Regional mapping of the human hepatocyte growth factor (HGF)-scatter factor gene to chromosome 7q21.1

Research Progress on the Regulation Mechanism of Key Signal Pathways Affecting the Prognosis of Glioma

As is known to all, glioma, a global difficult problem, has a high malignant degree, high recurrence rate and poor prognosis. We analyzed and summarized signal pathway of the Hippo/YAP, PI3K/AKT/mTOR, miRNA, WNT/β-catenin, Notch, Hedgehog, TGF-β, TCS/mTORC1 signal pathway, JAK/STAT signal pathway, MAPK signaling pathway, the relationship between BBB and signal pathways and the mechanism of key enzymes in glioma. It is concluded that Yap1 inhibitor may become an effective target for the treatment of glioma in the near future through efforts of generation after generation. Inhibiting PI3K/Akt/mTOR, Shh, Wnt/β-Catenin, and HIF-1α can reduce the migration ability and drug resistance of tumor cells to improve the prognosis of glioma. The analysis shows that Notch1 and Sox2 have a positive feedback regulation mechanism, and Notch4 predicts the malignant degree of glioma. In this way, notch cannot only be treated for glioma stem cells in clinic, but also be used as an evaluation index to evaluate the prognosis, and provide an exploratory attempt for the direction of glioma treatment. MiRNA plays an important role in diagnosis, and in the treatment of glioma, VPS25, KCNQ1OT1, KB-1460A1.5, and CKAP4 are promising prognostic indicators and a potential therapeutic targets for glioma, meanwhile, Rheb is also a potent activator of Signaling cross-talk etc. It is believed that these studies will help us to have a deeper understanding of glioma, so that we will find new and better treatment schemes to gradually conquer the problem of glioma.

Research Progress on the Regulation Mechanism of Key Signal Pathways Affecting the Prognosis of Glioma

As is known to all, glioma, a global difficult problem, has a high malignant degree, high recurrence rate and poor prognosis. We analyzed and summarized signal pathway of the Hippo/YAP, PI3K/AKT/mTOR, miRNA, WNT/β-catenin, Notch, Hedgehog, TGF-β, TCS/mTORC1 signal pathway, JAK/STAT signal pathway, MAPK signaling pathway, the relationship between BBB and signal pathways and the mechanism of key enzymes in glioma. It is concluded that Yap1 inhibitor may become an effective target for the treatment of glioma in the near future through efforts of generation after generation. Inhibiting PI3K/Akt/mTOR, Shh, Wnt/β-Catenin, and HIF-1α can reduce the migration ability and drug resistance of tumor cells to improve the prognosis of glioma. The analysis shows that Notch1 and Sox2 have a positive feedback regulation mechanism, and Notch4 predicts the malignant degree of glioma. In this way, notch cannot only be treated for glioma stem cells in clinic, but also be used as an evaluation index to evaluate the prognosis, and provide an exploratory attempt for the direction of glioma treatment. MiRNA plays an important role in diagnosis, and in the treatment of glioma, VPS25, KCNQ1OT1, KB-1460A1.5, and CKAP4 are promising prognostic indicators and a potential therapeutic targets for glioma, meanwhile, Rheb is also a potent activator of Signaling cross-talk etc. It is believed that these studies will help us to have a deeper understanding of glioma, so that we will find new and better treatment schemes to gradually conquer the problem of glioma.

Expression of the Hepatocyte Growth Factor and C-Met in Colon Cancer: Correlation with Clinicopathological Features and Overall Survival

Aim and Background

The hepatocyte growth factor (HGF)/c-Met signaling system has been implicated in the development and progression of colon cancer, but the relationship between the expression of HGF or c-MET and clinicopathologic features remains controversial. In the study, we analyzed the expression of HGF and c-Met in colon cancer and assessed the influence of the expression of this growth factor and its receptor on clinical and histological parameters and patient survival.

Methods and Study Design

We investigated the mRNA expression of HGF and c-Met with real-time PCR in 90 unselected colon carcinomas and the corresponding normal mucosa. Furthermore, HGF and c-Met protein expression was investigated with immunohistochemistry in all the samples.

Results

The mRNA and protein expression levels of HGF and c-Met were significantly higher in colon cancer than in matched normal mucosa. The protein level in most of the cases investigated was correlated with the mRNA level. Overexpression of HGF and c-Met, at both protein and mRNA levels, was correlated with depth of invasion, lymph node metastases and overall AJCC stage. According to univariate analysis, the mean survival time was shorter in the HGF-positive and c-Met-positive groups. Multivariate Cox analysis showed that high M stage and the expression of c-Met independently had a negative impact on overall survival.

Conclusions

The HGF/c-Met signaling pathway may be involved in the pathogenesis and progression of colon cancer. C-Met overexpression can be used as a useful parameter to evaluate the prognosis of colon cancer.

SV40 replication in human mesothelial cells induces HGF/Met receptor activation: a model for viral-related carcinogenesis of human malignant mesothelioma

Recent studies suggested that simian virus 40 (SV40) may cause malignant mesothelioma, although the pathogenic mechanism is unclear. We found that in SV40-positive malignant mesothelioma cells, the hepatocyte growth factor (HGF) receptor (Met) was activated. In human mesothelial cells (HMC) transfected with full-length SV40 DNA (SV40-HMC), Met receptor activation was associated with S-phase entry, acquisition of a fibroblastoid morphology, and the assembly of viral particles. Coculture experiments revealed the ability of SV40-HMC to infect permissive monkey cells (CV-1), HMC, and murine BNL CL cells. Cocultured human and murine SV40-positive cells expressed HGF, showed Met tyrosine phosphorylation and S-phase entry, and acquired a spindle-shaped morphology (spBNL), whereas CV-1 cells were lysed. Cocultured HMC inherited from SV40-HMC the infectivity, as they induced lysis in cocultured CV-1 cells. Treatment with suramin or HGF-blocking antibodies inhibited Met tyrosine phosphorylation in all large T antigen (Tag)-positive cells and reverted the spindle-shaped morphology of spBNL. This finding indicated that Met activation and subsequent biological effects were mediated by an autocrine HGF circuit. This, in turn, was causally related to Tag expression, being induced by transfection with the SV40 early region alone. Our findings suggest that when SV40 infects HMC it causes Met activation via an autocrine loop. Furthermore, SV40 replicates in HMC and infects the adjacent HMC, inducing an HGF-dependent Met activation and cell-cycle progression into S phase. This may explain how a limited number of SV40-positive cells may be sufficient to direct noninfected HMC toward malignant transformation.

The hepatocyte growth factor/Met pathway in development, tumorigenesis, and B-cell differentiation

This article summarizes the structure, signal transduction and physiologic functions of the HGF/Met pathway, as well as its role in tumor growth, invasion, and metastasis. Moreover, it highlights recent studies indicating a role for the HGF/Met pathway in antigen-specific B-cell development and B-cell neoplasia.

Numerical chromosomal changes in DNA hypodiploid solid tumors: restricted loss and gain of certain chromosomes

BACKGROUND

DNA hypodiploidy is a unique and rare finding associated with aggressive behavior in solid tumors. Identifying the chromosomal changes underlying this feature may provide important information on the development and progression of these neoplasms.

METHODS

Fluorescence in situ hybridization analysis using alpha-satellite probes for nine autosomes and the two sex chromosomes was performed on interphase cells from 27 solid tumors which had been shown to be DNA hypodiploid by flow cytometry. The chromosomal abnormalities were correlated with the DNA index and tumor subtypes.

RESULTS

The data show mutually exclusive loss of certain chromosomes and compensatory gain of other chromosomes in different tumors. The net loss was slightly more than the net gain for the chromosomes tested. Polysomy of chromosome 7 and monosomy of chromosomes 17, X and loss Y were found in most tumors. Significant differential loss of chromosomes 6,10, and 12 among DNA hypodiploid breast, kidney and lung carcinomas was noted.

CONCLUSIONS

Our study shows (i) gain of chromosome 7 and loss chromosome 17 in most DNA hypodiploid tumors, (ii) specific chromosomal loss was noted in breast and renal cell carcinomas, and (iii) that different mechanisms for DNA hypodiploid and hyperdiploid development may exist.

Hepatocyte growth factor and c-MET in benign and malignant peripheral nerve sheath tumors

Hepatocyte growth factor (HGF), secreted by mesenchymal cells, has pleiotropic biological activities on several cell types. HGF and its receptor, the c-met proto-oncogene product (c-MET) have been implicated in the genesis and progression of several carcinomas and sarcomas. It has been suggested that MET/HGF autocrine signaling may contribute to tumorigenesis in sarcomas. HGF has been recently found to be a mitogen for rat Schwann cells and to be present in neurofibromas in NF1 patients. In this investigation, we assessed the immunoreactive patterns of HGF and MET in benign and malignant peripheral nerve sheath tumors (PNST) using archival formalin-fixed tissue. The standard avidin-biotin-peroxidase method was used. All benign tumors were negative with HGF. Eight cases of MPNST were positive with both HGF and MET. In some malignant PNST, positivity with both ligand and the receptor may be indicative of an autocrine mediated signal transduction and may implicate HGF/MET in tumor progression. Immunoreactivity with MET was strikingly greater in MPNST in contrast to benign PNST; this finding may prove to be helpful in distinguishing some histologically low-grade MPNST from cellular and atypical benign PNST.

Chromosomal localization of rat hepatocyte growth factor (Hgf) and HGF receptor (Met) and characterization of HGF receptor cDNA

The Met protooncogene encodes the tyrosine kinase receptor for the hepatocyte growth factor (HGF), a potent mitogen for hepatocytes and other epithelial cells produced by mesenchymal cells. Many of the studies on the physiologic and neoplastic growth of the liver, as well as other organs, have been performed in the rat. Therefore, chromosomal mapping of the rat Hgf gene and the gene of its receptor is of particular value. To achieve this, a probe of the coding part of rat HGF cDNA was used to isolate four genomic probes from a lambda phage rat genomic library. These probes were used to map the Hgf gene to Chromosome (Chr) 4q12 by the FISH technique. To obtain a probe for the mapping of the HGF receptor/Met gene, we cloned the complete coding region of the rat HGF receptor mRNA. Complementary DNA (cDNA) was synthesized with reverse transcriptase from total RNA for use as a template for the PCR. The two PCR primers were designed based on human and mouse sequences and were located in the flanking regions of the open reading frame of the HGF receptor mRNA. Amplification resulted in a band of an estimated size of 4.1 kb, which was cloned and sequenced. The nucleotide sequence showed about 93% and 85% homology compared with mouse and human HGF receptor sequences, respectively. A full-length probe of the coding part of the cDNA was used to map the rat HGF receptor/Met gene to Chr 4q21 by the FISH technique. Therefore, the rat Hgf and HGF receptor/Met genes are located relatively close to each other, in a way similar to humans but not mice.

Control of invasive growth by hepatocyte growth factor (HGF) and related scatter factors

Hepatocyte growth factor (HGF) is the prototype of a family of structurally related soluble molecules, named scatter factors (SFs). These control a complex genetic programme leading to cell-dissociation, migration in the extracellular matrix, growth, acquisition of polarity and tubule formation. This programme is pivotal during the embryonic development of epithelial and some mesodermal-derived tissues. In the adult HGF sustains cell survival and regeneration. A structurally related molecule, originally identified as macrophage stimulating protein (MSP), triggers the same complex genetic programme in epithelial and neural cells. The receptors for HGF and MSP are the tyrosine kinases encoded by the homologous genes MET and RON. As a distinctive feature, these receptors act via a two-phosphotyrosine docking site, capable of concomitant activation of multiple intracellular transducers and signalling pathways. In a number of malignant tumours, MET and RON constitutively sustain the genetic programme of scattering, leading to invasive growth and metastatic phenotype. Four MET-related receptors have been recently identified (the SEX protein family). These molecules are predominantly expressed during development and are likely to mediate repelling cues between cells of different type.

Identification of functional domains in the hepatocyte growth factor and its receptor by molecular engineering

Hepatocyte growth factor/scatter factor (HGF/SF) is a heparin-binding polypeptide which shares structural domains with enzymes of the blood clotting cascade. HGF/SF is secreted by cells of mesodermal origin and has powerful mitogenic, motogenic and morphogenic activity on epithelial and endothelial cells. HGF/SF is produced as a biologically inactive single-chain precursor (pro-HGF/SF) most of which is sequestered on the cell surface or bound to the extracellular matrix. Maturation into the active alpha beta heterodimer results from proteolytic cleavage by a urokinase-type protease, which acts as a pro-HGF/SF convertase. The primary determinant for receptor binding appears to be located within the alpha-chain. The interaction of the alpha-chain with the receptor is sufficient for the activation of the signal cascade involved in the motility response. However, the complete HGF/SF protein seems to be required to elicit a mitogenic response. HGF/SF binds with high affinity to a transmembrane receptor, p190MET, encoded by the MET proto-oncogene. p190MET is the prototype of a distinct subfamily of heterodimeric tyrosine kinases, including the putative receptors Ron and Sea. The mature form of p190MET is a heterodimer of two disulfide-linked subunits (alpha and beta). The alpha-subunit is extracellular and heavily glycosylated. The beta-subunit consists of an extracellular portion involved in ligand binding, a membrane spanning segment, and a cytoplasmic tyrosine kinase domain. Both subunits derive from glycosylation and proteolytic cleavage of a common precursor of 170 kDa. In polarized epithelial cells the HGF/SF receptor is selectively exposed in the basolateral plasmalemma, where it is associated with detergent-insoluble components. Two Met isoforms, carrying an intact ligand binding domain but lacking the kinase domain due to truncation of the beta-subunit, arise from alternative post-transcriptional processing of the mature form. One truncated form is soluble and released from the cells. HGF/SF binding triggers tyrosine autophosphorylation of the receptor beta-subunit. Autophosphorylation on the major phosphorylation site Y1235 upregulates the kinase activity of the receptor, increasing the Vmax of the phosphotransfer reaction. Negative regulation of the kinase activity occurs through phosphorylation of a unique serine residue (S985) located in the juxtamembrane domain of the receptor. This phosphorylation is triggered by two distinct pathways involving either protein kinase C activation or increase in intracellular Ca2+ concentration. Upon ligand binding, the HGF/SF receptor recruits and activates several cytoplasmic effectors, including phosphatidylinositol 3-kinase (PI 3-K), phospholipase C-gamma (PLC-gamma), pp60c-Src, a tyrosine phosphatase, and a Ras-guanine nucleotide exchanger.(ABSTRACT TRUNCATED AT 400 WORDS)

Deletion 7q22 in uterine leiomyoma. A cytogenetic review

The cytogenetic patterns of uterine leiomyomas have been extensively investigated, and cases characterized by specific clonal changes have been documented in detail. In these tumors one of the cytogenetic changes frequently observed has been a del(7), particularly del(7)(q22), usually as a sole anomaly. This is confirmed by our experience and by reports in the literature. The fact that del(7) is one of the most common abnormalities in leiomyoma raises the question of its role in tumor development. The main purpose of this review is to analyze the above aspect and to interpret its possible meaning. Our findings on cytogenetic abnormalities of chromosome 7 in leiomyoma, together with those reported in the literature, are reviewed and discussed. A listing of the genes located at 7q22 is also presented.

The hepatocyte growth factor and its receptor

Hepatocyte growth factor/scatter factor (HGF/SF) is secreted by cells of mesodermal origin and shows powerful mitogenic, motogenic and morphogenic activities on epithelial and endothelial cells. It is a heparin-binding polypeptide with an alpha/beta heterodimeric structure, showing structural homologies with enzymes of the blood clotting cascade. HGF binds with high affinity to the receptor encoded by the MET protooncogene (p190MET). The MET receptor is a heterodimer of two disulfide-linked subunits (alpha and beta); the alpha subunit is extracellular, while the beta is transmembrane and endowed with tyrosine kinase activity. The HGF-triggered signalling is mediated by different cytoplasmic effectors, including phosphatidylinositol 3-kinase, phospholipase C-gamma, and Src-related tyrosine kinases. p190MET is expressed in several normal epithelial tissues (e.g., liver, gastrointestinal tract, kidney) and is often overexpressed in neoplastic cells. p190MET expression has been reported also in central nervous system microglia, a monocyte-derived cell population. We recently found that p190MET is expressed in selected peripheral blood cell populations, such as macrophages. The amount of both mRNA and protein is barely detectable, while it is dramatically increased upon activation. These findings suggest that HGF may play a role in hemopoietic cell signaling, during activation and differentiation of blood cell lineages.