[Expression of lung resistance-related protein gene in transitional cell carcinoma of the bladder].

ABSTRACT

OBJECTIVE: To investigate the role of lung resistance-related protein (LRP) in intrinsic multidrug resistance (MDR) of bladder cancer and detect the relationship of LRP expression with the clinical pathologic parameters. METHODS: 66 patients were studied with newly diagnosed primary bladder cancer (T(a) = 12, T(1) = 26, T(2) = 11, T(3) = 10, T(4) = 7; G(1) = 35, G(2) = 19, G(3) = 12). No patient was treated preoperatively with either radiation or chemotherapy. Reverse transcription-polymerase chain reaction (RT-PCR) was performed for measure of mRNA expression for LRP, multidrug-resistance gene 1 (MDR1), and multidrug resist nce-associated protein 1 (MRP1). Expressions of LRP, P53 and P63 proteins were examined by immunohistochemistry staining. RESULTS: LRP mRNA had the highest expression rate (64%, 42/66) among three MDR markers in primary bladder cancers without chemotherapy and its level was significantly higher in normal bladder tissue than in TCC of bladder (t = 2.82, P < 0.01), in low grade than in high grade cancers (t = 4.14, P < 0.01), and in superficial than in invasive cancers (t = 3.58, P < 0.05). LRP mRNA expression showed no correlation with either MDR1 or MRP1, but close correlation with LRP protein level (r = 0.89, P < 0.01). LRP was associated with low-grade (r = 0.81, P < 0.01) and low-stage (r = 0.78, P < 0.05) cancers, but not with tumor suppressor P53 or P63 (P > 0.05). CONCLUSIONS: The grade and stage-related expression pattern of LRP indicates that it may be a predictive index for intrinsic MDR in bladder cancer. Anti-cancer drugs out of the MDR spectrum of LRP may be more effective for patients with early bladder cancer.