Ephrin-A3 Promotes Hepatocellular Carcinoma Cell Proliferation and Metastasis by Interacting with EphA2

Abstract

Background: Emerging evidence suggests that Eph/ephrin-system involves different facets of tumorigenesis and cancer progression. Whether ephrin-A3, a cognate ligand to several Eph receptors, plays a role in HCC cell proliferation and metastasis remains unclear. Methods: The expression of ephrin-A3 was detected by immunohistochemistry and qRT-PCR in human HCC tissues. The clinical significance of ephrin-A3 was analyzed using multiple databases. The biological functions of ephrin-A3 were investigated in vitro and in vivo. Immunofluorescence and co-immunoprecipitation were used to detect the interaction between ephrin-A3 and EphA2. Findings: Elevated expression of ephrin-A3 was positively correlated with the histological grade, metastasis and poor prognosis in human HCC. Knockdown of ephrin-A3 led to significantly decreased proliferative activity and metastatic potential, and re-introduction of ephrin-A3 rescued the decreased proliferation, migration, and invasion induced by ephrin-A3 knockdown in HCC cells. Ephrin-A3 interacted with EphA2 and positively regulated EphA2 and AKT phosphorylation. Knockdown of EphA2 attenuated HCC cell proliferation, migration, and invasion induced by ephrin-A3 overexpression. Furthermore, ephrin-A3-induced EphA2 phosphorylation is both a substrate and a positive regulator of AKT. In HCC tissues, ephrin-A3 expression was positively correlated with EphA2, and patients with high co-expression of ephrin-A3 and EphA2 exhibited poorer prognosis. Interpretation: Ephrin-A3 promotes HCC metastasis by interacting with EphA2 and activating EphA2 and AKT. Thus, our study implicates ephrin-A3 and EphA2 as potential prognostic biomarkers, and provides valuable information for HCC prognosis and treatment. Funding Statement: This work was supported in part by grants from the National Natural Science Foundation of China (81672832), Outstanding Subject Leader Training Program of Shanghai Municipal Commission of Health and Family Planning (2018BR20), the National Natural Science Foundation of Shanghai (20ZR1454000), the National Key Sci-Tech Special Project of China (2018ZX10723204-006), the Research Project of Shanghai Municipal Commission of Health and Family Planning (20204Y0093), and the Grants from the State Key Laboratory of Oncogenes and Related Genes (91-17-18). Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: The study was approved by the Research Ethics Committee of Renji Hospital, Shanghai Jiao Tong University School of Medicine, and informed consent was obtained from each patient from the Zhejiang University (Hangzhou, China) and the Qidong Liver Cancer Institute (Qidong, China).