PTEN expression in renal cell carcinoma and oncocytoma and prognosis.

AIMS Deletion or inactivation of the tumour suppressor gene PTEN (phosphatase and tensin homologue deleted from chromosome 10) contributes to tumorigenesis in a variety of human carcinomas. The present study evaluated PTEN expression in renal cell carcinomas and oncocytomas. METHODS A tissue microarray from 493 specimens including renal cell carcinomas (n = 440), oncocytomas (n = 21) and tumour-negative renal tissue (n = 32) from patients (n = 461) was incubated with an anti-PTEN antibody for subsequent analysis of PTEN expression. Furthermore, the effect of PTEN expression on the survival of renal carcinoma patients was evaluated. RESULTS Renal cell carcinomas, and even more pronouncedly oncocytomas, expressed PTEN predominantly in the cytoplasm. In contrast to oncocytomas, PTEN expression was typically decreased in renal cell carcinoma subtypes. PTEN expression in sarcomatoid renal cell carcinomas was comparable to that in non-sarcomatoid subtypes. The PTEN expression pattern had no significant influence on prognosis. CONCLUSIONS Renal tumours (renal cell carcinomas and oncocytomas) express PTEN protein predominantly in the cytoplasm. A reduction in PTEN expression appears to be an early step in renal cell carcinogenesis. However, the PTEN expression pattern of renal cell carcinomas apparently is not prognostic for patient survival.