Alpha-difluoromethylornithine suppresses angiogenesis via the FLI1-CLEC14A-VEGFC pathway in retinal endothelial cells

Pathological angiogenesis is a leading cause of vision loss in blinding disorders such as age-related macular degeneration, in which anti-VEGF therapies are widely used, yet their limitations necessitate new therapeutic strategies. This study explores the molecular mechanisms through which alpha-difluoromethylornithine (DFMO), an inhibitor of polyamine synthesis, suppresses angiogenesis in human retinal microvascular endothelial cells (HRMECs). Transcriptome sequencing revealed that DFMO significantly reduced tube formation and downregulated 3839 genes, including C-type lectin domain-containing 14A (CLEC14A) and vascular endothelial growth factor C (VEGFC), both of which are implicated in angiogenic processes. Functional assays demonstrated that CLEC14A knockdown decreased VEGFC expression and impaired angiogenesis, whereas CLEC14A overexpression alleviated DFMO-induced downregulation of VEGFC. Moreover, bioinformatic analyses and dual-luciferase reporter assays identified Friend leukemia virus integration 1 (FLI1) as a direct transcriptional activator of CLEC14A. Knockdown of FLI1, but not STAT3, reduced CLEC14A expression, confirming the critical regulatory role of FLI1. In vivo studies confirmed upregulation of the FLI1-CLEC14A-VEGFC axis in the retina of a mouse model of choroidal neovascularization. In conclusion, these findings reveal that DFMO suppresses retinal angiogenesis via the FLI1-CLEC14A-VEGFC axis. This study provides new insights into the transcriptional regulation of angiogenesis and suggests potential molecular targets for treating neovascular retinal diseases.