INVESTIGATIVE UROLOGY

Expression of COX-2 in Normal and Pyelonephritic Kidney, Renal Intraepithelial Neoplasia, and Renal Cell Carcinoma
Mungan MU, Gurel D, Canda AE, Tuna B, Yorukoglu K, Kirkali Z
Dokuz Eylul University School of Medicine, Department of Urology, Izmir, Turkey
Eur Urol. 2006; 50: 92-7; discussion 97

• Objectives: The role of inflammation in carcinogenesis is unknown. To determine the relationship between cyclooxygenase 2 (COX-2) expression, inflammation, and carcinogenesis in human renal cell carcinoma (RCC), we looked for COX-2 expression in normal and pyelonephritic kidney, renal intratubular neoplasia (RIN), and RCC tissues.
• Methods: COX-2 expression was assessed immunohistochemically in tissues obtained from 20 pyelonephritic kidneys, 16 normal kidneys, 19 RIN, and 75 RCC cases.
• Results: COX-2 expression was found to be positive in 64% of RCCs. It was positive in 13 chronic pyelonephritic (65%), 9 normal (56%), and 15 RIN (79%) cases. COX-2 expression was significantly higher in RCC and RIN than the normal and pyelonephritic cases (p < 0.001 and p < 0.001, respectively). No statistically significant difference was noted between RCC and RIN cases.
• Conclusions: Although the function of COX-2 in tumor development has not been exactly elucidated, the increased expression of COX-2 in RIN and RCC might be a factor that may play a role in the development of RIN or progression to RCC, which warrants further research.
  
  
• Editorial Comment
  Results of previous studies support the importance of neovascularity in tumor growth and that cyclooxygenase 2 expression may be an important regulator of neovascularity in renal cell carcinoma. The authors of this study found that there is no significant difference between cyclooxygenase 2 expression in normal and pyelonephritic kidney tissues. It is indicative of differences in the mechanism of inflammation in pyelonephritis (infectious agents) and peritumoral inflammation occurring around the tumor due to anti-tumor immune response, which could induce cyclooxygenase 2 expression. The authors pointed out that the peritumoral kidney tissue inflammation seems to have different molecular characteristics than inflammated kidney tissue in pyelonephritis, such as increased cyclooxygenase 2 expression. Although preclinical and in the experimental setting, this paper opens new avenue in the treatment of renal cell carcinoma, that is the use of cyclooxygenase 2 inhibitors.

Dr. Francisco Sampaio
Full-Professor and Chair, Urogenital Research Unit
State University of Rio de Janeiro
Rio de Janeiro, Brazil