Overexpression of cyclooxygenase-2 in urothelial carcinoma in conjunction with tumor-associated-macrophage infiltration, hypoxia-inducible factor-1alpha expression, and tumor angiogenesis

Abstract

This study examines whether the expression of cyclooxgenase-2 (COX-2) in urothelial carcinoma (UC) is associated with macrophage infiltration, hypoxia-inducible factor-1alpha (HIF-1alpha) expression and angiogenesis. We investigated the expression of COX-2 associated with HIF-1alpha and performed double immunohistochemical analysis of 216 UCs for COX-2 expression and the correlation with tumor-associated-macrophage (TAM) density and microvessel density (MVD) in situ. A high expression of COX-2 was positively correlated with tumor invasiveness, histologic grade and HIF-1alpha expression in UC (p<0.0001, p=0.003, p<0.0001, respectively). Quantification of double staining of COX-2/CD34 and COX-2/CD68 showed that a higher MVD and TAM density was found in COX-2 high-expression than in COX-2 low-expression tumor fields (p<0.0001). Adjacent to the principal of COX-2 expression areas, MVD value and TAM density were significantly increased in HIF-1alpha high-expression specimens compared with HIF-1alpha low-expression ones (p<0.0001). Interestingly, our data revealed that high COX-2 expression (p=0.002), high HIF-1alpha expression (p<0.0001) and TAM density (p<0.0001) were all associated with high MVD value. Our results suggest that COX-2 may produce a cooperative effect in promoting tumor progression and may be involved in the process of angiogenesis through increasing TAM infiltration or HIF-1alpha regulation by hypoxia.