EEF1A2 promotes HIF1A mediated breast cancer angiogenesis in normoxia and participates in a positive feedback loop with HIF1A in hypoxia.

Background: The eukaryotic elongation factor, EEF1A2, has been identified as an oncogene in various solid tumors. Here, we have identified a novel function of EEF1A2 in angiogenesis.

Methods: Chick chorioallantoic membrane, tubulogenesis, aortic ring, Matrigel plug, and skin wound healing assays established EEF1A2's role in angiogenesis.

Result: Higher EEF1A2 levels in breast cancer cells enhanced cell growth, movement, blood vessel function, and tubule formation in HUVECs, as confirmed by ex-ovo and in-vivo tests. The overexpression of EEF1A2 could be counteracted by Plitidepsin. Under normoxic conditions, EEF1A2 triggered HIF1A expression via ERK-Myc and mTOR signaling in TNBC and ER/PR positive cells. Hypoxia induced the expression of EEF1A2, leading to a positive feedback loop between EEF1A2 and HIF1A. Luciferase assay and EMSA confirmed HIF1A binding on the EEF1A2 promoter, which induced its transcription. RT-PCR and polysome profiling validated that EEF1A2 affected VEGF transcription and translation positively. This led to increased VEGF release from breast cancer cells, activating ERK and PI3K-AKT signaling in endothelial cells. Breast cancer tissues with elevated EEF1A2 showed higher microvessel density.

Conclusion: EEF1A2 exhibits angiogenic potential in both normoxic and hypoxic conditions, underscoring its dual role in promoting EMT and angiogenesis, rendering it a promising target for cancer therapy.