Increased expression of connective tissue growth factor in patients with urethral stricture

Urethral stricture (US) is a urologic disorder with a high morbidity and recurrence rate, and may arise due to external trauma, surgical procedures or urethritis. The pathogenesis of US is closely associated with scar formation, including excessive collagen-rich connective tissues. Previous studies have shown that connective tissue growth factor (CTGF) plays a key role in the fibrosis process of many tissues and organs, such as kidney and lung. We investigated the variation of CTGF expression in urethral tissues from 12 patients with US and normal urethral tissues. The stricture length range was 1 to 2.5 cm, and 4 patients underwent repeated urethral dilatation. The normal urethral tissues were obtained from 6 patients with heart disease, who were suffering from brain death. The expression of CTGF mRNA and protein was analyzed by real-time PCR, immunohistochemistry, and western blotting analyses. Results showed that the expression level of CTGF mRNA was significantly increased in US patients compared with the control. In addition, US patients who have longer history and more repeated surgical procedures have extremely high CTGF mRNA levels and its protein expression, while the age of patients, position of injury and stricture length were not found obvious relation with CTGF expression. Moreover, the degree of collagen deposition and muscle fiber proliferation in the submucosa is consistent with the increase in CTGF expression. In conclusion, our data suggest that the up-regulation of CTGF expression may be responsible for the fibrosis process of urethral tissues in US patients.