Profilin 1 overexpression in renal cell carcinoma

Objectives: To gain information about overexpressed antigens in renal cell carcinoma (RCC) by using a chemical proteomics approach. Methods: RCC cell line 769P was cultured and proteome analysis was subsequently carried out in the culture supernatants. By using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and tandem mass spectrometry (LC-MS/MS), proteins in the culture supernatants were searched. A MEDLINE search to define the functions of the identified proteins was carried out. Results: Four differentially regulated proteins (profilin 1, amyloid beta A4 protein [APP], proprotein convertase subtilisin/kexin type 1 inhibitor [ProSAAS], galectin-3-binding protein [LGALS3BP]) were selected. These were not overexpressed in normal kidney tissue or reported in RCC. Their levels were measured through western blotting of normal kidney and RCC tissues. No differences were observed in the expression levels of APP, ProSAAS or LGALS3BP between RCC and normal kidney tissues. Profilin 1 was overexpressed in RCC tissue. On the basis of this observation, an immunohistochemical analysis of profilin 1 in normal kidney and RCC tissues was carried out. In normal tissues, tubules that were sources of RCC stained positive for profilin 1. In RCC tissue, in contrast, the stromal cells in the tumors stained positive. Conclusions: Profilin 1 can be a key element in the pathological processes of RCC, such as tumorigenesis and/or tumor growth. Thus, it has the potential to serve as a diagnostic or progression biomarker and therapeutic target in RCC.