Anti-apoptotic signaling by hepatocyte growth factor/Met via the phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase pathways

Molecular Pathways Governing the Termination of Liver Regeneration

The liver has the unique capacity to regenerate, and up to 70% of the liver can be removed without detrimental consequences to the organism. Liver regeneration is a complex process involving multiple signaling networks and organs. Liver regeneration proceeds through three phases: the initiation phase, the growth phase, and the termination phase. Termination of liver regeneration occurs when the liver reaches a liver-to-body weight that is required for homeostasis, the so-called "hepatostat." The initiation and growth phases have been the subject of many studies. The molecular pathways that govern the termination phase, however, remain to be fully elucidated. This review summarizes the pathways and molecules that signal the cessation of liver regrowth after partial hepatectomy and answers the question, "What factors drive the hepatostat?" SIGNIFICANCE STATEMENT: Unraveling the pathways underlying the cessation of liver regeneration enables the identification of druggable targets that will allow us to gain pharmacological control over liver regeneration. For these purposes, it would be useful to understand why the regenerative capacity of the liver is hampered under certain pathological circumstances so as to artificially modulate the regenerative processes (e.g., by blocking the cessation pathways) to improve clinical outcomes and safeguard the patient's life.

Evaluation of different media compositions promoting hepatocyte differentiation in the canine liver organoid model

Organoids are 3-dimensional (3D) self-assembled structures capable of replicating the microanatomy and physiology of the epithelial components of their organ of origin. Adult stem cell (ASC) derived organoids from the liver have previously been shown to differentiate into primarily mature cholangiocytes, and their partial differentiation into functional hepatocytes can be promoted using specific media compositions. While full morphological differentiation of mature hepatocytes from ASCs has not yet been reported for any species, the functional differentiation can be approximated using various media compositions. Six differentiation media formulations from published studies on hepatic organoids were used for the differentiation protocol. Target species for these protocols were humans, mice, cats, and dogs, and encompassed various combinations and concentrations of four major hepatocyte media components: Bone morphogenetic protein 7 (BMP7), Fibroblast Growth Factor 19 (FGF19), Dexamethasone (Dex), and Gamma-Secretase Inhibitor IX (DAPT). Additionally, removing R-spondin from basic organoid media has previously been shown to drive the differentiation of ASC into mature hepatocytes. Differentiation media (N = 20) were designed to encompass combinations of the four major hepatocyte media components. The preferred differentiation of ASC-derived organoids from liver tissue into mature hepatocytes over cholangiocytes was confirmed by albumin production in the culture supernatant. Out of the twenty media compositions tested, six media resulted in the production of the highest amounts of albumin in the supernatant of the organoids. The cell lines cultured using these six media were further characterized via histological staining, transmission electron microscopy, RNA in situ hybridization, analysis of gene expression patterns, immunofluorescence, and label-free proteomics. The results indicate that preferential hepatocyte maturation from canine ADC-derived organoids from liver tissue is mainly driven by Dexamethasone and DAPT components. FGF19 did not enhance organoid differentiation but improved cell culture survival. Furthermore, we confirm that removing R-spondin from the media is crucial for establishing mature hepatic organoid cultures.

Fosgonimeton attenuates amyloid-beta toxicity in preclinical models of Alzheimer's disease

Positive modulation of hepatocyte growth factor (HGF) signaling may represent a promising therapeutic strategy for Alzheimer's disease (AD) based on its multimodal neurotrophic, neuroprotective, and anti-inflammatory effects addressing the complex pathophysiology of neurodegeneration. Fosgonimeton is a small-molecule positive modulator of the HGF system that has demonstrated neurotrophic and pro-cognitive effects in preclinical models of dementia. Herein, we evaluate the neuroprotective potential of fosgonimeton, or its active metabolite, fosgo-AM, in amyloid-beta (Aβ)-driven preclinical models of AD, providing mechanistic insight into its mode of action. In primary rat cortical neurons challenged with Aβ (Aβ1-42), fosgo-AM treatment significantly improved neuronal survival, protected neurite networks, and reduced tau hyperphosphorylation. Interrogation of intracellular events indicated that cortical neurons treated with fosgo-AM exhibited a significant decrease in mitochondrial oxidative stress and cytochrome c release. Following Aβ injury, fosgo-AM significantly enhanced activation of pro-survival effectors ERK and AKT, and reduced activity of GSK3β, one of the main kinases involved in tau hyperphosphorylation. Fosgo-AM also mitigated Aβ-induced deficits in Unc-like kinase 1 (ULK1) and Beclin-1, suggesting a potential effect on autophagy. Treatment with fosgo-AM protected cortical neurons from glutamate excitotoxicity, and such effects were abolished in the presence of an AKT or MEK/ERK inhibitor. In vivo, fosgonimeton administration led to functional improvement in an intracerebroventricular Aβ25-35 rat model of AD, as it significantly rescued cognitive function in the passive avoidance test. Together, our data demonstrate the ability of fosgonimeton to counteract mechanisms of Aβ-induced toxicity. Fosgonimeton is currently in clinical trials for mild-to-moderate AD (NCT04488419; NCT04886063).

ATH-1105, a small-molecule positive modulator of the neurotrophic HGF system, is neuroprotective, preserves neuromotor function, and extends survival in preclinical models of ALS

Introduction

Amyotrophic lateral sclerosis (ALS), a progressive and fatal neurodegenerative disorder, primarily affects the motor neurons of the brain and spinal cord. Like other neurodegenerative conditions, ongoing pathological processes such as increased inflammation, excitotoxicity, and protein accumulation contribute to neuronal death. Hepatocyte growth factor (HGF) signaling through the MET receptor promotes pro-survival, anti-apoptotic, and anti-inflammatory effects in multiple cell types, including the neurons and support cells of the nervous system. This pleiotropic system is therefore a potential therapeutic target for treatment of neurodegenerative disorders such as ALS. Here, we test the effects of ATH-1105, a small-molecule positive modulator of the HGF signaling system, in preclinical models of ALS.

Methods

In vitro, the impact of ATH-1105 on HGF-mediated signaling was assessed via phosphorylation assays for MET, extracellular signal-regulated kinase (ERK), and protein kinase B (AKT). Neuroprotective effects of ATH-1105 were evaluated in rat primary neuron models including spinal motor neurons, motor neuron-astrocyte cocultures, and motor neuron-human muscle cocultures. The anti-inflammatory effects of ATH-1105 were evaluated in microglia- and macrophage-like cell systems exposed to lipopolysaccharide (LPS). In vivo, the impact of daily oral treatment with ATH-1105 was evaluated in Prp-TDP43A315T hemizygous transgenic ALS mice.

Results

In vitro, ATH-1105 augmented phosphorylation of MET, ERK, and AKT. ATH-1105 attenuated glutamate-mediated excitotoxicity in primary motor neurons and motor neuron- astrocyte cocultures, and had protective effects on motor neurons and neuromuscular junctions in motor neuron-muscle cocultures. ATH-1105 mitigated LPS-induced inflammation in microglia- and macrophage-like cell systems. In vivo, ATH-1105 treatment resulted in improved motor and nerve function, sciatic nerve axon and myelin integrity, and survival in ALS mice. Treatment with ATH-1105 also led to reductions in levels of plasma biomarkers of inflammation and neurodegeneration, along with decreased pathological protein accumulation (phospho-TDP-43) in the sciatic nerve. Additionally, both early intervention (treatment initiation at 1 month of age) and delayed intervention (treatment initiation at 2 months of age) with ATH-1105 produced benefits in this preclinical model of ALS.

Discussion

The consistent neuroprotective and anti-inflammatory effects demonstrated by ATH-1105 preclinically provide a compelling rationale for therapeutic interventions that leverage the positive modulation of the HGF pathway as a treatment for ALS.

CD1d protects against hepatocyte apoptosis in non-alcoholic steatohepatitis

BACKGROUND & AIMS

Hepatocyte apoptosis, a well-defined form of cell death in non-alcoholic steatohepatitis (NASH), is considered the primary cause of liver inflammation and fibrosis. However, the mechanisms underlying the regulation of hepatocyte apoptosis in NASH remain largely unclear. We explored the anti-apoptotic effect of hepatocyte CD1d in NASH.

METHODS

Hepatocyte CD1d expression was analyzed in patients with NASH and mouse models. Hepatocyte-specific gene overexpression or knockdown and anti-CD1d crosslinking were used to investigate the anti-apoptotic effect of hepatocyte CD1d on lipotoxicity-, Fas-, and concanavalin (ConA)-mediated liver injuries. A high-fat diet, a methionine-choline-deficient diet, a Fas agonist, and ConA were used to induce lipotoxic and/or apoptotic liver injuries. Palmitic acid was used to mimic lipotoxicity-induced apoptosis in vitro.

RESULTS

We identified a dramatic decrease in CD1d expression in hepatocytes of patients with NASH and mouse models. Hepatocyte-specific CD1d overexpression and knockdown experiments collectively demonstrated that hepatocyte CD1d protected against hepatocyte apoptosis and alleviated hepatic inflammation and injuries in NASH mice. Furthermore, decreased JAK2-STAT3 signaling was observed in NASH patient livers. Mechanistically, anti-CD1d crosslinking on hepatocytes induced tyrosine phosphorylation of the CD1d cytoplasmic tail, leading to the recruitment and phosphorylation of JAK2. Phosphorylated JAK2 activated STAT3 and subsequently reduced apoptosis in hepatocytes, which was associated with an increase in anti-apoptotic effectors (Bcl-xL and Mcl-1) and a decrease in pro-apoptotic effectors (cleaved-caspase 3/7). Moreover, anti-CD1d crosslinking effectively protected against Fas- or ConA-mediated hepatocyte apoptosis and liver injury in mice.

CONCLUSIONS

Our study uncovered a previously unrecognized anti-apoptotic CD1d-JAK2-STAT3 axis in hepatocytes that conferred hepatoprotection and highlighted the potential of hepatocyte CD1d-directed therapy for liver injury and fibrosis in NASH, as well as in other liver diseases associated with hepatocyte apoptosis.

IMPACT AND IMPLICATIONS

Excessive and/or sustained hepatocyte apoptosis is critical in driving liver inflammation and injury. The mechanisms underlying the regulation of hepatocyte apoptosis in non-alcoholic steatohepatitis (NASH) remain largely unclear. Here, we found that CD1d expression in hepatocytes substantially decreases and negatively correlates with the severity of liver injury in patients with NASH. We further revealed a previously unrecognized anti-apoptotic CD1d-JAK2-STAT3 signaling axis in hepatocytes, which confers significant protection against liver injury in NASH and acute liver diseases. Thus, hepatocyte CD1d-targeted therapy could be a promising strategy to manipulate liver injury in both NASH and other hepatocyte apoptosis-related liver diseases.

Targeting MET in NSCLC: An Ever-Expanding Territory

MET protooncogene (MET) alterations are known driver oncogenes in NSCLC. Since the identification of MET as a potential therapeutic target, extensive clinical trials have been performed. As a result, MET-targeted therapies, including MET tyrosine kinase inhibitors, monoclonal antibodies, and MET antibody-drug conjugates now play important roles in the standard treatment of MET-altered NSCLC; they have considerably improved the outcomes of patients with tumors that harbor MET oncogenic drivers. Although clinical agents are currently available and numerous other options are in development, particular challenges in the field require attention. For example, the therapeutic efficacy of each drug remains unsatisfactory, and concomitantly, the resistance mechanisms are not fully understood. Thus, there is an urgent need for optimal drug sequencing and combinations, along with a thorough understanding of treatment resistance. In this review, we describe the current landscape of pertinent clinical trials focusing on MET-targeted strategies and discuss future developmental directions in this rapidly expanding field.

HGF facilitates methylation of MEG3, potentially implicated in vemurafenib resistance in melanoma

BACKGROUND

Melanoma, a frequently encountered cutaneous malignancy characterized by a poor prognosis, persists in presenting formidable challenges despite the advancement in molecularly targeted drugs designed to improve survival rates significantly. Unfortunately, as more therapeutic choices have developed over time, the gradual emergence of drug resistance has become a notable impediment to the effectiveness of these therapeutic interventions. The hepatocyte growth factor (HGF)/c-met signaling pathway has attracted considerable attention, associated with drug resistance stemming from multiple potential mutations within the c-met gene. The activation of the HGF/c-met pathway operates in an autocrine manner in melanoma. Notably, a key player in the regulatory orchestration of HGF/c-met activation is the long non-coding RNA MEG3.

METHODS

Melanoma tissues were collected to measure MEG3 expression. In vitro validation was performed on MEG3 to prove its oncogenic roles. Bioinformatic analyses were conducted on the TCGA database to build the MEG3-related score. The immune characteristics and mutation features of the MEG3-related score were explored.

RESULTS

We revealed a negative correlation between HGF and MEG3. In melanoma cells, HGF inhibited MEG3 expression by augmenting the methylation of the MEG3 promoter. Significantly, MEG3 exhibits a suppressive impact on the proliferation and migration of melanoma cells, concurrently inhibiting c-met expression. Moreover, a predictive model centered around MEG3 demonstrates notable efficacy in forecasting critical prognostic indicators, immunological profiles, and mutation statuses among melanoma patients.

CONCLUSIONS

The present study highlights the potential of MEG3 as a pivotal regulator of c-met, establishing it as a promising candidate for targeted drug development in the ongoing pursuit of effective therapeutic interventions.

Inhibition of Cell Apoptosis by Apicomplexan Protozoa-Host Interaction in the Early Stage of Infection

Apicomplexan protozoa, which are a group of specialized intracellular parasitic protozoa, infect humans and other animals and cause a variety of diseases. The lack of research on the interaction mechanism between Apicomplexan protozoa and their hosts is a key factor restricting the development of new drugs and vaccines. In the early stages of infection, cell apoptosis is inhibited by Apicomplexan protozoa through their interaction with the host cells; thereby, the survival and reproduction of Apicomplexan protozoa in host cells is promoted. In this review, the key virulence proteins and pathways are introduced regarding the inhibition of cell apoptosis by the interaction between the protozoa and their host during the early stage of Apicomplexan protozoa infection. It provides a theoretical basis for the development of drugs or vaccines for protozoal diseases.

Clinicopathological and prognostic values of MET expression in pancreatic adenocarcinoma based on bioinformatics analysis

Pancreatic adenocarcinoma (PAAD) is regarded as one of the most lethiferous cancers worldwide because treatment of pancreatic cancer remains challenging and mostly palliative. Little progress had been made to select certain reliable biomarkers as clinical prognosis. In this context, GSE28735 and GSE16515 were obtained from the Gene Expression Omnibus (GEO). GEO2R tool was used to recognize differentially expressed genes (DEGs). 351 DEGs were screened which included 230 up-regulated genes and 121 down-regulated genes. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to analyze the DEGs and associated signal pathways in the DAVID database. A protein-protein interaction (PPI) network was then constructed to screen 10 hub genes by STRING database and Cityscape software. Analyses of 10 hub genes were performed on GEPIA database and GSCA database, which revealed that MET was high expressed and significantly associated with survival of PAAD patients. Immunohistochemical staining showed that MET was higher expressed in PAAD tissues than adjacent tissues in 20 samples. The clinicopathological analysis revealed that high expression of MET was associated with the degree of differentiation, lymph node metastasis, vascular cancer thrombus and nerve invasion in PAAD tissues (P < .05). Furthermore, the Tumor Immune Estimation Resource (TIMER) database analyzed the correlation between the MET expression level and immune infiltration levels, which elucidated that MET expression was appreciably positively correlated with the infiltration levels of myeloid-derived suppressor cells (MDSCs). Here, these results strongly indicate MET is an unique prognostic biomarker. Its expression level is correlated with certain clinicopathological features and immune cell infiltration.

Advances in stem cell therapy for peritoneal fibrosis: from mechanisms to therapeutics

Peritoneal fibrosis (PF) is a pathophysiological condition caused by a variety of pathogenic factors. The most important features of PF are mesothelial-mesenchymal transition and accumulation of activated (myo-)fibroblasts, which hinder effective treatment; thus, it is critical to identify other practical approaches. Recently, stem cell (SC) therapy has been indicated to be a potential strategy for this disease. Increasing evidence suggests that many kinds of SCs alleviate PF mainly by differentiating into mesothelial cells; secreting cytokines and extracellular vesicles; or modulating immune cells, particularly macrophages. However, there are relatively few articles summarizing research in this direction. In this review, we summarize the risk factors for PF and discuss the therapeutic roles of SCs from different sources. In addition, we outline effective approaches and potential mechanisms of SC therapy for PF. We hope that our review of articles in this area will provide further inspiration for research on the use of SCs in PF treatment.

Tools and techniques for the discovery of therapeutic aptamers: recent advances

INTRODUCTION

The pursuit of novel therapeutic agents for serious diseases such as cancer has been a global endeavor. Aptamers characteristic of high affinity, programmability, low immunogenicity, and rapid permeability hold great promise for the treatment of diseases. Yet obtaining the approval for therapeutic aptamers remains challenging. Consequently, researchers are increasingly devoted to exploring innovative strategies and technologies to advance the development of these therapeutic aptamers.

AREAS COVERED

The authors provide a comprehensive summary of the recent progress of the SELEX (Systematic Evolution of Ligands by EXponential enrichment) technique, and how the integration of modern tools has facilitated the identification of therapeutic aptamers. Additionally, the engineering of aptamers to enhance their functional attributes, such as inhibiting and targeting, is discussed, demonstrating the potential to broaden their scope of utility.

EXPERT OPINION

The grand potential of aptamers and the insufficient development of relevant drugs have spurred countless efforts for stimulating their discovery and application in the therapeutic field. While SELEX techniques have undergone significant developments with the aid of advanced analysis instruments and ingeniously updated aptameric engineering strategies, several challenges still impede their clinical translation. A key challenge lies in the insufficient understanding of binding conformation and susceptibility to degradation under physiological conditions. Despite the hurdles, our opinion is optimistic. With continued progress in overcoming these obstacles, the widespread utilization of aptamers for clinical therapy is envisioned to become a reality soon.

Hepatocyte growth factor mimetic confers protection from aminoglycoside-induced hair cell death in vitro

Loss of sensory hair cells from exposure to certain licit drugs, such as aminoglycoside antibiotics, can result in permanent hearing damage. Exogenous application of the neurotrophic molecule hepatocyte growth factor (HGF) promotes neuronal cell survival in a variety of contexts, including protecting hair cells from aminoglycoside ototoxicity. HGF itself is not an ideal therapeutic due to a short half-life and limited blood-brain barrier permeability. MM-201 is a chemically stable, blood-brain barrier permeable, synthetic HGF mimetic that serves as a functional ligand to activate the HGF receptor and its downstream signaling cascade. We previously demonstrated that MM-201 robustly protects zebrafish lateral line hair cells from aminoglycoside ototoxicity. Here, we examined the ability of MM-201 to protect mammalian sensory hair cells from aminoglycoside damage to further evaluate MM-201's clinical potential. We found that MM-201 exhibited dose-dependent protection from neomycin and gentamicin ototoxicity in mature mouse utricular explants. MM-201's protection was reduced following inhibition of mTOR, a downstream target of HGF receptor activation, implicating the activation of endogenous intracellular substrates by MM-201 as critical for the observed protection. We then asked if MM-201 altered the bactericidal properties of aminoglycosides. Using either plate or liquid growth assays we found that MM-201 did not alter the bactericidal efficacy of aminoglycoside antibiotics at therapeutically relevant concentrations. We therefore assessed the protective capacity of MM-201 in an in vivo mouse model of kanamycin ototoxicity. In contrast to our in vitro data, MM-201 did not attenuate kanamycin ototoxicity in vivo. Further, we found that MM-201 was ototoxic to mice across the dose range tested here. These data suggest species- and tissue-specific differences in otoprotective capacity. Next generation HGF mimetics are in clinical trials for neurodegenerative diseases and show excellent safety profiles, but neither preclinical studies nor clinical trials have examined hearing loss as a potential consequence of pharmaceutical HGF activation. Further research is needed to determine the consequences of systemic MM-201 application on the auditory system.

Blocking the HGF-MET pathway induces resolution of neutrophilic inflammation by promoting neutrophil apoptosis and efferocytosis

Inflammation resolution is an active process that involves cellular events such as apoptosis and efferocytosis, which are key steps in the restoration of tissue homeostasis. Hepatocyte growth factor (HGF) is a growth factor mostly produced by mesenchymal-origin cells and has been described to act via MET receptor tyrosine kinase. The HGF/MET axis is essential for determining the progression and severity of inflammatory and immune-mediated disorders. Here, we investigated the effect of blocking the HGF/MET signalling pathway by PF-04217903 on the resolution of established models of neutrophilic inflammation. In a self-resolving model of gout induced by MSU crystals, HGF expression on periarticular tissue peaked at 12 h, the same time point that neutrophils reach their maximal accumulation in the joints. The HGF/MET axis was activated in this model, as demonstrated by increased levels of MET phosphorylation in neutrophils (Ly6G⁺ cells). In addition, the number of neutrophils was reduced in the knee exudate after PF-04217903 treatment, an effect accompanied by increased neutrophil apoptosis and efferocytosis and enhanced expression of Annexin A1, a key molecule for inflammation resolution. Reduced MPO activity, IL-1β and CXCL1 levels were also observed in periarticular tissue. Importantly, PF-04217903 reduced the histopathological score and hypernociceptive response. Similar findings were obtained in LPS-induced neutrophilic pleurisy. In human neutrophils, the combined use of LPS and HGF increased MET phosphorylation and provided a prosurvival signal, whereas blocking MET with PF-04217903 induced caspase-dependent neutrophil apoptosis. Taken together, these data demonstrate that blocking HGF/MET signalling may be a potential therapeutic strategy for inducing the resolution of neutrophilic inflammatory responses.

Options of Therapeutics and Novel Delivery Systems of Drugs for the Treatment of Melanoma

Melanoma is one of the most severe cancerous diseases. The cells employ multiple signaling pathways, such as ERK, HGF/c-MET, WNT, and COX-2 to cause the cell proliferation, survival, and metastasis. Treatment of melanoma, including surgery, chemotherapy, immunotherapy, radiation, and targeted therapy, is based on 4 major or 11 substages of the disease. Fourteen drugs, including dacarbazine, interferon α-2b, interleukin-12, ipilimumab, peginterferon α-2b, vemurafenib, trametinib, talimogene laherparepvec, cobimetinib, pembrolizumab, dabrafenib, binimetinib, encorafenib, and nivolumab, have been approved by the FDA for the treatment of melanoma. All of them are in conventional dosage forms of injection solutions, suspensions, oral tablets, or capsules. Major drawbacks of the treatment are side effects of the drugs and patients' incompliance to them. These are consequences of high doses and long-term treatments for the diseases. Currently more than 350 NCI-registered clinical trials are being carried out to treat advanced and/or metastatic melanoma using novel treatment methods, such as immune cell therapy, cancer vaccines, and new therapeutic targets. In addition, novel delivery systems using biomaterials of the approved drugs have been developed attempting to increase the drug delivery, targeting, stability, bioavailability, thus potentially reducing the toxicity and increasing the treatment effectiveness. Nanoparticles and liposomes have been emerging as advanced delivery systems which can improve drug stability and systemic circulation time. In this review, the most recent findings in the options for treatment and development of novel drug delivery systems for the treatment of melanoma are comprehensively discussed.

Spatial modeling reveals nuclear phosphorylation and subcellular shuttling of YAP upon drug-induced liver injury

The Hippo signaling pathway controls cell proliferation and tissue regeneration via its transcriptional effectors yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ). The canonical pathway topology is characterized by sequential phosphorylation of kinases in the cytoplasm that defines the subcellular localization of YAP and TAZ. However, the molecular mechanisms controlling the nuclear/cytoplasmic shuttling dynamics of both factors under physiological and tissue-damaging conditions are poorly understood. By implementing experimental in vitro data, partial differential equation modeling, as well as automated image analysis, we demonstrate that nuclear phosphorylation contributes to differences between YAP and TAZ localization in the nucleus and cytoplasm. Treatment of hepatocyte-derived cells with hepatotoxic acetaminophen (APAP) induces a biphasic protein phosphorylation eventually leading to nuclear protein enrichment of YAP but not TAZ. APAP-dependent regulation of nuclear/cytoplasmic YAP shuttling is not an unspecific cellular response but relies on the sequential induction of reactive oxygen species (ROS), RAC-alpha serine/threonine-protein kinase (AKT, synonym: protein kinase B), as well as elevated nuclear interaction between YAP and AKT. Mouse experiments confirm this sequence of events illustrated by the expression of ROS-, AKT-, and YAP-specific gene signatures upon APAP administration. In summary, our data illustrate the importance of nuclear processes in the regulation of Hippo pathway activity. YAP and TAZ exhibit different shuttling dynamics, which explains distinct cellular responses of both factors under physiological and tissue-damaging conditions.

A renewed concept on the MAPK signaling pathway in cancers: Polyphenols as a choice of therapeutics

Abnormalities in the mitogen-activated protein kinase (MAPK) signaling pathway are a key contributor to the carcinogenesis process and have therefore been implicated in several aspects of tumorigenesis, including cell differentiation, proliferation, invasion, angiogenesis, apoptosis, and metastasis. This pathway offers multiple molecular targets that may be modulated for anticancer activity and is of great interest for several malignancies. Polyphenols from various dietary sources have been observed to interfere with certain aspects of this pathway and consequently play a substantial role in the development and progression of cancer by suppressing cell growth, inactivating carcinogens, blocking angiogenesis, causing cell death, and changing immunity. A good number of polyphenolic compounds have shown promising outcomes in numerous pieces of research and are currently being investigated clinically to treat cancer patients. The current study concentrates on the role of the MAPK pathway in the development and metastasis of cancer, with particular emphasis on dietary polyphenolic compounds that influence the different MAPK sub-pathways to obtain an anticancer effect. This study aims to convey an overview of the various aspects of the MAPK pathway in cancer development and invasion, as well as a review of the advances achieved in the development of polyphenols to modulate the MAPK signaling pathway for better treatment of cancer.

Transglutaminase 2 enhances hepatocyte growth factor signaling to drive the mesothelioma cancer cell phenotype

Transglutaminase 2 (TG2) is an important mesothelioma cancer cell survival protein. However, the mechanism whereby TG2 maintains mesothelioma cell survival is not well understood. We present studies showing that TG2 drives hepatocyte growth factor (HGF)-dependent MET receptor signaling to maintain the aggressive mesothelioma cancer phenotype. TG2 increases HGF and MET messenger RNA and protein levels to enhance MET signaling. TG2 inactivation reduces MET tyrosine kinase activity to reduce cancer cell spheroid formation, invasion and migration. We also confirm that HGF/MET signaling is a biologically important mediator of TG2 action. Reducing MET level using genetic methods or treatment with MET inhibitors reduces spheroid formation, invasion and migration and this is associated with reduced MEK1/2 and ERK1/2. In addition, MEK1/2 and ERK1/2 inhibitors suppress the cancer phenotype. Moreover, MET knockout mesothelioma cells form 10-fold smaller tumors compared to wild-type cells and these tumors display reduced MET, MEK1/2, and ERK1/2 activity. These findings suggest that TG2 maintains HGF and MET levels in cultured mesothelioma cells and tumors to drive HGF/MET, MEK1/2, and ERK1/2 signaling to maintain the aggressive mesothelioma cancer phenotype.

Bacterial inhibition of Fas-mediated killing promotes neuroinvasion and persistence

Infections of the central nervous system are among the most serious infections^1,2, but the mechanisms by which pathogens access the brain remain poorly understood. The model microorganism Listeria monocytogenes (Lm) is a major foodborne pathogen that causes neurolisteriosis, one of the deadliest infections of the central nervous system^3,4. Although immunosuppression is a well-established host risk factor for neurolisteriosis^3,5, little is known about the bacterial factors that underlie the neuroinvasion of Lm. Here we develop a clinically relevant experimental model of neurolisteriosis, using hypervirulent neuroinvasive strains⁶ inoculated in a humanized mouse model of infection⁷, and we show that the bacterial surface protein InlB protects infected monocytes from Fas-mediated cell death by CD8⁺ T cells in a manner that depends on c-Met, PI3 kinase and FLIP. This blockade of specific anti-Lm cellular immune killing lengthens the lifespan of infected monocytes, and thereby favours the transfer of Lm from infected monocytes to the brain. The intracellular niche that is created by InlB-mediated cell-autonomous immune resistance also promotes Lm faecal shedding, which accounts for the selection of InlB as a core virulence gene of Lm. We have uncovered a specific mechanism by which a bacterial pathogen confers an increased lifespan to the cells it infects by rendering them resistant to cell-mediated immunity. This promotes the persistence of Lm within the host, its dissemination to the central nervous system and its transmission.

Application of Mesenchymal Stem Cells During Machine Perfusion: An Emerging Novel Strategy for Organ Preservation

Although solid organ transplantation remains the definitive management for patients with end-stage organ failure, this ultimate treatment has been limited by the number of acceptable donor organs. Therefore, efforts have been made to expand the donor pool by utilizing marginal organs from donation after circulatory death or extended criteria donors. However, marginal organs are susceptible to ischemia-reperfusion injury (IRI) and entail higher requirements for organ preservation. Recently, machine perfusion has emerged as a novel preservation strategy for marginal grafts. This technique continually perfuses the organs to mimic the physiologic condition, allows the evaluation of pretransplant graft function, and more excitingly facilitates organ reconditioning during perfusion with pharmacological, gene, and stem cell therapy. As mesenchymal stem cells (MSCs) have anti-oxidative, immunomodulatory, and regenerative properties, mounting studies have demonstrated the therapeutic effects of MSCs on organ IRI and solid organ transplantation. Therefore, MSCs are promising candidates for organ reconditioning during machine perfusion. This review provides an overview of the application of MSCs combined with machine perfusion for lung, kidney, liver, and heart preservation and reconditioning. Promising preclinical results highlight the potential clinical translation of this innovative strategy to improve the quality of marginal grafts.

The Emerging Role of c-Met in Carcinogenesis and Clinical Implications as a Possible Therapeutic Target

Background

c-MET is a receptor tyrosine kinase receptor (RTK) for the hepatocyte growth factor (HGF). The binding of HGF to c-MET regulates several cellular functions: differentiation, proliferation, epithelial cell motility, angiogenesis, and epithelial-mesenchymal transition (EMT). Moreover, it is known to be involved in carcinogenesis. Comprehension of HGF-c-MET signaling pathway might have important clinical consequences allowing to predict prognosis, response to treatment, and survival rates based on its expression and dysregulation. Discussion. c-MET represents a useful molecular target for novel engineered drugs. Several clinical trials are underway for various solid tumors and the development of new specific monoclonal antibodies depends on the recent knowledge about the definite c-MET role in each different malignance. Recent clinical trials based on c-MET molecular targets result in good safety profile and represent a promising therapeutic strategy for solid cancers, in monotherapy or in combination with other target drugs.

Conclusion

The list of cell surface receptors crosslinking with the c-MET signaling is constantly growing, highlighting the importance of this pathway for personalized target therapy. Research on the combination of c-MET inhibitors with other drugs will hopefully lead to discovery of new effective treatment options.

KRAS and MET in non-small-cell lung cancer: two of the new kids on the 'drivers' block

Non-small-cell lung cancer (NSCLC) is a heterogeneous disease, and therapeutic management has advanced to identify various critical oncogenic mutations that promote lung cancer tumorigenesis. Subsequent studies have developed targeted therapies against these oncogenes in the hope of personalized treatment based on the tumor's molecular genomics. This review presents a comprehensive review of the biology, new therapeutic interventions, and resistance patterns of two well-defined subgroups, tumors with KRAS and MET alterations. We also discuss the status of molecular testing practices for these two key oncogenic drivers, considering the progressive introduction of next-generation sequencing (NGS) and RNA sequencing in regular clinical practice.

Gas6 Ameliorates Inflammatory Response and Apoptosis in Bleomycin-Induced Acute Lung Injury

Acute lung injury (ALI) is characterized by alveolar damage, lung edema, and exacerbated inflammatory response. Growth arrest-specific protein 6 (Gas6) mediates many different functions, including cell survival, proliferation, inflammatory signaling, and apoptotic cell clearance (efferocytosis). The role of Gas6 in bleomycin (BLM)-induced ALI is unknown. We investigated whether exogenous administration of mouse recombinant Gas6 (rGas6) has anti-inflammatory and anti-apoptotic effects on BLM-induced ALI. Compared to mice treated with only BLM, the administration of rGas6 reduced the secretion of proinflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, and macrophage inflammatory protein-2, and increased the secretion of hepatocyte growth factor in bronchoalveolar lavage (BAL) fluid. rGas6 administration also reduced BLM-induced inflammation and apoptosis as evidenced by reduced neutrophil recruitment into the lungs, total protein levels in BAL fluid, caspase-3 activity, and TUNEL-positive lung cells in lung tissue. Apoptotic cell clearance by alveolar macrophages was also enhanced in mice treated with both BLM and rGas6 compared with mice treated with only BLM. rGas6 also had pro-resolving and anti-apoptotic effects in mouse bone marrow-derived macrophages and alveolar epithelial cell lines stimulated with BLM in vitro. These findings indicate that rGas6 may play a protective role in BLM-induced ALI.

Antitumor effects of the multi-target tyrosine kinase inhibitor cabozantinib: a comprehensive review of the preclinical evidence

INTRODUCTION

Altered receptor tyrosine kinase (RTK) signaling contributes to tumorigenesis and suppression of immune-mediated destruction of cancer cells. Cabozantinib is an oral tyrosine kinase inhibitor that inhibits several RTKs involved in tumorigenesis, and is approved for the treatment of patients with progressive metastatic medullary thyroid cancer, advanced renal cell carcinoma, and hepatocellular carcinoma that has been previously treated with sorafenib.

AREAS COVERED

We present an up-to-date evaluation of preclinical evidence for RTK inhibition with cabozantinib, specifically VEGFR, MET, KIT, RET, AXL, FLT3, and associated antitumor effects. Preclinical investigations of cabozantinib in combination with other anticancer drugs are also reviewed.

EXPERT OPINION

Preclinical evidence shows that cabozantinib has antitumor activity against various cancer cells and exhibits synergy with other anticancer agents, including immune checkpoint inhibitors and hormone receptor or metabolic pathway inhibitors. Further optimization of cabozantinib treatment requires the identification of biomarkers of response and resistance, and exploration of complementary drug targets. Investigation of mechanisms of adaptive resistance, such as epithelial to mesenchymal transition (cancer intrinsic) and immunomodulation by the tumor microenvironment (cancer extrinsic), as well as identification of novel drug targets based on characterization of cancer stem cell metabolomic phenotypes, appear to be promising approaches.

Extracellular vesicles from in vivo liver tissue accelerate recovery of liver necrosis induced by carbon tetrachloride

Extracellular vesicles (EVs) are nano-sized vesicles composed of proteolipid bilayers carrying various molecular signatures of the cells. As mediators of intercellular communications, EVs have gained great attention as new therapeutic agents in the field of nanomedicine. Therefore, many studies have explored the roles of cell-derived EVs isolated from cultured hepatocytes or stem cells as inducer of liver proliferation and regeneration under various pathological circumstances. However, study investigating the role of EVs directly isolated from liver tissue has not been performed. Herein, to understand the pathophysiological role and to investigate the therapeutic potential of in vivo liver EVs, we isolated EVs from both normal and carbon tetrachloride (CCl4)-induced damaged in vivo liver tissues. The in vivo EVs purified from liver tissues display typical features of EVs including spherical morphology, nano-size, and enrichment of tetraspanins. Interestingly, administration of both normal and damaged liver EVs significantly accelerated the recovery of liver tissue from CCl4-induced hepatic necrosis. This restorative action was through the induction of hepatocyte growth factor at the site of the injury. These results suggest that not only normal liver EVs but also damaged liver EVs play important pathophysiological roles of maintaining homeostasis after tissue damage. Our study, therefore, provides new insight into potentially developing in vivo EV-based therapeutics for preventing and treating liver diseases.

Hepatocyte growth factor regulates HIF-1α-induced nucleus pulposus cell proliferation through MAPK-, PI3K/Akt-, and STAT3-mediated signaling

Intervertebral discs are important for maintaining mobility and offer support to the body trunk. If these discs lose their biomechanical features, lower back pain can occur. We previously reported that hepatocyte growth factor (HGF) promotes cell proliferation and suppresses apoptosis, inflammation, and matrix degradation in nucleus pulposus (NP) cells. In the present study, we investigated the molecular mechanisms of how HGF promotes the proliferation of NP cells in hypoxic conditions. Hypoxic stimulation promoted modest cell proliferation, which was further upregulated by HGF. Expression of hypoxia-inducible factor (HIF-1α) protein, which contributes to the maintenance of homeostasis in NP cells, was also upregulated in hypoxia-treated cell groups; HGF further increased HIF-1α expression in NP cells. Additionally, knockdown of HIF-1α expression significantly reduced the proliferation of NP cells. An MAPK inhibitor inhibited the expression of HIF-1α and pERK, as well as cell proliferation in a dose-dependent manner. Similarly, inhibiting the PI3K/Akt and STAT3 pathways also decreased the expression of HIF-1α and cell proliferation. These results show that under hypoxic conditions, HGF promotes NP cell proliferation via HIF-1α-, MAPK-, PI3K/Akt-, and STAT3-mediated signaling which is involved in this pathway. The control of these signaling pathways may be a target for potential therapeutic strategies for the treatment of disc degeneration in hypoxic conditions.

Molecular mechanisms of esophageal epithelial regeneration following repair of surgical defects with acellular silk fibroin grafts

Constructive remodeling of focal esophageal defects with biodegradable acellular grafts relies on the ability of host progenitor cell populations to repopulate implant regions and facilitate growth of de novo functional tissue. Intrinsic molecular mechanisms governing esophageal repair processes following biomaterial-based, surgical reconstruction is largely unknown. In the present study, we utilized mass spectrometry-based quantitative proteomics and in silico pathway evaluations to identify signaling cascades which were significantly activated during neoepithelial formation in a Sprague Dawley rat model of onlay esophagoplasty with acellular silk fibroin scaffolds. Pharmacologic inhibitor and rescue experiments revealed that epithelialization of neotissues is significantly dependent in part on pro-survival stimuli capable of suppressing caspase activity in epithelial progenitors via activation of hepatocyte growth factor receptor (c-MET), tropomyosin receptor kinase A (TrkA), phosphoinositide 3-kinase (PI3K), and protein kinase B (Akt) signaling mechanisms. These data highlight the molecular machinery involved in esophageal epithelial regeneration following surgical repair with acellular implants.

Anti-apoptotic effect of adipose tissue-derived stromal vascular fraction in denervated rat muscle

BACKGROUND

Recovery of muscle function after peripheral nerve injury is often poor, and this can be attributed to muscle fiber atrophy and cell death. In the current study, we have investigated the effects of stromal vascular fraction (SVF) on muscle cell apoptosis and its potential to preserve muscle tissue following denervation.

METHODS

Rat gastrocnemius muscle was denervated by sciatic nerve transection. At 2 and 4 weeks after injury, muscles were examined histologically and apoptosis was measured using TUNEL assay and PCR array for a range of apoptotic genes. Additionally, an in vitro TNF-α apoptosis model was established using SVF cells co-cultured indirectly with primary rat myoblasts. Annexin V and TUNEL were used together with Western blotting to investigate the signaling pathways.

RESULTS

Denervated muscles showed significantly higher TUNEL reactivity at 2 and 4 weeks following nerve injury, and an increased expression of caspase family genes, mitochondria-related apoptotic genes, and tumor necrosis factor family genes. In cultured rat primary myoblasts, Annexin V labeling was significantly increased at 12 h after TNF-α treatment, and this was followed by a significant increase in TUNEL reactivity at 48 h. Western blotting showed that caspase-7 was activated/cleaved as well as the downstream substrate, poly (ADP-ribose) polymerase (PARP). Co-culture of myoblasts with SVF significantly reduced all these measures of apoptosis. Bax and Bcl-2 levels were not changed suggesting that the TNF-α-induced apoptosis occurred via mitochondria-independent pathways. The protective effect of SVF was also shown in vivo; injections of SVF cells into denervated muscle significantly improved the mean fiber area and diameter, as well as reduced the levels of TUNEL reactivity.

CONCLUSIONS

This study provides new insights into how adipose tissue-derived cells might provide therapeutic benefits by preserving muscle tissue.

Capmatinib for patients with non-small cell lung cancer with MET exon 14 skipping mutations: A review of preclinical and clinical studies

The mesenchymal-epithelial transition (MET) receptor tyrosine kinase binds the hepatocyte growth factor to activate downstream cell signaling pathways involved in cell proliferation, survival, and migration. Several genetic mechanisms can result in an aberrant activation of this receptor in cancer cells. One such activating mechanism involves the acquisition of gene mutations that cause MET exon 14 skipping (METex14) during mRNA splicing. Mutations leading to METex14 are found in approximately 3-4% of patients with non-small cell lung cancer (NSCLC). Accumulating evidence suggests that METex14 is a true, independent oncogenic driver in NSCLC, as well as being an independent prognostic factor for poorer survival in patients with NSCLC. The successes of target therapies have relied on improved understanding of the genetic alterations that lead to the dysregulation of the molecular pathways and more advanced molecular diagnostics. Multiple efforts have been made to target the MET pathway in cancer; however, real clinical progress has only occurred since the emergence of METex14 as a valid biomarker for MET inhibition. Capmatinib is a highly potent and selective type Ib inhibitor of MET. Following preclinical demonstration of activity against MET-dependent cancer cell line growth and MET-driven tumor growth in xenograft models, data from a phase 1 clinical trial showed an acceptable safety profile of capmatinib and preliminary evidence of efficacy in patients with MET-dysregulated NSCLC. The multicohort GEOMETRY mono-1 phase 2 trial reported objective response rates of 68% and 41% in treatment-naïve and in pre-treated patients with METex14 advanced NSCLC, respectively. These results have supported the approval of capmatinib by the US Food and Drug Administration for patients with metastatic NSCLC harboring METex14.

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.

Endothelial HIF-2α as a Key Endogenous Mediator Preventing Emphysema

Rationale: Endothelial injury may provoke emphysema, but molecular pathways of disease development require further discernment. Emphysematous lungs exhibit decreased expression of HIF-2α (hypoxia-inducible factor-2α)-regulated genes, and tobacco smoke decreases pulmonary HIF-2α concentrations. These findings suggest that decreased HIF-2α expression is important in the development of emphysema.Objectives: The objective of this study was to evaluate the roles of endothelial-cell (EC) HIF-2α in the pathogenesis of emphysema in mice.Methods: Mouse lungs were examined for emphysema after either the loss or the overexpression of EC Hif-2α. In addition, SU5416, a VEGFR2 inhibitor, was used to induce emphysema. Lungs were evaluated for HGF (hepatocyte growth factor), a protein involved in alveolar development and homeostasis. Lungs from patients with emphysema were measured for endothelial HIF-2α expression.Measurements and Main Results: EC Hif-2α deletion resulted in emphysema in association with fewer ECs and pericytes. After SU5416 exposure, EC Hif-2α-knockout mice developed more severe emphysema, whereas EC Hif-2α-overexpressing mice were protected. EC Hif-2α-knockout mice demonstrated lower levels of HGF. Human emphysema lung samples exhibited reduced EC HIF-2α expression.Conclusions: Here, we demonstrate a unique protective role for pulmonary endothelial HIF-2α and how decreased expression of this endogenous factor causes emphysema; its pivotal protective function is suggested by its ability to overcome VEGF antagonism. HIF-2α may maintain alveolar architecture by promoting vascular survival and associated HGF production. In summary, HIF-2α may be a key endogenous factor that prevents the development of emphysema, and its upregulation has the potential to foster lung health in at-risk patients.

A review of the processed Polygonum multiflorum (Thunb.) for hepatoprotection: Clinical use, pharmacology and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

Polygonum multiflorum (Thunb.) (PMT) is a member of Polygonaceae. Traditional Chinese medicine considers that the processed PMT can tonify liver, nourish blood and blacken hair. In recent years, the processed PMT and its active ingredients have significant therapeutic effects on nonalcoholic fatty liver disease, alcoholic fatty liver disease, viral hepatitis, liver fibrosis and liver cancer.

AIM OF THE STUDY

The main purpose of this review is to provide a critical appraisal of the existing knowledge on the clinical application, hepatoprotective pharmacology and hepatotoxicity, it provides a comprehensive evaluation of the liver function of the processed PMT.

MATERIALS AND METHODS

A detailed literature search was conducted using various online search engines, such as Pubmed, Google Scholar, Mendeley, Web of Science and China National Knowledge Infrastructure (CNKI) database. The main active components of the processed PMT and the important factors in the occurrence and development of liver diseases are used as key words to carry out detailed literature retrieval.

RESULTS

In animal and cell models, the processed PMT and active components can treat various liver diseases, such as fatty liver induced by high-fat diet, liver injury and fibrosis induced by drugs, viral transfected hepatitis, hepatocellular carcinoma, etc. They can protect liver by regulating lipid metabolism related enzymes, resisting insulin resistance, decreasing the expression of inflammatory cytokines, inhibiting the activation of hepatic stellate cells, reducing generation of extracellular matrix, promoting cancer cell apoptosis and controlling the growth of tumor cells, etc. However, improperly using of the processed PMT can cause liver injury, which is associated with the standardization of processing, the constitution of the patients, the characteristics of the disease, and the administration of dosage and time.

CONCLUSION

The processed PMT can treat various liver diseases via reasonably using, and the active compounds (2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside, emodin, physcion, etc.) are promising candidate drugs for developing new liver protective agents. However, some components have a "toxic-effective" bidirectional effect, which should be used cautiously.

HGF-MET Signaling Shifts M1 Macrophages Toward an M2-Like Phenotype Through PI3K-Mediated Induction of Arginase-1 Expression

Backgrounds and Aims: Hepatocyte Growth Factor (HGF)-MET signaling is known to promote biological functions such as cell survival, cell motility, and cell proliferation. However, it is unknown if HGF-MET alters the macrophage phenotype. In this study, we aimed to study the effects of HGF-MET signaling on the M1 macrophage phenotype.

Methods and Materials: Bone marrow-derived macrophages (BMDMs) isolated from mice were either polarized to an M1 phenotype by IFN-γ and LPS treatment or to an M2 phenotype by IL-4 treatment. Changes in M1 or M2 markers induced by HGF-MET signaling were evaluated. Mechanisms responsible for alternations in the macrophage phenotype and intracellular metabolism were analyzed.

Results: c-Met was expressed especially in M1 macrophages polarized by treatment with IFN-γ and LPS. In M1 macrophages, HGF-MET signaling induced the expression of Arg-1 mRNA and secretion of IL-10 and TGF-β1 and downregulated the mRNA expression of iNOS, TNF-α, and IL-6. In addition, activation of the PI3K pathway and inactivation of NFκB were also observed in M1 macrophages treated with HGF. The increased Arg-1 expression and IL-10 secretion were abrogated by PI3K inhibition, whereas, no changes were observed in TNF-α and IL-6 expression. The inactivation of NFκB was found to be independent of the PI3K pathway. HGF-MET signaling shifted the M1 macrophages to an M2-like phenotype, mainly through PI3K-mediated induction of Arg-1 expression. Finally, HGF-MET signaling also shifted the M1 macrophage intracellular metabolism toward an M2 phenotype, especially with respect to fatty acid metabolism.

Conclusion: Our results suggested that HGF treatment not only promotes regeneration in epithelial cells, but also leads to tissue repair by altering M1 macrophages to an M2-like phenotype.

The AKT-independent MET-V-ATPase-MTOR axis suppresses liver cancer vaccination

Despite recent progress in hepatitis treatment, there have been no significant advances in the development of liver cancer vaccines in recent years. In this study, we investigated the regulatory effect and potential mechanism of hepatocyte growth factor receptor (MET, also known as HGFR) on tumor vaccinations for liver cancer in mice. Herein, we demonstrate that MET expression is significantly associated with the immunogenicity of liver cancer in mice and humans, and that MET depletion dramatically enhances the protective efficacy of chemotherapy-based anti-liver cancer vaccination. Mechanistically, MET repressed liver cancer immunogenicity independent of the traditional PI3K–AKT cascade, and MET interacted with vacuolar ATP synthase (V-ATPase) and mediated the activation of mammalian target of rapamycin (MTOR), thus suppressing liver cancer immunogenicity. The efficacy of chemotherapy-based liver cancer vaccination was markedly enhanced by targeting the MET–V-ATPase–MTOR axis, highlighting a translational strategy for identifying MET-associated drug candidates for cancer prevention.

A PI3K- and GTPase-independent Rac1-mTOR mechanism mediates MET-driven anchorage-independent cell growth but not migration

Receptor tyrosine kinases (RTKs) are often overexpressed or mutated in cancers and drive tumor growth and metastasis. In the current model of RTK signaling, including that of MET, downstream phosphatidylinositol 3-kinase (PI3K) mediates both cell proliferation and cell migration, whereas the small guanosine triphosphatase (GTPase) Rac1 mediates cell migration. However, in cultured NIH3T3 and glioblastoma cells, we found that class I PI3K mediated oncogenic MET-induced cell migration but not anchorage-independent growth. In contrast, Rac1 regulated both processes in distinct ways. Downstream of PI3K, Rac1 mediated cell migration through its GTPase activity, whereas independently of PI3K, Rac1 mediated anchorage-independent growth in a GTPase-independent manner through an adaptor function. Through its RKR motif, Rac1 formed a complex with the kinase mTOR to promote its translocation to the plasma membrane, where its activity promoted anchorage-independent growth of the cell cultures. Inhibiting mTOR with rapamycin suppressed the growth of subcutaneous MET-mutant cell grafts in mice, including that of MET inhibitor-resistant cells. These findings reveal a GTPase-independent role for Rac1 in mediating a PI3K-independent MET-to-mTOR pathway and suggest alternative or combined strategies that might overcome resistance to RTK inhibitors in patients with cancer.

Normothermic machine perfusion of donor-lungs ex-vivo: promoting clinical adoption

PURPOSE OF REVIEW

Lung transplantation offers the only realistic therapeutic option for patients with end-stage lung disease. However, this is impacted by a shortfall in availability of suitable donor-lungs. Normothermic machine perfusion of donor-lungs outside the donor body also known as ex-vivo lung perfusion (EVLP) offers a potential solution through objective assessment, reconditioning and treatment of donor-lungs initially deemed unsuitable for use. This review discusses key advances and challenges in the wider clinical adoption of this technology.

RECENT FINDINGS

This review will summarize key research within the following areas: recent clinical trials utilizing EVLP, logistical challenges, EVLP protocol innovations, novel assessment methods and current research into therapeutic modulation of lung function during EVLP.

SUMMARY

Normothermic machine perfusion of donor-lungs ex-vivo offers a promising platform to assess and modulate donor-lung quality prior to transplantation. Consensus on how and when to best utilize EVLP is yet to be reached, meaning that widespread clinical adoption of the technology has not yet become a reality. Further work is needed on agreed indications, perfusion protocols and organization of services before becoming a regularly used procedure prior to lung transplantation.

Molecular Engineering Strategies Tailoring the Apoptotic Response to a MET Therapeutic Antibody

The MET oncogene encodes a tyrosine kinase receptor involved in the control of a complex network of biological responses that include protection from apoptosis and stimulation of cell growth during embryogenesis, tissue regeneration, and cancer progression. We previously developed an antagonist antibody (DN30) inducing the physical removal of the receptor from the cell surface and resulting in suppression of the biological responses to MET. In its bivalent form, the antibody displayed a residual agonist activity, due to dimerization of the lingering receptors, and partial activation of the downstream signaling cascade. The balance between the two opposing activities is variable in different biological systems and is hardly predictable. In this study, we generated and characterized two single-chain antibody fragments derived from DN30, sharing the same variable regions but including linkers different in length and composition. The two engineered molecules bind MET with high affinity but induce different biological responses. One behaves as a MET-antagonist, promoting programmed cell death in MET “addicted” cancer cells. The other acts as a hepatocyte growth factor (HGF)-mimetic, protecting normal cells from doxorubicin-induced apoptosis. Thus, by engineering the same receptor antibody, it is possible to generate molecules enhancing or inhibiting apoptosis either to kill cancer cells or to protect healthy tissues from the injuries of chemotherapy.

MET targeting: time for a rematch

MET, the receptor tyrosine kinase (RTK) for hepatocyte growth factor, is a proto-oncogene involved in embryonic development and throughout life in homeostasis and tissue regeneration. Deregulation of MET signaling has been reported in numerous malignancies, prompting great interest in MET targeting for cancer therapy. The present review offers a summary of the biology of MET and its known functions in normal physiology and carcinogenesis, followed by an overview of the most relevant MET-targeting strategies and corresponding clinical trials, highlighting both past setbacks and promising future prospects. By placing their efforts on a more precise stratification strategy through the genetic analysis of tumors, modern trials such as the NCI-MATCH trial could revive the past enthusiasm for MET-targeted therapy.

Thiosemicarbazones suppress expression of the c-Met oncogene by mechanisms involving lysosomal degradation and intracellular shedding

Considering the role of proto-oncogene c-Met (c-Met) in oncogenesis, we examined the effects of the metastasis suppressor, N-myc downstream-regulated gene-1 (NDRG1), and two NDRG1-inducing thiosemicarbazone-based agents, Dp44mT and DpC, on c-Met expression in DU145 and Huh7 cells. NDRG1 silencing without Dp44mT and DpC up-regulated c-Met expression, demonstrating that NDRG1 modulates c-Met levels. Dp44mT and DpC up-regulated NDRG1 by an iron-dependent mechanism and decreased c-Met levels, c-Met phosphorylation, and phosphorylation of its downstream effector, GRB2-associated binding protein 1 (GAB1). However, incubation with Dp44mT and DpC after NDRG1 silencing or silencing of the receptor tyrosine kinase inhibitor, mitogen-inducible gene 6 (MIG6), decreased c-Met and its phosphorylation, suggesting NDRG1- and MIG6-independent mechanism(s). Lysosomal inhibitors rescued the Dp44mT- and DpC-mediated c-Met down-regulation in DU145 cells. Confocal microscopy revealed that lysosomotropic agents and the thiosemicarbazones significantly increased co-localization between c-Met and lysosomal-associated membrane protein 2 (LAMP2). Moreover, generation of c-Met C-terminal fragment (CTF) and its intracellular domain (ICD) suggested metalloprotease-mediated cleavage. In fact, Dp44mT increased c-Met CTF while decreasing the ICD. Dp44mT and a γ-secretase inhibitor increased cellular c-Met CTF levels, suggesting that Dp44mT induces c-Met CTF levels by increasing metalloprotease activity. The broad metalloprotease inhibitors, EDTA and batimastat, partially prevented Dp44mT-mediated down-regulation of c-Met. In contrast, the ADAM inhibitor, TIMP metallopeptidase inhibitor 3 (TIMP-3), had no such effect, suggesting c-Met cleavage by another metalloprotease. Notably, Dp44mT did not induce extracellular c-Met shedding that could decrease c-Met levels. In summary, the thiosemicarbazones Dp44mT and DpC effectively inhibit oncogenic c-Met through lysosomal degradation and metalloprotease-mediated cleavage.

In a Rat Model of Acute Liver Failure, Icaritin Improved the Therapeutic Effect of Mesenchymal Stem Cells by Activation of the Hepatocyte Growth Factor/c-Met Pathway

Acute liver failure (ALF) is a serious life-threatening condition. Mesenchymal stem cells (MSCs) may be an effective treatment for this condition and a good alternative to liver transplantation. Icaritin (ICT) is an active ingredient of the genus Epimedium, a traditional Chinese medicine, with the potential to enhance the proliferation of MSCs. The purpose of this study was to explore whether ICT increased the therapeutic effects of MSCs and explore its underlying mechanisms. For in vivo experiments, a rat ALF model was established by intraperitoneal injection of D(+)-galactosamine/ lipopolysaccharide. MSCs cocultured with ICT were used to treat ALF rats and the protective effects assessed as survival rate, levels of serum AST and ALT, and histological changes in liver tissue. For in vitro experiments, MSCs were treated in serum-free culture for 72 h to simulate the disruption of intrahepatic microcirculation. MSCs apoptosis was examined to determine whether ICT rescued impaired MSCs. The role of the hepatocyte growth factor (HGF)/c-Met pathway in MSCs was assessed by constructing genetically modified MSCs overexpressing c-Met and by using the c-Met receptor inhibitor (crizotinib). The results showed that MSCs increased the survival rate of ALF rats and reduced liver damage. MSCs cocultured with ICT exerted a greater therapeutic effect than MSCs alone. Further, the HGF/c-Met pathway played a key role in the antiapoptotic activity of MSCs, which was associated with the optimized efficacy of ICT. In conclusion, this study demonstrated that ICT enhances the therapeutic effect of MSCs in a model of ALF, improving the antiapoptotic potential of MSCs by upregulation of the HGF/c-Met pathway. The combination of stem cell therapy with traditional herbal extracts may improve MSC-based clinical applications.

Licochalcone B inhibits growth and induces apoptosis of human non-small-cell lung cancer cells by dual targeting of EGFR and MET

BACKGROUND

Epidermal growth factor receptor (EGFR) gene alterations are associated with sensitization to tyrosine kinase inhibitors such as gefitinib in lung cancer. Some patients suffering from non-small cell lung cancer (NSCLC) have difficulty in treating the cancer due to resistance acquired to gefitinib with MET amplification. Therefore EGFR and MET may be attractive targets for lung cancer therapy.

PURPOSE

This study aimed to investigate the anti-cancer activity of Licochalcone (LC)B extracted from Glycyrrhiza inflata, in gefitinib-sensitive or gefitinib-resistant NSCLC cells, and to define its mechanisms.

STUDY DESIGN

We investigated the mechanism of action of LCB by targeting EGFR and MET in human NSCLC cells.

METHODS

We used the HCC827 and HCC827GR lines as gefitinib-sensitive and -resistant cells respectively, and determined the effects of LCB on both, by performing cell proliferation assay, flow cytometry analysis and Western blotting. Targets of LCB were identified by pull-down/kinase assay and molecular docking simulation.

RESULTS

LCB inhibited both EGFR and MET kinase activity by directly binding to their ATP-binding pockets. The ability of this interaction was verified by computational docking and molecular dynamics simulations. LCB suppressed viability and colony formation of both HCC827 and HCC827GR cells while exhibiting no cytotoxicity to normal cells. The induction of G2/M cell-cycle arrest and apoptosis by LCB was confirmed by Annexin V/7-AAD double staining, ER stress and reactive oxygen species induction, mitochondrial membrane potential loss and caspase activation as well as related-proteins regulation. Inhibition of EGFR and MET by LCB decreased ERBB3 and AKT axis activation.

CONCLUSION

We provide insights into the LCB-mediated mechanisms involved in reducing cell proliferation and inducing apoptosis in NSCLC cells. This occurs through dual inhibition of EGFR and MET in NSCLC cells regardless of their sensitivity or resistance to gefitinib. LCB may be a promising novel therapeutic medicine for gefitinib-sensitive or resistant NSCLC treatment.

Current perspectives of cancer-associated fibroblast in therapeutic resistance: potential mechanism and future strategy

The goal of cancer eradication has been overshadowed despite the continuous improvement in research and generation of novel cancer therapeutic drugs. One of the undeniable existing problems is drug resistance due to which the paradigm of killing all cancer cells is ineffective. Tumor microenvironment plays a crucial role in inducing drug resistance besides cancer development and progression. Recently, many efforts have been devoted to understand the role of tumor microenvironment in cancer drug resistance as it provides the shelter, nutrition, and paracrine niche for cancer cells. Cancer-associated fibroblasts (CAFs), one major component of tumor microenvironment, reside in symbiotic relationship with cancer cells, supporting them to survive from cancer drugs. The present review summarizes the recent understandings in the role of CAFs in drug resistance in various tumors. Acknowledging the fact that drug resistance depends not only upon cancer cells but also upon the microenvironment niche could guide us to formulate novel cancer drugs and provide the optimal cancer treatment.

PI3K/AKT inhibitors aggravate death receptor-mediated hepatocyte apoptosis and liver injury

The PI3K/AKT signaling pathway is one of the most frequently activated signaling networks in human cancers and has become a valuable target in anticancer therapy. However, accumulating reports suggest that adverse effects such as severe liver injury and inflammation may accompany treatment with pan-PI3K and pan-AKT inhibitors. Our prior work has demonstrated that activation of the PI3K/AKT pathway has a protective role in Fas- or TNFα-induced hepatocytic cell death and liver injury. We postulated that PI3K or AKT inhibitors may exacerbate liver damage via the death factor-mediated hepatocyte apoptosis. In this study we found that several drugs targeting PI3K/AKT either clinically used or in clinical trials sensitized hepatocytes to agonistic anti-Fas antibody- or TNFα-induced apoptosis and significantly shortened the survival of mice in in vivo liver damage models. The PI3K or AKT inhibitors promoted Fas aggregation, inhibited the expression of cellular FLICE-inhibitory protein S and L (FLIP_L/S), and enhanced procaspase-8 activation. Conversely, cotreatment with the AKT specific activator SC79 reversed these effects. Taken together, these findings suggest that PI3K or AKT inhibitors may render hepatocytes hypersensitive to Fas- or TNFα-induced apoptosis and liver injury.

A Novel AKT Activator, SC79, Prevents Acute Hepatic Failure Induced by Fas-Mediated Apoptosis of Hepatocytes

Acute liver failure is a serious clinical problem of which the underlying pathogenesis remains unclear and for which effective therapies are lacking. The Fas receptor/ligand system, which is negatively regulated by AKT, is known to play a prominent role in hepatocytic cell death. We hypothesized that AKT activation may represent a strategy to alleviate Fas-induced fulminant liver failure. We report here that a novel AKT activator, SC79, protects hepatocytes from apoptosis induced by agonistic anti-Fas antibody CH11 (for humans) or Jo2 (for mice) and significantly prolongs the survival of mice given a lethal dose of Jo2. Under Fas-signaling stimulation, SC79 inhibited Fas aggregation, prevented the recruitment of the adaptor molecule Fas-associated death domain (FADD) and procaspase-8 [or FADD-like IL-1β-converting enzyme (FLICE)] into the death-inducing signaling complex (DISC), but SC79 enhanced the recruitment of the long and short isoforms of cellular FLICE-inhibitory protein at the DISC. All of the SC79-induced hepatoprotective and DISC-interruptive effects were confirmed to have been reversed by the Akt inhibitor LY294002. These results strongly indicate that SC79 protects hepatocytes from Fas-induced fatal hepatic apoptosis. The potent alleviation of Fas-mediated hepatotoxicity by the relatively safe drug SC79 highlights the potential of our findings for immediate hepatoprotective translation.

Significantly enhanced recovery of acute liver failure by liver targeted delivery of stem cells via heparin functionalization

Acute liver failure (ALF) occurs by insufficient detoxification of toxic materials in the liver, generating excess reactive oxygen species (ROS). Mesenchymal stem cell (MSC) therapy can be a promising approach for the treatment of liver diseases including ALF by anti-inflammatory activity and secretion of cytokines associated with tissue regeneration. However, the efficacy of MSC therapy is generally poor, mainly due to a low survival and engraftment of administered cells. In this study, we demonstrated that the enhanced delivery of human adipose-derived stem cells (hADSCs) to the damaged liver by the coating of lipid-conjugated heparin could result in significantly improved recovery from ALF in a mouse model. First, the therapeutic effect of secretomes of hADSCs on acetaminophen (APAP)-induced hepatic cell damage was confirmed regardless of the coating of lipid-conjugated heparin on hADSCs in vitro. Then, the therapeutic effects of lipid-conjugated heparin coated hADSCs (Lip-Hep/hADSC group) were analyzed compared to hADSCs themselves (hADSC group) using an APAP-induced ALF model in vivo. Intravenous administration of hADSCs could lower the elevated serum levels of aspartate transaminase (AST) and alanine transaminase (ALT), but Lip-Hep/hADSC group showed faster decrease in serum levels of AST and ALT to the normal values compared to hADSC group. Enhanced delivery and longer retention of hADSCs in the damage liver by the coating of lipid-conjugated heparin were confirmed by optical imaging of isolated organs using labeled cells and immunofluorescence staining of liver tissue sections against human nuclei. A significantly increased level of human hepatic growth factor (hHGF), a representative secretome from hADSC, significantly reduced levels of macrophage and CYP2E1, implying alleviated inflammatory response, were detected by immunofluorescence staining from Lip-Hep/hADSC group compared to hADSC group. These results well coincided with the improved recovery of the damaged liver from Lip-Hep/hADSC group than hADSC group in histological analysis. Thus, the coating of lipid-conjugated heparin on hADSCs has a great potential to improve the therapeutic effect of cells on the liver injury.

Hepatoprotective Activity of InlB321/15, the HGFR Ligand of Bacterial Origin, in CCI4-Induced Acute Liver Injury Mice

HGF (hepatocyte growth factor)/HGFR (HGF receptor) signaling pathway is a key pathway in liver protection and regeneration after acute toxic damage. Listeria monocytogenes toxin InlB contains a HGFR-interacting domain and is a functional analog of HGF. The aim of this work was to evaluate the hepatoprotective activity of the InlB HGFR-interacting domain. The recombinant HGFR-interacting domain InlB321/15 was purified from E. coli. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test was used to measure InlB321/15 mitogenic activity in HepG2 cells. Activation of MAPK- and PI3K/Akt-pathways was tracked with fluorescent microscopy, Western blotting, and ELISA. To evaluate hepatoprotective activity, InlB321/15 and recombinant human HGF (rhHGF) were intravenously injected at the same concentration of 2 ng·g⁻¹ to BALB/c mice 2 h before liver injury with CCl₄. InlB321/15 caused dose-dependent activation of MAPK- and PI3K/Akt-pathways and correspondent mitogenic effects. Both InlB321/15 and rhHGF improved macroscopic liver parameters (liver mass was 1.51, 1.27 and 1.15 g for the vehicle, InlB321/15 and rhHGF, respectively, p < 0.05), reduced necrosis (24.0%, 16.18% and 21.66% of the total area for the vehicle, InlB321/15 and rhHGF, respectively, p < 0.05). Obtained data suggest that InlB321/15 is a promising candidate for a tissue repair agent.

Novel agent #2714 potently inhibits lung cancer growth by suppressing cell proliferation and by inducing apoptosis in vitro and in vivo

The use of small molecule compounds to inhibit cell proliferation is one of the most promising approaches in cancer therapy. In the present study, a cell viability assay, flow cytometry analysis, western blotting and mouse xenograft models were used to investigate the anticancer activities of #2714 and its underlying mechanisms in lung cancer. The present in vitro results suggested that #2714 significantly inhibited the viability of the human non-small cell lung cancer line SPC-A1 in a concentration- and time-dependent manner, with a half-maximal inhibitory concentration value of 5.54 µM after 48 h of treatment. Additionally, #2714 inhibited SPC-A1 cell proliferation via the Wnt/β-catenin pathway and by impairing mitochondrial membrane potential. The protein expression levels of Wnt 3a, Wnt 5a/b, phosphorylated (p)-β-catenin, p-glycogen synthase kinase 3β, and p-mitogen-activated protein kinase 14 were downregulated following treatment with #2714. Furthermore, using a mouse xenograft model, #2714 was identified to significantly inhibit tumor growth and to decrease cancer cell proliferation in vivo. #2714 may represent a novel effective anticancer compound targeting lung cancer cells. Additionally, #2714 was able to induce apoptosis and decrease cell proliferation in SPC-A1 cells via the Wnt/β-catenin pathway.

AKT activator SC79 protects hepatocytes from TNF-α-mediated apoptosis and alleviates d-Gal/LPS-induced liver injury

Tumor necrosis factor-α (TNF-α) is a highly pleiotropic cytokine executing biological functions as diverse as cell proliferation, metabolic activation, inflammatory responses, and cell death. TNF-α can induce multiple mechanisms to initiate apoptosis in hepatocytes leading to the subsequent liver injury. Since the phosphoinositide-3-kinase/protein kinase B (PI3K/Akt) pathway is known to have a protective role in death factor-mediated apoptosis, it is our hypothesis that activation of Akt may represent a therapeutic strategy to alleviate TNF-α-induced hepatocyte apoptosis and liver injury. We report here that the Akt activator SC79 protects hepatocytes from TNF-α-induced apoptosis and protects mice from d-galactosamine (d-Gal)/lipopolysaccharide (LPS)-induced TNF-α-mediated liver injury and damage. SC79 not only enhances the nuclear factor-κB (NF-κB) prosurvival signaling in response to TNF-α stimulation, but also increases the expression of cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein L and S (FLIP_L/S), which consequently inhibits the activation of procaspase-8. Furthermore, pretreatment of the PI3K/Akt inhibitor LY294002 reverses all the SC79-induced hepatoprotective effects. These results strongly indicate that SC79 protects against TNF-α-induced hepatocyte apoptosis and suggests that SC79 is likely a promising therapeutic agent for ameliorating the development of liver injury. NEW & NOTEWORTHY SC79 protects hepatocytes from TNF-α-mediated apoptosis and mice from Gal/LPS-induced liver injury and damage. Cytoprotective effects of SC79 against TNF-α act through both AKT-mediated activation of NF-κB and upregulation of FLIP_L/S.

Salidroside-Pretreated Mesenchymal Stem Cells Enhance Diabetic Wound Healing by Promoting Paracrine Function and Survival of Mesenchymal Stem Cells Under Hyperglycemia

Systemic abnormalities cause several complications in diabetes patients. Impaired wound healing is a serious complication that leads to severe foot ulcer and amputation. Mesenchymal stem cells (MSCs) have been considered a promising strategy for promoting wound healing due to their paracrine function. However, their poor survival after transplantation limits their therapeutic effect and applications. Salidroside, a glucopyranoside, has been reported to exert cytoprotective effects. Our previous study revealed that salidroside could promote the paracrine function of skeletal muscle cells. However, whether salidroside could improve MSCs survival under hyperglycemic condition and, subsequently, promote wound healing in diabetic model mice remains unknown. Here, we found that salidroside pretreatment effectively reversed the hyperglycemia-induced suppression of the expression of crucial wound healing factors in MSCs, such as heme oxygenase-1 (HO-1), fibroblast growth factor 2 (FGF2), and hepatocyte growth factor (HGF). Salidroside pretreatment also suppressed the hyperglycemia-induced intracellular reactive oxygen species (ROS) levels in MSCs, thereby lowering the apoptosis rate and enhancing MSCs survival rate. Furthermore, salidroside improved the MSCs migration potential that was impaired under hyperglycemia. in vivo experiments revealed that salidroside pretreatment prior to transplantation significantly enhanced the effect of MSCs in promoting wound closure in diabetic mice. Collectively, our results suggest that pretreatment with salidroside could be an effective strategy to enhance the survival rate and the therapeutic effect of MSCs. Thus, our article suggested a novel, potential MSC-based strategy for diabetic wound healing. Stem Cells Translational Medicine 2019;8:404-414.