Dissecting the role of AMP-activated protein kinase in human diseases

Astragaloside IV intervenes multi-regulatory cell death forms against doxorubicin-induced cardiotoxicity by regulating AMPKα2 pathway

The clinical use of doxorubicin has been severely limited by doxorubicin-induced cardiotoxicity (DIC). Its mechanism is extremely complex and involves reactive oxygen species overgeneration, DNA damage, and aberrant inflammatory activity, which also involves multi-regulatory cell death mechanisms, including apoptosis, autophagy, and pyroptosis. These mechanisms overlap and crosstalk, resulting in the poor intervention of DIC injury. Astragaloside IV (Ast) has polybioactivity and mitigates DIC damage; however, the underlying mechanisms remain unknown. This study aimed to investigate whether Ast pretreatment (Ast-pre) could protect the myocardium against DIC damage and the underlying mechanisms. In particular, the relationship between Ast-pre, AMPKα2 activity, autophagy, apoptosis, and pyroptosis was explored. Firstly, DIC injury models were established using neonatal rat cardiomyocytes (NRCMs) and mice. And then the effects of adaptive autophagy, anti-pyroptosis and anti-apoptosis of Ast-pre were detected using multi-relevant indexes in NRCMs. Further, how does Ast-pre in AMPKα2 phosphorylation was explored. Finally, these results were validated by DIC injury in mice. Ast-pre, similar to disulfiram (pyroptosis inhibitor), effectively alleviated the inflammatory response, inhibited oxidative and energy stress, prevented mitochondrial dysfunction, and protected the myocardium resisting DIC damage, as demonstrated using multi-indexes. The protection of Ast-pre to DIC damage was almostly canceled by paclitaxel (pyroptosis inducer), 3-methyladenine (autophagy inhibitor), and pAD/AMPKα2-shRNA or compound C (AMPK inhibitor) to varying degrees. In conclusion, Ast-pre could upregulate and activate AMPKα2, enhance adaptive autophagy, and improve energy metabolism and mitochondrial function, thereby alleviate DIC-induced pyroptosis and apoptosis in NRCMs and mice.

2', 3', 5'-tri-O-acetyl-N6-(3-hydroxyphenyl) adenosine alleviates diet-induced hyperlipidemia by modulating intestinal gene expression profiles and metabolic pathway

There is a growing body of evidence suggesting that the composition of intestinal flora plays a significant role in regulating lipid metabolism. 2', 3', 5'-tri-O-acetyl-N6-(3-hydroxyphenyl) adenosine (IMMH007) is a new candidate compound for regulating blood cholesterol and other lipids. In this study, we conducted metagenomic and metabolomic analyses on samples from high-fat diet-fed (HFD) hamsters treated with IMMH007. Our findings revealed that IMM-H007 reversed the imbalance of gut microbiota caused by a high-fat diet. Additionally, it activated adiponectin receptor and pantothenate and CoA biosynthesis pathway-related genes, which are known to regulate lipid and glucose metabolism. Furthermore, IMM-H007 promotes cholesterol metabolism by reducing the abundance of genes and species associated with 7α-dehydroxylation and bile salt hydrolase (BSH). Metabolomics and pharmacological studies have shown that IMM-H007 effectively improved glucose and lipid metabolism disorders caused by HFD, reduced the aggregation of secondary bile acids (SBAs), significantly increased the content of hyodeoxycholic acid (HDCA), and also activated the expression of VDR in the small intestine. As a result, there was a reduction in the leakage of diamine oxidase (DAO) into the bloodstream in hamsters, accompanied by an upregulation of ZO-1 expression in the small intestine. The results suggested that IMM-H007 regulated glucose and lipid metabolism, promoted cholesterol metabolism through activating the expression of VDR, inhibiting inflammatory and improving the permeability of the intestinal barrier. Thus, our study provides new understanding of how IMM-H007 interacts with intestinal function, microbiota, and relevant targets, shedding light on its mechanism of action.

Fine-tuning AMPK in physiology and disease using point-mutant mouse models

AMP-activated protein kinase (AMPK) is an evolutionarily conserved serine/threonine kinase that monitors the cellular energy status to adapt it to the fluctuating nutritional and environmental conditions in an organism. AMPK plays an integral part in a wide array of physiological processes, such as cell growth, autophagy and mitochondrial function, and is implicated in diverse diseases, including cancer, metabolic disorders, cardiovascular diseases and neurodegenerative diseases. AMPK orchestrates many different physiological outcomes by phosphorylating a broad range of downstream substrates. However, the importance of AMPK-mediated regulation of these substrates in vivo remains an ongoing area of investigation to better understand its precise role in cellular and metabolic homeostasis. Here, we provide a comprehensive overview of our understanding of the kinase function of AMPK in vivo, as uncovered from mouse models that harbor phosphorylation mutations in AMPK substrates. We discuss some of the inherent limitations of these mouse models, highlight the broader implications of these studies for understanding human health and disease, and explore the valuable insights gained that could inform future therapeutic strategies for the treatment of metabolic and non-metabolic disorders.

Discovery of Oral AMP-Activated Protein Kinase Activators for Treating Hyperlipidemia

Activation of AMP-activated protein kinase (AMPK) is proposed to alleviate hyperlipidemia. With cordycepin and N6-(2-hydroxyethyl) adenosine (HEA) as lead compounds, a series of adenosine-based derivatives were designed, synthesized, and evaluated on activation of AMPK. Finally, compound V1 was identified as a potent AMPK activator with the lipid-lowering effect. Molecular docking and circular dichroism indicated that V1 exerted its activity by binding to the γ subunit of AMPK. V1 markedly decreased the serum low-density lipoprotein cholesterol levels in C57BL/6 mice, golden hamsters, and rhesus monkeys. V1 was selected as the clinical compound and concluded Phase 1 clinical trials. A single dose of V1 (2000 mg) increased AMPK activation in human erythrocytes after 5 and 12 h of treatment. RNA sequencing data suggested that V1 downregulated expression of genes involved in regulation of apoptotic process, lipid metabolism, endoplasmic reticulum stress, and inflammatory response in liver by activating AMPK.

Preclinical evidence using synthetic compounds and natural products indicates that AMPK represents a potential pharmacological target for the therapy of pulmonary diseases

Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) is a highly conserved eukaryotic enzyme discovered as a key regulator of cellular energy homeostasis, with anti-inflammation, antioxidative stress, anticancer, and antifibrosis beneficial effects. AMPK is dysregulated in human pulmonary diseases such as acute lung injury, nonsmall cell lung cancer, pulmonary fibrosis, chronic obstructive pulmonary disease, and asthma. This review provides an overview of the beneficial role of natural, synthetic, and Chinese traditional medicines AMPK modulators in pulmonary diseases, and highlights the role of the AMPK signaling pathway in the lung, emphasizing the importance of finding lead compounds and drugs that can target and modulate AMPK to treat the lung diseases.

IL-33 Accelerates Chronic Atrophic Gastritis through AMPK-ULK1 Axis Mediated Autolysosomal Degradation of GKN1

Chronic atrophic gastritis (CAG) is a complex disease characterized by atrophy and inflammation in gastric mucosal tissue, especially with high expression of interleukins. However, the interaction and mechanisms between interleukins and gastric mucosal epithelial cells in CAG remain largely elusive. Here, we elucidate that IL-33 stands out as the predominant inflammatory factor in CAG, and its expression is induced by H. pylori and MNNG through the ROS-STAT3 signaling pathway. Furthermore, our findings reveal that the IL-33/ST2 axis is intricately involved in the progression of CAG. Utilizing phosphoproteomics mass spectrometry, we demonstrate that IL-33 enhances autophagy in gastric epithelial cells through the phosphorylation of AMPK-ULK1 axis. Notably, inhibiting autophagy alleviates CAG severity, while augmentation of autophagy exacerbates the disease. Additionally, ROS scavenging emerges as a promising strategy to ameliorate CAG by reducing IL-33 expression and inhibiting autophagy. Intriguingly, IL-33 stimulation promotes GKN1 degradation through the autolysosomal pathway. Clinically, the combined measurement of IL-33 and GKN1 in serum shows potential as diagnostic markers. Our findings unveil an IL-33-AMPK-ULK1 regulatory mechanism governing GKN1 protein stability in CAG, presenting potential therapeutic targets for its treatment.

Energy metabolism and redox balance: How phytochemicals influence heart failure treatment

Heart Failure (HF) epitomizes a formidable global health quandary characterized by marked morbidity and mortality. It has been established that severe derangements in energy metabolism are central to the pathogenesis of HF, culminating in an inadequate cardiac energy milieu, which, in turn, precipitates cardiac pump dysfunction and systemic energy metabolic failure, thereby steering the trajectory and potential recuperation of HF. The conventional therapeutic paradigms for HF predominantly target amelioration of heart rate, and cardiac preload and afterload, proffering symptomatic palliation or decelerating the disease progression. However, the realm of therapeutics targeting the cardiac energy metabolism remains largely uncharted. This review delineates the quintessential characteristics of cardiac energy metabolism in healthy hearts, and the metabolic aberrations observed during HF, alongside the associated metabolic pathways and targets. Furthermore, we delve into the potential of phytochemicals in rectifying the redox disequilibrium and the perturbations in energy metabolism observed in HF. Through an exhaustive analysis of recent advancements, we underscore the promise of phytochemicals in modulating these pathways, thereby unfurling a novel vista on HF therapeutics. Given their potential in orchestrating cardiac energy metabolism, phytochemicals are emerging as a burgeoning frontier for HF treatment. The review accentuates the imperative for deeper exploration into how these phytochemicals specifically intervene in cardiac energy metabolism, and the subsequent translation of these findings into clinical applications, thereby broadening the horizon for HF treatment modalities.

The mechanism and targeted intervention of the HIF-1 pathway in improving atherosclerotic heart's sensitivity to ischemic postconditioning

BACKGROUND

IPoC possesses a preventive effect against IR injury in healthy myocardium, but IPoC's protective effect on atherosclerotic myocardium is controversial. The current investigation aims to determine whether IPoC remains protective in atherosclerotic myocardium subjected to ischemia-reperfusion (IR) injury; to explore the specific mechanisms by which IPoC exerts cardioprotection; to explore whether HIF-1 upregulation combined with IPoC could further the provide cardioprotection; and to gaze at the specific mechanism whereby combined treatment expert the cardioprotection.

METHODS

ApoE-/- mice fed with a high-fat diet (HFD) were used to develop a model of atherosclerosis. The myocardial IR model was induced by occlusion of the left anterior descending (LAD) artery for 45 min, followed by reperfusion for 120 min. The protection of IPoC in both healthy and atherosclerotic myocardium was evaluated by measuring oxidative stress, apoptosis, infarct size, pathology, mitochondrial dysfunction and morphology of myocardium. The specific mechanism by which IPoC exerts cardioprotection in healthy and atherosclerotic myocardium was observed by measuring the expression of proteins involved in HIF-1, APMK and RISK pathways. The effect of HIF-1α overexpression on the cardioprotection by IPoC was observed by intravenous AAV9 -HIF-1α injection.

RESULTS

In healthy ischemic myocardium, IPoC exerted myocardial protective effects (antioxidant, anti-apoptosis, and improved mitochondrial function) through the activation of HIF-1, AMPK and RISK pathways. In atherosclerotic ischemic myocardium, IPoC exerted cardioprotection only through the activation of HIF-1 pathway; however, HIF-1 overexpression combined IPoC restored the activation of AMPK and RISK pathways, thereby further alleviating the myocardial IR injury.

CONCLUSIONS

In the atherosclerotic state, the HIF-1 pathway is the intrinsic mechanism by which IPoC exerts cardioprotective effects. The combination of HIF-1 upregulation and IPoC has a significant effect in reducing myocardial injury, which is worth being promoted and advocated. In addition, HIF-1-AMPK and HIF-1-RISK may be two endogenous cardioprotective signalling pathways with great value, which deserve to be thoroughly investigated in the future.

Human immunodeficiency virus and antiretroviral therapy-mediated immune cell metabolic dysregulation in children born to HIV-infected women: potential clinical implications

Commencing lifelong antiretroviral therapy (ART) immediately following HIV diagnosis (Option B+) has dramatically improved the health of HIV-infected women and their children, with the majority being of HIV-exposed children born uninfected (HEU). This success has led to an increasing population of HIV-infected women receiving ART during pregnancy and children exposed to ART in utero. Nonetheless, a small proportion of children are still infected with HIV (HEI) each year. HEI children suffer from reduced immunocompetence and host-defence, due to CD4+ T lymphocyte depletion, but also dysregulation of other immune cells including CD8+ T lymphocytes, natural killer (NK) cells, macrophages including B lymphocytes. Furthermore, although HEU children are uninfected, altered immune responses are observed and associated with increased vulnerability to infections. The mechanisms underlying immune dysregulation in HEU children remain poorly described. Building on early studies, emerging data suggests that HIV/ART exposure early in life affects cell metabolic function of HEU children. Prenatal HIV/ART exposure has been associated with dysregulation of mitochondria, including impaired DNA polymerase activity. Furthermore, dysregulation of oxidative phosphorylation (OXPHOS) causes a decreased generation of adenosine triphosphate (ATP) and increased production of reactive oxygen species (ROS), resulting in oxidative stress. These altered metabolic processes can affect immune cell viability and immune responses. Recent studies have indicated that immune-metabolic dysregulation may contribute to HIV-associated pathogenesis and clinical observations associated with HIV and ART exposure in HEU/HEI children. Given the critical role metabolic processes in immune cell functioning, immune-metabolic dysregulation in HEU and HEI children may have implications in effective host-defence responses against pathogens, as well as efficacy of standard ART regimens and future novel HIV cure approaches in HEI children. At the same time, targeting metabolic pathways of immune cells may provide safer and novel approaches for HIV cure strategies. Here, we review the current literature investigating immune-metabolic dysregulation in paediatric HIV pathogenesis.

Ephedra Herb extract ameliorates adriamycin-induced nephrotic syndrome in rats via the CAMKK2/AMPK/mTOR signaling pathway

This study aimed to investigate the effect and mechanisms of Ephedra Herb (EH) extract on adriamycin-induced nephrotic syndrome (NS), providing an experimental basis for the clinical treatment of NS. Hematoxylin and eosin staining, creatinine, urea nitrogen, and kidn injury molecule-1 were used to evaluate the activities of EH extract on renal function. The levels of inflammatory factors and oxidative stress were detected by kits. The levels of reactive oxygen species, immune cells, and apoptosis were measured by flow cytometry. A network pharmacological approach was used to predict the potential targets and mechanisms of EH extract in the treatment of NS. The protein levels of apoptosis-related proteins and CAMKK2, p-CAMKK2, AMPK, p-AMPK, mTOR and p-mTOR in the kidneys were detected by Western blot. The effective material basis of EH extract was screened by MTT assay. The AMPK pathway inhibitor (compound C, CC) was added to investigate the effect of the potent material basis on adriamycin-induced cell injury. EH extract significantly improved renal injury and relieve inflammation, oxidative stress, and apoptosis in rats. Network pharmacology and Western blot results showed that the effect of EH extract on NS may be associated with the CAMKK2/AMPK/mTOR signaling pathway. Moreover, methylephedrine significantly ameliorated adriamycin-induced NRK-52e cell injury. Methylephedrine also significantly improved the phosphorylation of AMPK and mTOR, which were blocked by CC. In sum, EH extract may ameliorate renal injury via the CAMKK2/AMPK/mTOR signaling pathway. Moreover, methylephedrine may be one of the material bases of EH extract.

Amniotic fluid stem cell attenuated necrotizing enterocolitis progression by promoting Rspo3/AMPKα axis

R-spondin 3 (Rspo3) is involved in various cellular processes. The alteration of Rspo3 participates in the differentiation of intestinal epithelial cells which are the crucial effector cells during necrotizing enterocolitis (NEC) development. Amniotic fluid stem cells (AFSCs) were recently indicated as a potential approach for NEC therapy. This study aimed to illustrate the regulatory role and mechanism of Rspo3 in the pathogenesis of NEC and whether AFSCs therapy would impact NEC by mediating Rspo3. First, the alteration of Rspo3 was investigated in the serum and tissues of NEC patients, and an in vitro cell model induced by LPS. A gain-of-function assay was conducted to explore the function of Rspo3 in NEC. Through the analysis of adenosine 5'-monophosphate-activated protein kinase α (AMPKα) activation, the mechanism of Rspo3-mediated NEC progression was demonstrated. Finally, AFSCs were used to coculture human intestinal epithelial cells (HIECs) and the impacts on NEC development were also explored. The results found that Rspo3 was dramatically depressed during NEC progression and reversing Rspo3 expression ameliorated LPS-induced injury, inflammation, oxidative stress and tight junction dysregulation in HIECs. Besides, Rspo3 overexpression reversed AMPKα inactivation induced by NEC and an AMPKα inhibitor, Compound C, blocked the effect of Rspo3 overexpression on NEC. AFSCs treatment was beneficial for NEC therapy by restoring Rspo3 expression which was counteracted by exosome inhibitor. Generally, AFSCs attenuated NEC progression by promoting the Rspo3/AMPKα axis which might exert via the secretion of exosomes. Our conclusions might be valuable for NEC diagnosis and therapy.

The Core-Targeted RRM2 Gene of Berberine Hydrochloride Promotes Breast Cancer Cell Migration and Invasion via the Epithelial-Mesenchymal Transition

Berberine hydrochloride (BBR) could inhibit the proliferation, migration, and invasion of various cancer cells. As the only enzyme for the de novo synthesis of ribonucleotides, RRM2 is closely related to the development of tumorigenesis. However, not much is currently known about the functional roles of RRM2 in breast cancer (BRCA), and whether BBR regulates the migration and invasion of BRCA cells by regulating the expression of RRM2 remains to be determined. We study the effects of BBR on BRCA cell proliferation in vitro and tumorigenesis in vivo by using colony formation assays, EdU assays, and xenograft models. Transcriptome sequencing, the random forest algorithm, and KEGG analysis were utilized to explore the therapeutic target genes and relative pathways. The expression of RRM2 in BRCA patients was analyzed with The Cancer Genome Atlas (TCGA) dataset, the GEPIA website tool, the Gene Expression Omnibus (GEO) database, and the UALCAN database. The survival probability of BRCA patients could be predicted by survival curve and nomogram analysis. Molecular docking was used to explore the affinity between BBR and potential targets. Gain- and loss-of-function methods were employed to explore the biological process in RRM2 participants. We comprehensively investigated the pharmacological characteristics of BBR on BRCA cell lines and discovered that BBR could inhibit the proliferation of BRCA cells in vitro and in vivo. Combining transcriptome sequencing and KEGG analysis, we found that BBR mainly affected the biological behavior of BRCA cells via HIF-1α and AMPK signal pathways. Additionally, by using bioinformatics and molecular docking, we demonstrated that RRM2 plays an oncogenic role in BRCA samples and that it acts as the hub gene of BBR on BRCA cells. Knockdown and overexpression studies indicated that RRM2 promoted BRCA cell migration as well as invasion in vitro by affecting the epithelial-to-mesenchymal transition (EMT). Our study demonstrated the significance of BBR regulating HIF-1α and AMPK signaling pathways in BRCA cells. Moreover, we revealed the carcinogenic role and potential mechanism of RRM2 as a core regulatory factor of BBR in BRCA in controlling BRCA invasion, migration, and EMT, suggesting that RRM2 may be a therapeutic target and prognostic biomarker for BRCA therapy.

Britanin relieves ferroptosis-mediated myocardial ischaemia/reperfusion damage by upregulating GPX4 through activation of AMPK/GSK3β/Nrf2 signalling

CONTEXT

Ferroptosis was described as an important contributor to the myocardial ischaemia/reperfusion (MIR) injury, and britanin (Bri) was reported to exert antitumor and anti-inflammatory activities.

OBJECTIVE

Our study explores the effect and mechanism of Bri on MIR damage.

MATERIALS AND METHODS

The rat model of MIR was established by ligation of the left anterior descending coronary artery. Male Sprague-Dawley (SD) rats were divided into three groups: sham group (n = 6), MIR group (n = 6) and MIR + Bri group (n = 6; 50 mg/kg). Rats were intragastrically pre-treated with Bri or normal saline once daily for 3 days. To further verify the role and mechanism of Bri, H9C2 cells were subjected to hypoxia plus reoxygenation (H/R) to induce the in vitro model of MIR.

RESULTS

Compared with MIR rats, Bri significantly decreased infarct area (22.50% vs. 38.67%), myocardial apoptosis (23.00% vs. 41.5%), creatine phosphokinase (0.57 U/mL vs. 0.76 U/mL), and lactate dehydrogenase levels (3.18 U/mL vs. 5.17 U/mL), concomitant with alleviation of ferroptosis. Mechanistically, Bri treatment induced the activation of the adenosine monophosphate activated protein kinase (AMPK)/glycogen synthase kinase 3β (GSK3β)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in vivo. In addition, the AMPK/GSK3β/Nrf2 pathway participated in the regulation of glutathione peroxidase 4 (GPX4) expression, and silencing of Nrf2 attenuated the effect of Bri on H/R-induced cell injury.

DISCUSSION AND CONCLUSIONS

Bri protected against ferroptosis-mediated MIR damage by upregulating GPX4 through activation of the AMPK/GSK3β/Nrf2 signalling, suggesting that Bri might become a novel therapeutic agent for MIR.

Shear Stress and Metabolic Disorders-Two Sides of the Same Plaque

Significance: Shear stress and metabolic disorder are the two sides of the same atherosclerotic coin. Atherosclerotic lesions are prone to develop at branches and curvatures of arteries, which are exposed to oscillatory and low shear stress exerted by blood flow. Meanwhile, metabolic disorders are pivotal contributors to the formation and advancement of atherosclerotic plaques. Recent Advances: Accumulated evidence has provided insight into the impact and mechanisms of biomechanical forces and metabolic disorder on atherogenesis, in association with mechanotransduction, epigenetic regulation, and so on. Moreover, recent studies have shed light on the cross talk between the two drivers of atherosclerosis. Critical Issues: There are extensive cross talk and interactions between shear stress and metabolic disorder during the pathogenesis of atherosclerosis. The communications may amplify the proatherogenic effects through increasing oxidative stress and inflammation. Nonetheless, the precise mechanisms underlying such interactions remain to be fully elucidated as the cross talk network is considerably complex. Future Directions: A better understanding of the cross talk network may confer benefits for a more comprehensive clinical management of atherosclerosis. Critical mediators of the cross talk may serve as promising therapeutic targets for atherosclerotic vascular diseases, as they can inhibit effects from both sides of the plaque. Hence, further in-depth investigations with advanced omics approaches are required to develop novel and effective therapeutic strategies against atherosclerosis. Antioxid. Redox Signal. 37, 820-841.

Rutin promotes white adipose tissue "browning" and brown adipose tissue activation partially through the calmodulin-dependent protein kinase kinase β/AMP-activated protein kinase pathway

Promoting white adipose tissue (WAT) "browning" and brown adipose tissue (BAT) activation could contribute to increasing energy expenditure. We explored the mechanisms by which the natural compound rutin induced adipose tissue differentiation and ameliorated obesity in vivo and in vitro. 3T3-L1 preadipocytes were cultured in adipogenic differentiation media with/out rutin. Male C57BL/6 mice (n = 6) were fed a high-fat diet (HFD) for 12 weeks with/out rutin. In HFD-fed mice, rutin treatment significantly inhibited weight gain, improved the metabolic profile of plasma samples, decreased the weights of epididymal WAT (eWAT), inguina WAT (iWAT), and liver, and adipocyte size. Furthermore, rutin also increased the expression of uncoupling protein 1 (Ucp-1) and other thermogenic markers in the WAT and BAT. In 3T3-L1 cells, rutin effectively reduced the formation of lipid droplets, stimulated the expression of thermogenic markers, and reduced the expression of adipogenic genes. Additionally, rutin markedly upregulated the AMP-activated protein kinase (AMPK) pathway, and these effects were diminished by treatment with the AMPK inhibitor compound C (CC). Pretreatment with the calmodulin-dependent protein kinase kinase β (CaMKKβ) inhibitor STO-609 blocked the induction of thermogenic markers in 3T3-L1 cells by rutin. Our results indicated that rutin increased energy consumption, induced WAT "browning" and BAT activation, and thus was a promising target for the development of new therapeutic approaches to improve adipose tissue energy metabolism.

Targeting PFKL with penfluridol inhibits glycolysis and suppresses esophageal cancer tumorigenesis in an AMPK/FOXO3a/BIM-dependent manner

As one of the hallmarks of cancer, metabolic reprogramming leads to cancer progression, and targeting glycolytic enzymes could be useful strategies for cancer therapy. By screening a small molecule library consisting of 1320 FDA-approved drugs, we found that penfluridol, an antipsychotic drug used to treat schizophrenia, could inhibit glycolysis and induce apoptosis in esophageal squamous cell carcinoma (ESCC). Gene profiling and Ingenuity Pathway Analysis suggested the important role of AMPK in action mechanism of penfluridol. By using drug affinity responsive target stability (DARTS) technology and proteomics, we identified phosphofructokinase, liver type (PFKL), a key enzyme in glycolysis, as a direct target of penfluridol. Penfluridol could not exhibit its anticancer property in PFKL-deficient cancer cells, illustrating that PFKL is essential for the bioactivity of penfluridol. High PFKL expression is correlated with advanced stages and poor survival of ESCC patients, and silencing of PFKL significantly suppressed tumor growth. Mechanistically, direct binding of penfluridol and PFKL inhibits glucose consumption, lactate and ATP production, leads to nuclear translocation of FOXO3a and subsequent transcriptional activation of BIM in an AMPK-dependent manner. Taken together, PFKL is a potential prognostic biomarker and therapeutic target in ESCC, and penfluridol may be a new therapeutic option for management of this lethal disease.

In Vivo Hypoglycemic Effects, Potential Mechanisms and LC-MS/MS Analysis of Dendropanax Trifidus Sap Extract

Extracts of medicinal plants have been widely used to benefit human health. Dendropanax morbiferus (DM) has been well-studied for its anti-inflammatory and anti-oxidative effects, while Dendropanax trifidus (DT) is a lesser-known ecotype phylogenetically similar to DM, which has received significantly less attention. Studies thus far have primarily focused on leaf and bark extracts of DM, and not much is yet known about the properties of either DM or DT sap. Therefore, here we performed in vivo toxicity and efficacy studies, in order to assess the biological effects of DT sap. To establish a safe dosage range, single dose or two-week daily administrations of various concentrations were performed for ICR mice. Measurements of survival ratio, body/organ weight, blood chemistry, histochemistry and Western blots were performed. A concentration of ≤0.5 mg/g DT sap was found to be safe for long-term administration. Interestingly, DT sap significantly reduced blood glucose in female mice. In addition, increasing concentrations of DT sap decreased phosphorylated (p) insulin receptor substrate (IRS)-1(ser1101)/IRS-1 in liver tissues, while increasing pAMP-activated protein kinase (AMPK)/AMPK in both the liver and spleen. To analyze its components, liquid chromatography-tandem mass spectrometry of DT sap was performed in comparison with Acer saccharum (AS) sap. Components such as estradiol, trenbolone, farnesol, dienogest, 2-hydroxyestradiol and linoleic acid were found to be highly enriched in DT sap compared to AS sap. Our results indicate DT sap exhibits hypoglycemic effects, which may be due to the abundance of the bioactive components.

Knockdown of LKB1 Sensitizes Endometrial Cancer Cells via AMPK Activation

Metformin is an anti-diabetic drug and has anticancer effects on various cancers. Several studies have suggested that metformin reduces cell proliferation and stimulates cell-cycle arrest and apoptosis. However, the definitive molecular mechanism of metformin in the pathophysiological signaling in endometrial tumorigenesis and metastasis is not clearly understood. In this study, we examined the effects of metformin on the cell viability and apoptosis of human cervical HeLa and endometrial HEC-1-A and KLE cancer cells. Metformin suppressed cell growth in a dose-dependent manner and dramatically evoked apoptosis in HeLa cervical cancer cells, while apoptotic cell death and growth inhibition were not observed in endometrial (HEC-1-A, KLE) cell lines. Accordingly, the p27 and p21 promoter activities were enhanced while Bcl-2 and IL-6 activities were significantly reduced by metformin treatment. Metformin diminished the phosphorylation of mTOR, p70S6K and 4E-BP1 by accelerating adenosine monophosphateactivated kinase (AMPK) in HeLa cancer cells, but it did not affect other cell lines. To determine why the anti-proliferative effects are observed only in HeLa cells, we examined the expression level of liver kinase B1 (LKB1) since metformin and LKB1 share the same signalling system, and we found that the LKB1 gene is not expressed only in HeLa cancer cells. Consistently, the overexpression of LKB1 in HeLa cancer cells prevented metformin-triggered apoptosis while LKB1 knockdown significantly increased apoptosis in HEC-1-A and KLE cancer cells. Taken together, these findings indicate an underlying biological/physiological molecular function specifically for metformin-triggered apoptosis dependent on the presence of the LKB1 gene in tumorigenesis.

Metformin attenuates silica-induced pulmonary fibrosis via AMPK signaling

Background

Silicosis is one of the most common occupational pulmonary fibrosis caused by respirable silica-based particle exposure, with no ideal drugs at present. Metformin, a commonly used biguanide antidiabetic agent, could activate AMP-activated protein kinase (AMPK) to exert its pharmacological action. Therefore, we sought to investigate the role of metformin in silica-induced lung fibrosis.

Methods

The anti-fibrotic role of metformin was assessed in 50 mg/kg silica-induced lung fibrosis model. Silicon dioxide (SiO₂)-stimulated lung epithelial cells/macrophages and transforming growth factor-beta 1 (TGF-β1)-induced differentiated lung fibroblasts were used for in vitro models.

Results

At the concentration of 300 mg/kg in the mouse model, metformin significantly reduced lung inflammation and fibrosis in SiO₂-instilled mice at the early and late fibrotic stages. Besides, metformin (range 2–10 mM) reversed SiO₂-induced cell toxicity, oxidative stress, and epithelial-mesenchymal transition process in epithelial cells (A549 and HBE), inhibited inflammation response in macrophages (THP-1), and alleviated TGF-β1-stimulated fibroblast activation in lung fibroblasts (MRC-5) via an AMPK-dependent pathway.

Conclusions

In this study, we identified that metformin might be a potential drug for silicosis treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03036-5.

Metabolic impacts of cordycepin on hepatic proteomic expression in streptozotocin-induced type 1 diabetic mice

Type 1 Diabetes mellitus (T1DM) is associated with abnormal liver function, but the exact mechanism is unclear. Cordycepin improves hepatic metabolic pathways leading to recovery from liver damage. We investigated the effects of cordycepin in streptozotocin-induced T1DM mice via the expression of liver proteins. Twenty-four mice were divided into four equal groups: normal (N), normal mice treated with cordycepin (N+COR), diabetic mice (DM), and diabetic mice treated with cordycepin (DM+COR). Mice in each treatment group were intraperitoneally injection of cordycepin at dose 24 mg/kg for 14 consecutive days. Body weight, blood glucose, and the tricarboxylic acid cycle intermediates were measured. Liver tissue protein profiling was performed using shotgun proteomics, while protein function and protein-protein interaction were predicted using PANTHER and STITCH v.5.0 software, respectively. No significant difference was observed in fasting blood glucose levels between DM and DM+COR for all time intervals. However, a significant decrease in final body weight, food intake, and water intake in DM+COR was found. Hepatic oxaloacetate and citrate levels were significantly increased in DM+COR compared to DM. Furthermore, 11 and 36 proteins were only expressed by the N+COR and DM+COR groups, respectively. Three unique proteins in DM+COR, namely, Nfat3, Flcn, and Psma3 were correlated with the production of ATP, AMPK signaling pathway, and ubiquitin proteasome system (UPS), respectively. Interestingly, a protein detected in N+COR and DM+COR (Gli3) was linked with the insulin signaling pathway. In conclusion, cordycepin might help in preventing hepatic metabolism by regulating the expression of energy-related protein and UPS to maintain cell survival. Further work on predicting the performance of metabolic mechanisms regarding the therapeutic applications of cordycepin will be performed in future.

Interferon Regulatory Factor-2 Binding Protein 2 Ameliorates Sepsis-Induced Cardiomyopathy via AMPK-Mediated Anti-Inflammation and Anti-Apoptosis

Cardiomyopathy commonly occurs after sepsis and is closely associated with high mortality in clinic. Interferon regulatory factor-2 binding protein 2 (IRF2BP2) has been identified as a negative regulator of inflammation, but its role in septic cardiomyopathy is unknown. The current study aims to illuminate the regulatory function of IRF2BP2 on sepsis-induced cardiomyopathy and to explore the underlying mechanisms. Protein expression of IRF2BP2 in response to sepsis-induced cardiomyopathy was examined in the heart of mice challenged by LPS intraperitoneal injection. AAV9-delivered IRF2BP2 overexpression in the heart was applied to evaluate the regulatory role of IRF2BP2 in sepsis-induced myocardial depression, inflammatory response, and cell death. The molecular mechanisms underlying IRF2BP2-regulated cardiomyopathy were explored using western blot screening assay. Primary cardiomyocytes have been isolated to further confirm the role and mechanism of IRF2BP2 during septic cardiomyopathy. IRF2BP2 expression was dramatically increased in the heart of mice after LPS administration. AAV9-mediated IRF2BP2 overexpression significantly improved sepsis-induced cardiac dysfunction, inhibited inflammatory cell infiltration and cytokine production, and blocked cell death after LPS treatment. Mechanistically, IRF2BP2 activated AMPK signaling in cardiomyocytes, while inhibiting AMPK activation largely reversed IRF2BP2-benefited inflammatory suppression and cell survival. These findings clearly demonstrated that IRF2BP2 is a potent suppressor of sepsis-induced myocardial depression and related heart impairment. Targeting IRF2BP2 represents a promising therapeutic strategy for septic cardiomyopathy.

Rationale for the use of metformin and exercise to counteract statin-associated side effects

INTRODUCTION

Statins are the most widely prescribed drugs for lowering low-density lipoprotein cholesterol (LDL-C) and reducing cardiovascular morbidity and mortality. They are usually well-tolerated, but have two main safety concerns: statin-associated muscle symptoms (SAMS) and new-onset type 2 diabetes (NOD).

METHODS

A PubMed search was carried out using the following key words were used: statins, statin-associated muscle symptoms, statin myalgia, statin-associated diabetes, metformin and statins, exercise and statins.

RESULTS

Mitochondrial damage and muscle atrophy are likely the central mechanisms producing SAMS, whereas decreased glucose transport, fatty acid oxidation and insulin secretion are likely involved in the development of NOD. Metformin and exercise training share many pathways that could potentially contrast SAMS and NOD. Clinical evidence also supports the combination of statins with metformin and exercise.

CONCLUSION

This combination appears attractive both from a clinical and an economical viewpoint, since all three therapies are highly cost-effective and their combination could result in diabetes and cardiovascular disease prevention.

Energy metabolism disorders and potential therapeutic drugs in heart failure

Heart failure (HF) is a global public health problem with high morbidity and mortality. A large number of studies have shown that HF is caused by severe energy metabolism disorders, which result in an insufficient heart energy supply. This deficiency causes cardiac pump dysfunction and systemic energy metabolism failure, which determine the development of HF and recovery of heart. Current HF therapy acts by reducing heart rate and cardiac preload and afterload, treating the HF symptomatically or delaying development of the disease. Drugs aimed at cardiac energy metabolism have not yet been developed. In this review, we outline the main characteristics of cardiac energy metabolism in healthy hearts, changes in metabolism during HF, and related pathways and targets of energy metabolism. Finally, we discuss drugs that improve cardiac function via energy metabolism to provide new research ideas for the development and application of drugs for treating HF.

AMPK and its Activator Berberine in the Treatment of Neurodegenerative Diseases

Neurodegenerative disorders are heterogeneous diseases associated with either acute or progressive neurodegeneration, causing the loss of neurons and axons in the central nervous system (CNS), showing high morbidity and mortality, and there are only a few effective therapies. Here, we summarized that the energy sensor adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), and its agonist berberine can combat the common underlying pathological events of neurodegeneration, including oxidative stress, neuroinflammation, mitochondrial disorder, glutamate excitotoxicity, apoptosis, autophagy disorder, and disruption of neurovascular units. The abovementioned effects of berberine may primarily depend on activating AMPK and its downstream targets, such as the mammalian target of rapamycin (mTOR), sirtuin1 (SIRT1), nuclear factor erythroid-2 related factor-2 (Nrf2), nuclear factor-κB (NF-κB), phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), nicotinamide adenine dinucleotide (NAD+), and p38 mitogen-activated protein kinase (p38 MAPK). It is hoped that this review will provide a strong basis for further scientific exploration and development of berberine's therapeutic potential against neurodegeneration.

AMPK activator C24 inhibits hepatic lipogenesis and ameliorates dyslipidemia in HFHC diet-induced animal models

Dyslipidemia is a chronic metabolic disease characterized by elevated levels of lipids in plasma. Recently, various studies demonstrate that the increased activity of adenosine 5'-monophosphate-activated protein kinase (AMPK) causes health benefits in energy regulation. Thus, great efforts have been made to develop AMPK activators as a metabolic syndrome treatment. In the present study, we investigated the effects of the AMPK activator C24 on dyslipidemia and the potential mechanisms. We showed that C24 (5-40 μM) dose-dependently increased the phosphorylation of AMPKα and acetyl-CoA carboxylase (ACC), and inhibited lipogenesis in HepG2 cells. Using compound C, an AMPK inhibitor, or hepatocytes isolated from liver tissue-specific AMPK knockout AMPKα1α2fl/fl;Alb-cre mice (AMPK LKO), we demonstrated that the lipogenesis inhibition of C24 was dependent on hepatic AMPK activation. In rabbits with high-fat and high-cholesterol diet-induced dyslipidemia, administration of C24 (20, 40, and 60 mg · kg-1· d-1, ig, for 4 weeks) dose-dependently decreased the content of TG, total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) in plasma and played a role in protecting against hepatic dysfunction by decreasing lipid accumulation. A lipid-lowering effect was also observed in high-fat and high-cholesterol diet-fed hamsters. In conclusion, our results demonstrate that the small molecular AMPK activator C24 alleviates hyperlipidemia and represents a promising compound for the development of a lipid-lowering drug.

Glucocorticoid receptor-targeted liposomal delivery system for delivering small molecule ESC8 and anti-miR-Hsp90 gene construct to combat colon cancer

High mortality rate in colon cancer patients is often attributed to late diagnosis. To overcome the conventional chemotherapy associated challenges, chemotherapeutic drugs (single or combination) or genetic drugs are often delivered using ligand-modified delivery systems that selectively target over expressed receptors or particular receptors that act abnormally in cancer cells. In the current investigation, first we assessed anti-colon cancer effect of a cationic estrogenic molecule, ESC8 which was earlier shown to act against estrogen receptor (ER) ± breast cancer cells. We found that against both colon and breast cancer cells the anticancer activity is intervened by AMPK-mTOR pathway and at the same time it acts as anti-angiogenic agent. It also showed enhancement of mesenchymal-to-epithelial (MET) transition as well as reduction of cyclin D in both cells. Earlier we demonstrated the use of glucocorticoid receptor (GR) targeted cationic liposomal delivery system carrying anti-Hsp90 plasmid and ESC8 to act as potent anti-skin cancer therapeutics. As ESC8 demonstrated anti-colon cancer effect in vitro, in here, we used the same GR-targeted liposomal formulation but carrying a more fusogenic cationic lipid D1 and used against colon tumor orthotopic model in mice. We show that GR targeted formulation (D1XE-Hsp90) exhibited efficient cellular uptake, transfection and selective cytotoxicity in colon cancer cells, tumor-targeted bio-distribution and enhanced survivability, reduced tumor size in orthotopic colon tumor-bearing mice. The tumor sections exhibited reduced tumor proliferation as well as neo-vascularization, thus supporting the holistic antitumor effect of the D1XE-Hsp90 formulation. Over all our results establish the GR-targeted D1XE-Hsp90 formulation as potent anti-colon cancer therapeutics.

Rosmarinic Acid Protects Mice from Concanavalin A-Induced Hepatic Injury through AMPK Signaling

Rosmarinic acid (RA) is extensively utilized in herbal medicine in China. The AMP-activated protein kinase (AMPK) signaling can be activated by RA and inhibited by the synthetic, reversible AMP-competitive inhibitor, Compound C (CC). The objective of this study was to investigate the role of AMPK signaling involving the protective effects of RA on concanavalin A (Con A)-induced autoimmune hepatitis (AIH) in mice. BALB/c mice were treated with RA, with or without CC, followed by the pretreatment with Con A. Analysis of serum aminotransferases and cytokines were conducted and liver tissue histology was performed to evaluate hepatic injury. Cytokine levels in serum and hepatic tissue were respectively measured by enzyme-linked immunoassay (ELISA) and used quantitative (q)PCR. Levels of phosphorylated acetyl CoA carboxylase in the liver, representing AMPK activation, were detected by Western blotting. Compared with the Con A group, serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in RA group (100 and 150 mg/kg/d) were significantly reduced. RA also reduced hepatocyte swelling, cell death, and infiltration of leukocytes in the liver of Con A-treated mice. Serum levels of cytokines, such as interferon-γ (IFN-γ), interleukin-2 (IL-2) and interleukin-1β (IL-1β), were reduced by RA pretreatment, while the levels of serum interleukin-10 (IL-10), an anti-inflammatory cytokine, was elevated. These protective effects were reversed by treatment with CC. RA treatment reduced the hepatic damage via the activation of AMPK in the mice of Con A-induced. So RA acts as a potential part in the therapy of autoimmune hepatitis.

GPA peptide inhibits NLRP3 inflammasome activation to ameliorate colitis through AMPK pathway

Ulcerative colitis (UC) is a chronic and idiopathic inflammatory disease that affects the colon, resulting in immune dysregulation and the production of large amounts of pro-inflammatory cytokines. Pyroptosis and NLRP3 inflammasome are associated with various kinds of inflammatory diseases including colitis. The purpose of this study is to investigate the protective effects and regulatory mechanism of Gly-Pro-Ala (GPA) peptide on DSS-induced colitis. In vivo, we find GPA peptide could exert anti-inflammatory effects on DSS-induced mice colitis, and its anti-inflammatory effects are abolished in NLRP3^-/- mice. In macrophage, GPA suppresses the assembly of NLRP3 inflammasome and GSDMD cleavage. Furthermore, GPA maintains mitochondrial homeostasis through inhibiting ROS, mtDNA and NLRP3 mitochondrial localization, with other signals related to NLRP3 inflammasome unaffected. Furthermore, the inhibitory effects of GPA on reactive oxygen species (ROS) are found to be achieved by increasing AMPK phosphorylation. Our results suggest that GPA inhibits NLRP3 inflammasome activation through increasing AMPK phosphorylation to suppress ROS, and can be applied in the prevention of colitis through targeting NLRP3.

Functional nano-vector boost anti-atherosclerosis efficacy of berberine in Apoe (-/-) mice

Atherosclerosis (AS) is the leading cause of heart attacks, stroke, and peripheral vascular disease. Berberine (BBR), a botanical medicine, has diversified anti-atherosclerotic effects but with poor absorption. The aim of this study was to develop an effective BBR-entrapped nano-system for treating AS in high-fat diet (HFD)-fed Apoe ^(-/-) mice, and also explore the possible underlying mechanisms involved. Three d-α-tocopherol polyethylene glycol (PEG) succinate (TPGS) analogues with different PEG chain lengths were synthesized to formulate BBR-entrapped micelles. HFD-fed Apoe ^(-/-) mice were administered with optimized formula (BBR, 100 mg/kg/day) orally for 5 months. The artery plaque onset and related metabolic disorders were evaluated, and the underlying mechanisms were studied. Our data showed that, BT₁₅₀₀M increased BBR deposition in liver and adipose by 107.6% and 172.3%, respectively. In the Apoe ^(-/-) mice, BT₁₅₀₀M ameliorated HFD-induced hyperlipidemia and lipid accumulation in liver and adipose. BT₁₅₀₀M also suppressed HFD-induced chronic inflammation as evidenced by the reduced liver and adipose levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β); and decreased plasma level of TNF-α, IL-6, IL-1β, interferon-γ (IFN-γ), monocyte chemotactic protein (MCP), and macrophage inflammatory factor (MIP). The mechanism study showed that BT₁₅₀₀M changed Ampk and Nf-κb gene expression, and interrupted a crosstalk process between adipocytes and macrophages. Further investigation proved that BT₁₅₀₀M decreased endothelial lesion and subsequent macrophage activation, cytokines release, as well as cholesteryl ester gathering in the aortic arch, resulting in ameliorated artery plaque build-up. Our results provide a practical strategy for treating AS using a BBR-entrapped nano-system.

The autophagy-activating kinase ULK1 mediates clearance of free α-globin in β-thalassemia

In β-thalassemia, accumulated free α-globin forms intracellular precipitates that impair erythroid cell maturation and viability. Protein quality control systems mitigate β-thalassemia pathophysiology by degrading toxic free α-globin, although the associated mechanisms are poorly understood. We show that loss of the autophagy-activating Unc-51-like kinase 1 (Ulk1) gene in β-thalassemic mice reduces autophagic clearance of α-globin in red blood cell precursors and exacerbates disease phenotypes, whereas inactivation of the canonical autophagy-related 5 (Atg5) gene has relatively minor effects. Systemic treatment with the mTORC1 inhibitor rapamycin reduces α-globin precipitates and lessens pathologies in β-thalassemic mice via an ULK1-dependent pathway. Similarly, rapamycin reduces free α-globin accumulation in erythroblasts derived from CD34⁺ cells of β-thalassemic individuals. Our findings define a drug-regulatable pathway for ameliorating β-thalassemia.

Anti-arthritis effect of berberine associated with regulating energy metabolism of macrophages through AMPK/ HIF-1α pathway

Berberine (BBR) is the effective constituent of Cortex phellodendri and was characterized as an excellent anti-microbial agent with significant anti-inflammatory effects. Previously, we had demonstrated that BBR alleviated the inflammatory response in adjuvant-induced arthritis (AA) rats by regulating polarization of macrophages. However, the exact mechanics by which BBR regulates macrophage polarization remained unclear. Here, we showed that BBR treatment had little influence on total number of macrophages in joints of AA rats, but increased the proportion of M2 macrophages and decreased the proportion of M1 macrophages. Meanwhile, we found BBR up-regulated the expression of AMP-activated protein kinase phosphorylation (p-AMPK) and down-regulated the expression of Hypoxia inducible factor 1α (HIF-1α) in synovial macrophages of AA rats. In vitro, using LPS-stimulated peritoneal macrophages from normal rats, we also verified that pretreatment with BBR promoted transition from M1 to M2 by up-regulating the expression of p-AMPK and suppressing the expression of HIF-1α. Compound C (an AMPK inhibitor) could abrogate the inhibition of BBR on migration of macrophages. Glycolysis of M1 suppressed by BBR through decreasing lactate export, glucose consumption, and increasing intracellular ATP content, which was remarkably reversed by Compound C. These findings indicated that anti-arthritis effect of BBR is associated with regulating energy metabolism of macrophages through AMPK/HIF-1α pathway.

Diabetes aggravates myocardial ischaemia reperfusion injury via activating Nox2-related programmed cell death in an AMPK-dependent manner

Cardiovascular diseases such as myocardial ischaemia have a high fatality rate in patients with diabetes. This study was designed to expose the crosstalk between oxidative stress and AMPK, a vital molecule that controls biological energy metabolism, in myocardial ischaemia reperfusion injury (I/RI) in diabetic rats. Diabetes was stimulated in rats using streptozotocin injection. Rats were separated on random into control, control + I/R, Diabetes, Diabetes + I/R, Diabetes + I/R + N-acetylcysteine and Diabetes + I/R + Vas2870 groups. Myocardial infarct size was determined, and the predominant Nox family isoforms were analysed. In vitro, the H9C2 cells were administered excess glucose and exposed to hypoxia/reoxygenation to mimic diabetes and I/R. The AMPK siRNA or AICAR was used to inhibit or activate AMPK expression in H9C2 cells, respectively. Then, myocardial oxidative stress and programmed cell death were measured. Diabetes or high glucose levels were found to aggravate myocardial I/RI or hypoxia/reoxygenation in H9C2 cells, as demonstrated by an increase in myocardial infarct size or lactate dehydrogenase levels, oxidative stress generation and induction of programmed cell death. In diabetic rat hearts, cardiac Nox1, Nox2 and Nox4 were all heightened. The suppression of Nox2 expression using Vas2870 or Nox2-siRNA treatment in vivo or in vitro, respectively, protected diabetic rats from myocardial I/RI. AMPK gene knockout increased Nox2 protein expression while AMPK agonist decreased Nox2 expression. Therefore, diabetes aggravates myocardial I/RI by generating of Nox2-associated oxidative stress in an AMPK-dependent manner, which led to the induction of programmed cell death such as apoptosis, pyroptosis and ferroptosis.

Interactions Between Tumor Biology and Targeted Nanoplatforms for Imaging Applications

Although considerable efforts have been conducted to diagnose, improve, and treat cancer in the past few decades, existing therapeutic options are insufficient, as mortality and morbidity rates remain high. Perhaps the best hope for substantial improvement lies in early detection. Recent advances in nanotechnology are expected to increase the current understanding of tumor biology, and will allow nanomaterials to be used for targeting and imaging both in vitro and in vivo experimental models. Owing to their intrinsic physicochemical characteristics, nanostructures (NSs) are valuable tools that have received much attention in nanoimaging. Consequently, rationally designed NSs have been successfully employed in cancer imaging for targeting cancer-specific or cancer-associated molecules and pathways. This review categorizes imaging and targeting approaches according to cancer type, and also highlights some new safe approaches involving membrane-coated nanoparticles, tumor cell-derived extracellular vesicles, circulating tumor cells, cell-free DNAs, and cancer stem cells in the hope of developing more precise targeting and multifunctional nanotechnology-based imaging probes in the future.

Down-regulation of AMPK signaling pathway rescues hearing loss in TFB1 transgenic mice and delays age-related hearing loss

AMP-activated protein kinase (AMPK) integrates the regulation of cell growth and metabolism. AMPK activation occurs in response to cellular energy decline and mitochondrial dysfunction triggered by reactive oxygen species (ROS). In aged Tg-mtTFB1 mice, a mitochondrial deafness mouse model, hearing loss is accompanied with cochlear pathology including reduced endocochlear potential (EP) and loss of spiral ganglion neurons (SGN), inner hair cell (IHC) synapses and outer hair cells (OHC). Accumulated ROS and increased apoptosis signaling were also detected in cochlear tissues, accompanied by activation of AMPK. To further explore the role of AMPK signaling in the auditory phenotype, we used genetically knocked out AMPKα1 as a rescue to Tg-mtTFB1 mice and observed: improved ABR wave I, EP and IHC function, normal SGNs, IHC synapses morphology and OHC survivals, with decreased ROS, reduced pro-apoptotic signaling (Bax) and increased anti-apoptotic signaling (Bcl-2) in the cochlear tissues, indicating that reduced AMPK attenuated apoptosis via ROS-AMPK-Bcl2 pathway in the cochlea. To conclude, AMPK hyperactivation causes accelerated presbycusis in Tg-mtTFB1 mice by redox imbalance and dysregulation of the apoptosis pathway. The effects of AMPK downregulation on pro-survival function and reduction of oxidative stress indicate AMPK serves as a target to rescue or relieve mitochondrial hearing loss.

Regulation of autophagy and apoptosis by Dp44mT-mediated activation of AMPK in pancreatic cancer cells

Upon activation, the 5'-adenosine monophosphate-activated protein kinase (AMPK) increases catabolism, while inhibiting anabolism. The anti-cancer agent, di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), activates AMPK in multiple tumor cell-types (Biochim. Biophys Acta 2016;1863:2916-2933). This acts as an initial cell "rescue response" after iron-depletion mediated by Dp44mT. Considering Dp44mT-mediated AMPK activation, the role of AMPK on Dp44mT cytotoxicity was examined. Dp44mT increased the p-AMPK/AMPK ratio in multiple tumor cell-types over short (24 h) and longer (72 h) incubations. Notably, Dp44mT was more effective in inhibiting tumor cell proliferation after AMPK silencing, potentially due to the loss of AMPK-mediated metabolic plasticity that protects cells against Dp44mT cytotoxicity. The silencing of AMPK-increased cellular cholesterol and stabilized lysosomes against Dp44mT-mediated lysosomal membrane permeabilization. This was substantiated by studies demonstrating that the cholesterol-depleting agent, methyl-β-cyclodextrin (MβCD), restores Dp44mT-mediated lysosomal membrane permeabilization in AMPK silenced cells. The increased levels of cholesterol after AMPK silencing were independent of the ability of AMPK to inhibit the rate-limiting step of cholesterol synthesis via the inactivating phosphorylation of 3-hydroxy-3-methylglutaryl CoA reductase (HMGCR) at Ser872. In fact, Dp44mT did not increase phosphorylation of HMGCR at (Ser872), but decreased total HMGCR expression similarly in both the presence or absence of AMPK silencing. Dp44mT was demonstrated to increase autophagic initiation after AMPK silencing via an AMPK- and Beclin-1-independent mechanism. Further, there was increased cleaved caspase 3 and cleaved PARP after incubation of AMPK silenced cells with Dp44mT. Overall, AMPK silencing promotes Dp44mT anti-proliferative activity, suggesting a role for AMPK in rescuing its cytotoxicity by inhibiting autophagy and also apoptosis.

Effect of Age and Lipoperoxidation in Rat and Human Adipose Tissue-Derived Stem Cells

A wide range of clinical applications in regenerative medicine were opened decades ago with the discovery of adult stem cells. Highly promising adult stem cells are mesenchymal stem/stromal cells derived from adipose tissue (ADSCs), primarily because of their abundance and accessibility. These cells have multipotent properties and have been used extensively to carry out autologous transplants. However, the biology of these cells is not entirely understood. Among other factors, the regeneration capacity of these cells will depend on both their capacity of proliferation/differentiation and the robustness of the biochemical pathways that allow them to survive under adverse conditions like those found in damaged tissues. The transcription factors, such as Nanog and Sox2, have been described as playing an important role in stem cell proliferation and differentiation. Also, the so-called longevity pathways, in which AMPK and SIRT1 proteins play a crucial role, are essential for cell homeostasis under stressful situations. These pathways act by inhibiting the translation through downregulation of elongation factor-2 (eEF2). In order to deepen knowledge of mesenchymal stem cell biology and which factors are determinant in the final therapeutic output, we evaluate in the present study the levels of all of these proteins in the ADSCs from humans and rats and how these levels are affected by aging and the oxidative environment. Due to the effect of aging and oxidative stress, our results suggest that before performing a cell therapy with ADSCs, several aspects reported in this study such as oxidative stress status and proliferation and differentiation capacity should be assessed on these cells. This would allow us to know the robustness of the transplanted cells and to predict the therapeutic result, especially in elder patients, where probably ADSCs do not carry out their biological functions in an optimal way.

Catestatin in defense of oxidative-stress-induced apoptosis: A novel mechanism by activating the beta2 adrenergic receptor and PKB/Akt pathway in ischemic-reperfused myocardium

Apoptosis induced by oxidative stress is one of the most important cardiomyocytes losses during ischemia-reperfusion (I/R). Catestatin (CST) has been demonstrated to have the anti-oxidative capacity in vitro. We hypothesized that CST intervention could reduce apoptosis of cardiomyocytes induced by oxidative stress in I/R. In Langendorff-perfused rat heart global I/R model, CST was introduced at the reperfusion stage. In comparison to the control group, CST led to preservation on activities of superoxide dismutase and glutathione peroxidase, improvement of hemodynamics, and reduced infarction area in reperfused myocardium. The protection of CST was also shown by less apoptotic cardiomyocytes in TUNEL staining, less caspase-3 activation, and increased phosphorylation of protein kinase B (PKB/Akt) in Western blot. To further demonstrate the benefits of CST and explore the possible underlying mechanism, H₂O₂-challenged primary-cultured neonatal rat cardiomyocytes were used to simulate the oxidative-stressed scenario. CST incubation with the H₂O₂-challenged cardiomyocytes led to reduction of apoptosis, which was demonstrated by less Hoechst 33342 positive staining of nuclei, less caspase-3 activation, and DNA fragmentation. The effect of CST was abrogated by pretreatment of the cardiomyocytes with the PI3K inhibitor LY294002. Furthermore, Akt activation and the anti-apoptosis effect of CST were abolished by pretreatment of the cardiomyocytes with β2 receptor inhibitor ICI118551. Thus, the salvage of oxidative-stress-induced apoptotic cardiomyocytes in I/R by CST might involve activation β2 receptor and regulation of PI3K/Akt signaling in reperfusion injury salvage kinase (RISK) pathway.

Anti-inflammatory Property of AMP-activated Protein Kinase

BACKGROUND

One of the many debated topics in inflammation research is whether this scenario is really an accelerated form of human wound healing and immunityboosting or a push towards autoimmune diseases. The answer requires a better understanding of the normal inflammatory process, including the molecular pathology underlying the possible outcomes. Exciting recent investigations regarding severe human inflammatory disorders and autoimmune conditions have implicated molecular changes that are also linked to normal immunity, such as triggering factors, switching on and off, the influence of other diseases and faulty stem cell homeostasis, in disease progression and development.

METHODS

We gathered around and collected recent online researches on immunity, inflammation, inflammatory disorders and AMPK. We basically searched PubMed, Scopus and Google Scholar to assemble the studies which were published since 2010.

RESULTS

Our findings suggested that inflammation and related disorders are on the verge and interfere in the treatment of other diseases. AMPK serves as a key component that prevents various kinds of inflammatory signaling. In addition, our table and hypothetical figures may open a new door in inflammation research, which could be a greater therapeutic target for controlling diabetes, obesity, insulin resistance and preventing autoimmune diseases.

CONCLUSION

The relationship between immunity and inflammation becomes easily apparent. Yet, the essence of inflammation turns out to be so startling that the theory may not be instantly established and many possible arguments are raised for its clearance. However, this study might be able to reveal some possible approaches where AMPK can reduce or prevent inflammatory disorders.

Matrine attenuates oxidative stress and cardiomyocyte apoptosis in doxorubicin-induced cardiotoxicity via maintaining AMPKα/UCP2 pathway

Oxidative stress and cardiomyocyte apoptosis are involved in the pathogenesis of doxorubicin (DOX)-induced cardiotoxicity. Matrine is well-known for its powerful anti-oxidant and anti-apoptotic capacities. Our present study aimed to investigate the effect of matrine on DOX-induced cardiotoxicity and try to unearth the underlying mechanisms. Mice were exposed with DOX to generate DOX-induced cardiotoxicity or normal saline as control. H9C2 cells were used to verify the effect of matrine in vitro. DOX injection triggered increased generation of reactive oxygen species (ROS) and excessive cardiomyocyte apoptosis, which were significantly mitigated by matrine. Mechanistically, we found that matrine ameliorated DOX-induced uncoupling protein 2 (UCP2) downregulation, and UCP2 inhibition by genipin could blunt the protective effect of matrine on DOX-induced oxidative stress and cardiomyocyte apoptosis. Besides, 5'-AMP-activated protein kinase α2 (Ampkα2) deficiency inhibited matrine-mediated UCP2 preservation and abolished the beneficial effect of matrine in mice. Besides, we observed that matrine incubation alleviated DOX-induced H9C2 cells apoptosis and oxidative stress level via activating AMPKα/UCP2, which were blunted by either AMPKα or UCP2 inhibition with genetic or pharmacological methods. Matrine attenuated oxidative stress and cardiomyocyte apoptosis in DOX-induced cardiotoxicity via maintaining AMPKα/UCP2 pathway, and it might be a promising therapeutic agent for the treatment of DOX-induced cardiotoxicity.

Co-Delivery of Metformin Enhances the Antimultidrug Resistant Tumor Effect of Doxorubicin by Improving Hypoxic Tumor Microenvironment

Doxorubicin (DOX) is a first-line chemo drug for cancer therapy, yet it fails to treat multi-drug-resistant tumors. Hypoxia is a major causative factor leading to chemotherapy failure. Particularly, hypoxia up-regulates its responsive transcription factor-hypoxia-inducible factors (HIF)-to induce the overexpression of drug resistant genes. Metformin (MET) is recently found to cooperate with DOX against multiple tumors. As a mitochondrial inhibitor, MET could suppress tumor oxygen consumption, and thereby modulate the hypoxic tumor microenvironment. In this study, we used cationic liposomes to codeliver both DOX and MET for treating multi-drug-resistant breast cancer cells-MCF7/ADR. Faster release of MET enhanced the cytotoxicity of DOX through attenuating hypoxic stress both in vivo and in vitro. MET diminished the cellular oxygen consumption and inhibited HIF1α and P-glycoprotein (Pgp) expression in vitro. In addition, the dual-drug-loaded liposomes increased tumor targeting and intratumoral blood oxygen saturation, which suggested that the tumor reoxygenation effect of MET facilitated the exertion of its synergistic activity with DOX against MCF7/ADR xenografts. In general, our study represents a feasible strategy to boost the therapeutic effect in treating multi-drug-resistant cancer by improving the hypoxic tumor microenvironment.

Cancer Stem Cells in Neuroblastoma: Expanding the Therapeutic Frontier

Neuroblastoma (NB) is the most common extracranial solid tumor often diagnosed in childhood. Despite intense efforts to develop a successful treatment, current available therapies are still challenged by high rates of resistance, recurrence and progression, most notably in advanced cases and highly malignant tumors. Emerging evidence proposes that this might be due to a subpopulation of cancer stem cells (CSCs) or tumor-initiating cells (TICs) found in the bulk of the tumor. Therefore, the development of more targeted therapy is highly dependent on the identification of the molecular signatures and genetic aberrations characteristic to this subpopulation of cells. This review aims at providing an overview of the key molecular players involved in NB CSCs and focuses on the experimental evidence from NB cell lines, patient-derived xenografts and primary tumors. It also provides some novel approaches of targeting multiple drivers governing the stemness of CSCs to achieve better anti-tumor effects than the currently used therapeutic agents.

Metformin-induced autophagy and irisin improves INS-1 cell function and survival in high-glucose environment via AMPK/SIRT1/PGC-1α signal pathway

In order to explore the protective function of metformin on pancreatic β cells to alleviate insulin resistance and underlying mechanisms, INS-1 cells were cultured into normal control (N), high glucose (H), high glucose and metformin (H + Met), high glucose and chloroquine (H + CQ), and high glucose and Ex527 (H + Ex527) groups, respectively. Upon 24-hr cultivation, the proliferation and glucose-stimulated insulin secretion (GSIS) of INS-1 cells were determined, and the expression of irisin and other proteins associated with AMPK/SIRT1/PGC-1α signal pathway, autophagy, and apoptosis was evaluated. Compared with the N group, the cells from the H group revealed lower proliferation, GSIS, and expression of irisin and proteins associated with AMPK/SIRT1/PGC-1α signal pathway and autophagy, but higher expression of proteins associated with apoptosis; in contrast, metformin could significantly rescue lower cell proliferation, GSIS, and expression of proteins associated with AMPK/SIRT1/PGC-1α signal pathway and autophagy, as well as irisin, and suppress apoptosis in high-glucose environment. Meanwhile, autophagy inhibitor CQ and SIRT1 inhibitor Ex527 can block above functions of metformin. Therefore, metformin can promote INS-1 cell proliferation, enhance GSIS, and suppress apoptosis by activating AMPK/SIRT1/PGC-1α signal pathway, up-regulating irisin expression, and inducing autophagy in INS-1 cells in high-glucose environment.

Cordycepin promotes browning of white adipose tissue through an AMP-activated protein kinase (AMPK)-dependent pathway

Obesity is a worldwide epidemic. Promoting browning of white adipose tissue (WAT) contributes to increased energy expenditure and hence counteracts obesity. Here we show that cordycepin (Cpn), a natural derivative of adenosine, increases energy expenditure, inhibits weight gain, improves metabolic profile and glucose tolerance, decreases WAT mass and adipocyte size, and enhances cold tolerance in normal and high-fat diet-fed mice. Cpn markedly increases the surface temperature around the inguinal WAT and turns the inguinal fat browner. Further investigations show that Cpn induces the development of brown-like adipocytes in inguinal and, to a less degree, epididymal WAT depots. Cpn also increases the expression of uncoupling protein 1 (UCP1) and other thermogenic genes in WAT and 3T3-L1 differentiated adipocytes, in which AMP-activated protein kinase (AMPK) plays an important role. Our results provide novel insights into the function of Cpn in regulating energy balance, and suggest a potential utility of Cpn in the treatment of obesity.

Mitochondrial uncoupler BAM15 inhibits artery constriction and potently activates AMPK in vascular smooth muscle cells

Our previous studies found that mitochondrial uncouplers CCCP and niclosamide inhibited artery constriction and the mechanism involved AMPK activation in vascular smooth muscle cells. BAM15 is a novel type of mitochondrial uncoupler. The aim of the present study is to identify the vasoactivity of BAM15 and characterize the BAM15-induced AMPK activation in vascular smooth muscle cells (A10 cells). BAM15 relaxed phenylephrine (PE)-induced constricted rat mesenteric arteries with intact and denuded endothelium. Pretreatment with BAM15 inhibited PE-induced constriction of rat mesenteric arteries with intact and denuded endothelium. BAM15, CCCP, and niclosamide had the comparable IC₅₀ value of vasorelaxation in PE-induced constriction of rat mesenteric arteries. BAM15 was less cytotoxic in A10 cells compared with CCCP and niclosamide. BAM15 depolarized mitochondrial membrane potential, induced mitochondrial fission, increased mitochondrial ROS production, and increased mitochondrial oxygen consumption rate in A10 cells. BAM15 potently activated AMPK in A10 cells and the efficacy of BAM15 was stronger than that of CCCP, niclosamide, and AMPK positive activators metformin and AICAR. In conclusion, BAM15 activates AMPK in vascular smooth muscle cells with higher potency than that of CCCP, niclosamide and the known AMPK activators metformin and AICAR. The present work indicates that BAM15 is a potent AMPK activator.

Paeoniflorin attenuates atRAL-induced oxidative stress, mitochondrial dysfunction and endoplasmic reticulum stress in retinal pigment epithelial cells via triggering Ca2+/CaMKII-dependent activation of AMPK

Abnormal accumulation of the free-form all-trans-retinal (atRAL), a major intermediate of human visual cycle, is considered to be a key cause of retinal pigment epithelial (RPE) dysfunction in the pathogenesis of retinal degenerative diseases such as age-related macular degeneration (AMD). Paeoniflorin (PF), a monoterpene glucoside isolated from Paeonia lactiflora Pall., has been used in clinical treatment of retinal degenerative diseases in China for several years; however, the underlying mechanism remains unclear. The aim of this study is to investigate the protective effect of PF against atRAL toxicity in human ARPE-19 cells and its molecular mechanism. The results of our study showed that the pre-treatment of PF dose-dependently attenuated atRAL-induced cell injury by the reduction of Nox1/ROS-associated oxidative stress, mitochondrial dysfunction and GRP78-PERK-eIF2α-ATF4-CHOP-regulated endoplasmic reticulum (ER) stress in ARPE-19 cells. Additionally, our data showed that PF mainly exerted its activity via triggering calcium-calmodulin dependent protein kinase II (CaMKII)-mediated activation of AMP-activated protein kinase (AMPK). AMPK inhibition significantly reversed the protective effect of PF against atRAL toxicity in ARPE-19 cells. Overall, our findings provided the novel mechanism of PF protecting human RPE cells, which may prevent the progression of retinal degenerative diseases.

Implications of AMPK in the Formation of Epithelial Tight Junctions

Tight junctions (TJ) play an essential role in the epithelial barrier. By definition, TJ are located at the demarcation between the apical and baso-lateral domains of the plasma membrane in epithelial cells. TJ fulfill two major roles: (i) TJ prevent the mixing of membrane components; and (ii) TJ regulate the selective paracellular permeability. Disruption of TJ is regarded as one of the earliest hallmarks of epithelial injury, leading to the loss of cell polarity and tissue disorganization. Many factors have been identified as modulators of TJ assembly/disassembly. More specifically, in addition to its role as an energy sensor, adenosine monophosphate-activated protein kinase (AMPK) participates in TJ regulation. AMPK is a ubiquitous serine/threonine kinase composed of a catalytic α-subunit complexed with regulatory β-and γ-subunits. AMPK activation promotes the early stages of epithelial TJ assembly. AMPK phosphorylates the adherens junction protein afadin and regulates its interaction with the TJ-associated protein zonula occludens (ZO)-1, thereby facilitating ZO-1 distribution to the plasma membrane. In the present review, we detail the signaling pathways up-and down-stream of AMPK activation at the time of Ca2+-induced TJ assembly.

Understanding mitochondrial biogenesis through energy sensing pathways and its translation in cardio-metabolic health

Mitochondria play a pivotal role in physiological energy governance. Mitochondrial biogenesis comprises growth and division of pre-existing mitochondria, triggered by environmental stressors such as endurance exercise, caloric restriction, cold exposure and oxidative stress. For normal physiology, balance between energy intake, storage and expenditure is of utmost important for the coordinated regulation of energy homeostasis. In contrast, abnormalities in these regulations render the individual susceptible to cardiometabolic disorders. This review provides a comprehensive coverage and understanding on mitochondrial biogenesis achieved through energy-sensing pathways. This includes the complex coordination of nuclear, cytosolic and mitochondrial events involving energy sensors, transcription factors, coactivators and regulators. It focuses on the importance of mitochondrial biogenesis in cardiometabolic health. Lastly, converging on the benefits of caloric restriction and endurance exercise in achieving cardiometabolic health.