Expression of lung resistance-related protein in transitional cell carcinoma of bladder

Abstract

Objectives To determine the role of lung resistance-related protein (LRP) in intrinsic multidrug-resistance (MDR) of bladder cancer. Methods The study group consisted of 66 patients with newly diagnosed primary bladder cancer. No patient had been treated preoperatively with either radiotherapy or chemotherapy. Reverse transcriptase-polymerase chain reaction was performed to measure LRP, multidrug resistance-associated protein 1 (MDR1), and MRP1 mRNA expression. The expression of LRP, p53 proteins, and p63 proteins was examined by immunohistochemistry. We analyzed the correlation of LRP with the above indexes and the clinical pathologic parameters. Results The expression rate of LRP mRNA (63.6%) was the greatest among the three MDR markers in primary bladder cancer without exposure to chemotherapy. The LRP mRNA level was significantly greater in normal bladder tissue than in transitional cell carcinoma bladder tissue ( P <0.01) and in superficial cancer than in invasive cancer ( P = 0.013). LRP mRNA expression showed no association with either MDR1 or MRP1, but close correlation with the LRP level ( P = 0.001). LRP was associated with low-grade ( P <0.01) and low-stage ( P <0.05) cancer but had no association with tumor suppressor p53 or p63. Conclusions The grade and stage-related expression pattern of LRP indicates that it may be a predictive index for intrinsic MDR in early bladder cancer. Anticancer drugs out of the MDR spectrum of LRP may be more effective for patients with early bladder cancer.