Tumour necrosis factor receptor-associated factor-1 (TRAF-1) expression is increased in renal cell carcinoma patient serum but decreased in cancer tissue compared with normal: potential biomarker significance

Renal cell carcinoma (RCC) generally has a poor prognosis because of late diagnosis and metastasis. We have previously described decreased tumour necrosis factor receptor-associated factor-1 (TRAF-1) in RCC compared with paired normal kidney in a patient cohort in Australia. In the present study, TRAF-1 expression in clear cell RCC (ccRCC) and normal kidney was again compared, but in a cohort from University Malaya Medical Centre. Serum TRAF-1 was also evaluated in RCC and normal samples. Immunohistochemistry with automated batch staining and Aperio ImageScope morphometry was used to compare TRAF-1 in 61 ccRCC with paired normal kidney tissue. Serum from 15 newly diagnosed and untreated ccRCC and 15 healthy people was tested for TRAF-1 using ELISA. In this cohort, TRAF-1 was highly expressed in proximal tubular epithelium of normal kidney, and significantly decreased in ccRCC tissue (p < 0.001). Conversely, TRAF-1 in serum from ccRCC patients was significantly increased over control serum (132±30 versus 54±14 pg/mL, respectively; p=0.013). Decreased TRAF-1 in RCC tissue, reported previously, was confirmed. This, along with significantly increased serum TRAF-1 may indicate the protein is actively secreted during development and progression of ccRCC Therefore, the increased serum TRAF-1 may be a useful non-invasive indicator of RCC development.