Objective. Long noncoding RNAs (lncRNAs), including some members of small nucleolar RNA host gene (SNHG), are important regulators in myocardial injury, while the role of SNHG4 in myocardial infarction (MI) is rarely known. This study is aimed at exploring the regulatory role and mechanisms of SNHG4 on MI. Methods. Cellular and rat models of MI were established. The expression of relating genes was measured by qRT-PCR and/or western blot. In vitro, cell viability was detected by MTT assay, and cell apoptosis was assessed by caspase-3 level, Bax/Bcl-2 expression, and/or flow cytometry. The inflammation was evaluated by TNF-α, IL-1β, and IL-6 levels. The myocardial injury in MI rats was evaluated by echocardiography, TTC/HE/MASSON/TUNEL staining, and immunohistochemistry (Ki67). DLR assay was performed to confirm the target relationships. Results. SNHG4 was downregulated in hypoxia-induced H9c2 cells and MI rats, and its overexpression enhanced cell viability and inhibited cell apoptosis and inflammation both in vitro and in vivo. SNHG4 overexpression also decreased infarct and fibrosis areas, relieved pathological changes, and improved heart function in MI rats. In addition, miR-148b-3p was an action target of SNHG4, and its silencing exhibited consistent results with SNHG4 overexpression in vitro. DUSP1 was a target of miR-148b-3p, which inhibited the apoptosis of hypoxia-induced H9c2 cells. Both miR-148b-3p overexpression and DUSP1 silencing weakened the effects of SNHG4 overexpression on protecting H9c2 cells against hypoxia. Conclusions. Overexpression of SNHG4 relieved MI through regulating miR-148b-3p/DUSP1, providing potential therapeutic targets.
Background Triple-negative breast cancer (TNBC) is the subtype of advanced breast cancer with the shortest survival time and the poorest prognosis, and treatment options are relatively limited. Exosomes, small extracellular vesicles enriched with bioactive molecules, are critical mediators of intercellular communication and have been implicated in cancer progression. The aim of this study was to investigate the molecular mechanism of exosomes promoting the proliferation and migration of TNBC. Methods In this study, exosomes were identified by Flow cytometry and transmission electron microscopy, and RNA sequencing (RNA-seq) was used to identify differentially expressed genes and downstream regulatory molecules in exosomes. RNA-seq results were supported by bioinformatics analysis and Western blot analysis. Functional assays including in vivo tumor formation, Colony formation Assay, Scratch migration and transwell assays were performed to study exosomes related phenomena and mechanism. Results Serum-derived exosomes from patients with TNBC can induce TNBC progression in vitro and in vivo . lncRNA SNHG4 was most significantly up-regulated in exosomes, and overexpression of lncRNA SNHG4 significantly promoted the proliferation and migration of TNBC cells. In addition, lncRNA SNHG4 promotes TNBC cell proliferation and migration by upregulating the expression of Exportin 5(XPO5). Silencing XPO5 can effectively attenuate the tumor-promoting effect of serum exosomes in TNBC patients. Mechanistically, lncRNA SNHG4 acts through XPO5-mediated pathways. Silencing XPO5 can effectively inhibit the tumor-promoting effect mediated by lncRNA SNHG4. Conclusions Taken together, our study revealed that the exosome lncRNA SNHG4 exerts its oncogenic role by activating XPO5-mediated pathways, thereby regulating TNBC cell proliferation and migration. This can be considered as a potential target for TNBC molecular therapy.
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