Expression and association of carbonic anhydrase IX and cyclooxygenase-2 in colorectal cancer.

Background: This work was designed to determine the relationship between hypoxia-inducible protein carbonic anhydrase IX (CA IX) and pro-inflammatory enzyme cyclooxygenase-2 (COX-2) in patients with colorectal cancer (CRC).

Methods: We examined CA IX and COX-2 expression in CRC tissues by immunohistochemical staining of 111 samples. We evaluated the correlation between the expression of these proteins and their correlation with the clinico-morphological parameters of CRC.

Results: CA IX was detected in 89 of 111 cases (80.2%). We predominantly observed membrane staining (70.3%) and a strong immunoreaction intensity (58.6%). The percentage of labeled cells in malignant lesions was less than 25% in 12.6% of cases, less than 50% in 15.3% of cases and more than 50% in 52.3% of CRC cases. The COX-2 protein was expressed in 94 of 111 cases (84.7%). We noticed only cytoplasmic localization, while immunoreaction intensity was predominantly strong (47.8%). The percentage of COX-2 positive cells was less than 25% only in 2.7% of the cases, less than 50% in 21.6% of the cases and more than 50% in 60.4% of the cases. No statistically significant correlations were observed between CA IX expression and clinico-morphological parameters. COX-2 expression was only significantly correlated with the tumor stage. Statistical analysis confirmed a significant correlation between the parameters of expression of the CA IX and COX-2 proteins.

Conclusion: CA IX/COX-2 interplay can promote hypoxia survival and the invasion of tumor cells. These proteins may represent independent prognostic factors of CRC.