Comprehensive analysis of the expression and prognosis value of claudin family members in clear cell renal cell carcinoma

Objective: Clear cell renal cell carcinoma (ccRCC) accounts for 80% of all renal cancers and has a poor prognosis. Studies have found that the abnormal expression of claudins (CLNDs) can influence the functions of tight junctions (TJs) and plays an important role in the occurrence, development, and metastasis of malignant tumours in a variety of epithelial malignant tumours. However, the roles of the different CLNDs in ccRCC are poorly understood. Methods: Used the GEPIA, UALCAN, HPA, Kaplan-Meier Plotter, cBioPortal, String-DB, GeneMANIA, Metascape, and TIMER databases to collect data. Results: The expression levels of CLDN7, 8, 10, 11, 14, 16, and 19 were significantly reduced and promoters were hypermethylated in ccRCC-affected tissues. ccRCC patients with low expression levels are associated highly with the clinical cancer stages, tumour grades, and poor overall survival. Protein interaction and enrichment analysis showed the differential expressions of CLDNs were primarily associated with epithelial cell differentiation and regulation of cell adhesion. Moreover, differential expressions of CLDNs were significantly correlated with the infiltration of diverse immune cells, including six types of CD4+ T cells, macrophages, neutrophils, B cells, CD8+ T cells, and dendritic cells in ccRCC. Conclusion: They are expected to serve as biomarkers for predicting the prognosis of ccRCC patients.