A hepatocyte growth factor receptor (Met)-insulin receptor hybrid governs hepatic glucose metabolism. Nat Med. 2011;17:1577-1584. [PMID: 22081023 PMCID: PMC3233634 DOI: 10.1038/nm.2531]

Gender effect of glucose, insulin/glucagon ratio, lipids, and nitrogen-metabolites on serum HGF and EGF levels in patients with diabetes type 2

Hepatocyte growth factor (HGF) exhibits potent growth-inducing properties across various tissues, while epidermal growth factor (EGF) acts as a molecular integration point for diverse stimuli. HGF plays a crucial role in hepatic metabolism, tissue repair, and offers protective effects on epithelial and non-epithelial organs, in addition to its involvement in reducing apoptosis and inflammation, underscoring its anti-inflammatory capabilities. The HGF-Met system is instrumental in hepatic metabolism and enhancing insulin sensitivity in animal diabetes models. Similarly, the EGF and its receptor tyrosine kinase family (EGFR) are critical in regulating cell growth, proliferation, migration, and differentiation in both healthy and diseased states, with EGF also contributing to insulin sensitivity. In this observational study, we aimed to identify correlations between serum levels of HGF and EGF, insulin, glucagon, glucose, and primary serum lipids in patients with type 2 diabetes mellitus (DM), taking into account the impact of gender. We noted differences in the management of glucose, insulin, and glucagon between healthy men and women, potentially due to the distinct influences of sexual hormones on the development of type 2 DM. Additionally, metabolites such as glucose, albumin, direct bilirubin, nitrites, and ammonia might influence serum levels of growth factors and hormones. In summary, our results highlight the regulatory role of insulin and glucagon in serum glucose and lipids, along with variations in HGF and EGF levels, which are affected by gender. This link is especially significant in DM, where impaired cell proliferation or repair mechanisms lead to metabolic changes. The gender-based differences in growth factors point to their involvement in the pathophysiology of the disease.

Basal MET phosphorylation is an indicator of hepatocyte dysregulation in liver disease

Chronic liver diseases are worldwide on the rise. Due to the rapidly increasing incidence, in particular in Western countries, metabolic dysfunction-associated steatotic liver disease (MASLD) is gaining importance as the disease can develop into hepatocellular carcinoma. Lipid accumulation in hepatocytes has been identified as the characteristic structural change in MASLD development, but molecular mechanisms responsible for disease progression remained unresolved. Here, we uncover in primary hepatocytes from a preclinical model fed with a Western diet (WD) an increased basal MET phosphorylation and a strong downregulation of the PI3K-AKT pathway. Dynamic pathway modeling of hepatocyte growth factor (HGF) signal transduction combined with global proteomics identifies that an elevated basal MET phosphorylation rate is the main driver of altered signaling leading to increased proliferation of WD-hepatocytes. Model-adaptation to patient-derived hepatocytes reveal patient-specific variability in basal MET phosphorylation, which correlates with patient outcome after liver surgery. Thus, dysregulated basal MET phosphorylation could be an indicator for the health status of the liver and thereby inform on the risk of a patient to suffer from liver failure after surgery.

Potential mechanisms underlying the effect of hepatocyte growth factor on liver injury in short bowel syndrome model rats

PURPOSE

The purpose of this study was to investigate the autophagy associated with apoptosis in hepatic damage in the short bowel syndrome rat model.

METHODS

SD rats underwent jugular vein catheterization for continuous total parenteral nutrition (TPN) and 90% small bowel resection. Animals were divided into two groups: TPN plus SBS (Control group) or TPN plus SBS plus intravenous administration of HGF (HGF group). On day 7, the rats were harvested, and hepatocellular injury was evaluated.

RESULTS

In an SBS rat model, hepatic steatosis and lobular inflammation were histologically suppressed in the HGF group (p < 0.01). The expression of tumor necrosis factor-α in the HGF group tend to be higher than that in the control group (p = 0.13). The gene expression of transforming Growth Factor-β in the HGF group was suppressed compared to the control group (p < 0.01). HGF treatment may have an antiapoptotic effect via the intrinsic pathway by caspase 9. Protein expressions of Rubicon (p = 0.03) and p62 (p < 0.01) in the HGF group were found to have increased compared to those in the control group.

CONCLUSION

The inhibitory effect of HGF on hepatic steatosis remains unclear, and further studies focusing on the mechanisms of fat accumulation are needed.

Deoxysphingolipids: Atypical Skeletal Muscle Lipids Related to Insulin Resistance in Humans That Decrease Insulin Sensitivity In Vitro

Sphingolipids are thought to promote skeletal muscle insulin resistance. Deoxysphingolipids (dSLs) are atypical sphingolipids that are increased in the plasma of individuals with type 2 diabetes and cause β-cell dysfunction in vitro. However, their role in human skeletal muscle is unknown. We found that dSL species are significantly elevated in muscle of individuals with obesity and type 2 diabetes compared with athletes and lean individuals and are inversely related to insulin sensitivity. Furthermore, we observed a significant reduction in muscle dSL content in individuals with obesity who completed a combined weight loss and exercise intervention. Increased dSL content in primary human myotubes caused a decrease in insulin sensitivity associated with increased inflammation, decreased AMPK phosphorylation, and altered insulin signaling. Our findings reveal a central role for dSL in human muscle insulin resistance and suggest dSLs as therapeutic targets for the treatment and prevention of type 2 diabetes.

ARTICLE HIGHLIGHTS

Deoxysphingolipids (dSLs) are atypical sphingolipids elevated in the plasma of individuals with type 2 diabetes, and their role in muscle insulin resistance has not been investigated. We evaluated dSL in vivo in skeletal muscle from cross-sectional and longitudinal insulin-sensitizing intervention studies and in vitro in myotubes manipulated to synthesize higher dSLs. dSLs were increased in the muscle of people with insulin resistance, inversely correlated to insulin sensitivity, and significantly decreased after an insulin-sensitizing intervention; increased intracellular dSL concentrations cause myotubes to become more insulin resistant. Reduction of muscle dSL levels is a potential novel therapeutic target to prevent/treat skeletal muscle insulin resistance.

HGFAC is a ChREBP-regulated hepatokine that enhances glucose and lipid homeostasis

Carbohydrate response element-binding protein (ChREBP) is a carbohydrate-sensing transcription factor that regulates both adaptive and maladaptive genomic responses in coordination of systemic fuel homeostasis. Genetic variants in the ChREBP locus associate with diverse metabolic traits in humans, including circulating lipids. To identify novel ChREBP-regulated hepatokines that contribute to its systemic metabolic effects, we integrated ChREBP ChIP-Seq analysis in mouse liver with human genetic and genomic data for lipid traits and identified hepatocyte growth factor activator (HGFAC) as a promising ChREBP-regulated candidate in mice and humans. HGFAC is a protease that activates the pleiotropic hormone hepatocyte growth factor. We demonstrate that HGFAC-KO mice had phenotypes concordant with putative loss-of-function variants in human HGFAC. Moreover, in gain- and loss-of-function genetic mouse models, we demonstrate that HGFAC enhanced lipid and glucose homeostasis, which may be mediated in part through actions to activate hepatic PPARγ activity. Together, our studies show that ChREBP mediated an adaptive response to overnutrition via activation of HGFAC in the liver to preserve glucose and lipid homeostasis.

β2-adrenergic receptor promotes liver regeneration partially through crosstalk with c-met

The β₂-adrenergic receptor (β₂AR) is a G protein-coupled receptor (GPCR) that mediates the majority of cellular responses to external stimuli. Aberrant expression of β₂AR results in various pathophysiological disorders, including tumorigenesis, but little is known about its role in liver regeneration. This study aims to investigate the impact and the underlying mechanism of β₂AR in liver regeneration. Here, we found that β₂AR was upregulated during liver regeneration induced by 70% PH. Deletion of β₂AR in mice resulted in 62% mortality 2 days post-PH, decreased proliferative marker expression and impaired liver function throughout regeneration. Moreover, AAV8-mediated overexpression of β₂AR in hepatocytes accelerated the regeneration process and increased target gene expression. Mechanistically, β₂AR recruited G-protein-coupled receptor kinase 2 (GRK2) to the membrane and then formed a complex with c-met to transactivate c-met signaling, which triggered downstream extracellular regulated protein kinase (ERK) signaling activation and nuclear translocation. Inhibition of c-met with SU11274 or ERK with U0126 decreased β₂AR overexpression-induced hepatocyte proliferation. Our findings revealed that β₂AR might act as a critical mediator regulating liver regeneration by crosstalk with c-met and activation of ERK signaling.

Comparative Transcriptomics of Gonads Reveals the Molecular Mechanisms Underlying Gonadal Development in Giant Freshwater Prawns (Macrobrachium rosenbergii)

The giant freshwater prawn, Macrobrachium rosenbergii, is a prawn that has economic significance throughout the world. It exhibits sex-related growth dimorphism, whereby the males grow significantly more rapidly than the females. Therefore, a study on the molecular regulatory mechanism, which underlies the sexual differentiation of M. rosenbergii, is of both scientific and commercial importance. However, a scarcity of genomic and transcriptomic resources severely limits our knowledge of the sexual differentiation mechanisms in M. rosenbergii. Here, transcriptome sequencing of several gonadic samples of males and females in M. rosenbergii was performed to investigate the molecular basis underlying gonadal development. Our results showed that 2149 unigenes presented as differentially expressed genes (DEGs) in the ovaries of females compared to the testes of males, which contained 484 down-regulated and 1665 up-regulated genes. Enrichment analysis of DEGs revealed many of these genes to be related to sexual differentiation and gonadal development. From our transcriptome analyses, and as confirmed by quantitative real-time PCR, male-related genes (Mrr, MRPINK, IR, IAGBP, TESK1, and dsx) in the testes were significantly up-regulated, and female-related genes (ERR, Sxl3, cyclinB, Dmrt99B, PPP2A, and ADCY9) in the ovaries were also significantly up-regulated. This indicates the potential role these genes play in the gonadal development of M. rosenbergii. Furthermore, multiple signal transduction pathways relating to gonadal maturation and spermatogenesis, including MAPK, were identified herein. Our data also supports previous ideas that IAG and IAGBP-IR signaling schemes could help in the regulation of testis’ development in M. rosenbergii and the ERR gene could regulate ovarian development by affecting the expression of cyclinB, PPP2A, and ADCY9. The data from this study provides incredibly usefully genomic resources for future research on the sexual differentiation and practical aquaculture of M. rosenbergii.

SERPINA3C ameliorates adipose tissue inflammation through the Cathepsin G/Integrin/AKT pathway

Objective

Due to the increasing prevalence of obesity and insulin resistance, there is an urgent need for better treatment of obesity and its related metabolic disorders. This study aimed to elucidate the role of SERPINA3C, an adipocyte secreted protein, in obesity and related metabolic disorders.

Methods

Male wild type (WT) and knockout (KO) mice were fed with high-fat diet (HFD) for 16 weeks, adiposity, insulin resistance, and inflammation were assessed. AAV-mediated overexpression of SERPINA3C was injected locally in inguinal white adipose tissue (iWAT) to examine the effect of SERPINA3C. In vitro analyses were conducted in 3T3-L1 adipocytes to explore the molecular pathways underlying the function of SERPINA3C.

Results

Functional exploration of the SERPINA3C knockout mice revealed that SERPINA3C deficiency led to an impaired metabolic phenotype (more severe obesity, lower metabolic rates, worse glucose intolerance and insulin insensitivity), which was associated with anabatic inflammation and apoptosis of white adipose tissues. Consistent with these results, overexpression of SERPINA3C in inguinal adipose tissue protected mice against diet-induced obesity and metabolic disorders with less inflammation and apoptosis in adipose tissue. Mechanistically, SERPINA3C inhibited Cathepsin G activity, acting as a serine protease inhibitor, which blocked Cathepsin G-mediated turnover of α5/β1 Integrin protein. Then, the preserved integrity (increase) of α5/β1 Integrin signaling activated AKT to decrease JNK phosphorylation, thereby inhibiting inflammation and promoting insulin sensitivity in adipocytes.

Conclusions/interpretation

These findings demonstrate a previously unknown SERPINA3C/Cathepsin G/Integrin/AKT pathway in regulating adipose tissue inflammation, and suggest the therapeutic potential of targeting SERPINA3C/Cathepsin G axis in adipose tissue for the treatment of obesity and metabolic diseases.

•

SERPINA3C deletion aggravated HFD-induced obesity, insulin resistance and inflammation in mice.

•

Overexpression of SERPINA3C in iWAT alleviated HFD-induced obesity, insulin resistance and inflammation.

•

SERPINA3C relieved adipose inflammation by inhibiting Cathepsin G-mediated turnover of Integrin α5/β1 to activate AKT.

•

The SERPINA3C/Cathepsin G axis in adipose might be a potential therapeutic target for type 2 diabetes and obesity.

Enhanced Wild-Type MET Receptor Levels in Mouse Hepatocytes Attenuates Insulin-Mediated Signaling

Compelling evidence points to the MET receptor tyrosine kinase as a key player during liver development and regeneration. Recently, a role of MET in the pathophysiology of insulin resistance and obesity is emerging. Herein, we aimed to determine whether MET regulates hepatic insulin sensitivity. To achieve this, mice in which the expression of wild-type MET in hepatocytes is slightly enhanced above endogenous levels (Alb-R26^Met mice) were analyzed to document glucose homeostasis, energy balance, and insulin signaling in hepatocytes. We found that Alb-R26^Met mice exhibited higher body weight and food intake when compared to R26^stopMet control mice. Metabolic analyses revealed that Alb-R26^Met mice presented age-related glucose and pyruvate intolerance in comparison to R26^stopMet controls. Additionally, in Alb-R26^Met mice, high MET levels decreased insulin-induced insulin receptor (IR) and AKT phosphorylation compared to control mice. These results were corroborated in vitro by analyzing IR and AKT phosphorylation in primary mouse hepatocytes from Alb-R26^Met and R26^stopMet mice upon insulin stimulation. Moreover, co-immunoprecipitation assays revealed MET-IR interaction under both basal and insulin stimulation conditions; this effect was enhanced in Alb-R26^Met hepatocytes. Altogether, our results indicate that enhanced MET levels alter hepatic glucose homeostasis, which can be an early event for subsequent liver pathologies.

Liver Fibrosis-From Mechanisms of Injury to Modulation of Disease

The Transregional Collaborative Research Center "Organ Fibrosis: From Mechanisms of Injury to Modulation of Disease" (referred to as SFB/TRR57) was funded for 13 years (2009-2021) by the German Research Council (DFG). This consortium was hosted by the Medical Schools of the RWTH Aachen University and Bonn University in Germany. The SFB/TRR57 implemented combined basic and clinical research to achieve detailed knowledge in three selected key questions: (i) What are the relevant mechanisms and signal pathways required for initiating organ fibrosis? (ii) Which immunological mechanisms and molecules contribute to organ fibrosis? and (iii) How can organ fibrosis be modulated, e.g., by interventional strategies including imaging and pharmacological approaches? In this review we will summarize the liver-related key findings of this consortium gained within the last 12 years on these three aspects of liver fibrogenesis. We will highlight the role of cell death and cell cycle pathways as well as nutritional and iron-related mechanisms for liver fibrosis initiation. Moreover, we will define and characterize the major immune cell compartments relevant for liver fibrogenesis, and finally point to potential signaling pathways and pharmacological targets that turned out to be suitable to develop novel approaches for improved therapy and diagnosis of liver fibrosis. In summary, this review will provide a comprehensive overview about the knowledge on liver fibrogenesis and its potential therapy gained by the SFB/TRR57 consortium within the last decade. The kidney-related research results obtained by the same consortium are highlighted in an article published back-to-back in Frontiers in Medicine.

Liver regeneration biology: Implications for liver tumour therapies

The liver has remarkable regenerative potential, with the capacity to regenerate after 75% hepatectomy in humans and up to 90% hepatectomy in some rodent models, enabling it to meet the challenge of diverse injury types, including physical trauma, infection, inflammatory processes, direct toxicity, and immunological insults. Current understanding of liver regeneration is based largely on animal research, historically in large animals, and more recently in rodents and zebrafish, which provide powerful genetic manipulation experimental tools. Whilst immensely valuable, these models have limitations in extrapolation to the human situation. In vitro models have evolved from 2-dimensional culture to complex 3 dimensional organoids, but also have shortcomings in replicating the complex hepatic micro-anatomical and physiological milieu. The process of liver regeneration is only partially understood and characterized by layers of complexity. Liver regeneration is triggered and controlled by a multitude of mitogens acting in autocrine, paracrine, and endocrine ways, with much redundancy and cross-talk between biochemical pathways. The regenerative response is variable, involving both hypertrophy and true proliferative hyperplasia, which is itself variable, including both cellular phenotypic fidelity and cellular trans-differentiation, according to the type of injury. Complex interactions occur between parenchymal and non-parenchymal cells, and regeneration is affected by the status of the liver parenchyma, with differences between healthy and diseased liver. Finally, the process of termination of liver regeneration is even less well understood than its triggers. The complexity of liver regeneration biology combined with limited understanding has restricted specific clinical interventions to enhance liver regeneration. Moreover, manipulating the fundamental biochemical pathways involved would require cautious assessment, for fear of unintended consequences. Nevertheless, current knowledge provides guiding principles for strategies to optimise liver regeneration potential.

A Novel Humanized Model of NASH and Its Treatment With META4, A Potent Agonist of MET

BACKGROUND & AIMS

Nonalcoholic fatty liver disease is a frequent cause of hepatic dysfunction and is now a global epidemic. This ailment can progress to an advanced form called nonalcoholic steatohepatitis (NASH) and end-stage liver disease. Currently, the molecular basis of NASH pathogenesis is poorly understood, and no effective therapies exist to treat NASH. These shortcomings are due to the paucity of experimental NASH models directly relevant to humans.

METHODS

We used chimeric mice with humanized liver to investigate nonalcoholic fatty liver disease in a relevant model. We carried out histologic, biochemical, and molecular approaches including RNA-Seq. For comparison, we used side-by-side human NASH samples.

RESULTS

Herein, we describe a "humanized" model of NASH using transplantation of human hepatocytes into fumarylacetoacetate hydrolase-deficient mice. Once fed a high-fat diet, these mice develop NAFLD faithfully, recapitulating human NASH at the histologic, cellular, biochemical, and molecular levels. Our RNA-Seq analyses uncovered that a variety of important signaling pathways that govern liver homeostasis are profoundly deregulated in both humanized and human NASH livers. Notably, we made the novel discovery that hepatocyte growth factor (HGF) function is compromised in human and humanized NASH at several levels including a significant increase in the expression of the HGF antagonists known as NK1/NK2 and marked decrease in HGF activator. Based on these observations, we generated a potent, human-specific, and stable agonist of human MET that we have named META4 (Metaphor) and used it in the humanized NASH model to restore HGF function.

CONCLUSIONS

Our studies revealed that the humanized NASH model recapitulates human NASH and uncovered that HGF-MET function is impaired in this disease. We show that restoring HGF-MET function by META4 therapy ameliorates NASH and reinstates normal liver function in the humanized NASH model. Our results show that the HGF-MET signaling pathway is a dominant regulator of hepatic homeostasis.

HGF can reduce accumulation of inflammation and regulate glucose homeostasis in T2D mice

Hepatocyte growth factor (HGF) has been studied as a protective factor for the survival of islet β cells and regulatory glucose transport and metabolism in many studies. The addition of exogenous HGF to cells or mice is the most common way to study HGF, but the persistence and stability of the administered HGF are unclear. In this experiment, wild-type C57BL6 (WT) mice and HGF-overexpressing transgenic (HGF-Tg) mice were divided into a normal diet (ND) group and an HFD group. The HGF protein level in the liver, kidney, spleen, pancreas, and VAT of HGF-Tg-ND mice was upregulated compared to that of WT-ND mice, and it was also upregulated in HGF-Tg-HFD mice compared to that in WT-HFD mice. In the ND group, though the HGF-Tg-ND mice showed higher fasted blood glucose levels and larger integrated density (IOD) of glucagon-positive cells than WT-ND mice, we found that HGF-Tg-ND mice can still maintain normal glucose tolerance based on an intraperitoneal glucose tolerance test (IPGTT) and an intraperitoneal insulin tolerance test (IPITT). In the HFD group, the HGF-Tg-HFD mice showed insulin sensitivity in IPGTT and IPITT and had larger areas and higher IOD values of islet β cells and smaller areas and IOD values of islet α cells than the WT-HFD mice. HGF-Tg-HFD mice had lower level of serum insulin than WT-HFD mice. The HGF-Tg-HFD mice showed inhibited accumulation of CD4+ T cells, CD8+ T cells, Ly6G+ neutrophils, and F4/80+ macrophages in the blood and tissues and protected liver and kidney functions. Oil Red O-stained liver sections revealed that WT-HFD mice had larger areas and higher IOD values of Oil Red O-positive cells than HGF-Tg-HFD mice, and WT-HFD mice had higher score of NASH. PAS-stained kidney sections found WT-HFD has higher mesangial area/glomerular area × 100% than HGF-Tg-HFD mice. Comparative analyses demonstrated that HGF reduces the proportions of inflammatory cells in the blood and tissues, and protects liver and kidney tissues by regulating glucose homeostasis of type 2 diabetic mice.

Breaking the cycle: Targeting of NDRG1 to inhibit bi-directional oncogenic cross-talk between pancreatic cancer and stroma

Pancreatic cancer (PaCa) is characterized by dense stroma that hinders treatment efficacy, with pancreatic stellate cells (PSCs) being a major contributor to this stromal barrier and PaCa progression. Activated PSCs release hepatocyte growth factor (HGF) and insulin-like growth factor (IGF-1) that induce PaCa proliferation, metastasis and resistance to chemotherapy. We demonstrate for the first time that the metastasis suppressor, N-myc downstream regulated gene 1 (NDRG1), is a potent inhibitor of the PaCa-PSC cross-talk, leading to inhibition of HGF and IGF-1 signaling. NDRG1 also potently reduced the key driver of PaCa metastasis, namely GLI1, leading to reduced PSC-mediated cell migration. The novel clinically trialed anticancer agent, di-2-pyridylketone 4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC), which upregulates NDRG1, potently de-sensitized PaCa cells to ligands secreted by activated PSCs. DpC and NDRG1 also inhibited the PaCa-mediated activation of PSCs via inhibition of sonic hedgehog (SHH) signaling. In vivo, DpC markedly reduced PaCa tumor growth and metastasis more avidly than the standard chemotherapy for this disease, gemcitabine. Uniquely, DpC was selectively cytotoxic against PaCa cells, while "re-programming" PSCs to an inactive state, decreasing collagen deposition and desmoplasia. Thus, targeting NDRG1 can effectively break the oncogenic cycle of PaCa-PSC bi-directional cross-talk to overcome PaCa desmoplasia and improve therapeutic outcomes.

miR-93-5p promotes insulin resistance to regulate type 2 diabetes progression in HepG2 cells by targeting HGF

Insulin resistance is a common feature of type 2 diabetes mellitus (T2DM). However, the mechanisms underlying insulin resistance are not completely understood. The present study aimed to investigate the effect of microRNA (miR)-93-5p on insulin resistance in T2DM cells. Human hepatocellular carcinoma (HCC; HepG2) cells were cultured in medium with high glucose content (30 mM glucose) to establish an in vitro insulin-resistant cell model (IR group). Glucose consumption and glycogen synthesis assays were performed to assess glucose consumption and glycogen synthesis, respectively. By performing immunoprecipitation assays, the abundance of the Met-insulin receptor complex was detected in HepG2 cells. miR-93-5p and hepatocyte growth factor (HGF) mRNA expression levels were measured via reverse transcription-quantitative PCR, and HGF protein expression levels were measured via western blotting. A dual-luciferase reporter assay was conducted to investigate the interaction between miR-93-5p and HGF. Cell Counting Kit-8, BrdU and caspase-3 activity assays were performed to evaluate cell viability, proliferation and apoptosis, respectively, in insulin-resistant HepG2 cells following transfection with small interfering RNA-HGF, HGF overexpression vector, miR-93-5p mimic or miR-93-5p inhibitor. The results demonstrated that miR-93-5p expression was significantly increased and HGF expression was significantly decreased in HCC tissues isolated from patients with or without T2DM compared with adjacent healthy tissues isolated from patients without T2DM. Compared with the IR group, miR-93-5p overexpression significantly increased cell proliferation, glucose consumption and glycogen synthesis, but significantly inhibited apoptosis in insulin-resistant HepG2 cells. By contrast, compared with the IR group, HGF overexpression significantly inhibited cell proliferation, glucose consumption and glycogen synthesis, but significantly enhanced cell apoptosis in insulin-resistant HepG2 cells. Following co-transfection with HGF overexpression vector and miR-93-5p mimic, miR-93-5p mimic-mediated induction of HepG2 cell proliferation, glucose consumption and glycogen synthesis in insulin-resistant HepG2 cells was inhibited. Collectively, the results of the present study indicated that miR-93-5p enhanced insulin resistance to regulate T2DM progression in HepG2 cells by targeting HGF.

MiR-22-3p suppresses cell growth via MET/STAT3 signaling in lung cancer

MiR-22-3p has been reported to be down-regulated in several cancers, but its expression pattern and roles in lung cancer is unclear. Given the crucial role of microRNAs in cancer progression, we examined the expression and function of miR-22-3p in lung adenocarcinoma. MiR-22-3p expression in lung cancer tissues and cell lines was measured by qRT-PCR. Cell proliferation was measured by WST-1 and colony formation assays were used to reveal the role of miR-22-3p in lung cancer in vitro. MiR-22-3p was notably down-regulated in lung cancer tissues as compared to normal lung tissues, but it was not associated with the clinical characteristics of tumor stage, differentiation and patient's smoking status. Colony formation ability and cell proliferation were suppressed by miR-22-3p mimics in lung cancer cell lines. Mechanistically, miR-22-3p mimics could reduce MET and STAT3 protein expression and induce apoptosis as measured by PARP protein. We conclude that miR-22-3p may play a tumor suppressor role via inhibiting MET-STAT3 signaling and have potential to be a therapeutic target and biomarker in lung adenocarcinoma.

Design, synthesis and biological evaluation of 7H-pyrrolo[2,3-d]pyrimidine derivatives containing 1,8-naphthyridine-4-one fragment

In this study, a series of pyrrolo [2,3-d]pyrimidine derivatives containing 1,8-naphthyridine-4-one fragment were synthesized and their biological activity were tested. Most of the target compounds displayed moderate to excellent activity against one or more cancer cell lines and low activity against human normal cell LO2 in vitro. The most promising compound 51, of which the IC₅₀ values were 0.66 μM, 0.38 μM and 0.44 μM against cell lines A549, Hela and MCF-7, shown more remarkable activity and better apoptosis effect than the positive control Cabozantinib. The structure-activity relationships (SARs) indicated that double-EWGs (such as R₃ = 2-Cl-4-CF₃) on the terminal phenyl rings was a key factor in improving the biological activity. In addition, the further research on compound 51 mainly included c-Met kinase activity and selectivity, concentration dependence, and molecular docking.

Liver regeneration: biological and pathological mechanisms and implications

The liver is the only solid organ that uses regenerative mechanisms to ensure that the liver-to-bodyweight ratio is always at 100% of what is required for body homeostasis. Other solid organs (such as the lungs, kidneys and pancreas) adjust to tissue loss but do not return to 100% of normal. The current state of knowledge of the regenerative pathways that underlie this 'hepatostat' will be presented in this Review. Liver regeneration from acute injury is always beneficial and has been extensively studied. Experimental models that involve partial hepatectomy or chemical injury have revealed extracellular and intracellular signalling pathways that are used to return the liver to equivalent size and weight to those prior to injury. On the other hand, chronic loss of hepatocytes, which can occur in chronic liver disease of any aetiology, often has adverse consequences, including fibrosis, cirrhosis and liver neoplasia. The regenerative activities of hepatocytes and cholangiocytes are typically characterized by phenotypic fidelity. However, when regeneration of one of the two cell types fails, hepatocytes and cholangiocytes function as facultative stem cells and transdifferentiate into each other to restore normal liver structure. Liver recolonization models have demonstrated that hepatocytes have an unlimited regenerative capacity. However, in normal liver, cell turnover is very slow. All zones of the resting liver lobules have been equally implicated in the maintenance of hepatocyte and cholangiocyte populations in normal liver.

HGF/c-Met Signalling in the Tumor Microenvironment

Recently, it has become clearer that tumor plasticity increases the chance that cancer cells could acquire new mechanisms to escape immune surveillance, become resistant to conventional drugs, and spread to distant sites.Effectively, tumor plasticity drives adaptive response of cancer cells to hypoxia and nutrient deprivation leading to stimulation of neoangionesis or tumor escape. Therefore, tumor plasticity is believed to be a great contributor in recurrence and metastatic dissemination of cancer cells. Importantly, it could be an Achilles' heel of cancer if we could identify molecular mechanisms dictating this phenotype.The reactivation of stem-like signalling pathways is considered a great determinant of tumor plasticity; in addition, a key role has been also attributed to tumor microenvironment (TME). Indeed, it has been proved that cancer cells interact with different cells in the surrounding extracellular matrix (ECM). Interestingly, well-established communication represents a potential allied in maintenance of a plastic phenotype in cancer cells supporting tumor growth and spread. An important signalling pathway mediating cancer cell-TME crosstalk is represented by the HGF/c-Met signalling.Here, we review the role of the HGF/c-Met signalling in tumor-stroma crosstalk focusing on novel findings underlying its role in tumor plasticity, immune escape, and development of adaptive mechanisms.

Animal Models: A Useful Tool to Unveil Metabolic Changes in Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma (HCC) represents an important health problem. At the moment, systemic therapies offered only modest clinical benefits. Thus, HCC represents a cancer extremely difficult to treat, and therapeutic breakthroughs are urgently needed. Metabolic reprogramming of neoplastic cells has been recognized as one of the core hallmarks of cancer. Experimental animal models represent an important tool that allows to investigate metabolic changes underlying HCC development and progression. In the present review, we characterize available rodent models of hepatocarcinogenesis. Moreover, we discuss the possibility that pharmacological targeting of Warburg metabolism may represent an additional tool to improve already available therapeutic approaches for HCC.

Abstract

Hepatocellular carcinoma (HCC) is one the most frequent and lethal human cancers. At present, no effective treatment for advanced HCC exist; therefore, the overall prognosis for HCC patients remains dismal. In recent years, a better knowledge of the signaling pathways involved in the regulation of HCC development and progression, has led to the identification of novel potential targets for therapeutic strategies. However, the obtained benefits from current therapeutic options are disappointing. Altered cancer metabolism has become a topic of renewed interest in the last decades, and it has been included among the core hallmarks of cancer. In the light of growing evidence for metabolic reprogramming in cancer, a wide number of experimental animal models have been exploited to study metabolic changes characterizing HCC development and progression and to further expand our knowledge of this tumor. In the present review, we discuss several rodent models of hepatocarcinogenesis, that contributed to elucidate the metabolic profile of HCC and the implications of these changes in modulating the aggressiveness of neoplastic cells. We also highlight the apparently contrasting results stemming from different animal models. Finally, we analyze whether these observations could be exploited to improve current therapeutic strategies for HCC.

Hepatocyte growth factor/MET and CD44 in colorectal cancer: partners in tumorigenesis and therapy resistance

Intestinal epithelial self-renewal is a tightly controlled process, which is critically dependent on WNT signalling. Aberrant activation of the WNT pathway in intestinal stem cells (ISCs) results in constitutive transcription of target genes, which collectively drive malignant transformation in colorectal cancer (CRC). However, the contribution of individual genes to intestinal homeostasis and tumorigenesis often is incompletely defined. Here, we discuss converging evidence indicating that the receptor tyrosine kinase (RTK) MET and its ligand hepatocyte growth factor (HGF) play a major role in the intestinal damage response, as well as in intestinal tumorigenesis, by controlling the proliferation, survival, motility, and stemness of normal and neoplastic intestinal epithelial cells. These activities of MET are promoted by specific CD44 isoforms expressed by ISCs. The accrued data indicate that MET and the EGFR have overlapping roles in the biology of intestinal epithelium and that metastatic CRCs can exploit this redundancy to escape from EGFR-targeted treatments, co-opting HGF/MET/CD44v signalling. Hence, targeting both pathways may be required for effective treatment of (a subset of) CRCs. The RTK identity of MET, the distinctive 'plasminogen-like' structure and activation mode of its ligand HGF, and the specific collaboration of MET with CD44, provide several unique targeting options, which merit further exploration.

Regulation of Energy Metabolism by Receptor Tyrosine Kinase Ligands

Metabolic diseases, such as diabetes, obesity, and fatty liver disease, have now reached epidemic proportions. Receptor tyrosine kinases (RTKs) are a family of cell surface receptors responding to growth factors, hormones, and cytokines to mediate a diverse set of fundamental cellular and metabolic signaling pathways. These ligands signal by endocrine, paracrine, or autocrine means in peripheral organs and in the central nervous system to control cellular and tissue-specific metabolic processes. Interestingly, the expression of many RTKs and their ligands are controlled by changes in metabolic demand, for example, during starvation, feeding, or obesity. In addition, studies of RTKs and their ligands in regulating energy homeostasis have revealed unexpected diversity in the mechanisms of action and their specific metabolic functions. Our current understanding of the molecular, biochemical and genetic control of energy homeostasis by the endocrine RTK ligands insulin, FGF21 and FGF19 are now relatively well understood. In addition to these classical endocrine signals, non-endocrine ligands can govern local energy regulation, and the intriguing crosstalk between the RTK family and the TGFβ receptor family demonstrates a signaling network that diversifies metabolic process between tissues. Thus, there is a need to increase our molecular and mechanistic understanding of signal diversification of RTK actions in metabolic disease. Here we review the known and emerging molecular mechanisms of RTK signaling that regulate systemic glucose and lipid metabolism, as well as highlighting unexpected roles of non-classical RTK ligands that crosstalk with other receptor pathways.

Evaluation of associations between genetically predicted circulating protein biomarkers and breast cancer risk

A small number of circulating proteins have been reported to be associated with breast cancer risk, with inconsistent results. Herein, we attempted to identify novel protein biomarkers for breast cancer via the integration of genomics and proteomics data. In the Breast Cancer Association Consortium (BCAC), with 122,977 cases and 105,974 controls of European descendants, we evaluated the associations of the genetically predicted concentrations of >1,400 circulating proteins with breast cancer risk. We used data from a large-scale protein quantitative trait loci (pQTL) analysis as our study instrument. Summary statistics for these pQTL variants related to breast cancer risk were obtained from the BCAC and used to estimate odds ratios (OR) for each protein using the inverse-variance weighted method. We identified 56 proteins significantly associated with breast cancer risk by instrumental analysis (false discovery rate <0.05). Of these, the concentrations of 32 were influenced by variants close to a breast cancer susceptibility locus (ABO, 9q34.2). Many of these proteins, such as insulin receptor, insulin-like growth factor receptor 1 and other membrane receptors (OR: 0.82-1.18, p values: 6.96 × 10-4 -3.28 × 10-8 ), are linked to insulin resistance and estrogen receptor signaling pathways. Proteins identified at other loci include those involved in biological processes such as alcohol and lipid metabolism, proteolysis, apoptosis, immune regulation and cell motility and proliferation. Consistent associations were observed for 22 proteins in the UK Biobank data (p < 0.05). The study identifies potential novel biomarkers for breast cancer, but further investigation is needed to replicate our findings.

Pharmacologic Inhibition of Epidermal Growth Factor Receptor Suppresses Nonalcoholic Fatty Liver Disease in a Murine Fast-Food Diet Model

Epidermal growth factor receptor (EGFR) is a critical regulator of hepatocyte proliferation and liver regeneration. Our recent work indicated that EGFR can also regulate lipid metabolism during liver regeneration after partial hepatectomy. Based on these findings, we investigated the role of EGFR in a mouse model of nonalcoholic fatty liver disease (NAFLD) using a pharmacological inhibition strategy. C57BL6/J mice were fed a chow diet or a fast-food diet (FFD) with or without EGFR inhibitor (canertinib) for 2 months. EGFR inhibition completely prevented development of steatosis and liver injury in this model. In order to study if EGFR inhibition can reverse NAFLD progression, mice were fed the FFD for 5 months, with or without canertinib treatment for the last 5 weeks of the study. EGFR inhibition remarkably decreased steatosis, liver injury, and fibrosis and improved glucose tolerance. Microarray analysis revealed that ~40% of genes altered by the FFD were differentially expressed after EGFR inhibition and, thus, are potentially regulated by EGFR. Several genes and enzymes related to lipid metabolism (particularly fatty acid synthesis and lipolysis), which were disrupted by the FFD, were found to be modulated by EGFR. Several crucial transcription factors that play a central role in regulating these lipid metabolism genes during NAFLD, including peroxisome proliferator-activated receptor gamma (PPARγ), sterol regulatory element-binding transcription factor 1 (SREBF1), carbohydrate-responsive element-binding protein, and hepatocyte nuclear factor 4 alpha, were also found to be modulated by EGFR. In fact, chromatin immunoprecipitation analysis revealed that PPARγ binding to several crucial lipid metabolism genes (fatty acid synthase, stearoyl-coenzyme A desaturase 1, and perilipin 2) was drastically reduced by EGFR inhibition. Further upstream, EGFR inhibition suppressed AKT signaling, which is known to control these transcription factors, including PPARγ and SREBF1, in NAFLD models. Lastly, the effect of EGFR in FFD-induced fatty-liver phenotype was not shared by receptor tyrosine kinase MET, investigated using MET knockout mice. Conclusion: Our study revealed a role of EGFR in NAFLD and the potential of EGFR inhibition as a treatment strategy for NAFLD.

Insulin/IGF signaling and discoidin domain receptors: An emerging functional connection

The insulin/insulin-like growth factor system (IIGFs) plays a fundamental role in the regulation of prenatal and postnatal growth, metabolism and homeostasis. As a consequence, dysregulation of this axis is associated with growth disturbance, type 2 diabetes, chronic inflammation and tumor progression. A functional crosstalk between IIGFs and discoidin domain receptors (DDRs) has been recently discovered. DDRs are non-integrin collagen receptors that canonically undergo slow and long-lasting autophosphorylation after binding to fibrillar collagen. While both DDR1 and DDR2 functionally interact with IIGFs, the crosstalk with DDR1 is so far better characterized. Notably, the IIGFs-DDR1 crosstalk presents a feed-forward mechanism, which does not require collagen binding, thus identifying novel non-canonical action of DDR1. Further studies are needed to fully explore the role of this IIGFs-DDRs functional loop as potential target in the treatment of inflammatory and neoplastic disorders.

Amelioration of Endoplasmic Reticulum Stress by Mesenchymal Stem Cells via Hepatocyte Growth Factor/c-Met Signaling in Obesity-Associated Kidney Injury

Recent advances in the understanding of lipid metabolism suggest a critical role of endoplasmic reticulum (ER) stress in obesity‐induced kidney injury. Hepatocyte growth factor (HGF) is a pleiotropic cytokine frequently featured in stem cell therapy with distinct renotropic benefits. This study aims to define the potential link between human induced pluripotent stem cell‐derived mesenchymal stem cells (iPS‐MSCs)/bone marrow‐derived MSCs (BM‐MSCs) and ER stress in lipotoxic kidney injury induced by palmitic acid (PA) in renal tubular cells and by high‐fat diet (HFD) in mice. iPS‐MSCs or BM‐MSCs alleviated ER stress (by preventing induction of Bip, chop, and unfolded protein response), inflammation (Il6, Cxcl1, and Cxcl2), and apoptosis (Bax/Bcl2 and terminal deoxynucleotidyl transferase‐mediated dUTP‐biotin nick end labeling‐positive cells) in renal cortex of animals exposed to HFD thus mitigating histologic damage and albuminuria, via activating HGF/c‐Met paracrine signaling that resulted in enhanced HGF secretion in the glomerular compartment and c‐Met expression in the tubules. Coculture experiments identified glomerular endothelial cells (GECs) to be the exclusive source of glomerular HGF when incubated with either iPS‐MSCs or BM‐MSCs in the presence of PA. Furthermore, both GEC‐derived HGF and exogenous recombinant HGF attenuated PA‐induced ER stress in cultured tubular cells, and this effect was abrogated by a neutralizing anti‐HGF antibody. Taken together, this study is the first to demonstrate that MSCs ameliorate lipotoxic kidney injury via a novel microenvironment‐dependent paracrine HGF/c‐Met signaling mechanism to suppress ER stress and its downstream pro‐inflammatory and pro‐apoptotic consequences. stem cells translational medicine2019;8:898&910

A Noncanonical Role for Plasminogen Activator Inhibitor Type 1 in Obesity-Induced Diabetes

Obesity is a major risk factor for type 2 diabetes because of chronic hepatic inflammation and resultant insulin resistance. Hepatocyte growth factor (HGF) is responsible for resetting hepatic homeostasis after injury following activation by urokinase-type plasminogen activator (u-PA; encoded by the PLAU gene). Plasminogen activator inhibitor type-1 (PAI-1; encoded by the SERPINE1 gene), a u-PA inhibitor and antifibrinolytic agent, is often elevated in obesity and is linked to cardiovascular events. We hypothesized that, in addition to its role in preventing fibrinolysis, elevated PAI-1 inhibits HGF's activation by u-PA and the resultant anti-inflammatory and hepatoprotective properties. Wild-type and PAI-1 knockout (KO) mice on a high-fat diet both became significantly heavier than lean controls; however, the obese KO mice demonstrated improved glucose metabolism compared with wild-type mice. Obese KO mice also exhibited an increase in conversion of latent single-chain HGF to active two-chain HGF, coinciding with an increase in the phosphorylation of the HGF receptor (HGFR or MET, encoded by the MET gene), as well as dampened inflammation. These results strongly suggest that, in addition to its other functions, PAI-mediated inhibition of HGF activation prohibits the resolution of inflammation in the context of obesity-induced type 2 diabetes.

Hepatocyte growth factor alleviates hepatic insulin resistance and lipid accumulation in high-fat diet-fed mice

AIMS/INTRODUCTION

Type 2 diabetes mellitus is frequently accompanied by fatty liver disease. Lipid accumulation within the liver is considered as one of the risk factors for insulin resistance. Hepatocyte growth factor (HGF) is used to treat liver dysfunction; however, the effect and mechanism of HGF on hepatic lipid metabolism are still not fully understood.

MATERIALS AND METHODS

Male C57BL/6 mice were induced with a high-fat diet for 12 weeks, followed by a 4-week treatment of HGF or vehicle saline. The levels of fasting blood glucose, fasting insulin and homeostatic model assessment of insulin resistance were calculated for insulin sensitivity. Biochemical plasma parameters were also measured to assess the effect of HGF on lipid accumulation. Additionally, genes in the lipid metabolism pathway were evaluated in palmitic acid-treated HepG2 cells and high-fat diet mice.

RESULTS

HGF treatment significantly decreased the levels of fasting blood glucose, hepatic triglyceride and cholesterol contents. Additionally, HGF-regulated expression levels of sterol regulatory element-binding protein-1c/fatty acid synthase, peroxidase proliferator-activated receptor-α, and upstream nuclear receptors, such as farnesoid X receptor and small heterodimer partner. Furthermore, c-Met inhibitor could partially reverse the effects of HGF.

CONCLUSIONS

HGF treatment can ameliorate hepatic insulin resistance and steatosis through regulation of lipid metabolism. These effects might occur through farnesoid X receptor-small heterodimer partner axis-dependent transcriptional activity.

Blocking FSH inhibits hepatic cholesterol biosynthesis and reduces serum cholesterol

Menopause is associated with dyslipidemia and an increased risk of cardio-cerebrovascular disease. The classic view assumes that the underlying mechanism of dyslipidemia is attributed to an insufficiency of estrogen. In addition to a decrease in estrogen, circulating follicle-stimulating hormone (FSH) levels become elevated at menopause. In this study, we find that blocking FSH reduces serum cholesterol via inhibiting hepatic cholesterol biosynthesis. First, epidemiological results show that the serum FSH levels are positively correlated with the serum total cholesterol levels, even after adjustment by considering the effects of serum estrogen. In addition, the prevalence of hypercholesterolemia is significantly higher in peri-menopausal women than that in pre-menopausal women. Furthermore, we generated a mouse model of FSH elevation by intraperitoneally injecting exogenous FSH into ovariectomized (OVX) mice, in which a normal level of estrogen (E2) was maintained by exogenous supplementation. Consistently, the results indicate that FSH, independent of estrogen, increases the serum cholesterol level in this mouse model. Moreover, blocking FSH signaling by anti-FSHβ antibody or ablating the FSH receptor (FSHR) gene could effectively prevent hypercholesterolemia induced by FSH injection or high-cholesterol diet feeding. Mechanistically, FSH, via binding to hepatic FSHRs, activates the Gi2α/β-arrestin-2/Akt pathway and subsequently inhibits the binding of FoxO1 with the SREBP-2 promoter, thus preventing FoxO1 from repressing SREBP-2 gene transcription. This effect, in turn, results in the upregulation of SREBP-2, which drives HMGCR nascent transcription and de novo cholesterol biosynthesis, leading to the increase of cholesterol accumulation. This study uncovers that blocking FSH signaling might be a new strategy for treating hypercholesterolemia during menopause, particularly for women in peri-menopause characterized by FSH elevation only.

The Emerging Role of Insulin Receptor Isoforms in Thyroid Cancer: Clinical Implications and New Perspectives

Thyroid cancer (TC) is the most common endocrine tumor. Although the majority of TCs show good prognoses, a minor proportion are aggressive and refractory to conventional therapies. So far, the molecular mechanisms underlying TC pathogenesis are incompletely understood. Evidence suggests that TC cells and their precursors are responsive to insulin and insulin-like growth factors (IGFs), and often overexpress receptors for insulin (IR) and IGF-1 (IGF-1R). IR exists in two isoforms, namely IR-A and IR-B. The first binds insulin and IGF-2, unlike IR-B, which only binds insulin. IR-A is preferentially expressed in prenatal life and contributes to development through IGF-2 action. Aggressive TC overexpresses IR-A, IGF-2, and IGF-1R. The over-activation of IR-A/IGF-2 loop in TC is associated with stem-like features and refractoriness to some targeted therapies. Importantly, both IR isoforms crosstalk with IGF-1R, giving rise to the formation of hybrids receptors (HR-A or HR-B). Other interactions have been demonstrated with other molecules such as the non-integrin collagen receptor, discoidin domain receptor 1 (DDR1), and the receptor for the hepatocyte growth factor (HGF), Met. These functional networks provide mechanisms for IR signaling diversification, which may also exert a role in TC stem cell biology, thereby contributing to TC initiation and progression. This review focuses on the molecular mechanisms by which deregulated IR isoforms and their crosstalk with other molecules and signaling pathways in TC cells and their precursors may contribute to thyroid carcinogenesis, progression, and resistance to conventional treatments. We also highlight how targeting these alterations starting from TC progenitors cells may represent new therapeutic strategies to improve the clinical management of advanced TCs.

Interleukin-4 Boosts Insulin-Induced Energy Deposits by Enhancing Glucose Uptake and Lipogenesis in Hepatocytes

Type 2 diabetes mellitus (T2DM), with dysregulated hepatic gluconeogenesis as the major cause of fasting hyperglycemia, is closely associated with chronic inflammation. We previously demonstrated interleukin-4 (IL-4) improves insulin sensitivity and glucose tolerance while reducing lipid deposits. The present study examined the in vitro effects of IL-4 on insulin signaling molecules, glucose uptake, and lipid metabolism in hepatocytes, as well as in vivo effects on hepatic adiposity, for elucidating the roles of IL-4 in hepatic energy metabolism. Potential interaction between IL-4 and insulin in regulating hepatic metabolism was also investigated. Our results showed that IL-4 enhanced Akt and GSK-3α/β phosphorylations, which in turn promoted glycogen synthesis. IL-4 not only potentiated basal glucose uptake by upregulating glucose transporter 2 expression but also promoted insulin-induced glucose uptake. Additionally, IL-4 increased triglyceride contents through facilitating free fatty acid uptake and expression/activity of lipogenic enzymes. The major effects of IL-4 on the liver were to promote energy storage by boosting insulin-stimulated glucose uptake and lipid synthesis. This study provides evidence to implicate the novel roles of IL-4 in mediating hepatic glucose and lipid metabolism, interactions between immune responses and metabolic homeostasis, and the involvement of IL-4 in metabolic abnormalities.

Updates on the hepatocyte growth factor/c-Met axis in hepatocellular carcinoma and its therapeutic implications

Hepatocellular carcinoma (HCC) is the fifth most common cancer and is the second leading cause of cancer death. Since the diagnosis of HCC is difficult, in many cases patients with HCC are diagnosed advanced stage of development. Hepatocyte growth factor (HGF)/c-mesenchymal-epithelial transition receptor (c-Met) axis is a key signaling pathway in HCC, either via canonical or non-canonical pathways. Available treatments against HCC based upon HGF/c-Met inhibition can increase patient lifespan, but do not reach the expected therapeutic benefits. In HCC, c-Met monomers can bind other receptor monomers, activating several noncanonical signaling pathways, leading to increased cell proliferation, invasion, motility, and drug resistance. All of these processes are enhanced by the tumor microenvironment, with stromal cells contributing to boost tumor progression through oxidative stress, angiogenesis, lymphangiogenesis, inflammation, and fibrosis. Novel treatments against HCC are being explored to modulate other targets such as microRNAs, methyltransferases, and acetyltransferases, which are all involved in the regulation of gene expression in cancer. This review compiles basic knowledge regarding signaling pathways in HCC, and compounds already used or showing potential to be used in clinical trials.

Targeting the vascular and perivascular niches as a regenerative therapy for lung and liver fibrosis

The regenerative capacity of lung and liver is sometimes impaired by chronic or overwhelming injury. Orthotopic transplantation of parenchymal stem cells to damaged organs might reinstate their self-repair ability. However, parenchymal cell engraftment is frequently hampered by the microenvironment in diseased recipient organs. We show that targeting both the vascular niche and perivascular fibroblasts establishes "hospitable soil" to foster the incorporation of "seed," in this case, the engraftment of parenchymal cells in injured organs. Specifically, ectopic induction of endothelial cell (EC)-expressed paracrine/angiocrine hepatocyte growth factor (HGF) and inhibition of perivascular NOX4 [NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase 4] synergistically enabled reconstitution of mouse and human parenchymal cells in damaged organs. Reciprocally, genetic knockout of Hgf in mouse ECs (Hgf^iΔEC/iΔEC) aberrantly up-regulated perivascular NOX4 during liver and lung regeneration. Dysregulated HGF and NOX4 pathways subverted the function of vascular and perivascular cells from an epithelially inductive niche to a microenvironment that inhibited parenchymal reconstitution. Perivascular NOX4 induction in Hgf^iΔEC/iΔEC mice recapitulated the phenotype of human and mouse liver and lung fibrosis. Consequently, EC-directed HGF and NOX4 inhibitor GKT137831 stimulated regenerative integration of mouse and human parenchymal cells in chronically injured lung and liver. Our data suggest that targeting dysfunctional perivascular and vascular cells in diseased organs can bypass fibrosis and enable reparative cell engraftment to reinstate lung and liver regeneration.

Insulin receptor sensitization restores neocortical excitation/inhibition balance in a mouse model of autism

Background

Met receptor tyrosine kinase regulates neurogenesis, differentiation, migration, connectivity, and synaptic plasticity. The human Met gene has been identified as a prominent risk factor for autism spectrum disorder (ASD). Met gene-altered mice serve as useful models for mechanistic studies of ASD. Inactivation of Met in excitatory cortical neurons in mice (Emx1^cre/Met^flox mice) yields a phenotype in which significantly decreased GABA_A receptor-mediated inhibition shifts the excitation/inhibition (E/I) balance toward excitation in the somatosensory cortex. Further, unlike that seen in wild-type mice, insulin does not increase inhibition in the mutant cortex, suggesting that one of the consequences of kinase inactive Met gene could be desensitization of insulin receptors. To test this hypothesis, we investigated the effects of insulin receptor sensitizer, pioglitazone, on inhibition in the somatosensory thalamocortical circuitry.

Methods

We used whole-cell patch clamp electrophysiology and analyzed excitatory and inhibitory responses of cortical layer IV excitatory cells following stimulation of their thalamic input in thalamocortical pathway intact brain slices. We applied insulin alone and insulin + a thiazolidinedione, pioglitazone (PIO), to test the effects of sensitizing insulin receptors on inhibitory responses mediated by GABA_A receptors in the somatosensory cortex of Emx1^cre/Met^flox mice.

Results

In WT brain slices, application of insulin together with PIO did not enhance the effect of insulin alone. In contrast, PIO application induced a much larger inhibition than that of insulin alone in Met-defective cortex. Thus, insulin resistance of GABA_A receptor-mediated response in Met mutant mice may result from desensitized insulin receptors.

Conclusions

Sporadic clinical studies reported improved behavioral symptoms in children with autism following PIO treatment. We show that PIO can aid in normalization of the E/I balance in the primary somatosensory cortex, a potential physiological mechanism underlying the positive effects of PIO treatment.

The Role of Hepatocyte Growth Factor (HGF) in Insulin Resistance and Diabetes

In obesity, insulin resistance (IR) and diabetes, there are proteins and hormones that may lead to the discovery of promising biomarkers and treatments for these metabolic disorders. For example, these molecules may impair the insulin signaling pathway or provide protection against IR. Thus, identifying proteins that are upregulated in IR states is relevant to the diagnosis and treatment of the associated disorders. It is becoming clear that hepatocyte growth factor (HGF) is an important component of the pathophysiology of IR, with increased levels in most common IR conditions, including obesity. HGF has a role in the metabolic flux of glucose in different insulin sensitive cell types; plays a key role in β-cell homeostasis; and is capable of modulating the inflammatory response. In this review, we discuss how, and to what extent HGF contributes to IR and diabetes pathophysiology, as well as its role in cancer which is more prevalent in obesity and diabetes. Based on the current literature and knowledge, it is clear that HGF plays a central role in these metabolic disorders. Thus, HGF levels could be employed as a biomarker for disease status/progression, and HGF/c-Met signaling pathway modulators could effectively regulate IR and treat diabetes.

Molecular spectrum of secretome regulates the relative hepatogenic potential of mesenchymal stem cells from bone marrow and dental tissue

Liver regeneration is a spontaneous process that occurs after liver injury, but acute liver failure is a complex and fatal disease which is difficult to treat. Cell-based therapies are promising alternative therapeutic approach for liver failure and different cell sources have been tested in this regard. We investigated the comparative hepatogenic potential of human bone marrow stem cells (BMSC) with stem cells derived from human dental pulp (DPSC), apical papilla (SCAP) and follicle (DFSC) during this study. Hepatogenic potential of stem cells was assessed by functional assays at both genetic and protein level. We observed higher expression of most of the hepatic markers post differentiation in DPSCs compared to other cell types. LC-MS/MS analysis of stem cell secretome revealed the presence of different proteins related to hepatogenic lineage like growth arrest specific protein 6, oncostatin M, hepatocyte growth factor receptor etc. Interactome and Reactome pathway analysis revealed the interaction of DPSC/SCAP secretome proteins and these proteins were found to be associated with various pathways involved in lipid transport and metabolism. To the best of our knowledge, this is the first study regarding detailed investigation of hepatogenic potential of BMSCs v/s DMSCs (DPSC, SCAP & DFSC) along-with secretome characterization.

Insulin Receptor Isoforms in Physiology and Disease: An Updated View

The insulin receptor (IR) gene undergoes differential splicing that generates two IR isoforms, IR-A and IR-B. The physiological roles of IR isoforms are incompletely understood and appear to be determined by their different binding affinities for insulin-like growth factors (IGFs), particularly for IGF-2. Predominant roles of IR-A in prenatal growth and development and of IR-B in metabolic regulation are well established. However, emerging evidence indicates that the differential expression of IR isoforms may also help explain the diversification of insulin and IGF signaling and actions in various organs and tissues by involving not only different ligand-binding affinities but also different membrane partitioning and trafficking and possibly different abilities to interact with a variety of molecular partners. Of note, dysregulation of the IR-A/IR-B ratio is associated with insulin resistance, aging, and increased proliferative activity of normal and neoplastic tissues and appears to sustain detrimental effects. This review discusses novel information that has generated remarkable progress in our understanding of the physiology of IR isoforms and their role in disease. We also focus on novel IR ligands and modulators that should now be considered as an important strategy for better and safer treatment of diabetes and cancer and possibly other IR-related diseases.

IGF system targeted therapy: Therapeutic opportunities for ovarian cancer

The insulin-like growth factor (IGF) system comprises multiple growth factor receptors, including insulin-like growth factor 1 receptor (IGF-1R), insulin receptor (IR) -A and -B. These receptors are activated upon binding to their respective growth factor ligands, IGF-I, IGF-II and insulin, and play an important role in development, maintenance, progression, survival and chemotherapeutic response of ovarian cancer. In many pre-clinical studies anti-IGF-1R/IR targeted strategies proved effective in reducing growth of ovarian cancer models. In addition, anti-IGF-1R targeted strategies potentiated the efficacy of platinum based chemotherapy. Despite the vast amount of encouraging and promising pre-clinical data, anti-IGF-1R/IR targeted strategies lacked efficacy in the clinic. The question is whether targeting the IGF-1R/IR signaling pathway still holds therapeutic potential. In this review we address the complexity of the IGF-1R/IR signaling pathway, including receptor heterodimerization within and outside the IGF system and downstream signaling. Further, we discuss the implications of this complexity on current targeted strategies and indicate therapeutic opportunities for successful targeting of the IGF-1R/IR signaling pathway in ovarian cancer. Multiple-targeted approaches circumventing bidirectional receptor tyrosine kinase (RTK) compensation and prevention of system rewiring are expected to have more therapeutic potential.

Deletion of Macrophage Mineralocorticoid Receptor Protects Hepatic Steatosis and Insulin Resistance Through ERα/HGF/Met Pathway

Although the importance of macrophages in nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM) has been recognized, how macrophages affect hepatocytes remains elusive. Mineralocorticoid receptor (MR) has been implicated to play important roles in NAFLD and T2DM. However, cellular and molecular mechanisms are largely unknown. We report that myeloid MR knockout (MRKO) improves glucose intolerance, insulin resistance, and hepatic steatosis in obese mice. Estrogen signaling is sufficient and necessary for such improvements. Hepatic gene and protein expression suggests that MRKO reduces hepatic lipogenesis and lipid storage. In the presence of estrogen, MRKO in macrophages decreases lipid accumulation and increases insulin sensitivity of hepatocytes through hepatocyte growth factor (HGF)/Met signaling. MR directly regulates estrogen receptor 1 (Esr1 [encoding ERα]) in macrophages. Knockdown of hepatic Met eliminates the beneficial effects of MRKO in female obese mice. These findings identify a novel MR/ERα/HGF/Met pathway that conveys metabolic signaling from macrophages to hepatocytes in hepatic steatosis and insulin resistance and provide potential new therapeutic strategies for NAFLD and T2DM.

Emerging roles for the amyloid precursor protein and derived peptides in the regulation of cellular and systemic metabolism

The amyloid precursor protein (APP) is a transmembrane protein that can be cleaved by proteases through two different pathways to yield a number of small peptides, each with distinct physiological properties and functions. It has been extensively studied in the context of Alzheimer's disease, with the APP-derived amyloid β (Aβ) peptide being a major constituent of the amyloid plaques observed in this disease. It has been known for some time that APP can regulate neuronal metabolism; however, the present review examines the evidence indicating that APP and its peptides can also regulate key metabolic processes such as insulin action, lipid synthesis and storage and mitochondrial function in peripheral tissues. This review presents the hypothesis that amyloidogenic processing of APP in peripheral tissues plays a key role in the response to nutrient excess and that this could contribute to the pathogenesis of metabolic diseases such as obesity and type 2 diabetes (T2D).

Hepatostat: Liver regeneration and normal liver tissue maintenance

In contrast to all other organs, liver-to-body-weight ratio needs to be maintained always at 100% of what is required for body homeostasis. Adjustment of liver size to 100% of what is required for homeostasis has been called "hepatostat." Removal of a portion of any other organ is followed with local regeneration of a limited degree, but it never attempts to reach 100% of the original size. The complex mechanisms involved in this uniquely hepatic process encompass a variety of regenerative pathways that are specific to different types of injury. The most studied form of liver regeneration (LR) is that occurring after loss of hepatocytes in a single acute injury, such as rodent LR after two-thirds partial hepatectomy or administration of damaging chemicals (CCl₄ , acetaminophen, etc.). Alternative regenerative pathways become activated when normal regeneration is thwarted and trigger the appearance of "progenitor" cells. Chronic loss of hepatocytes is associated with regenerative efforts characterized by continual hepatocyte proliferation and often has adverse consequences (development of cirrhosis or liver cancer). Even though a very few hepatocytes proliferate at any given time in normal liver, the mechanisms involved in the maintenance of liver weight by this slow process in the absence of liver injury are not as well understood. (Hepatology 2017;65:1384-1392).

Hepatocyte Growth Factor Prevented High-Fat Diet-Induced Obesity and Improved Insulin Resistance in Mice

Obesity and its associated chronic inflammation in adipose tissue initiate insulin resistance, which is related to several pathologies including hypertension and atherosclerosis. Previous reports demonstrated that circulating hepatocyte growth factor (HGF) level was associated with obesity and type 2 diabetes. However, its precise role in obesity and related-pathology is unclear. In this experiment, cardiac-specific over-expression of human HGF in mice (HGF-Tg mice) which showed 4–5 times higher serum HGF levels than wild-type mice were used. While body weight in wild-type mice fed with high fat diet (HFD) for 14 weeks was significantly increased accompanied with insulin resistance, HGF-Tg mice prevented body weight gain and insulin resistance. The accumulation of macrophages and elevated levels of inflammatory mediators in adipose tissue were significantly inhibited in HGF-Tg mice as compared to wild-type mice. The HFD-induced obesity in wild-type mice treated with HGF-neutralizing antibody showed an exacerbated response to the glucose tolerance test. These gain-of-function and loss-of-function studies demonstrated that the elevated HGF level induced by HFD have protective role against obesity and insulin resistance.

Levels of metabolic markers in drug-naive prediabetic and type 2 diabetic patients

AIMS

Type 2 diabetes mellitus (T2DM) and prediabetes (pre-DM) are associated with changes in levels of metabolic markers. The main aim of this study is to compare the levels of omentin, irisin, endothelin-1, nesfatin, hepatocyte growth factor (HGF), fibroblast growth factor, and oxytocin (OXT) between normoglycemic and pre-DM/T2DM obese Jordanian patients.

METHODS

One hundred and ninety-eight adult Jordanian subjects were recruited. Demographic data and clinical parameters were collected. The serum levels of biomarkers were measured by enzymatic assay procedure.

RESULTS

Compared to normoglycemic (95 subjects), pre-DM/T2DM (103 subjects) displayed higher HGF (ng/ml) = 78.8 (71.4-104) versus 55.9 (45.3-66.6), p < 0.0001; and nesfatin (ng/ml) = 0.5 (0.4-0.7) versus 0.2 (0.1-0.4), p < 0.0001; betatrophin (ng/ml) = 1.2 (0.8-1.6) versus 0.22 (0.15-0.41), p < 0.0001. On the other hand, they had lower levels of omentin (ng/ml) = 2.1 (0.9-3.3) versus 3.6 (2.0-6.4), p < 0.0001, irisin (ng/ml) = 113.7 (88.9-142.9) versus 132.6 (110.7-147.8), p < 0.0001; and oxytocin (pg/ml) = 1077.9 (667.3-1506.0) versus 2180.1 (1464.5-2795.6), p < 0.0001; respectively. In comparison, FGF-21 (ng/ml) = 0.3 (0.2-0.5) versus 0.2 (0.1-0.4), and endothelin (pg/ml) = 2.7 (1.3-5.2) versus 2.8 (1.6-5.6) did not differ between the two groups (p > 0.05).

CONCLUSIONS

In the present study, patients with pre-DM and T2DM have higher serum levels of metabolic HGF, nesfatin, and betatrophin and lower levels of omentin, irisin, and OXT. Future longitudinal and interventional studies are required to confirm the utility of these markers as novel progression or therapeutic targets in the pharmacotherapy of diabetes.

Macrophage Stimulating Protein Enhances Hepatic Inflammation in a NASH Model

Non-alcoholic steatohepatitis (NASH) is a common liver disease characterized by hepatic lipid accumulation (steatosis) and inflammation. Currently, therapeutic options are poor and the long-term burden to society is constantly increasing. Previously, macrophage stimulating protein (MSP)—a serum protein mainly secreted by liver—was shown to inhibit oxidized low-density lipoprotein (OxLDL)/lipopolysaccharides (LPS)-induced inflammation in mouse macrophages. Additionally, MSP could reduce palmitic acid (PA)-induced lipid accumulation and lipogenesis in the HepG2 cell line. Altogether, these data suggest MSP as a suppressor for metabolic inflammation. However, so far the potential of MSP to be used as a treatment for NASH was not investigated. We hypothesized that MSP reduces lipid accumulation and hepatic inflammation. To investigate the effects of MSP in the early stage of NASH, low-density lipoprotein receptor (Ldlr^-/-) mice were fed either a regular chow or a high fat, high cholesterol (HFC) diet for 7 days. Recombinant MSP or saline (control) was administrated to the mice by utilizing subcutaneously-implanted osmotic mini-pumps for the last 4 days. As expected, mice fed an HFC diet showed increased plasma and hepatic lipid accumulation, as well as enhanced hepatic inflammation, compared with chow-fed controls. Upon MSP administration, the rise in cholesterol and triglyceride levels after an HFC diet remained unaltered. Surprisingly, while hepatic macrophage and neutrophil infiltration was similar between the groups, MSP-treated mice showed increased gene expression of pro-inflammatory and pro-apoptotic mediators in the liver, compared with saline-treated controls. Contrary to our expectations, MSP did not ameliorate NASH. Observed changes in inflammatory gene expression suggest that further research is needed to clarify the long-term effects of MSP.

Autism-specific maternal anti-fetal brain autoantibodies are associated with metabolic conditions

Approximately 23% of mothers of children with autism spectrum disorder (ASD) produce specific patterns of autoantibodies to fetal brain proteins that have been detected in only 1% of mothers of typically developing children. The biological mechanisms underlying the development of ASD-specific maternal autoantibodies are poorly understood. We sought to determine whether ASD-specific maternal autoantibodies identified postnatally were associated with metabolic conditions (MCs) during gestation. Participants were 227 mothers of 2-5 year old children with confirmed ASD, enrolled in CHARGE (Childhood Autism Risk from Genetics and the Environment) between January 2003 and April 2008, and from whom blood samples were collected and analyzed for anti-fetal brain autoantibodies (Ab+). MCs included diabetes, hypertensive disorders, and prepregnancy obesity or overweight, ascertained from medical records or structured telephone interviews. Log-linear regression models were performed to estimate prevalence ratios and 95% confidence intervals (CI) based on robust standard errors. Fifty-six (25%) mothers were Ab+. Ab+ prevalence was higher among mothers with diabetes, hypertensive disorders, or overweight compared to healthy mothers, but differences were not statistically significant. In a subset of 145 mothers whose children exhibited severe ASD (31 Ab+), those diagnosed with type 2 or gestational diabetes were 2.7-fold more likely to be Ab+ (95% CI 1.1, 6.6), controlling for delivery payer and smoking. Gestational diabetes specifically was associated with a 3.2-fold increased Ab+ prevalence (95% CI 1.2, 8.6). In this exploratory study, mothers whose children had severe ASD and who experienced diabetes were more likely to have anti-fetal brain autoantibodies 2-5 years later. Autism Res 2017, 10: 89-98. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Serial changes of cytokines and growth factors in peripheral circulation after right lobe donor hepatectomy

Cytokines and growth factors have prominent roles in liver regeneration. The aim of this study was to evaluate the biological markers of liver regeneration in healthy donors undergoing right lobe donor hepatectomy for living donor liver transplantation. Twenty-five voluntary liver donors were enrolled. Peripheral blood samples were taken a day before the operation and on postoperative days (PODs) 1, 3, 7, 14, and 42. Levels of hepatocyte growth factor (HGF), interleukin (IL) 6, tumor necrosis factor α (TNF-α), thrombopoietin (TPO), transforming growth factor β1 (TGF-β1), interferon (IFN) α, and IFNγ were monitored. The remnant liver volume (RLV) before surgery and regeneration liver volume (RgV) on POD 14 were calculated on computed tomography (CT). RgV/RLV ratio was correlated with the remnant-liver-volume-to-body-weight ratio (RLVBWR). Inverse correlation was observed between RgV/RLV and RLVBWR (r(2) = 0.61; P < 0.001). There was a significant rise of HGF on POD 1 (P = 0.001), POD 7 (P = 0.049), and POD 14 (P = 0.04). TNF-α was elevated on POD 1 (P = 0.004). The levels of IL 6 (P < 0.001) and TPO (P < 0.001) were higher from POD 1 to POD 42. IFNα was higher on POD 14 (P = 0.003) and POD 42 (P = 0.001). There was a significant fall of IFNγ on POD 1 (P = 0.01) and increase on POD 14 (P = 0.04). The levels of TGF-β1 were higher on POD 14 (P = 0.008) and on POD 42 (P = 0.002). In conclusion, HGF, IL 6, TNF-α, and TPO are involved in the early phase, whereas TGF-β1 and IFN are involved in the termination phase of liver regeneration. Liver regeneration was observed to be higher in donors with low RLVBWR.

Circulating level of hepatocyte growth factor predicts incidence of type 2 diabetes mellitus: The Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Hepatocyte growth factor (HGF) is a pleotropic factor posited to have metabolic homeostatic properties. The purpose of this study is to examine whether level of HGF is associated with the development of type 2 diabetes.

METHODS

Data from the Multi-Ethnic Study of Atherosclerosis (MESA) were used to examine the prospective association between serum level of HGF and incident diabetes. Fasting HGF was measured at Exam 1 (2000-2002) in 5395 participants free from diabetes (61.5±10.2 years old) and incidence of diabetes was determined at four subsequent follow-up exams over 12 years. Hazard ratios (HR) for incident diabetes were estimated according to 1 standard deviation (SD) unit increment of HGF (1 SD=26 μg/l), before and after adjustment for age, sex, race/ethnicity, education, study center, smoking status, alcohol consumption, body mass index, waist circumference, fasting glucose and insulin, C-reactive protein, and interleukin-6 levels.

RESULTS

A 1 SD increment of baseline HGF was associated with a 46% (95% CI=1.37, 1.56) increased risk of diabetes before adjustment. After adjustment, diabetes risk per 1 SD increment of HGF was attenuated but remained significantly increased (HR=1.21; 95% CI=1.12, 1.32). Men had a significantly greater HR compared to women per equivalent increase of HGF (p-value for sex interaction=0.04). There was no evidence of effect modification by race/ethnicity.

CONCLUSIONS

This study advances understanding from cross-sectional studies and investigation of incident insulin resistance, demonstrating higher level of HGF is associated with incident diabetes and may reflect a unique type of impaired metabolism.