Scatter factor is a fibroblast-derived modulator of epithelial cell mobility

Extrusion of BMP2+ surface colonocytes promotes stromal remodeling and tissue regeneration

The colon epithelium frequently incurs damage through toxic influences. Repair is rapid, mediated by cellular plasticity and acquisition of the highly proliferative regenerative state. However, the mechanisms that promote the regenerative state are not well understood. Here, we reveal that upon injury and subsequent inflammatory response, IFN-γ drives widespread epithelial remodeling. IFN-γ promotes rapid apoptotic extrusion of fully differentiated surface colonocytes, while simultaneously causing differentiation of crypt-base stem and progenitor cells towards a colonocyte-like lineage. However, unlike homeostatic colonocytes, these IFN-γ-induced colonocytes neither respond to nor produce BMP-2 but retain regenerative capacity. The reduction of BMP-2-producing epithelial surface cells causes a remodeling of the surrounding mesenchymal niche, inducing high expression of HGF, which promotes proliferation of the IFN-γ-induced colonocytes. This mechanism of lineage replacement and subsequent remodeling of the mesenchymal niche enables tissue-wide adaptation to injury and efficient repair.

Angiogenesis: Biological Mechanisms and In Vitro Models

The translation of biomedical devices and drug research is an expensive and long process with a low probability of receiving FDA approval. Developing physiologically relevant in vitro models with human cells offers a solution to not only improving the odds of FDA approval but also to expand our ability to study complex in vivo systems in a simpler fashion. Animal models remain the standard for pre-clinical testing; however, the data from animal models is an unreliable extrapolation when anticipating a human response in clinical trials, thus contributing to the low rates of translation. In this review, we focus on in vitro vascular or angiogenic models because of the incremental role that the vascular system plays in the translation of biomedical research. The first section of this review discusses the most common angiogenic cytokines that are used in vitro to initiate angiogenesis, followed by angiogenic inhibitors where both initiators and inhibitors work to maintain vascular homeostasis. Next, we evaluate previously published in vitro models, where we evaluate capturing the physical environment for biomimetic in vitro modeling. These topics provide a foundation of parameters that must be considered to improve and achieve vascular biomimicry. Finally, we summarize these topics to suggest a path forward with the goal of engineering human in vitro models that emulate the in vivo environment and provide a platform for biomedical device and drug screening that produces data to support clinical translation.

Hepatic Growth Factor as a Potential Biomarker for Lung Adenocarcinoma: A Multimodal Study

(1) Background: Despite previous studies linking inflammatory cytokines to lung adenocarcinoma (LUAD), their causal mechanisms remain unclear. This study aims to explore the causal relationship between inflammatory cytokines and LUAD to fill this knowledge gap. (2) Methods: This study employs a comprehensive approach, integrating Mendelian randomization (MR) analysis, single-cell RNA sequencing (scRNA-seq), and transcriptomic sequencing (RNA-seq) data to investigate the relationship between inflammatory cytokines and LUAD. (3) Results: In forward MR analysis, elevated levels of hepatocyte growth factor (HGF), interleukin-1 receptor antagonist (IL-1RA), IL-5, monocyte chemoattractant protein-3, and monokine induced by interferon-γ were causally associated with an increased risk of LUAD. In reverse MR analysis, LUAD exhibited a positive causal relationship with the levels of regulated upon activation normal T cell expressed and secreted factor (RANTES) and stromal cell-derived factor-1α. The scRNA-seq data further identified specific cell populations that may influence LUAD onset and progression through the expression of particular inflammatory genes and intercellular communication. RNA-seq data analysis highlighted the role of the HGF gene in LUAD diagnosis, demonstrating its strong correlation with patient prognosis and immune cell infiltration within the tumor microenvironment. (4) Conclusions: The findings reveal a causal relationship between inflammatory cytokines and LUAD, with HGF emerging as a potential biomarker of significant clinical relevance. This study provides new insights into the molecular mechanisms underlying LUAD and lays the foundation for future therapeutic strategies.

Bioactive Products Targeting C-Met As Potential Antitumour Drugs

Mesenchymal‒epithelial transition factor (c-Met), a receptortyrosine kinase (RTK), plays a vital role in cell proliferation, migration and invasion, and tumour metastasis.

OBJECTIVE

With increasing duration of treatment, many tumours gradually develop drug resistance. Therefore, novel antitumour drugs need to be developed to treat patients with tumours. Targeting c-met inhibitors may be an effective treatment strategy.

METHODS

Scientific databases such as ScienceDirect, PubMed, the Wiley Online Library, and Social Sciences Citation Index were used to collect information. All the relevant literature was reviewed, and the available literature was screened. The upstream and downstream pathways of c-Met and their relevance to antitumour effects were searched based on the articles' title, abstract, and full text. The c-Met-targeting drugs with antitumour effects are summarized below. A "citation within a citation" or snowballing approach was used in this screening process to identify additional papers that may have been missed in the initial literature screening process. High-quality studies published in peer-reviewed journals were summarized and prioritized for citation in the review.

RESULTS

In recent years, research on small-molecule targeted drugs has developed rapidly. Many results have also been achieved in the synthesis and isolation of c-Met inhibitors from natural compounds and traditional Chinese medicines.

CONCLUSION

This article summarizes the developments in anti-c-Met drugs, which are synthesized and isolated from natural compounds and traditional Chinese medicine (TCM). This study provides primary resources for the development of c-Met inhibitors.

Ocular surface squamous neoplasia: Update on genetics, epigenetics and opportunities for targeted therapy

PURPOSE

The purpose of this review is to explore the molecular foundations of ocular surface squamous neoplasia (OSSN), focusing on the genetic and epigenetic aspects. While current management strategies include surgical excision and medical therapies, the understanding of OSSN's molecular basis remains limited, hindering the development of targeted treatments.

METHODS

A comprehensive MEDLINE search was conducted for literature published between January 1993 and October 2023. Only studies with original data on molecular, genetic, or epigenetic mechanisms, such as mutations, gene expression, and genetic predispositions were included. Articles were excluded if they focused solely on clinical management without addressing these factors, or if they were reviews, editorials, or opinion pieces.

RESULTS

The search yielded a total of 108 articles, out of which 39 articles met the criteria for further analysis. Investigations into OSSN have identified key DNA mutations in the TP53, HGF, EGFR, TERT, and CDKN2A genes, indicating common oncogenic pathways shared with other squamous cell carcinomas (SCCs). Significant epigenetic changes were identified, including DNA methylation, histone modifications, and altered miRNA expression patterns. Epigenetic dysregulation of critical tumor suppressors and oncoproteins, further highlight the complex genetic landscape of OSSN.

CONCLUSION

The molecular alterations identified in OSSN not only enhance our understanding of its biology but also have potential as novel biomarkers for early detection, prognostic evaluation, and as therapeutic targets. The identification of genetic and epigenetic markers in OSSN signifies progress towards personalized medicine approaches. Further studies and collaborative efforts are essential to validate these molecular markers and translate them into clinical practice, potentially revolutionizing OSSN management and improving patient outcomes.

Transcriptomic analysis of the 12 major human breast cell types reveals mechanisms of cell and tissue function

A fundamental question in biology, central to our understanding of cancer and other pathologies, is determining how different cell types coordinate to form and maintain tissues. Recognizing the distinct features and capabilities of the cells that compose these tissues is critical. Unfortunately, the complexity of tissues often hinders our ability to distinguish between neighboring cell types and, in turn, scrutinize their transcriptomes and generate reliable and tractable cell models for studying their inherently different biologies. We have recently introduced a novel method that permits the identification and purification of the 12 cell types that compose the human breast-nearly all of which could be reliably propagated in the laboratory. Here, we explore the nature of these cell types. We sequence mRNAs from each purified population and investigate transcriptional patterns that reveal their distinguishing features. We describe the differentially expressed genes and enriched biological pathways that capture the essence of each cell type, and we highlight transcripts that display intriguing expression patterns. These data, analytic tools, and transcriptional analyses form a rich resource whose exploration provides remarkable insights into the inner workings of the cell types composing the breast, thus furthering our understanding of the rules governing normal cell and tissue function.

Cancer Metastases to the Liver: Mechanisms of Tumor Cell Colonization

The liver is one of the most common sites for metastasis, which involves the spread from primary tumors to surrounding organs and tissues in the human body. There are a few steps in cancer expansion: invasion, inflammatory processes allowing the hepatic niche to be created, adhesions to ECM, neovascularization, and secretion of enzymes. The spread of tumor cells depends on the microenvironment created by the contribution of many biomolecules, including proteolytic enzymes, cytokines, growth factors, and cell adhesion molecules that enable tumor cells to interact with the microenvironment. Moreover, the microenvironment plays a significant role in tumor growth and expansion. The secreted enzymes help cancer cells facilitate newly formed hepatic niches and promote migration and invasion. Our study discusses pharmacological methods used to prevent liver metastasis by targeting the tumor microenvironment and cancer cell colonization in the liver. We examine randomized studies focusing on median survival duration and median overall survival in patients administered placebo compared with those treated with bevacizumab, ramucirumab, regorafenib, and ziv-aflibercept in addition to current chemotherapy. We also include research on mice and their responses to these medications, which may suppress metastasis progression. Finally, we discuss the significance of non-pharmacological methods, including surgical procedures, radiotherapy, cryotherapy, radiofrequency ablation (RFA), and transarterial embolization (TAE). In conclusion, the given methods can successfully prevent metastases to the liver and prolong the median survival duration and median overall survival in patients suffering from cancer.

Selected aspects of avascular tumor growth reproduced by a hybrid model of cell dynamics and chemical kinetics

We here propose a hybrid computational framework to reproduce and analyze aspects of the avascular progression of a generic solid tumor. Our method first employs an individual-based approach to represent the population of tumor cells, which are distinguished in viable and necrotic agents. The active part of the disease is in turn differentiated according to a set of metabolic states. We then describe the spatio-temporal evolution of the concentration of oxygen and of tumor-secreted proteolytic enzymes using partial differential equations (PDEs). A differential equation finally governs the local degradation of the extracellular matrix (ECM) by the malignant mass. Numerical realizations of the model are run to reproduce tumor growth and invasion in a number scenarios that differ for cell properties (adhesiveness, duplication potential, proteolytic activity) and/or environmental conditions (level of tissue oxygenation and matrix density pattern). In particular, our simulations suggest that tumor aggressiveness, in terms of invasive depth and extension of necrotic tissue, can be reduced by (i) stable cell-cell contact interactions, (ii) poor tendency of malignant agents to chemotactically move upon oxygen gradients, and (iii) presence of an overdense matrix, if coupled by a disrupted proteolytic activity of the disease.

Profile of Capmatinib for the Treatment of Metastatic Non-Small Cell Lung Cancer (NSCLC): Patient Selection and Perspectives

Aberrant c-MET (Mesenchymal-Epithelial Transition) signaling contributes to cancer cell development, proliferation, and metastases of non-small cell lung cancer (NSCLC). MET exon 14 (METex14) skipping mutation is noted in approximately 4% of NSCLC cases and is targetable with the recently approved tyrosine kinase inhibitors capmatinib and tepotinib. Capmatinib, the focus of this review article, is a highly selective MET inhibitor approved for use in patients with METex14 mutated NSCLC. In this review, we discuss cMET as a target, the pharmacology of capmatinib, key trials of capmatinib in MET-altered lung cancer, and toxicity profile. We highlight some ongoing capmatinib clinical trials that expand their role to other subsets of patients, especially those with EGFR mutations, who develop MET alterations as a resistance pathway. We further provide our perspective on the management of METex14 NSCLC, strategies for sequencing agents, and toxicity management.

MET exon 14 skipping mutation is a hepatocyte growth factor (HGF)-dependent oncogenic driver in vitro and in humanised HGF knock-in mice

Exon skipping mutations of the MET receptor tyrosine kinase (METex14), increasingly reported in cancers, occur in 3-4% of non-small-cell lung cancer (NSCLC). Only 50% of patients have a beneficial response to treatment with MET-tyrosine kinase inhibitors (TKIs), underlying the need to understand the mechanism of METex14 oncogenicity and sensitivity to TKIs. Whether METex14 is a driver mutation and whether it requires hepatocyte growth factor (HGF) for its oncogenicity in a range of in vitro functions and in vivo has not been fully elucidated from previous preclinical models. Using CRISPR/Cas9, we developed a METex14/WT isogenic model in nontransformed human lung cells and report that the METex14 single alteration was sufficient to drive MET-dependent in vitro anchorage-independent survival and motility and in vivo tumorigenesis, sensitising tumours to MET-TKIs. However, we also show that human HGF (hHGF) is required, as demonstrated in vivo using a humanised HGF knock-in strain of mice and further detected in tumour cells of METex14 NSCLC patient samples. Our results also suggest that METex14 oncogenicity is not a consequence of an escape from degradation in our cell model. Thus, we developed a valuable model for preclinical studies and present results that have potential clinical implication.

Increased collective migration correlates with germline stem cell competition in a basal chordate

Cell competition is a process that compares the relative fitness of progenitor cells, resulting in winners, which contribute further to development, and losers, which are excluded, and is likely a universal quality control process that contributes to the fitness of an individual. Cell competition also has pathological consequences, and can create super-competitor cells responsible for tumor progression. We are studying cell competition during germline regeneration in the colonial ascidian, Botryllus schlosseri. Germline regeneration is due to the presence of germline stem cells (GSCs) which have a unique property: a competitive phenotype. When GSCs from one individual are transplanted into another, the donor and recipient cells compete for germline development. Often the donor GSCs win, and completely replace the gametes of the recipient- a process called germ cell parasitism (gcp). gcp is a heritable trait, and winner and loser genotypes can be found in nature and reared in the lab. However, the molecular and cellular mechanisms underlying gcp are unknown. Using an ex vivo migration assay, we show that GSCs isolated from winner genotypes migrate faster and in larger clusters than losers, and that cluster size correlates with expression of the Notch ligand, Jagged. Both cluster size and jagged expression can be manipulated simultaneously in a genotype dependent manner: treatment of loser GSCs with hepatocyte growth factor increases both jagged expression and cluster size, while inhibitors of the MAPK pathway decrease jagged expression and cluster size in winner GSCs. Live imaging in individuals transplanted with labeled winner and loser GSCs reveal that they migrate to the niche, some as small clusters, with the winners having a slight advantage in niche occupancy. Together, this suggests that the basis of GSC competition resides in a combination in homing ability and niche occupancy, and may be controlled by differential utilization of the Notch pathway.

HGF/c-Met/β1-integrin signalling axis induces tunneling nanotubes in A549 lung adenocarcinoma cells

Tunneling nanotubes (TNTs) are thin cytoplasmic extensions involved in long-distance intercellular communication and can transport intracellular organelles and signalling molecules. In cancer cells, TNT formation contributes to cell survival, chemoresistance, and malignancy. However, the molecular mechanisms underlying TNT formation are not well defined, especially in different cancers. TNTs are present in non-small cell lung cancer (NSCLC) patients with adenocarcinoma. In NSCLC, hepatocyte growth factor (HGF) and its receptor, c-Met, are mutationally upregulated, causing increased cancer cell growth, survival, and invasion. This study identifies c-Met, β1-integrin, and paxillin as novel components of TNTs in A549 lung adenocarcinoma cells, with paxillin localised at the protrusion site of TNTs. The HGF-induced TNTs in our study demonstrate the ability to transport lipid vesicles and mitochondria. HGF-induced TNT formation is mediated by c-Met and β1-integrin in conjunction with paxillin, followed by downstream activation of MAPK and PI3K pathways and the Arp2/3 complex. These findings demonstrate a potential novel approach to inhibit TNT formation through targeting HGF/c-Met receptor and β1-integrin signalling interactions, which has implications for multi-drug targeting in NSCLC.

MET in Non-Small-Cell Lung Cancer (NSCLC): Cross 'a Long and Winding Road' Looking for a Target

Non-Small-Cell Lung Cancer (NSCLC) can harbour different MET alterations, such as MET overexpression (MET OE), MET gene amplification (MET AMP), or MET gene mutations. Retrospective studies of surgical series of patients with MET-dysregulated NSCLC have shown worse clinical outcomes irrespective of the type of specific MET gene alteration. On the other hand, earlier attempts failed to identify the 'druggable' molecular gene driver until the discovery of MET exon 14 skipping mutations (METex14). METex14 are rare and amount to around 3% of all NSCLCs. Patients with METex14 NSCLC attain modest results when they are treated with immune checkpoint inhibitors (ICIs). New selective MET inhibitors (MET-Is) showed a long-lasting clinical benefit in patients with METex14 NSCLC and modest activity in patients with MET AMP NSCLC. Ongoing clinical trials are investigating new small molecule tyrosine kinase inhibitors, bispecific antibodies, or antibodies drug conjugate (ADCs). This review focuses on the prognostic role of MET, the summary of pivotal clinical trials of selective MET-Is with a focus on resistance mechanisms. The last section is addressed to future developments and challenges.

In vitro differentiated human CD4+ T cells produce hepatocyte growth factor

Differentiation of naive CD4⁺ T cells into effector T cells is a dynamic process in which the cells are polarized into T helper (Th) subsets. The subsets largely consist of four fundamental categories: Th1, Th2, Th17, and regulatory T cells. We show that human memory CD4⁺ T cells can produce hepatocyte growth factor (HGF), a pleiotropic cytokine which can affect several tissue types through signaling by its receptor, c-Met. In vitro differentiation of T cells into Th-like subsets revealed that HGF producing T cells increase under Th1 conditions. Enrichment of HGF producing cells was possible by targeting cells with surface CD30 expression, a marker discovered through single-cell RNA-sequencing. Furthermore, pharmacological inhibition of PI3K or mTOR was found to inhibit HGF mRNA and protein, while an Akt inhibitor was found to increase these levels. The findings suggest that HGF producing T cells could play a role in disease where Th1 are present.

Hepatocyte growth factor combined with adenosine deaminase as biomarker for diagnosis of tuberculous pleural effusion

Background

The simple, rapid, and accurate diagnosis of tuberculous pleural effusion (TPE) remains difficult. This study aimed to determine the accuracy of hepatocyte growth factor (HGF) in the diagnosis of TPE.

Methods

We quantified the expression of HGF, adenosine deaminase (ADA), and interferon gamma (IFN-γ) in pleural effusion (PE) in 97 TPE subjects and 116 non-TPE subjects using an enzyme-linked immunosorbent assay (ELISA) or a fully automatic biochemical analyzer. The diagnostic performance of these three biomarkers was evaluated using a receiver operating characteristic (ROC) curve of subjects by age and gender.

Results

We discovered that the TPE group had much higher levels of HGF than the non-TPE group, regardless of age or gender, and that there was no statistically significant difference between the two groups' levels of HGF expression in peripheral plasma. In female TPE patients aged ≤65 years, the AUCs of TPE and non-TPE diagnosed by HGF, ADA or IFN-γ were 0.988, 0.964, and 0.827, respectively. HGF plus ADA had the highest diagnostic efficacy in female TPE patients aged ≤65 years. With HGF plus ADA having a cut-off value of 0.219 for distinguishing TPE from non-TPE, the area under the curve (AUC), sensitivity (SEN), specificity (SPE), positive predictive value (PPV), and negative predictive value (NPV) were, respectively, 0.998 (95% confidence interval [CI], 0.993-1.000), 100 (95% CI, 89.997-100.000), 96.667 (95% CI, 82.783-99.916), 97.222 (95% CI, 83.594-99.586), and 100.

Conclusion

This study confirmed that HGF plus ADA has high diagnostic efficacy in younger female TPE patients and has the potential to be an excellent biomarker.

Heterogeneous Expression of PD-L1, B7x, B7-H3, and HHLA2 in Pulmonary Sarcomatoid Carcinoma and the Related Regulatory Signaling Pathways

Immunotherapy has transformed lung cancer management, but PSC remains an aggressive subtype with a poor prognosis. This study investigates the differential expression of PD-L1 and alternative immune checkpoints (ICs; B7x, B7-H3, and HHLA2), and genetic alterations in PSCs. Tumor specimens of 41 PSC patients were evaluated. PD-L1, B7x, B7-H3, and HHLA2 were positive in 75.0%, 67.6%, 73.0%, and 91.9% of tumors, respectively. PD-L1 expression was significantly higher in the epithelial compared to the sarcomatoid component (median TPS: 50% vs. 0%, p = 0.010). Expression of PD-L1 in both components was only seen in 32.1% of patients. However, at least one IC was expressed in 92.9% of epithelial and 100% of sarcomatoid components. Furthermore, METex14 was detected in 19.5% of patients and was associated with a higher sarcomatoid percentage. Our preclinical studies revealed that METex14 induced PD-L1 expression via MAPK or PI3K/Akt pathways, and MET inhibitors decreased PD-L1 expression. Our findings demonstrate distinct expressions of ICs in PSC subcomponents. Thus, combination IC inhibition as a therapeutic strategy in PSC warrants further exploration. A high percentage of METex14 in PSC and its role in regulating PD-L1 expression reveal different therapeutic targets in this aggressive NSCLC subtype.

Growth factors and their peptide mimetics for treatment of traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of disability in adults, caused by a physical insult damaging the brain. Growth factor-based therapies have the potential to reduce the effects of secondary injury and improve outcomes by providing neuroprotection against glutamate excitotoxicity, oxidative damage, hypoxia, and ischemia, as well as promoting neurite outgrowth and the formation of new blood vessels. Despite promising evidence in preclinical studies, few neurotrophic factors have been tested in clinical trials for TBI. Translation to the clinic is not trivial and is limited by the short in vivo half-life of the protein, the inability to cross the blood-brain barrier and human delivery systems. Synthetic peptide mimetics have the potential to be used in place of recombinant growth factors, activating the same downstream signalling pathways, with a decrease in size and more favourable pharmacokinetic properties. In this review, we will discuss growth factors with the potential to modulate damage caused by secondary injury mechanisms following a traumatic brain injury that have been trialled in other indications including spinal cord injury, stroke and neurodegenerative diseases. Peptide mimetics of nerve growth factor (NGF), hepatocyte growth factor (HGF), glial cell line-derived growth factor (GDNF), brain-derived neurotrophic factor (BDNF), platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) will be highlighted, most of which have not yet been tested in preclinical or clinical models of TBI.

A novel PLS1 c.981+1G>A variant causes autosomal-dominant hereditary hearing loss in a family

The fimbrin protein family contains a variety of proteins, among which Plastin1 (PLS1) is an important member. According to recent studies, variations in the coding region of the PLS1 gene are associated with the development of deafness. However, the molecular mechanism of deafness caused by PLS1 gene variants remains unknown. Whole-exome sequencing was performed on hearing-impaired family members and hearing family members to identify pathogenic variants, followed by Sanger sequencing. A minigene assay was conducted to investigate the effect of the variant on PLS1 mRNA splicing. The pathogenicity of the variant was further investigated in zebrafish. RNA-sequencing (RNA-seq) was performed to analyze the dysregulation of downstream signaling pathways caused by knockdown of PLS1 expression. We identified a novel variant, PLS1 c.981+1G>A, in a large Chinese family with hearing loss and showed that the variant is responsible for the occurrence of hearing loss by inducing exon 8 skipping. The variant caused abnormal inner ear phenotypes, characterized by decreases in the mean otolith distance, anterior otolith diameter, posterior otolith diameter, cochlear diameter, and swimming speed and distance in zebrafish. Furthermore, silencing PLS1 expression significantly upregulated the expression of genes in the PI3K-Akt signaling pathway, including Col6a3, Spp1, Itgb3 and hepatocyte growth factor (Hgf). PLS1 c.981+1G>A is a novel pathogenic variant causing hearing loss by inducing exon 8 skipping. Upregulation of the expression of genes in the PI3K-Akt signaling pathway plays an important role in the pathogenesis caused by variants in the PLS1 gene.

Landscape of Savolitinib Development for the Treatment of Non-Small Cell Lung Cancer with MET Alteration-A Narrative Review

Non-small cell lung cancer (NSCLC) is increasingly being treated with targeted therapies. Savolitinib (Orpathys^®) is highly selective mesenchymal epithelial transition (MET)-tyrosine kinase inhibitor (TKI), which is conditionally approved in China for advanced NSCLC with MET exon 14 skipping mutations (METex14). This article summarizes the clinical development of savolitinib, as a monotherapy in NSCLC with METex14 mutation and in combination with epidermal growth factor receptor (EGFR) inhibitor in post EGFR-TKI resistance NSCLC due to MET-based acquired resistance. Preclinical models demonstrated anti-tumor activities in MET-driven cancer cell line and xenograft tumor models. The Phase Ia/Ib study established an optimized, recommended phase II dose in Chinese NSCLC patients, while TATTON study of savolitinib plus osimertinib in patients with EGFR mutant, MET-amplified and TKI-progressed NSCLC showed beneficial efficacy with acceptable safety profile. In a pivotal phase II study, Chinese patients with pulmonary sarcomatoid carcinoma, brain metastasis and other NSCLC subtype positive for METex14 mutation showed notable responses and acceptable safety profile with savolitinib. Currently, results from ongoing clinical trials are eagerly anticipated to confirm the efficacious and safety benefits of savolitinib as monotherapy and in combination with EGFR-TKI in acquired resistance setting in advanced NSCLC and its subtypes with MET alterations.

Dimerization of kringle 1 domain from hepatocyte growth factor/scatter factor provides a potent MET receptor agonist

We designed and characterized a potent full MET receptor agonist consisting of two recombinantly linked HGF/SF kringle 1 domains and demonstrated its potential in epithelial tissue regeneration.

Hepatocyte growth factor/scatter factor (HGF/SF) and its cognate receptor MET play several essential roles in embryogenesis and regeneration in postnatal life of epithelial organs such as the liver, kidney, lung, and pancreas, prompting a strong interest in harnessing HGF/SF-MET signalling for regeneration of epithelial organs after acute or chronic damage. The limited stability and tissue diffusion of native HGF/SF, however, which reflect the tightly controlled, local mechanism of action of the morphogen, have led to a major search of HGF/SF mimics for therapy. In this work, we describe the rational design, production, and characterization of K1K1, a novel minimal MET agonist consisting of two copies of the kringle 1 domain of HGF/SF in tandem orientation. K1K1 is highly stable and displays biological activities equivalent or superior to native HGF/SF in a variety of in vitro assay systems and in a mouse model of liver disease. These data suggest that this engineered ligand may find wide applications in acute and chronic diseases of the liver and other epithelial organs dependent of MET activation.

A feedback loop between lamellipodial extension and HGF-ERK signaling specifies leader cells during collective cell migration

Upon the initiation of collective cell migration, the cells at the free edge are specified as leader cells; however, the mechanism underlying the leader cell specification remains elusive. Here, we show that lamellipodial extension after the release from mechanical confinement causes sustained extracellular signal-regulated kinase (ERK) activation and underlies the leader cell specification. Live-imaging of Madin-Darby canine kidney (MDCK) cells and mouse epidermis through the use of Förster resonance energy transfer (FRET)-based biosensors showed that leader cells exhibit sustained ERK activation in a hepatocyte growth factor (HGF)-dependent manner. Meanwhile, follower cells exhibit oscillatory ERK activation waves in an epidermal growth factor (EGF) signaling-dependent manner. Lamellipodial extension at the free edge increases the cellular sensitivity to HGF. The HGF-dependent ERK activation, in turn, promotes lamellipodial extension, thereby forming a positive feedback loop between cell extension and ERK activation and specifying the cells at the free edge as the leader cells. Our findings show that the integration of physical and biochemical cues underlies the leader cell specification during collective cell migration.

Fibroblasts mediate the angiogenesis of pheochromocytoma by increasing COX4I2 expression

Objective

Our previous work found COX4I2 was associated with angiogenesis in pheochromocytoma. The purpose of this study was to explore the role of COX4I2 in regulating angiogenesis in pheochromocytoma.

Methods

Distribution of COX4I2 was evaluated by scRNA-seq in one case of pheochromocytoma and the findings were verified by immunostaining. COX4I2 was further knocked down in target cells. Changes of angiogenesis-related genes were evaluated by qPCR in target cells.

Results

The scRNA-seq revealed high mRNA expression of COX4I2 in fibroblasts rather than tumor cells. Immunostaining of COX4I2 confirmed its distribution in fibroblasts. Knocking down COX4I2 in NIH3T3 cell line led to significant reduction of angiogenesis-related genes, especially ANG1 and HGF.

Conclusions

Fibroblasts mediate the angiogenesis of pheochromocytoma by increasing COX4I2 expression, possibly by affecting ANG1 and HGF.

c-Met Signaling as a Therapeutic Target in Head and Neck Cancer

ABSTRACT

Despite a dearth of activating driver mutations in head and neck squamous cell carcinoma (HNSCC), aberrant activation of the oncogenes, epidermal growth factor receptor (EGFR), and c-Met is near-universal in human papillomavirus (HPV)-negative disease. Although EGFR activation drove the successful development of the anti-EGFR monoclonal antibody cetuximab in HNSCC, no c-Met-targeting therapy has gained regulatory approval. Inhibition of the c-Met pathway may subvert oncogenesis within the tumor-intrinsic compartment, blocking tumoral proliferation, invasion, migration, and metastasis, or the tumor-extrinsic compartment, modulating the immunosuppressive tumor microenvironment. This review discusses the rationale and current drug development strategies for targeting c-Met or its exclusive ligand hepatocyte growth factor (HGF) in HNSCC.

Epithelial–mesenchymal transition: The history, regulatory mechanism, and cancer therapeutic opportunities

Epithelial–mesenchymal transition (EMT) is a program wherein epithelial cells lose their junctions and polarity while acquiring mesenchymal properties and invasive ability. Originally defined as an embryogenesis event, EMT has been recognized as a crucial process in tumor progression. During EMT, cell–cell junctions and cell–matrix attachments are disrupted, and the cytoskeleton is remodeled to enhance mobility of cells. This transition of phenotype is largely driven by a group of key transcription factors, typically Snail, Twist, and ZEB, through epigenetic repression of epithelial markers, transcriptional activation of matrix metalloproteinases, and reorganization of cytoskeleton. Mechanistically, EMT is orchestrated by multiple pathways, especially those involved in embryogenesis such as TGFβ, Wnt, Hedgehog, and Hippo, suggesting EMT as an intrinsic link between embryonic development and cancer progression. In addition, redox signaling has also emerged as critical EMT modulator. EMT confers cancer cells with increased metastatic potential and drug resistant capacity, which accounts for tumor recurrence in most clinic cases. Thus, targeting EMT can be a therapeutic option providing a chance of cure for cancer patients. Here, we introduce a brief history of EMT and summarize recent advances in understanding EMT mechanisms, as well as highlighting the therapeutic opportunities by targeting EMT in cancer treatment.

Fibroadipogenic Progenitors Regulate the Basal Proliferation of Satellite Cells and Homeostasis of Pharyngeal Muscles via HGF Secretion

Skeletal muscle stem cells, known as satellite cells (SCs), are quiescent in normal adult limb muscles. Injury stimulates SC proliferation, differentiation, and fusion to regenerate muscle structure. In pharyngeal muscles, which are critical for swallowing foods and liquids, SCs proliferate and fuse in the absence of injury. It is unknown what factors drive increased basal activity of pharyngeal SCs. Here, we determined how niche factors influence the status of pharyngeal versus limb SCs. In vivo, a subset of pharyngeal SCs present features of activated SCs, including large cell size and increased mitochondrial content. In this study, we discovered that the pharyngeal muscle contains high levels of active hepatocyte growth factor (HGF), which is known to activate SCs in mice and humans. We found that fibroadipogenic progenitors (FAPs) are the major cell type providing HGF and are thus responsible for basal proliferation of SCs in pharyngeal muscles. Lastly, we confirmed the critical role of FAPs for pharyngeal muscle function and maintenance. This study gives new insights to explain the distinctive SC activity of pharyngeal muscles.

Therapeutic Strategies for Ovarian Cancer in Point of HGF/c-MET Targeting

Ovarian cancer is the fifth leading cause of cancer deaths in women and is regarded as one of the most difficult cancers to treat. Currently, studies are being conducted to develop therapeutic agents for effective treatment of ovarian cancer. In this review, we explain the properties of the hepatocyte growth factor (HGF)/mesenchymal-epithelial transition factor (c-MET) and how the signaling pathway of HGF/c-MET is activated in different cancers and involved in tumorigenesis and metastasis of ovarian cancer. We present the findings of clinical studies using small chemicals or antibodies targeting HGF/c-MET signaling in various cancer types, particularly in ovarian cancer. We also discuss that HGF/c-MET-targeted therapy, when combined with chemo drugs, could be an effective strategy for ovarian cancer therapeutics.

Intrinsic Differences in Spatiotemporal Organization and Stromal Cell Interactions Between Isogenic Lung Cancer Cells of Epithelial and Mesenchymal Phenotypes Revealed by High-Dimensional Single-Cell Analysis of Heterotypic 3D Spheroid Models

The lack of inadequate preclinical models remains a limitation for cancer drug development and is a primary contributor to anti-cancer drug failures in clinical trials. Heterotypic multicellular spheroids are three-dimensional (3D) spherical structures generated by self-assembly from aggregates of two or more cell types. Compared to traditional monolayer cell culture models, the organization of cells into a 3D tissue-like structure favors relevant physiological conditions with chemical and physical gradients as well as cell-cell and cell-extracellular matrix (ECM) interactions that recapitulate many of the hallmarks of cancer in situ. Epidermal growth factor receptor (EGFR) mutations are prevalent in non-small cell lung cancer (NSCLC), yet various mechanisms of acquired resistance, including epithelial-to-mesenchymal transition (EMT), limit the clinical benefit of EGFR tyrosine kinase inhibitors (EGFRi). Improved preclinical models that incorporate the complexity induced by epithelial-to-mesenchymal plasticity (EMP) are urgently needed to advance new therapeutics for clinical NSCLC management. This study was designed to provide a thorough characterization of multicellular spheroids of isogenic cancer cells of various phenotypes and demonstrate proof-of-principle for the applicability of the presented spheroid model to evaluate the impact of cancer cell phenotype in drug screening experiments through high-dimensional and spatially resolved imaging mass cytometry (IMC) analyses. First, we developed and characterized 3D homotypic and heterotypic spheroid models comprising EGFRi-sensitive or EGFRi-resistant NSCLC cells. We observed that the degree of EMT correlated with the spheroid generation efficiency in monocultures. In-depth characterization of the multicellular heterotypic spheroids using immunohistochemistry and high-dimensional single-cell analyses by IMC revealed intrinsic differences between epithelial and mesenchymal-like cancer cells with respect to self-sorting, spatiotemporal organization, and stromal cell interactions when co-cultured with fibroblasts. While the carcinoma cells harboring an epithelial phenotype self-organized into a barrier sheet surrounding the fibroblasts, mesenchymal-like carcinoma cells localized to the central hypoxic and collagen-rich areas of the compact heterotypic spheroids. Further, deep-learning-based single-cell segmentation of IMC images and application of dimensionality reduction algorithms allowed a detailed visualization and multiparametric analysis of marker expression across the different cell subsets. We observed a high level of heterogeneity in the expression of EMT markers in both the carcinoma cell populations and the fibroblasts. Our study supports further application of these models in pre-clinical drug testing combined with complementary high-dimensional single-cell analyses, which in turn can advance our understanding of the impact of cancer-stroma interactions and epithelial phenotypic plasticity on innate and acquired therapy resistance in NSCLC.

HGF/c-Met: A Key Promoter in Liver Regeneration

Hepatocyte growth factor (HGF) is a peptide-containing multifunctional cytokine that acts on various epithelial cells to regulate cell growth, movement and morphogenesis, and tissue regeneration of injured organs. HGF is sequestered by heparin-like protein in its inactive form and is widespread in the extracellular matrix of most tissues. When the liver loses its average mass, volume, or physiological and biochemical functions due to various reasons, HGF binds to its specific receptor c-Met (cellular mesenchymal-epithelial transition) and transmits the signals into the cells, and triggers the intrinsic kinase activity of c-Met. The downstream cascades of HGF/c-Met include JAK/STAT3, PI3K/Akt/NF-κB, and Ras/Raf pathways, affecting cell proliferation, growth, and survival. HGF has important clinical significance for liver fibrosis, hepatocyte regeneration after inflammation, and liver regeneration after transplantation. And the development of HGF as a biological drug for regenerative therapy of diseases, that is, using recombinant human HGF protein to treat disorders in clinical trials, is underway. This review summarizes the recent findings of the HGF/c-Met signaling functions in liver regeneration.

Discovery of small-molecule fluorescent probes for C-Met

C-mesenchymal-epithelia transition factor (c-Met) is highly expressed in various solid tumors such as gastric cancer, liver cancer, and lung cancer, playing a pivotal role in the growth, maintenance, and development of different tumor cells. In this study, three small-molecule fluorescent probes (5, 11, 16) targeting c-Met were developed, and their design strategies were also initially explored. In general, the fluorescence properties of the probes themselves could meet the imaging requirements, and they have shown sufficient inhibitory activities against c-Met, especially probe 16, reflecting the targeting and acceptance. Also, fluorescence polarization assays and flow cytometry analysis verified the binding between the probes and c-Met. Cell imaging confirmed that these probes could be used to label c-Met on living cells. It is of positive significance for the development of c-Met kinase inhibitors and tumor pathology research.

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.

The hepatocyte growth factor/mesenchymal epithelial transition factor axis in high-risk pediatric solid tumors and the anti-tumor activity of targeted therapeutic agents

Clinical trials completed in the last two decades have contributed significantly to the improved overall survival of children with cancer. In spite of these advancements, disease relapse still remains a significant cause of death in this patient population. Often, increasing the intensity of current protocols is not feasible because of cumulative toxicity and development of drug resistance. Therefore, the identification and clinical validation of novel targets in high-risk and refractory childhood malignancies are essential to develop effective new generation treatment protocols. A number of recent studies have shown that the hepatocyte growth factor (HGF) and its receptor Mesenchymal epithelial transition factor (c-MET) influence the growth, survival, angiogenesis, and metastasis of cancer cells. Therefore, the c-MET receptor tyrosine kinase and HGF have been identified as potential targets for cancer therapeutics and recent years have seen a race to synthesize molecules to block their expression and function. In this review we aim to summarize the literature that explores the potential and biological rationale for targeting the HGF/c-MET pathway in common and high-risk pediatric solid tumors. We also discuss selected recent and ongoing clinical trials with these agents in relapsed pediatric tumors that may provide applicable future treatments for these patients.

c-Met-integrin cooperation: Mechanisms, tumorigenic effects, and therapeutic relevance

c-Met is a receptor tyrosine kinase which upon activation by its ligand, the hepatocyte growth factor, mediates many important signalling pathways that regulate cellular functions such as survival, proliferation, and migration. Its oncogenic and tumorigenic signalling mechanisms, greatly contributing to cancer development and progression, are well documented. Integrins, heterogeneous adhesion receptors which facilitate cell-extracellular matrix interactions, are important in biomechanically sensitive cell adhesion and motility but also modulate diverse cell behaviour. Here we review the studies which reported cooperation between c-Met and several integrins, particularly β1 and β4, in various cell models including many tumour cell types. From the various experimental models and results analysed, we propose that c-Met-integrin cooperation occurs via inside-out or outside-in signalling. Thus, either c-Met activation triggers integrin activation and cell adhesion or integrin adhesion to its extracellular ligand triggers c-Met activation. These two modes of cooperation require the adhesive function of integrins and mostly lead to cell migration and invasion. In a third, less conventional, mode of cooperation, the integrin plays the role of a signalling adaptor for c-Met, independently from its adhesive property, leading to anchorage independent survival. Recent studies have revealed the influence of endocytic trafficking in c-Met-integrin cooperation including the adaptor function of integrin occurring on endomembranes, triggering an inside-in signalling, believed to promote survival of metastatic cells. We present the evidence of the cooperation in vivo and in human tissues and highlight its therapeutic relevance. A better understanding of the mechanisms regulating c-Met-integrin cooperation in cancer progression could lead to the design of new therapies targeting this cooperation, providing more effective therapeutic approaches than c-Met or integrin inhibitors as monotherapies used in the clinic.

Engineering, Characterization, and Biological Evaluation of an Antibody Targeting the HGF Receptor

The Hepatocyte growth factor (HGF) and its receptor (MET) promote several physiological activities such as tissue regeneration and protection from cell injury of epithelial, endothelial, neuronal and muscle cells. The therapeutic potential of MET activation has been scrutinized in the treatment of acute tissue injury, chronic inflammation, such as renal fibrosis and multiple sclerosis (MS), cardiovascular and neurodegenerative diseases. On the other hand, the HGF-MET signaling pathway may be caught by cancer cells and turned to work for invasion, metastasis, and drug resistance in the tumor microenvironment. Here, we engineered a recombinant antibody (RDO24) and two derived fragments, binding the extracellular domain (ECD) of the MET protein. The antibody binds with high affinity (8 nM) to MET ECD and does not cross-react with the closely related receptors RON nor with Semaphorin 4D. Deletion mapping studies and computational modeling show that RDO24 binds to the structure bent on the Plexin-Semaphorin-Integrin (PSI) domain, implicating the PSI domain in its binding to MET. The intact RDO24 antibody and the bivalent Fab2, but not the monovalent Fab induce MET auto-phosphorylation, mimicking the mechanism of action of HGF that activates the receptor by dimerization. Accordingly, the bivalent recombinant molecules induce HGF biological responses, such as cell migration and wound healing, behaving as MET agonists of therapeutic interest in regenerative medicine. In vivo administration of RDO24 in the murine model of MS, represented by experimental autoimmune encephalomyelitis (EAE), delays the EAE onset, mitigates the early clinical symptoms, and reduces inflammatory infiltrates. Altogether, these results suggest that engineered RDO24 antibody may be beneficial in multiple sclerosis and possibly other types of inflammatory disorders.

Roles of MET in human cancer

The MET proto-oncogene was first identified in osteosarcoma cells exposed to carcinogens. Although expressed in many normal cells, MET is overexpressed in many human cancers. MET is involved in the initiation and development of various human cancers and mediates proliferation, migration and invasion. Accordingly, MET has been successfully used as a biomarker for diagnosis and prognosis, survival, post-operative recurrence, risk assessment and pathologic grading, as well as a therapeutic target. In addition, recent work indicates that inhibition of MET expression and function has potential clinical benefit. This review summarizes the role, mechanism, and clinical significance of MET in the formation and development of human cancer.

Understanding the Role of Fibroblasts following a 3D Tumoroid Implantation for Breast Tumor Formation

An understanding of the participation and modulation of fibroblasts during tumor formation and growth is still unclear. Among many speculates, one might be the technical challenge to reveal the versatile function of fibroblasts in tissue complexity, and another is the dynamics in tissue physiology and cell activity. The histology of most solid tumors shows a predominant presence of fibroblasts, suggesting that tumor cells recruit fibroblasts for breast tumor growth. In this review paper, therefore, the migration, activation, differentiation, secretion, and signaling systems that are associated with fibroblasts and cancer-associated fibroblasts (CAFs) after implantation of a breast tumoroid, i.e., a lab-generated tumor tissue into an animal, are discussed.

Cytoplasmic pressure maintains epithelial integrity and inhibits cell motility

Cytoplasmic pressure, a function of actomyosin contractility and water flow, can regulate cellular morphology and dynamics. In mesenchymal cells, cytoplasmic pressure powers cell protrusion through physiological three-dimensional extracellular matrices. However, the role of intracellular pressure in epithelial cells is relatively unclear. Here we find that high cytoplasmic pressure is necessary to maintain barrier function, one of the hallmarks of epithelial homeostasis. Further, our data show that decreased cytoplasmic pressure facilitates lamellipodia formation during the epithelial to mesenchymal transition (EMT). Critically, activation of the actin nucleating protein Arp2/3 is required for the reduction in cytoplasmic pressure and lamellipodia formation in response to treatment with hepatocyte growth factor (HGF) to induce EMT. Thus, elevated cytoplasmic pressure functions to maintain epithelial tissue integrity, while reduced cytoplasmic pressure triggers lamellipodia formation and motility during HGF-dependent EMT.

HGF/c-MET pathway in cancer: from molecular characterization to clinical evidence

This review provides a comprehensive landscape of HGF/c-MET (hepatocyte growth factor (HGF) /mesenchymal-epithelial transition factor (c-MET)) signaling pathway in cancers. First, we generalize the compelling influence of HGF/c-MET pathway on multiple cellular processes. Then, we present the genomic characterization of HGF/c-MET pathway in carcinogenesis. Furthermore, we extensively illustrate the malignant biological behaviors of HGF/c-MET pathway in cancers, in which hyperactive HGF/c-MET signaling is considered as a hallmark. In addition, we investigate the current clinical trials of HGF/c-MET-targeted therapy in cancers. We find that although HGF/c-MET-targeted therapy has led to breakthroughs in certain cancers, monotherapy of targeting HGF/c-MET has failed to demonstrate significant clinical efficacy in most cancers. With the advantage of the combinations of HGF/c-MET-targeted therapy, the exploration of more options of combinational targeted therapy in cancers may be the major challenge in the future.

HGF and MET: From Brain Development to Neurological Disorders

Hepatocyte growth factor (HGF) and its tyrosine kinase receptor, encoded by the MET cellular proto-oncogene, are expressed in the nervous system from pre-natal development to adult life, where they are involved in neuronal growth and survival. In this review, we highlight, beyond the neurotrophic action, novel roles of HGF-MET in synaptogenesis during post-natal brain development and the connection between deregulation of MET expression and developmental disorders such as autism spectrum disorder (ASD). On the pharmacology side, HGF-induced MET activation exerts beneficial neuroprotective effects also in adulthood, specifically in neurodegenerative disease, and in preclinical models of cerebral ischemia, spinal cord injuries, and neurological pathologies, such as Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). HGF is a key factor preventing neuronal death and promoting survival through pro-angiogenic, anti-inflammatory, and immune-modulatory mechanisms. Recent evidence suggests that HGF acts on neural stem cells to enhance neuroregeneration. The possible therapeutic application of HGF and HGF mimetics for the treatment of neurological disorders is discussed.

State of the structure address on MET receptor activation by HGF

The MET receptor tyrosine kinase (RTK) and its cognate ligand hepatocyte growth factor (HGF) comprise a signaling axis essential for development, wound healing and tissue homeostasis. Aberrant HGF/MET signaling is a driver of many cancers and contributes to drug resistance to several approved therapeutics targeting other RTKs, making MET itself an important drug target. In RTKs, homeostatic receptor signaling is dependent on autoinhibition in the absence of ligand binding and orchestrated set of conformational changes induced by ligand-mediated receptor dimerization that result in activation of the intracellular kinase domains. A fundamental understanding of these mechanisms in the MET receptor remains incomplete, despite decades of research. This is due in part to the complex structure of the HGF ligand, which remains unknown in its full-length form, and a lack of high-resolution structures of the complete MET extracellular portion in an apo or ligand-bound state. A current view of HGF-dependent MET activation has evolved from biochemical and structural studies of HGF and MET fragments and here we review what these findings have thus far revealed.

The epithelial-mesenchymal transition and the cytoskeleton in bioengineered systems

The epithelial-mesenchymal transition (EMT) is intrinsically linked to alterations of the intracellular cytoskeleton and the extracellular matrix. After EMT, cells acquire an elongated morphology with front/back polarity, which can be attributed to actin-driven protrusion formation as well as the gain of vimentin expression. Consequently, cells can deform and remodel the surrounding matrix in order to facilitate local invasion. In this review, we highlight recent bioengineering approaches to elucidate EMT and functional changes in the cytoskeleton. First, we review transitions between multicellular clusters and dispersed individuals on planar surfaces, which often exhibit coordinated behaviors driven by leader cells and EMT. Second, we consider the functional role of vimentin, which can be probed at subcellular length scales and within confined spaces. Third, we discuss the role of topographical patterning and EMT via a contact guidance like mechanism. Finally, we address how multicellular clusters disorganize and disseminate in 3D matrix. These new technologies enable controlled physical microenvironments and higher-resolution spatiotemporal measurements of EMT at the single cell level. In closing, we consider future directions for the field and outstanding questions regarding EMT and the cytoskeleton for human cancer progression. Video Abstract.

Growth factor dependent changes in nanoscale architecture of focal adhesions

Focal adhesions (FAs) are flat elongated structures that mediate cell migration and link the cytoskeleton to the extracellular matrix. Along the vertical axis FAs were shown to be composed of three layers. We used structured illumination microscopy to examine the longitudinal distribution of four hallmark FA proteins, which we also used as markers for these layers. At the FA ends pointing towards the adherent membrane edge (heads), bottom layer protein paxillin protruded, while at the opposite ends (tails) intermediate layer protein vinculin and top layer proteins zyxin and VASP extended further. At the tail tips, only intermediate layer protein vinculin protruded. Importantly, head and tail compositions were altered during HGF-induced scattering with paxillin heads being shorter and zyxin tails longer. Additionally, FAs at protruding or retracting membrane edges had longer paxillin heads than FAs at static edges. These data suggest that redistribution of FA-proteins with respect to each other along FAs is involved in cell movement.

Simple Synthesis of a Heterocyclophane Exhibiting Anti-c-Met Activity by Acting as a Hatch Blocking Access to the Active Site*

A simple approach to the synthesis of heterocyclophane consisting of two 4,4'-bithiazoles has been developed in mild conditions. The heterocyclophane with two short chains was conveniently prepared by Hantzsch thiazoles synthesis using the reaction of 3-tert-butoxycarbonyl-3-azapentanethiocarboxamide with 1,4-dibromobutane-2,3-dione in methanol under reflux for only 15 min. Amino groups at the linkers of this heterocyclophane can be functionalized to give acylated and carbamate derivatives. Their properties as protein kinase inhibitors were investigated, and one of the heterocyclophanes exhibited specific anti-activity for c-mesenchymal epithelial transition factor (IC50 =603 nm), among seven types of protein kinases investigated. The computational site identification by ligand competitive saturation method was used to determine why the one heterocyclophane exhibited strong anti-activity for c-mesenchymal epithelial transition factor.

HGF/c-Met signaling regulates early differentiation of placental trophoblast cells

Depletion of hepatocyte growth factor (HGF) or mesenchymal-epithelial transition factor (c-Met) in mice leads to fetal lethality and placental maldevelopment. However, the dynamic change pattern of HGF/c-Met signaling during placental development and its involvement in the early differentiation of trophoblasts remain to be elucidated. In this study, using in situ hybridization assay, we elaborately demonstrated the spatial-temporal expression of Hgf and c-Met in mouse placenta from E5.5, the very early stage after embryonic implantation, to E12.5, when the placental structure is well developed. The concentration of the soluble form of c-Met (sMet) in maternal circulation peaked at E10.5. By utilizing the induced differentiation model of mouse trophoblast stem cells (mTSCs), we found that HGF significantly promoted mTSC differentiation into syncytiotrophoblasts (STBs) and invasive parietal trophoblast giant cells (PTGCs). Interestingly, sMet efficiently reversed the effect of HGF on mTSC differentiation. These findings indicate that HGF/c-Met signaling participates in regulating placental trophoblast cell fate at the early differentiation stage and that sMet acts as an endogenous antagonist in this aspect.

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.

HGF/MET Signaling in Malignant Brain Tumors

Hepatocyte growth factor (HGF) ligand and its receptor tyrosine kinase (RTK) mesenchymal-epithelial transition factor (MET) are important regulators of cellular processes such as proliferation, motility, angiogenesis, and tissue regeneration. In healthy adult somatic cells, this ligand and receptor pair is expressed at low levels and has little activity except when tissue injuries arise. In cancer cells, HGF/MET are often overexpressed, and this overexpression is found to correlate with tumorigenesis, metastasis, and poorer overall prognosis. This review focuses on the signaling of these molecules in the context of malignant brain tumors. RTK signaling pathways are among the most common and universally dysregulated pathways in gliomas. We focus on the role of HGF/MET in the following primary malignant brain tumors: astrocytomas, glioblastomas, oligodendrogliomas, ependymomas, and embryonal central nervous system tumors (including medulloblastomas and others). Brain metastasis, as well as current advances in targeted therapies, are also discussed.

Increased RAB31 Expression in Cancer-Associated Fibroblasts Promotes Colon Cancer Progression Through HGF-MET Signaling

RAB family proteins participate in the dynamic regulation of cellular membrane compartments and are dysregulated in a variety of tumor types, which may alter the biological properties of cancer cells such as proliferation, migration, and invasion. In our previous study, we found that Ras-related protein Rab-31 (RAB31) expression was increased in late-stage colorectal cancer (CRC). The role of RAB31 has never been investigated in CRC. In this study, we found that expression of RAB31 in the tumor stroma but not cancer cells of colon cancer predicted poor survival. RAB31 can be detected in primary cancer-associated fibroblasts (CAFs) and paired normal fibroblasts. Conditioned medium (CM) from RAB31 overexpressing CAFs significantly promoted migration of colon cancer cell lines in vitro and in vivo. This process may be mediated by paracrine action of hepatocyte growth factor (HGF), which was increased in the CM of RAB31-overexpressing CAFs. Blockade of HGF/MET signaling by drug inhibition, knockdown of mesenchymal to epithelial transition factor (MET) in RKO, or antibody neutralization of HGF abolished migration of RKO cells mediated by RAB31 expression in CAFs. We propose that in colon cancer, increased RAB31 expression in CAFs may contribute to tumor progression by regulating the secretion of HGF in the tumor stroma.

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.

The Role of Receptor Tyrosine Kinases in Lassa Virus Cell Entry

The zoonotic Old World mammarenavirus Lassa (LASV) causes severe hemorrhagic fever with high mortality and morbidity in humans in endemic regions. The development of effective strategies to combat LASV infections is of high priority, given the lack of a licensed vaccine and restriction on available treatment to off-label use of ribavirin. A better understanding of the fundamental aspects of the virus's life cycle would help to improve the development of novel therapeutic approaches. Host cell entry and restriction factors represent major barriers for emerging viruses and are promising targets for therapeutic intervention. In addition to the LASV main receptor, the extracellular matrix molecule dystroglycan (DG), the phosphatidylserine-binding receptors of the Tyro3/Axl/Mer (TAM), and T cell immunoglobulin and mucin receptor (TIM) families are potential alternative receptors of LASV infection. Therefore, the relative contributions of candidate receptors to LASV entry into a particular human cell type are a complex function of receptor expression and functional DG availability. Here, we describe the role of two receptor tyrosine kinases (RTKs), Axl and hepatocyte growth factor receptor (HGFR), in the presence and absence of glycosylated DG for LASV entry. We found that both RTKs participated in the macropinocytosis-related LASV entry and, regardless of the presence or absence of functional DG, their inhibition resulted in a significant antiviral effect.

A novel immunohistochemical scoring system reveals associations of C-terminal MET, ectodomain shedding, and loss of E-cadherin with poor prognosis in oral squamous cell carcinoma

Using tissue microarrays, it was shown that membranous C-terminal MET immunoreactivity and ectodomain (ECD) shedding are associated with poor prognosis in oral cancer. Seen the potential diagnostic value, extrapolation of these results to whole-tissue sections was investigated. Because MET orchestrates epithelial-to-mesenchymal transition (EMT), the results were benchmarked to loss of E-cadherin, a readout for EMT known to be associated with poor prognosis. C-terminal MET, N-terminal MET, and E-cadherin immunoreactivities were examined on formalin-fixed paraffin-embedded parallel sections of 203 oral cancers using antibody clones D1C2, A2H2-3, and NCH-38. Interantibody and intra-antibody relations were examined using a novel scoring system, nonparametric distribution, and median tests. Survival analyses were used to examine the prognostic value of the observed immunoreactivities. Assessment of the three clones revealed MET protein status (no, decoy, transmembranous C-terminal positive), ECD shedding, and EMT. For C-terminal MET-positive cancers, D1C2 immunoreactivity is independently associated with poor overall survival (hazard ratio [HR] = 2.40; 95% confidence interval [CI] = 1.25 to 4.61; and P = 0.008) and disease-free survival (HR = 1.83; 95% CI = 1.07-3.14; P = 0.027). For both survival measures, this is also the case for ECD shedding (43.4%, with HR = 2.30; 95% CI = 1.38 to 3.83; and P = 0.001 versus HR = 1.87; 95% CI = 1.19-2.92; P = 0.006) and loss of E-cadherin (55.3%, with HR = 2.21; 95% CI = 1.30 to 3.77; and P = 0.004 versus HR = 1.90; 95% CI = 1.20-3.01; P = 0.007). The developed scoring system accounts for MET protein status, ECD shedding, and EMT and is prognostically informative. These findings may contribute to development of companion diagnostics for MET-based targeted therapy.