Expression of signal transducer and activator of transcription 3 and suppressor of cytokine signaling 3 in urothelial carcinoma.

In this study, we investigated the expression of phosphorylated signal transducer and activator of transcription 3 (p-STAT3) Tyr705 and suppressor of cytokine signaling 3 (SOCS3) in urothelial carcinoma (UC). p-STAT3 (Tyr705) and SOCS3 were analyzed by immunohistochemistry using tissue microarray and Western blotting. Our results showed that p-STAT3 (Tyr705) was frequently detected in high-grade and infiltrating UC. However, there was no difference in p-STAT3 (Tyr705) staining between UC of the upper and lower urinary tracts. In addition, there was no significant correlation between expression of SOCS3 and histological differentiation and invasiveness of UC. These findings suggest that overexpression of p-STAT3 (Tyr705) occurs in UC, and that pathways other than SOCS3 may contribute to its activation in this cancer.