Background and purpose: Epithelial ovarian cancer has the highest mortality rate of gynecologic cancers and overall survival rates have improved little in the last 20 to 30 years. CXXC finger protein 5 (CXXC5) plays an important role in AML (acute myeloid leukemia) and MDS (myelodysplasia). However

little is known about its clinical significance and biological function in epithelial ovarian cancer. This study aimed to investigate the expression of the CXXC5 in ovarian cancer and the effect of the CXXC5 on ES-2 cell proliferation. Methods: ①The alteration of CXXC5 in cancer genomics data of TCGA (Cancer Genome Atlas) was analyzed. ②The CXXC5 protein in the tissue chips was detected containing 37 benign ovarian cyst and 173 malignant tumor samples. The relationship between the expression of the CXXC5 with the clinicopathological features of patients with ovarian cancer was analyzed by SPSS software; ③The cells with the highest CXXC5 expression quantity from 5 ovarian cancer cells were selected by real- time quantitative PCR (qRT-PCR) and Western blot. ④ES-2 cells with shRNA stable transfection were construted using the strategy of lentivirus infection and analyzed cell proliferation by cell counting kit-8(CCK8). Results: ①Through the TCGA database

CXXC5 amplification was found in 7 of 563 cases. ②The CXXC5 expression in ovarian malignant carcinoma (39.3%) was higher than that in benign ovarian cyst (13.5%

P=0.003)

the histologic type was highly associated with CXXC5 (43% in serous

22.9% in mucinous

23.5% in endometrioid

67% in clear cell

P=0.014) and there was a significant correlation between CXXC5 and lymph node metastasis (positive vs negative

P=0.022). ③The ES-2 cells with shRNA stable transfection had a growth disadvantage (P0.05). Conclusion: The CXXC5 gene might have an advantage in proliferation of epithelial ovarian carcinoma and be expected to become the biomarker of poor prognosis.