FER tyrosine kinase (FER) has been demonstrated to play a critical role in
tumorigenesis and
metastasis; however, its potential value as a novel prognostic marker for
clear cell renal cell carcinoma (ccRCC) remains unclear. In 48 paired samples of ccRCCs and normal adjacent tissues (ADTs), real-time PCR was used to evaluate the expression of FER
mRNA. The expression of
FER protein was assessed in 87 ADTs and 206 samples of ccRCC using immunohistochemical methods. Statistical analysis was used to examine the correlations between the expression levels of FER and the clinical characteristics of ccRCC patients. A significant difference was identified between ccRCC tissues and ADTs in the
mRNA levels of FER. Immunohistochemistry analyses revealed higher expression of
FER protein in 87 ccRCC samples compared to the paired ADTs. In addition,
FER protein expression in 206 ccRCC samples was significantly correlated with
tumor size, T stage, N classification,
metastasis, recurrence and Fuhrman grade, while associations with age and gender were not identifed. The Kaplan-Meier survival analysis showed that patients with high FER levels had a poorer survival outcome compared with those with lower levels. The log-rank test demonstrated that the cumulative survival rates were significantly different between the two groups. The Cox regression analysis indicated that FER expression, N stage and distant
metastasis were independent prognostic factors for overall survival of ccRCC patients. Our results indicate that overexpression of FER in
tumor tissues predicts a poor prognosis of patients with ccRCC, and FER may serve as a novel prognostic marker for ccRCC.