GBP2 inhibits pathological angiogenesis in the retina via the AKT/mTOR/VEGFA axis

Pathological retinal angiogenesis is not only the hallmark of retinopathies, but also a major cause of blindness. Guanylate binding protein 2 (GBP2) has been reported to be associated with retinal diseases such as diabetic retinopathy and hypoxic retinopathy. However, GBP2-mediated pathological retinal angiogenesis remains largely unknown. The present study aimed to investigate the role of GBP2 in pathological retinal angiogenesis and its underlying molecular mechanism. In this study, we established oxygen-induced retinopathy (OIR) mice model for in vivo study and hypoxia-induced angiogenesis in ARPE-19 cells for in vitro study. We demonstrated that GBP2 expression was markedly downregulated in the retina of mice with OIR and ARPE-19 cells treated with hypoxia, which was associated with pathological retinal angiogenesis. The regulatory mechanism of GBP2 in ARPE-19 cells was studied by GBP2 silencing and overexpression. The regulatory mechanism of GBP2 in the retina was investigated by overexpressing GBP2 in the retina of OIR mice. Mechanistically, GBP2 downregulated the expression and secretion of vascular endothelial growth factor (VEGFA) in ARPE-19 cells and retina of OIR mice. Interestingly, overexpression of GBP2 significantly inhibited neovascularization in OIR mice, conditioned medium of GBP2 overexpressing ARPE-19 cells inhibited angiogenesis in human umbilical vein endothelial cells (HUVECs). Furthermore, we confirmed that GBP2 downregulated VEGFA expression and angiogenesis by inhibiting the AKT/mTOR signaling pathway. Taken together, we concluded that GBP2 inhibited pathological retinal angiogenesis via the AKT/mTOR/VEGFA axis, thereby suggesting that GBP2 may be a therapeutic target for pathological retinal angiogenesis.

Guanylate-binding Protein 2 Expression Is Associated With Poor Survival and Malignancy in Clear-cell Renal Cell Carcinoma

BACKGROUND/AIM

Clear-cell renal cell carcinoma (ccRCC) is a common recalcitrant cancer. However, little is known about biomarkers of ccRCC. In the present study, we investigated the role of guanylate-binding protein 2 (GBP2), an interferon-induced GTPase, in ccRCC and its potential as a biomarker of this disease.

MATERIALS AND METHODS

GBP2 expression was analyzed using the Gene Expression Omnibus, The Cancer Genome Atlas, and Human Protein Atlas databases. Univariate and multivariate Cox-regression analyses were used to investigate the prognostic value of GBP2 in ccRCC. In addition, quantitative real-time polymerase chain reactions, western blotting, and immunohistochemistry were performed to confirm the expression of GBP2 in tissues from patients with ccRCC who had undergone radical nephrectomy at the Department of Urology, the First Affiliated Hospital of Chongqing Medical University (Chongqing, P. R. China). Cell-function assays were performed to investigate the effect of GBP2 on Caki-1 human kidney-cancer cells.

RESULTS

Bioinformatics and in vitro experiments showed that the expression of GBP2 was up-regulated in ccRCC tissues and cells and was positively correlated with the malignant clinicopathological parameters of the disease. Univariate and multivariate Cox-regression analyses showed that GBP2 expression was an independent risk factor for the prognosis of ccRCC. Cell-function assays showed that GBP2 expression promoted the proliferation, migration, and invasion of Caki-1 cells through the WNT/β-catenin signaling pathway.

CONCLUSION

The present results indicate that GBP2 expression may serve as a prognostic biomarker for ccRCC.