The contrasting roles of Dysferlin during tumor progression in renal cell carcinoma.

BACKGROUND: The vesicle fusion protein Dysferlin (DYSF) is mainly known as a membrane repair protein in muscle cells. Mutations of DYSF lead to muscular dystrophies and cardiomyopathies. In contrast to other members of the Ferlin protein family, few is known about its role in cancer. Our study was designed to investigate the expression and functional properties of DYSF in ccRCC and its association with clinicopathological parameters and survival. MATERIAL AND METHODS: TCGA cohort: mRNA expression data of DYSF were extracted from TCGA for patients with ccRCC (n = 603; ccRCC n = 522, benign n = 81). Study cohort: mRNA expression of DYSF in ccRCC was determined using qPCR (n = 126; ccRCC n = 82, benign n = 44). Immunohistochemical staining against DYSF was performed on tissue microarrays to validate protein expression (n = 172; ccRCC n = 142, benign n = 30). Correlations between mRNA/protein expression and clinicopathological data were statistically tested. Following siRNA-mediated knockdown of DYSF in ccRCC cell line ACHN, cell migration, invasion and proliferation were investigated. RESULTS: Both DYSF mRNA and protein expression are significantly up-regulated in ccRCC tissue. DYSF mRNA expression decreased during tumor progression: lower expression levels were measured in higher stage/grade and metastatic ccRCC with independent prognostic significance for overall and cancer-specific survival. In contrast, protein expression correlated positively with pathological parameters. Overexpression showed tendency toward poor survival. Accordingly, knockdown of DYSF suppressed migration and invasion of ccRCC cells. CONCLUSION: DYSF mRNA and protein expression are opposingly involved in tumor progression of ccRCC. DYSF could be used as a prognostic biomarker to predict survival of patients with ccRCC.