ABSTRACT
Hepatocellular carcinoma (HCC) patients mostly suffer from poor survival outcomes. It is necessary to identify effective therapeutic targets to improve prognosis for HCC patients. Here, we report a new factor, CDCA2, in promoting HCC development. CDCA2 amplification is an independent risk factor for the recurrence and survival of HCC patients, which is positively correlated with elevated level of alpha-fetoprotein (AFP), high histological grade, large tumor size, advanced TNM stage, and poor prognosis for HCC patients. In HCC cells, CDCA2 promotes cell growth and inhibits apoptosis. Mechanistically, CDCA2's transcription is activated through the binding of E2F2/E2F8 with its promoter. CDCA2 depletion contributes to the suppression of cell proliferation and induction of apoptosis due to reactive oxygen species (ROS)-mediated stress, which can be reversed by antioxidants N-acetyl cysteine (NAC) and glutathione (GSH). Interestingly, we found that CDCA2 triggers the BRCA1-NRF2 cascade, which elevates antioxidant response and attenuates ROS levels. In response to oxidative stress, CDCA2 promotes BRCA1's chromatin relocalization to NRF2, activating NRF2-driven downstream signaling (HO-1, TXNRD1, and NQO1), which then protects HCC cells against oxidative damage. In conclusion, our results reveal that CDCA2 is a prognostic biomarker for HCC patients, and present the E2F2/E2F8-CDCA2-BRCA1-NRF2-ROS signaling axis that have implications for HCC therapeutics.
Subject(s)
BRCA1 Protein/metabolism , Carcinoma, Hepatocellular/metabolism , Carrier Proteins/metabolism , Cell Cycle Proteins/metabolism , Liver Neoplasms/metabolism , NF-E2-Related Factor 2/metabolism , Nuclear Proteins/metabolism , Oxidative Stress/physiology , Signal Transduction/physiology , Animals , Antioxidants/metabolism , Apoptosis/physiology , Carcinoma, Hepatocellular/pathology , Cell Line, Tumor , Cell Proliferation/physiology , Glutathione/metabolism , Hep G2 Cells , Humans , Liver Neoplasms/pathology , Male , Mice , Prognosis , Reactive Oxygen Species/metabolism , alpha-Fetoproteins/metabolismABSTRACT
Despite recent efforts to understand activities of POU domain class 2 transcription factor 1 (POU2F1), little is known about the roles of POU2F1 in hepatocellular carcinoma (HCC) tumorigenesis and its correlation with any clinicopathological feature of HCC. In this study, we found that POU2F1 was significantly up-regulated in HCC specimens compared with adjacent non-cancerous liver specimens. The high POU2F1 protein expression level positively correlated with large tumor size, high histological grade, tumor metastasis and advanced clinical stage, and HCC patients with high POU2F1 levels exhibited poor prognoses. We further demonstrated that POU2F1 over-expression promoted HCC cell proliferation, colony formation, epithelial-to-mesenchymal transition (EMT), migration and invasion, while silencing of POU2F1 inhibited these malignant phenotypes. POU2F1 induced the expression of Twist1, Snai1, Snai2 and ZEB1 genes which are involved in the regulation of EMT. Furthermore, POU2F1 was up-regulated by AKT pathway in HCC, and POU2F1 over-expression reversed the inhibition of malignant phenotypes induced by AKT knock-down, indicating POU2F1 is a key down-stream effector of AKT pathway. Collectively, our results indicate that POU2F1 over-expression is positively associated with aggressive phenotypes and poor survival in patients with HCC, and POU2F1 regulated by AKT pathway promotes HCC aggressive phenotypes by regulating the transcription of EMT genes. POU2F1 may be employed as a new prognostic factor and therapeutic target for HCC.
