Cytochrome C inhibits tumor growth and predicts favorable prognosis in clear cell renal cell carcinoma

Cytochrome C (Cyto C), a multifunctional enzyme, has been demonstrated to be associated with cell apoptosis and respiration. Accumulating evidence has revealed that serum Cyto C is an effective indicator in evaluating the effect of chemotherapy. However, to the best of our knowledge, the clinical significance of Cyto C and its role in cell growth and apoptosis in clear cell renal cell carcinoma (CCRCC) remain unknown. In the present study, Cyto C expression was detected in 150 CCRCC and 30 normal tissues samples via immunohistochemistry. The results demonstrated that Cyto C protein expression levels in CCRCC tissues were downregulated compared with those in corresponding normal tissues. In addition, it was revealed that Cyto C expression was negatively associated with TNM stage. Further analyses revealed that patients with CCRCC and low Cyto C expression levels had a shorter survival time than those with high Cyto C expression. Multivariate analyses indicated that high Cyto C expression levels were an independent prognostic factor for survival. Functionally, overexpression of Cyto C effectively suppressed the growth of CCRCC cells and induced cell apoptosis, and knockdown of Cyto C reversed these effects. Finally, overexpression of Cyto C inhibited the tumor growth of CCRCC cells in vivo. Overall, the data of the present study indicated that Cyto C may be a novel prognostic biomarker and acted as a regulator of tumor growth in CCRCC.