Profiles of Circulating MiRNAs Following Metformin Treatment in Patients with Type 2 Diabetes

Targeting the Epigenetic Marks in Type 2 Diabetes Mellitus: Will Epigenetic Therapy Be a Valuable Adjunct to Pharmacotherapy?

Although genetic, environmental, and lifestyle factors largely contribute to type 2 diabetes mellitus (T2DM) risk, the role of epigenetics in its pathogenesis is now well established. The epigenetic mechanisms in T2DM mainly consist of DNA methylation, histone modifications and regulation by noncoding RNAs (ncRNAs). For instance, DNA methylation at CpG islands in the promoter regions of specific genes encoding insulin signaling and glucose metabolism suppresses these genes. Modulating the enzyme mediators of these epigenetic marks aims to restore standard gene expression patterns and improve glycemic control. In targeting these epigenetic marks, using epigenetic drugs such as DNA methyltransferase (DNAMT), histone deacetylase (HDAC) and histone acetyltransferase (HAT) inhibitors has led to variable success in humans and experimental murine models. Specifically, the United States' Food and Drug Administration (US FDA) has approved DNAMT inhibitors like 5-azacytidine and 5-aza-2'-deoxycytidine for use in diabetic retinopathy: a T2DM microvascular complication. These DNAMT inhibitors block the genes for methylation of mitochondrial superoxide dismutase 2 (SOD2) and matrix metallopeptidase 9 (MMP-9): the epigenetic marks in diabetic retinopathy. Traditional pharmacotherapy with metformin also have epigenetic effects in T2DM and positively alter disease outcomes when combined with epigenetic drugs like DNAMT and HDAC inhibitors, raising the prospect of using epigenetic therapy as a valuable adjunct to pharmacotherapy. However, introducing small interfering RNAs (siRNAs) in cells to silence specific target genes remains in the exploratory phase. Future research should focus on regulating gene expression in T2DM using long noncoding RNA (lncRNA) molecules, another type of ncRNA. This review discusses the epigenetics of T2DM and that of its macro- and microvascular complications, and the potential benefits of combining epigenetic therapy with pharmacotherapy for optimal results.

The role of microRNAs in pregnancies complicated by maternal diabetes

With the global prevalence of diabetes increasing, more people of reproductive age are experiencing hyperglycaemic pregnancies. Maternal Type 1 (T1DM) or Type 2 (T2DM) diabetes mellitus, and gestational diabetes mellitus (GDM) are associated with maternal cardiovascular and metabolic complications. Pregnancies complicated by maternal diabetes also increase the risk of short- and long-term health complications for the offspring, including altered fetal growth and the onset of T2DM and cardiometabolic diseases throughout life. Despite advanced methods for improving maternal glucose control, the prevalence of adverse maternal and offspring outcomes associated with maternal diabetes remains high. The placenta is a key organ at the maternal-fetal interface that regulates fetal growth and development. In pregnancies complicated by maternal diabetes, altered placental development and function has been linked to adverse outcomes in both mother and fetus. Emerging evidence suggests that microRNAs (miRNAs) are key molecules involved in mediating these changes. In this review, we describe the role of miRNAs in normal pregnancy and discuss how miRNA dysregulation in the placenta and maternal circulation is associated with suboptimal placental development and pregnancy outcomes in individuals with maternal diabetes. We also discuss evidence demonstrating that miRNA dysregulation may affect the long-term health of mothers and their offspring. As such, miRNAs are potential candidates as biomarkers and therapeutic targets in diabetic pregnancies at risk of adverse outcomes.

Detailed role of Let-7e in human diseases

As part of the epigenetic machinery, microRNAs (miRNAs) are extensively utilized by eukaryotes. By modulating gene expression in a variety of ways, these short RNAs mediate crucial physiological processes. This suggests that abnormalities in miRNA biogenesis and expression can be traced back to a variety of diseases. In addition, miRNAs are promising clinical candidates, especially for preclinical diagnosis. The Let family of miRNAs was one of the first to be discovered. As a prominent member of this category, extensive research has been conducted on Let-7e. The vast majority of evidence indicates an association between let-7e dysregulation and the onset and progression of disease, including malignancies. Because their effect depends on the genetic profile of disease and the affected tissue, different miRNAs play diverse roles in various diseases. However, what counts in miRNA studies is that just one miRNA may target numerous mRNAs in a cell at the exact time, therefore summarizing the effect of a single miRNA in human diseases can provide better insights into disease detection and treatment. The goal of this study is to gain a deeper understanding of how let-7e functions in human cells so that it can be utilized more effectively in clinical settings for diagnosis, prognosis, and treatment. We have reviewed the research on let-7e, focusing on the molecular underpinnings of biological processes controlled by this miRNA that contribute to the development and etiology of numerous disorders.

Plasma Extracellular MicroRNAs Associated With Cardiovascular Disease Risk Factors in Middle-Aged and Older Adults

BACKGROUND

Extracellular microRNAs (miRNAs) are a class of noncoding RNAs that remain stable in the extracellular milieu, where they contribute to various physiological and pathological processes by facilitating intercellular signaling. Previous studies have reported associations between miRNAs and cardiovascular diseases (CVDs); however, the plasma miRNA signatures of CVD and its risk factors have not been fully elucidated at the population level.

METHODS AND RESULTS

Plasma miRNA levels were measured in 4440 FHS (Framingham Heart Study) participants. Linear regression analyses were conducted to test the cross-sectional associations of each miRNA with 8 CVD risk factors. Prospective analyses of the associations of miRNAs with new-onset obesity, hypertension, type 2 diabetes, CVD, and all-cause mortality were conducted using proportional hazards regression. Replication was carried out in 1999 RS (Rotterdam Study) participants. Pathway enrichment analyses were conducted and target genes were predicted for miRNAs associated with ≥5 risk factors in the FHS. In the FHS, 6 miRNAs (miR-193b-3p, miR-122-5p, miR-365a-3p, miR-194-5p, miR-192-5p, and miR-193a-5p) were associated with ≥5 risk factors. This miRNA signature was enriched for pathways associated with CVD and several genes annotated to these pathways were predicted targets of the identified miRNAs. Furthermore, miR-193b-3p, miR-194-5p, and miR-193a-5p were each associated with ≥2 risk factors in the RS. Prospective analysis revealed 8 miRNAs associated with all-cause mortality in the FHS.

CONCLUSIONS

These findings highlight associations between miRNAs and CVD risk factors that may provide valuable insights into the underlying pathogenesis of CVD.

Metformin improves diabetic neuropathy by reducing inflammation through up-regulating the expression of miR-146a and suppressing oxidative stress

PURPOSE

Diabetic neuropathy (DN) is a notable complication of diabetes mellitus. The potential involvement of miR-146a in DN regulation is presently under investigation. Metformin, a commonly prescribed medication for diabetes, is the primary therapeutic intervention. This study aimed to unveil the potential protective effects of metformin on diabetic neuropathy and explore the mechanisms underlying its action.

METHOD

Six-weeks male Sprague Dawley rats (n = 40) were randomly divided into 5 groups. The rat model of diabetic neuropathy (DN) was established by administering streptozotocin (STZ). To investigate the effects on the sciatic nerve and resident Schwann cells (RSCs), metformin and miR-146a mimics were administered, and our research explored the potential underlying mechanism.

RESULT

The sciatic nerve samples obtained from diabetic rats exhibited noticeable morphological damage, accompanied by decreased miR-146a expression (2.61 ± 0.11 vs 5.0 ± 0.3, p < 0.01) and increased inflammation levels (p65: 1.89 ± 0.04 vs 0.82 ± 0.05, p < 0.01; TNF-α: 0.93 ± 0.03 vs 0.33 ± 0.03, p < 0.01). Notably, the administration of metformin effectively ameliorated the structural alterations in the sciatic nerve by suppressing the inflammatory pathway (p65: 1.15 ± 0.05 vs 1.89 ± 0.04, p < 0.01; TNF-α: 0.67 ± 0.04 vs 0.93 ± 0.03, p < 0.01) and reducing oxidative stress (NO: 0.062 ± 0.004 vs 0.154 ± 0.004umol/mg, p < 0.01; SOD: 3.08 ± 0.09 vs 2.46 ± 0.09 U/mg, p < 0.01). The miR-146a mimics intervention group exhibited comparable findings.

CONCLUSION

This study's findings implied that metformin can potentially mitigate diabetic neuropathy in rats through the modulation of miR-146a expression.

MicroRNAs Associated with Metformin Treatment in the Diabetes Prevention Program

The Diabetes Prevention Program (DPP) randomized controlled trial demonstrated that metformin treatment reduced progression to type 2 diabetes (T2D) by 31% compared to placebo in adults with prediabetes. Circulating micro-ribonucleic acids (miRs) are promising biomarkers of T2D risk, but little is known about their associations with metformin regimens for T2D risk reduction. We compared the change in 24 circulating miRs from baseline to 2 years in a subset from DPP metformin intervention (n = 50) and placebo (n = 50) groups using Wilcoxon signed rank tests. Spearman correlations were used to evaluate associations between miR change and baseline clinical characteristics. Multiple linear regression was used to adjust for covariates. The sample was 73% female, 17% Black, 13% Hispanic, and 50 ± 11 years. Participants were obese, normotensive, prediabetic, and dyslipidemic. Change in 12 miR levels from baseline to 2 years was significantly different in the metformin group compared with placebo after adjusting for multiple comparisons: six (let-7c-5p, miR-151a-3p, miR-17-5p, miR-20b-5p, miR-29b-3p, and miR-93-5p) were significantly upregulated and six (miR-130b-3p, miR-22-3p, miR-222-3p, miR-320a-3p, miR-320c, miR-92a-3p) were significantly downregulated in the metformin group. These miRs help to explain how metformin is linked to T2D risk reduction, which may lead to novel biomarkers, therapeutics, and precision health strategies.

Metformin: From Diabetes to Cancer-Unveiling Molecular Mechanisms and Therapeutic Strategies

Metformin, a widely used anti-diabetic drug, has garnered attention for its potential in cancer management, particularly in breast and colorectal cancer. It is established that metformin reduces mitochondrial respiration, but its specific molecular targets within mitochondria vary. Proposed mechanisms include inhibiting mitochondrial respiratory chain Complex I and/or Complex IV, and mitochondrial glycerophosphate dehydrogenase, among others. These actions lead to cellular energy deficits, redox state changes, and several molecular changes that reduce hyperglycemia in type 2 diabetic patients. Clinical evidence supports metformin's role in cancer prevention in type 2 diabetes mellitus patients. Moreover, in these patients with breast and colorectal cancer, metformin consumption leads to an improvement in survival outcomes and prognosis. The synergistic effects of metformin with chemotherapy and immunotherapy highlights its potential as an adjunctive therapy for breast and colorectal cancer. However, nuanced findings underscore the need for further research and stratification by molecular subtype, particularly for breast cancer. This comprehensive review integrates metformin-related findings from epidemiological, clinical, and preclinical studies in breast and colorectal cancer. Here, we discuss current research addressed to define metformin's bioavailability and efficacy, exploring novel metformin-based compounds and drug delivery systems, including derivatives targeting mitochondria, combination therapies, and novel nanoformulations, showing enhanced anticancer effects.

View on Metformin: Antidiabetic and Pleiotropic Effects, Pharmacokinetics, Side Effects, and Sex-Related Differences

Metformin is a synthetic biguanide used as an antidiabetic drug in type 2 diabetes mellitus, achieved by studying the bioactive metabolites of Galega officinalis L. It is also used off-label for various other diseases, such as subclinical diabetes, obesity, polycystic ovary syndrome, etc. In addition, metformin is proposed as an add-on therapy for several conditions, including autoimmune diseases, neurodegenerative diseases, and cancer. Although metformin has been used for many decades, it is still the subject of many pharmacodynamic and pharmacokinetic studies in light of its extensive use. Metformin acts at the mitochondrial level by inhibiting the respiratory chain, thus increasing the AMP/ATP ratio and, subsequently, activating the AMP-activated protein kinase. However, several other mechanisms have been proposed, including binding to presenilin enhancer 2, increasing GLP1 release, and modification of microRNA expression. Regarding its pharmacokinetics, after oral administration, metformin is absorbed, distributed, and eliminated, mainly through the renal route, using transporters for cationic solutes, since it exists as an ionic molecule at physiological pH. In this review, particular consideration has been paid to literature data from the last 10 years, deepening the study of clinical trials inherent to new uses of metformin, the differences in effectiveness and safety observed between the sexes, and the unwanted side effects. For this last objective, metformin safety was also evaluated using both VigiBase and EudraVigilance, respectively, the WHO and European databases of the reported adverse drug reactions, to assess the extent of metformin side effects in real-life use.

Effects of a High-Fat Diet on Insulin-Related miRNAs in Plasma and Brain Tissue in APPSwe/PS1dE9 and Wild-Type C57BL/6J Mice

Insulin resistance (IR)-related miRNAs have been associated with the development and progression of Alzheimer's disease (AD). The dietary modulation of these miRNAs could become a potential strategy to manage AD. The aim of this study was to evaluate the effect of a high-fat diet (HFD), which aggravates AD-related pathogenic processes, on serum, cortex and hippocampus IR-related miRNA expression. C57BL/6J WT and APPSwe/PS1dE9 mice were fed either an HFD or a conventional diet till 6 months of age. The mice fed with the HFD showed a significant increase in body weight and worsening glucose and insulin metabolism. miR-19a-3p was found to be up-regulated in the cortex, hippocampus and serum of APP/PS1 mice and in the serum and hippocampus of WT mice fed with the HFD. miR-34a-5p and miR-146a-5p were up-regulated in the serum of both groups of mice after consuming the HFD. Serum miR-29c-3p was overexpressed after consuming the HFD, along with hippocampal miR-338-3p and miR-125b-5p, only in WT mice. The HFD modulated the expression of peripheral and brain miRNAs related to glucose and insulin metabolism, suggesting the potential role of these miRNAs not only as therapeutic targets of AD but also as peripheral biomarkers for monitoring AD.

Emerging roles of microRNAs as diagnostics and potential therapeutic interest in type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a metabolic disease of impaired glucose utilization. Uncontrolled high sugar levels lead to advanced glycation end products (AGEs), which affects several metabolic pathways by its receptor of advanced glycation end products (RAGE) and causes diabetic complication. MiRNAs are small RNA molecules which regulate genes linked to diabetes and affect AGEs pathogenesis, and target tissues, influencing health and disease processes.

AIM

To explore miRNA roles in T2DM's metabolic pathways for potential therapeutic and diagnostic advancements in diabetes complications.

METHODS

We systematically searched the electronic database PubMed using keywords. We included free, full-length research articles that evaluate the role of miRNAs in T2DM and its complications, focusing on genetic and molecular disease mechanisms. After assessing the full-length papers of the shortlisted articles, we included 12 research articles.

RESULTS

Several types of miRNAs are linked in metabolic pathways which are affected by AGE/RAGE axis in T2DM and its complications. miR-96-5p, miR-7-5p, miR-132, has_circ_0071106, miR-143, miR-21, miR-145-5p, and more are associated with various aspects of T2DM, including disease risk, diagnostic markers, complications, and gene regulation.

CONCLUSION

Targeting the AGE/RAGE axis, with a focus on miRNA regulation, holds promise for managing T2DM and its complications. MiRNAs have therapeutic potential as they can influence the metabolic pathways affected by AGEs and RAGE, potentially reducing inflammation, oxidative stress, and vascular complications. Additionally, miRNAs may serve as early diagnostic biomarkers for T2DM. Further research in this area may lead to innovative therapeutic strategies for diabetes and its associated complications.

MicroRNAs Associated with Metformin Treatment in the Diabetes Prevention Program

The Diabetes Prevention Program (DPP) randomized controlled trial demonstrated that metformin treatment reduced progression to type 2 diabetes (T2D) by 31% compared to placebo in adults with prediabetes. Circulating micro-ribonucleic acids (miRs) are promising biomarkers of T2D risk, but little is known about their associations with metformin regimens for T2D risk reduction. We compared the change in 24 circulating miRs from baseline to 2 years in a subset from DPP metformin intervention (n = 50) and placebo (n = 50) groups using Wilcoxon signed rank tests. Spearman's correlations were used to evaluate associations between miR change and baseline clinical characteristics. Multiple linear regression was used to adjust for covariates. The sample was 73% female, 17% Black, 13% Hispanic, and 50 ± 11 years. Participants were obese, normotensive, prediabetic, and dyslipidemic. Change in 12 miR levels from baseline to 2 years was significantly different in the metformin group compared with placebo after adjusting for multiple comparisons: six (let-7c-5p, miR-151a-3p, miR-17-5p, miR-20b-5p, miR-29b-3p, and miR-93-5p) were significantly upregulated and six (miR-130b-3p, miR-22-3p, miR-222-3p, miR-320a-3p, miR-320c, miR-92a-3p) were significantly downregulated in the metformin group. These miRs help to explain how metformin is linked to T2D risk reduction, which may lead to novel biomarkers, therapeutics, and precision-health strategies.

Combining bioinformatics and machine learning algorithms to identify and analyze shared biomarkers and pathways in COVID-19 convalescence and diabetes mellitus

Background

Most patients who had coronavirus disease 2019 (COVID-19) fully recovered, but many others experienced acute sequelae or persistent symptoms. It is possible that acute COVID-19 recovery is just the beginning of a chronic condition. Even after COVID-19 recovery, it may lead to the exacerbation of hyperglycemia process or a new onset of diabetes mellitus (DM). In this study, we used a combination of bioinformatics and machine learning algorithms to investigate shared pathways and biomarkers in DM and COVID-19 convalescence.

Methods

Gene transcriptome datasets of COVID-19 convalescence and diabetes mellitus from Gene Expression Omnibus (GEO) were integrated using bioinformatics methods and differentially expressed genes (DEGs) were found using the R programme. These genes were also subjected to Gene Ontology (GO) functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis to find potential pathways. The hub DEGs genes were then identified by combining protein-protein interaction (PPI) networks and machine learning algorithms. And transcription factors (TFs) and miRNAs were predicted for DM after COVID-19 convalescence. In addition, the inflammatory and immune status of diabetes after COVID-19 convalescence was assessed by single-sample gene set enrichment analysis (ssGSEA).

Results

In this study, we developed genetic diagnostic models for 6 core DEGs beteen type 1 DM (T1DM) and COVID-19 convalescence and 2 core DEGs between type 2 DM (T2DM) and COVID-19 convalescence and demonstrated statistically significant differences (p<0.05) and diagnostic validity in the validation set. Analysis of immune cell infiltration suggests that a variety of immune cells may be involved in the development of DM after COVID-19 convalescence.

Conclusion

We identified a genetic diagnostic model for COVID-19 convalescence and DM containing 8 core DEGs and constructed a nomogram for the diagnosis of COVID-19 convalescence DM.

Glimepiride Compared to Liraglutide Increases Plasma Levels of miR-206, miR-182-5p, and miR-766-3p in Type 2 Diabetes Mellitus: A Randomized Controlled Trial

BACKGRUOUND

Diabetes is a chronic disease with several long-term complications. Several glucose-lowering drugs are used to treat type 2 diabetes mellitus (T2DM), e.g., glimepiride and liraglutide, in which both having different modes of action. Circulating microRNAs (miRNAs) are suggested as potential biomarkers that are associated with the disease development and the effects of the treatment. In the current study we evaluated the effect of glimepiride, liraglutide on the expression of the circulating miRNAs.

METHODS

The present study is a post hoc trial from a previously randomized control trial comparing liraglutide versus glimepiride both in combination with metformin in subjects with T2DM, and subclinical heart failure. miRNAs were determined in the subjects' serum samples with next generation sequencing. Expression patterns of the circulating miRNAs were analyzed using bioinformatic univariate and multivariate analyses (clinical trial registration: NCT01425580).

RESULTS

Univariate analyses show that treatment with glimepiride altered expression of three miRNAs in patient serum, miR-206, miR-182-5p, and miR-766-3p. Both miR-182-5p and miR-766-3p were also picked up among the top contributing miRNAs with penalized regularised logistic regressions (Lasso). The highest-ranked miRNAs with respect to Lasso coefficients were miR-3960, miR-31-5p, miR-3613-3p, and miR-378a-3p. Liraglutide treatment did not significantly influence levels of circulating miRNAs.

CONCLUSION

Present study indicates that glucose-lowering drugs differently affect the expression of circulating miRNAs in serum in individuals with T2DM. More studies are required to investigate possible mechanisms by which glimepiride is affecting the expression of circulating miRNAs.

Metformin regulates the effects of IR and IGF-1R methylation on mast cell activation and airway reactivity in diabetic rats with asthma through miR-152-3p/DNMT1 axis

BACKGROUND/AIM

Metformin is a drug for treating type 2 diabetes mellitus (T2DM). Recently, metformin has been shown to reduce the risks of asthma-associated outcomes and asthma deterioration, thereby holding promise as a superior medicine for diabetic patients with asthma. However, the mechanism by which metformin reduces diabetic asthma is yet to be clarified. This study aimed at ascertaining the downstream molecules underlying the effect of metformin on the activation of mast cells (MCs) and airway reactivity in a concomitant diabetic and asthmatic rat model.

METHODS

A T2DM model was induced utilizing a high-fat diet and streptozotocin. Then, 10% ovalbumin was utilized to stimulate asthma-like pathology in the T2DM rats. RBL-2H3 cells were induced by anti-dinitrophenyl-specific immunoglobulin E for constructing an in vitro model. Luciferase assay and RNA immunoprecipitation (IP) assay were conducted to identify the interaction between microRNA-152-3p (miR-152-3p) and DNA methyltransferase 1 (DNMT1), while chromatin IP to identify the binding of DNMT1 to insulin receptor (IR) and insulin-like growth factor 1 receptor (IGF-1R) promoters. The effects of metformin on both pathological changes in vivo and biological behaviors of cells were evaluated. Using gain- and loss-of-function approaches, we assessed the role of the two interactions in the metformin-induced effect.

RESULTS

It was suggested that metformin could impede the MC activation and airway resistance in the concomitant diabetic and asthmatic rats. Additionally, metformin downregulated IR and IGF-1R through DNMT1-dependent methylation to repress MC activation and airway resistance. DNMT1 was testified to be a target gene of miR-152-3p. Furthermore, miR-152-3p-induced silencing of DNMT1 was blocked by metformin, hence restraining MC activation and airway resistance.

CONCLUSION

The findings cumulatively demonstrate that metformin downregulates IR/IGF-1R to block MC activation and airway resistance via impairing the binding affinity between miR-152-3p and DNMT1.

A Review of micro RNAs changes in T2DM in animals and humans

Type 2 diabetes mellitus (T2DM) and its associated complications have become a crucial public health concern in the world. According to the literature, chronic inflammation and the progression of T2DM have a close relationship. Accumulated evidence suggests that inflammation enhances the insulin secretion lost by islets of Langerhans and the resistance of target tissues to insulin action, which are two critical features in T2DM development. Based on recently highlighted research that plasma concentration of inflammatory mediators such as tumor necrosis factor α and interleukin-6 are elevated in insulin-resistant and T2DM, and it raises novel question marks about the processes causing inflammation in both situations. Over the past few decades, microRNAs (miRNAs), a class of short, noncoding RNA molecules, have been discovered to be involved in the regulation of inflammation, insulin resistance, and T2DM pathology. These noncoding RNAs are specifically comprised of RNA-induced silencing complexes and regulate the expression of specific protein-coding genes through various mechanisms. There is extending evidence that describes the expression profile of a special class of miRNA molecules altered during T2DM development. These modifications can be observed as potential biomarkers for the diagnosis of T2DM and related diseases. In this review study, after reviewing the possible mechanisms involved in T2DM pathophysiology, we update recent information on the miRNA roles in T2DM, inflammation, and insulin resistance.

Insights into the Role of Plasmatic and Exosomal microRNAs in Oxidative Stress-Related Metabolic Diseases

A common denominator of metabolic diseases, including type 2 diabetes Mellitus, dyslipidemia, and atherosclerosis, are elevated oxidative stress and chronic inflammation. These complex, multi-factorial diseases are caused by the detrimental interaction between the individual genetic background and multiple environmental stimuli. The cells, including the endothelial ones, acquire a preactivated phenotype and metabolic memory, exhibiting increased oxidative stress, inflammatory gene expression, endothelial vascular activation, and prothrombotic events, leading to vascular complications. There are different pathways involved in the pathogenesis of metabolic diseases, and increased knowledge suggests a role of the activation of the NF-kB pathway and NLRP3 inflammasome as key mediators of metabolic inflammation. Epigenetic-wide associated studies provide new insight into the role of microRNAs in the phenomenon of metabolic memory and the development consequences of vessel damage. In this review, we will focus on the microRNAs related to the control of anti-oxidative enzymes, as well as microRNAs related to the control of mitochondrial functions and inflammation. The objective is the search for new therapeutic targets to improve the functioning of mitochondria and reduce oxidative stress and inflammation, despite the acquired metabolic memory.

Overexpression of microRNA-21-5p and microRNA-221-5p in Monocytes Increases the Risk of Developing Coronary Artery Disease

MicroRNAs (miRs) regulate gene expression at the post-transcriptional level and are found to be present in monocytes. This study aimed to investigate miR-221-5p, miR-21-5p, and miR-155-5p, their expression in monocytes, and their role in coronary arterial disease (CAD). The study population comprised 110 subjects, and RT-qPCR was used to examine the miR-221-5p, miR-21-5p, and miR-155-5p expressions in monocytes. Results: the miR-21-5p (p = 0.001) and miR-221-5p (p < 0.001) expression levels were significantly higher in the CAD group, and the miR-155-5p (p = 0.021) expression levels were significantly lower in the CAD group; only miR-21-5p and miR-221-5p upregulation was found to be associated with an increased CAD risk. The results show significant increases in miR-21-5p in the unmedicated CAD group with the metformin patients vs. the healthy control group (p = 0.001) and vs. the medicated CAD group with metformin (p = 0.022). The same was true for miR-221-5p in the CAD patients unmedicated with metformin vs. the healthy control group (p < 0.001). Our results from Mexican CAD patients show that the overexpression in monocytes of miR-21-5p and miR-221-5p increases the risk of the development of CAD. In addition, in the CAD group, the metformin downregulated the expression of miR-21-5p and miR-221-5p. Also, the expression of endothelial nitric oxide synthase (NOS3) decreased significantly in our patients with CAD, regardless of whether they were medicated. Therefore, our findings allow for the proposal of new therapeutic strategies for the diagnosis and prognosis of CAD and the evaluation of treatment efficacy.

An increase in the expression of circulating miR30d-5p and miR126-3p is associated with intermediate hyperglycaemia in Iranian population

Type 2 diabetes is the most prevalent metabolic disease worldwide. The disease is characterised by high blood glucose levels and recently it has been shown that changes in the plasma levels of several miRNAs (miRNA) are associated with the disease. Interestingly, alterations in circulating miRNAs occur years before the onset of the disease and demonstrate predictive power. In this study, we carried out RT-qPCR to examine the plasma levels of two type 2 diabetes specific miRNAs, miR-30d-5p and miR-126-3p in an Iranian population of non-diabetic control individuals, subjects with intermediate hyperglycaemia and type 2 diabetic individuals with hyperglycaemia. We found that the plasma levels of miR-30d and miR-126 increase by 3.1 and 11.16 times, respectively, in individuals with intermediate hyperglycaemia compared to non-diabetic controls. However, no significant changes in the expression of these two miRNAs have been observed between type 2 diabetic individuals and non-diabetic subjects. Our results confirm that alterations in the plasma levels of miR-30d-5p and miR-126-3p could be used as diagnostic markers of type 2 diabetes in the Iranian population as well.

Downregulation of plasma microRNA-29c-3p expression may be a new risk factor for diabetic retinopathy

BACKGROUND

Circulation miRNAs have emerged as new biomarkers for identifying and monitoring the microvascular complications of diabetes. The aim of this study is to evaluate the levels of five candidate miRNAs (miR-29c-3p, miR-18a, miR-31, miR-181 and miR-20a) in patients with diabetic retinopathy (DR) and their relationship with disease severity.

METHODS

The study included 31 diabetes patients without DR (NDR group), 68 patients with DR (DR group) and 30 healthy controls (HC group). Twenty-five of patients with DR were proliferative DR (PDR group) and 43 were non-proliferative DR (NPDR group) patients. Metabolic parameters and serum vascular endothelial growth factor (VEGF) levels of all participants were measured. Circulating miRNAs levels were determined by quantitative real-time PCR. Fundus examinations of all patients were performed by a single ophthalmologist.

RESULTS

VEGF levels were significantly higher in the NDR, and DR groups compared to HC group (P=0.011 and P=0.014, respectively). Plasma miR-29c-3p was downregulated in diabetic patients with retinopathy and without retinopathy. This downregulation was more prominent in diabetic patients without retinopathy compared to those with retinopathy (P=0.016). There was no significant difference in plasma levels of miR-18a, miR-20a, miR-18a and miR-31 between diabetic subjects with and without retinopathy (P>0.05). There was no correlation between DR severity and the levels of miRNAs (P>0.05). In multivariate logistic regression analysis, it was found that changes in plasma miR-29c-3p expression of diabetic patients increased DR risk independent of other risk factors.

CONCLUSIONS

Plasma miR-29c-3p expression is downregulated in diabetic patients with and without retinopathy, and changes in this miRNA are an independent risk factor for the development of DR.

miR-24-3p and Body Mass Index as Type 2 Diabetes Risk Factors in Spanish Women 15 Years after Gestational Diabetes Mellitus Diagnosis

Gestational diabetes mellitus (GDM) is defined as any degree of glucose intolerance that is diagnosed for the first time during pregnancy. The objective of this study is to know the glucose tolerance status after 15 years of pregnancy in patients diagnosed with gestational diabetes and to assess the long-term effect of GDM on the circulating miRNA profile of these women. To answer these, 30 randomly selected women diagnosed with GDM during 2005-2006 were included in the study, and glucose tolerance was measured using the National Diabetes Data Group criteria. Additionally, four miRNAs (hsa-miR-1-3p, hsa-miR-24-3p, hsa-miR-329-3p, hsa-miR-543) were selected for their analysis in the plasma of women 15 years after the diagnosis of GDM. In our study we discovered that, fifteen years after the diagnosis of GDM, 50% of women have some degree of glucose intolerance directly related to body weight and body mass index during pregnancy. Dysglycemic women also showed a significantly increased level of circulating hsa-miR-24-3p. Thus, we can conclude that initial weight and BMI, together with circulating expression levels of hsa-miR-24-3p, could be good predictors of the future development of dysglycemia in women with a previous diagnosis of GDM.

Anthocyanin-rich extract from black beans exerts anti-diabetic effects in rats through a multi-genomic mode of action in adipose tissue

Black beans (BB) are an important source of a range of plant bioactive compounds including polyphenols, particularly anthocyanins. Several studies support that consumption of BB is associated with health benefits, including prevention of type 2 diabetes mellitus (T2DM). However, molecular mechanisms underlying the potential health properties of BB on adipose tissue (AT) are still largely unknown. The purpose of this study was to investigate multi-genomic effects of BB intake and identify regulatory networks potentially mediating T2DM on AT. Male Wistar diabetic rats consumed an anthocyanin-rich black bean extract for 5 weeks. Global gene expression from AT, protein coding and non-coding RNA profiles were determined using RNAseq. Biological function analyses were performed using a variety of bioinformatic tools. The evaluation of global gene expression profiles exhibited significant change following BB consumption with 406 significantly differentially expressed genes, 33 miRNA and 39 lncRNA and 3 snRNA. Functional analyses indicated that these genes play an important role in regulation of PI3K signaling, NIN/NF-kB signaling, insulin secretion, and endoplasmic reticulum (ER) organization. Interestingly, transcription factors such as GATA2, or POU2AF1 demonstrated to modulate their activity by BB extract by direct interaction with polyphenol metabolites, or by interactions with cell signaling proteins, like PKB, AKT or PI3K, that could control transcription factor activity and as a result impact on adipogenesis regulation. Therefore, the constant consumption of an anthocyanin-rich black bean extract may have anti-diabetic protective effects by modulating gene expression, resulting in a promising alternative for T2DM patients.

Anthocyanin-rich extract from black beans exerts anti-diabetic effects in rats through a multi-genomic mode of action in adipose tissue

Black beans (BB) are an important source of a range of plant bioactive compounds including polyphenols, particularly anthocyanins. Several studies support that consumption of BB is associated with health benefits, including prevention of type 2 diabetes mellitus (T2DM). However, molecular mechanisms underlying the potential health properties of BB on adipose tissue (AT) are still largely unknown. The purpose of this study was to investigate multi-genomic effects of BB intake and identify regulatory networks potentially mediating T2DM on AT. Male Wistar diabetic rats consumed an anthocyanin-rich black bean extract for 5 weeks. Global gene expression from AT, protein coding and non-coding RNA profiles were determined using RNAseq. Biological function analyses were performed using a variety of bioinformatic tools. The evaluation of global gene expression profiles exhibited significant change following BB consumption with 406 significantly differentially expressed genes, 33 miRNA and 39 lncRNA and 3 snRNA. Functional analyses indicated that these genes play an important role in regulation of PI3K signaling, NIN/NF-kB signaling, insulin secretion, and endoplasmic reticulum (ER) organization. Interestingly, transcription factors such as GATA2, or POU2AF1 demonstrated to modulate their activity by BB extract by direct interaction with polyphenol metabolites, or by interactions with cell signaling proteins, like PKB, AKT or PI3K, that could control transcription factor activity and as a result impact on adipogenesis regulation. Therefore, the constant consumption of an anthocyanin-rich black bean extract may have anti-diabetic protective effects by modulating gene expression, resulting in a promising alternative for T2DM patients.

Cardiovascular Disease-Associated MicroRNAs as Novel Biomarkers of First-Trimester Screening for Gestational Diabetes Mellitus in the Absence of Other Pregnancy-Related Complications

We assessed the diagnostic potential of cardiovascular disease-associated microRNAs for the early prediction of gestational diabetes mellitus (GDM) in singleton pregnancies of Caucasian descent in the absence of other pregnancy-related complications. Whole peripheral venous blood samples were collected within 10 to 13 weeks of gestation. This retrospective study involved all pregnancies diagnosed with only GDM (n = 121) and 80 normal term pregnancies selected with regard to equality of sample storage time. Gene expression of 29 microRNAs was assessed using real-time RT-PCR. Upregulation of 11 microRNAs (miR-1-3p, miR-20a-5p, miR-20b-5p, miR-23a-3p, miR-100-5p, miR-125b-5p, miR-126-3p, miR-181a-5p, miR-195-5p, miR-499a-5p, and miR-574-3p) was observed in pregnancies destinated to develop GDM. Combined screening of all 11 dysregulated microRNAs showed the highest accuracy for the early identification of pregnancies destinated to develop GDM. This screening identified 47.93% of GDM pregnancies at a 10.0% false positive rate (FPR). The predictive model for GDM based on aberrant microRNA expression profile was further improved via the implementation of clinical characteristics (maternal age and BMI at early stages of gestation and an infertility treatment by assisted reproductive technology). Following this, 69.17% of GDM pregnancies were identified at a 10.0% FPR. The effective prediction model specifically for severe GDM requiring administration of therapy involved using a combination of these three clinical characteristics and three microRNA biomarkers (miR-20a-5p, miR-20b-5p, and miR-195-5p). This model identified 78.95% of cases at a 10.0% FPR. The effective prediction model for GDM managed by diet only required the involvement of these three clinical characteristics and eight microRNA biomarkers (miR-1-3p, miR-20a-5p, miR-20b-5p, miR-100-5p, miR-125b-5p, miR-195-5p, miR-499a-5p, and miR-574-3p). With this, the model identified 50.50% of GDM pregnancies managed by diet only at a 10.0% FPR. When other clinical variables such as history of miscarriage, the presence of trombophilic gene mutations, positive first-trimester screening for preeclampsia and/or fetal growth restriction by the Fetal Medicine Foundation algorithm, and family history of diabetes mellitus in first-degree relatives were included in the GDM prediction model, the predictive power was further increased at a 10.0% FPR (72.50% GDM in total, 89.47% GDM requiring therapy, and 56.44% GDM managed by diet only). Cardiovascular disease-associated microRNAs represent promising early biomarkers to be implemented into routine first-trimester screening programs with a very good predictive potential for GDM.

Dysregulated miRNAs network in the critical COVID-19: An important clue for uncontrolled immunothrombosis/thromboinflammation

Known as a pivotal immunohemostatic response, immunothrombosis is activated to restrict the diffusion of pathogens. This beneficial intravascular defensive mechanism represents the close interaction between the immune and coagulation systems. However, its uncontrolled form can be life-threatening to patients with the critical coronavirus disease 2019 (COVID-19). Hyperinflammation and ensuing cytokine storm underlie the activation of the coagulation system, something which results in the provocation of more immune-inflammatory responses by the thrombotic mediators. This vicious cycle causes grave clinical complications and higher risks of mortality. Classified as an evolutionarily conserved family of the small non-coding RNAs, microRNAs (miRNAs) serve as the fine-tuners of genes expression and play a key role in balancing the pro/anticoagulant and pro-/anti-inflammatory factors maintaining homeostasis. Therefore, any deviation from their optimal expression levels or efficient functions can lead to severe complications. Despite their extensive effects on the molecules and processes involved in uncontrolled immunothrombosis, some genetic agents and uncontrolled immunothrombosis-induced interfering factors (e.g., miRNA-single nucleotide polymorphysms (miR-SNPs), the complement system components, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, and reactive oxygen species (ROS)) have apparently disrupted their expressions/functions. This review study aims to give an overview of the role of miRNAs in the context of uncontrolled immunothrombosis/thromboinflammation accompanied by some presumptive interfering factors affecting their expressions/functions in the critical COVID-19. Detecting, monitoring, and resolving these interfering agents mafy facilitate the design and development of the novel miRNAs-based therapeutic approaches to the reduction of complications incidence and mortality in patients with the critical COVID-19.

Circulating microRNAs as clinically useful biomarkers for Type 2 Diabetes Mellitus: miRNomics from bench to bedside

Type 2 diabetes (T2D), a chronic metabolic disease, has attained the status of a global epidemic with steadily increasing incidence worldwide. Improved diagnosis, stratification and prognosis of T2D patients and the development of more effective treatments are needed. In this era of personalized medicine, the discovery and evaluation of innovative circulating biomarkers can be an effective tool for better stratification, prognosis and therapeutic selection/management of T2D patients. MicroRNAs (miRNAs), a class of small non-coding RNAs that modulate gene expression, have been investigated as potential circulating biomarkers in T2D. Several studies have investigated the expression of circulating miRNAs in T2D patients from various biological fluids, including plasma and serum, and have demonstrated their potential as diagnostic and prognostic biomarkers, as well as biomarkers of response to therapy. In this review, we provide an overview of the current state of knowledge, focusing on circulating miRNAs that have been consistently expressed in at least two independent studies, in order to identify a set of consistent biomarker candidates in T2D. The expression levels of miRNAs, correlation with clinical parameters, functional roles of miRNAs and their potential as biomarkers are reported. A systematic literature search and assessment of studies led to the selection and review of 10 miRNAs (miR-126-3p, miR-223-3p, miR-21-5p, miR-15a-5p, miR-24-3p, miR-34a-5p, miR-146a-5p, miR-148a-3p, miR-30d-5p and miR-30c-5p). We also present technical challenges and our thoughts on the potential validation of circulating miRNAs and their application as biomarkers in the context of T2D.

Understanding the Role of GLUT2 in Dysglycemia Associated with Fanconi-Bickel Syndrome

Fanconi−Bickel Syndrome (FBS) is a rare disorder of carbohydrate metabolism that is characterized by the accumulation of glycogen mainly in the liver. It is inherited in an autosomal recessive manner due to mutations in the SLC2A2 gene. SLC2A2 encodes for the glucose transporter GLUT2 and is expressed in tissues that are involved in glucose homeostasis. The molecular mechanisms of dysglycemia in FBS are still not clearly understood. In this study, we report two cases of FBS with classical phenotypes of FBS associated with dysglycemia. Genomic DNA was extracted and analyzed by whole-genome and Sanger sequencing, and patient PBMCs were used for molecular analysis. One patient had an exonic SLC2A2 mutation (c.1093C>T in exon 9, R365X), while the other patient had a novel intronic SLC2A2 mutation (c.613-7T>G). Surprisingly, the exonic mutation resulted in the overexpression of dysfunctional GLUT2, resulting in the dysregulated expression of other glucose transporters. The intronic mutation did not affect the coding sequence of GLUT2, its expression, or glucose transport activity. However, it was associated with the expression of miRNAs correlated with type 1 diabetes mellitus, with a particular significant overexpression of hsa-miR-29a-3p implicated in insulin production and secretion. Our findings suggest that SLC2A2 mutations cause dysglycemia in FBS either by a direct effect on GLUT2 expression and/or activity or, indirectly, by the dysregulated expression of miRNAs implicated in glucose homeostasis.

The role of MicroRNA networks in tissue-specific direct and indirect effects of metformin and its application

Metformin is a first-line oral antidiabetic agent that results in clear benefits in relation to glucose metabolism and diabetes-related complications. The specific regulatory details and mechanisms underlying these benefits are still unclear and require further investigation. There is recent mounting evidence that metformin has pleiotropic effects on the target tissue development in metabolic organs, including adipose tissue, the gastrointestinal tract and the liver. The mechanism of actions of metformin are divided into direct effects on target tissues and indirect effects via non-targeted tissues. MicroRNAs (miRNAs) are a class of endogenous, noncoding, negative gene regulators that have emerged as important regulators of a number of diseases, including type 2 diabetes mellitus (T2DM). Metformin is involved in many aspects of miRNA regulation, and metformin treatment in T2DM should be associated with other miRNA targets. A large number of miRNAs regulation by metformin in target tissues with either direct or indirect effects has gradually been revealed in the context of numerous diseases and has gradually received increasing attention. This paper thoroughly reviews the current knowledge about the role of miRNA networks in the tissue-specific direct and indirect effects of metformin. Furthermore, this knowledge provides a novel theoretical basis and suggests therapeutic targets for the clinical treatment of metformin and miRNA regulators in the prevention and treatment of cancer, cardiovascular disorders, diabetes and its complications.

Identification of candidate biomarkers and pathways associated with type 1 diabetes mellitus using bioinformatics analysis

Type 1 diabetes mellitus (T1DM) is a metabolic disorder for which the underlying molecular mechanisms remain largely unclear. This investigation aimed to elucidate essential candidate genes and pathways in T1DM by integrated bioinformatics analysis. In this study, differentially expressed genes (DEGs) were analyzed using DESeq2 of R package from GSE162689 of the Gene Expression Omnibus (GEO). Gene ontology (GO) enrichment analysis, REACTOME pathway enrichment analysis, and construction and analysis of protein–protein interaction (PPI) network, modules, miRNA-hub gene regulatory network and TF-hub gene regulatory network, and validation of hub genes were performed. A total of 952 DEGs (477 up regulated and 475 down regulated genes) were identified in T1DM. GO and REACTOME enrichment result results showed that DEGs mainly enriched in multicellular organism development, detection of stimulus, diseases of signal transduction by growth factor receptors and second messengers, and olfactory signaling pathway. The top hub genes such as MYC, EGFR, LNX1, YBX1, HSP90AA1, ESR1, FN1, TK1, ANLN and SMAD9 were screened out as the critical genes among the DEGs from the PPI network, modules, miRNA-hub gene regulatory network and TF-hub gene regulatory network. Receiver operating characteristic curve (ROC) analysis confirmed that these genes were significantly associated with T1DM. In conclusion, the identified DEGs, particularly the hub genes, strengthen the understanding of the advancement and progression of T1DM, and certain genes might be used as candidate target molecules to diagnose, monitor and treat T1DM.

Metformin: Expanding the Scope of Application-Starting Earlier than Yesterday, Canceling Later

Today the area of application of metformin is expanding, and a wealth of data point to its benefits in people without carbohydrate metabolism disorders. Already in the population of people leading an unhealthy lifestyle, before the formation of obesity and prediabetes metformin smooths out the adverse effects of a high-fat diet. Being prescribed at this stage, metformin will probably be able to, if not prevent, then significantly reduce the progression of all subsequent metabolic changes. To a large extent, this review will discuss the proofs of the evidence for this. Another recent important change is a removal of a number of restrictions on its use in patients with heart failure, acute coronary syndrome and chronic kidney disease. We will discuss the reasons for these changes and present a new perspective on the role of increasing lactate in metformin therapy.

Blood-derived miRNA levels are not correlated with metabolic or anthropometric parameters in obese pre-diabetic subjects but with systemic inflammation

As blood-derived miRNAs (c-miRNAs) are modulated by exercise and nutrition, we postulated that they might be used to monitor the effects of a lifestyle intervention (LI) to prevent diabetes development. To challenge this hypothesis, obese Asian Indian pre-diabetic patients were submitted to diet modifications and physical activity for 4 months (LI group) and compared to a control group which was given recommendations only. We have considered 2 periods of time to analyze the data, i.e.; a first one to study the response to the intervention (4 months), and a second one post-intervention (8 months). At basal, 4 months and 8 months post-intervention the levels of 17 c-miRNAs were quantified, selected either for their relevance to the pathology or because they are known to be modulated by physical activity or diet. Their variations were correlated with variations of 25 metabolic and anthropometric parameters and cytokines. As expected, fasting-glycaemia, insulin-sensitivity, levels of exercise- and obesity-induced cytokines were ameliorated after 4 months. In addition, the levels of 4 miRNAs (i.e.; miR-128-3p, miR-374a-5p, miR-221-3p, and miR-133a-3p) were changed only in the LI group and were correlated with metabolic improvement (insulin sensitivity, cytokine levels, waist circumference and systolic blood pressure). However, 8 months post-intervention almost all ameliorated metabolic parameters declined indicating that the volunteers did not continue the protocol on their own. Surprisingly, the LI positive effects on c-miRNA levels were still detected, and were even more pronounced 8 months post-intervention. In parallel, MCP-1, involved in tissue infiltration by immune cells, and Il-6, adiponectin and irisin, which have anti-inflammatory effects, continued to be significantly and positively modified, 8 months post-intervention. These data demonstrated for the first time, that c-miRNA correlations with metabolic parameters and insulin sensitivity are in fact only indirect and likely associated with the level systemic inflammation. More generally speaking, this important result explains the high variability between the previous studies designed to identify specific c-miRNAs associated with the severity of insulin-resistance. The results of all these studies should take into account the level of inflammation of the patients. In addition, this finding could also explain why, whatever the pathology considered (i.e.; cancers, diabetes, neurodegenerative disorders, inflammatory diseases) the same subset of miRNAs is always found altered in the blood of patients vs healthy subjects, as these pathologies are all associated with the development of inflammation.

Versatile role of miR-24/24-1*/24-2* expression in cancer and other human diseases

MiRNAs (miRs) have been proven to be well-validated therapeutic targets. Emerging evidence has demonstrated that intricate, intrinsic and paradoxical functions of miRs are context-dependent because of their multiple upstream regulators, broad spectrum of downstream molecular targets and distinct expression in various tissues, organs and disease states. Targeted therapy has become an emerging field of research. One key for the development of successful miR-based/targeted therapy is to acquire integrated knowledge of its regulatory network and its association with disease phenotypes to identify critical nodes of the underlying pathogenesis. Herein, we systematically summarized the comprehensive role of miR-24-3p (miR-24), along with its passenger strands miR-24-1-5p* (miR-24-1) and miR-24-2-5p* (miR-24-2), emphasizing their microenvironment, intracellular targets, and associated gene networks and regulatory phenotypes in 18 different cancer types and 13 types of other disorders. MiR-24 targets and regulates numerous genes in various cancer types and enhances the expression of several oncogenes (e.g., cMyc, BCL2 and HIF1), which are challenging in terms of druggability. In contrast, several tumor suppressor proteins (p21 and p53) have been reported to be downregulated by miR-24. MiR-24 also regulates the cell cycle and is associated with numerous cancer hallmarks such as apoptosis, proliferation, metastasis, invasion, angiogenesis, autophagy, drug resistance and other diseases pathogenesis. Overall, miR-24 plays an emerging role in the diagnosis, prognosis and pathobiology of various diseases. MiR-24 is a potential target for targeted therapy in the era of precision medicine, which expands the landscape of targetable macromolecules, including undruggable proteins.

RNF6 Targeted by miR-26a-5p Protects Pancreatic β-Cell Function Against Type 2 Diabetes

BACKGROUND

Type 2 diabetes (T2D) is characterized by progressive β-cell dysfunction. Regulatory microRNAs (miRNAs) may be associated with this.

METHODS

Serum miR-26a-5p and RNF6 levels were detected in T2D patients and healthy volunteers via qRT-PCR. Subsequently, the role of specific dysregulated miR-26a-5p or RNF6 in regulating insulin content, cell proliferation, and apoptosis was studied in INS-1 cells. The targeting correlation between miR-26a-5p and RNF6 was detected using a luciferase assay.

RESULTS

RNF6 expression was significantly decreased in T2D individuals and INS-1 cells treated with high glucose, while miR-26a-5p expression was increased. In INS-1 cells, RNF6 overexpression or miR-26a-5p downregulation significantly increased insulin content and secretion, induced proliferation, and inhibited apoptosis. RNF6 has been identified as an miR-26a-5p target, which negatively regulates RNF6 to worsen INS-1 cell function.

CONCLUSION

RNF6 promoted insulin secretion and induced cell proliferation in INS-1 cells. This may be related to miR-26a-5p targeting and negatively regulating T2D pathogenesis.

Hypothalamic miR-1983 Targets Insulin Receptor β and the Insulin-mediated miR-1983 Increase Is Blocked by Metformin

MicroRNAs (miRNAs) expressed in the hypothalamus are capable of regulating energy balance and peripheral metabolism by inhibiting translation of target messenger RNAs (mRNAs). Hypothalamic insulin resistance is known to precede that in the periphery, thus a critical unanswered question is whether central insulin resistance creates a specific hypothalamic miRNA signature that can be identified and targeted. Here we show that miR-1983, a unique miRNA, is upregulated in vitro in 2 insulin-resistant immortalized hypothalamic neuronal neuropeptide Y-expressing models, and in vivo in hyperinsulinemic mice, with a concomitant decrease of insulin receptor β subunit protein, a target of miR-1983. Importantly, we demonstrate that miR-1983 is detectable in human blood serum and that its levels significantly correlate with blood insulin and the homeostatic model assessment of insulin resistance. Levels of miR-1983 are normalized with metformin exposure in mouse hypothalamic neuronal cell culture. Our findings provide evidence for miR-1983 as a unique biomarker of cellular insulin resistance, and a potential therapeutic target for prevention of human metabolic disease.

Construction of an HCC recurrence model based on the investigation of immune-related lncRNAs and related mechanisms

Long noncoding RNAs (lncRNAs) are emerging as critical regulators of gene expression and play fundamental roles in immune regulation. Growing evidence suggests that immune-related genes and lncRNAs can serve as markers to predict the prognosis of patients with cancers, including hepatocellular carcinoma (HCC). This study aimed to contract an immune-related lncRNA (IR-lncRNA) signature for prospective assessment to predict early recurrence of HCC. A total of 319 HCC samples under radical resection were randomly divided into a training cohort (161 samples) and a testing cohort (158 samples). In the training dataset, univariate, lasso, and multivariate Cox regression analyses identified a 9-IR-lncRNA signature closely related to disease-free survival. Kaplan-Meier analysis, principal component analysis, gene set enrichment analysis, and nomogram were used to evaluate the risk model. The results were further confirmed in the testing cohort. Furthermore, we constructed a competitive endogenous RNA regulatory network. The results of the present study indicated that this 9-IR-lncRNA signature has important clinical implications for improving predictive outcomes and guiding individualized treatment in HCC patients. These IR-lncRNAs and regulated genes may be potential biomarkers associated with the prognosis of HCC.

Relationship between elevated microRNAs and growth factors levels in the vitreous of patients with proliferative diabetic retinopathy

AIM

The aim of this study was to identify differentially expressed microRNAs (miRNAs) in the vitreous of patients with proliferative diabetic retinopathy (PDR) and correlate some of them with growth factors.

METHODS

Vitreous samples were collected from 5 PDR eyes and 5 control eyes, and then miRNAs were assayed with next-generation sequencing (NGS). Three differentially expressed miRNAs were validated in vitreous of another cohort using reverse transcriptase quantitative polymerase chain reaction (RT-qPCR).

RESULTS

Transforming growth factor β (TGF-β) and vascular endothelial growth factor (VEGF) signaling pathway were excavated out through bioinformatic analysis of deregulated miRNAs. The expression of hsa-miR-24-3p, hsa-miR-197-3p and hsa-miR-3184-3p, VEGF-A and TGF-β were confirmed to be significantly higher in the vitreous of PDR eyes than controls(P < 0.05). Furthermore, Pearson's correlation analysis showed significantly positive correlations between these elevated miRNAs and growth factors (P < 0.05).

CONCLUSIONS

Elevated vitreous levels of hsa-miR-24-3p, hsa-miR-197-3p, hsa-miR-3184-3p in PDR patients may play roles in pathophysiology of PDR, the target mRNAs of which significantly enriched in VEGF and TGF-β signaling pathways. Positive correlations between elevated vitreous levels of the three miRNAs and VEGF-A, TGF-β in PDR patients could provide a novel research direction for PDR.

MicroRNAs modulation and clinical outcomes at 1 year of follow-up in obese patients with pre-diabetes treated with metformin vs. placebo

BACKGROUNDS

Obese pre-diabetics over express cytokines that influence myocardial function via microRNAs (miRs) expression.

OBJECTIVES

To evaluate inflammatory/oxidative stress, miRs' expression and cardiovascular function in obese pre-diabetics assigned to metformin therapy vs. placebo vs. normo-glycemics at 12 months of follow-up.

MATERIALS AND METHODS

Eighty-three obese patients after abdominoplastic surgery were divided in pre-diabetics (n 55), normo-glycemics (n 28), and assigned to hypocaloric diet. Pre-diabetics were assigned to metformin (n 23) or to placebo (n 22) plus hypocaloric diet.

RESULTS

Obese pre-diabetics in metformin vs. placebo, and obese pre-diabetics with placebo vs. normoglycemics, had significant differences about IMT, MPI, and LVM (p < 0.05). Obese pre-diabetics in metformin vs. placebo showed significant reduction in serum miR-195 and miR-27 (p < 0.05). Obese pre-diabetics in metformin vs. normoglycemics showed higher expression of serum miR-195 and miR-27 (p < 0.05). Finally, we found inverse relation between IMT and insulin, HOMA-IR, miR-195, miR-27; between LVEF and Insulin, HOMA-IR, miR-195 and miR-27. We found inverse correlation between LVM and sirtuin-1, Insulin, HOMA-IR, miR-195 and miR-27, and direct correlation with interleukin-6. MPI inversely linked to miR-195 and miR-27.

CONCLUSIONS

In obese pre-diabetics', metformin significantly reduces inflammation/oxidative stress, and miR-195 and miR-27, with reduction in LVM, IMT.

Circulating microRNAs associated with prediabetes and geographic location in Latinos

BACKGROUND

Globally, type 2 diabetes is highly prevalent in individuals of Latino ancestry. The reasons underlying this high prevalence are not well understood, but both genetic and lifestyle factors are contributors. Circulating microRNAs are readily detectable in blood and are promising biomarkers to characterize biological responses (i.e., changes in gene expression) to lifestyle factors. Prior studies identified relationships between circulating microRNAs and risk for type 2 diabetes, but Latinos have largely been under-represented in these study samples.

AIMS/HYPOTHESIS

The aim of this study was to assess for differences in expression levels of three candidate microRNAs (miR-126, miR-146, miR-15) between individuals who had prediabetes compared to normal glycemic status and between individuals who self-identified with Latino ancestry in the United States (US) and native Mexicans living in or near Leon, Mexico.

METHODS

This was a cross-sectional study that included 45 Mexicans and 21 Latino participants from the US. Prediabetes was defined as fasting glucose 100-125 mg/dL or 2-h post-glucose challenge between 140 and 199 mg/dL. Expression levels of microRNAs from plasma were measured by qPCR. Linear and logistic regression models were used to assess relationships between individual microRNAs and glycemic status or geographic site.

RESULTS

None of the three microRNAs was associated with risk for type 2 diabetes. MiR-146a and miR-15 were significantly lower in the study sample from Mexico compared to the US. There was a significant interaction between miR-146a and BMI associated with fasting blood glucose.

CONCLUSIONS/INTERPRETATION

This study did not replicate in Latinos prior observations from other racial groups of associations between miR-126, miR-146a, and miR-15 and risk for type 2 diabetes. Future studies should consider other microRNAs related to different biological pathways as possible biomarkers for type 2 diabetes in Latinos.

Circulating microRNAs Signature for Predicting Response to GLP1-RA Therapy in Type 2 Diabetic Patients: A Pilot Study

Type 2 diabetes (T2D) represents one of the major health issues of this century. Despite the availability of an increasing number of anti-hyperglycemic drugs, a significant proportion of patients are inadequately controlled, thus highlighting the need for novel biomarkers to guide treatment selection. MicroRNAs (miRNAs) are small non-coding RNAs, proposed as useful diagnostic/prognostic markers. The aim of our study was to identify a miRNA signature occurring in responders to glucagon-like peptide 1 receptor agonists (GLP1-RA) therapy. We investigated the expression profile of eight T2D-associated circulating miRNAs in 26 prospectively evaluated diabetic patients in whom GLP1-RA was added to metformin. As expected, GLP1-RA treatment induced significant reductions of HbA1c and body weight, both after 6 and 12 months of therapy. Of note, baseline expression levels of the selected miRNAs revealed two distinct patient clusters: “high expressing” and “low expressing”. Interestingly, a significantly higher percentage of patients in the high expression group reached the glycemic target after 12 months of treatment. Our findings suggest that the evaluation of miRNA expression could be used to predict the likelihood of an early treatment response to GLP1-RA and to select patients in whom to start such treatment, paving the way to a personalized medicine approach.

Role of microRNA-129 in cancer and non-cancerous diseases (Review)

An increasing number of studies indicate that microRNAs (miRNAs/miRs) are involved in diverse biological signaling pathways and play important roles in the progression of various diseases, including both oncological and non-oncological diseases. These small non-coding RNAs can block translation, resulting in a low expression level of target genes. miR-129 is an miRNA that has been the focus of considerable research in recent years. A growing body of evidence shows that the miR-129 family not only functions in cancer, including osteosarcoma, nasopharyngeal carcinoma, and ovarian, prostate, lung, breast and colon cancer, but also in non-cancerous diseases, including heart failure (HF), epilepsy, Alzheimer's disease (AD), obesity, diabetes and intervertebral disc degeneration (IVDD). It is therefore necessary to summarize current research progress on the role of miR-129 in different diseases. The present review includes an updated summary of the mechanisms of the miR-129 family in oncological and non-oncological diseases. To the best of our knowledge, this is the first review focusing on the role of miR-129 in non-cancerous diseases such as obesity, HF, epilepsy, diabetes, IVDD and AD.

Integrated bioinformatics analysis reveals novel key biomarkers and potential candidate small molecule drugs in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is the metabolic disorder that appears during pregnancy. The current investigation aimed to identify central differentially expressed genes (DEGs) in GDM. The transcription profiling by array data (E-MTAB-6418) was obtained from the ArrayExpress database. The DEGs between GDM samples and non-GDM samples were analyzed. Functional enrichment analysis were performed using ToppGene. Then we constructed the protein–protein interaction (PPI) network of DEGs by the Search Tool for the Retrieval of Interacting Genes database (STRING) and module analysis was performed. Subsequently, we constructed the miRNA–hub gene network and TF–hub gene regulatory network. The validation of hub genes was performed through receiver operating characteristic curve (ROC). Finally, the candidate small molecules as potential drugs to treat GDM were predicted by using molecular docking. Through transcription profiling by array data, a total of 869 DEGs were detected including 439 up-regulated and 430 down-regulated genes. Functional enrichment analysis showed these DEGs were mainly enriched in reproduction, cell adhesion, cell surface interactions at the vascular wall and extracellular matrix organization. Ten genes, HSP90AA1, EGFR, RPS13, RBX1, PAK1, FYN, ABL1, SMAD3, STAT3 and PRKCA were associated with GDM, according to ROC analysis. Finally, the most significant small molecules were predicted based on molecular docking. This investigation identified hub genes, signal pathways and therapeutic agents, which might help us, enhance our understanding of the mechanisms of GDM and find some novel therapeutic agents for GDM.

Metformin and insulin-resistant related diseases: Emphasis on the role of microRNAs

Metformin is one of the most prescribed drugs in type II diabetes (T2DM) which has recently found new applications in the prevention and treatment of various illnesses, from metabolic disorders to cardiovascular and age-related diseases. Metformin improves insulin resistance (IR) by modulating metabolic mechanisms and mitochondrial biogenesis. Alternation of microRNAs (miRs) in the treatment of IR-related illnesses has been observed by metformin therapy. MiRs are small non-coding RNAs that play important roles in RNA silencing, targeting the 3'untranslated region (3'UTR) of most mRNAs and inhibiting the translation of related proteins. As a result, their dysregulation is associated with many diseases. Metformin may alter miRs levels in the treatment of various diseases by AMPK-dependent or AMPK-independent mechanisms. Here, we summarized the therapeutic role of metformin by modifying the aberrant expression of miRs as potential biomarkers or therapeutic targets in diseases in which IR plays a key role.

How metformin affects various malignancies by means of microRNAs: a brief review

Metformin known as the first-line orally prescribed drug for lowering blood glucose in type II diabetes (T2DM) has recently found various therapeutic applications including in cancer. Metformin has been studied for its influences in prevention and treatment of cancer through multiple mechanisms such as microRNA (miR) regulation. Alteration in the expression of miRs by metformin may play an important role in the treatment of various cancers. MiRs are single-stranded RNAs that are involved in gene regulation. By binding to the 3'UTR of target mRNAs, miRs influence protein levels. Irregularities in the expression of miRs that control the expression of oncogenes and tumor suppressor genes are associated with the onset and progression of cancer. Metformin may possess an effect on tumor prevention and progression by modifying miR expression and downstream pathways. Here, we summarize the effect of metformin on different types of cancer by regulating the expression of various miRs and the associated downstream molecules.

MicroRNAs, Parkinson's Disease, and Diabetes Mellitus

Parkinson’s disease (PD) is a neurodegenerative disorder that affects 1% of the population over the age of 60. Diabetes Mellitus (DM) is a metabolic disorder that affects approximately 25% of adults over the age of 60. Recent studies showed that DM increases the risk of developing PD. The link between DM and PD has been discussed in the literature in relation to different mechanisms including mitochondrial dysfunction, oxidative stress, and protein aggregation. In this paper, we review the common microRNA (miRNA) biomarkers of both diseases. miRNAs play an important role in cell differentiation, development, the regulation of the cell cycle, and apoptosis. They are also involved in the pathology of many diseases. miRNAs can mediate the insulin pathway and glucose absorption. miRNAs can also regulate PD-related genes. Therefore, exploring the common miRNA biomarkers of both PD and DM can shed a light on how these two diseases are correlated, and targeting miRNAs is a potential therapeutic opportunity for both diseases.

Extracellular vesicle-derived miR-26b-5p is up-regulated in the serum of patients with diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is a severe complication of diabetes; however, the pathogenesis of DR has not been completely clarified, which is mostly dependent on the molecular pathology. To investigate key serum-derived miRNAs associated with DR.

METHODS

miRNA expression profile arrays of human umbilical vein endothelial cells (HUVECs) treated with glucose were downloaded from the Gene Expression Omnibus (GEO) database (GSE74296). Weighted gene co-expression network analysis (WGCNA) was performed to obtain hub miRNAs, which were verified in HUVECs treated with 40 mM and 5 mM glucose, respectively. Meanwhile, serum samples of patients with DR and healthy controls were collected, and EVs were extracted from the patients' serum by ultracentrifugation. Hub miRNAs associated with endothelial dysfunction were verified in healthy individuals before and after treatment of patients with DR, by qRT-PCR.

RESULTS

These miRNAs were categorized into six modules, among which miR-26b-5p had a strong association with other modules. This miRNA was also one of the hyperglycemia-induced miRNAs related to endothelial dysfunction. miR-26b-5p was upregulated in HUVECs treated with 40 mM glucose and in the serum of patients with DR before and after treatment Furthermore, miR-26b-5p was slightly up-regulated in serum-derived EVs but not in serum without EVs in DM patients.

CONCLUSION

Our results suggest that EVs derived from miR-26b-5p are up-regulated in the serum of patients with DR.

Loss of miR-23b/27b/24-1 Cluster Impairs Glucose Tolerance via Glycolysis Pathway in Mice

Alterations in miRNAs are associated with many metabolic disorders, such as type 2 diabetes (T2DM). The miR-23b/27b/24-1 cluster contains miR-23b, miR-27b, and miR-24-1, which are located within 881 bp on chromosome 9. Studies examining the roles of miR-23b, miR-27b, and miR-24-1 have demonstrated their multifaceted functions in variable metabolic disorders. However, their joint roles in metabolism in vivo remain elusive. To investigate this subject, we constructed miR-23b/27b/24-1 cluster knockout (KO) mice. Compared with wild-type (WT) mice, the KO mice exhibited impaired glucose tolerance, which was accompanied by a reduction in the respiratory exchange rate (RER). These alterations were more noticeable after a high-fat diet (HFD) induction. Hepatic metabolomic results showed decreased expression of reduced nicotinamide adenine dinucleotide (NADH), nicotinamide adenine dinucleotide (NAD), phosphoenolpyruvic acid (PEP), and phosphoric acid, which are involved in the glycolysis pathway. The transcriptomic results indicated that genes involved in glycolysis showed a downregulation trend. qPCR and Western blot revealed that pyruvate kinase (PKLR), the key rate-limiting enzyme in glycolysis, was significantly reduced after the deletion of the miR-23b/27b/24-1 cluster. Together, these observations suggest that the miR-23b/27b/24-1 cluster is involved in the regulation of glucose homeostasis via the glycolysis pathway.

miR-378a-3p Participates in Metformin's Mechanism of Action on C2C12 Cells under Hyperglycemia

Metformin is the most used biguanide drug for the treatment of type 2 diabetes mellitus. Despite being mostly known for its hepatic anti-gluconeogenic effect, it is also known to modulate microRNAs (miRNAs, miRs) associated with metabolic diseases. The latter mechanism could be relevant for better understanding metformin’s mechanisms underlying its biological effects. In the current work, we found that metformin increases miR-378a-3p expression (p < 0.002) in C2C12 myoblasts previously exposed to hyperglycemic conditions. While the inhibition of miR-378a-3p was shown to impair metformin’s effect in ATP production, PEPCK activity and the expression of Tfam. Finally, mitophagy, an autophagic process responsible for the selective degradation of mitochondria, was found to be induced by miR-378a-3p (p < 0.04). miR-378a-3p stimulated mitophagy through a process independent of sestrin-2 (SESN2), a stress-responsible protein that has been recently demonstrated to positively modulate mitophagy. Our findings provide novel insights into an alternative mechanism of action of metformin involving miR-378a-3, which can be used in the future for the development of improved therapeutic strategies against metabolic diseases.

Evidence for Training-Induced Changes in miRNA Levels in the Skeletal Muscle of Patients With Type 2 Diabetes Mellitus

Physical training can improve glycemic control in patients with type 2 diabetes mellitus (T2DM). However, the underlying mechanisms are not entirely clear. An interesting piece of the puzzle could be the regulation of micro-RNAs (miRNAs). They are important modulators of protein expression. Some miRNAs were found to be both linked to poor glycemic control/insulin resistance (with evidence from in vivo and/or in vitro studies) and dysregulated in the skeletal muscle of T2DM patients. This pilot study examines whether a 3-month endurance training program [three times a week, 70-80% peak heart rate (HR_peak)] can down-regulate their levels in T2DM men (n = 7). One skeletal muscle biopsy sample was obtained from each patient at T1 (6 weeks pre-intervention), one at T2 (1 week pre-intervention) and one at T3 (3-4 days post-intervention). miRNA-27a-3p, -29a-3p, -29b-3p, -29c-3p, -106b-5p, -135a-5p, -143-3p, -144-3p, -194-5p, and - 206 levels were determined by RT-qPCR. Friedman ANOVA and post-hoc tests showed that miRNA-29b-3p, -29c-3p and -135a-5p levels were significantly reduced post-training (T3 vs. T2 and/or T1). Glycated hemoglobin (HbA1c) and HOMA insulin resistance index did not change significantly. However, HbA1c was reduced in 6 of 7 patients post-training. Furthermore, Spearman's rank correlation analyses with all values from all time points showed significant negative associations between miRNA-29c-3p, -106b-5p, -144-3p and -194-5p levels and cardiorespiratory fitness (VO_2peak). The study results imply that regular exercise and improving one's physical fitness is helpful for the regulation of skeletal muscle miRNAs in T2DM patients. Whether or not changes in the miRNA profile can affect the clinical situation of T2DM patients warrants further research.