Pax6 Expression In Retinoblastoma

Abstract

Purpose: : Retinoblastoma (RB) is the most common malignant intraocular tumour in childhood and the most common tumour of the retina. PAX6 is a transcription factor involved in a vast number of cellular processes, including the regulation of eye development. Its expression has also been studied in various types of cancers. The aim of this experiment is to study the expression of PAX6 in RB and its correlation with histopathological prognostic factors.

Methods: : Cases of RB were retrieved from the pathology archives of our institution, as well as normal adult and fetus eyes. All specimens were immunostained with PAX6 in a fully automated process. The expression was analyzed according to the intensity and percentage of tumour cells positively stained. The scores obtained were correlated with histopathological features (optic nerve, anterior chamber and choroid invasion, tumour differentiation, necrosis, and vitreous seeding).

Results: : Forty-five formalin-fixed paraffin-embedded retinoblastoma as well as 5 normal adult eyes and 2 fetal eyes were examined. The grading was distributed as follows: 1 tumor with a total score of 0 (totally necrotic tumour, excluded from the statistical analysis); none with a total score of 1; 7 with a total score of 2; 4 with a total score of 3; 5 with a total score of 4; 9 with a total score of 5; and 19 with the highest score possible, 6. No statistical correlation was found between the staining and any of the histopathological prognostic factors. The retina was positive in all 5 normal eyes and in the 2 fetal eyes.

Conclusions: : Although it is clear that PAX6 is expressed in retinoblastoma, its role in the development and progression of the tumour needs to be studied. Future research should focus on determining through which pathways PAX6 acts in retinoblastoma, and how or if its expression truly does promote the growth of the tumour. If this is indeed the case, PAX6 could potentially be used as a drug target for the treatment of retinoblastoma.

Keywords: retinoblastoma • immunohistochemistry • transcription factors