Astragaloside IV-induced BMSC exosomes promote neovascularization and protect cardiac function in myocardial infarction mice via the miR-411/HIF-1α axis

This study focused on investigating the mechanism of the astragaloside IV-induced bone marrow mesenchymal stem cell exosome (AS-IV-MSC-exo)/microRNA(miR)-411/HIF-1α axis in affecting vascular neovascularization and protecting cardiac function in myocardial infarction (MI) mice. Exosomes (MSC-exo and AS-IV-MSC-exo) were separated by differential centrifugation and then characterized. MI mouse models were established by left anterior descending coronary artery ligation. Echocardiography was used to evaluate cardiac function. HE staining and Masson staining were performed to observe myocardial histopathology. Capillary density in the myocardium via immunohistochemistry and quantified the expression of vascular endothelial growth factor (VEGF) via RT-qPCR. The expression of miR-411 and HIF-1α was tested by RT-qPCR and western blot and the targeting relationship of miR-411 and HIF-1α was verified by bioinformatics website and dual luciferase reporter gene assay. Exosomes with lipid bi-layer membrane structure, expressing exosomal surface marker proteins, and being taken up by cardiomyocytes could be successfully isolated utilizing ultracentrifugation. Intramyocardial injection of MSC-exo could restore cardiac function, decrease myocardial pathological changes and collagen deposition, and promote neovascularization in MI mice; the effect of AS-IV-MSC-exo was more significant. The ability of AS-IV-MSC-exo to restore cardiac function, lower myocardial pathological changes and collagen deposition, and promote neovascularization in MI mice was diminished when miR-411 expression in AS-IV-MSC-exo was reduced. Mechanistically, miR-411 was found to target and inhibit HIF-1α expression. Overexpression of HIF-1α impaired the impact of AS-IV-MSC-exo on improving cardiac function and promoting neovascularization in MI mice. AS-IV-MSC-exo improves cardiac function and promoted neovascularization via the miR-411/HIF-1α axis, thereby ameliorating MI.

Micro RNA-411 Expression Improves Cardiac Phenotype Following Myocardial Infarction in Mice

Induction of endogenous regenerative capacity has emerged as one promising approach to repair damaged hearts following myocardial infarction (MI). Re-expression of factors that are exclusively expressed during embryonic development may reactivate the ability of adult cardiomyocytes to regenerate. Here, we identified miR-411 as a potent inducer of cardiomyocyte proliferation. Overexpression of miR-411 in the heart significantly increased cardiomyocyte proliferation and survival in a model MI. We found that miR-411 enhances the activity of YAP, the main downstream effector of the Hippo pathway, in cardiomyocytes. In conclusion, miR-411 induces cardiomyocyte regeneration and improves cardiac function post-MI likely by modulating the Hippo/YAP pathway.

SNHG8 is upregulated in esophageal squamous cell carcinoma and directly sponges microRNA-411 to increase oncogenicity by upregulating KPNA2

Background

The long noncoding RNA, small nucleolar RNA host gene 8 (SNHG8), is upregulated in multiple human cancer types. However, whether SNHG8 is aberrantly expressed in esophageal squamous cell carcinoma (ESCC) and its biological functions have yet to be elucidated. Thus, we aimed to determine the expression status of SNHG8 in ESCC, explore the effects of SNHG8 on the oncogenicity of ESCC, and investigate the potential underlying mechanisms.

Methods

SNHG8 expression in ESCC tissues and cell lines was determined via reverse-transcription quantitative polymerase chain reaction. The actions of SNHG8 on the malignant characteristics of ESCC were explored using CCK-8 assay, flow-cytometric analysis, Transwell migration and invasion assays, and tumor xenografts in nude mice.

Results

SNHG8 expression was significantly higher in ESCC tissues and cell lines. High SNHG8 expression was revealed to closely correlate with primary tumor invasion depth, lymph node metastases, TNM stage, and worse overall survival among patients with ESCC. Functional investigation showed that ablation of SNHG8 notably restricted ESCC cell proliferation, migration, and invasion while inducing apoptosis in vitro and hindered tumor growth in vivo. In the meantime, SNHG8 acted as a molecular sponge of microRNA-411 (miR-411) in ESCC. Furthermore, miR-411 exerted a tumor-suppressive effect on ESCC cells, and karyopherin alpha 2 (KPNA2) turned out to be a direct target gene of miR-411. Restoring KPNA2 expression neutralized the inhibitory effects of miR-411 overexpression on the malignant behaviors of ESCC cells. Moreover, silencing of miR-411 abrogated the influence of SNHG8 downregulation in ESCC cells.

Conclusion

SNHG8 may play oncogenic roles in the malignancy of ESCC by sponging miR-411 to increase KPNA2 expression. The SNHG8–miR-411–KPNA2 pathway may be a novel target for the treatment of patients with ESCC and offer potential biomarkers for the diagnosis and prognosis of ESCC.