft-tissue metastases.