pS6 Expression in Normal Renal Parenchyma, Primary Renal Cell Carcinomas and their Metastases

In cancer therapy novel concepts focus on phosphoinositide-3-kinase/protein kinase B/mammalian target of rapamycin (mTOR) inhibitors. In this context, phosphorylated S6 protein of the 40S ribosomal subunit (pS6) overexpression was previously shown to be associated with sensitivity to inhibitors of mTOR. The present study therefore evaluated pS6 expression in normal renal parenchyma (NRP), primary renal cell carcinomas (PRCC) and their metastases. pS6 and pmTOR expression was immunohistochemically analyzed in a tissue microarray (TMA) from localized primary renal cell carcinoma (lPRCC) ( n = 35), metastasized primary renal cell carcinoma (mPRCC) ( n = 45), their metastases ( n = 45), and NRP ( n = 45). pS6 expression was stronger in mPRCCs and metastases than in NRP and lPRCCs ( p