Effect of hepatocyte growth factor on early human haemopoietic cell development

Hepatocyte growth factor (HGF) stimulates cell proliferation, differentiation and migration by binding to its receptor, MET R. Whether the HGF/MET R axis plays an important regulatory role in human haemopoietic cell growth is an unresolved issue. To investigate this situation, we employed several complementary strategies including RT-PCR, FACS analysis, and mRNA perturbation with oligodeoxynucleotides (ODN). We found that very primitive, FACS sorted, CD34⁺ Kit⁺ marrow mononuclear cells (MNC) failed to express RT-PCR detectable MET R mRNA. In contrast, MET R expression was easily detectable by RT-PCR in marrow stroma fibroblasts, in cells isolated from BFU-E and CFU-GM colonies, and in unselected normal MNC. Subsequent FACS analysis revealed that MET R protein was detectable on ∼5% of the latter cells. HGF, at concentrations of 1–50 ng/ml, had no demonstrable effect on survival or cloning efficiency of normal CD34⁺ MNC in serum-free cultures. Antisense ODN mediated perturbation of MET R mRNA expression in normal CD34⁺ MNC, with FACS documented decline in protein expression, had no effect on the ability of these cells to give rise to haemopoietic colonies of any lineage. We also examined the biology of HGF/MET R expression in malignant haemopoietic cells. Using the strategies described above, we found that MET R mRNA was expressed in many human haemopoietic cell lines, and that the protein was expressed at high levels on HTLV transformed T lymphocytes. Wild-type CML and AML blast cells also expressed MET mRNA, and HGF was able to co-stimulate CFU-GM colony formation in ∼20% of cases studied. Therefore, although the HGF/MET R axis appears to be dispensable for normal haemopoietic cell growth, it may play a role in the growth of malignant haemopoietic progenitor cells.     

Serum hepatocyte growth factor as an index of extensive catabolism of patients awaiting liver transplantation

BACKGROUND: Whole body catabolism as the result of intrahepatic metabolic derangement is common in liver transplant candidates. However, individual nutritional assessment parameters lack sensitivity and specificity in determining energy status of these patients. Recently, serum hepatocyte growth factor (HGF) has been shown to reflect the recovery of hepatic energy metabolism after liver transplantation. AIMS: The relation between preoperative levels of serum HGF and metabolic variables was investigated to clarify the clinical value of measuring HGF in evaluations of the catabolism. PATIENTS/METHODS: Blood samples were obtained from 30 liver transplant recipients, and biopsy specimens were taken from each recipient's rectus muscle and the explanted liver. Preoperative serum concentration of HGF was determined. Whole body energy metabolism was assessed by measuring glycogen contents of biopsy specimens and plasma or serum levels of glucose, insulin, total ketone bodies, total carnitine, and amino acids. RESULTS: Serum HGF concentration was elevated in 22 of 30 patients and correlated with the Child-Pugh score. It showed a negative association with muscle glycogen content, and a positive correlation with serum levels of glucose, total carnitine, and total ketone bodies. Patients with elevated serum HGF concentrations had higher preoperative plasma levels of aromatic amino acids and branched chain amino acids, associated with lower branched chain to aromatic amino acid ratios. CONCLUSIONS: The elevated serum concentration of HGF in liver transplant candidates reflected inhibition of peripheral glucose storage, enhanced lipid oxidation, and increased peripheral release of branched chain amino acids, and thus extensive energy catabolism.     

Involvement of growth factor receptor-bound protein-2 in rat hepatocyte growth

Growth factor receptor-bound protein-2 (GRB-2) is a protein linking receptor tyrosine kinase and Sos ( Son of Sevenless gene; Ras GDP/GTP exchange protein), leading to activation of the Ras-mitogen-activated protein kinase (MAPK) cascade. So far, it remains unclear how GRB-2 plays a role in signal transduction pathways evoked by hepatotrophic factors. This study was attempted to evaluate the involvement of GRB-2 in signalling in rat hepatocyte growth. Using rat cultured hepatocytes stimulated by hepatotrophic factors and regenerating livers after partial hepatectomy (PH) we examined GRB-2-mediated linkage of hepatotrophic factor receptors to signal transducing molecules such as Sos or dynamin-II by immunoprecipitation and western blot analysis. In primary cultured hepatocytes stimulated with hepatocyte growth factor (HGF) or epidermal growth factor (EGF), GRB-2 linked HGF receptor or EGF receptor, respectively, to Sos which activated the mitogen-activated protein kinase (MAPK) cascade. In contrast, in primary cultured hepatocytes stimulated with insulin, GRB-2 linked insulin receptor substrate-1 (IRS-1) to dynamin-II as well as Sos. In the early phase after PH, GRB-2 activated the Ras-MAPK cascade by linking HGF receptor, IRS-1, or EGF receptor to Sos. In the late phase after PH, a complex of IRS-1-GRB-2 associated with dynamin-II, indicating that GRB-2 may transduce signals from IRS-1 to dynamin-II. We conclude that GRB-2 may play a role in transmitting signals from hepatotrophic factors to not only MAPK but also to other signalling pathways in hepatocyte growth.     

Gene expression profiles of drug-metabolizing enzymes and transporters with an overexpression of hepatocyte growth factor.

BACKGROUND: It is important to elucidate the precise mechanism of drug metabolism during hepatic regeneration. Although cytochromes P450 (CYPs) are well known to be down-regulated in growth-stimulated cells, the overall gene expression profile of drug metabolizing enzymes are still not fully understood during hepatic regeneration. In this study, we investigated the gene expression profiles of such enzymes with an overexpression of hepatocyte growth factor (HGF). METHODS: Gene expression profiles were obtained using the Affymetrix MOE430A GeneChip oligonucleotide microarray by comparing HGF transgenic mice and wild-type mice. RESULTS: HGF produced a general decrease in mice with the expression of CYP isoforms such as Cyp1a2, Cyp2b10, Cyp2c, Cyp2d9, Cyp3a11, Cyp4a10, and Cyp7a1. Some isoforms of alcohol dehydrogenase, aldehyde dehydrogenase, and carboxylesterase also decreased. In the phase II enzymes, some isoforms of glutathione S-transferase and UDP-glucuronosyl transferase showed a reduced expression, although the sulfotransferase did not. In phase III transporters, some organic anion transporter and organic cation transporters were down-regulated. Among the nuclear receptors that are known to regulate the drug-metabolizing enzymes, small heterodimer partner and constitutive androstane receptor were down-regulated with an HGF overexpression. The protein level and enzymatic activity of Cyp2c decreased with an HGF overexpression. We furthermore investigated the inducibility of Cyp2b10 with xenobiotic inducers. Although the basal expression of Cyp2b10 was repressed, the inducibility was not abolished with the HGF overexpression. CONCLUSIONS: HGF down-regulated not only CYPs but also some drug-metabolizing enzymes, transporters, and nuclear receptors. We thus have to take in our mind the low basal expression of drug metabolizing enzymes, when treating patients with a regenerative liver state.     

Hepatoma-derived growth factor is induced in liver regeneration

Aim:  Hepatoma-derived growth factor (HDGF) is a heparin-binding protein, which has been suggested to be involved in the development of kidneys, the cardiovascular system and the liver. We have shown that HDGF is highly expressed in parenchymal hepatocytes in the developing liver and promotes fetal hepatocyte proliferation. In the present study, we asked whether HDGF expression was related to liver regeneration.
Methods:  We examined the mRNA and protein expressions of HDGF in two liver regeneration models. In addition, cellular distribution of HDGF in the regenerating liver was investigated by immunohistochemistry.
Results:  In the carbon tetrachloride (CCl₄)-treated liver, HDGF expression was induced and the peak was detected at 24 h after the CCl₄ injection. HDGF expression was also enhanced in the hepatectomy model and the peak was detected at 12 h after surgery. The increased expression of HDGF protein was also confirmed by western blotting. Expression of the HDGF gene in the regenerating liver was dominantly detected in parenchymal hepatocytes.
Conclusion:  These findings showed that HDGF expression was induced in parenchymal hepatocytes before the DNA synthesis in the regenerating liver, suggesting the possible involvement of HDGF in liver regeneration as an autocrine factor.     

Treating liver cirrhosis in dogs with hepatocyte growth factor gene therapy via the hepatic artery

Background/purpose

Liver cirrhosis, an irreversible result of chronic liver disease, has had no effective therapy except liver transplantation. We previously reported successful therapy of liver cirrhosis in rats using the hepatocyte growth factor gene. We presently performed hepatocyte growth factor gene therapy in dogs with liver cirrhosis to examine the feasibility for clinical use.

Methods

Liver cirrhosis was established in beagles by administrating dimethylnitrosamine. Naked human hepatocyte growth factor gene or naked LacZ gene was injected repeatedly into livers via the hepatic artery using a porter catheter in dogs with cirrhosis.

Results

Human hepatocyte growth factor gene expression was detected in livers by immunohistochemical staining and an enzyme-linked immunosorbent assay. Serum liver function test results improved with hepatocyte growth factor gene therapy, which also inhibited hepatic transforming growth factor-β1expression and reversed fibrosis in cirrhotic liver, improving survival of the dogs.

Conclusion

As naked hepatocyte growth factor gene therapy via the hepatic artery proved simple, safe, and effective in larger animals with cirrhosis, this therapy may be clinically applicable.     

Gene expression profiles in liver cancer and normal liver tissues

AIM To describe a liver cancer = specific gene expression profile and to identify genes that showed alteredexpression between liver cancer tissues and their adjacent nearly normal tissues.METHODS The cDNA probes which were labeled with a-32P dATP were synthesized from total RNA ofliver cancer and adjacent normal tissues and hybridized separately to two identical Atlas human cancer eDNAexpression array membranes containing 588 known genes.RESULTS Autoradiographic results were analyzed by specific Atlas ImageTM (version 1. 0) software.Among the 588 genes analyzed, 18 genes were found up-regulated in cancer, including TFDP2, Aktl, E2F-3etc, and 25 genes were down-regulated in cancer, including TDGF1, BAK, LAR, etc. Expression levels ofgenes that associated with the regulation of cell proliferation, apoptosis, differentiation, cell-cellinteraction, invasion regulators and eytokines altered mostly.CONCLUSION The result obtained from Atlas microarray provides a comprehensive liver cancer-specificexpression profile. The results can lead to the identification of liver cancer-specific biomarkers and may behelpful in early diagnosis and dentifiction of target genes for designing rational therapeutic strategies.     

Hepatocyte growth factor: Molecular structure and implications for a central role in liver regeneration

Hepatocyte growth factor (HGF) is a most potent factor for mature parenchymal hepatocytes in primary culture and may act as a trigger for liver regeneration. We purified HGF from rat platelets to homogeneity and cloned both human and rat HGF cDNA. HGF is a heterodimer molecule composed of the 69 kDa alpha-subunit and the 34 kDa beta-subunit. HGF has no amino acid sequence homology with other known peptide growth factors and possesses the highest potential among known growth factors to stimulate proliferation of hepatocytes in primary culture. HGF is derived from a single chain precursor of 728 amino acid residues and the precursor is proteolytically processed to form a two-chain mature HGF. The alpha-subunit of HGF contains 4 kringle structures and HGF has a homology (38%) with plasmin. Biologically active recombinant human HGF could be expressed from COS-1 cells and CHO cells transfected with cloned cDNA. HGF activity and the HGF mRNA level are markedly increased in the liver following insult such as hepatitis, by the administration of hepatotoxins, ischaemia, physical damage and partial hepatectomy. Moreover, HGF mRNA is induced in the lung and kidney, in the presence of liver injury. In situ hybridization revealed that HGF-producing cells in liver are non-parenchymal liver cells, presumably Kupffer and sinusoidal endothelial cells. Therefore, HGF from neighbouring cells (Kupffer and sinsuoidal endothelial cells) and distal organs (lung and kidney) may function as a trigger for liver regeneration by both a paracrine mechanism and an endocrine mechanism. HGF has mitogenic activity for renal tubular epithelial cells, epidermal melanocytes and keratinocytes as well as mature hepatocytes, and has the potential to promote cell migration for some epithelial cells, including normal human keratinocytes. Since cell growth and cell motility are relevant to tissue repair and embryogenesis, HGF may well have important roles in tissue repair and embryogenesis as well as in liver regeneration.     

风湿性心脏病慢性心房颤动患者右心耳肝细胞生长因子及其受体的表达

目的观察风湿性心脏病慢性心房颤动(简称房颤)患者右心耳肝细胞生长因子(HGF)及受体(c-Met)表达的变化。方法将术中获取右心耳的27例风湿性瓣膜病患者分为2组,其中窦性心律(简称窦律)组8例,慢性房颤组19例,另选先天性心脏病患者8例(均为窦律)作为对照组,以β-肌动蛋白(β-actin)为内参照基因,采用实时荧光定量聚合酶链式反应(RealtimePCR)技术测定心房组织中HGF、c-MetmRNA的含量,用免疫组织化学方法评价HGF及c-Met的蛋白表达情况。结果与对照组和窦律组比较,慢性房颤组HGF表达显著下降(P<0.01)。而风心窦律组与对照组无差异。c-MetmRNA的表达三组无差异。结论慢性房颤患者心房组织HGF的表达显著降低,而其受体c-Met在房颤患者心房组织中未见明显变化。     

转化生长因子β受体-Ⅰ等在非酒精性脂肪性肝病患者肝组织中的表达

检测转化生长因子β受体Ⅰ（TGFβRⅠ）和血小板衍生生长因子（PDGF）-A、-B及其受体PDGFR-α、-β，观察其在各种类型的非酒精性脂肪性肝病（NAFLD）患者肝组织中的表达、分布和变化情况，以探讨其促进NAFLD发生脂肪性肝炎、脂肪性肝硬化的作用机制及临床意义。     

Elevated serum concentrations of activated hepatocyte growth factor activator in patients with multiple myeloma

Objectives: Hepatocyte growth factor (HGF) is a potential key factor in multiple myeloma. Conversion of pro‐HGF to its active form is a critical limiting step for its biological effects. We aimed to examine the levels of the most potent activator, the hepatocyte growth factor activator (HGFA), in serum and bone marrow plasma of patients with multiple myeloma. Methods: The activated form of HGFA was measured by an enzyme‐linked immunosorbent assay in serum (n = 49) and bone marrow plasma (n = 16) from multiple myeloma patients, and in serum from healthy controls (n = 24). Results: The median concentrations of activated HGFA in myeloma and control sera were 39.7 (range 6.2–450.0) and 17.6 ng/mL (range 4.8–280.6), respectively. The difference was statistically significant (P = 0.037). The median concentration of activated HGFA in bone marrow plasma was 6.1 ng/mL (range 3.5–30.0). Conclusion: We here show for the first time that the activated form of HGFA is present at high levels in serum and bone marrow of myeloma patients, thus providing a necessary prerequisite for the activation of HGF.     

Clinical significance of vascular endothelial growth factor and hepatocyte growth factor in multiple myeloma

Angiogenesis is a crucial process in the progression of multiple myeloma (MM). Vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) are multifunctional cytokines that potently stimulate angiogenesis including tumour neovascularization. Serum levels of VEGF and HGF were measured in 52 patients with MM by enzyme-linked immunosorbent assay (ELISA). Serum levels of VEGF and HGF were elevated in MM patients compared with healthy controls (VEGF: mean 0.31 ng/ml and 0.08 ng/ml respectively, P < 0.01; HGF: mean 2.17 ng/ml and 0.45 ng/ml, respectively, P < 0.001). In serial samples taken after chemotherapy, serum VEGF and HGF levels were correlated with M-protein levels. Serum levels of VEGF were higher in patients with extramedullary plasmacytomas than in patients without them (P < 0.05). They were also significantly higher in a group of patients who showed poor response to chemotherapy (P < 0.01). Serum levels of HGF were higher in patients with complications such as anaemia, hypercalcaemia and amyloidosis than in patients without these complications (P < 0.01, P < 0.05, P < 0.05 respectively). Both serum VEGF and HGF levels were significant predictors of mortality (P = 0.01, P = 0.02, respectively, log-rank test). The present study demonstrated that serum levels of VEGF and HGF are significantly elevated and dependent on the severity of MM, suggesting that measurement of VEGF and HGF may be useful for assessing disease progression and for predicting the response to chemotherapy in MM patients.     

酒精中毒患者血清中肝细胞再生因子水平的测定及其意义

探讨酒精中毒患者血清中肝细胞再生因子水平的变化及其意义。应用组织细胞培养法及同位素标记技术对 30例酒精中毒患者和 30例健康对照组血清中肝细胞再生因子水平进行测定。急性酒精中毒患者伴有肝功能异常者血清中肝细胞再生因子水平高于慢性酒精中毒 (P <0 0 5 ) ,并显著高于正常对照组 (P <0 0 1)。为估计酒精中毒患者的肝损伤程度提供参考价值。     

Association between serum hepatocyte growth factor and survival in untreated hepatocellular carcinoma

Background Hepatocellular carcinoma (HCC) is a common hepatic malignancy worldwide. Its nature of rapid growth results in a grave prognosis. Hepatocyte growth factor (HGF) is a mitogen for hepatocytes, responsible for their proliferation. The aim of the present study was to investigate the prognostic roles of serum HGF in untreated HCC patients.Methods Fifty-five patients with inoperable HCC were studied. The diagnosis of HCC was based on either liver histopathology or imaging evidence of a liver mass, together with elevated serum alpha-fetoprotein. Serum HGF levels of the patients, at the time of diagnosis, were compared to those of 28 healthy controls. All patients received only palliative treatments and were followed up until they died. Comparison of survival curves between patients with a serum HGF level of 1.0ng/ml or more and those with lower serum HGF was performed, using the log-rank test. Data values are expressed as means and SD.Results Fifty-one men and four women with inoperable HCC were recruited. The mean age was 54.15 ± 15.34 years. The serum HGF levels in the inoperable HCC patients were significantly higher than those in the controls (0.58 ± 0.43 vs 0.14 ± 0.04ng/ml; P < 0.001). The patients mean survival time was 5.28 ± 6.73 months (range, 0.1–33 months). Serum HGF levels exhibited a negative correlation with the survival time (P = 0.032). In addition, HCC patients with serum HGF levels of 1.0ng/ml or more had a shorter survival time than the other HCC patients (P = 0.0025).Conclusions Patients with inoperable HCC had higher levels of serum HGF than the healthy controls, and serum HGF was negatively correlated with the survival time. Serum HGF levels of 1.0ng/ml or more in HCC patients are suggestive of a grave prognosis, indicating that HGF plays important and active roles in the disease progression. The detailed mechanisms need to be further investigated.     

Hepatocyte apoptosis and hepatic expression of transforming growth factor-β1 mRNA during involution of hyperplastic rat liver induced by hepatocyte growth factor

Hepatocyte apoptosis occurs during involution of hyperplastic liver induced by administration of xenobiotic compounds in rats. With this hyperplasia and involution, hepatic transforming growth factor (TGF)-β₁ is reported to be expressed to stimulate hepatocyte apoptosis. In regenerating liver after partial resection showing no hyperplasia, such expression of TGF-β₁ is also seen. However, no hepatocyte apoptosis develops despite the high levels of TGF-β₁. When rats received an intravenous injection of human hepatocyte growth factor at 12 h intervals for 14 days, the hepatic DNA content was increased 12 h after the last injection to 140% of control. This DNA content was significantly decreased at 108 and 180 h after discontinuation of treatment. At 60 h after the last injection, the number of apoptotic bodies positive for nick end-labelling of DNA in hepatocytes was significantly greater in treated rats than in control rats. Hepatocyte apoptosis was also identified electron micrographically. Hepatic TGF-β₁ mRNA levels in treated rats were significantly lower than in control rats at 12 h and then gradually increased towards control levels. We conclude that hyperplastic liver induced in normal rats by hepatocyte growth factor regresses with hepatocyte apoptosis and suppressed hepatic TGF-β₁ mRNA levels.