Contribution of Bcl-2, but Not Bcl-xL and Bax, to Antiapoptotic Actions of Hepatocyte Growth Factor in Hypoxia-Conditioned Human Endothelial Cells

Single-cell dissection of the multicellular ecosystem and molecular features underlying microvascular invasion in HCC

BACKGROUND AND AIMS

Microvascular invasion (MVI) is a crucial pathological hallmark of HCC that is closely associated with poor outcomes, early recurrence, and intrahepatic metastasis following surgical resection and transplantation. However, the intricate tumor microenvironment and transcriptional programs underlying MVI in HCC remain poorly understood.

APPROACH AND RESULTS

We performed single-cell RNA sequencing of 46,789 individual cells from 10 samples of MVI+ (MVI present) and MVI- (MVI absent) patients with HCC. We conducted comprehensive and comparative analyses to characterize cellular and molecular features associated with MVI and validated key findings using external bulk, single-cell, and spatial transcriptomic datasets coupled with multiplex immunofluorescence assays. The comparison identified specific subtypes of immune and stromal cells critical to the formation of the immunosuppressive and pro-metastatic microenvironment in MVI+ tumors, including cycling T cells, lysosomal associated membrane protein 3+ dendritic cells, triggering receptor expressed on myeloid cells 2+ macrophages, myofibroblasts, and arterial i endothelial cells. MVI+ malignant cells are characterized by high proliferation rates, whereas MVI- malignant cells exhibit an inflammatory milieu. Additionally, we identified the midkine-dominated interaction between triggering receptor expressed on myeloid cells 2+ macrophages and malignant cells as a contributor to MVI formation and tumor progression. Notably, we unveiled a spatially co-located multicellular community exerting a dominant role in shaping the immunosuppressive microenvironment of MVI and correlating with unfavorable prognosis.

CONCLUSIONS

This study provides a comprehensive single-cell atlas of MVI in HCC, shedding light on the complex multicellular ecosystem and molecular features associated with MVI. These findings deepen our understanding of the underlying mechanisms driving MVI and provide valuable insights for improving clinical diagnosis and developing more effective treatment strategies.

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.

Effects of the secretome of human Wharton's jelly mesenchymal stem cells on the proliferation and apoptosis gene expression of the retinal pigmented epithelium

Human retinal pigmented epithelium (RPE) can undergo an uncontrolled proliferation in some disorders such as retinal detachment associated with proliferative vitreoretinopathy (PVR). The present study was conducted to evaluate the effect of the conditioned medium secreted by human Wharton's jelly mesenchymal stem cells (WJMSCs-CM) on the proliferation and apoptosis gene expression of the RPE. WJMSCs-CM was collected from WJMSCs after two periods of 24-h and 9-h culture in serum-free medium. RPE cells were cultured in WJMSCs-CM versus serum-deprived media for 24 h. The effect of WJMSCs-CM on RPE cell proliferation was determined using the MTT assay. Relative expression of apoptotic genes (Bcl2, Bax, and IL-1B) was also assessed by real-time PCR. MTT assay demonstrated that RPE cell viability was reduced significantly in WJMSCs-CM treated RPE cells compared to those cultured in serum-deprived medium (64.23 ± 2.44 vs 100.10 ± 5.68; P = 0.006). Moreover, the expression of anti-apoptotic Bcl2 was significantly decreased in WJMSCs-CM compared to serum-deprived medium (0.52 ± 0.06 in WJMSCs-CM vs 1.02 ± 0.2 in serum-free treatment; P = 0.03), while the expression of pro-apoptotic biomarkers of Bax and IL-1B was not significantly different between the two treatments. The represented data showed that WJMSCs-CM can induce apoptosis in RPE cells in vitro through activating apoptosis pathways. This proof-of-the-concept study provides basic evidence for the possible effect of WJMSCs-CM on preventing PVR.

Therapeutic Angiogenesis by a "Dynamic Duo": Simultaneous Expression of HGF and VEGF165 by Novel Bicistronic Plasmid Restores Blood Flow in Ischemic Skeletal Muscle

Therapeutic angiogenesis is a promising strategy for relief of ischemic conditions, and gene delivery was used to stimulate blood vessels' formation and growth. We have previously shown that intramuscular injection of a mixture containing plasmids encoding vascular endothelial growth factor (VEGF)165 and hepatocyte growth factor (HGF) leads to restoration of blood flow in mouse ischemic limb, and efficacy of combined delivery was superior to each plasmid administered alone. In this work, we evaluated different approaches for co-expression of HGF and VEGF165 genes in a panel of candidate plasmid DNAs (pDNAs) with internal ribosome entry sites (IRESs), a bidirectional promoter or two independent promoters for each gene of interest. Studies in HEK293T culture showed that all plasmids provided synthesis of HGF and VEGF165 proteins and stimulated capillary formation by human umbilical vein endothelial cells (HUVEC), indicating the biological potency of expressed factors. Tests in skeletal muscle explants showed a dramatic difference and most plasmids failed to express HGF and VEGF165 in a significant quantity. However, a bicistronic plasmid with two independent promoters (cytomegalovirus (CMV) for HGF and chicken b-actin (CAG) for VEGF165) provided expression of both grow factors in skeletal muscle at an equimolar ratio. Efficacy tests of bicistronic plasmid were performed in a mouse model of hind limb ischemia. Intramuscular administration of plasmid induced significant restoration of perfusion compared to an empty vector and saline. These findings were supported by increased CD31+ capillary density in animals that received pHGF/VEGF. Overall, our study reports a first-in-class candidate gene therapy drug to deliver two pivotal angiogenic growth factors (HGF and VEGF165) with properties that provide basis for future development of treatment for an unmet medical need-peripheral artery disease and associated limb ischemia.

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.

Multipotent Neurotrophic Effects of Hepatocyte Growth Factor in Spinal Cord Injury

Spinal cord injury (SCI) results in neural tissue loss and so far untreatable functional impairment. In addition, at the initial injury site, inflammation induces secondary damage, and glial scar formation occurs to limit inflammation-mediated tissue damage. Consequently, it obstructs neural regeneration. Many studies have been conducted in the field of SCI; however, no satisfactory treatment has been established to date. Hepatocyte growth factor (HGF) is one of the neurotrophic growth factors and has been listed as a candidate medicine for SCI treatment. The highlighted effects of HGF on neural regeneration are associated with its anti-inflammatory and anti-fibrotic activities. Moreover, HGF exerts positive effects on transplanted stem cell differentiation into neurons. This paper reviews the mechanisms underlying the therapeutic effects of HGF in SCI recovery, and introduces recent advances in the clinical applications of HGF therapy.

Inhibition of Nuclear Factor Kappa B Prevents the Development of Experimental Periapical Lesions

INTRODUCTION

Nuclear factor kappa B (NF-κB) is an important transcriptional regulator of angiogenesis involving B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) signaling pathways. Thus, inhibition of NF-κB may suppress the development of periapical lesions via blockage of angiogenesis. Accordingly, we examined the effects of NF-κB decoy oligodeoxynucleotide (ODN) treatment on experimentally induced periapical lesions.

METHODS

Periapical lesions were induced in the mandibular first molars of 5-week-old male Wistar rats by the application of lipopolysaccharide to the pulp. NF-κB decoy ODN or NF-κB decoy scramble (control) was injected intraperitoneally every 7 days, starting 1 day before pulp exposure. After 28 days, the samples were retrieved, and digital radiographs were taken for radiomorphometry. Samples were processed for (1) immunohistochemistry of CD31, Bcl-2, and Bax; (2) laser capture microdissection to analyze Bcl-2, Bax, chemokine (C-X-C motif) ligand 1 (CXCL1), CXC receptor 2 (CXCR2), and vascular endothelial cell growth factor receptor 2 (VEGFR2) messenger RNA (mRNA) expression in CD31+ endothelial cells; (3) enzyme-linked immunosorbent assay to determine NF-κB/p65 activity; and (4) Western blotting for vascular endothelial growth factor expression.

RESULTS

NF-κB decoy ODN treatment significantly reduced lesion size, NF-κB/p65 activity, and the density of CD31+ endothelial cells in the lesion. NF-κB decoy ODNs also down-regulated CXCL1, CXCR2, and VEGFR2 mRNAs and up-regulated Bax mRNA in endothelial cells but did not affect Bcl2 mRNA in endothelial cells. Vascular endothelial growth factor protein expression in the lesions was significantly decreased.

CONCLUSIONS

The inhibition of NF-κB activity by decoy ODN treatment suppressed the development of experimentally induced periapical lesions with a concomitant reduction in angiogenic responses in endothelial cells.

Human hepatocyte growth factor inhibits early neointima formation in rabbit abdominal aortae following ultrasound-guided balloon injury

The present study investigated the effects of in vivo gene transfer of human hepatocyte growth factor (hHGF) on neointima formation in rabbit abdominal aortae following ultrasound‑guided balloon injury. New Zealand white rabbits were randomly divided into four groups: endothelium injury alone (EI), endothelium injury with control vector transfection (EI‑V), endothelium injury with hHGF transfection (EI‑HGF), and hHGF transfection alone without endothelium injury (HGF). Endothelial injury was established by scraping the abdominal aortic wall using a balloon catheter under the guidance of a transabdominal ultrasound. hHGF gene transfer was performed 7 days following injury. hHGF mRNA and protein expression levels were determined at 3, 7, 14 and 21 days following transfection. Neointima formation was assessed by histopathological analysis at 14 and 28 days following injury. hHGF mRNA and protein expression levels were detected in the target abdominal aortae in EI‑HGF and HGF groups with the greatest levels observed 3 days following transfection, and their levels dropped below detection limits at 21 days following transfection. hHGF was not detectable in the EI and EI‑V groups throughout the experiment. The neointimal area and the neointima to media ratio in the EI‑HGF group were significantly decreased compared with those in the EI or EI‑V group at 14 days following injury. However, no differences were observed at 28 days following injury. The present study demonstrated that in vivo hHGF gene transfer inhibits the early formation of neointima in balloon‑injured rabbit abdominal aortae.

An amino acid-based oral rehydration solution (AA-ORS) enhanced intestinal epithelial proliferation in mice exposed to radiation

Destruction of clonogenic cells in the crypt following irradiation are thought to cause altered gastrointestinal function. Previously, we found that an amino acid-based oral rehydration solution (AA-ORS) improved gastrointestinal function in irradiated mice. However, the exact mechanisms were unknown. Electrophysiology, immunohistochemistry, qPCR, and Western blot analysis were used to determine that AA-ORS increased proliferation, maturation, and differentiation and improved electrolyte and nutrient absorption in irradiated mice. A single-hit, multi-target crypt survival curve showed a significant increase in crypt progenitors in irradiated mice treated with AA-ORS for six days (8.8 ± 0.4) compared to the saline-treated group (6.1 ± 0.3; P < 0.001) without a change in D₀ (4.8 ± 0.1 Gy). The D_q values increased from 8.8 ± 0.4 Gy to 10.5 ± 0.5 Gy with AA-ORS treatment (P < 0.01), indicating an increased radiation tolerance of 1.7 Gy. We also found that AA-ORS treatment (1) increased Lgr5⁺, without altering Bmi1 positive cells; (2) increased levels of proliferation markers (Ki-67, p-Erk, p-Akt and PCNA); (3) decreased apoptosis markers, such as cleaved caspase-3 and Bcl-2; and (4) increased expression and protein levels of NHE3 and SGLT1 in the brush border membrane. This study shows that AA-ORS increased villus height and improved electrolyte and nutrient absorption.

The hepatocyte growth factor isoform NK2 activates motogenesis and survival but not proliferation due to lack of Akt activation

Hepatocyte growth factor (HGF) is a pleiotrophic factor involved in cellular proliferation, migration and morphogenesis. HGF is required for normal tissue and organ development during embryogenesis, but in the adult HGF has been demonstrated to drive normal tissue repair and inhibit fibrotic remodeling. HGF has two naturally occurring human isoforms as a result of alternative splicing, NK1 and NK2. While NK1 has been defined as an agonist for HGF receptor, Met, NK2 is defined as a partial Met antagonist. Furthermore, under conditions of fibrotic remodeling, NK2 is still expressed while full length HGF is suppressed. Furthermore, the mechanism by which NK2 partially signals through Met is not completely understood. Here, we investigated the mitogenic, motogenic, and anti-apoptotic activities of NK2 compared with full length HGF in primary human bronchial epithelial cells (BEpC) and bovine pulmonary artery endothelial cells (PAEC). In human BEpC, NK2 partial activated Met, inducing Met phosphorylation at Y1234/1235 in the tyrosine-kinase domain but not at Y1349 site in the multifunctional docking domain. Partial phosphorylation of Met by NK2 resulted in activation of MAPK and STAT3, but not AKT. This correlated with motogenesis and survival in a MAPK-dependent manner, but not cell proliferation. Overexpression of a constitutively active AKT complemented NK2 signaling, allowing NK2 to induce cell proliferation. These data indicate that NK2 and HGF drive motogenic and anti-apoptotic signaling but only HGF drives cell proliferation by activating AKT-pathway signaling. These results have implications for the biological consequences of differential regulation of the two isoforms under pro-fibrotic conditions.

Hepatocyte Growth Factor from a Clinical Perspective: A Pancreatic Cancer Challenge

Pancreatic cancer is the fourth leading cause of cancer-related deaths in the United States and incidence rates are rising. Both detection and treatment options for pancreatic cancer are limited, providing a less than 5% five-year survival advantage. The need for new biomarkers for early detection and treatment of pancreatic cancer demands the efficient translation of bench knowledge to provide clinical benefit. One source of therapeutic resistance is the pancreatic tumor microenvironment, which is characterized by desmoplasia and hypoxia making it less conducive to current therapies. A major factor regulating desmoplasia and subsequently promoting chemoresistance in pancreatic cancer is hepatocyte growth factor (HGF), the sole ligand for c-MET (mesenchymal-epithelial transition), an epithelial tyrosine kinase receptor. Binding of HGF to c-MET leads to receptor dimerization and autophosphorylation resulting in the activation of multiple cellular processes that support cancer progression. Inhibiting activation of c-MET in cancer cells, in combination with other approaches for reducing desmoplasia in the tumor microenvironment, might significantly improve the success of chemotherapy. Therefore, HGF makes a potent novel target for developing therapeutic strategies in combination with existing drugs for treating pancreatic adenocarcinoma. This review provides a comprehensive analysis of HGF and its promising potential as a chemotherapeutic target for pancreatic cancer.

Hepatocyte growth factor mimetic protects lateral line hair cells from aminoglycoside exposure

Loss of sensory hair cells from exposure to certain licit drugs (e.g., aminoglycoside antibiotics, platinum-based chemotherapy agents) can result in permanent hearing loss. Here we ask if allosteric activation of the hepatocyte growth factor (HGF) cascade via Dihexa, a small molecule drug candidate, can protect hair cells from aminoglycoside toxicity. Unlike native HGF, Dihexa is chemically stable and blood-brain barrier permeable. As a synthetic HGF mimetic, it forms a functional ligand by dimerizing with endogenous HGF to activate the HGF receptor and downstream signaling cascades. To evaluate Dihexa as a potential hair cell protectant, we used the larval zebrafish lateral line, which possesses hair cells that are homologous to mammalian inner ear hair cells and show similar responses to toxins. A dose-response relationship for Dihexa protection was established using two ototoxins, neomycin and gentamicin. We found that a Dihexa concentration of 1 μM confers optimal protection from acute treatment with either ototoxin. Pretreatment with Dihexa does not affect the amount of fluorescently tagged gentamicin that enters hair cells, indicating that Dihexa’s protection is likely mediated by intracellular events and not by inhibiting aminoglycoside entry. Dihexa-mediated protection is attenuated by co-treatment with the HGF antagonist 6-AH, further evidence that HGF activation is a component of the observed protection. Additionally, Dihexa’s robust protection is partially attenuated by co-treatment with inhibitors of the downstream HGF targets Akt, TOR and MEK. Addition of an amino group to the N-terminal of Dihexa also attenuates the protective response, suggesting that even small substitutions greatly alter the specificity of Dihexa for its target. Our data suggest that Dihexa confers protection of hair cells through an HGF-mediated mechanism and that Dihexa holds clinical potential for mitigating chemical ototoxicity.

Therapeutic potential of hepatocyte growth factor against cerebral ischemia (Review)

The effective treatment for cerebral ischemia has not yet been established. Hepatocyte growth factor (HGF) is a potent pleiotropic cytokine that is involved in cell and tissue regeneration, including in the central nervous system. Studies have demonstrated that an exogenous administration of HGF protects brain tissue from ischemic damage. In response to binding to the receptor c-Met, HGF activates the downstream signaling pathways (including the phosphatidylinositol 3-kinase/Akt, Ras/MAPK and signal transducer and activator of transcription pathways) which leads to various cellular responses involved in angiogenesis, glial scar formation, anti-apoptosis and neurogenesis. The purpose of this review is to summarize the present understanding of the therapeutic potential of HGF in cerebral ischemia.

Neferine prevented hyperglycemia-induced endothelial cell apoptosis through suppressing ROS/Akt/NF-κB signal

Diabetes mellitus has been identified as a major risk factor for cardiovascular diseases. High glucose-induced endothelial dysfunction and apoptosis is an important pathological feature of diabetic vasculopathy. Neferine, an alkaloid ingredient in lotus seed embryo has many biological actions such as anticancer and antioxidant. But little is known about whether Neferine protects endothelial cells against high glucose-induced oxidative stress and apoptosis. The present study was conducted to investigate the preventive effects of Neferine on hyperglycemia-induced injury of human umbilical vein endothelial cells (HUVECs). Our study showed that Neferine pretreatment effectively suppressed high glucose-induced HUVECs apoptosis. Also, Neferine pretreatment inhibited the augment of reactive oxygen species (ROS) in high glucose-treated HUVECs. The changes of SOD and MDA level in high glucose-treated HUVECs were also prevented by Neferine. Further study showed that Neferine did not affect the phosphorylation of JNK and p38 in high glucose-treated HUVECs. Interestingly, Neferine markedly inhibited high glucose-induced activation of PI3K/Akt pathway in HUVECs. High glucose-induced activation of NF-κB signal was also obviously suppressed by Neferine pretreatment. Collectively, we found that Neferine inhibited high glucose-induced endothelial apoptosis via blocking ROS/Akt/NF-κB pathway, which provides the evidence for using Neferine to treat diabetic vasculopathy.

Biochemical and immunomorphological evaluation of hepatocyte growth factor and c-Met pathway in patients with critical limb ischemia

OBJECTIVES

Hepatocyte growth factor (HGF), the c-Met receptor, and hypoxia-inducible factor (HIF) are crucial for regenerative processes including ischemic wound healing. The aims of the present study are (a) to analyze the tissue c-Met and HIF-1α expression in skin from patients with critical limb ischemia (CLI); (b) to compare the serum HGF levels of CLI and control subjects.

METHODS

This is a prospective, controlled, single-center study. Thirty-seven patients were enrolled. A skin sample adjacent to the ischemic lesion was taken from 20 patients with CLI; skin samples were taken from the surgical wounds of 17 patients surgically treated for abdominal aortic aneurysm as healthy controls. Serum samples were taken in all cases. Samples were formalin fixed, paraffin embedded, and routinely processed. Tissue inflammation was histologically assessed. Immunohistochemistry was performed with antibodies against total c-Met receptor, activated Met (p-Met), and HIF-1α. RT-polymerase chain reaction was used to quantify HIF-1α mRNA. The enzyme-linked immunosorbent assay was performed to evaluate serum HGF levels.

RESULTS

With immunohistochemistry, while total c-Met was unchanged, different patterns of p-Met positivity were observed between CLI and control cases (p < .001). In particular, CLI skin showed a total negativity or membrane positivity for p-Met (19/20 cases), while control skin mainly showed cytoplasmic positivity in the epidermal basal layer (16/17 cases). HIF-1α was diffusely lost in CLI, but HIF-1α mRNA was threefold higher than in controls. Finally, mean serum HGF levels were 590.5 pg/mL and 2380.0 pg/mL in CLI and control groups respectively (p < .001).

CONCLUSIONS

In CLI patients a significant decrease in serum HGF levels, concomitant with a loss of skin HIF-1α stabilization and a lack of c-Met phosphorylation were seen, probably driving a decrease in wound-healing functions. The next hypothesis is that HGF application might reactivate the c-Met receptor, stabilizing the normal wound healing process.

Angiogenesis and the tumor microenvironment: vascular endothelial growth factor and beyond

Our understanding of the dynamic tumor microenvironment (TME) has improved exponentially over the last few decades. In addition to traditional cytotoxic agents, anti-cancer strategies now include numerous molecular-targeted drugs that modulate distinct elements of the TME. Angiogenesis is an underlying promoter of tumor growth, invasion, and metastases. From traditional and emerging angiogenic cytokines and their receptors to novel immune checkpoint inhibitors, regulation of the tumor microenvironment is potentially key in countering tumor progression. In this article, an overview of the architecture of the TME and the orchestration of angiogenesis within the TME is provided. Additionally, traditional and novel angiogenic targets of current interest within the TME are reviewed.

Caspase-generated fragment of the Met receptor favors apoptosis via the intrinsic pathway independently of its tyrosine kinase activity

The receptor tyrosine kinase Met and its ligand, the hepatocyte growth factor, are essential to embryonic development, whereas the deregulation of Met signaling is associated with tumorigenesis. While ligand-activated Met promotes survival, caspase-dependent generation of the p40 Met fragment leads to apoptosis induction - hallmark of the dependence receptor. Although the survival signaling pathways induced by Met are well described, the pro-apoptotic signaling pathways are unknown. We show that, although p40 Met contains the entire kinase domain, it accelerates apoptosis independently of kinase activity. In cell cultures undergoing apoptosis, the fragment shows a mitochondrial localization, required for p40 Met-induced cell death. Fulminant hepatic failure induced in mice leads to the generation of p40 Met localized also in the mitochondria, demonstrating caspase cleavage of Met in vivo. According to its localization, the fragment induces mitochondrial permeabilization, which is inhibited by Bak silencing and Bcl-xL overexpression. Moreover, Met silencing delays mitochondrial permeabilization induced by an apoptotic treatment. Thus, the Met-dependence receptor in addition to its well-known role in survival signaling mediated by its kinase activity, also participates in the intrinsic apoptosis pathway through the generation of p40 Met - a caspase-dependent fragment of Met implicated in the mitochondrial permeabilization process.

Circulating hepatocyte growth factor (HGF) in patients with comorbidity of chronic heart failure, type 2 diabetes mellitus and impaired lipid metabolism

AIM: To evaluate the plasma level of circulating heptocyte growth factor (HGF) in patients with comorbidity of post-infarction chronic heart failure (CHF), type 2 diabetes mellitus (T2DM) and obesity. We also aimed to assess possible correlations between HGF levels and parameters of carbohydrate and lipid metabolism, as well as myocardial functional characteristics and classic biochemical severity markers for CHF.17Сахар ный диабет КардиологияСахарный диабет. 2013;(2):17-25 MATERIALS AND METHODS: We enrolled 100 patients for participation in this study, including the following subgroups: 20 individuals with- out cardiovascular and glycemic disorders, 30 patients with CHF, 25 patients with CHF/T2DM comorbidity and 25 diabetic patients with no signs of heart failure. Quantitative plasma HGF analysis was performed with enzyme-linked immunosorbent assay (ELISA). RESULTS: Plasma HGF was elevated both in patients with CHF and T2DM as measured against healthy control group. The elevation was most prominent in patients with CHF/T2DM comorbidity and was found to correlate with HbA1c level (r=0.52, p=0.03). Plasma HGF also correlated with BMI (r=0.42, p=0007) in a unified study group, though we observed no statistically significant difference between subgroups with a trend toward higher HGF in obese patients with CHF/T2DM comorbidity (626.1?254.1 pg/ml vs 742.0?210.7 pg/ml respectively; p 0.05). Interestingly, plasma HGF was also significantly higher in controls with BMI 30 km/m2 (324.1?107.7 pg/ml vs 436.9?112.3 pg/ml, p=0.03).Circulating HGF correlated with plasma levels of N-terminal fragment of B-type natriuretic peptide (NT-proBNP) and such structural and functional myocardial characteristics as left atrial size and maximum volume along with left ventricular ejection fraction (EF), end-diastolic volume (EDV) and end-diastolic dimension (EDD). CONCLUSION: These findings suggest that HGF may potentially serve as a prediction marker for unfavorable myocardial remodeling and poor prognosis in CHF patients with T2DM and obesity, though this possibility should be further investigated in follow-up studies.

Mouse hepatic oval cells require Met-dependent PI3K to impair TGF-β-induced oxidative stress and apoptosis

We have previously shown that oval cells harboring a genetically inactivated Met tyrosine kinase (Met^−/− oval cells) are more sensitive to TGF-β-induced apoptosis than cells expressing a functional Met (Met^flx/flx), demonstrating that the HGF/Met axis plays a pivotal role in oval cell survival. Here, we have examined the mechanism behind this effect and have found that TGF-β induced a mitochondria-dependent apoptotic cell death in Met^flx/flx and Met^−/− oval cells, associated with a marked increase in levels of the BH3-only proteins Bim and Bmf. Bmf plays a key role during TGF-β-mediated apoptosis since knocking down of BMF significantly diminished the apoptotic response in Met^−/− oval cells. TGF-β also induced oxidative stress accompanied by NADPH oxidase 4 (Nox4) mRNA up-regulation and decreased protein levels of antioxidant enzymes. Antioxidants inhibit both TGF-β-induced caspase 3 activity and Bmf up-regulation, revealing an oxidative stress-dependent Bmf regulation by TGF-β. Notably, oxidative stress-related events were strongly amplified in Met^−/− oval cells, emphasizing the critical role of Met in promoting survival. Pharmacological inhibition of PI3K did impair HGF-driven protection from TGF-β-induced apoptosis and increased sensitivity of Met^flx/flx oval cells to TGF-ß by enhancing oxidative stress, reaching apoptotic indices similar to those obtained in Met^−/− oval cells. Interestingly, both PI3K inhibition and/or knockdown itself resulted in caspase-3 activation and loss of viability in Met^flx/flx oval cells, whereas no effect was observed in Met^−/− oval cells. Altogether, results presented here provide solid evidences that both paracrine and autocrine HGF/Met signaling requires PI3K to promote mouse hepatic oval cell survival against TGF-β-induced oxidative stress and apoptosis.

Cytokines as regulators of proliferation and survival of healthy and malignant peripheral B cells

Adaptive immunity depends on the production and maintenance of a pool of mature peripheral lymphocytes throughout life. The signals regulating the survival of mature splenic B cells have become a major focus in recent studies of B cell immunology. Lasting B cell persistence in the periphery is dependent on survival signals that are transduced by cell surface receptors. Cytokines have been shown to play a critical role in maintaining lymphocyte homeostasis. This review focuses on the role of cytokines and their receptors in the regulation of peripheral B cell survival, with an emphasis on those that have received relatively less attention in the literature.

Overexpression of the human ubiquitin E3 ligase CUL4A alleviates hypoxia-reoxygenation injury in pheochromocytoma (PC12) cells

The ubiquitin E3 ligase CUL4A plays important roles in diverse cellular processes including carcinogenesis and proliferation. It has been reported that the expression of CUL4A can be induced by hypoxic-ischemic injury. However, the effect of elevated expression of CUL4A on hypoxia-reoxygenation injury is currently unclear. In this study, human CUL4A (hCUL4A) was expressed in rat pheochromocytoma (PC12) cells using adenoviral vector-mediated gene transfer, and the effects of hCUL4A expression on hypoxia-reoxygenation injury were investigated. In PC12 cells subjected to hypoxia and reoxygenation, we found that hCUL4A suppresses apoptosis and DNA damage by regulating apoptosis-related proteins and cell cycle regulators (Bcl-2, caspase-3, p53 and p27); consequently, hCUL4A promotes cell survival. Taken together, our results reveal the beneficial effects of hCUL4A in PC12 cells upon hypoxia-reoxygenation injury.

Hepatocyte growth factor is a significant risk factor for white matter lesions in Japanese type 2 diabetic patients

BACKGROUND

The presence of white matter lesions (WML) is an important prognostic factor for the development of stroke. Elevated hepatocyte growth factor (HGF) levels are associated with a high mortality rate in type 2 diabetic patients. The preliminary study was therefore designed to test the hypothesis that the presence of WML correlates with HGF and insulin resistance in type 2 diabetic patients not receiving insulin treatment.

MATERIAL AND METHODS

Based on brain magnetic resonance imaging, 92 type 2 diabetic patients were divided into two groups: WML-positive group (age 60 +/- 5 years, mean +/- SD, n = 35) and WML-negative group (age 59 +/- 6 years, mean +/- SD, n = 57. The level of blood glucose was assessed by fasting plasma glucose, fasting immunoreactive insulin, homeostasis model assessment (HOMA) index and haemoglobin A1c (HbA1c).

RESULTS

The body mass index was higher in the WML-positive group than that in the WML-negative group (P < 0.005). Plasma levels of triglycerides were higher while high-density lipoprotein cholesterol was lower in the WML-positive group than in the WML-negative group (P < 0.01 and P < 0.0001 respectively). Fasting plasma glucose (P < 0.0001), insulin concentrations (P < 0.0001), HOMA index (P < 0.0001) and HGF (< 0.0001) levels were higher in the WML-positive group than in the WML-negative group. Multivariate logistic analysis revealed that WML was independently predicted by the high HGF and insulin resistance (P < 0.0001 and P < 0.0001 respectively).

CONCLUSION

The results of this preliminary study indicate that the presence of WML was associated with the high HGF and insulin resistance in Japanese patients with type 2 diabetes mellitus.

The discovery of hepatocyte growth factor (HGF) and its significance for cell biology, life sciences and clinical medicine

It has been more than 25 years since HGF was discovered as a mitogen of hepatocytes. HGF is produced by stromal cells, and stimulates epithelial cell proliferation, motility, morphogenesis and angiogenesis in various organs via tyrosine phosphorylation of its receptor, c-Met. In fetal stages, HGF-neutralization, or c-Met gene destruction, leads to hypoplasia of many organs, indicating that HGF signals are essential for organ development. Endogenous HGF is required for self-repair of injured livers, kidneys, lungs and so on. In addition, HGF exerts protective effects on epithelial and non-epithelial organs (including the heart and brain) via anti-apoptotic and anti-inflammatory signals. During organ diseases, plasma HGF levels significantly increased, while anti-HGF antibody infusion accelerated tissue destruction in rodents. Thus, endogenous HGF is required for minimization of diseases, while insufficient production of HGF leads to organ failure. This is the reason why HGF supplementation produces therapeutic outcomes under pathological conditions. Moreover, emerging studies delineated key roles of HGF during tumor metastasis, while HGF-antagonism leads to anti-tumor outcomes. Taken together, HGF-based molecules, including HGF-variants, HGF-fragments and c-Met-binders are available as regenerative or anti-tumor drugs. Molecular analysis of the HGF-c-Met system could provide bridges between basic biology and clinical medicine.

Dysregulated apoptosis through the intrinsic pathway in the internal spermatic vein of patients with varicocele

BACKGROUND/PURPOSE

Apoptosis plays a critical role in various physiological processes. Varicocele is the most common cause of male infertility in adults. The dilated and thickened wall of the internal spermatic vein (ISV) in varicocele is considered similar to that in varicose veins. We investigated apoptotic protein expression in the ISV of varicocele, including Bcl-2, Fas, caspase-8 and caspase-9, to determine the intrinsic or extrinsic pathway.

METHODS

The study group consisted of 10 patients with grade 3 left varicocele. The control group consisted of 10 patients with left indirect inguinal hernia. A 1-cm section of ISV was resected, using left inguinal incision, from each patient in both groups. The ISV sections were used to detect the mediators that regulate the intrinsic (Bcl-2 and caspase-9) and extrinsic (Fas and caspase-8) apoptotic pathways, by immunoblotting and immunohistochemical staining. Results were analyzed using Student's t tests.

RESULTS

Bcl-2, Fas, caspase-8 and caspase-9 immunoblots from both groups revealed a single band. The relative intensities of the Bcl-2 and caspase-9 protein bands differed significantly between the varicocele and control groups. Thickening of the smooth muscle layer of the ISV was found in patients with varicocele compared with the control group. Bcl-2 overexpression and downregulation of caspase-9 expression were noted in the varicocele group. There was no significant difference in Fas or caspase-8 expression in either group.

CONCLUSION

We showed overexpression of Bcl-2 and downregulation of caspase-9 expression in the ISV under hypoxic stress. This indicated dysregulated apoptosis through the intrinsic pathway in the ISV of patients with varicocele. To the best of our knowledge, this is the first study of the apoptotic pathway in the human ISV. Additional studies are needed to establish whether adjunctive hyperbaric oxygen therapy reduces the recurrence rate after varicocelectomy.

Hepatocyte growth factor levels are associated with the results of 123I-metaiodobenzylguanidine myocardial scintigraphy in patients with type 2 diabetes mellitus

Elevated hepatocyte growth factor (HGF) levels and cardiovascular autonomic dysfunction are associated with a high mortality rate in patients with type 2 diabetes mellitus. We tested the hypothesis that elevated HGF is associated with insulin resistance and cardiovascular autonomic dysfunction in patients with type 2 diabetes mellitus not receiving insulin treatment. The study group consisted of 21 type 2 diabetes mellitus patients with high HGF levels (>0.26 ng/mL, 58 +/- 5 years old, high-HGF group). The control group consisted of 25 type 2 diabetes mellitus patients with normal HGF levels (<or=0.26 ng/mL, 58 +/- 9 years old, normal-HGF group). Cardiovascular autonomic function was assessed by baroreflex sensitivity, heart rate variability, plasma norepinephrine concentrations, and cardiac (123)I-metaiodobenzylguanidine (MIBG) scintigraphy. Early and delayed (123)I-MIBG myocardial uptake values were lower (P < .005 and P < .01, respectively) and the percentage of washout rate of (123)I-MIBG was higher (P < .001) in the high-HGF group than in the normal-HGF group. The fasting plasma insulin concentrations (P < .0001) and the homeostasis model assessment index values (P < .0001) were higher in the high-HGF group than in the normal-HGF group. Multiple regression analysis revealed that the level of HGF was independently predicted by the homeostasis model assessment index values and the myocardial uptake of (123)I-MIBG at the delayed phase. Our results demonstrate that high levels of HGF are associated with depressed cardiovascular autonomic function and insulin resistance in patients with type 2 diabetes mellitus.

The polyamines regulate endothelial cell survival during hypoxic stress through PI3K/AKT and MCL-1

Hypoxia-dependent angiogenesis is an inherent feature of solid tumors, and a better understanding of the molecular mechanisms of hypoxic cell-death should provide additional targets for cancer therapy. Here, we show a novel role of the polyamines in endothelial cell (EC) survival during hypoxia. Polyamine depletion by specific inhibition of ornithine decarboxylase was shown to protect ECs from hypoxia-induced apoptosis. Inhibition of the polyamines resulted in a significant induction of PI3K/AKT and its down-stream target MCL-1, i.e. an anti-apoptotic member of the BCL-2 family. Specific inhibitors of PI3K reversed the decrease of hypoxia-induced apoptosis as well as the induction of MCL-1 in polyamine-deprived cells. Moreover, siRNA-mediated down-regulation of MCL-1 was found to counter-act the protective effect of polyamine inhibition. We conclude that the polyamines regulate hypoxia-induced apoptosis in ECs through PI3K/AKT and MCL-1 dependent pathways. Our results may have important implications for the modulation of hypoxia-driven neovascularization.

VEGF and TGF-beta are required for the maintenance of the choroid plexus and ependyma

Although the role of vascular endothelial growth factor (VEGF) in developmental and pathological angiogenesis is well established, its function in the adult is less clear. Similarly, although transforming growth factor (TGF) β is involved in angiogenesis, presumably by mediating capillary (endothelial cell [EC]) stability, its involvement in quiescent vasculature is virtually uninvestigated. Given the neurological findings in patients treated with VEGF-neutralizing therapy (bevacizumab) and in patients with severe preeclampsia, which is mediated by soluble VEGF receptor 1/soluble Fms-like tyrosine kinase receptor 1 and soluble endoglin, a TGF-β signaling inhibitor, we investigated the roles of VEGF and TGF-β in choroid plexus (CP) integrity and function in adult mice. Receptors for VEGF and TGF-β were detected in adult CP, as well as on ependymal cells. Inhibition of VEGF led to decreased CP vascular perfusion, which was associated with fibrin deposition. Simultaneous blockade of VEGF and TGF-β resulted in the loss of fenestrae on CP vasculature and thickening of the otherwise attenuated capillary endothelium, as well as the disappearance of ependymal cell microvilli and the development of periventricular edema. These results provide compelling evidence that both VEGF and TGF-β are involved in the regulation of EC stability, ependymal cell function, and periventricular permeability.

HGF protects cultured cortical neurons against hypoxia/reoxygenation induced cell injury via ERK1/2 and PI-3K/Akt pathways

Hepatocyte growth factor (HGF) has been revealed to exert multipotent activities on a variety of cells. In this study, we investigated whether HGF had a direct neuroprotection on cultured cerebral cortical neurons subjected to hypoxia/reoxygenation (H/R) and explored the intracellular signalings mediated the effects. The decrease in cell viability and increase in number of apoptotic cells resulting from H/R were significantly prevented by HGF pre-treatment. HGF stimulated both ERK1/2 and Akt activities in cortical neurons. Inhibition of ERK activation completely abolished the protective effects of HGF, and inhibition of Akt activation reduced, but did not completely eliminate the HGF mediated neuroprotection. It is suggested that the neuroprotection of HGF depend on ERK1/2 pathway, and, to a lesser extent, PI-3K/Akt pathway. In addition, we found that pre-treatment with HGF remarkably attenuated the decrease in expression of Bcl-2 and Bcl-xL induced by H/R, but failed to affect the amount of Bax. It is likely that Bcl-2 and Bcl-xL contribute to the protective effects of HGF.

4-1BB Costimulation of Effector T Cells for Adoptive Immunotherapy of Cancer: Involvement of Bcl Gene Family Members

We previously reported that in vitro costimulation of murine MCA 205 tumor-draining lymph node (TDLN) cells through a third signal, 4-1BB (CD137), in addition to CD3 and CD28 engagement significantly increases T-cell yield and amplifies antitumor responses in adoptive therapy. The increased T-cell yield seemed to be related to inhibition of activation-induced cell death. In this study, using real time-polymerase chain reaction and intracellular staining, we tested our hypothesis that antiapoptotic Bcl gene members are modulated in 4-1BB ligated TDLN cells. TDLN cells activated through 4-1BB in conjunction with CD3/CD28 demonstrated elevated Bcl-2 and Bcl-xL gene and protein expression compared with CD3/CD28 activation. Furthermore, Bcl-2 and/or Bcl-xL inhibition abrogated 4-1BB-conferred rescue of activation-induced cell death in TDLN cells, and as a result, 4-1BB-enhanced TDLN cell yield was abolished. Congenic mice were used as donors for TDLN cells labeled with CFSE to evaluate proliferation and persistence of activated cells after intravenous adoptive transfer. The effector function of transferred cells was assessed by determining the incidence of interferon-gamma-producing cells in response to tumor stimulation in serial blood samples drawn from treated mice using intracellular cytokine staining. CD28 and CD28/4-1BB costimulation significantly enhanced in vivo proliferation and survival of the infused cells compared with CD3 activation. 4-1BB coligation augmented the proliferation and effector function of the infused cells compared with both CD3 and CD3/CD28-activated cells. Characterizing the function of signaling molecules involved in T-cell activation pathways may allow optimization of conditions in the generation of effector T cells for cancer immunotherapy.

Predictors for silent cerebral infarction in patients with chronic renal failure undergoing hemodialysis

In patients with chronic renal failure undergoing hemodialysis (HD), silent cerebral infarctions (SCIs) are associated with high mortality. Levels of hepatocyte growth factor (HGF) increase with renal dysfunction and may be a novel predictor of cerebrovascular events. We examined if HGF is a predictor of SCI in HD patients. Brain magnetic resonance imaging findings were used to divide 50 patients undergoing HD into 2 groups, a group with SCI (age, 61 +/- 8 years, mean +/- SD; n = 27) and a group without SCI (age, 60 +/- 7 years; n = 23). These patients received 24-hour ambulatory blood pressure monitoring. The number of patients with diabetes or hypertension was not different between the 2 groups. We made the following observations: (1) The percentage of smokers was higher in the group with SCI than in the group without SCI (P < .05). (2) Plasma levels of high-density lipoprotein cholesterol were lower and HGF levels were higher in the group with SCI compared with the group without SCI (P < .05 and P < .005, respectively). (3) Systolic ambulatory blood pressure and mean heart rate at night were higher in the group with SCI than in the group without SCI (P < .05). Multiple logistic regression analysis identified HGF as a significant risk factor for SCI (odds ratio, 1.89; 95% confidence interval, 1.57-3.38; P < .005). Our findings indicate that HGF may be a novel useful predictor of SCI in patients with chronic renal failure undergoing HD.

HGF/SF regulates expression of apoptotic genes in MCF-10A human mammary epithelial cells

Hepatocyte growth factor/scatter factor (HGF/SF) induces scattering, morphogenesis, and survival of epithelial cells through activation of the MET tyrosine kinase receptor. HGF/SF and MET are involved in normal development and tumor progression of many tissues and organs, including the mammary gland. In order to find target genes of HGF/SF involved in its survival function, we used an oligonucleotide microarray representing 1,920 genes known to be involved in apoptosis, transcriptional regulation, and signal transduction. MCF-10A human mammary epithelial cells were grown in the absence of serum and treated or not with HGF/SF for 2 h. Total RNA was reverse-transcribed to cDNA in the presence of fluorescent Cy3-dUTP or Cy5-dUTP to generate fluorescently labeled cDNA probes. Microarrays were performed and the ratios of Cy5/Cy3 fluorescence were determined. The expression of three apoptotic genes was modified by HGF/SF, with A20 being upregulated, and DAXX and SMAC being downregulated. These changes of expression were confirmed by real-time quantitative PCR. According to current-knowledge, A20 is antiapoptotic and SMAC is proapoptotic, while a pro- or antiapoptotic function of DAXX is controversial. The fact that HGF/SF upregulates an antiapoptotic gene (A20) and downregulates a proapoptotic gene (SMAC) is in agreement with its survival effect in MCF-10A cells. This study identified novel apoptotic genes regulated by HGF/SF, which can contribute to its survival effect.

Radiation-induced apoptosis along with local and systemic cytokine elaboration is associated with DC plus radiotherapy-mediated renal cell tumor regression

Utilizing melanoma and sarcoma tumor models syngeneic to C57BL/6 mice, we previously reported the antitumor effects of intratumoral (i.t.) administration of dendritic cells (DC) combined with localized radiotherapy (RT). However, the mechanisms underlying the augmented therapeutic effects have yet to be fully defined. Using the BALB/c host, we explored in this study the capacity of RT to augment the therapeutic efficacy of DC in the syngeneic renal cell cancer, Renca. I.t. DC administration combined with RT inhibited tumor growth in a synergistic manner. This extends our previous findings using a different host strain and two histologically distinct tumor models. More importantly, we provide evidence in this report that RT induced significant apoptosis and necrosis in Renca tumor cells, which involved down-regulated expression of Bcl-2 and a concurrent up-regulated expression of Bax. We also found significantly elevated expression of TNFalpha in RT plus DC-treated Renca tumors. Furthermore, splenocytes isolated from DC plus RT-treated mice elaborated higher levels of IL-2, IL-4, IFNgamma and IgG, IgM in response to tumor cells compared with splenocytes from monotherapy-treated hosts. These data support the conclusion that radiotherapy enhanced DC vaccination by inducing tumor cell apoptosis in BABL/c host, and the significantly augmented therapeutic efficacy by RT+DC treatment was associated with an increased local production of TNFalpha as well as an amplified systemic antitumor responses conferred by the combined therapy. I.t. DC administration in concert with localized RT may represent a promising novel regimen for human cancer therapy.

Mechanisms of cell death in oxidative stress

Reactive oxygen or nitrogen species (ROS/RNS) generated endogenously or in response to environmental stress have long been implicated in tissue injury in the context of a variety of disease states. ROS/RNS can cause cell death by nonphysiological (necrotic) or regulated pathways (apoptotic). The mechanisms by which ROS/RNS cause or regulate apoptosis typically include receptor activation, caspase activation, Bcl-2 family proteins, and mitochondrial dysfunction. Various protein kinase activities, including mitogen-activated protein kinases, protein kinases-B/C, inhibitor-of-I-kappaB kinases, and their corresponding phosphatases modulate the apoptotic program depending on cellular context. Recently, lipid-derived mediators have emerged as potential intermediates in the apoptosis pathway triggered by oxidants. Cell death mechanisms have been studied across a broad spectrum of models of oxidative stress, including H2O2, nitric oxide and derivatives, endotoxin-induced inflammation, photodynamic therapy, ultraviolet-A and ionizing radiations, and cigarette smoke. Additionally ROS generated in the lung and other organs as the result of high oxygen therapy or ischemia/reperfusion can stimulate cell death pathways associated with tissue damage. Cells have evolved numerous survival pathways to counter proapoptotic stimuli, which include activation of stress-related protein responses. Among these, the heme oxygenase-1/carbon monoxide system has emerged as a major intracellular antiapoptotic mechanism.

Bcl-2 Overexpression in the Internal Spermatic Vein of Patients with Varicocele

BACKGROUND/PURPOSE

Varicocele is characterized by dilatation and tortuosity of the internal spermatic vein (ISV). Cross sections of ISV showed marked thickening of smooth muscle layer under microscopy. This study examined Bcl-2 (anti-apoptotic protein) expression in the ISV of patients with varicocele.

METHODS

The study group consisted of eight patients with left varicocele, grade 3. The control group consisted of six volunteers with left indirect inguinal hernia. Using a left inguinal surgical incision, a 1-cm section of ISV was resected from each patient in both groups as specimens for immunoblotting and immunohistochemical staining of Bcl-2. Results were analyzed using Student's t test.

RESULTS

Bcl-2 immunoblots from both groups revealed one single band. alpha-tubulin was used as loading control. The average relative intensity of the Bcl-2 was 25.82 +/- 10.53 in the control group and 113.49 +/- 27.49 in the varicocele group. Hematoxylin staining revealed a thickening ISV in the patients with varicocele, predominantly in the muscle layer, which was not found in the control group. Moreover, the intensity of Bcl-2 immunostaining was markedly higher in the study group than in the control group.

CONCLUSION

This study showed Bcl-2 overexpression in the ISV of patients with varicocele. Additional studies are necessary to clarify the molecular mechanisms of varicocele formation and recurrence.

Hepatocyte growth factor protects human endothelial cells against advanced glycation end products-induced apoptosis

Advanced glycation end products (AGEs) form by a non-enzymatic reaction between reducing sugars and biological proteins, which play an important role in the pathogenesis of atherosclerosis. In this study, we assessed AGEs effects on human umbilical vein endothelial cells (HUVECs) growth, proliferation and apoptosis. Additionally, we investigated whether hepatocyte growth factor (HGF), an anti-apoptotic factor for endothelial cells, prevents AGEs-induced apoptosis of HUVECs. HUVECs were treated with AGEs in the presence or absence of HGF. Treatment of HUVECs with AGEs changed cell morphology, decreased cell viability, and induced DNA fragmentation, leading to apoptosis. Apoptosis was induced by AGEs in a dose- and time-dependent fashion. AGEs markedly elevated Bax and decreased NF-kappaB, but not Bcl-2 expression. Additionally, AGEs significantly inhibited cell growth through a pro-apoptotic action involving caspase-3 and -9 activations in HUVECs. Most importantly, pretreatment with HGF protected against AGEs-induced cytotoxicity in the endothelial cells. HGF significantly promoted the expression of Bcl-2 and NF-kappaB, while decreasing the activities of caspase-3 and -9 without affecting Bax level. Our data suggest that AGEs induce apoptosis in endothelial cells. HGF effectively attenuate AGEs-induced endothelial cell apoptosis. These findings provide new perspectives in the role of HGF in cardiovascular disease.

Intravitreous hepatocyte growth factor in patients with proliferative diabetic retinopathy: a case-control study

The aim of the present study was to evaluate the vitreous levels of hepatocyte growth factor (HGF) in patients with proliferative diabetic retinopathy (PDR) and to investigate its relationship with vascular endothelial growth factor (VEGF) and retinopathy activity. In addition, the relationship between intravitreous HGF levels and the presence of epiretinal membranes (ERM), as well as the expression of c-Met in ERM were also investigated. In this case-control study, serum and vitreous samples as well as ERM specimens were obtained during vitrectomy from 28 diabetic patients with PDR and 30 non-diabetic control subjects. HGF and VEGF were determined by ELISA and c-Met expression by immunohistochemistry. Vitreal levels of both VEGF and HGF were higher in patients with PDR in comparison with the control group (p<0.0001). However, after correcting for total vitreous protein concentration, HGF (ng/mg of proteins) was lower in diabetic patients than in non-diabetic control subjects (p=0.02). No correlation was detected between the vitreal levels of HGF and VEGF. In addition, intravitreous VEGF but not HGF was found to be related to PDR activity. Both diabetic patients and non-diabetic patients in whom ERM had been excised presented higher HGF intravitreous levels. Finally, a significant expression of c-Met in ERM membranes were observed in both diabetic patients with PDR and in non-diabetic subjects. In conclusion, both HGF and VEGF increased, but were not related, in the vitreous fluid of diabetic patients with PDR. Our findings suggest that HGF is related to pathological conditions in which fibroproliferative processes or wound healing are involved rather than with angiogenesis itself.

Scatter factor/hepatocyte growth factor in brain tumor growth and angiogenesis

The multifunctional growth factor scatter factor/hepatocyte growth factor (SF/HGF) and its receptor tyrosine kinase c-Met have emerged as key determinants of brain tumor growth and angiogenesis. SF/HGF and c-Met are expressed in brain tumors, the expression levels frequently correlating with tumor grade, tumor blood vessel density, and poor prognosis. Overexpression of SF/HGF and/or c-Met in brain tumor cells enhances their tumorigenicity, tumor growth, and tumor-associated angiogenesis. Conversely, inhibition of SF/HGF and c-Met in experimental tumor xenografts leads to inhibition of tumor growth and tumor angiogenesis. SF/HGF is expressed and secreted mainly by tumor cells and acts on c-Met receptors that are expressed in tumor cells and vascular endothelial cells. Activation of c-Met leads to induction of proliferation, migration, and invasion and to inhibition of apoptosis in tumor cells as well as in tumor vascular endothelial cells. Activation of tumor endothelial c-Met also induces extracellular matrix degradation, tubule formation, and angiogenesis in vivo. SF/HGF induces brain tumor angiogenesis directly through only partly known mechanisms and indirectly by regulating other angiogenic pathways such as VEGF. Different approaches to inhibiting SF/HGF and c-Met have been recently developed. These include receptor antagonism with SF/HGF fragments such as NK4, SF/HGF, and c-Met expression inhibition with U1snRNA/ribozymes; competitive ligand binding with soluble Met receptors; neutralizing antibodies to SF/HGF; and small molecular tyrosine kinase inhibitors. Use of these inhibitors in experimental tumor models leads to inhibition of tumor growth and angiogenesis. In this review, we summarize current knowledge of how the SF/HGF:c-Met pathway contributes to brain tumor malignancy with a focus on glioma angiogenesis.

Prevention of neutrophil extravasation by hepatocyte growth factor leads to attenuations of tubular apoptosis and renal dysfunction in mouse ischemic kidneys

Ischemia and reperfusion (I/R) injuries occur in numerous organs under pathophysiological conditions. In this process, neutrophils play important roles in eliciting parenchymal injuries. Using a murine model of renal I/R, we show that hepatocyte growth factor (HGF) is a natural ligand that inhibits endothelial injuries and neutrophil extravasation. In mice after renal I/R, plasma HGF levels increased, along with c-Met/HGF receptor phosphorylation in the vascular endothelium. However, this c-Met activation was transient, associated with a decrease in endogenous HGF level, and followed by neutrophil infiltration and renal dysfunction. Suppression of endothelial c-Met phosphorylation by anti-HGF IgG led to rapid progressions of neutrophil extravasation, tubular apoptosis, and renal dysfunction. Inversely, enhancement of the c-Met activation by exogenous HGF blocked endothelial/tubular apoptotic injuries and acute renal failure. In this process, HGF prevented endothelial nuclear factor kappaB activation and inhibited induction of an adhesion molecule (ICAM-1), resulting in attenuated vascular edema and neutrophil infiltration. Thus, we conclude that 1) the HGF/c-Met system of endothelial cells confers an initial barrier to block neutrophil infiltration, and 2) transient and insufficient HGF production allows manifestation of postischemic renal failure. Our study provides a rationale for why HGF supplementation elicits therapeutic effects in ischemic kidneys.

Induction of angiogenesis and inhibition of apoptosis by hepatocyte growth factor effectively treats postischemic heart failure

BACKGROUND

Heart failure following myocardial infarction (MI) is a significant cause of morbidity and mortality and remains a difficult therapeutic challenge. Hepatocyte growth factor (HGF) is a potent angiogenic and anti-apoptotic protein whose receptor is upregulated following MI. This study was designed to investigate the ability of HGF to prevent heart failure in a rat model of experimental MI.

METHODS

The rats underwent direct intramyocardial injection with replication-deficient adenovirus encoding HGF (n = 7) or null virus as control (n = 7) 3 weeks following ligation of the left anterior descending coronary artery. Analysis of the following was performed 3 weeks after injection: cardiac function by pressure-volume conductance catheter measurements; LV wall thickness; angiogenesis by Von Willebrand's factor staining; and apoptosis by the TUNEL assay. The expression levels of HGF and the anti-apoptotic factor Bcl-2 were analyzed by Western blot.

RESULTS

Adeno-HGF-treated animals had greater preservation of maximum LV pressure (HGF 77 +/- 3 vs. control 64 +/- 5 mmHg, p < 0.05), maximum dP/dt (3024 +/- 266 vs. 1907 +/- 360 mmHg/sec, p < 0.05), maximum dV/dt (133 +/- 20 vs. 84 +/- 6 muL/sec, p < 0.05), and LV border zone wall thickness (1.98 +/- 0.06 vs. 1.53 +/- 0.07 mm, p < 0.005). Angiogenesis was enhanced (151 +/- 10.0 vs. 90 +/- 4.5 endothelial cells/hpf, p < 0.005) and apoptosis was reduced (3.9 +/- 0.3 vs. 8.2 +/- 0.5%, p < 0.005). Increased expression of HGF and Bcl-2 protein was observed in the Adeno-HGF-treated group.

CONCLUSIONS

Overexpression of HGF 3 weeks post-MI resulted in enhanced angiogenesis, reduced apoptosis, greater preservation of ventricular geometry, and preservation of cardiac contractile function. This technique may be useful to treat or prevent postinfarction heart failure.

Diagnostic validity of hepatocyte growth factor as marker for rejection in the follow-up of patients after heart transplantation

BACKGROUND

Hepatocyte growth factor (HGF) is a member of growth factor with a variety of known activities, including angiogenesis promotion and antiapoptotic action. It prevents acute graft-versus-host disease after bone marrow transplantation and prolongs allogenic graft survival in rats. The aim of the study was to investigate the relationship between serum HGF concentration and the grade of acute cellular rejection of heart transplant.

METHODS

We studied 68 male heart recipients. All of them received triple-drug immunosuppression: cyclosporine A, prednisone, and azathioprine or mycofenolate mofetil. All patients were without signs of heart failure. Blood samples were taken before elective ambulatory endomyocardial biopsy. Biopsy specimens were graded with the International Society for Heart and Lung Transplantation scale. Acute cellular rejection grade 3A and higher were considered as significant. Measurement of serum HGF was made by enzyme-linked immunosorbent assay.

RESULTS

We found a positive relationship between serum HGF levels and grade of cellular rejection. As an indicator for the detection of cell rejection processes, HGF with cutoff 2000 pg/ml seems to be useful.

CONCLUSIONS

The results of this study demonstrate that HGF can be useful as an indicator for heart graft cell rejection.

Intravitreous levels of hepatocyte growth factor/scatter factor and vascular cell adhesion molecule-1 in the vitreous fluid of diabetic patients with proliferative retinopathy

OBJECTIVE

Hepatocyte growth factor, also know as the scatter factor (HGF/SF) has been involved in the etiopathogenesis of proliferative diabetic retinopathy (PDR). To further explore this issue we have determine the intravitreous levels of HGF/SF taking into account the problems that could lead to misinterpretation of the results when the vitreous fluid is used to indirectly explore the events that are taking place in the retina. In addition, the relationship between HGF/SF and vascular cell adhesion molecule 1 (VCAM-1) was also investigated.

PATIENTS AND METHODS

Serum and vitreous samples were obtained during vitrectomy from 22 diabetic patients with PDR and 25 non-diabetic control subjects. Patients in whom intravitreous hemoglobin was detectable were excluded. A correction for plasma levels of either HGF/SF and VCAM-1 and intravitreal proteins was performed.

RESULTS

Vitreal levels of both HGF/SF and VCAM-1 were higher in patients with PDR in comparison with the control group (p<0.001 and p=0.003, respectively). However, after correcting for total vitreal proteins both HGF/SF and VCAM-1 (ng/mg of proteins) were lower in diabetic patients than in non-diabetic control subjects (p=0.03 and p<0.0001, respectively). No relationship between the vitreous levels of either HGF/SF or VCAM-1 with PDR activity was detected. Finally, a correlation between the vitreal levels of HGF/SF and VCAM-1 was observed in diabetic patients (r=0.61, p=0.005) but not in the control group.

CONCLUSION

Our results suggest that intraocular production of HGF/SF might be more important in mediating inflammatory and fibroproliferative processes rather than in angiogenesis itself.

Pulmonary expression of the hepatocyte growth factor receptor c-Met shifts from medial to intimal layer after cavopulmonary anastomosis

OBJECTIVE

Pulmonary arteriovenous malformations occur in up to 60% of patients after cavopulmonary anastomosis. We compared the effects of cavopulmonary anastomosis and pulmonary artery banding on lung gene expression in an ovine model to study the abnormal pulmonary vascular remodeling after the exclusion of inferior vena caval blood independent of reduced pulmonary blood flow. We previously demonstrated by contrast echocardiography that pulmonary arteriovenous malformations develop by 8 weeks after cavopulmonary anastomosis but not after pulmonary artery banding. Hepatocyte growth factor, a pleiotropic factor with morphogenic, mitogenic, and angiogenic activities, signals via its specific receptor c-Met to induce the antiapoptotic factor Bcl-2. In this study, we examined pulmonary artery expression of these factors and their potential role in pulmonary artery remodeling after cavopulmonary anastomosis and pulmonary artery banding.

METHODS

Eighteen lambs aged 35 to 45 days were placed into 3 groups: cavopulmonary anastomosis, pulmonary artery banding, and control (n = 6/group). In the cavopulmonary anastomosis group, the superior vena cava was anastomosed to the right pulmonary artery in an end-to-end fashion. In the pulmonary artery banding group, the left pulmonary artery was banded to reduce blood flow to 20% of control. The control group had a simple right pulmonary artery clamp for 30 minutes. Lung was harvested for Western blot, reverse transcriptase-polymerase chain reaction, and immunostaining at 2 weeks (n = 3/group) and 5 weeks (n = 3/group) after surgery.

RESULTS

The expression of c-Met mRNA after cavopulmonary anastomosis was increased by twofold compared with the control or pulmonary artery banding group. The total lung expression of c-Met by Western blot was also up regulated at 2 weeks (P <.05). However, total lung expression of hepatocyte growth factor and Bcl-2 by Western and reverse transcriptase-polymerase chain reaction was not different from the control and pulmonary artery banding groups at both 2 and 5 weeks after surgery. Immunohistochemical analysis revealed that c-Met expression was localized to the intimal layer of the pulmonary artery in the cavopulmonary anastomosis, while its expression in the control and pulmonary artery banding lungs was localized to the medial layer. Localization of Bcl-2 on the intimal layer in lambs with cavopulmonary anastomosis followed the same pattern as c-Met.

CONCLUSIONS

After cavopulmonary anastomosis, pulmonary artery expression of the hepatocyte growth factor receptor c-Met and one of its downstream effectors, Bcl-2, had increased in the intimal layer and decreased in the medial layer. Because the hepatocyte growth factor signaling promotes increased endothelial cell survival, it may have a role in pulmonary artery remodeling following cavopulmonary anastomosis. In addition, the change of c-Met expression in the medial layer after cavopulmonary anastomosis suggests a possible mechanism for the smooth muscle cell alteration related to abnormal angiogenesis.

Hepatocyte Growth Factor Protects against Hypoxia/Reoxygenation-induced Apoptosis in Endothelial Cells

Hypoxia/reoxygenation causes cellular injury and death associated with a number of pathophysiological conditions, including myocardial ischemia/reperfusion injury and stroke. The cell death pathways induced by hypoxia/reoxygenation and their underlying regulatory mechanisms remain poorly understood. Recent studies have shown that hypoxia/reoxygenation can induce Bax translocation and cytochrome c release. Using murine lung endothelial cells as a model, we found that the induction of apoptosis by hypoxia/reoxygenation involved the activation of both Bax-dependent and death receptor-mediated pathways. We demonstrated the activation of the death-inducing signal complex and Bid pathway after hypoxia/reoxygenation. Hepatocyte growth factor markedly inhibited hypoxia/reoxygenation-induced endothelial cell apoptosis. The cytoprotection afforded by hepatocyte growth factor was mediated in part by the stimulation of FLICE-like inhibiting protein expression, the attenuation of death-inducing signal complex formation, and the inhibition of Bid and Bax activation. Hepatocyte growth factor also prevented cell injury and death by increasing the expression of the antiapoptotic Bcl-XL protein. The inhibition of Bid/Bax-induced cell death by hepatocyte growth factor primarily involved p38 MAPK and in part Akt-dependent pathways but not ERK1/ERK2.