p53 and ANXA4/NF-κB p50 complexes regulate cell proliferation, apoptosis and tumor progression in ovarian clear cell carcinoma

Annexin IV (ANXA4) is highly expressed in ovarian clear cell carcinoma (OCCC); however, its underlying molecular mechanism in OCCC remains unknown. The present study aimed to identify the molecule that ANXA4 may act on and to determine its underlying molecular mechanism. Immunohistochemistry, co-immunoprecipitation and western blotting were performed to detect the expression and interaction of ANXA4, and its associated proteins. Furthermore, MTT assay, flow cytometry, western blotting and gene expression profile enrichment analysis were performed to identify the potential role and molecular mechanism of ANXA4 in OCCC. The results demonstrated that ANXA4 and nuclear factor-κ-light-chain-enhancer of activated B cells (NF-κB) p50 nuclear expression levels were significantly higher in OCCC tissues compared with other subtypes of ovarian cancer, such as serous and mucinous. In addition, a significantly positive correlation was observed between ANXA4 and NF-κB p50 expression in OCCC; however, the expression levels of mutant p53 and ANXA4 were negatively correlated in a linear manner. These results suggest that ANXA4 and NF-κB p50 may be potential independent risk factors for poor prognosis. ANXA4 and NF-κB p50 were demonstrated to interact and their expression was co-localized. The cBioPortal database was used to construct a protein-protein interaction network between ANXA4, NF-κB p50 and p53, and functional pathway analysis indicated that the genes were predominantly enriched in the cell cycle and during apoptosis. Transfection of the ANXA4 gene increased the expression of NF-κB p50, as well as its downstream targets, Cyclin D1 and B-cell lymphoma-2 (Bcl-2). Furthermore, transfection of the ANXA4 gene increased proliferation and decreased apoptosis of OCCC cells. Treatment with the NF-κB inhibitor, BAY 11-7082, decreased Cyclin D1 and Bcl-2 expression levels. Collectively, the results of the present study suggest that wild p53 activates ANXA4 transcription, promotes its expression and enhances NF-κB p50 and ANXA4 interaction. This in turn activates the NF-κB signaling pathway, promotes cell cycle progression and inhibits apoptosis, thus contributing to the malignant progression of OCCC. Thus, ANXA4 and NF-κB p50 may be used as prognostic biomarkers, and may be molecular therapeutic targets in OCCC.