High-level expression of periostin is significantly correlated with tumor angiogenesis in prostate cancer.

Periostin (PN), originally named osteoblast-specific factor-2 (OSF-2), is a multifunctional glycoprotein which can significantly promote EMT (epithelial-mesenchymal transition). Recently, many studies have shown that high-level expression of PN is correlated significantly with tumor angiogenesis and prognosis in many kinds of human cancer. In previous experiments, we screened PN from prostate cancer through iTRAQ technology and found that PN affects occurrence and development of prostate cancer (PCa). However, whether and how periostin expression influences tumor angiogenesis in prostate cancer remains unknown. Our study aimed to examine expression of PN in patients with PCa and explored the relationship of PN expression with clinicopathologic factors and tumor angiogenesis. Immunohistochemistry was performed to determine expression of PN in PCa and benign prostate hyperplasia (BPH). Vascular endothelial growth factor (VEGF) and CD31 (used to mark tumor angiogenesis) were also examined in tissues from the PCa patients and hyperplasia patients mentioned above. The results showed that PN expression was significantly (P<0.001) higher in PCa (58%) than in BPH (18.8%) and VEGF expression was significantly (P=0.003) higher in PCa (55%) than in BPH (24.5%). Increased PN protein expression was associated with Gleason score (P=0.005) but there was no correlation with age (P=0.548), PSA (P=0.343) or clinic tumor staging (P=0.049). The results also showed that high expression of PN correlated with VEGF expression (P<0.001) and that tumors with PN-positive expression had significantly higher microvessel density (38.7±14.4 vs. 29.7±10.5; P=0.026) compared to those with PN-negative. In conclusion, our findings suggest that PN may have an important role in tumor progression and may impact tumor angiogenesis in prostate cancer.