Background. Renal cell carcinomas (RCC) respond poorly to anthracyclines, Vinca alkaloids, and other agents. P‐glycoprotein is overproduced in multidrug‐resistant cells and thought to function as an energy‐dependent drug efflux pump. The authors thus examined the expression level of P‐glycoprotein in RCC and transitional cell carcinomas (TCC). Methods. P‐glycoprotein was detected using immunoblotting with a monoclonal antibody against it, C219. Results. Thirty‐three of 38 patients with RCC and 3 of 17 patients with TCC had P‐glycoprotein positive tumors. The expression level of P‐glycoprotein in most of RCC was lower than that in the normal kidney tissues and that of P‐glycoprotein in the TCC was very low. The size of P‐glycoprotein in 14 RCC and 3 TCC was 5–10 kilodaltons smaller than in the normal renal tissues. The variation of P‐glycoprotein size in the RCC was attributed to differential N‐linked glycosylation. P‐glycoprotein in a RCC was photolabeled by tritiated azidopine, and the labeling was inhibited by some organic agents. P‐glycoprotein distributed on the apical or marginal cell surface of the RCC. Conclusions. These data show that P‐glycoprotein was expressed in many RCC, and its expression level, glycosylation, and distribution were altered. These data also suggest that the P‐glycoprotein in RCC had similar drug binding site(s) to that in multidrug‐resistant cells.
|出版ステータス||Published - 1993 6月 1|
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