Caspase 4 Overexpression in Clear Cell Renal Cell Carcinoma and Its Prognostic Role

Abstract Background: Caspase 4 (CASP4) dysregulation is related to the occurrence, development, and outcome of many malignant tumors, but its role in clear cell renal cell carcinoma (ccRCC) is unclear. This study was conducted to investigate the expression level of CASP4 in tumor tissues and its relationship with clinical prognosis of patients with ccRCC. Methods: First, the Oncomine and The Cancer Genome Atlas databases were used to determine CASP4 mRNA expression in ccRCC and its association with ccRCC prognosis. We then performed immunohistochemical staining and evaluation of 30 paired ccRCC and adjacent normal tissues to confirm these results. The correlation between CASP4 expression and ccRCC prognosis was evaluated using Kaplan-Meier analysis, and related genes and pathways were obtained from The Cancer Genome Atlas database by gene set enrichment analysis and gene set variation analysis. Finally, we explored the co-expression of genes with CASP4 in ccRCC. Results: CASP4 mRNA expression in ccRCC was significantly higher than that in normal tissues (p < 0.001). Kaplan-Meier analysis showed that the overall survival of patients with ccRCC showing high CASP4 expression was significantly reduced (p < 0.001). We then used external datasets (Gene Expression Omnibus database and patients from our center) to verify the level of CASP4 expression and survival differences (all p < 0.05). We also found that differential expression levels of CASP4 were correlated with pathological grade and clinical TNM stage (all p < 0.05). Conclusions: Overall, our study shows that CASP4 is highly expressed in ccRCC and is an important factor affecting prognosis. Thus, CASP4 may be a potential prognostic biomarker of ccRCC.