c-Met and EPHA7 Receptor Tyrosine Kinases Are Related to Prognosis in Clear Cell Renal Cell Carcinoma: Focusing on the Association with Myoferlin Expression

Abstract

Simple Summary Receptor tyrosine kinases are essential for the development, growth, and progression of clear cell renal cell carcinoma (ccRCC). Targeted therapies using receptor tyrosine kinase inhibitors are widely used in ccRCC treatment. Myoferlin is a well-known protein that regulates various receptor tyrosine kinases. We aimed to identify myoferlin-associated receptor tyrosine kinases and their prognostic implications in ccRCC. After screening with proteomic analysis, we focused on c-Met and EPHA7 receptor tyrosine kinases. c-Met expression was associated with poor prognosis in ccRCC, and there was an indication that the c-Met pathway may be regulated by myoferlin. Although the expression of EPHA7 and myoferlin was not corelated, the expression of EPHA7 was also associated with unfavorable outcomes. These results suggest that c-Met and EPHA7 might be useful prognostic biomarkers, and the presumed myoferlin/c-Met pathway could be a novel therapeutic target in ccRCC. Receptor tyrosine kinases (RTKs) are important targets for clear cell renal cell carcinoma (ccRCC) treatment. Myoferlin is a strong regulator of RTKs. To identify myoferlin-associated RTKs and their prognostic implications in ccRCC, we investigated the expression of RTKs and myoferlin using proteome-based evaluation and immunohistochemical staining in tissue microarray. Multivariate Cox analysis adjusted for TNM stage and WHO grade was performed (n = 410 and 506). Proteomic analysis suggested c-Met and EPHA7 as novel candidates for myoferlin-associated RTKs. We immunohistochemically validated the positive association between c-Met and myoferlin expression. High c-Met expression was independently associated with overall (hazard ratio (HR) = 1.153-2.919) and cancer-specific survival (HR = 1.150-3.389). The prognostic effect of high c-Met expression was also determined in an independent cohort (overall survival, HR = 1.503-3.771). Although expression of EPHA7 and myoferlin was not correlated, EPHA7 expression was independently associated with progression-free (HR = 1.237-4.319) and cancer-specific survival (HR = 1.214-4.558). In addition, network-based prioritization showed co-functional enrichment of c-Met and myoferlin, suggesting a novel regulatory function of myoferlin in c-Met signaling. This study indicates that c-Met and EPHA7 might be useful prognostic biomarkers, and the presumed myoferlin/c-Met pathway could be a novel therapeutic target in ccRCC.