The effect of a selective cyclooxygenase-2 (COX-2) inhibitor on the proliferation rate of retinoblastoma cell lines

Purpose: To examine the effect of nepafenac, a selective cyclooxygenase-2 (COX-2) inhibitor, on the proliferation rate of two human retinoblastoma (Rb)cell lines. Methods: Two human Rb cell lines (WERI-RB and Y79) were cultured. COX-2 expression in these cell lines was verified by imunocytochemical analysis of cytospin sections and Western blotting. An MTT-based proliferation assay was used to compare Rb cell growth with and without amfenac, the active metabolite of nepafenac. The averaged results per condition were recorded. The Student's t-test was used to compare results from the cells cultured with and without amfenac. Result: The Y79 cell line showed a higher proliferative rate than the WERI-RB cell line. Both cell lines were negative for COX-2 expression by immunocytochemical analysis; however, both cell lines were positive for COX-2 expression by Western blot. When amfenac was added to both of the cell lines, a statistically significant reduction in proliferation was observed in both cell lines. The two Rb cell lines were positive for COX-2 only in the Western blot, indicating that they probably express low levels of COX-2, which was undetectable by immucytochemical analysis. Conclusion: The selective, anti-COX-2 molecule amfenac inhibited proliferation of both tested Rb cell lines. Further trials should be undertaken to study the effect of selective COX-2 inhibitors on Rb.