Overexpression of UQCRC2 is correlated with tumor progression and poor prognosis in colorectal cancer.

Ubiquinol-cytochrome c reductase complex core protein 2 (UQCRC2) is an important subunit of mitochondrial respiratory complex III. However, its role in tumorigenesis and tumor progression remains unknown, especially with regards to colorectal cancer (CRC). In this research, we measured the expression of UQCRC2 protein by immunohistochemistry assay in 89 paired paraffin-embedded tumor tissues and corresponding adjacent normal tissues from patients with colorectal adenocarcinoma and investigated possible correlations of UQCRC2 expression with clinicopathological parameters and prognosis. We found that UQCRC2 was significantly upregulated in CRC tissues compared with adjacent normal tissues, and immunohistochemical UQCRC2 status was correlated to the depth of invasion (T), lymph node metastasis (N), advanced TNM stage. Multivariate analysis indicated that UQCRC2 remained an independent prognostic factor for poorer overall survival. Furthermore, we determined the role of UQCRC2-knockdown in CRC cells (RKO and HCT116) using lentivirus-mediated small hairpin RNAs (shRNAs). The effects of UQCRC2 knockdown on CRC cells (RKO and HCT116) proliferation were analyzed by cell proliferation and colony formation assay, and cell cycle and apoptosis were assessed by flow cytometry. We found that silencing UQCRC2 suppressed cell proliferation and colony formation in RKO and HCT116 cells, led to a cell cycle arrest and induced cell apoptosis in vitro. These results provided novel insights into the potential role of UQCRC2 in the tumorigenesis and progression of CRC, and revealed that UQCRC2 may serve as a new prognostic and therapeutic target in CRC.