Cyclooxygenase-2 Overexpression in Chronic Inflammation Associated with Benign Prostatic Hyperplasia: Is It Related to Apoptosis and Angiogenesis of Prostate Cancer?

PURPOSE: This study was performed to investigate the relationship between cyclooxygenase-2 (COX-2) expression and apoptosis/angiogenesis in inflammatory and noninflammatory benign prostatic hyperplasia (BPH) and prostate cancer (PC). MATERIALS AND METHODS: This study involved 64 BPH and 57 PC patients. The BPH histopathologies were classified by the presence of chronic inflammation as follows: noninflammatory BPH (NI-BPH; n=23) and inflammatory BPH (I-BPH; n=41). The association between the expression of COX-2, expression of Bcl-2, the apoptotic index (AI), expression of vascular endothelial growth factor (VEGF), and microvascular density (MVD) in the prostate was investigated. RESULTS: An overexpression of COX-2, Bcl-2, and VEGF was observed in cases of PC compared with cases of BPH. In PC, the AI was lower and MVD was higher than in BPH. In NI-BPH, I-BPH, and PC, the overexpression of COX-2, Bcl-2, and VEGF gradually increased. The AI was high in I-BPH, but did not differ significantly between the NI-BPH and I-BPH groups or between the NI-BPH and PC groups. MVD was significantly high in PC, but no significant difference was found between NI-BPH and I-BPH. A significant correlation was shown between the overexpression of COX-2 and Bcl-2, and COX-2 and VEGF. However, the AI was not correlated with the overexpression of COX-2 or Bcl-2. MVD was correlated with the overexpression of COX-2 and VEGF. CONCLUSIONS: COX-2 overexpression in PC is correlated with a decrease in apoptosis and an increase in angiogenesis. Chronic inflammation in BPH causes an overexpression of COX-2, which induces the increased expression of Bcl-2 and VEGF. It is likely that chronic inflammation plays a role in the intermediate step of carcinogenesis in the prostate.