Metformin-mediated epigenetic modifications in diabetes and associated conditions: Biological and clinical relevance

Metformin alleviates cadmium-induced reproductive toxicity by enhancing mitochondrial biosynthesis and epigenetic modifications in female mice

Cadmium, a pervasive environmental pollutant, exerts detrimental effects on various tissues and cells, particularly targeting the reproductive system, thereby posing significant risks to both animal food safety and human health. Despite its widespread impact, research on substances capable of mitigating cadmium-induced reproductive toxicity remains scarce, especially concerning female reproductive health. Metformin, a widely used oral antihyperglycemic drug, has demonstrated a range of beneficial effects, including anti-aging and antioxidant properties. This study aims to investigate the potential and underlying mechanisms of metformin in alleviating cadmium-induced reproductive toxicity in females. Over a period of 35 consecutive days, mice were exposed to cadmium-contaminated water (32 mg/l) and orally administered 10 mg metformin dissolved in 0.2 ml normal saline. Our findings reveal that metformin effectively mitigates cadmium-induced disruptions in the estrous cycle, follicular development, and oocyte meiotic maturation. Specifically, metformin enhances ATP production in oocytes by boosting mitochondrial mass and biosynthesis, thereby counteracting cadmium-induced oxidative stress and spindle morphology defects during meiosis. Additionally, metformin restores the DNA repair capacity of oocytes, alleviating cadmium-induced DNA damage. This restorative effect is partially mediated by metformin's ability to improve key epigenetic modifications, such as histone acetylation, histone methylation, and DNA methylation in oocytes. These results underscore metformin's potential as a protective or therapeutic agent against cadmium reproductive toxicity, primarily by maintaining cellular homeostasis to bolster oocyte resilience against cadmium toxicity and preserving normal epigenetic modifications to ensure oocyte quality.

Nexus of NFκB/VEGF/MMP9 signaling in diabetic retinopathy-linked dementia: Management by phenolic acid-enabled nanotherapeutics

AIMS

The purpose of this review is to highlight the therapeutic effectiveness of phenolic acids in slowing the progression of diabetic retinopathy (DR)-linked dementia by addressing the nuclear factor kappa B (NFκB)/matrix metalloproteinase-9 (MMP9)/vascular endothelial growth factor (VEGF) interconnected pathway.

MATERIALS AND METHODS

We searched 80 papers published in the last 20 years using terms like DR, dementia, phenolic acids, NFkB/VEFG/MMP9 signaling, and microRNAs (miRs) in databases including Pub-Med, WOS, and Google Scholar. By encasing phenolic acid in nanoparticles and then controlling its release into the targeted tissues, nanotherapeutics can increase their effectiveness. Results were summarized, and compared, and research gaps were identified throughout the data collection and interpretation.

KEY FINDINGS

Amyloid beta (Aβ) deposition in neuronal cells and drusen sites of the eye leads to the activation of NFkB/VEGF/MMP9 signaling and microRNAs (miR146a and miR155), which in turn energizes the accumulation of pro-inflammatory and pro-angiogenic microenvironments in the brain and retina leading to DR-linked dementia. This study demonstrates the potential of phenolic acid-enabled nanotherapeutics as a functional food or supplement for preventing and treating DR-linked dementia, and oxidative stress-related diseases.

SIGNIFICANCE

The retina has mechanisms to clear metabolic waste including Aβ, but the activation of NFkB/ MMP9/ VEGF signaling leads to fatal pathological consequences. Understanding the role of miR146a and miR155 provides potential therapeutic avenues for managing the complex pathology shared between DR and dementia. In particular, phenolic acid nanotherapeutics offer a dual benefit in retinal regeneration and dementia management.

Diverse Applications of the Anti-Diabetic Drug Metformin in Treating Human Disease

Metformin is a commonly used drug for treating type 2 diabetes. Metformin is an inexpensive drug with low/no side effects and is well tolerated in human patients of different ages. Recent therapeutic strategies for human disease have considered the benefits of drug repurposing. This includes the use of the anti-diabetic drug metformin. Accordingly, the anti-inflammatory, anti-cancer, anti-viral, neuroprotective, and cardioprotective potentials of metformin have deemed it a suitable candidate for treating a plethora of human diseases. As results from preclinical studies using cellular and animal model systems appear promising, clinical trials with metformin in the context of non-diabetes-related illnesses have been started. Here, we aim to provide a comprehensive overview of the therapeutic potential of metformin in different animal models of human disease and its suggested relationship to epigenetics and ailments with epigenetic components.

Treatment of Diabetes in Pregnancy With Metformin

Metformin is a commonly used drug in the treatment of type 2 diabetes and has been used to treat gestational diabetes since the 1970s. In pregnancy, its proven benefits include reduced gestational weight gain and reduced fetal size; some studies have shown reduced risk of cesarean delivery and lower rates of hypertension. Metformin can reduce the need for insulin therapy but does not eliminate such need in many patients. Despite these benefits, metformin crosses the placenta and has been associated with increases in the risk of giving birth to small-for-gestational-age neonates in some studies of individuals with type 2 diabetes in pregnancy. In addition, higher body mass index (BMI) z-scores have been observed among exposed offspring in some of the long-term follow-up studies. Nevertheless, metformin's low cost, ease of administration, and global reach make it a reasonable intervention in a population affected by rising rates of obesity and diabetes in pregnancy. Further follow-up studies are required to monitor the long-term health of exposed offspring.

Epigenetic mechanisms in cardiovascular complications of diabetes: towards future therapies

The pathophysiological mechanisms of cardiovascular disease and microvascular complications in diabetes have been extensively studied, but effective methods of prevention and treatment are still lacking. In recent years, DNA methylation, histone modifications, and non-coding RNAs have arisen as possible mechanisms involved in the development, maintenance, and progression of micro- and macro-vascular complications of diabetes. Epigenetic changes have the characteristic of being heritable or deletable. For this reason, they are now being studied as a therapeutic target for the treatment of diabetes and the prevention or for slowing down its complications, aiming to alleviate the personal and social burden of the disease.This review addresses current knowledge of the pathophysiological links between diabetes and cardiovascular complications, focusing on the role of epigenetic modifications, including DNA methylation and histone modifications. In addition, although the treatment of complications of diabetes with "epidrugs" is still far from being a reality and faces several challenges, we present the most promising molecules and approaches in this field.

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.

microRNA 21 and long non-coding RNAs interplays underlie cancer pathophysiology: A narrative review

Non-coding RNAs (ncRNAs) are a diverse group of functional RNA molecules that lack the ability to code for proteins. Despite missing this traditional role, ncRNAs have emerged as crucial regulators of various biological processes and have been implicated in the development and progression of many diseases, including cancer. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are two prominent classes of ncRNAs that have emerged as key players in cancer pathophysiology. In particular, miR-21 has been reported to exhibit oncogenic roles in various forms of human cancer, including prostate, breast, lung, and colorectal cancer. In this context, miR-21 overexpression is closely associated with tumor proliferation, growth, invasion, angiogenesis, and chemoresistance, whereas miR-21 inactivation is linked to the regression of most tumor-related processes. Accordingly, miR-21 is a crucial modulator of various canonical oncogenic pathways such as PTEN/PI3K/Akt, Wnt/β-catenin, STAT, p53, MMP2, and MMP9. Moreover, interplays between lncRNA and miRNA further complicate the regulatory mechanisms underlying tumor development and progression. In this regard, several lncRNAs have been found to interact with miR-21 and, by functioning as competitive endogenous RNAs (ceRNAs) or miRNA sponges, can modulate cancer tumorigenesis. This work presents and discusses recent findings highlighting the roles and pathophysiological implications of the miR-21-lncRNA regulatory axis in cancer occurrence, development, and progression. The data collected indicate that specific lncRNAs, such as MEG3, CASC2, and GAS5, are strongly associated with miR-21 in various types of cancer, including gastric, cervical, lung, and glioma. Indeed, these lncRNAs are well-known tumor suppressors and are commonly downregulated in different types of tumors. Conversely, by modulating various mechanisms and oncogenic signaling pathways, their overexpression has been linked with preventing tumor formation and development. This review highlights the significance of these regulatory pathways in cancer and their potential for use in cancer therapy as diagnostic and prognostic markers.

Effects of Metformin on CIMT and FMD in PCOS patients: a systematic review and meta-analysis

BACKGROUND

This study aims to analyze the efficacy of metformin on carotid intima media thickness (CIMT) and flow-mediated dilation (FMD) for patients with polycystic ovary syndrome (PCOS).

METHODS

A literature search of PubMed, Embase, and the Cochrane Library from inception to December 2023 was conducted. Then, after studies selection and data extraction, the mean difference (MD) with a 95% confidence interval (CI) was used to evaluate metformin efficacy in CIMT and FMD for PCOS patients. Heterogeneity was investigated through subgroup and sensitivity analysis. The protocol of our study has been registered in PROSPERO (CRD42024497239).

RESULTS

A total of 12 studies with 248 patients were included. CIMT was lower in the endpoint group (after metformin) compared with the baseline group (before metformin) (MD = -0.11, 95% CI = -0.21 to -0.01, p = 0.04). FMD was higher in the endpoint group compared with the baseline group (MD = 3.25, 95% CI = 1.85 to 4.66, p < 0.01). No statistically significant difference was observed in nitroglycerin-mediated dilation (NMD) between the two groups (MD = 0.65, p = 0.51). Subgroup analysis showed that a relatively lower MD of CIMT in PCOS patients from Europe in the endpoint group compared with the baseline group (MD = -0.09, 95% CI = -0.14 to -0.04, p < 0.001). However, the MD in CIMT was not significantly different between the endpoint group and baseline group in PCOS patients from Asia (p = 0.270).

CONCLUSION

Metformin may have a beneficial effect on CIMT and FMD, but not on NMD, suggesting that metformin may help reduce cardiovascular events in PCOS patients. Notably, the clinical efficacy of metformin can be influenced by regional differences and study types.

A Series of Biguanide Ligands and Their Cu(II) Complexes: Cholinesterase Inhibitory and Antimicrobial Properties

In this work, a series of biguanide hydrochloride salts and their Cu(II) complexes were synthesized and screened for their acetyl/butyryl choline esterase inhibitory and antimicrobial properties. The structures of the synthesized compounds were characterised by common spectroscopic and analytical methods. Biguanide compounds showed considerably lower inhibitory activity compared to the reference drugs donepezil and galantamine. On the other hand, complexation of the biguanide compounds with Cu(II) resulted in dramatic increase in the inhibitory activity. The Cu(II) complexes showed AChE inhibitory activity with the IC50 values of 21.29±0.95-82.53±0.20 μM and those values are comparable to that of donepezil (IC50 : 18.54±1.03 μM). The synthesised compounds were also screened for their antimicrobial activity towards gram positive (+) and gram negative (-) bacteria. Compounds (12.50 mg/mL) showed important antibacterial properties with inhibition zones of 8-28 mm diameter against gram-positive and gram-negative microorganisms. Compounds A03 and A08 exhibited more antimicrobial properties towards E. coli than standard antibiotics amikacin and gentamicin.