Role of EFNAs in Shaping the Tumor Immune Microenvironment and Their Impact on Pancreatic Adenocarcinoma Prognosis.

PURPOSE: Due to the highly heterogeneous and immunosuppressed tumor microenvironment (TME), pancreatic adenocarcinoma (PAAD) has limited therapeutic options and an abysmal prognosis. Ephrin A 1-5 (EFNA1-5) have been shown to regulate tumorigenesis and metastasis in various cancers, but its role in PAAD remains unclear. METHODS: We comprehensively analyzed EFNA gene expression levels in pan-cancer and PAAD using the GEPIA and HPA databases. Then, we assessed the prognostic value of EFNA1-5 using the Kaplan-Meier plotter and nomogram model. Further exploration of the association of EFNA1-5 with clinicopathological features of PAAD used information from the UALCAN database, and the TIMER dataset was used to reveal the correlation between EFNA1-5 and the tumor immune microenvironment (TIME) of pancreatic cancer. In addition, cBioPortal Databases, GSEA, and GSCALite were used to explore gene changes, protein interactions, and biological functions. Finally, the oncogenic effect of EFNA5 was verified in vivo and in vitro. RESULTS: The expression levels of EFNA1-5 were significantly upregulated in PAAD. The expression of EFNA1/3/4/5 were significantly associated with overall survival (OS) and relapse-free survival (RFS) in PAAD patients. The high expression of EFNA2-5 were related to poor clinical features, such as higher tumor stage or grade and a wider range of lymph node metastasis. EFNA1-5 were closely associated with immune cell infiltration, CAFs, and MDSCs expression. Furthermore, EFNA5 is an independent risk factor for poor prognosis in PAAD patients, and it can promote the malignant progression of pancreatic cancer in vitro and in vivo. CONCLUSION: Differential expression of EFNA1-5 is associated with TIME in pancreatic cancer, predicts different survival outcomes, and maybe a novel prognostic marker reflecting an immunosuppressive state and a potential therapeutic target.