OTOF Promotes Clear Cell Renal Cell Carcinoma Progression and Angiogenesis Through AKT-Dependent HIF/VEGFA Signaling

Background: Clear cell renal cell carcinoma (ccRCC) is characterized by marked molecular heterogeneity, aggressive clinical behavior, and prominent angiogenesis, highlighting the need to better understand the functional regulators underlying tumor progression and vascular remodeling. OTOF has previously been reported as a prognostically relevant gene in ccRCC; however, its biological function and potential involvement in tumor angiogenesis remain unclear. Methods: In the present study, we investigated the biological and pro-angiogenic roles of OTOF and explored the signaling pathways potentially involved. Results: Analysis of the TCGA-KIRC cohort confirmed that elevated OTOF expression was associated with unfavorable clinical outcomes. Functional experiments demonstrated that OTOF knockdown suppressed ccRCC cell proliferation, migration, and invasion and inhibited xenograft tumor growth. OTOF depletion also reduced intratumoral vascularization and impaired the ability of ccRCC cell-conditioned medium to promote HUVEC tube formation. Mechanistically, OTOF knockdown decreased VEGFA levels and was accompanied by reduced AKT phosphorylation and suppression of downstream HIF/VEGFA signaling. Pharmacological modulation of AKT signaling and VEGFA add-back experiments further supported the functional involvement of the AKT/HIF/VEGFA pathway in OTOF-associated angiogenesis. Conclusions: These findings extend previous observations regarding the prognostic relevance of OTOF by providing functional and mechanistic evidence that OTOF contributes to ccRCC progression and angiogenesis, at least in part, through AKT-dependent HIF/VEGFA signaling.