Cyclooxygenase-2 Expression in Retinoblastoma: An Immunohistochemical Analysis

Abstract

Purpose: Increased level of cyclooxygenase-2 (COX-2) plays a significant role in the pathogenesis of cancers. High expression of COX-2 has been demonstrated in several cancer types including retinoblastoma. However, the in vivo study did not confirm the anti-proliferative effect of COX-2 inhibitor, celecoxib, on a murine transgenic retinoblastoma model. We, therefore, aim to investigate COX-2 expression in paraffin-embedded retinoblastoma specimens in a larger study group.

Methods: We reviewed 55 retinoblastoma specimens obtained during 1995 to 2005. Clinical and histopathological data were recorded. Immunohistochemical evaluation of COX-2 expression was performed using a rabbit monoclonal antibody to human cyclooxygenase-2. Results: Forty-four of 55 specimens (80%) showed negative immunoreactivity for COX-2 expression. For the 11 specimens (20%, 95% CI = 11.6–32.4%) with positive COX-2, all immunostainings were less than 50% of tumor area. Demographic data and treatment details were available in 53 specimens. Enucleation was performed as a primary treatment in 43 specimens (81%). Other treatments, mainly systemic chemotherapy, were given prior to enucleation in 10 specimens (19%). There was no statistical difference in COX-2 expression between the specimens identified as primary and secondary enucleation (p = 0.66). Regarding the histopathological findings, there were no significant differences between COX-2 negative and COX-2 positive groups.

Conclusions: It appears that COX-2 is not overexpressed in our retinoblastoma specimens, which is different from previous studies. This conflicting data reduces the possibility of introducing Cox-2 inhibitors in the treatment of retinoblastoma.

KEYWORDS::

• Angiogenesis
• Cyclooxygenase-2
• Immunohistochemical analysis
• Monoclonal antibody
• Retinoblastoma

ACKNOWLEDGMENTS

The authors would like to acknowledge financial support from a Siriraj grant for Research Development and Medical Education. They would also like to thank Mr. Suthipol Udompunthurak for his valuable advice on the statistical analysis. The study was supported by Siriraj Grant for Research Development and Medical Education.

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.