Target Of Metformin Research Articles

BRAF Controls the Effects of Metformin on Neuroblast Cell Divisions in C. elegans.

Metformin has demonstrated substantial potential for use in cancer treatments. Liver kinase B (LKB)-AMP-activated protein kinase (AMPK) and mTOR are reported to be the main targets of metformin in relation to its ability to prevent cancer cell proliferation. However, the role of metformin in the control of neoplastic cancer cell growth is possibly independent of LKB-AMPK and mTOR. Using C. elegans as a model, we found that the neuronal Q-cell divisions in L1-arrested worms were suppressed following metformin treatment in AMPK-deficient mutants, suggesting that the mechanism by which metformin suppresses these cell divisions is independent of AMPK. Our results showed that the mTOR pathway indeed played a role in controlling germ cell proliferation, but it was not involved in the neuronal Q-cell divisions occurring in L1-arrested worms. We found that the neuronal Q-cells divisions were held at G1/S cell stage by metformin in vivo. Additionally, we demonstrated that metformin could reduce the phosphorylation activity of BRAF and block the BRAF-MAPK oncogenesis pathway to regulate neuronal Q-cell divisions during L1 arrest. This work discloses a new mechanism by which metformin treatment acts to promote neuronal cancer prevention, and these results will help promote the study of the anticancer mechanisms underlying metformin treatments.

A Molecular Perspective on the Potential Benefits of Metformin for the Treatment of Inflammatory Skin Disorders.

Due to its anti-hyperglycemic effect, metformin is the first-line medication for the treatment of type 2 diabetes, particularly in people who are obese. However, metformin is a drug with a very wide range of pharmacological properties and reports of its therapeutic effect on diseases including inflammation and cancer are increasing. Numerous research groups have reported that metformin has beneficial effects on a variety of inflammatory skin disorders including psoriasis, acanthosis nigricans, acne, hidradenitis suppurativa, and allergic contact dermatitis. According to these reports, in addition to the well-known action of metformin, that is, its anti-hyperglycemic effect, NF-kB inhibition and the resulting alteration to the cytokine network may be the potential targets of metformin. Its anti-hyperandrogenism effect has also been confirmed as the major action of metformin in some inflammatory skin diseases. Moreover, novel regulatory mechanisms, including autophagy and antioxidant processes, have been suggested as promising mechanisms of action for metformin in inflammatory skin disorders.

Metformin alleviates high glucose-induced ER stress and inflammation by inhibiting the interaction between caveolin1 and AMPKα in rat astrocytes

Hyperglycemia-induced endoplasmic reticulum (ER) stress and inflammatory response afflict neuropathological diseases (such as epilepsy and Alzheimer’s disease). Astrocytes are the critical cells that mediate brain inflammation in this process. Metformin is a kind of hypoglycemic drugs widely used in clinical practice, which has anti-inflammatory and antioxidant effects. However, the biological mechanism of metformin in regulating inflammation and ER stress induced by hyperglycemia remains unclear. Therefore, in this study, rat primary astrocytes were preincubated with metformin and AMPK agonist AICAR for 1 h prior to administration of high glucose (33 mM glucose). Our findings indicated that metformin treatment inhibited the elevated ER stress and inflammation in high glucose-treated astrocytes. Moreover, metformin inhibited the formation of caveolin1/AMPKα complex. Additionally, the effects of AICAR on astrocytes were similar to metformin. In conclusion, metformin reduced high glucose-induced ER stress and inflammation by inhibiting the interaction between caveolin1 and AMPKα, suggesting that the caveolin1/AMPKα complex may be a potential therapeutic target for metformin.

Molecular mechanisms underlining the role of metformin as a therapeutic agent in lung cancer.

Metformin, a first-line therapeutic for type 2 diabetes, has been studied for its potential use in cancer treatment following a number of epidemiological studies that have demonstrated reduced cancer incidence and mortality rates among patients treated with the drug. As yet, however, there remains significant uncertainty about the molecular mechanisms by which metformin exerts its anti-cancer effects. Herein, we summarize the evidence surrounding the anti-lung cancer effects of metformin. Specifically, we explore protein targets of metformin, including AMPK, PP2A, IRF-1/YAP and HGF and we outline the proposed mechanisms of action for metformin in lung cancer, with particular attention given to apoptosis and autophagy. We also closely examine the synergistic activity of metformin with existing cancer treatment regimens, such as TKI's, platinum-based agents and immune therapeutics. In addition to considering preclinical and clinical studies, we also dissect and contextualize the limitations and inconsistencies of the current literature, especially those of epidemiological studies. Finally, we offer a potential trajectory for future research in this rapidly evolving area of basic and clinical oncology.

19P Deep eutectic solvent mixture formed from 2-deoxy-D-glucose and metformin targets cancer cell metabolism and induces apoptosis in breast cancer cell line xenografts

19P Deep eutectic solvent mixture formed from 2-deoxy-D-glucose and metformin targets cancer cell metabolism and induces apoptosis in breast cancer cell line xenografts

Evaluating the impact of AMPK activation, a target of metformin, on risk of cardiovascular diseases and cancer in the UK Biobank: a Mendelian randomisation study.

Whether metformin reduces cardiovascular or cancer risk is unclear owing to concerns over immortal time bias and confounding in observational studies. This study evaluated the effect of AMP-activated protein kinase (AMPK), the target of metformin, on risk of cardiovascular disease and cancer. This is a Mendelian randomisation design, using AMPK, the pharmacological target of metformin, to infer the AMPK pathway-dependent effects of metformin on risk of cardiovascular disease and cancer in participants of white British ancestry in the UK Biobank. A total of 391,199 participants were included (mean age 56.9years; 54.1% women), including 26,690 cases of type 2 diabetes, 38,098 cases of coronary artery disease and 80,941 cases of overall cancer. Genetically predicted reduction in HbA1c (%) instrumented by AMPK variants was associated with a 61% reduction in risk of type 2 diabetes (OR 0.39; 95% CI 0.20, 0.78; p = 7.69 × 10-3), a 53% decrease in the risk of coronary artery disease (OR 0.47; 95% CI 0.26, 0.84; p = 0.01) and a 44% decrease in the risk of overall cancer (OR 0.56; 95% CI 0.36, 0.85; p = 7.23 × 10-3). Results were similar using median or quartiles of AMPK score, with dose-response effects (p for trend = 4.18 × 10-3 for type 2 diabetes, 4.37 × 10-3 for coronary artery disease and 4.04 × 10-3 for overall cancer). This study provides some genetic evidence that AMPK activation by metformin may protect against cardiovascular disease and cancer, which needs to be confirmed by randomised controlled trials.

Differential effects of metformin on reductive activity and energy production in pituitary tumor cells compared to myogenic precursors.

Given the multiple targets of metformin within cells, the mechanism by which it may exert a growth-inhibitory action on pituitary tumor cells in vitro remains to be explored. Previous research stressed metformin-induced changes in the activity of signaling pathways regulating cell growth and cell death. In this work, we investigated the effects of metformin on cell viability markers related to cell metabolic activity in rat pituitary tumor cells versus rat myogenic precursors as a model of normal proliferating somatic cells. We designed our experiments in order to use the MTT reduction as a marker of cellular reductive activity and the total cellular ATP levels as a marker of energy supply during short incubations with different metabolic substrates (sodium pyruvate, D-glucose, L-glutamine, sodium citrate). Then, we extended the analysis to extracellular glucose consumption, extracellular medium acidification and pyruvate dehydrogenase (PDH) complex activity. Metformin was found to be effective in both cell types at the same concentrations, although the outcome of the treatment was quite the opposite. Unexpectedly, metformin increased the viability of subconfluent rat myoblasts. Rat pituitary tumor cells and myoblasts differed in the utilization of distinct metabolic substrates and the PDH complex activity. Metformin actions on reductive activity and ATP production were substrate-dependent. Overall, this work points out that metformin actions at the cellular level depend on metabolic features and metabolic requirements of cells. The pyruvate metabolic branch point is most likely to play a main role in the variability of cell response to metformin.

Blood-Based Biomarkers Predictive of Metformin Target Engagement in Fragile X Syndrome.

Recent advances in neurobiology have provided several molecular entrees for targeted treatments for Fragile X syndrome (FXS). However, the efficacy of these treatments has been demonstrated mainly in animal models and has not been consistently predictive of targeted drugs’ response in the preponderance of human clinical trials. Because of the heterogeneity of FXS at various levels, including the molecular level, phenotypic manifestation, and drug response, it is critically important to identify biomarkers that can help in patient stratification and prediction of therapeutic efficacy. The primary objective of this study was to assess the ability of molecular biomarkers to predict phenotypic subgroups, symptom severity, and treatment response to metformin in clinically treated patients with FXS. We specifically tested a triplex protein array comprising of hexokinase 1 (HK1), RAS (all isoforms), and Matrix Metalloproteinase 9 (MMP9) that we previously demonstrated were dysregulated in the FXS mouse model and in blood samples from patient with FXS. Seventeen participants with FXS, 12 males and 5 females, treated clinically with metformin were included in this study. The disruption in expression abundance of these proteins was normalized and associated with significant self-reported improvement in clinical phenotypes (CGI-I in addition to BMI) in a subset of participants with FXS. Our preliminary findings suggest that these proteins are of strong molecular relevance to the FXS pathology that could make them useful molecular biomarkers for this syndrome.

Therapeutic role of metformin and troglitazone to prevent cancer risk in diabetic patients: evidences from experimental studies

Abstract Objectives It is evident from literature that individual with diabetes mellitus is more prone to develop cancer as compared to non-diabetic one. We aimed to highlight the risk factors that trigger the tumor formation in diabetic individuals and collect evidences regarding the preventive role of anti-diabetics in cancer. Content A comprehensive literature was searched in English language using electronic databases including PubMed, ScienceDirect, Medline, Scopus and Embase. Summary and outlook Antidiabetic drugs notably metformin and troglitazone, exhibit anticancer effects. Metformin targets energy sensor pathway i. e., AMPK/mTOR which is controlled by LKB1. Whereas. troglitazone activates PPARϒ that modulate the transcription of insulin responsive gene which is essential for lipid and glucose metabolism. Adipocytes are highly expressed with PPARɣ which induce differentiation and regulate adipogenesis. Ligand-driven expression of PPARɣ in myoblast and fibroblast cell lines produces adipocyte differentiation in breast cancer. Prostate cancer that expresses PPARɣ may be suppressed by troglitazone and retinoid which inhibit their proliferation and initiate differentiation. The findings summarized here show that metformin and troglitazone may have the ability to inhibit the cancer cell proliferation via involvement of molecular pathways. This therapeutic intervention will help to control the progression of cancer in diabetic patients.

Metformin Biodistribution: A Key to Mechanisms of Action?

Metformin has undisputed glucose-lowering effects in diabetes and an impressive safety record. It has also shown promising effects beyond diabetes, and several hundred clinical trials involving metformin are currently planned or active. Metformin targets intracellular effectors, but exactly which remain to be established, and in an era of precision medicine, an incomplete understanding of mechanisms of action may limit the use of metformin. Distribution of metformin depends on specific organic cation transporter proteins that are organ- and species-specific. Therefore, target tissues of metformin can be identified by cellular uptake of the drug, and exploring the biodistribution of the drug in humans becomes an attractive strategy to assist the many investigations into the mechanisms of action of metformin performed in animals. In this review, we combine the emerging evidence from the use of 11C-labeled metformin in humans to discuss metformin action in liver, intestines, and kidney, which are the organs with the most avid uptake of the drug.

The Hepatic Plasma Membrane Citrate Transporter NaCT (SLC13A5) as a Molecular Target for Metformin

Metformin is the first-line treatment for type 2 diabetes. Inhibition of hepatic gluconeogenesis is the primary contributor to its anti-diabetic effect. Metformin inhibits complex I and α-glycerophosphate shuttle, and the resultant increase in cytoplasmic NADH/NAD+ ratio diverts glucose precursors away from gluconeogenesis. These actions depend on metformin-mediated activation of AMP kinase (AMPK). Here we report on a hitherto unknown mechanism. Metformin inhibits the expression of the plasma membrane citrate transporter NaCT in HepG2 cells and decreases cellular levels of citrate. 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR), an AMPK activator, elicits a similar effect. The process involves a decrease in maximal velocity with no change in substrate affinity. The decrease in NaCT expression is associated with decreased mRNA levels. AMPK inhibits mTOR, and the mTOR inhibitor rapamycin also decreases NaCT expression. The transcription factor downstream of AMPK that is relevant to cAMP signaling is CREB; decreased levels of phospho-CREB seem to mediate the observed effects of metformin on NaCT. Citrate is known to suppress glycolysis by inhibiting phosphofructokinase-1 and activate gluconeogenesis by stimulating fructose-1,6-bisphophatase; therefore, the decrease in cellular levels of citrate would stimulate glycolysis and inhibit gluconeogenesis. These studies uncover a novel mechanism for the anti-diabetic actions of metformin.

Novel Targets of Metformin in Cardioprotection: Beyond the Effects Mediated by AMPK.

Ischemic heart disease is the main cause of death globally. In the heart, the ischemia/reperfusion injury gives rise to a complex cascade of molecular signals, called cardiac remodeling, which generates harmful consequences for the contractile function of the myocardium and consequently heart failure. Metformin is the drug of choice in the treatment of type 2 diabetes mellitus. Clinical data suggest the direct effects of this drug on cardiac metabolism and studies in animal models showed that metformin activates the classical pathway of AMP-activated protein kinase (AMPK), generating cardioprotective effects during cardiac remodeling, hypertrophy and fibrosis. Furthermore, new studies have emerged about other targets of metformin with a potential role in cardioprotection. This state of the art review shows the available scientific evidence of the cardioprotective potential of metformin and its possible effects beyond AMPK. Targeting of autophagy, mitochondrial function and miRNAs are also explored as cardioprotective approaches along with a therapeutic potential. Further advances related to the biological effects of metformin and cardioprotective approaches may provide new therapies to protect the heart and prevent cardiac remodeling and heart failure.

Metformin is distributed to tumor tissue in breast cancer patients in vivo: A 11C-metformin PET/CT study.

Epidemiological studies and randomized clinical trials suggest that the antidiabetic drug, metformin, may have anti-neoplastic effects. The mechanism that mediates these beneficial effects has been suggested to involve direct action on cancer cells, but this will require distribution of metformin in tumor tissue. The present study was designed to investigate metformin distribution in vivo in breast and liver tissue in breast cancer patients. Seven patients recently diagnosed with ductal carcinoma were recruited. Using PET/CT, tissue distribution of metformin was determined in vivo for 90min after injection of a carbon-11-labeled metformin tracer. After surgery, tumor tissue was investigated for gene expression levels of metformin transporter proteins. Tumor tissue displayed a distinct uptake of metformin compared to normal breast tissue AUC0-90min (75.4 ± 5.5 vs 42.3 ± 6.3) g/ml*min (p = 0.01). Maximal concentration in tumor was at 1min where it reached approximately 30% of the activity in the liver. The metformin transporter protein with the highest gene expression in tumor tissue was multidrug and toxin extrusion 1 (MATE 1) followed by plasma membrane monoamine transporter (PMAT). This study confirms that metformin is transported into tumor tissue in women with breast cancer. This finding support that metformin may have direct anti-neoplastic effects on tumor cells in breast cancer patients. However, distribution of metformin in tumor tissue is markedly lower than in liver, an established metformin target tissue.

Metformin inhibition of colorectal cancer cell migration is associated with rebuilt adherens junctions and FAK downregulation.

E-cadherin, a central component of the adherens junction (AJ), is a single-pass transmembrane protein that mediates cell-cell adhesion. The loss of E-cadherin surface expression, and therefore cell-cell adhesion, leads to increased cell migration and invasion. Treatment of colorectal cancer (CRC)-derived cells (SW-480 and HT-29) with 2.0 mM metformin promoted a redistribution of cytosolic E-cadherin to de novo formed puncta along the length of the contacting membranes of these cells. Metformin also promoted translocation from the cytosol to the plasma membrane of p120-catenin, another core component of the AJs. Furthermore, E-cadherin and p120-catenin colocalized with β-catenin at cell-cell contacts. Western blot analysis of lysates of CRC-derived cells revealed a substantial metformin-induced increase in the level of p120-catenin as well as E-cadherin phosphorylation on Ser838/840 , a modification associated with β-catenin/E-cadherin interaction. These modifications in E-cadherin, p120-catenin and β-catenin localization suggest that metformin induces rebuilding of AJs in CRC-derived cells. Those modifications were accompanied by the inhibition of focal adhesion kinase (FAK), as revealed by a significant decrease in the phosphorylation of FAK at Tyr397 and paxillin at Tyr118 . These changes were associated with a reduction in the numbers, but an increase in the size, of focal adhesions and by the inhibition of cell migration. Overall, these observations indicate that metformin targets multiple pathways associated with CRC development and progression.

Metformin up-regulated miR-107 expression and enhanced the inhibitory effect of miR-107 on gastric cancer growth.

Gastric cancer (GC) is one of the most common malignant neoplasms and is the third leading cause of cancer-related death around the world. Metformin has been well reported to have an inhibitory effect on the growth of various cancers by regulating the expression of microRNAs (miRNAs). However, the specific miRNA(s) regulated by metformin in GC have not been identified. In this study, real-time reverse transcription polymerase chain reaction (RT-PCR) analysis in vitro indicated that miR-107 expression was up-regulated in metformin-treated SGC-7901 cells compared with untreated SGC-7901 and MGC803 cells. Amplification of miR-107 expression further reduced cell proliferation in metformin-treated GC cells. A bioinformatics analysis showed that mitogen-activated protein kinase 8 (MAPK8) was the common target of metformin and miR-107. MAPK8 expression is associated with immune cell infiltration in GC as well as overall GC patient survival. Our study demonstrates that miR-107 enhances the anti-cancer effects of metformin in GC tissues, which offers a novel strategy for the treatment of GC.

Why the endothelium? The endothelium as a target to reduce diabetes-associated vascular disease.

Over the past 66 years, our knowledge of the role of the endothelium in the regulation of cardiovascular function and dysfunction has advanced from the assumption that it is a single layer of cells that serves as a barrier between the blood stream and vascular smooth muscle to an understanding of its role as an essential endocrine-like organ. In terms of historical contributions, we pay particular credit to (1) the Canadian scientist Dr. Rudolf Altschul who, based on pathological changes in the appearance of the endothelium, advanced the argument in 1954 that "one is only as old as one's endothelium" and (2) the American scientist Dr. Robert Furchgott, a 1998 Nobel Prize winner in Physiology or Medicine, who identified the importance of the endothelium in the regulation of blood flow. This review provides a brief history of how our knowledge of endothelial function has advanced and now recognize that the endothelium produces a plethora of signaling molecules possessing paracrine, autocrine, and, arguably, systemic hormone functions. In addition, the endothelium is a therapeutic target for the anti-diabetic drugs metformin, glucagon-like peptide I (GLP-1) receptor agonists, and inhibitors of the sodium-glucose cotransporter 2 (SGLT2) that offset the vascular disease associated with diabetes.

Transcriptomic analysis of human primary breast cancer identifies fatty acid oxidation as a target for metformin

BackgroundEpidemiological studies suggest that metformin may reduce the incidence of cancer in patients with diabetes and multiple late phase clinical trials assessing the potential of repurposing this drug are underway. Transcriptomic profiling of tumour samples is an excellent tool to understand drug bioactivity, identify candidate biomarkers and assess for mechanisms of resistance to therapy.MethodsThirty-six patients with untreated primary breast cancer were recruited to a window study and transcriptomic profiling of tumour samples carried out before and after metformin treatment.ResultsMultiple genes that regulate fatty acid oxidation were upregulated at the transcriptomic level and there was a differential change in expression between two previously identified cohorts of patients with distinct metabolic responses. Increase in expression of a mitochondrial fatty oxidation gene composite signature correlated with change in a proliferation gene signature. In vitro assays showed that, in contrast to previous studies in models of normal cells, metformin reduces fatty acid oxidation with a subsequent accumulation of intracellular triglyceride, independent of AMPK activation.ConclusionsWe propose that metformin at clinical doses targets fatty acid oxidation in cancer cells with implications for patient selection and drug combinations.Clinical Trial RegistrationNCT01266486.

Hypoxia and hyperglycaemia determine why some endometrial tumours fail to respond to metformin

BackgroundHigh expression of Ki67, a proliferation marker, is associated with reduced endometrial cancer-specific survival. Pre-surgical metformin reduces tumour Ki-67 expression in some women with endometrial cancer. Metformin’s anti-cancer activity may relate to effects on cellular energy metabolism. Since tumour hypoxia and glucose availability are major cellular redox determinants, we evaluated their role in endometrial cancer response to metformin.MethodsEndometrial cancer biopsies from women treated with pre-surgical metformin were tested for the hypoxia markers, HIF-1α and CA-9. Endometrial cancer cell lines were treated with metformin in variable glucose concentrations in normoxia or hypoxia and cell viability, mitochondrial biogenesis, function and energy metabolism were assessed.ResultsIn women treated with metformin (n = 28), Ki-67 response was lower in hypoxic tumours. Metformin showed minimal cytostatic effects towards Ishikawa and HEC1A cells in conventional medium (25 mM glucose). In low glucose (5.5 mM), a dose-dependent cytostatic effect was observed in normoxia but attenuated in hypoxia. Tumours treated with metformin showed increased mitochondrial mass (n = 25), while in cultured cells metformin decreased mitochondrial function. Metformin targets mitochondrial respiration, however, in hypoxic, high glucose conditions, there was a switch to glycolytic metabolism and decreased metformin response.ConclusionsUnderstanding the metabolic adaptations of endometrial tumours may identify patients likely to derive clinical benefit from metformin.

Effects of metformin on metabolism of white and brown adipose tissue in obese C57BL/6J mice

BackgroundTo investigate effects of metformin on the regulation of proteins of white adipose tissue (WAT) and brown adipose tissue (BAT) in obesity and explore the underlying mechanisms on energy metabolism.MethodsC57BL/6J mice were fed with normal diet (ND, n = 6) or high-fat diet (HFD, n = 12) for 22 weeks. HFD-induced obese mice were treated with metformin (MET, n = 6). After treatment for 8 weeks, oral glucose tolerance test (OGTT) and hyperinsulinemic–euglycemic clamp were performed to evaluate the improvement of glucose tolerance and insulin sensitivity. Protein expressions of WAT and BAT in mice among ND, HFD, and MET group were identified and quantified with isobaric tag for relative and absolute quantification (iTRAQ) coupled with 2D LC–MS/MS. The results were analyzed by MASCOT, Scaffold and IPA.ResultsThe glucose infusion rate in MET group was increased significantly compared with HFD group. We identified 4388 and 3486 proteins in WAT and BAT, respectively. As compared MET to HFD, differential expressed proteins in WAT and BAT were mainly assigned to the pathways of EIF2 signaling and mitochondrial dysfunction, respectively. In the pathways, CPT1a in WAT, CPT1b and CPT2 in BAT were down-regulated by metformin significantly.ConclusionsMetformin improved the body weight and insulin sensitivity of obese mice. Meanwhile, metformin might ameliorate endoplasmic reticulum stress in WAT, and affect fatty acid metabolism in WAT and BAT. CPT1 might be a potential target of metformin in WAT and BAT.

Inositol polyphosphate multikinase is a metformin target that regulates cell migration.

Metformin has been shown to alter cell adhesion protein expression, which is thought to play a role in its observed antitumor properties. We found that metformin treatment down-regulated integrin β1 concomitant with the loss of inositol polyphosphate multikinase (IPMK) in murine myocytes, adipocytes, and hepatocytes. To determine if IPMK was upstream of integrin β1 expression, we examined IPMK-/- mouse embryonic fibroblast cells and found that integrins β1 and β3 gene expression was reduced by half, relative to wild-type cells, whereas focal adhesion kinase (FAK) activity and Rho/Rac/Cdc42 protein levels were increased, resulting in migration defects. Using nanonet force microscopy, we determined that cell:extracellular matrix adhesion and cell contractility forces were decreased, confirming the functional relevance of integrin and Rho protein dysregulation. Pharmacological studies showed that inhibition of both FAK1 and proline-rich tyrosine kinase 2 partially restored integrin β1 expression, suggesting negative regulation of integrin β1 by FAK. Together our data indicate that IPMK participates in the regulation of cell migration and provides a potential link between metformin and wound healing impairment.-Tu-Sekine, B., Padhi, A., Jin, S., Kalyan, S., Singh, K., Apperson, M., Kapania, R., Hur, S. C., Nain, A., Kim, S. F. Inositol polyphosphate multikinase is a metformin target that regulates cell migration.