Association between P-glycoprotein and Multi Drug Resistance Associated Protein 1 Expression and Clinical Outcomes in Iranian Retinoblastoma

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 clinicopathological features and recurrence. P-gp and MRP1 expression in formalin-fixed paraffin-embedded tissue sections from 26 patients were studied by immunohistochemistry assay, and the results were analyzed in correlation with clinicopathological parameters. Patients were classified into two groups according to their treatment: with (n=16) and without preoperative chemotherapy (n=10). 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. MRP1 and multi drug resistance 1 (MDR1) were intrinsically expressed in our studied 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.