Abstract: Objective  To investigate the expression and clinical significance of mitochondrial calcium uptake 1（MICU1） in patients with renal clear cell carcinoma（RCCC）. Methods Cases of thirty patients with RCCC，who underwent radical nephrectomy in Yan'an University Affiliated Hospital from January 2016 to December 2018，were investigated. Immunohistochemical method was used to detect the expression of MICU1 protein in RCCC cancer tissues and adjacent normal tissues. Transient transfection was used to transfect the MICU1 interference fragment and the MICU1 overexpression plasmid into CAKI-1 cells（siMICU1 group and MICU1 group），respectively，and corresponding negative controls（siCtrl group and EV group） were set. Western blot was used to detect the expression of MICU1 protein，and MTS and EdU assays were used to detect the proliferation of CAKI-1 cells. The transcriptome data of 517 RCCC tissues in TCGA database were collected，and the relationship between MICU1 mRNA expression and clinicopathological characteristics and prognosis of RCCC patients were analyzed. Results The expression of MICU1 protein in RCCC tissues was lower than that in normal adjacent tissues（P<0.001）. The overexpressed MICU1 cells and interfered MICU1 cells were successfully constructed. MTS and EdU assays showed that the cell proliferation ability of the MICU1 group was lower than that of the EV group（P<0.05），and that of the siMICU1 group was higher than that of the siCtrl group（P<0.05）. TCGA database analysis showed that MICU1 expression was related to gender and TNM stage（P<0.05）； the survival rate of patients with low expression of MICU1 was lower than that of patients with high expression（χ²=19.290，P<0.001）； multivariate Cox regression showed that low expression of MICU1 was an independent risk factor affecting the overall survival of RCCC patients（HR=1.641，95%CI：1.191-2.261，P=0.002）. Conclusion MICU1 has a low expression in RCCC tissues and can promote the proliferation of RCCC cancer cells. 

Key words: Renal clear cell carcinoma, MICU1, Proliferation, Prognosis