association between p-glycoprotein and multi-drug resistance associated protein 1 expression and clinical outcomes in iranian retinoblastoma

purpose: the aim of the present study was to detect the expression of p-glycoprotein (p-gp) and multi-drug resistance associated protein 1 (mrp1) in retinoblastoma tumors, and analyze the relationship between its expression, the clinico-pathological features and recurrence. methods: p-gp and mrp1 expression in formalin-fixed paraffin-embedded retinoblastoma bearing ocular tissue sections from 26 patients were studied by immunohistochemistry assay, and the results were analyzed in correlation with clinico-pathological parameters. patients were classified into two groups according to their treatment: with (n=16) and without (n=10) preoperative chemotherapy. results: six (23%) and 12 (46%) tumors were p-gp and mrp1 positive respectively. three out of five tumors that presented p-gp had tumor invasion while mrp1 was positive in four tumors with invasion. seven patients showed recurrence during follow-up time that p-gp and mrp1 were expressed in three and four of them, respectively. there was no correlation between protein expression and clinical outcomes as recurrence in this study. conclusion: mrp1 and p-gp were intrinsically expressed in our study population. however, the results did not demonstrate significant association between p-gp and/or mrp1 positive expression and unresponsiveness to chemotherapy in iranian retinoblastoma patients.   iranian journal of ophthalmology 201426(1):17-22 © 2014 by the iranian society of ophthalmology