Activation of autophagy by globular adiponectin attenuates ethanol-induced apoptosis in HepG2 cells: involvement of AMPK/FoxO3A axis

FGF21 agonists: An emerging therapeutic for metabolic dysfunction-associated steatohepatitis and beyond

The worldwide epidemics of obesity, hypertriglyceridemia, dyslipidaemia, type 2 diabetes, and metabolic dysfunction-associated steatotic liver disease (MASLD)/metabolic dysfunction-associated steatohepatitis (MASH) represent a major economic burden on healthcare systems. Patients with at-risk MASH, defined as MASH with moderate or significant fibrosis, are at higher risk of comorbidity/mortality, with a significant risk of cardiovascular diseases and/or major adverse liver outcomes. Despite a high unmet medical need, there is only one drug approved for MASH. Several drug candidates have reached the phase III development stage and could lead to several potential conditional drug approvals in the coming years. Within the armamentarium of future treatment options, FGF21 analogues hold an interesting position thanks to their pleiotropic effects in addition to their significant effect on both MASH resolution and fibrosis improvement. In this review, we summarise preclinical and clinical data from FGF21 analogues for MASH and explore additional potential therapeutic indications.

AMPK/autophagy-mediated alleviation of tendinopathy by IL-38: A novel strategy for the treatment of obesity-related tendinopathy

The effect of interleukin-38 (IL-38), a recently identified member of the IL-1 family with potential applications in various inflammation-related conditions, on ER stress has not been explored. Furthermore, its role in obesity-associated tendinopathy has not been investigated. In this study, human primary tenocytes were treated with palmitate (200 or 400 μM) and palmitate plus IL-38 (0-50 ng/mL) for 24 h. Western blotting was used to assess ER stress and tendinopathogenic markers in tenocytes. Monodansylcadaverine (MDC) staining was used to evaluate autophagosomes. Apoptosis was determined by cell viability assays, caspase 3 activity assays and TUNEL assays. Cell migration was evaluated by a cell scratch assay. Small interfering (si) RNA transfection was used for target gene silencing. Treatment of tenocytes with IL-38 attenuated apoptosis, restored the balance between MMPs and TIMP-1, and alleviated ER stress under palmitate conditions. IL-38 treatment enhanced AMPK phosphorylation and promoted the expression of autophagy markers related to LC3 conversion, p62 degradation, and autophagosome formation in cultured tenocytes. The effects of IL-38 on ER stress, apoptosis, and MMP-9, MMP-13, and TIMP-1 expression in palmitate-treated tenocytes were abrogated by AMPK siRNA or 3-methyladenine (3MA). These results suggest that IL-38 alleviates ER stress through the AMPK/autophagy pathway, thereby reducing apoptosis and preventing extracellular matrix (ECM) degradation in tenocytes under hyperlipidemic conditions. This study provides a promising therapeutic avenue for treating obesity-related tendinopathy using an endogenous compound such as IL-38.

Pathogenic mechanisms and regulatory factors involved in alcoholic liver disease

Alcoholism is a widespread and damaging behaviour of people throughout the world. Long-term alcohol consumption has resulted in alcoholic liver disease (ALD) being the leading cause of chronic liver disease. Many metabolic enzymes, including alcohol dehydrogenases such as ADH, CYP2E1, and CATacetaldehyde dehydrogenases ALDHsand nonoxidative metabolizing enzymes such as SULT, UGT, and FAEES, are involved in the metabolism of ethanol, the main component in alcoholic beverages. Ethanol consumption changes the functional or expression profiles of various regulatory factors, such as kinases, transcription factors, and microRNAs. Therefore, the underlying mechanisms of ALD are complex, involving inflammation, mitochondrial damage, endoplasmic reticulum stress, nitrification, and oxidative stress. Moreover, recent evidence has demonstrated that the gut-liver axis plays a critical role in ALD pathogenesis. For example, ethanol damages the intestinal barrier, resulting in the release of endotoxins and alterations in intestinal flora content and bile acid metabolism. However, ALD therapies show low effectiveness. Therefore, this review summarizes ethanol metabolism pathways and highly influential pathogenic mechanisms and regulatory factors involved in ALD pathology with the aim of new therapeutic insights.

Role of FOXO3a Transcription Factor in the Regulation of Liver Oxidative Injury

Oxidative stress has been identified as a key mechanism in liver damage caused by various chemicals. The transcription factor FOXO3a has emerged as a critical regulator of redox imbalance. Multiple post-translational changes and epigenetic processes closely regulate the activity of FOXO3a, resulting in synergistic or competing impacts on its subcellular localization, stability, protein-protein interactions, DNA binding affinity, and transcriptional programs. Depending on the chemical nature and subcellular context, the oxidative-stress-mediated activation of FOXO3a can induce multiple transcriptional programs that play crucial roles in oxidative injury to the liver by chemicals. Here, we mainly review the role of FOXO3a in coordinating programs of genes that are essential for cellular homeostasis, with an emphasis on exploring the regulatory mechanisms and potential application of FOXO3a as a therapeutic target to prevent and treat liver oxidative injury.

Pre-Ischemic Hypothermic Oxygenated Perfusion Alleviates Protective Molecular Markers of Ischemia-Reperfusion Injury in Rat Liver

To expand the pool of organs, hypothermic oxygenated perfusion (HOPE), one of the most promising perfusion protocols, is currently performed after cold storage (CS) at transplant centers (HOPE-END). We investigated a new timing for HOPE, hypothesizing that performing HOPE before CS (HOPE-PRE) could boost mitochondrial protection allowing the graft to better cope with the accumulation of oxidative stress during CS. We analyzed liver injuries at 3 different levels. Histologic analysis demonstrated that, compared to classical CS (CTRL), the HOPE-PRE group showed significantly less ischemic necrosis compared to CTRL vs HOPE-END. From a biochemical standpoint, transaminases were lower after 2 hours of reperfusion in the CTRL vs HOPE-PRE group, which marked decreased liver injury. qPCR analysis on 37 genes involved in ischemia-reperfusion injury revealed protection in HOPE-PRE and HOPE-END compared to CTRL mediated through similar pathways. However, the CTRL vs HOPE-PRE group demonstrated an increased transcriptional level for protective genes compared to the CTRL vs HOPE-END group. This study provides insights on novel biomarkers that could be used in the clinic to better characterize graft quality improving transplantation outcomes.

Protective effects of AdipoRon on the liver of Huoyan goose fed a high-fat diet

Adiponectin can participate in the regulation of glucose and lipid metabolism, energy regulation, immune response, resistance to inflammation, oxidative stress, and apoptosis. Studies in rodents demonstrated that the small molecule compound adiponectin receptor agonist AdipoRon could activate the adiponectin receptor and played the same biological role as adiponectin. To explore the influence and regulation of AdipoRon on lipid metabolism disorder in Huoyan goose liver, in this study, goslings were fed a high-fat diet and then administered different dosages of AdipoRon. Subsequently, goose body weight, liver index, liver histopathological changes, blood glucose, blood and liver lipid, biochemical indexes related to liver function and oxidative stress, and the expression levels of genes related to lipid metabolism, inflammation, apoptosis, and autophagy, adiponectin and its receptors, key molecules of adiponectin involved signal pathway, and transcription factors in the liver, were detected using H&E and Oil red O staining, ELISA, and qRT-PCR methods. The results indicated that AdipoRon could alter the expression of lipid metabolism-related genes, inflammatory factors, apoptosis and autophagy genes, and adiponectin and its receptor genes in liver tissues through signaling pathways such as AMPK and p38 MAPK, as well as the involvement of transcription factors such as PPARα, PPARγ, SIRT1, and FOXO1, reduce the lipid content in blood and liver tissues of geese fed high-fat diets, improve liver antioxidant capacity, regulate apoptosis and autophagy of hepatocytes, and reduce liver inflammatory injury. Our study suggests that AdipoRon has a protective effect on fatty liver injury in goslings fed a high-fat diet.

Cx32 promotes autophagy and produces resistance to SN‑induced apoptosis via activation of AMPK signalling in cervical cancer

The roles of gap junctions (GJs) and its components, connexins, in the autophagy of cervical cancer cells have been rarely investigated. Our previous study demonstrated that connexin 32 (Cx32) exerted an anti‑apoptotic effect on cervical cancer. However, as an important regulator of apoptosis, whether the autophagy is involved in the function of Cx32 on cervical cancer cells is not well defined. The present study aimed to investigate the role of Cx32 on autophagy and apoptosis inhibition in cervical cancer cells. The expression levels of Cx32 and the autophagy‑associated protein LC3‑Ⅱ in paracancerous cervical tissues (n=30) and cervical cancer (n=50) tissues were determined via western blotting. In total, 45 cervical cancer specimens were used to evaluate the clinical relevance of Cx32 and LC3‑Ⅱ. It was found that both Cx32 and LC3‑Ⅱ were upregulated in cervical cancer tissues compared with those in paracancerous cervical tissues. The effect of Cx32 on autophagy was examined by detecting the change of LC3‑Ⅱ using western blotting, transfection with enhanced green fluorescent protein‑LC3 plasmid and transmission electron microscopy analysis. Overexpression of Cx32 significantly enhanced autophagy in HeLa‑Cx32 cells, whereas knockdown of Cx32 suppressed autophagy in C‑33A cells. The flow cytometry results demonstrated that Cx32 inhibited the apoptosis of cervical cancer cells by promoting autophagy. Moreover, Cx32 triggered autophagy via the activation of the AMP‑activated protein kinase (AMPK) signalling, regardless of the presence or absence of GJs. Collectively, it was identified that Cx32 exerted its anti‑apoptotic effect by activating autophagy via the AMPK pathway in cervical cancer, which demonstrates a novel mechanism for Cx32 in human cervical cancer progression.

Blockade of Uttroside B-Induced Autophagic Pro-Survival Signals Augments Its Chemotherapeutic Efficacy Against Hepatocellular Carcinoma

Our previous study has demonstrated that Uttroside B (Utt-B), a saponin isolated from the leaves of Solanum nigrum Linn induces apoptosis in hepatic cancer cells and exhibits a remarkable growth inhibition of Hepatocellular Carcinoma (HCC). Our innovation has been granted a patent from the US (US 2019/0160088A1), Canada (3,026,426.), Japan (JP2019520425) and South Korea (KR1020190008323) and the technology have been transferred commercially to Q Biomed, a leading US-based Biotech company. Recently, the compound received approval as 'Orphan Drug' against HCC from US FDA, which reveals the clinical relevance of evaluating its antitumor efficacy against HCC. In the present study, we report that Utt-B promotes pro-survival autophagy in hepatic cancer cells as evidenced by the increased expression of autophagy-related proteins, including LC3-II, Beclin1, ATG 5, and ATG 7, as well as a rise in the autophagic flux. Hence, we investigated whether Utt-B-induced autophagic response is complementing or contradicting its apoptotic program in HCC. Inhibition of autophagy using the pharmacological inhibitors, Bafilomycin A1(Baf A1), and 3-methyl adenine (3-MA), and the biological inhibitor, Beclin1 siRNA, significantly enhances the apoptosis of hepatic cancer cells and hence the cytotoxicity induced by Utt-B. We also found increased expression of autophagy markers in Utt-B-treated xenografts derived from HCC. We further analyzed whether the antimalarial drug, Chloroquine (Cqn), a well-known autophagy inhibitor, can enhance the anticancer effect of Utt-B against HCC. We found that inhibition of autophagy using Cqn significantly enhances the antitumor efficacy of Utt-B in vitro and in vivo, in NOD SCID mice bearing HCC xenografts. Taken together, our results suggest that the antitumor effect of Utt-B against HCC can be further enhanced by blocking autophagy. Furthermore, Utt-B in combination with Cqn, a clinically approved drug, if repurposed and used in a combinatorial regimen with Utt-B, can further improve the therapeutic efficacy of Utt-B against HCC.

Adiponectin up-regulates the decrease of myocardial autophagic flux induced by β1 -adrenergic receptor autoantibody partly dependent on AMPK

Cardiomyocytes autophagy is essential for maintaining cardiac function. Our previous studies have found that β₁‐adrenergic receptor autoantibody (β₁‐AA) induced the decreased myocardial autophagic flux, which resulted in cardiomyocyte death and cardiac dysfunction. And other studies demonstrated that β₁‐AA induced the decrease of AMPK phosphorylation, the key hub of autophagy pathway, while adiponectin up‐regulated autophagic flux mediated by AMPK. However, it is not clear whether adiponectin improves the inhibition of myocardial autophagic flux induced by β₁‐AA by up‐regulating the level of AMPK phosphorylation. In this study, it has been confirmed that β₁‐AA induced the decrease of AMPK phosphorylation level in both vivo and vitro. Moreover, pretreatment of cardiomyocytes with AMPK inhibitor Compound C could further reduce the autophagic flux induced by β₁‐AA. Adiponectin deficiency could aggravate the decrease of myocardial AMPK phosphorylation level, autophagic flux and cardiac function induced by β₁‐AA. Further, exogenous adiponectin could reverse the decline of AMPK phosphorylation level and autophagic flux induced by β₁‐AA and even reduce cardiomyocyte death. While pretreated with the Compound C, the adiponectin treatment did not improve the decreased autophagosome formation, but still improved the decreased autophagosome clearance induced by β₁‐AA in cardiomyocytes. This study is the first time to confirm that β₁‐AA could inhibit myocardial autophagic flux by down‐regulating AMPK phosphorylation level. Adiponectin could improve the inhibition of myocardial autophagic flux induced by β₁‐AA partly dependent on AMPK, so as to provide an experimental basis for the treatment of patients with β₁‐AA‐positive cardiac dysfunction.

Emerging Roles of Impaired Autophagy in Fatty Liver Disease and Hepatocellular Carcinoma

Autophagy is a conserved catabolic process that eliminates dysfunctional cytosolic biomolecules through vacuole-mediated sequestration and lysosomal degradation. Although the molecular mechanisms that regulate autophagy are not fully understood, recent work indicates that dysfunctional/impaired autophagic functions are associated with the development and progression of nonalcoholic fatty liver disease (NAFLD), alcoholic fatty liver disease (AFLD), and hepatocellular carcinoma (HCC). Autophagy prevents NAFLD and AFLD progression through enhanced lipid catabolism and decreasing hepatic steatosis, which is characterized by the accumulation of triglycerides and increased inflammation. However, as both diseases progress, autophagy can become impaired leading to exacerbation of both pathological conditions and progression into HCC. Due to the significance of impaired autophagy in these diseases, there is increased interest in studying pathways and targets involved in maintaining efficient autophagic functions as potential therapeutic targets. In this review, we summarize how impaired autophagy affects liver function and contributes to NAFLD, AFLD, and HCC progression. We will also explore how recent discoveries could provide novel therapeutic opportunities to effectively treat these diseases.

Metformin Attenuates ROS via FOXO3 Activation in Immune Cells

Forkhead box O 3 (FOXO3) is a transcription factor involved in cell metabolism, inflammation and longevity. Here, we investigated if metformin can activate FOXO3 in human immune cells and affects the subsequent level of reactive oxygen/nitrogen species (ROS/RNS) in immune cells. AMP-activated protein kinase (AMPK) and FOXO3 activation were investigated by immunoblot or flow cytometry (FC) analysis, respectively. FOXO3 target gene expression was quantified by real-time PCR. ROS/RNS measurement using dichlorodihydrofluorescein diacetate (DCFH-DA) dye was investigated by FC. The role of the FOXO3 single nucleotide polymorphisms (SNPs) rs12212067, rs2802292 and rs12206094 on ROS/RNS production was studied using allelic discrimination PCR. Metformin induced activation of AMPK (pT172) and FOXO3 (pS413). ROS/RNS level was reduced in immune cells after metformin stimulation accompanied by induction of the FOXO3 targets mitochondrial superoxide dismutase and cytochrome c. Studies in Foxo3 deficient (Foxo3-/- ) mouse splenocytes confirmed that metformin mediates its effects via Foxo3 as it attenuates ROS/RNS in myeloid cells of wildtype (WT) but not of Foxo3-/- mice. Our results suggest that FOXO3 can be activated by metformin leading to reduced ROS/RNS level in immune cells. This may add to the beneficial clinical effects of metformin observed in large cohort studies on longevity, cardiovascular and cancer risk.

Comparative Phosphoproteomics Reveals a Role for AMPK in Hypoxia Signaling in Testes of Oriental River Prawn (Macrobrachium nipponense)

Hypoxia is one of the major stresses in aquaculture animals. Recently, we reported that hypoxia disrupts the endocrine system and inhibits testicular function of oriental river prawns (Macrobrachium nipponense), but the molecular mechanism of testes responded to hypoxia remains largely unknown. In the present study, we aimed to integrate whole phosphoproteomic profiles of hypoxia-treated testes of the oriental river prawn (Macrobrachium nipponense). We successfully isolated sperm cells and evaluated the mitochondrial morphology and function using laser confocal microscopy, flow cytometry, and biochemical analyses. Quantitative proteomics identified 117 differentially abundant phosphorylated proteins, and these proteins are mainly involved in the pathways related to cellular processes, including autophagy, apoptosis, and the FoxO signaling pathway. Protein-protein interaction analysis clustered these phosphoproteins into three groups, many of which have been suggested to impact carbohydrate metabolism, autophagy, and signal regulation in testes. Western blotting confirmed that phosphorylated proteins including AMPK, ULK1, and TP53 (of the AMPK pathway) may contribute to testicular dysfunction caused by hypoxia. Further, we investigated the potential roles of AMP-activated protein kinase (AMPK)'s in testes mitochondrial autophagy and apoptosis in M. nipponense as induced by hypoxia. Simultaneous knockdown of AMPKα in sperm cells led to a decrease in FOXO3a phosphorylation at Ser413, upregulation of caspase-3 and caspase-9 activities, and an increased apoptosis rate. These results improve our understanding of hypoxia-induced energy metabolism disorders in the testes of M. nipponense.

Enhanced viability and function of mesenchymal stromal cell spheroids is mediated via autophagy induction

Mesenchymal stromal cells (MSCs) have received attention as promising therapeutic agents for the treatment of various diseases. However, poor post-transplantation viability is a major hurdle in MSC-based therapy, despite encouraging results in many inflammatory disorders. Recently, three dimensional (3D)-cultured MSCs (MSC_3D) were shown to have higher cell survival and enhanced anti-inflammatory effects, although the underlying mechanisms have not yet been elucidated. In this study, we investigated the molecular mechanisms by which MSC_3D gain the potential for enhanced cell viability. Herein, we found that macroautophagy/autophagy was highly induced and ROS production was suppressed in MSC_3D as compared to 2D-cultured MSCs (MSC_2D). Interestingly, inhibition of autophagy induction caused decreased cell viability and increased apoptotic activity in MSC_3D. Furthermore, modulation of ROS production was closely related to the survival and apoptosis of MSC_3D. We also observed that HMOX1 (heme oxygenase 1) was significantly up-regulated in MSC_3D. In addition, gene silencing of HMOX1 caused upregulation of ROS production and suppression of the genes related to autophagy. Moreover, inhibition of HIF1A (hypoxia inducible factor 1 subunit alpha) caused suppression of HMOX1 expression in MSC_3D, indicating that the HIF1A-HMOX1 axis plays a crucial role in the modulation of ROS production and autophagy induction in MSC_3D. Finally, the critical role of autophagy induction on improved therapeutic effects of MSC_3D was further verified in dextran sulfate sodium (DSS)-induced murine colitis. Taken together, these results indicated that autophagy activation and modulation of ROS production mediated via the HIF1A-HMOX1 axis play pivotal roles in enhancing the viability of MSC_3D.List of abbreviations:3D: three dimensional; 3MA: 3 methlyadenine; AMPK: AMP-activated protein kinase; Baf A₁: bafilomycin A₁; CFSE: carboxyfluorescein succinimidyl ester; CoCl₂: cobalt chloride; CoPP: cobalt protoporphyrin; DSS: dextran sulfate sodium; ECM: extracellular matrix; FOXO3/FOXO3A: forkhead box O3; HIF1A: hypoxia inducible factor 1 subunit alpha; HMOX1/HO-1: heme oxygenase 1; HSCs: hematopoietic stem cells; IL1A/IL-1α: interleukin 1 alpha; IL1B/IL-1β: interleukin 1 beta; IL8: interleukin 8; KEAP1: kelch like ECH associated protein 1; LAMP1: lysosomal associated membrane protein 1; LAMP2: lysosomal associated membrane protein 2; MSC_2D: 2D-cultured MSCs; MSC_3D: 3D-cultured MSCs; MSCs: mesenchymal stromal cells; NFE2L2/NRF2: nuclear factor, erythroid 2 like 2; PGE2: prostaglandin E2; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; PINK1: PTEN induced kinase 1; ROS: reactive oxygen species; siRNA: small interfering RNA; SIRT1: sirtuin 1; SOD2: superoxide dismutase 2; SQSTM1/p62: sequestosome 1; TGFB/TGF-β: transforming growth factor beta.

Calcitriol alleviates ethanol-induced hepatotoxicity via AMPK/mTOR-mediated autophagy

Excessive ethanol consumption causes cellular damage, leading to fetal alcohol syndrome and alcohol liver diseases, which are frequently seen with vitamin D (VD) deficiency. A great deal of progress has been achieved in the mechanisms of ethanol-induced hepatocyte damage. However, there are limited intervention means to reduce or rescue hepatocytes damage caused by ethanol. On the basis of our preliminary limited screen process, calcitriol showed a positive effect on protecting hepatocyte viability. Therefore, the molecular basis is worth elucidating. We found that calcitriol pretreatment markedly improved the cell viability, decreased cell apoptosis and oxidative stress and alleviated the abnormal mitochondrial morphology and membrane potential of hepatocytes induced by ethanol. Notably, autophagy was significantly enhanced by calcitriol, as evident by the increasing number of autophagosomes and autolysosomes, upregulated LC3B-Ⅱ and ATG5 levels, and promotion of p62 degradation. Furthermore, calcitriol pretreatment increased the colocalization of GFP-LC3-labeled autophagosomes with mitochondria, suggesting that calcitriol effectively promoted ethanol-induced mitophagy in hepatocytes. In addition, the inhibition of autophagy attenuated the protective and preventive effect of calcitriol. Furthermore, the effect of calcitriol on autophagy was regulated by AMPK/mTOR signaling, and signaling transduction was dependent on the Vitamin D receptor (VDR). In conclusion, calcitriol ameliorates ethanol-induced hepatocyte damage by enhancing autophagy. It may offer a convenient preventive and hepatoprotective mean for people on occasional social drink.

Globular Adiponectin Inhibits Breast Cancer Cell Growth through Modulation of Inflammasome Activation: Critical Role of Sestrin2 and AMPK Signaling

Adiponectin, an adipokine predominantly derived from adipose tissue, exhibits potent antitumor properties in breast cancer cells. However, its mechanisms of action remain elusive. Inflammasomes—intracellular multimeric protein complexes—modulate cancer cell growth in a complicated manner, as well as playing a role in the innate immune system. Herein, we examined the potential role of inflammasomes in the antitumor activity of adiponectin and found that globular adiponectin (gAcrp) significantly suppressed inflammasomes activation in breast cancer cells both in vitro and in vivo conditions, as determined by decreased expression of inflammasomes components, including NOD-like receptor pyrin domain-containing protein 3 (NLRP3) and the apoptosis-associated speck-like protein containing a CARD (ASC), and inhibition of interleukin-1β and caspase-1 activation. Treatment with pharmacological inhibitors of inflammasomes caused decrease in cell viability, apoptosis induction, and G0/G1 cell cycle arrest, suggesting that inflammasomes activation is implicated in the growth of breast cancer cells. In addition, treatment with gAcrp generated essentially similar results to those of inflammasomes inhibitors, further indicating that suppression of breast cancer cell growth by gAcrp is mediated via modulation of inflammasomes. Mechanistically, gAcrp suppressed inflammasomes activation through sestrin2 (SESN2) induction, liver kinase B1 (LKB-1)-dependent AMP-activated protein kinase (AMPK) phosphorylation, and alleviation of endoplasmic reticulum (ER) stress. Taken together, these results demonstrate that gAcrp inhibits growth of breast cancer cells by suppressing inflammasomes activation, at least in part, via SESN2 induction and AMPK activation-dependent mechanisms.

Pathogenesis, Early Diagnosis, and Therapeutic Management of Alcoholic Liver Disease

Alcoholic liver disease (ALD) refers to the damages to the liver and its functions due to alcohol overconsumption. It consists of fatty liver/steatosis, alcoholic hepatitis, steatohepatitis, chronic hepatitis with liver fibrosis or cirrhosis, and hepatocellular carcinoma. However, the mechanisms behind the pathogenesis of alcoholic liver disease are extremely complicated due to the involvement of immune cells, adipose tissues, and genetic diversity. Clinically, the diagnosis of ALD is not yet well developed. Therefore, the number of patients in advanced stages has increased due to the failure of proper early detection and treatment. At present, abstinence and nutritional therapy remain the conventional therapeutic interventions for ALD. Moreover, the therapies which target the TNF receptor superfamily, hormones, antioxidant signals, and MicroRNAs are used as treatments for ALD. In particular, mesenchymal stem cells (MSCs) are gaining attention as a potential therapeutic target of ALD. Therefore, in this review, we have summarized the current understandings of the pathogenesis and diagnosis of ALD. Moreover, we also discuss the various existing treatment strategies while focusing on promising therapeutic approaches for ALD.

The Activation and Function of Autophagy in Alcoholic Liver Disease

Autophagy is an important lysosome-mediated intracellular degradation pathway required for tissue homeostasis. Dysregulation of liver autophagy is closely associated with different liver diseases including alcoholic liver disease. Studies now indicate that autophagy may be induced or suppressed depending on the amount and the duration of ethanol treatment. Autophagy induced by ethanol serves as a protective mechanism, probably by selective degradation of the damaged mitochondria (mitophagy) and excess lipid droplets (lipophagy) and in turn attenuates alcohol-induced steatosis and liver injury. However, the detailed molecular mechanism of selective targeting of mitochondria and lipid is still unclear. Autophagy may possess other functions that protect hepatocytes from ethanol. Understanding these molecular entities would be essential in order to therapeutically module autophagy for treatment of alcoholic liver disease.

Signal Transduction Mechanisms of Alcoholic Fatty Liver Disease: Emer ging Role of Lipin-1

Lipin-1, a mammalian phosphatidic acid phosphatase (PAP), is a bi-functional molecule involved in various signaling pathways via its function as a PAP enzyme in the triglyceride synthesis pathway and in the nucleus as a transcriptional co-regulator. In the liver, lipin-1 is known to play a vital role in controlling the lipid metabolism and inflammation process at multiple regulatory levels. Alcoholic fatty liver disease (AFLD) is one of the earliest forms of liver injury and approximately 8-20% of patients with simple steatosis can develop into more severe forms of liver injury, including steatohepatitis, fibrosis/ cirrhosis, and eventually hepatocellular carcinoma (HCC). The signal transduction mechanisms for alcohol-induced detrimental effects in liver involves alteration of complex and multiple signaling pathways largely governed by a central and upstream signaling system, namely, sirtuin 1 (SIRT1)-AMP activated kinase (AMPK) axis. Emerging evidence suggests a pivotal role of lipin-1 as a crucial downstream regulator of SIRT1-AMPK signaling system that is likely to be ultimately responsible for development and progression of AFLD. Several lines of evidence demonstrate that ethanol exposure significantly induces lipin-1 gene and protein expression levels in cultured hepatocytes and in the livers of rodents, induces lipin-1-PAP activity, impairs the functional activity of nuclear lipin-1, disrupts lipin-1 mRNA alternative splicing and induces lipin-1 nucleocytoplasmic shuttling. Such impairment in response to ethanol leads to derangement of hepatic lipid metabolism, and excessive production of inflammatory cytokines in the livers of the rodents and human alcoholics. This review summarizes current knowledge about the role of lipin-1 in the pathogenesis of AFLD and its potential signal transduction mechanisms.

Adiponectin homolog novel osmotin protects obesity/diabetes-induced NAFLD by upregulating AdipoRs/PPARα signaling in ob/ob and db/db transgenic mouse models

BACKGROUND

In metabolic disorders, adiponectin and adiponectin receptors (AdipoR1/R2) signaling has a key role in improving nonalcoholic fatty liver disease (NAFLD) in obesity-associated diabetes.

OBJECTIVE

To the best of our knowledge, here, we reported for the first time the underlying mechanistic therapeutic efficacy of the novel osmotin, a homolog of mammalian adiponectin, against NAFLD in leptin-deficient ob/ob and db/db mice.

METHODS

The ob/ob and db/db mice were treated with osmotin at a dose of 5 μg/g three times a week for two weeks. To co-relate the in vivo results we used the human liver carcinoma HepG2 cells, subjected to knockdown with small siRNAs of AdipoR1/R2 and PPARα genes and treated with osmotin and palmitic acid (P.A.). MTT assay, Western blotting, immunohistofluorescence assays, and plasma biochemical analyses were applied.

RESULTS

Osmotin stimulated AdipoR1/R2 and its downstream APPL1/PPAR-α/AMPK/SIRT1 pathways in ob/ob and db/db mice, and HepG2 cells exposed to P.A. Mechanistically, we confirmed that knockdown of AdipoR1/R2 and PPARα by their respective siRNAs abolished the osmotin activity in HepG2 cells exposed to P.A. Overall, the in vivo and in vitro results suggested that osmotin protected against NAFLD through activation of AdipoR1/R2 and its downstream APPL1/PPAR-α/AMPK/SIRT1 pathways as shown by the reduced body weight, blood glucose level and glycated hemoglobin, improved glucose tolerance, attenuated insulin resistance and hepatic glucogenesis, regulated serum lipid parameters, and increased fatty acid oxidation and mitochondrial functions.

CONCLUSION

Our findings strongly suggest that novel osmotin might be a potential novel therapeutic tool against obesity/diabetes-induced NAFLD and other metabolic disorders.

Adiponectin Signaling Pathways in Liver Diseases

In the liver, adiponectin regulates both glucose and lipid metabolism and exerts an insulin-sensitizing effect. The binding of adiponectin with its specific receptors induces the activation of a proper signaling cascade that becomes altered in liver pathologies. This review describes the different signaling pathways in healthy and diseased hepatocytes, also highlighting the beneficial role of adiponectin in autophagy activation and hepatic regeneration.

Delphinidin induced protective autophagy via mTOR pathway suppression and AMPK pathway activation in HER-2 positive breast cancer cells

Background

We have previously demonstrated the anticancer effect of anthocyanins. In this study, we explored the biological activities of delphinidin, the most common of the anthocyanidin monomers, that were related to autophagy in HER-2 positive breast cancer MDA-MB-453 and BT474 cells.

Methods

The effects of various doses of delphinidin on the proliferation and apoptosis of MDA-MB-453 and BT474 cells were analysed. Autophagy was identified as a critical factor that influenced chemotherapy, and the autophagic mechanism in delphinidin-treated cells was investigated. The autophagy inhibitors, 3-MA and BA1, were used to analyse the effects of autophagy inhibition.

Results

Delphinidin inhibited proliferation, promoted apoptosis, and induced autophagy in MDA-MB-453 and BT474 cells in a dose-dependent manner. The inhibition of autophagy enhanced the delphinidin-induced apoptosis and antiproliferative effect in both HER-2 positive breast cancer cells. In addition, delphinidin induced autophagy via suppression of the mTOR signalling pathway and activation of the AMPK signalling pathway in HER-2 positive breast cancer cells.

Conclusions

Collectively, the results showed that delphinidin induced apoptosis and autophagy in HER-2 positive breast cancer cells and that autophagy was induced via the mTOR and AMPK signalling pathways. The suppression of autophagy promoted the anticancer effects of delphinidin.

YJI-7 Suppresses ROS Production and Expression of Inflammatory Mediators via Modulation of p38MAPK and JNK Signaling in RAW 264.7 Macrophages

Chalcone, (2E)-1,3-Diphenylprop-2-en-1-one, and its synthetic derivatives are known to possess anti-oxidative and anti-inflammatory properties. In the present study, we prepared a novel synthetic chalcone compound, (E)-1-(4-hydroxyphenyl)-3-(2-(trifluoromethoxy)phenyl)prop-2-en-1-one name (YJI-7), and investigated its inhibitory effects on endotoxin-stimulated production of reactive oxygen species (ROS) and expression of inflammatory mediators in macrophages. We demonstrated that treatment of RAW 264.7 macrophages with YJI-7 significantly suppressed lipopolysaccharide (LPS)-stimulated ROS production. We also found that YJI-7 substantially decreased NADPH oxidase activity stimulated by LPS, indicating that YJI-7 regulates ROS production via modulation of NADPH oxidase in macrophages. Furthermore, YJI-7 strongly inhibited the expression of a number of inflammatory mediators in a gene-selective manner, suggesting that YJI-7 possesses potent anti-inflammatory properties, as well as anti-oxidative activity. In continuing experiments to investigate the mechanisms that could underlie such biological effects, we revealed that YJI-7 suppressed phosphorylation of p38MAPK and JNK stimulated by LPS, whereas no significant effect on ERK was observed. Furthermore, LPS-stimulated production of ROS, activation of NADPH oxidase and expression of inflammatory mediators were markedly suppressed by treatment with selective inhibitor of p38MAPK (SB203580) and JNK (SP600125). Taken together, these results demonstrated that YJI-7, a novel synthetic chalcone derivative, suppressed LPS-stimulated ROS production via modulation of NADPH oxidase and diminished expression of inflammatory mediators, at least in part, via down-regulation of p38MAPK and JNK signaling in macrophages.

Dihydromyricetin protects against liver ischemia/reperfusion induced apoptosis via activation of FOXO3a-mediated autophagy

Liver ischemia and reperfusion (I/R) injury is characterized by defective liver autophagy accompanied by alterations to the endogenous defense system. Dihydromyricetin (DHM) is a natural flavonoid that demonstrates a wide range of physiological functions, and has been implicated as a regulator of autophagy. This study investigates the protective effects of DHM pretreatment on liver injury caused by ischemia/reperfusion (I/R) and elucidates the potential mechanism of DHM-mediated protection. Mice were subjected to 60 minutes of ischemia followed by 5 hours of reperfusion. DHM (100 mg/kg bw/day) or the vehicle was administered daily by gavage 7 days before ischemia and immediately before reperfusion. In this study, DHM markedly decreased serum aminotransferase activity and inhibited liver I/R -stimulated apoptosis. Moreover, DHM exerted hepatoprotective effects by upregulating mRNA levels of various essential autophagy-related genes including ATG5, ATG12, BECN1, and LC3. Autophagy inhibitor chloroquine or Atg5 knockdown blocked DHM -mediated elevation in liver function. Specifically, DHM significantly increased FOXO3a expression, and enhanced FOXO3a nuclear translocation and Ser588 phosphorylation modification. Importantly, the inhibition of FOXO3a with FOXO3a-siRNA in mice decreased DHM-induced autophagy-related genes and diminished the protective effects of DHM against liver I/R injury. In summary, these findings identify DHM as a novel hepatoprotective small molecule by elevating FOXO3a expression and nuclear translocation, stimulating autophagy-related genes and suppressing liver I/R-induced apoptosis, suggesting FOXO3a may have therapeutic value in liver cell protection in liver I/R injury.

Unravelling the role of fatty acid metabolism in cancer through the FOXO3-FOXM1 axis

Obesity and cachexia represent divergent states of nutritional and metabolic imbalance but both are intimately linked to cancer. There is an extensive overlap in their signalling pathways and molecular components involved such as fatty acids (FAs), which likely play a crucial role in cancer. Forkhead box (FOX) proteins are responsible of a wide range of transcriptional programmes during normal development, and the FOXO3-FOXM1 axis is associated with cancer initiation, progression and drug resistance. Free fatty acids (FFAs), FA synthesis and β-oxidation are associated with cancer development and progression. Meanwhile, insulin and some adipokines, that are up-regulated by FAs, are also involved in cancer development and poor prognosis. In this review, we discuss the role of FA metabolism in cancer and how FA metabolism integrates with the FOXO3-FOXM1 axis. These new insights may provide leads to better cancer diagnostics as well as strategies for tackling cancer development, progression and drug resistance.

Adiponectin inhibits inflammatory cytokines production by Beclin-1 phosphorylation and B-cell lymphoma 2 mRNA destabilization: role for autophagy induction

BACKGROUND AND PURPOSE

Adiponectin potently suppresses inflammatory mediator production. Autophagy is known to play a critical role in the modulation of inflammatory responses by adiponectin. However, the underlying mechanisms are not clearly understood. Interaction between Beclin-1 and B-cell lymphoma 2 (Bcl-2) is a critical event in autophagy induction. We examined the effects of globular adiponectin (gAcrp) on the Beclin-1/Bcl-2 association and its underlying mechanisms.

EXPERIMENTAL APPROACH

The effect of gAcrp on the interaction between Beclin-1 and Bcl-2 was examined by immunoprecipitation followed by Western blotting. To elucidate the underlying mechanisms, we determined the effects of gAcrp on Beclin-1 phosphorylation and Bcl-2 mRNA stability, and investigated their role in the suppression of inflammatory mediators using pharmacological inhibitors and transient target gene knockdown.

KEY RESULTS

Globular adiponectin disrupted the association between Beclin-1 and Bcl-2 and increased Beclin-1 phosphorylation at Thr¹¹⁹ , critical residue for binding with Bcl-2, via a death-associated protein kinase-1 (DAPK1)-dependent mechanism. Moreover, gAcrp reduced Bcl-2 expression via Bcl-2 mRNA destabilization, without significantly affecting Bcl-2 promoter activity and protein degradation, which was mediated by tristetraprolin (TTP) induction. Finally, DAPK1 and TTP were shown to play key roles in gAcrp-induced autophagosome formation and suppression of LPS-stimulated TNF-α and IL-1β expression.

CONCLUSION AND IMPLICATIONS

Beclin-1 phosphorylation and Bcl-2 mRNA destabilization mediated by DAPK1 and TTP are crucial events leading to autophagy and the suppression of inflammatory cytokine production by gAcrp. These results provide novel mechanisms underlying adiponectin's modulation of inflammatory responses. DAPK and TTP are potential therapeutic targets for the management of inflammation.

Promotion of autophagosome–lysosome fusion via salvianolic acid A-mediated SIRT1 up-regulation ameliorates alcoholic liver disease

Autophagosome and lysosome fusion was restored by salvianolic acid A-mediated SIRT1 up-regulation and protected against chronic ethanol-induced liver injury.

Estrogen receptor signaling mediates leptin-induced growth of breast cancer cells via autophagy induction

Leptin, a hormone derived from adipose tissue, promotes growth of cancer cells via multiple mechanisms. Estrogen receptor signaling is also known to stimulate the growth of breast cancer cells. However, the involvement of estrogen receptor signaling in the oncogenic actions of leptin and its underlying mechanisms are not clearly understood. Herein, we investigated mechanisms for estrogen receptor signaling-mediated growth of breast cancer cells, particularly focusing on autophagy, which plays a crucial role in leptin-induced tumor growth. Inhibition of estrogen receptor signaling via gene silencing or treatment with a pharmacological inhibitor (tamoxifen) abolished leptin-induced growth of MCF-7 human breast cancer cells. Interestingly, leptin-induced autophagy activation, determined by up-regulation of autophagy-related genes and autophagosome formation, was also significantly suppressed by inhibiting estrogen receptor signaling. Moreover, inhibition of estrogen receptor markedly prevented leptin-induced activation of AMPK/FoxO3A axis, which plays a crucial role in autophagy induction. Leptin-induced cell cycle progression and Bax down-regulation were also prevented by treatment with tamoxifen. The pivotal roles of estrogen receptor signaling in leptin-induced cell cycle progression, apoptosis suppression, and autophagy induction were further confirmed in MCF-7 tumor xenograft model. Taken together, these results demonstrate that estrogen receptor signaling plays a key role in leptin-induced growth of breast cancer cells via autophagy activation.

Globular Adiponectin Inhibits Lipopolysaccharide-Primed Inflammasomes Activation in Macrophages via Autophagy Induction: The Critical Role of AMPK Signaling

The inflammasome acts as a key platform for the activation of pro-inflammatory cytokines. Adiponectin exhibits potent anti-inflammatory properties. However, the effect of adiponectin on the modulation of the inflammasome has not been explored. Herein, we show that globular adiponectin (gAcrp) suppressed lipopolysaccharide (LPS)-primed inflammasomes activation in murine peritoneal macrophages judged by prevention of interleukin-1β (IL-1β) maturation, caspase-1 activation, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) speck formation, and pyroptotic cell death. Interestingly, pretreatment with 3-methyl adenine, a pharmacological inhibitor of autophagy, abrogated the suppressive effects of gAcrp on IL-1β secretion and caspase-1 activation, indicating the crucial role of autophagy induction in gAcrp-modulation of the inflammasome activation. In addition, inhibition of 5′Adenosine monophaspahate (AMP)-activated protein kinase (AMPK) signaling abolished suppressive effect of gAcrp on inflammasomes activation. Furthermore, autophagy induction or inhibition of the inflammasome activation by gAcrp was not observed in macrophages deficient in AMPK. Taken together, these results indicate that adiponectin inhibits LPS-primed inflammasomes activation in macrophages via autophagy induction and AMPK signaling-dependent mechanisms.

FoxO1-AMPK-ULK1 Regulates Ethanol-Induced Autophagy in Muscle by Enhanced ATG14 Association with the BECN1-PIK3C3 Complex

BACKGROUND

Excessive alcohol (EtOH) consumption causes an imbalance in protein metabolism. EtOH impairs protein synthesis in C2C12 myoblasts via a FoxO1-AMPK-TSC2-mTORC1 pathway and also induces protein degradation. As the underlying regulatory signaling cascades for these processes are currently poorly defined, we tested the hypothesis that alcohol-induced autophagy is mediated via activation of the PIK3C3 complex that is regulated by FoxO1-AMPK.

METHODS

C2C12 myoblasts were incubated with EtOH for various periods of time, and autophagy pathway-related proteins were assessed by Western blotting and immunoprecipitation. Expression of targeted genes was suppressed using electroporation of specific siRNAs and chemical inhibitors.

RESULTS

Incubation of C2C12 myoblasts with 100 mM EtOH increased the autophagy markers LC3B-II and ATG7, whereas levels of SQSTM1/p62 decreased. The lysosomal inhibitor bafilomycin A1 caused a similar response, although there was no additive effect when combined with EtOH. EtOH altered ULK1 S555 and S757 phosphorylation in a time- and AMPK-dependent manner. The activation of AMPK and ULK1 was associated with increased BECN1 (S93, S14) and PIK3C3/VPS34 (S164) phosphorylation as well as increased total ATG14 and PIK3C3. These changes promoted formation of the ATG14-AMBRA1-BECN1-PIK3C3 proautophagy complex that is important in autophagosome formation. EtOH-induced changes were not associated with increased production of PtdIns3P, which may be due to enhanced PIK3C3 complex binding with 14-3-3θ. Reduction of AMPK using siRNA suppressed the stimulatory effect of EtOH on BECN1 S93, BECN1 S14, and PIK3C3 S164 phosphorylation in a time-dependent manner. Likewise, knockdown of AMPK or chemical inhibition of FoxO1 attenuated phosphorylation of ULK1 at both residues. Knockdown of ULK1 or BECN1 antagonized the effect of EtOH on LC3B-II, SQSTM1, and ATG7 protein expression.

CONCLUSIONS

EtOH-induced autophagy is mediated through changes in phosphorylation and interaction of various PIK3C3 complex components. This, in turn, is regulated either directly via FoxO1-AMPK or indirectly via the FoxO1-AMPK-ULK1 signaling cascade in a mTORC1-independent or mTORC1-dependent manner.

Dihydromyricetin modulates p62 and autophagy crosstalk with the Keap-1/Nrf2 pathway to alleviate ethanol-induced hepatic injury

Increasing evidence has demonstrated that dihydromyricetin (DMY) contains highly effective antioxidative, anti-inflammatory, anti-microbial and anti-diabetic properties. Nevertheless, the underlying hepatoprotective mechanisms of DMY have infrequently been reported thus far. In the present study, C57BL/6 mice were fed with the Lieber-DeCarli diet containing alcohol or isocaloric maltose dextrin as a control diet with or without DMY (75 and 150mg/kg/d bw) for 6 weeks. DMY significantly attenuated hepatic enzyme release, hepatic lipid peroxidation and triglyceride deposition induced by chronic alcohol exposure. In addition, DMY dramatically attenuated the alcohol-triggered elevation of the level of inflammatory cytokines and partially recovered hepatic pathological changes. Notably, DMY remarkably modified aberrant expression of CYP2E1, Keap-1 and HO-1 in the liver and simultaneously ameliorated disordered nuclear localization of NF-κB and Nrf2 to exert its hepatoprotective effects. Further mechanistic exploration suggested that DMY activated Nrf2, possibly mediated through the autophagy pathway. Analysis of the crosstalk among p62, Keap-1 and Nrf2 demonstrated that the p62 upregulation caused by DMY contributes to a positive feedback loop in Nrf2 activation. In summary, DMY likely modulates p62 and autophagy crosstalk with the Keap-1/Nrf2 pathway to alleviate liver steatosis and the inflammatory response in the pathological progression of ALD.

Role of p62 in the suppression of inflammatory cytokine production by adiponectin in macrophages: Involvement of autophagy and p21/Nrf2 axis

Adiponectin possesses potent anti-inflammatory properties. p62, an adaptor protein composed of multi-functional domain, is known to play a role in controlling inflammatory responses. In the present study, we examined the role of p62 in suppressing inflammatory cytokines produced by globular adiponectin (gAcrp) and the potential underlying mechanisms in macrophages. We demonstrated that gAcrp significantly increased p62 expression. Knockdown of p62 abrogated the suppressive effects of gAcrp on LPS-stimulated TNF-α and IL-1β expression and TRAF6/p38 MAPK pathway, indicating that p62 signaling is critical for suppressing inflammatory cytokines production by gAcrp. We next examined the role of p62 in gAcrp-induced autophagy activation, because autophagy has been shown to play a pivotal role in suppressing TNF-α. Herein, we observed that gene silencing of p62 prevented gAcrp-induced increases in autophagy-related genes and autophagosome formation. In addition, we found that Nrf2 knockdown prevented gAcrp-induced p62 expression, and p21 knockdown prevented Nrf2 induction, suggesting the role of p21/Nrf2 axis in gAcrp-induced p62 expression. Taken together, these findings imply that p62 signaling plays a crucial role in suppressing inflammatory cytokine production by globular adiponectin in macrophages, at least in part, through autophagy induction. Furthermore, the p21/Nrf2 signaling cascade contributes to p62 induction by globular adiponectin.

Time-Dependent Changes in Apoptosis Upon Autophagy Inhibition in Astrocytes Exposed to Oxygen and Glucose Deprivation

Recent studies have implicated the role of autophagy in brain ischemia pathophysiology. However, it remains unclear whether autophagy activation is protective or detrimental to astrocytes undergoing ischemic stress. This study evaluated the influence of ischemia-induced autophagy on cell death and the course of intrinsic and extrinsic apoptosis in primary cultures of rat cortical astrocytes exposed to combined oxygen-glucose deprivation (OGD). The role of autophagy was assessed by pharmacological inhibition with 3-methyladenine (3-MA). Cell viability was evaluated by measuring LDH release and through the use of the alamarBlue Assay. Apoptosis and necrosis were determined by fluorescence microscopy after Hoechst 33,342 and propidium iodide staining, respectively. The levels of apoptosis-related proteins were analyzed by immunoblotting. The downregulation of autophagy during OGD resulted in decreased cell viability and time-dependent changes in levels of apoptosis and necrosis. After short-term OGD (1, 4 h), cells treated with 3-MA showed higher level of cleaved caspase 3 compared with control cells. This result was consistent with an evaluation of apoptotic cell number by fluorescence microscopy. However, after prolonged exposure to OGD (8, 24 h), the number of apoptotic astrocytes (microscopically evaluated) did not differ or was even lower (as marked by caspase 3) in the presence of the autophagy inhibitor in comparison to the control. A higher level of necrosis was observed in 3-MA-treated cells compared to non-treated cells after 24 h OGD. The downregulation of autophagy caused time-dependent changes in both extrinsic (cleaved caspase 8, TNFα) and intrinsic (cleaved caspase 9) apoptotic pathways. Our results strongly indicate that the activation of autophagy in astrocytes undergoing ischemic stress is an adaptive mechanism, which allows for longer cell survival by delaying the initiation of apoptosis and necrosis.

Grifola frondosa Glycoprotein GFG-3a Arrests S phase, Alters Proteome, and Induces Apoptosis in Human Gastric Cancer Cells

GFG-3a is a novel glycoprotein previously purified from the fermented mycelia of Grifola frondosa with novel sugar compositions and protein sequencing. The present study aims to investigate its effects on the cell cycle, differential proteins expression, and apoptosis of human gastric cancer SGC-7901 cells. Our findings revealed that GFG-3a induced the cell apoptosis and arrested cell cycle at S phase. GFG-3a treatment resulted in the differential expression of 21 proteins in SGC-7901 cells by upregulating 10 proteins including RBBP4 associated with cell cycle arrest and downregulating 11 proteins including RUVBL1, NPM, HSP90AB1, and GRP78 involved in apoptosis and stress response. qRT-PCR and Western blot analysis also suggested that GFG-3a could increase the expressions of Caspase-8/-3, p53, Bax, and Bad while decrease the expressions of Bcl2, Bcl-xl, PI3K, and Akt1. These results indicated that the stress response, p53-dependent mitochondrial-mediated, Caspase-8/-3-dependent, and PI3k/Akt pathways were involved in the GFG-3a-induced apoptosis process in SGC-7901 cells. These findings might provide a basis to prevent or treat human gastric cancer with GFG-3a and understand the tumor-inhibitory molecular mechanisms of mushroom glycoproteins.

Corosolic acid protects hepatocytes against ethanol-induced damage by modulating mitogen-activated protein kinases and activating autophagy

The reactive oxygen species(ROS)/mitogen-activated protein kinase (MAPK) destroyed autophagy and the reactive oxygen species/mitogen-activated protein kinase (MAPK) pathway are considered closely related to ethanol-induced hepatocellular injury. Previous work indicated that corosolic acid, the natural extracts of leaves of the banaba tree, Lagerstroemia speciosa L., could protect the liver against ethanol-induced damage, but the underlying mechanism is unclear. In the study we found that corosolic acid significantly inhibited ethanol-induced apoptosis, increased level of tumor necrosis factor-α(TNF-α) and reactive oxygen species accumulation in vitro. Corosolic acid inhibited ethanol-activated p38 and c-Jun N-terminal kinase MAPK signaling in BRL-3A and HepG2 cells as well as in experimental rats. Corosolic acid restored the ethanol-suppressed expression of autophagy-related genes, including beclin-1 and the ratio of microtubule-associated protein light chain 3II/I (LC3II/I) via AMP-activated protein kinase (AMPK) activation both in vitro and in vivo. In experimental rats, corosolic acid ameliorated the detrimental histopathological findings. Corosolic acid may protect the liver against ethanol-induced injury by modulation of MAPK signaling and autophagy activation. These findings suggested that corosolic acid might be a promising agent in treatment of alcoholic liver diseases.

p53 signaling is involved in leptin-induced growth of hepatic and breast cancer cells

Leptin, an adipokine predominantly produced from adipose tissue, is well known to induce tumor growth. However, underlying molecular mechanisms are not established yet. While p53 has long been well recognized as a potent tumor suppressor gene, accumulating evidence has also indicated its potential role in growth and survival of cancer cells depending on experimental environments. In the present study, we examined if p53 signaling is implicated in leptin-induced growth of cancer cells. Herein, we demonstrated that leptin treatment significantly increased p53 protein expression in both hepatic (HepG2) and breast (MCF-7) cancer cells without significant effect on mRNA expression. Enhanced p53 expression by leptin was mediated via modulation of ubiquitination, in particular ubiquitin specific protease 2 (USP2)-dependent manner. Furthermore, gene silencing of p53 by small interfering RNA (siRNA) suppressed leptin-induced growth of hepatic and breast cancer cells, indicating the role of p53 signaling in tumor growth by leptin. In addition, we also showed that knockdown of p53 restored suppression of caspase-3 activity by leptin through modulating Bax expression and prevented leptin-induced cell cycle progression, implying the involvement of p53 signaling in the regulation of both apoptosis and cell cycle progression in cancer cells treated with leptin. Taken together, the results in the present study demonstrated the potential role of p53 signaling in leptin-induced tumor growth.

Autophagy in ethanol-exposed liver disease

Ethanol metabolism in hepatocytes causes the generation of reactive oxygen species, endoplasmic reticulum stress and alterations in mitochondrial energy and REDOX metabolism. In ethanol-exposed liver disease, autophagy not only acts as a cleanser to remove damaged organelles and cytosolic components, but also selectively clears specific targets such as lipid droplets and damaged mitochondria. Moreover, ethanol appears to play a role in protecting hepatocytes from apoptosis at certain concentrations. This article describes the evidence, function and potential mechanism of autophagy in ethanol-exposed liver disease and the controversy surrounding the effects of ethanol on autophagy.

Modulation of Cell Death and Survival by Adipokines in the Liver

Adipokines, hormones predominantly produced from adipose tissue, have been shown to impart dynamic functions in the liver. Emerging evidence has shown that adipokines are also involved in modulating liver cell survival and/or death. Among the various adipokines, adiponectin and leptin directly regulate proliferation of hepatocytes, Kupffer cells, and hepatic stellate cells. Moreover, these adipokines control apoptosis and cell cycle of hepatic cancer cells in a complex manner. Adiponectin possesses both pro- and anti-proliferative properties, whereas leptin appears to play roles as a pro-survival hormone. Recent studies have revealed that regulation of cell death and proliferation is one of the critical factors regulating liver physiology by adipokines. In this review, we summarize the effects of adipokines on apoptosis and survival of liver cells and also demonstrate their implications in regulating various liver functions and decipher the underlying molecular mechanisms.

Macrophage migration inhibitory factor induces autophagy to resist hypoxia/serum deprivation-induced apoptosis via the AMP-activated protein kinase/mammalian target of rapamycin signaling pathway

Macrophage migration inhibitory factor (MIF) is an anti‑apoptotic agent in various cell types and protects the heart from stress‑induced injury by modulating autophagy. Autophagy, a conserved pathway for bulk degradation of intracellular proteins and organelles, helps to preserve and recycle energy and nutrients for cells to survive during starvation. The present study hypothesized that MIF protects bone marrow‑derived mesenchymal stem cells (MSCs) from apoptosis by modulating autophagy via the AMP‑activated protein kinase/mammalian target of rapamycin (AMPK/mTOR) signaling pathway. MSCs were obtained from rat bone marrow and cultured. Apoptosis was induced by hypoxia/serum deprivation for 24 h and was assessed using flow cytometry. MIF protected MSCs from apoptosis by modulating autophagy via the AMPK/mTOR signaling pathway resulting in increased expression of autophagy‑associated proteins (including LC3BI/LC3BII, Beclin‑1 and autophagy protein 5), and by increased phosphorylation of AMPK and decreased phosphorylation of mTOR. The MIF anti‑apoptotic effects were blocked by autophagy inhibitor, 3‑methyladenine or AMPK inhibitor, Compound C. These results indicate that MIF exerts a permissive role in protecting MSCs from apoptosis by regulation of autophagy via the AMPK/mTOR signaling pathway.

Autophagy induction by leptin contributes to suppression of apoptosis in cancer cells and xenograft model: involvement of p53/FoxO3A axis

Leptin, a hormone mainly produced from adipose tissue, has been shown to induce proliferation of cancer cells. However, the molecular mechanisms underlying leptin-induced tumor progression have not been clearly elucidated. In the present study, we investigated the role of autophagy in leptin-induced cancer cell proliferation using human hepatoma (HepG2) and breast cancer cells (MCF-7), and tumor growth in a xenograft model. Herein, we showed that leptin treatment caused autophagy induction as assessed by increase in expression of autophagy-related genes, including beclin-1, Atg5 and LC3 II, further induction of autophagosome formation and autophagic flux. Interestingly, inhibition of autophagic process by treatment with inhibitors and LC3B gene silencing blocked leptin-induced increase in cell number and suppression of apoptosis, indicating a crucial role of autophagy in leptin-induced tumor progression. Moreover, gene silencing of p53 or FoxO3A prevented leptin-induced LC3 II protein expression, suggesting an involvement of p53/FoxO3A axis in leptin-induced autophagy activation. Leptin administration also accelerated tumor growth in BALB/c nude mice, which was found to be autophagy dependent. Taken together, our results demonstrate that leptin-induced tumor growth is mediated by autophagy induction and autophagic process would be a promising target to regulate development of cancer caused by leptin production.

Quercetin Attenuates Chronic Ethanol-Induced Hepatic Mitochondrial Damage through Enhanced Mitophagy

Emerging evidence suggested mitophagy activation mitigates ethanol-induced liver injury. However, the effect of ethanol on mitophagy is inconsistent. Importantly, the understanding of mitophagy status after chronic ethanol consumption is limited. This study evaluated the effect of quercetin, a naturally-occurring flavonoid, on chronic ethanol-induced mitochondrial damage focused on mitophagy. An ethanol regime to mice for 15 weeks (accounting for 30% of total calories) led to significant mitochondrial damage as evidenced by changes of the mitochondrial ultrastructure, loss of mitochondrial membrane potential and remodeling of membrane lipid composition, which was greatly attenuated by quercetin (100 mg/kg.bw). Moreover, quercetin blocked chronic ethanol-induced mitophagy suppression as denoted by mitophagosomes-lysosome fusion and mitophagy-related regulator elements, including LC3II, Parkin, p62 and voltage-dependent anion channel 1 (VDAC1), paralleling with increased FoxO3a nuclear translocation. AMP-activated protein kinase (AMPK) and extracellular signal regulated kinase 2 (ERK2), instead of AKT and Sirtuin 1, were involved in quercetin-mediated mitophagy activation. Quercetin alleviated ethanol-elicited mitochondrial damage through enhancing mitophagy, highlighting a promising preventive strategy for alcoholic liver disease.