Histidine-Rich Glycoprotein Inhibits TNF-α-Induced Tube Formation in Human Vascular Endothelial Cells

Omer Faruk Hatipoglu ¹ Takashi Nishinaka ¹ Kursat Oguz Yaykasli ² Shuji Mori ³ Masahiro Watanabe ³ Takao Toyomura ³ Masahiro Nishibori ⁴ Satoshi Hirohata ⁵ Hidenori Wake ^1* Hideo Takahashi ¹

• ¹ Kindai University Hospital, Osakasayama, Japan
• ² Friedrich-Alexander-University, Erlangen-Nürnberg, Germany
• ³ Shujitsu University, Okayama, Okayama, Japan
• ⁴ Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences,, Okayama, Japan
• ⁵ Graduate School of Health Sciences, Okayama University, Okayama, Japan

Tumor necrosis factor-α (TNF-α)-induced angiogenesis is a hallmark of tumor progression and metastasis, making it a crucial target for cancer therapy. Suppressing angiogenesis can effectively limit tumor growth and metastasis. Despite advancements in understanding angiogenic pathways, effective therapeutic strategies to inhibit TNF-α-mediated angiogenesis remain limited.Histidine-rich glycoprotein (HRG), a multifunctional plasma protein with potent antiangiogenic effects, holds significant promise in this regard. HRG levels are reduced in certain cancers, and this reduction may contribute to tumor development and progression.In this study, we investigated the antiangiogenic effects of HRG on TNF-α-stimulated human endothelial cells (EA.hy926). At physiological concentrations, HRG effectively reduced TNF-αinduced tube formation in vitro. Additionally, it downregulated the TNF-α-induced expression of integrins αV and β8 at the mRNA and protein levels. To elucidate the underlying mechanisms, we investigated the role of the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2), which is crucial for regulating oxidative stress responses and maintaining cellular homeostasis. HRG treatment progressively increased the nuclear translocation of NRF2. Treatment of cells with an NRF2 activator significantly suppressed TNF-α-induced tube formation and the expression of integrins αV and β8.Overall, our results indicate that the antiangiogenic activity of HRG is mediated by its ability to promote nuclear translocation of NRF2 and transcriptional activation, which in turn inhibits TNF-αinduced angiogenic signaling pathways, particularly those involving integrin αV and β8. Given the essential role of angiogenesis in tumor progression, HRG's ability to suppress pathological angiogenesis presents a promising avenue for developing novel cancer therapies.