β‑elemene inhibits oxygen‑induced retinal neovascularization via promoting miR‑27a and reducing VEGF expression

Abstract

The present study aimed to investigate the significant role of β-elemene in mouse models of oxygen-induced retinopathy (OIR). C57BL/6J neonatal mice were used to establish OIR models. They were divided into four groups: Normoxia, OIR, OIR control and OIR-treated. Mice in the OIR group were exposed to 75±5% oxygen for 5 days and returned to a normal oxygen environment on postnatal day 12 (P12). The OIR treated group was intravitreally injected with 1 µl β-elemene on P12 and subsequently returned to a normal oxygen environment for 5 days (P12-P17). Retinas were obtained on P17. Retinal neovascularization (RNV) was detected using adenosine diphosphatase staining and analyzed by counting the nuclei of neovascular endothelial cells. Vascular endothelial growth factor (VEGF) expression was determined by reverse transcription-quantitative polymerase chain reaction, immunohistochemistry and western blot analysis. MicroRNA (miRNA/miR) microarrays were used to screen out differentially expressed miRNAs between the OIR and β-elemene-treated groups. Binding the 3′-untranslated region (UTR) of VEGF and miR-27a was confirmed using luciferase assays. It was found that high oxygen concentrations accelerated RNV and increased the number of preretinal neovascular cells; β-elemene treatment reduced these effects. VEGF mRNA and protein expression was higher in the OIR and OIR control groups, compared with the normoxia and OIR-treated groups. Further, it was shown that miR-22, miR-181a-1, miR-335-5p, miR-669n, miR-190b, miR-27a and miR-93 were upregulated in the OIR-treated group, and downregulated in the OIR group. The prediction websites TargetScan and miRanda revealed that VEGF contained a potential miR-27a binding site in its 3′-untranslated region (UTR). Luciferase assays demonstrated that miR-27a directly bound to the 3′-UTR of VEGF. In vitro experiments demonstrated that miR-27a inhibited VEGF expression. In addition, β-elemene treatment upregulate miR-27a expression in vivo and in vitro . When miR-27a expression was depleted by miR-27a inhibitor, the protective effect of β-elemene on RNV was eliminated. The present study demonstrated that β-elemene reduced RNV in mouse OIR models via miR-27a upregulation, leading to reduced VEGF expression. This finding may contribute to the development of novel therapeutic strategies for human retinopathy.

MiR-27a as a diagnostic biomarker and potential therapeutic target in systemic sclerosis

“…Another inhibitory effect of miR-27a on the TGF-β signaling pathway is mediated via direct targeting of TGF-βRI transcript (20). Also, major growth factors capable of contributing to brosis pathogenesis were found to be downregulated by miR-27a, including IGF-1 and VEGF (34,35). All of the aforementioned studies are in line with our results which strongly demonstrate the protective effect of miR-27a against brosis and hence SSc.…”

“…In this regard, Deng K, et al have shown the negative regulation of PPARγ by miR-27a, too (44). Besides, in a study conducted by Ji-Hoon Cho, et al with a systems biology approach, it was found that miR-27a along with miR-23a and miR24 is upregulated in response to TGF-β by ZEB-1 transcription factor which is a major participant in EMT (35). It could be suggested that miR-27a elevation in these instances may take place upon over-activation of the TGF-β signaling pathway as a negative feedback mechanism to attenuate its physiological consequences.…”

Transgenerational Transmission of 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) Effects in Human Granulosa Cells: The Role of MicroRNAs

“…In addition, VEGFB and VEGFC are part of two signaling pathways with major roles in tumor angiogenesis and lymphangiogenesis [75]. According to Zhang et al, VEGFB and VEGFC contain a potential miR-27a-3p binding site [76], and they were overexpressed in KGN cells.…”

MiR-27a as a diagnostic biomarker and potential therapeutic target in systemic sclerosis

“…Another inhibitory effect of miR-27a on the TGF-β signaling pathway is mediated via direct targeting of the TGF-βRI transcript 22 . Also, major growth factors capable of contributing to fibrosis pathogenesis were found to be downregulated by miR-27a, including IGF-1 and VEGF 40 , 41 . All of the aforementioned studies are in line with our results which strongly demonstrate the protective effect of miR-27a against fibrosis and hence SSc.…”