OBJECTIVETo investigate the expression of cyclin-dependent kinase inhibitor p27kip1 in renal cell carcinoma and its clinical significance.

METHODSThe expressions of p27kip1 mRNA and protein were evaluated using reverse transcription polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry with tissue chip technique in renal cell carcinoma (RCC) tissues, adjacent tissues and 786-0 cell line. The relationship between the expression of p27kip1 and the tumor size, the clinical stage, pathological type and stage were evaluated, and the results by the 3 methods were analyzed to evaluate the relationship between the mRNA and protein of p27kip1.

RESULTSThe expression of p27kip1 protein (detected by immunohistochemistry and Western blotting) in RCC tissue was significantly lower than that in the adjacent normal tissues (P<0.05). The expression of p27kip1 mRNA (by RT-PCR) showed no significant difference between the two groups. p27kip1 protein expression was found to be inversely correlated to the tumor grade and clinical stage (P<0.05). Western blotting and immunohistochemistry showed a high coincidence rate in the detection of P27kip1 protein expression in RCC samples (P<0.001, K=0.828).

CONCLUSIONp27kip1 mRNA expression shows no difference between RCC and normal tissues, while the protein expression is significantly lower in the cancer tissues, suggesting a regulatory mechanism of p27kip1 expression at the transcriptional level. Low expression of p27kip1 protein may promote the development and progression of RCC. p27kip1 protein may serve as a diagnostic and prognostic marker of RCC.