Evidence for the identity of human scatter factor and human hepatocyte growth factor

Decreased Serum Hepatocyte Growth Factor (HGF) in Autistic Children with Severe Gastrointestinal Disease

Aim:

To assess serum Hepatocyte Growth Factor (HGF) levels in autistic children with severe gastrointestinal (GI) disease and to test the hypothesis that there is a relationship between GI pathology and HGF concentration.

Subjects and Methods:

Serum from 29 autistic children with chronic digestive disease (symptoms for a minimum of 6–12 months), most with ileo-colonic lymphoid nodular hyperplasia (LNH—markedly enlarged lymphoid nodules) and inflammation of the colorectum, small bowel and/or stomach), and 31 controls (11 age matched autistic children with no GI disease, 11 age matched non autistic children without GI disease and 9 age matched non autistic children with GI disease) were tested for HGF using ELISAs. HGF concentration of autistic children with GI disease was compared to GI disease severity.

Results:

Autistic children with GI disease had significantly lower serum levels of HGF compared to controls (autistic without GI disease; p = 0.0005, non autistic with no GI disease; p = 0.0001, and non autistic with GI disease; p = 0.001). Collectively, all autistic children had significantly lower HGF levels when compared to non autistic children (p < 0.0001). We did not find any relationship between severity of GI disease and HGF concentration in autistic children with GI disease.

Discussion:

These results suggest an association between HGF serum levels and the presence of GI disease in autistic children and explain a potential functional connection between the Met gene and autism. The concentration of serum HGF may be a useful biomarker for autistic children, especially those with severe GI disease.

Ligand-mediated dimerization of the Met receptor tyrosine kinase by the bacterial invasion protein InlB

The Listeria monocytogenes surface protein InlB mediates bacterial invasion into host cells by activating the human receptor tyrosine kinase Met. So far, it is unknown how InlB or the physiological Met ligand hepatocyte growth factor/scatter factor causes Met dimerization, which is considered a prerequisite for receptor activation. We determined two new structures of InlB, revealing a recurring, antiparallel, dimeric arrangement, in which the two protomers interact through the convex face of the leucine-rich repeat domain. The same contact is found in one structure of the InlB-Met complex. Mutations disrupting the interprotomeric contact of InlB reduced its ability to activate Met and downstream signaling. Conversely, stabilization of this crystal contact by two intermolecular disulfide bonds generates a constitutively dimeric InlB variant with exceptionally high signaling activity, which can stimulate cell motility and cell division. These data demonstrate that the signaling-competent InlB-Met complex assembles with 2:2 stoichiometry around a back-to-back InlB dimer, enabling the direct contact between the stalk region of two Met molecules.

Translational research to identify clinical applications of hepatocyte growth factor

Hepatocyte growth factor (HGF), originally purified from the plasma of patients with fulminant hepatic failure, has been shown to carry out various physiological functions. HGF not only stimulates liver regeneration, but also acts as an antiapoptotic factor in in vivo experimental models. Therefore, HGF is a promising therapeutic agent for the treatment of fatal liver diseases, including fulminant hepatic failure. After performing a number of preclinical tests, our group began an investigator-initiated registered phase I/II clinical trial of patients with fulminant hepatic failure to examine the safety and clinical efficacy of recombinant human HGF. In this article, we will discuss the basic research results as well as the translational research that underpins current attempts to use HGF in various clinical settings.

The lectin KM+ induces corneal epithelial wound healing in rabbits

Neutrophil influx is essential for corneal regeneration (Gan et al. 1999). KM+, a lectin from Artocarpus integrifolia, induces neutrophil migration (Santos-de-Oliveira et al. 1994). This study aims at investigating a possible effect of KM+ on corneal regeneration in rabbits. A 6.0-mm diameter area of debridement was created on the cornea of both eyes by mechanical scraping. The experimental eyes received drops of KM+ (2.5 microg/ml) every 2 h. The control eyes received buffer. The epithelial wounded areas of the lectin-treated and untreated eyes were stained with fluorescein, photographed and measured. The animals were killed 12 h (group 1, n = 5), 24 h (group 2, n = 10) and 48 h (group 3, n = 5) after the scraping. The corneas were analysed histologically (haematoxylin and eosin and immunostaining for proliferation cell nuclear antigen, p63, vascular endothelial growth factor, c-Met and laminin). No significant differences were found at the epithelial gap between treated and control eyes in the group 1. However, the number of neutrophils in the wounded area was significantly higher in treated eyes in this group. Three control and seven treated eyes were healed completely and only rare neutrophils persisted in the corneal stroma in group 2. No morphological distinction was observed between treated and control eyes in group 3. In treated corneas of group 2, there was an increase in immunostaining of factors involved in corneal healing compared to controls. Thus, topical application of KM+ may facilitate corneal epithelial wound healing in rabbits by means of a mechanism that involves increased influx of neutrophils into the wounded area induced by the lectin.

Overexpression of MACC1 leads to downstream activation of HGF/MET and potentiates metastasis and recurrence of colorectal cancer

Survival rates from colorectal cancer (CRC) differ dramatically according to the stage of the tumor at diagnosis, with survival rates of 90% for patients with stage I disease but only 49% for those with stage III cancer. Many serum and tumor markers have been identified but none has provided a significant improvement over tumor stage as a prognostic indicator for cancer recurrence for patients with stage II or III disease. Aberrant activation of the hepatocyte growth factor (HGF)/HGF receptor (MET) signaling pathway is associated with both malignant transformation and metastatic potential of CRC. MACC1 (metastasis-associated in colon cancer-1) is a newly discovered gene that regulates this signaling cascade. The significant correlation between overexpression of MACC1 in CRC and both malignant transformation and subsequent risk for metastases in stage II and III CRC indicates that MACC1 tumor typing may prove valuable for determining risk for CRC recurrence. MACC1 may also be an important therapeutic target for CRC treatment.

Immunopathogenesis of pelvic endometriosis: role of hepatocyte growth factor, macrophages and ovarian steroids

Endometriosis, a chronic disease characterized by endometrial tissue located outside the uterine cavity is associated with chronic pelvic pain and infertility. However, an in-depth understanding of the pathophysiology of endometriosis is still elusive. It is generally believed that besides ovarian steroid hormones, the growth of endometriosis can be regulated by innate immune system in pelvic microenvironment by their interaction with endometrial cells and immune cells. We conducted a series of studies in perspectives of pelvic inflammation that is triggered primarily by bacterial endotoxin (lipopolysaccharide) and is mediated by toll-like receptor 4 and showed their involvement in the development of pelvic endometriosis. As a cellular component of innate immune system, macrophages were found to play a central role in inducing pelvic inflammatory reaction. We further report here that peritoneal macrophages retain receptors encoding for estrogen and progesterone and ovarian steroids also participate in producing an inflammatory response in pelvic cavity and are involved in the growth of endometriosis either alone or in combination with hepatocyte growth factor (HGF). As a pleiotropic growth factor, HGF retains multifunctional role ometriosis. We describe here the individual and step-wise role of HGF, macrophages and ovarian steroid hormones and their orchestrated involvement in the immunopathogenesis of pelvic endometriosis.

Scatter Factors in renal disease: Dr. Jeckyll and Mr. Hyde?

The Scatter Factors are two homologous proteins, named Scatter Factor/Hepatocyte Growth Factor and Macrophage Stimulating Protein. Their receptors are the products of two oncogenes, Met and Ron, respectively. The Scatter Factors induce movement, stimulate proliferation, regulate apoptosis and are morphogenic, i.e. operate an integrated program that seems tailored to drive organ development and to regenerate injured tissues. On the other hand, Scatter Factors may be responsible for pathologic tissue remodeling, infiltration of inflammatory cells, and tumor growth and diffusion. The review describes the involvement of Scatter Factors in renal disease, including acute renal failure, glomerulonephritis, chronic fibrosing nephropathies, dialysis, renal transplantation and renal tumors, and discusses the double-faced role of Scatter Factors, that play either a protective or a pathogenic role.

Translational research on HGF: A phase I/II study of recombinant human HGF for the treatment of fulminant hepatic failure

Hepatocyte growth factor (HGF) is a potential therapeutic agent for fatal liver diseases, including fulminant hepatic failure (FHF). After performing a number of preclinical tests with recombinant human HGF (rh-HGF), we started a phase I/II study in September 2005 of patients with FHF or late-onset hepatic failure (LOHF), to examine the safety and clinical efficacy of rh-HGF. We first administered rh-HGF (0.6 mg/m(2)/day) for 13 days to a 67-year-old Japanese man with FHF. All data from this patient were reviewed by the independent data monitoring committee, and the safety of rh-HGF was recognized. Finally, a clinical trial of rh-HGF was approved to be continued. As of August 2007, we have administered rh-HGF to four patients with FHF or LOHF. All patients showed a moderate decrease in systolic blood pressure during rh-HGF administration, while the urinary excretion of albumin did not increase in all cases. In the first and third patients, hepatic failure gradually progressed, and they died 66 and 29 days, respectively, after encephalopathy occurred. The second and fourth patients are presently still alive. In conclusion, we started a clinical trial that examined the effects of rh-HGF in patients with FHF or LOHF, and in the four patients with FHF or LOHF enrolled in this study, repeated doses of rh-HGF did not produce any severe side effects.

The Met tyrosine kinase receptor in development and cancer

Met is a tyrosine kinase receptor, encoded by an oncogene, whose crucial role has been elucidated during the last two decades. The complex biological program triggered by Met has been dissected and its biological relevance in both physiology and pathology has been proven. Met supports a morphogenetic program, known as invasive growth, taking place both during embryogenesis and adulthood. In tumors Met is often aberrantly activated, giving rise to the pathological counterpart of the invasive growth program: cancer progression towards metastasis. Several approaches have been recently developed to interfere with the tumorigenic and metastatic processes triggered by Met.

Hepatocyte growth factor gene therapy for hypertension

Hepatocyte growth factor (HGF) has mitogenic, motogenic, and morphogenic biological activities as well as helps in regenerating various tissues. In cardiovascular organs, HGF was reported to have anti-apoptotic, anti-fibrotic, and vasodilating effects. HGF has close relationships with hypertension, arteriosclerosis, and heart failure. HGF enhances renal regeneration and suppresses the progression of hypertension. Intramuscular electroporation of the therapeutic gene is a simple, economic, and low toxic method compared with systemic administration of the purified proteins or peptides. We outline the technique of intramuscular electroporation of HGF gene as a remedy for hypertension.

Overexpression of NK2 promotes liver fibrosis in carbon tetrachloride-induced chronic liver injury

BACKGROUND/AIMS

Hepatocyte growth factor (HGF) inhibits liver fibrosis induced by carbon tetrachloride (CCl4) in animal models. NK2 is a natural splice variant of HGF, but its in vivo function remains to be elucidated. We investigated the in vivo effects of NK2 on CCl4-induced liver fibrosis.

METHODS

NK2 transgenic mice and wild-type (WT) mice were injected intraperitoneally with CCl4 twice a week. The extent of hepatic fibrosis was evaluated by Azan-Mallory staining. Expression levels of mRNAs of transforming growth factor-beta1 (TGF-beta1) and matrix metalloproteinase-13 (MMP-13) were examined by real-time polymerase chain reaction. The protein levels of alpha-smooth muscle actin (alpha-SMA), c-Met and its phosphorylation were determined by Western blot analysis.

RESULTS

Liver fibrosis was significantly more severe in NK2 transgenic mice than in WT mice. CCl4 administration increased the expression levels of TGF-beta1 mRNA and alpha-SMA protein, and decreased the expression of MMP-13 mRNA in livers of NK2 transgenic mice compared with those of WT mice. c-Met protein expression in the liver was compatible with the degree of fibrosis. As for c-Met activation, no difference was found between NK2 and WT livers.

CONCLUSION

Overexpression of NK2 acts as an antagonist of HGF and promotes liver fibrosis in CCl4-induced chronic liver injury.

Reassessing epithelial to mesenchymal transition as a prerequisite for carcinoma invasion and metastasis

For most carcinomas, progression toward malignancy is accompanied by loss of epithelial differentiation and a shift towards a mesenchymal phenotype. This process, referred to as epithelial to mesenchymal transition (EMT), exacerbates motility and invasiveness of many cell types and is often considered a prerequisite for tumor infiltration and metastasis. However, there are numerous examples of advanced carcinomas that adopt some mesenchymal features, yet retain characteristics of well-differentiated epithelial cells. We provide a review of these reports and describe mechanisms to explain the morphologic and molecular heterogeneity and plasticity of malignant carcinoma cells, including incomplete EMT, reversion to an epithelial phenotype, and collective migration. We suggest that these mechanisms can manifest in a series of independent and reversible steps and that EMT represents just one mechanism in the global metastatic carcinoma development process.

Evaluation of hepatocyte growth factor as a sensitive marker for early detection of acute renal allograft rejection

BACKGROUND

It has been shown that hepatocyte growth factor (HGF), besides its well-established hepatotrophic effect in liver regeneration, is involved in the regeneration of the kidney after injury. In the present study we investigated whether HGF can serve as a marker for detection of acute rejection in the early posttransplantation period.

METHODS

HGF levels were determined in pre- and posttransplant sera (up to day 21) of 26 recipients with biopsy-proven acute rejection, 30 recipients with acute tubular necrosis (ATN), and 32 recipients without posttransplant complications.

RESULTS

Although no association was found between pretransplant HGF and death-censored functional graft survival, receiver operating characteristic (ROC) curves demonstrated that HGF measured during the entire posttransplant study period, and especially on days 3 to 5, was a good marker for differentiating recipients who subsequently developed acute rejection from recipients with an uncomplicated course (P<0.0001, specificity 87%, sensitivity 84%). HGF measured from day 3 until day 21 posttransplantation, and especially on days 7 to 9, was also a sensitive marker for differentiating recipients with ATN from recipients with an uncomplicated course (P<0.0001). If considered in combination with sCD30, the diagnostic value of HGF was further improved. While 73% of samples from patients with impending rejection were positive for both HGF and sCD30, 94% of samples from nonrejecting patients were double-negative and none of the samples from this group fell into the double-positive category (P<0.0001).

CONCLUSIONS

Our data suggest that HGF measured during the early posttransplant period might be a useful parameter for early detection of acute renal allograft rejection.

c-Met is essential for wound healing in the skin

Wound healing of the skin is a crucial regenerative process in adult mammals. We examined wound healing in conditional mutant mice, in which the c-Met gene that encodes the receptor of hepatocyte growth factor/scatter factor was mutated in the epidermis by cre recombinase. c-Met-deficient keratinocytes were unable to contribute to the reepithelialization of skin wounds. In conditional c-Met mutant mice, wound closure was slightly attenuated, but occurred exclusively by a few (5%) keratinocytes that had escaped recombination. This demonstrates that the wound process selected and amplified residual cells that express a functional c-Met receptor. We also cultured primary keratinocytes from the skin of conditional c-Met mutant mice and examined them in scratch wound assays. Again, closure of scratch wounds occurred by the few remaining c-Met-positive cells. Our data show that c-Met signaling not only controls cell growth and migration during embryogenesis but is also essential for the generation of the hyperproliferative epithelium in skin wounds, and thus for a fundamental regenerative process in the adult.

Adenoviral vector expressing hepatocyte growth factor promotes liver regeneration by preoperative injection: the advantages of performing selective injection to the remnant lobe

BACKGROUND

In a cirrhotic liver, the regenerative ability is impaired and liver failure may occur after a hepatectomy. Hepatocyte growth factor (HGF) stimulates liver regeneration and adenoviral vector expressing hepatocyte growth factor (AdHGF) allows hepatocyte growth factor (HGF) to be persistently expressed. The aim of this study is to evaluate the benefits of the selective and preoperative injection of AdHGF to the remnant lobes to regenerate the liver.

METHODS

A 70% partial hepatectomy was performed in dimethylnitrosamine-induced cirrhotic rats with a preoperative injection of AdHGF, adenoviral vector carrying beta-galactosidase (AdLacZ), or phosphate-buffered saline (PBS). The morphologic, histologic, and biochemical changes in the remnant liver and survival rates were then assessed.

RESULTS

Portal injection with clamping the portal branches of the resected lobes for 5 min made it possible to effectively transduce the adenoviral vector into the remnant lobes. On day 7 after hepatectomy, the survival rates were 87% in the AdHGF group, 53% in the AdLacZ group, and 40% in the PBS group (P < .05). The ratio of the remnant liver weight/body weight (%) was 2.0 +/- 0.1 in the AdHGF group, 1.5 +/- 0.3 in the AdLacZ group, and 1.6 +/- 0.04 in the PBS group (P < .01). The 5-bromo-2'-deoxyuridine labeling index significantly increased in the AdHGF group on day 1, and the fibrous status significantly decreased in the AdHGF group on day 7 after hepatectomy.

CONCLUSIONS

Preoperatively, the selective injection of AdHGF into the remnant lobes may be an effective treatment prior to a major hepatectomy in a cirrhotic liver.

Inhibitory effect of c-Met mutants on the formation of branching tubules by a porcine aortic endothelial cell line

The association of hepatocyte growth factor (HGF) with its high-affinity receptor (c-Met) has been shown to induce mitogenesis, motogenesis and morphogenesis in a variety of cell types. Various point mutations in c-Met have been identified in hereditary and sporadic papillary renal carcinomas as well as in other carcinomas. In the present study, we examined the effects of c-Met point mutations on the morphology of a porcine aortic endothelial (PAE) cell line. When cultured in three-dimensional collagen gel, PAE cells formed branching tubule structures, and HGF treatment caused breakdown of the structures and induced a scattered morphology. The exogenous expression of c-Met point mutants inhibited the formation of tubules. HGF treatment induced the formation of tubules by PAE cells expressing some c-Met mutants, but it induced the scattering of PAE cells expressing other c-Met mutants. The presence of a low concentration of a mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK) inhibitor cancelled the inhibitory effect of the c-Met point mutations on the formation of tubules. These results suggest that c-Met point mutations affect the extracellular signal-regulated kinase (ERK) signaling required for the formation of tubules by PAE cells, and HGF binding changes the conformation of c-Met mutants, leading to the different signals required for formation of tubules and cell scattering.

Combined measurement of hepatocyte growth factor and carcinoembryonic antigen as a prognostic marker for patients with dukes a and B colorectal cancer: results of a five-year study

PURPOSE

There is no marker capable of differentiating patients with Dukes A and B colorectal cancer with aggressive diseases from those with indolent diseases. We evaluated the results of five years of actuarial survival data to determine whether serial monitoring of serum hepatocyte growth factor could provide prognostic information on these patients.

METHODS

Blood samples of 147 colorectal cancer patients were obtained and the serum concentration of hepatocyte growth factor was measured.

RESULTS

Elevated serum hepatocyte growth factor levels were associated with stage progression. Although the overall positive rate of hepatocyte growth factor in the patients was the same as that of the carcinoembryonic antigen, the positive rate of hepatocyte growth factor in the Dukes A patients was two times higher than that of the carcinoembryonic antigen, and nearly 40 percent of the carcinoembryonic antigen-negative patients had a positive serum hepatocyte growth factor in the Dukes A and B classification. In this subgroup, patients with positive serum hepatocyte growth factor or carcinoembryonic antigen levels had a poorer prognosis, whereas positive serum hepatocyte growth factor level after surgery could predict disease recurrence.

CONCLUSIONS

A combination of serum hepatocyte growth factor and carcinoembryonic antigen tests might be useful for selecting patients with aggressive diseases in Dukes A and B classification.

Gene transfer of hepatocyte growth factor by electroporation reduces bleomycin-induced lung fibrosis

Abnormal alveolar wound repair contributes to the development of pulmonary fibrosis after lung injury. Hepatocyte growth factor (HGF) is a potent mitogenic factor for alveolar epithelial cells and may therefore improve alveolar epithelial repair in vitro and in vivo. We hypothesized that HGF could increase alveolar epithelial repair in vitro and improve pulmonary fibrosis in vivo. Alveolar wound repair in vitro was determined using an epithelial wound repair model with HGF-transfected A549 alveolar epithelial cells. Electroporation-mediated, nonviral gene transfer of HGF in vivo was performed 7 days after bleomycin-induced lung injury in the rat. Alveolar epithelial repair in vitro was increased after transfection of wounded epithelial monolayers with a plasmid encoding human HGF, pCikhHGF [human HGF (hHGF) gene expressed from the cytomegalovirus (CMV) immediate-early promoter and enhancer] compared with medium control. Electroporation-mediated in vivo HGF gene transfer using pCikhHGF 7 days after intratracheal bleomycin reduced pulmonary fibrosis as assessed by histology and hydroxyproline determination 14 days after bleomycin compared with controls treated with the same vector not containing the HGF sequence (pCik). Lung epithelial cell proliferation was increased and apoptosis reduced in hHGF-treated lungs compared with controls, suggesting increased alveolar epithelial repair in vivo. In addition, profibrotic transforming growth factor-beta1 (TGF-beta1) was decreased in hHGF-treated lungs, indicating an involvement of TGF-beta1 in hHGF-induced reduction of lung fibrosis. In conclusion, electroporation-mediated gene transfer of hHGF decreases bleomycin-induced pulmonary fibrosis, possibly by increasing alveolar epithelial cell proliferation and reducing apoptosis, resulting in improved alveolar wound repair.

The molecular and clinical impact of hepatocyte growth factor, its receptor, activators, and inhibitors in wound healing

Wound healing involves a number of cellular and molecular events, many of which are controlled by soluble growth factors. In the process of healing, hepatocyte growth factor, a cytokine known to act as mitogen, motogen, and morphogen, has been postulated to play multiple roles during several stages of this complex biological process. Produced primarily by stromal fibroblasts, hepatocyte growth factor regulates angiogenesis, vascular permeability, cell migration, matrix deposition and degradation, and other biological processes. The current article discusses recent progress in understanding the multiple roles played by this growth factor in tissue repair.

Combination gene therapy of HGF and truncated type II TGF-beta receptor for rat liver cirrhosis after partial hepatectomy

BACKGROUND

In a cirrhotic liver, the regenerative ability and specific functions are impaired; a hepatic resection increases the possibility of postoperative liver failure. Hepatocyte growth factor (HGF) stimulates liver regeneration, accelerates restoration of hepatic function, and improves fibrosis. A truncated type II transforming growth factor-beta receptor (TbetaTR), which specifically inhibits TGF-beta signaling as a dominant-negative receptor, appears to prevent the progression of liver fibrosis. We demonstrated the therapeutic efficacy of adenovirus-mediated HGF and TbetaTR gene transduction after partial hepatectomy for liver cirrhosis.

METHODS

Rats were treated with dimethylnitrosamine for 3 weeks, and they all had severe cirrhosis. After partial hepatectomy (10%), we injected adenovirus expressing bacterial beta-galactosidase (AdLacZ), adenovirus expressing a truncated type II TGF-beta receptor (AdTbetaTR), adenovirus expressing hepatocyte growth factor (AdHGF), or AdTbetaTR + AdHGF into the portal vein, which was followed by an additional 2-week dimethylnitrosamine treatment.

RESULTS

On histologic examination, fibrotic tissue had decreased in the livers of the AdTbetaTR + AdHGF-treated rats compared with rats that were treated by AdLacZ, AdTbetaTR alone, and AdHGF alone. Liver function, which included serum levels of alanine aminotransferase, improved significantly in AdTbetaTR + AdHGF-treated rats compared with all other groups. The number of hepatocytes that were positive for proliferating-cell nuclear antigen was greater (P < .05) in AdHGF alone and AdTbetaTR + AdHGF-treated rat livers than in AdLacZ- and AdTbetaTR-treated rats. All AdTbetaTR + AdHGF-treated rats survived >60 days, and AdTbetaTR + AdHGF treatment markedly improved the survival rate after a partial hepatectomy.

CONCLUSION

Our results suggest that the combination of HGF and TbetaTR gene therapy may increase the possibility of hepatectomy in a cirrhotic liver by improving fibrosis, hepatic function, and hepatocyte regeneration.

Consistent Expression of HGF and c-met in the Perinatal Lung

BACKGROUND

Hepatocyte growth factor (HGF), an epithelial cell mitogen, has been shown to participate in normal lung development and in regeneration after lung injury. In human preterm infants, lower pulmonary HGF has been associated with more severe respiratory disease.

OBJECTIVES

We studied the protein expression of HGF and its receptor c-met during the perinatal period in the human lung.

METHODS

Immunohistochemistry for HGF and c-met was performed on lung tissues from autopsies of 4 fetuses, 5 preterm infants, 5 term infants, and 4 infants with bronchopulmonary dysplasia.

RESULTS

Immunohistochemistry for HGF showed staining in all cases in mesenchymal cells (fibroblasts and cartilage cells). Additional staining was found in bronchial and distal airway epithelium. Immunohistochemistry for c-met showed staining in bronchial and distal airway epithelium, and in most cases in neutrophils.

CONCLUSIONS

The consistent expression of HGF and c-met during the perinatal period supports a physiological role for HGF in human lung development.

Perioperative allogeneic blood transfusion, the related cytokine response and long-term survival after potentially curative resection of colorectal cancer

AIMS

It is still debated whether perioperative blood transfusion alters the incidence of disease recurrence or otherwise affects the prognosis after curative resection of malignant tumours. We conducted a prospective observational study of patients with colorectal cancer to provide data on the effect of blood transfusion and the related perioperative cytokine response on long-term prognosis.

MATERIALS AND METHODS

Perioperative blood samples were obtained from 117 patients with colorectal cancer undergoing potentially curative resection. Factors associated with perioperative blood transfusion were assessed, and their relationship with early postoperative systemic responses of tumour growth factors and long-term prognosis were evaluated.

RESULTS

Independent factors associated with perioperative blood transfusion were preoperative anaemia, operative blood loss and the development of postoperative infectious complication. The patients receiving transfusions were subdivided according to the independent factors. Group A comprised 19 patients who received blood transfusions because of preoperative anaemia and Group B comprised 16 patients who received blood transfusions because of excessive operative blood loss. Group B patients showed exaggerated postoperative systemic induction of interleukin (IL)-6 and IL-6-triggered tumour growth factors, such as hepatocyte growth factor and vascular cell adhesion molecule-1. Intraoperative blood transfusion under intense surgical stress was associated with poor prognosis, whereas preoperative blood transfusion for correcting anaemia or intraoperative blood transfusion under less invasive surgery was not associated with survival. Multivariate analysis using the Cox proportional hazards method showed that a significant independent risk was demonstrated for blood transfusion, T stage, lymph-node metastasis and perioperative peak levels of IL-6.

CONCLUSION

Blood transfusion and intense surgical stress might synergistically affect the long-term prognosis after curative resection of colorectal cancer. Postoperative exaggerated systemic inductions of IL-6 may indicate the critical situation that could lead to disease recurrence.

Secretory expression and characterization of a recombinant-deleted variant of human hepatocyte growth factor in Pichia pastoris

AIM

To study the secretory expression of human hepatocyte growth factor (hdHGF) gene in Pichia pastoris.

METHODS

The full-length gene of human cDNA encoding the deleted variant of hdHGF was cloned by RT-PCR and overlapping-fragment PCR technique using mRNA of human placenta as a template. The cloned hdHGF cDNA was inserted into the Escherichia coli-yeast shuttle vector of pPIC9. The constructed plasmid, pPIC9-hdHGF, was transformed into the GS115 cells of the methylotrophic yeast, P pastoris, using a chemical method. The Mut(+ ) transformants were screened to obtain high-expression strains by the test and analysis of expressed products of shake-flask culture. A secretory form of rhdHGF was made with the aid of the leader peptide sequence of Saccharomyces cerevisiae alpha-factor.

RESULTS

The expressed products, which showed a band of molecular mass of about 80 ku, were observed on 15% SDS-PAGE and identified by Western blotting and N-terminal amino acid sequencing. In the high cell density culture of 5 L fermentor by fed-batch culture protocol, the cell biomass was reached at approximately 135 g (DCW)/L. The productivity of secreted total supernant protein concentration attained a high-level expression of more than 8.0 g/L and the ratio of rhdHGF band area was about 12.3% of the total band area scanned by SDS-PAGE analysis, which estimated that the product of rhdHGF was 500-900 mg/L.

CONCLUSION

The P pastoris system represents an attractive tool of generating large quantities of hdHGF for both research and industrial purposes.

Structural basis of hepatocyte growth factor/scatter factor and MET signalling

The polypeptide growth factor, hepatocyte growth factor/scatter factor (HGF/SF), shares the multidomain structure and proteolytic mechanism of activation of plasminogen and other complex serine proteinases. HGF/SF, however, has no enzymatic activity. Instead, it controls the growth, morphogenesis, or migration of epithelial, endothelial, and muscle progenitor cells through the receptor tyrosine kinase MET. Using small-angle x-ray scattering and cryo-electron microscopy, we show that conversion of pro(single-chain)HGF/SF into the active two-chain form is associated with a major structural transition from a compact, closed conformation to an elongated, open one. We also report the structure of a complex between two-chain HGF/SF and the MET ectodomain (MET928) with 1:1 stoichiometry in which the N-terminal and first kringle domain of HGF/SF contact the face of the seven-blade beta-propeller domain of MET harboring the loops connecting the beta-strands b-c and d-a, whereas the C-terminal serine proteinase homology domain binds the opposite "b" face. Finally, we describe a complex with 2:2 stoichiometry between two-chain HGF/SF and a truncated form of the MET ectodomain (MET567), which is assembled around the dimerization interface seen in the crystal structure of the NK1 fragment of HGF/SF and displays the features of a functional, signaling unit. The study shows how the proteolytic mechanism of activation of the complex proteinases has been adapted to cell signaling in vertebrate organisms, offers a description of monomeric and dimeric ligand-receptor complexes, and provides a foundation to the structural basis of HGF/SF-MET signaling.

Dispersal of epithelial cancer cell colonies by lysophosphatidic acid (LPA)

We describe a model system in which cancer cell colonies disperse into single, highly migratory cells in response to lysophosphatidic acid (LPA). Though LPA is known to stimulate chemotaxis and chemokinesis, a colony dispersal effect has not been reported, to our knowledge. Cancer colony dispersal by LPA is comprised of an ordered sequence of events: (1) stimulation of membrane ruffling and formation of lamellipodia, (2) dissolution of adherens junctions, (3) single cell migration in a mesenchymal-like morphology we term "ginkgo-leaf." The net result is dispersal of carcinoma cells from a compact colony. We analyzed these three steps using live-cell imaging and computer-assisted quantification and measured the following parameters: onset of lamellipodia formation, lamellipodia velocity, colony dispersal, trans-epithelial resistance, migrating cell number and speed. Because hepatocyte growth factor (HGF) was described as an epithelial scatter factor, we compared it to LPA in our system and found that HGF has no epithelial colony dispersal properties and that this effect is strictly related to LPA. Given its striking similarity to tumor cell budding observed in patients, we propose that LPA-colony dispersal may provide a cellular mechanism underlying cancer invasion and as such deserves further studies.

Regulation of testicular function by cell-to-cell interaction

Cell-to-cell interactions in the testis play important roles in regulating testicular function. Investigating the mechanism of such interactions is essential to elucidate the cause of spermatogenic dysfunction and to create a new treatment. (Reprod Med Biol 2006; 5: 9-17).

Molecular control of liver development

Recent studies using animal models have elucidated a growing number of evolutionarily conserved genes and pathways that control liver development from the embryonic endoderm. It is increasingly clear that the genetic programs active in embryogenesis are often deregulated or reactivated in disease, cancer, and tissue repair. Understanding the molecular control of liver development should impact diagnosis and treatment of pediatric and adult liver diseases and aid in efforts to differentiate liver tissue in vitro for stem cell-based therapies.

Mast cell and neutrophil peptidases attack an inactivation segment in hepatocyte growth factor to generate NK4-like antagonists

Hepatocyte growth factor (HGF) is a plasminogen-like protein with an alpha chain linked to a trypsin-like beta chain without peptidase activity. The interaction of HGF with c-met, a receptor tyrosine kinase expressed by many cells, is important in cell growth, migration, and formation of endothelial and epithelial tubes. Stimulation of c-met requires two-chain, disulfide-linked HGF. Portions of an alpha chain containing an N-terminal segment and four kringle domains (NK4) antagonize HGF activity. Until now, no physiological pathway for generating NK4 was known. Here we show that chymases, which are chymotryptic peptidases secreted by mast cells, hydrolyze HGF, thereby abolishing scatter factor activity while generating an NK4-like antagonist of HGF scatter factor activity. Thus, chymase interferes with HGF directly by destroying active protein and indirectly by generating an antagonist. The site of hydrolysis, Leu480, lies in the alpha chain on the N-terminal side of the cysteine linking the alpha and beta chains. This site appears to be specific for HGF because chymase does not hydrolyze other plasminogen-like proteins, such as macrophage-stimulating protein and plasminogen itself. Mast cell/neutrophil cathepsin G and neutrophil elastase generate similar fragments of HGF by cleaving near the chymase site. Mast cell and neutrophil peptidases are secreted during tissue injury, infection, ischemia, and allergic inflammation, where they may oppose HGF effects on epithelial repair. Thus, HGF possesses an "inactivation segment" that serves as an Achilles' heel attacked by inflammatory proteases. This work reveals a potential physiological pathway for inactivation of HGF and generation of NK4-like antagonists.

Overexpression of ADAM9 enhances growth factor-mediated recycling of E-cadherin in human colon cancer cell line HT29 cells

Growth factor-mediated stimulation of epithelial cells induces the disassembly of E-cadherin-mediated cell-cell adhesion. We found that overexpression of a disintegrin and metalloprotease 9 (ADAM9) enhanced growth factor-mediated induction of endocytosis and dynamic recycling of E-cadherin in HT29 human colon cancer cells. In addition, ubiquitination and degradation of E-cadherin were reduced in these cells. ADAM9 constitutively interacted with E-cadherin, and the two proteins co-localized at the plasma membrane of HT29 cells. Administration of a metalloprotease inhibitor or overexpression of an ADAM9 mutant lacking metalloprotease activity attenuated growth factor-dependent endocytosis and recycling of E-cadherin as well as scattering of HT29 cells. These results suggest that the metalloprotease activity of ADAM9 mediates growth factor-induced endocytosis and dynamic recycling of E-cadherin and prevents E-cadherin degradation.

Arginine-specific gingipains from Porphyromonas gingivalis stimulate production of hepatocyte growth factor (scatter factor) through protease-activated receptors in human gingival fibroblasts in culture

Cystein proteinases (gingipains) from Porphyromonas gingivalis cleave a broad range of in-host proteins and are considered to be key virulence factors in the onset and development of adult periodontitis and host defense evasion. In periodontitis, an inflammatory disease triggered by bacterial infection, the production of hepatocyte growth factor (HGF) is induced not only by various factors derived from the host, such as inflammatory cytokines, but also by bacterial components. In this study we examined the possible enhanced production of HGF produced by human gingival fibroblasts upon stimulation with gingipains. Arginine-specific gingipain (Rgp) caused a marked production of HGF into the supernatant, the induction of HGF expression on the cell surface, and the up-regulation of HGF mRNA expression in a dose-dependent and an enzymatic activity-dependent manner. Because it has been reported that Rgp activated protease-activated receptors (PARs), we examined whether the induction of HGF triggered by Rgps on human gingival fibroblasts occurred through PARs. An RNA interference assay targeted to PAR-1 and PAR-2 mRNA revealed that gingipains-induced secretion of HGF was significantly inhibited by RNA interference targeted to PAR-1 and PAR-2. In addition, the Rgps-mediated HGF induction was completely inhibited by the inhibition of phospholipase C and was clearly inhibited by RNA interference targeted to p65, which is an NF-kappaB component. These results suggest that Rgps activated human gingival fibroblasts to secrete HGF in the inflamed sites and the mechanism(s) involved may actively participate in both inflammatory and reparative processes in periodontal diseases.

Generation of inhibitory DNA aptamers against human hepatocyte growth factor

Hepatocyte growth factor (HGF), a multifunctional cytokine, can act on many cell types. It is involved in cancer growth and metastasis by enhancing the motility of cancer cells and stimulating angiogenesis. The development of effective inhibitors for HGF is an important issue in cancer therapy. In this study, we isolated DNA aptamers against human HGF using the systematic evolution of ligands by exponential enrichment method. The selected DNA aptamers had a highly conserved consensus sequence, and could be divided into two major classes (classes I and II). The consensus motif of classes I and II might contribute to the formation of a hairpin loop structure and a G-quartet structure, respectively. These DNA aptamers bound to human HGF with high affinity and specificity. The dissociation constants of typical aptamers H38-15 and H38-21, representative of the two classes, were calculated to be approximately 20 nM. H38-15 and H38-21 inhibited the biological activities of HGF including the stimulation of scattering, migration, and invasion of pancreatic cancer KP-3 cells. Furthermore, both aptamers inhibited HGF-induced tube formation by human umbilical vein endothelial cells. These results suggested that the isolated DNA aptamers will be useful as therapeutic and diagnostic reagents for cancers.

Hepatocyte growth factor delivered by ultrasound-mediated destruction of microbubbles induces proliferation of cardiomyocytes and amelioration of left ventricular contractile function in Doxorubicin-induced cardiomyopathy

At present, there is no curative strategy for advanced cardiomyopathy except for cardiac transplantation, which is not easily performed, mainly due to a shortage of donors. It has been reported that myocardial progenitor cells exist even in the postnatal heart, suggesting that myocardial progenitor cells could proliferate under some situations and might improve cardiac function in cardiomyopathy-induced hearts. In this study, recombinant human hepatocyte growth factor (rhHGF) was delivered using ultrasound-mediated destruction of microbubbles (UMDM) into the cardiomyopathy-induced heart by doxorubicin (20 mg/kg). Intravenous injection of rhHGF (IV-rhHGF) alone or UMDM alone failed to improve the morphology or the function of the cardiomyopathy-induced heart, but (IV-rhHGF + UMDM) treatment significantly improved the heart morphologically and functionally, and repetitive treatments of (IV-rhHGF + UMDM) enhanced the effects. The number of bromodeoxy-uridine-positive cardiomyocytes significantly increased in the (IV-rhHGF + UMDM)-treated hearts compared with the untreated hearts. Moreover, Sca-1+ myocardial progenitor cells express c-Met, a receptor for HGF. These results suggest that (IV-rhHGF + UMDM) treatment could morphologically and functionally improve the heart in the case of doxorubicin-induced cardiomyopathy through the proliferation of the myocardial progenitor cells.

Expression of serine protease SNC19/matriptase and its inhibitor hepatocyte growth factor activator inhibitor type 1 in normal and malignant tissues of gastrointestinal tract

AIM: To provide the expression profile of serine protease SNC19/matriptase and its inhibitor hepatocyte growth factor activator inhibitor type 1 (HAI-1) in normal and malignant tissues of gastrointestinal tract at mRNA level for further study on their correlations with tumor progression and metastasis.

METHODS: Total RNAs were prepared from 37 samples of colorectal cancer tissues, 40 samples of gastric cancer tissues, and their adjacent normal tissues. The expression of SNC19/matriptase and HAI-1 in these samples was detected by real-time fluorescent quantitative PCR using glyceraldehyde-3-phosphate dehydrogenase as internal standard, and the clinical significance for the correlation with clinicopathological parameters was evaluated.

RESULTS: In gastric cancer tissues the expression of HAI-1 and SNC19/matriptase was significantly lower than that in the corresponding adjacent normal tissues (Z = -3.280, P = 0.006; Z = -4.651, P = 0.000). HAI-1:SNC19/matriptase ratio showed no difference between normal and malignant tissues (P>0.05). Analysis of clinicopathological parameters showed decreased expression of HAI-1 and HAI-1:SNC19/matriptase ratio associated with stage III/IV gastric tumors as compared to stage I/II ones (Z = -2.140, P = 0.031; Z = -2.155, P = 0.031), and with lymph node-positive gastric cancer tissues as compared to lymph node-negative ones (Z = -2.081, P = 0.036; Z = -2.686, P = 0.006). The expression of SNC19/matriptase had no relationship with stages and lymph node metastasis (P>0.05). The expression of HAI-1 and HAI-1:SNC19/matriptase ratio increased in well-differentiated gastric cancer tissues, but there was no statistical significance (P>0.05). The difference of SNC19/matriptase expression was not significant in gastric cancer tissues of different histological differentiation status (P>0.05). In colorectal cancer tissues, the expression of HAI-1 and SNC19/matriptase was also markedly lower than that in their adjacent normal tissues (Z = -3.100, P = 0.002; Z = -2.731, P = 0.006), whereas HAI-1:SNC19/matriptase ratio showed no difference. Decreased expression of HAI-1 was associated with increased invasive depth and lymph node metastasis, but there was no statistical significance (P>0.05). The difference of SNC19/matriptase expression and HAI-1:SNC19/matriptase ratio was not significant in different stages and different lymph node metastasis status (P>0.05). The expression of SNC19/matriptase, HAI-1 or HAI-1:SNC19/matriptase ratio showed no difference in colorectal cancer tissues of different histological differentiation status (P>0.05).

CONCLUSION: The expressions of SNC19/matriptase and its inhibitor HAI-1 are decreased in gastrointestinal cancer tissues compared to their normal counterparts, and the decreased expression of HAI-1 may correlate with invasion and lymph node metastasis. The possible mechanisms involved need to be further investigated.

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.

Expression of hepatocyte growth factor/scatter factor receptor in IUGR fetuses' placentas: an immunohistochemical analysis

OBJECTIVE

We aimed to evaluate the expression sta tus of c-met, receptor for the hepatocyte growth factor (HGF), in the placentas of intrauterine growth retardation (IUGR) fetuses.

MATERIALS AND METHODS

Placentas were obtained during delivery from both third trimester normal and IUGR complicated pregnancies. Ultrasonographic estimation of fetal birth weight has been done and placentas of those under the fifth percentile for their gestational ages were enrolled in the study group. Eighteen fetuses with IUGR and 6 uncomplicated pregnancies were subjected to the study. Histological sections from placentas were immunohistochemically evaluated for the expression status of c-met.

RESULTS

Seventeen of the eighteen patients (94.4%) in the study group were found to have overexpression of the c-met while this figure was only 16.7% (1/6) in the control group (p < 0.0001). There was a strong statistically significant difference between the two groups regarding degree of c-met expression.

CONCLUSION

Our present findings suggest that c-met is an important cell membrane receptor in human placenta. Deregulation of the interaction between HGF and its receptor c-met during placentation may be the cause responsible for the growth retardation of the fetus due to the impaired placental functions.

Transplantation of cultured salivary gland cells into an atrophic salivary gland

Patients with dry mouth have been treated with salivary substitutes and/or medications such as pilocarpine or cevimeline hydrochloride. These treatments temporarily relieve their symptoms and induce salivation from residual tissue. However, no treatment is available for the purpose of regenerating an atrophic gland. In this study, the feasibility of a cell transplantation therapy for the atrophic submandibular glands was investigated in rats. Further, the potential of cell differentiation into a useful phenotype was assessed by immunohistochemistry together with cell tracking with the fluorescent dye PKH 26. Rat submandibular glands were excised, and the salivary gland epithelial cells were cultured for 3 weeks with 3T3 cells as a feeder layer. Ductal ligation of the submandibular gland was employed to generate an atrophic gland. One week after the operation, the ligation was removed, and the cultured cells labeled with PKH 26 were injected into the atrophic submandibular glands. As a control, the cultured cells were also injected into normal submandibular glands. Two weeks after cell transplantation, the transplanted cells were detectable in both the experimental and control groups. The cells were clustered in the connective tissue between the lobules. Four weeks after transplantation, the labeled cells were detectable in the experimental group but not in the control group. In the atrophic glands, the scattered transplanted cells were observed over a broad area of the gland but localized mainly around the acini and ductal region. Immunostaining results showed a possible involvement of the transplanted cells in ductal regeneration, while neither myoepithelial nor acinar differentiations were observed within the 4 weeks since transplantation. This study demonstrated that cell transplantation to the salivary gland is feasible, and that the transplanted cells were selectively attracted to and remained in the damaged area without affecting normal tissue.

Proliferation and invasion: plasticity in tumor cells

Invasive and proliferative phenotypes are fundamental components of malignant disease, yet basic questions persist about whether tumor cells can express both phenotypes simultaneously and, if so, what are their properties. Suitable in vitro models that allow characterization of cells that are purely invasive are limited because proliferation is required for cell maintenance. Here, we describe glioblastoma cells that are highly invasive in response to hepatocyte growth factor/scatter factor (HGF/SF). From this cell population, we selected subclones that were highly proliferative or displayed both invasive and proliferative phenotypes. The biological activities of invasion, migration, urokinase-type plasminogen activation, and branching morphogenesis exclusively partitioned with the highly invasive cells, whereas the highly proliferative subcloned cells uniquely displayed anchorage independent growth in soft agar and were highly tumorigenic as xenografts in immune-compromised mice. In response to HGF/SF, the highly invasive cells signal through the MAPK pathway, whereas the selection of the highly proliferative cells coselected for signaling through Myc. Moreover, in subcloned cells displaying both invasive and proliferative phenotypes, both signaling pathways are activated by HGF/SF. These results show how the mitogen-activated protein kinase and Myc pathways can cooperate to confer both invasive and proliferative phenotypes on tumor cells and provide a system for studying how transitions between invasion and proliferation can contribute to malignant progression.

Matrix metalloproteinase-1 up-regulation by hepatocyte growth factor in human dermal fibroblasts via ERK signaling pathway involves Ets1 and Fli1

In this study, we clarified the molecular mechanism(s) underlying the regulation of matrix metalloproteinase (MMP)-1 gene by hepatocyte growth factor (HGF) in cultured human dermal fibroblasts. HGF induced MMP-1 protein as well as mRNA at a transcriptional level via extracellular signal-regulated kinase (ERK) signaling pathway. The region in the MMP-1 promoter mediating the inducible responsiveness to HGF, defined by the transient transfection analysis of the serial 5′ deletion constructs, contained an Ets binding site. Mutation of this Ets binding site abrogated the HGF-inducible promoter activity. Ets1 up-regulated the expression of MMP-1 promoter activity, whereas Fli1 had antagonistic effects on them. After HGF treatment, the protein level and the binding activity of Ets1 was increased and those of Fli1 was decreased, which were canceled by PD98059. These results suggest that HGF up-regulates MMP-1 expression via ERK signaling pathway through the balance of Ets1 and Fli1, which may be a novel mechanism of regulating MMP-1 gene expression.

Regulation of hepatocyte growth factor by basal and stimulated macrophages in women with endometriosis

BACKGROUND

The different macromolecules as secreted by macrophages in the pelvic environment are believed to enhance the growth of endometriosis. However, the possible mediator that stimulates macrophages for the production of different growth factors is not well described. Therefore, we investigated the possible production of hepatocyte growth factor (HGF) by the basal and lipopolysaccharide (LPS)-stimulated macrophages derived from women with or without endometriosis.

METHODS

Using primary culture and 4-well chamber slides, adherent macrophages immunoreactive to CD68 were isolated from the peritoneal fluid (PF) of 20 infertile women with endometriosis and 12 women without endometriosis. The proliferation of basal and LPS-treated macrophages was investigated by the dimethylthiazole tetrazolioum bromide (MTT) assay. The production of HGF in the culture media of basal and LPS-stimulated macrophages was examined by enzyme-linked immunosorbent assay. The expression of mRNA for HGF and its receptor, c-Met, in the macrophages was investigated by RT-PCR. The effect of HGF on the growth of endometrial cells and macrophages was analysed by bromodeoxyuridine (BrdU) incorporation.

RESULTS

A >100% increase in the proliferation of peritoneal macrophages derived from women with endometriosis, and particularly of those harbouring dominant red lesions, was observed after treatment with LPS (P<0.05). A 4- and 3-fold increase in the production of HGF was observed by the LPS-treated macrophages derived from women with stage I-II endometriosis and stage III-IV endometriosis, respectively, when compared with non-LPS-treated macrophages (P<0.001). At the transcriptional level, we found a 5-fold increase in HGF mRNA expression in LPS-treated macrophages versus basal macrophages in women with endometriosis (P<0.001). The BrdU incorporation study indicates that 10-100 ng/ml of HGF enhanced the growth of endometrial epithelial cells, stroma and macrophages (approximately 50% increase) derived from women with endometriosis (all P<0.05).

CONCLUSION

LPS could be an inflammatory mediator of macrophage stimulation in the pelvic microenvironment. Besides mesenchymal cells, HGF is also produced by peritoneal macrophages and is possibly involved in the growth of endometriosis.

Therapeutic targeting of receptor tyrosine kinases in lung cancer

Lung cancer is a difficult illness with a poor overall survival. Even though combination strategies with chemotherapy, radiation therapy and surgery have all been utilised, the overall outcome for this disease continues to be relatively disappointing. In order to make a difference in the treatment of lung cancer, novel therapeutics will have to be developed. Through basic biological studies, a number of receptor tyrosine kinases have been implicated in the pathogenesis and progression of lung cancer. In this review, the authors summarise the mechanisms of several major receptor tyrosine kinases in lung cancer, especially epidermal growth factor receptor, Her2/neu, MET, vascular endothelial growth factor and KIT. The biology associated with these receptors is described, and the various novel therapeutic inhibitory strategies that are ongoing in preclinical and clinical studies for lung cancer are detailed. Through understanding of receptor tyrosine kinases and the utilisation of specific inhibitors, it is hopeful that a dramatic impact will be made on the biology and therapy for lung cancer.

Modulation of hepatocyte growth factor induction in human skin fibroblasts by retinoic acid

Topical treatment of skin with all-trans-retinoic acid (ATRA), the major biologically active form of vitamin A, results in hyperproliferation of basal keratinocytes, leading to an accelerated turnover of epidermis cells and thickening of the epidermis, probably via induction of production of paracrine growth factors for keratinocytes in epidermal suprabasal keratinocytes and/or dermal fibroblasts. Since hepatocyte growth factor (HGF) is a factor mitogenic to epidermal keratinocytes secreted from dermal fibroblasts, the effect of ATRA on basal and induced HGF production in human dermal fibroblasts in culture was examined. ATRA alone did not induce HGF production, but it significantly enhanced HGF production induced by the cAMP-elevating agent cholera toxin or the membrane-permeable cAMP analog 8-bromo-cAMP. Cholera toxin-induced activation of cAMP responsive element (CRE)-binding protein (CREB) was enhanced by pretreating cells with ATRA for 24 h. In contrast, HGF production induced by epidermal growth factor (EGF) or phorbol 12-myristate 13-acetate (PMA) was potently inhibited by ATRA. These modulatory effects of ATRA were different from the effects of transforming growth factor-beta1 (TGF-beta) and dexamethasone, both of which inhibited HGF production induced by all of the four inducers. Up-regulation of HGF gene expression by cholera toxin and EGF was also enhanced and inhibited, respectively, by ATRA. Both 9-cis-retinoic acid (9-cis-RA) and 13-cis-retinoic acid (13-cis-RA), which are stereo-isomers of ATRA, showed a modulatory effect on HGF induction similar to that of ATRA. These results suggest that ATRA augments the induction of HGF production caused by increased intracellular cAMP.

Met receptor dynamics and signalling

The receptor for hepatocyte growth factor (HGF), Met, controls a programme of invasive growth that combines proliferation with various moto- and morphogenetic processes. This process is important for development and organ regeneration, but dysregulation in transformed tissues can contribute to cancer progression and metastasis. Acute stimulation of tissue culture cells with HGF leads to Met downregulation via degradation through an endocytic mechanism that also requires proteasome activity. Perturbation of Met trafficking on the endocytic pathway, either at the level of the internalisation step or during sorting at the early endosome, leads to altered signalling outputs. Ubiquitination of Met through the E3-ligase Cbl is required for receptor downregulation, and a mutant receptor defective in Cbl binding is able to transform cells. We discuss the hypothesis that some naturally occurring Met mutants implicated in cancer may transform cells owing to defects in their trafficking along the endosomal degradation pathway.

Effects of hepatocyte growth factor on the expression of type I collagen and matrix metalloproteinase-1 in normal and scleroderma dermal fibroblasts

We investigated the direct effect of hepatocyte growth factor (HGF) on the expression of type I collagen in normal and scleroderma dermal fibroblasts, and analyzed the mechanisms underlying the effect in vitro. HGF did not change the protein expression of type I procollagen in the medium of normal human fibroblasts, whereas it reduced the expression in scleroderma fibroblasts. But mRNA levels and the promoter activity of alpha2(I) collagen gene were not significantly affected by HGF in either of the cells. On the other hand, matrix metalloproteinase-1 expression or activity was increased by HGF in both cells, but HGF had stronger effects in scleroderma fibroblasts than normal fibroblasts. Scleroderma fibroblasts overexpressed c-met protein, the receptor for HGF. The overexpression in scleroderma fibroblasts was abolished by the addition of antisense transforming growth factor (TGF)-beta1 oligonucleotide. Our study indicated that HGF may reduce type I collagen accumulation only in scleroderma fibroblasts by enhancing collagenolysis activity, probably because of the overexpression of c-met because of autocrine TGF-beta signaling. Thus, further investigation of the effects of HGF on collagen metabolism may contribute to the treatment of fibrosis in scleroderma.

RNAi technology and lentiviral delivery as a powerful tool to suppress Tpr-Met-mediated tumorigenesis

Tpr-Met, the oncogenic counterpart of the Met receptor, has been detected in gastric cancers, as well as in precursor lesions and in the adjacent normal gastric mucosa. This has prompted the suggestion that Tpr-Met may predispose to the development of gastric tumors. Given the sequence specificity of RNA interference, oncogenes activated by point mutation or rearrangements can be targeted while spearing the product of the wild-type allele. In this work, we report specific suppression of Tpr-Met expression and inhibition of Tpr-Met-mediated transformation and tumorigenesis by means of a short interfering RNA (siRNA) directed toward the Tpr-Met junction (anti-TM2). When delivered by a lentiviral vector, anti-TM2 siRNA was effective also in mouse embryonal fibroblasts or epithelial cells expressing high levels of Tpr-Met. Our results suggest that lentiviral-mediated delivery of anti-TM2 siRNA may be developed into a powerful tool to treat Tpr-Met-positive cancers.