Spock1 expression predicts prognosis in prostate cancer

Purpose: Prostate cancer is a common cancer and it can often be treated successfully. The 15-year survival rate is more than 90% in patients with early stage, However, once the tumor metastasis occurred, the prognosis got significantly worse. Therefore, to identify patients with malignant potential while diagnosing might improve clinical outcome. The aim of this study was to evaluate the expression of SPOCK1 (sparc/osteonectin, cwcv and kazal-like domains proteoglycan (testican) 1) and its clinical significance in prostate cancer.

Materials and Methods: SPOCK1 expression was measured by immunohistochemical staining of samples from 71 patients with prostate cancer. The correlation between SPOCK1 expression and clinicopathological features was quantitatively analyzed. The prognostic value of SPOCK1 for overall survival was determined by Kaplan-Meier analysis and Cox proportional hazard models. For underlying molecular mechanism, prostate cancer cell lines were used and SPOCK1 expression was knock-down via siRNA. Migration and invasion assay were performed to determined the tumor malignancy. The downstream signaling pathway will be analyzed with real-time RT-PCR and western blot.

Results: Seventy-one patients with mean age of 74.4 years (range 59 to 97 years) were included. Clinicopathological features, including histological type, differentiation, lymph node metastasis, TNM stage, and tumor size were assessed. Patients with high SPOCK1 expression were more prone to be advanced stage. As to the prognosis, the median follow-up for overall survival was 5.2 ± 2.9 years (range: 0.7 to 11.8 years). Moreover, a high POCK1 expression level was correlated with poor survival. The underlying mechanism is under investigation.

Conclusion: Our results suggest that SPOCK1 expression is enhanced in prostate cancer. High SPOCK1 expression, either alone or in combination with other pathologic staging factors, may therefore serve as a poor prognostic marker for prostate cancer.