Background: The progression of solid tumors is at least partly dependent on angiogenesis, the induction of which is mediated by several angiogenic factors, including angiogenin (ANG). The authors evaluated the expression of ANG in the tumor tissue and serum of patients with urothelial carcinoma.
Methods: The expression of ANG in 5 human bladder carcinoma cell lines and 24 urothelial carcinomas (10 superficial carcinomas and 14 invasive carcinomas) and in corresponding normal urothelial tissues was investigated by reverse transcriptase-polymerase chain reaction and Northern blot analysis. Serum levels of ANG in 52 healthy volunteers and in 135 patients with urothelial carcinomas (81 superficial carcinomas and 54 invasive carcinomas) were measured by using a sandwich enzyme immunoassay.
Results: ANG mRNA transcripts were detected in all of the bladder carcinoma cell lines, urothelial carcinomas, and normal tissues. The mean level of ANG expression in invasive urothelial carcinomas was 4-fold higher than in superficial carcinomas and 5-fold higher than in normal tissues. The mean serum ANG concentration for invasive urothelial carcinoma patients (514.6+/-211.1 ng/mL) was significantly higher than for superficial urothelial carcinoma patients (381.7+/-169.3 ng/mL) and healthy volunteers (337.5+/-71.4 ng/mL). The overall survival rate of patients with elevated serum levels of ANG was significantly lower than that of patients with normal levels. Moreover, among the 47 patients with advanced urothelial carcinoma who underwent complete resection, the disease free survival rate of patients with elevated serum levels of ANG was significantly lower than that of patients with normal levels.
Conclusions: These results indicate that ANG is strongly expressed in the tumor tissue and is present in high levels in the serum of patients with invasive urothelial carcinoma compared with superficial carcinoma patients and that elevation of serum ANG level could be used as a novel predictor of the prognoses of patients with urothelial carcinoma.