Abstract
OBJECTIVE: To study the expression levels of the NOK (novel oncogene with kinase-domain) gene in renal cell carcinoma (RCC) and its association with the progression of this cancer. METHODS: In this study, immunohistochemistry (IHC) and Western blot analyses were applied to investigate the NOK expression level in RCC and adjacent normal renal tissue samples. MTT, colony formation, and migration assays were also utilized to evaluate the role of NOK in RCC cell lines. RESULTS: Knocked-down expression of NOK in an RCC cell line (786-O) suppressed cellular proliferation and migration by restraining the activation of AKT and ERK. We found that the expression level of NOK was significantly higher in RCC tissues than in their adjacent tissues, and more importantly, overexpression of NOK was evidently correlated with the tumor TNM stage and Fuhrman grade (P<0.001). A high level of NOK was also associated with poor overall survival (P<0.05) and disease-free survival (P<0.05) by Kaplan-Meier analysis. CONCLUSIONS: NOK expression increased in RCC and was significantly correlated with TNM stage, Fuhrman grade, poor overall survival, poor disease-free survival, metastasis, and proliferation in RCC cells by regulating the activation of AKT and ERK, suggesting that NOK may play important roles as a positive regulator to RCC.