Abstract
Metformin, an anti-diabetic drug commonly used for type 2 diabetes therapy, is associated with anti-angiogenic effects in conditions beyond diabetes. miR-21 has been reported to be involved in the process of angiogenesis. However, the precise regulatory mechanisms by which the metformin-induced endothelial suppression and its effects on miR-21-dependent pathways are still unclear. Bioinformatic analysis and identification of miR-21 and its targets and their effects on metformin-induced antiangiogenic activity were assessed using luciferase assays, quantitative real-time PCR, western blots, scratch assays, CCK-8 assays and tubule formation assays. In this study, miR-21 was strikingly downregulated by metformin in a time- and dose-dependent manner. miR-21 directly targeted the 3′-UTR of PTEN and SMAD7, and negatively regulated their expression. Overexpression of miR-21 abrogated the metformin-mediated inhibition of endothelial cells proliferation, migration, tubule formation and the TGF-β-induced AKT, SMAD- and ERK-dependent phosphorylations, and conversely, down-regulation of miR-21 aggravated metformin’s action and revealed significant promotion effects. Our study broadens our understanding of the regulatory mechanism of miR-21 mediating metformin-induced anti-angiogenic effects, providing important implications regarding the design of novel miRNA-based therapeutic strategies against angiogenesis.
Highlights
Metformin (N,N-dimethylbiguanide), an oral anti-hyperglycemic biguanide agent derived from Galega officinalis, has been used for decades in clinical therapy to treat metabolic disorders in type 2 diabetes (DM2) worldwide[1,2]
We found that miR-21 expression was downregulated significantly by metformin in a time- and doesdependent manner when compared with the control, and had expression nadirs at 24 h and 20 mM (Fig. 1A and B)
To better investigate whether metformin’ inhibitory effects on Human umbilical vein endothelial cells (HUVECs) migration could be associated with the expression level of miR-21, when transfection with miR-21 mimic/inhibitor and respective negative control (NC) given in combination with metformin treatment and 0.2% FBS (Fig. 2C,D), we found that inhibitor-induced miR-21 down-regulation caused a similar yet more effective inhibitory effect to metformin, and the migration inhibition was further down-regulated by another 21.6% compared to metformin alone, and otherwise, mimic-induced miR-21 over-expression can recover the metformin-inhibited HUVECs mobility, revealing a increase by another 16.4% compared to metformin alone
Summary
Metformin (N,N-dimethylbiguanide), an oral anti-hyperglycemic biguanide agent derived from Galega officinalis, has been used for decades in clinical therapy to treat metabolic disorders in type 2 diabetes (DM2) worldwide[1,2]. The mechanism of metformin on endothelial function and angiogenesis are possibly regulated through interfering of Akt-dependent signaling pathway, and prevent angiogenesisby reducing the pro-angiogenic, vascularisation, and levels of TGF-β11,11,12. All these studies seemed to show the mechanisms of how metformin mediates the interfering of endothelial cell proliferation, migration and angiogenesis, more recently, newer and deeper insights into these mechanisms have been reported that metformin impacts endothelial function and angiogenesis possibly via its modulation of miRNA expression[2,13,14]. Some basic and clinical researches have shown that miR-21 plays important roles in the angiogenesis inhibition, causing the inhibition of endothelial function, including cell proliferation and migration[16,19,20,21]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
