MicroRNA-653 Inhibits Thymocyte Proliferation and Induces Thymocyte Apoptosis in Mice with Autoimmune Myasthenia Gravis by Downregulating TRIM9

MicroRNA expression profiles of peripheral blood and mononuclear cells in myasthenia gravis: A systematic review

BACKGROUND

Studies have described the role of microRNAs (miRNAs) in thymic function, along with directly observing the altered expression of miRNAs in thymuses of myasthenia gravis (MG) patients; so, miRNAs became a core component in the pathophysiology of MG. However, because the miRNA analysis results are contradictory, the identification of MG-related miRNAs is daunting.

OBJECTIVE

We did a systematic review of studies analyzing the miRNA expression profile of peripheral blood and mononuclear cells for patients with MG.

METHODS

We ran a database search in PubMed, Scopus, and Web of Science on August 17, 2021. Original articles that analyzed miRNA profiles in peripheral blood (serum, plasma, and whole blood) and peripheral blood mononuclear cells (PBMCs) for patients with MG in comparison with a non-MG or healthy control (HC) group were eligible. The quality of studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2).

RESULTS

26 studies were included. The quality of studies was fair (median score, 5). Among 226 different miRNAs that were deregulated in at least one study (range, 1-87), ten miRNAs were significantly deregulated in three or more studies. Five miRNAs (50%) showed the same deregulation: miR-106b-3p and miR-21-5p were consistently upregulated, and miR-20b, miR-15b, and miR-16 were consistently downregulated. Also, there were five miRNAs that were mostly upregulated, miR-150-5p, miR-146a, miR-30e-5p, and miR-338-3p, or downregulated, miR-324-3p, across studies.

CONCLUSION

These miRNAs contribute to different pathways, importantly neural apoptosis and autophagy, inflammation, T regulatory cell development, and T helper cell balance. Prior to being used for diagnostic and therapeutic purposes, it is required to pursue molecular mechanisms these consistently and mostly dysregulated miRNAs specifically use in the context of MG.

miR-181a Ameliorates the Progression of Myasthenia Gravis by Regulating TRIM9

Abnormally activated CD4⁺ T cells are considered to be an important factor in the pathogenesis of myasthenia gravis (MG). In the pathogenesis of MG, the imbalance of proinflammatory cytokines and immune cells maintains the imbalance of immune response and inflammatory microenvironment. Studies have shown that miRNA is involved in the pathogenesis of MG. In our experiment, we extracted peripheral blood mononuclear cells (PBMCs) from MG patients and detected the expression of miR-181a and TRIM9 in PBMCs by qRT-PCR. In vitro experiments were conducted to explore the regulatory mechanism of miR-181a on target genes and its influence on inflammatory factors related to MG disease. Experimental autoimmune myasthenia gravis (EAMG) model mice are established, and the effects of miR-181a on EAMG symptoms and inflammatory factors are explored through in vivo experiments. According to a total of 40 EAMG mice that were successfully modeled, all EAMG mice showed symptoms of muscle weakness; their diet was reduced; their weight gain was slow; and even weight loss occurred. In MG patients and EAMG mice, the expression of miR-181a was low and TRIM9 was highly expressed. Bioinformatics website and dual-luciferase report analysis of miR-181a had a targeting relationship with TRIM9, and miR-181a could target the expression of TRIM9. After upregulating miR-181a or interfering with TRIM9, serum miR-181a in EAMG mice was significantly upregulated; TRIM9 was significantly downregulated; its clinical symptoms were reduced; and the expression of inflammatory factors was reduced. The study finally learned that miR-181a can reduce the level of MG inflammatory factors by targeting the expression of TRIM9 and has the effect of improving the symptoms of MG.

Emerging Role of Non-Coding RNAs in Regulation of T-Lymphocyte Function

T-lymphocytes (T cells) play a major role in adaptive immunity and current immune checkpoint inhibitor-based cancer treatments. The regulation of their function is complex, and in addition to cytokines, receptors and transcription factors, several non-coding RNAs (ncRNAs) have been shown to affect differentiation and function of T cells. Among these non-coding RNAs, certain small microRNAs (miRNAs) including miR-15a/16-1, miR-125b-5p, miR-99a-5p, miR-128-3p, let-7 family, miR-210, miR-182-5p, miR-181, miR-155 and miR-10a have been well recognized. Meanwhile, IFNG-AS1, lnc-ITSN1-2, lncRNA-CD160, NEAT1, MEG3, GAS5, NKILA, lnc-EGFR and PVT1 are among long non-coding RNAs (lncRNAs) that efficiently influence the function of T cells. Recent studies have underscored the effects of a number of circular RNAs, namely circ_0001806, hsa_circ_0045272, hsa_circ_0012919, hsa_circ_0005519 and circHIPK3 in the modulation of T-cell apoptosis, differentiation and secretion of cytokines. This review summarizes the latest news and regulatory roles of these ncRNAs on the function of T cells, with widespread implications on the pathophysiology of autoimmune disorders and cancer.

Identification of the regulatory role of lncRNA HCG18 in myasthenia gravis by integrated bioinformatics and experimental analyses

Background

Long non-coding RNAs (lncRNAs), functioning as competing endogenous RNAs (ceRNAs), have been reported to play important roles in the pathogenesis of autoimmune diseases. However, little is known about the regulatory roles of lncRNAs underlying the mechanism of myasthenia gravis (MG). The aim of the present study was to explore the roles of lncRNAs as ceRNAs associated with the progression of MG.

Methods

MG risk genes and miRNAs were obtained from public databases. Protein–protein interaction (PPI) network analysis and module analysis were performed. A lncRNA-mediated module-associated ceRNA (LMMAC) network, which integrated risk genes in modules, risk miRNAs and predicted lncRNAs, was constructed to systematically explore the regulatory roles of lncRNAs in MG. Through performing random walk with restart on the network, HCG18/miR-145-5p/CD28 ceRNA axis was found to play important roles in MG, potentially. The expression of HCG18 in MG patients was detected using RT-PCR. The effects of HCG18 knockdown on cell proliferation and apoptosis were determined by CCK-8 assay and flow cytometry. The interactions among HCG18, miR-145-5p and CD28 were explored by luciferase assay, RT-PCR and western blot assay.

Results

Based on PPI network, we identified 9 modules. Functional enrichment analyses revealed these modules were enriched in immune-related signaling pathways. We then constructed LMMAC network, containing 25 genes, 50 miRNAs, and 64 lncRNAs. Through bioinformatics algorithm, we found lncRNA HCG18 as a ceRNA, might play important roles in MG. Further experiments indicated that HCG18 was overexpressed in MG patients and was a target of miR-145-5p. Functional assays illustrated that HCG18 suppressed Jurkat cell apoptosis and promoted cell proliferation. Mechanistically, knockdown of HCG18 inhibited the CD28 mRNA and protein expression levels in Jurkat cells, while miR-145-5p inhibitor blocked the reduction of CD28 expression induced by HCG18 suppression.

Conclusion

We have reported a novel HCG18/miR-145-5p/CD28 ceRNA axis in MG. Our findings will contribute to a deeper understanding of the molecular mechanism of and provide a novel potential therapeutic target for MG.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03138-0.

miR‑653‑5p suppresses the growth and migration of breast cancer cells by targeting MAPK6

Breast cancer is the worldwide leading cause of cancer‑related deaths among women. Increasing evidence has demonstrated that microRNAs (miRNAs) play critical roles in the carcinogenesis and progression of breast cancer. miR‑653‑5p was previously reported to be involved in cell proliferation and apoptosis. However, the role of miR‑653‑5p in the progression of breast cancer has not been studied. In the present study, it was found that overexpression of miR‑653‑5p significantly inhibited the proliferation, migration and invasion of breast cancer cells in vitro. Moreover, overexpression of miR‑653‑5p promoted cell apoptosis in breast cancer by regulating the Bcl‑2/Bax axis and caspase‑9 activation. Additionally, the epithelial‑mesenchymal transition and activation of the Akt/mammalian target of rapamycin signaling pathway were also inhibited by miR‑653‑5p. Furthermore, the data demonstrated that miR‑653‑5p directly targeted mitogen‑activated protein kinase 6 (MAPK6) and negatively regulated its expression in breast cancer cells. Upregulation of MAPK6 could overcome the inhibitory effects of miR‑653‑5p on cell proliferation and migration in breast cancer. In conclusion, this study suggested that miR‑653‑5p functions as a tumor suppressor by targeting MAPK6 in the progression of breast cancer, and it may be a potential target for breast cancer therapy.

Emerging Roles of Dysregulated MicroRNAs in Myasthenia Gravis

Myasthenia gravis (MG) is a rare acquired autoimmune neuromuscular disease. Autoantibodies, cellular immunity, complement, and cytokines are involved in the pathogenesis of MG. It is characterized by the dysfunction of neuromuscular junction transmission and skeletal muscle weakness. MicroRNAs (miRNAs) are non-coding small molecule ribonucleic acids that regulate various biological processes (e.g., development, differentiation, and immunity) at the transcriptional and post-transcriptional levels of gene expression. miRNAs play an important regulatory role in the pathogenesis of autoimmune diseases, including MG. In recent studies, the functional mechanisms underlying the role of miRNAs in the pathogenesis of MG have received increasing attention. miRNAs are highly stable and have high specificity in peripheral body fluids. Therefore, the miRNAs in body fluids may represent promising biomarkers for determining the prognosis of MG and the efficacy of treatment. This article reviews the role of miRNAs in the pathogenesis of MG, highlights the potential of miRNAs as new biomarkers for the diagnosis of MG, and deepens our understanding of disease processes.

SOX30, a target gene of miR-653-5p, represses the proliferation and invasion of prostate cancer cells through inhibition of Wnt/β-catenin signaling

BACKGROUND

Sex-determining region Y-box containing gene 30 (SOX30) is a newly identified tumor-associated gene in several types of cancer. However, whether SOX30 is involved in the development and progression of prostate cancer remains unknown. This study investigated the potential role of SOX30 in prostate cancer.

METHODS

Prostate cancer cell lines and a normal prostate epithelial cell line were used for the experiments. The expression of SOX30 was determined using quantitative real-time PCR and western blot analysis. The malignant cellular behaviors of prostate cancer were assessed using the Cell Counting Kit-8, colony formation and Matrigel invasion assays. The miRNA-mRNA interaction was validated using the dual-luciferase reporter assay.

RESULTS

SOX30 expression was lower in cells of prostate cancer lines than in cells of the normal prostate epithelial line. Its overexpression repressed the proliferation and invasion of prostate cancer cells. SOX30 was identified as a target gene of microRNA-653-5p (miR-653-5p), which is upregulated in prostate cancer tissues. MiR-653-5p overexpression decreased SOX30 expression, while its inhibition increased SOX30 expression in prostate cancer cells. MiR-653-5p inhibition also markedly restricted prostate cancer cell proliferation and invasion. SOX30 overexpression or miR-653-5p inhibition significantly reduced β-catenin expression and downregulated the activation of Wnt/β-catenin signaling. SOX30 knockdown significantly reversed the miR-653-5p inhibition-mediated inhibitory effect on the proliferation, invasion and Wnt/β-catenin signaling in prostate cancer cells.

CONCLUSIONS

These results reveal a tumor suppressive function for SOX30 in prostate cancer and confirmed the gene as a target of miR-653-5p. SOX30 upregulation due to miR-653-5p inhibition restricted the proliferation and invasion of prostate cancer cells, and this was associated with Wnt/β-catenin signaling suppression. These findings highlight the importance of the miR-653-5p-SOX30-Wnt/β-catenin signaling axis in prostate cancer progression.