Expression Of Hepatocyte Growth Factor Receptor Research Articles

Combined Expression of HGFR with Her2/neu, EGFR, IGF1R, Mucin-1 and Integrin α2β1 Is Associated with Aggressive Epithelial Ovarian Cancer

Hepatocyte growth factor receptor (HGFR), also known as c-mesenchymal-epithelial transition factor (c-MET), plays a crucial role in the carcinogenesis of epithelial ovarian cancer (EOC). In contrast, the mechanisms contributing to aberrant expression of HGFR in EOC are not fully understood. In the present study, the expression of HGFR with its prognostic and predictive role was evaluated immunohistochemically in a cohort of 42 primary ovarian cancer patients. Furthermore, we analyzed the dual expression of HGFR and other druggable biomarkers. In the multivariate Cox regression analysis, high HGFR expression was identified as an independent prognostic factor for a shorter progression-free survival (PFS) (hazard ratio (HR) 2.99, 95% confidence interval (CI95%) 1.01-8.91, p = 0.049) and overall survival (OS) (HR 5.77, CI95% 1.56-21.34, p = 0.009). In addition, the combined expression of HGFR, human epidermal growth factor receptor 2 (Her2/neu), epithelial growth factor receptor (EGFR), insulin-like growth factor 1 (IGF1R), Mucin-1 and Integrin α2β1 further significantly impaired PFS, platinum-free interval (PFI) and OS. Protein co-expression analyses were confirmed by transcriptomic data in a large, independent cohort of patients. In conclusion, new biomarker-directed treatment targets were identified to fight poor prognosis of primary EOC.

Mammary Tumor Cells with High Metastatic Potential Are Hypersensitive to Macrophage-Derived HGF.

Metastasis-associated macrophages (MAM) promote persistent growth of breast cancer cells at the metastatic site and are, thus, an attractive therapeutic target to treat breast cancer metastasis, a leading cause of cancer-related death in women. However, the precise mechanisms behind MAM-mediated metastatic tumor outgrowth have not been fully elucidated. Using mouse models of metastatic breast cancer, we showed that MAMs uniquely expressed hepatocyte growth factor (HGF) in metastatic tumors. We also demonstrated that a selected population of cancer cells with high metastatic potential (cancer cells that can establish metastatic tumors in mice with higher number and incidence than parental cells) had higher expression of HGF receptor, MNNG HOS transforming gene (MET), and were more responsive to HGF released from macrophages compared with the parental cells. Blockade of MET signaling in cancer cells suppressed metastatic tumor expansion, in part, through activation of natural killer cells. Results from this study suggest an approach to prevent life-threatening metastatic tumor formation using blockade of MAM-induced MET signal activation in metastatic cancer cells.

Effect of brefelamide on HGF-induced survival of 1321N1 human astrocytoma cells.

Malignant gliomas are characterized by their high level of resistance to chemo- and radiotherapy and new treatment options are urgently required. We previously demonstrated that brefelamide, an aromatic amide isolated from methanol extracts of cellular slime molds Dictyostelium brefeldianum and D. giganteum, had antiproliferative effects on 1321N1 human astrocytoma cells, a model of glioma. In this study, we investigated the mechanisms by which brefelamide inhibited 1321N1 and PC12 rat pheochromocytoma cell proliferation. When cells were cultured in serum-free medium, hepatocyte growth factor (HGF) increased survival of 1321N1 cells but not PC12 cells. HGF receptor, c-MET, was strongly expressed in 1321N1 cells, but not in PC12 cells. Pretreatment of 1321N1 cells with brefelamide inhibited both HGF-induced cell survival and expression of c-MET. Phosphorylation of extracellular signal-regulated kinase (ERK) and AKT was increased by HGF, but these changes were inhibited by brefelamide pretreatment. Moreover, HGF mRNA levels and secretion were reduced by brefelamide. These results suggest that brefelamide reduces survival of 1321N1 cells via multiple effects including suppression of HGF receptor expression and HGF secretion and inhibition of ERK and AKT phosphorylation.

Prognostic Value of Hepatocyte Growth Factor Receptor Expression in Patients with Perihilar Cholangiocarcinoma

Although an aggressive surgical approach to perihilar cholangiocarcinoma (PHC) has improved survival, a prognosis of advanced PHC remains unsatisfactory. The overexpression of mesenchymal-epithelial transition factor (MET) and recepteur d'origine nantais (RON) has been shown to be associated with poor prognosis in some types of cancer. One hundred sixty-nine patients who underwent histologically curative resection for PHC were subjected to immunohistochemical analysis for MET and RON. The association between a positive expression of MET or RON and clinicopathologic features as well as the patients' prognosis were analyzed. There were 27 patients (16 %) who had a positive expression for both MET and RON. Although clinicopathologic features in the either MET- or RON-negative group were not significantly different compared to the both MET- and RON-positive group, the prognosis tended to be worse in the patients with both MET and RON positivity. When the analysis was limited to patients with advanced-stage disease (stage III and IVa), a multivariate analysis revealed that both MET and RON positivity and lymph node metastasis were identified as independent poor prognostic factors. The overall survival rate for patients with both MET and RON positivity was worse than that with either MET or RON negativity in patients with advanced PHC. The poor prognosis in these patients was not associated with unfavorable clinicopathologic features. The examination of MET and RON expression in PHC may enable a tailored method for patient classification that could not otherwise be achieved using the conventional pathologic classification system.

Hepatocyte growth factor profile with breast cancer

The multifunctional hepatocyte growth factor (HGF) is the ligand of c-Met receptor; it plays important role in mammary differentiation. HGF-Met signaling is a critical downstream function of c-Src-Stat3 pathway in mammalian tumorigenesis. Evaluation of tissue c-Met receptor hepatocyte growth factor receptor (HGFR) and serum level of HGF in female breast ductal carcinoma. Sixty-eight premenopausal females were divided as 30 control females subdivided into: [Group 1] 15 healthy volunteer females and [Group 2] five with fibrocystic disease and 10 having fibroadenoma of the breast and patients group [Group 3] consisted of 38 female patients with breast ductal carcinoma. Thorough clinical examination, preoperative fine needle aspiration cytology, estimation of fasting serum glucose, urea, creatinine, and uric acid levels, alanine aminotransferase activities, C-reactive protein, HGF level, before surgery and histopathological examination of the breast masses, and immunohistochemical detection of HGFR were done. Significant increase in serum HGF levels were found in patients with breast cancer as compared with controls. Significant increase was also seen in patients with breast cancer with and without lymph node metastasis when each subgroup was compared with controls. Serum level of HGF is an independent prognostic indicator of breast cancer. Fibrocystic disease of the breast showed weak HGFR expression, while in normal tissue, HGFR was scanty; meanwhile, breast invasive ductal carcinoma showed homogenous strong reaction to HGFR. HGF is only one of a number of key factors involved in breast cancer and preoperative high serum HGF levels and malignancy occur usually together.

Regulation of epithelial cell growth factor receptor protein and gene expression using a rat periodontitis model

Regulation of epithelial cell behavior associated with periodontitis is not well elucidated but many responses will ultimately be regulated by growth factor receptors. Using a rat experimental periodontitis model, protein and gene expression of select growth factor receptors in junctional and pocket epithelium were examined. Periodontal disease was induced by daily topical application of lipopolysaccharide using an established protocol. Animals were killed at time 0 (control), and at 2 and 8 wk. Frozen tissue samples were collected from the right palatal gingival soft tissue, and the left periodontal tissues were decalcified and embedded in paraffin. Laser microdissection and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to quantify keratinocyte growth factor receptor (KGFR), hepatocyte growth factor receptor (HGFR), epidermal growth factor receptor (EGFR) and fibroblast growth factor receptor 1 (FGFR1) gene expression, and in situ RT-PCR localized these increases to specific epithelial cells. Receptor protein expression was examined immunohistochemically. In cell culture, induction of HGFR and KGFR protein expression by serum, lipopolysaccharide and pro-inflammatory cytokines were examined using flow cytometry. Eight-week tissue samples exhibited histological changes consistent with periodontitis. KGFR and HGFR gene and protein expression were significantly induced at the 8 wk time point. KGFR expression was significantly up-regulated in basal and parabasal pocket epithelial cells, but HGFR was up-regulated throughout the pocket epithelium. In cell culture serum, lipopolysaccharide and pro-inflammatory cytokines, interleukin-1beta and tumour necrosis factor-alpha significantly induced KGFR protein receptor expression, but HGFR expression was only induced by serum. KGFR and HGFR are highly up-regulated in this model of periodontal disease and may play a significant role in regulating the proliferation and migration of pocket epithelium.

Extent of over-expression of hepatocyte growth factor receptor in colorectal tumours is dependent on the choice of normaliser

For reliable results from quantitative RT-PCR, the starting quantity of total RNA and other parameters need to be controlled. Most studies do this by normalising their results to a single reference gene. This study quantified the mRNA expression of three putative reference genes (ubiquitin C, cyclophilin E, and porphobilinogen deaminase) and the target gene hepatocyte growth factor receptor (HGFR) in matched colorectal tumour and normal mucosa samples. Each of the putative reference genes was found to be significantly over-expressed in the tumour samples compared to the normal samples. When HGFR expression was normalised to each of these reference genes using the 2 - Δ Δ C T method of relative quantification, the number of tumour samples in which HGFR was found to be over-expressed varied from 30% to 63% depending on the reference gene chosen for normalisation. This shows that normalising to a single reference gene without prior validation is inappropriate.

Hepatocyte growth factor promotes lymphatic vessel formation and function

The lymphatic vascular system plays a pivotal role in mediating tissue fluid homeostasis and cancer metastasis, but the molecular mechanisms that regulate its formation and function remain poorly characterized. A comparative analysis of the gene expression of purified lymphatic endothelial cells (LEC) versus blood vascular endothelial cells (BVEC) revealed that LEC express significantly higher levels of hepatocyte growth factor receptor (HGF-R). Whereas little or no HGF-R expression was detected by lymphatic vessels of normal tissues, HGF-R was strongly expressed by regenerating lymphatic endothelium during tissue repair and by activated lymphatic vessels in inflamed skin. Treatment of cultured LEC with HGF promoted LEC proliferation, migration and tube formation. HGF-induced proliferation of LEC did not require vascular endothelial growth factor receptor-3 activation, and HGF-induced cell migration was partially mediated via integrin alpha-9. Transgenic or subcutaneous delivery of HGF promoted lymphatic vessel formation in mice, whereas systemic blockade of HGF-R inhibited lymphatic function. These results identify HGF as a novel, potent lymphangiogenesis factor, and also indicate that HGF-R might serve as a new target for inhibiting pathological lymphangiogenesis.

Both Sp1 and Smad participate in mediating TGF-beta1-induced HGF receptor expression in renal epithelial cells.

Hepatocyte growth factor (HGF) receptor is a transmembrane receptor tyrosine kinase encoded by the c-met protooncogene. In this study, we demonstrated that c-met expression was upregulated in the kidney after obstructive injury in mice. Because the pattern of c-met induction was closely correlated with transforming growth factor-beta1 (TGF-beta1) expression in vivo, we further investigated the regulation of c-met expression in renal tubular epithelial (HKC) cells by TGF-beta1 in vitro. Real-time RT-PCR and Northern and Western blot analyses revealed that TGF-beta1 significantly induced c-met expression in HKC cells, which primarily took place at the gene transcriptional level. Overexpression of inhibitory Smad7 completely abolished c-met induction, indicating its dependence on Smad signaling. Interestingly, TGF-beta1-induced c-met expression was also contingent on a functional Sp1, as ablation of Sp1 binding with mithramycin A abrogated c-met induction in HKC cells. Transfection and sequence analysis identified a cis-acting TGF-beta1-responsive region in the c-met promoter, in which resided a putative Smad-binding element (SBE) and an adjacent Sp1 site. TGF-beta1 not only induced Smad binding to the SBE/Sp1 sites in the c-met promoter, but also enhanced the binding of Sp proteins. Furthermore, Sp1 could form a complex with Smads in a TGF-beta1-dependent fashion. These results suggest a novel regulatory mechanism controlling c-met expression by TGF-beta1 in renal epithelial cells, in which both Smad and Sp proteins participate and cooperate in activating c-met gene transcription.

Autocrine Activation of the Hepatocyte Growth Factor Receptor/Met Tyrosine Kinase Induces Tumor Cell Motility by Regulating Pseudopodial Protrusion

The multiple beta-actin rich pseudopodial protrusions of the invasive variant of Moloney sarcoma virus (MSV)-transformed epithelial MDCK cells (MSV-MDCK-INV) are strongly labeled for phosphotyrosine. Increased tyrosine phosphorylation among a number of proteins was detected in MSV-MDCK-INV cells relative to untransformed and MSV-transformed MDCK cells, especially for the hepatocyte growth factor receptor (HGF-R), otherwise known as c-met proto-oncogene. Cell surface expression of HGF-R was similar in the three cell lines, indicating that HGF-R is constitutively phosphorylated in MSV-MDCK-INV cells. Both the tyrosine kinase inhibitor herbimycin A and the HGFalpha antibody abolished HGF-R phosphorylation, induced retraction of pseudopodial protrusions, and promoted the establishment of cell-cell contacts as well as the apparition of numerous stabilizing stress fibers in MSV-MDCK-INV cells. Furthermore, anti-HGFalpha antibody abolished cell motility among MSV-MDCK-INV cells. Conditioned medium from MSV-MDCK-INV cells induced MDCK cell scattering, indicating that HGF is secreted by MSV-MDCK-INV cells. HGF titration followed by a subsequent washout of the antibodies led to renewed pseudopodial protrusion and cellular movement. We therefore show that activation of the tyrosine kinase activity of HGF-R/Met via an autocrine HGF loop is directly responsible for pseudopodial protrusion, thereby explaining the motile and invasive potential of this model epithelium-derived tumor cell line.

Cell turnover in normal and abnormal kidney development.

As metanephric mesenchyme converts into nephrons, the first step is aggregation into a 'condensate'. Precursors inside this structure are proliferative and have a low rate of apoptosis, accompanied by expression of PAX-2 and BCL-2 survival molecules; conversely, cells at the borders of the structure have a high rate of apoptosis, probably a normal mechanism to regulate the number of cells in each nephron. Ureteric bud/collecting duct survival and mitosis may be determined partly by renal mesenchymal secreted molecules such as hepatocyte growth factor (HGF) and glial cell line-derived neurotrophic factor. Human kidney malformations often occur with lower urinary tract obstruction, e.g. cystic dysplastic kidneys caused by urethral valves. Deregulation of cell turnover occurs in these organs, with enhanced proliferation in cystic epithelium, accompanied by PAX-2, BCL-2 and HGF receptor expression, and apoptosis in surrounding mesenchyme, which transdifferentiates under the influence of transforming growth factor-beta1 into smooth muscle instead of forming nephrons. Similar abnormalities of cell turnover and gene expression can be generated by experimental fetal urinary flow impairment. Finally, renal mesenchymal apoptosis, associated with renal hypoplasia, can be induced experimentally by maternal low protein diet.

Overexpression of the Hepatocyte Growth Factor (HGF) Receptor (Met) and Presence of a Truncated and Activated Intracellular HGF Receptor Fragment in Locally Aggressive/Malignant Human Musculoskeletal Tumors

Enhanced hepatocyte growth factor (HGF) receptor (Met) signaling has been suggested to play an important role in the development and progression of various epithelial and nonepithelial tumors. N-terminally truncated forms of the HGF receptor have been shown to be constitutively activated and tumorigenic in animal experiments. In the present study, 102 benign and malignant human musculoskeletal tumors were examined for expression of the HGF receptor by Western blotting and/or immunohistochemistry. A clear predominance of HGF receptor expression was seen in malignant as compared to benign tumors (Western blotting, P < 0.001; immunohistochemistry, P < 0.02). For the first time we show HGF receptor expression in the following four tumor types: dermatofibrosarcoma protuberans, clear cell sarcoma of tendons, malignant primitive neuroectodermal tumor, and benign fibrous histiocytoma. In three cases of sarcoma with high HGF receptor expression by Western blotting, we found indications of a short 85-kd N-terminally truncated HGF receptor that was tyrosine phosphorylated and located in the cytoplasm. Although fragments of this length were seen in 18 of 65 tumors, most were not tyrosine-phosphorylated. Northern blotting revealed only the 7.5-kb full-length HGF receptor transcript, suggesting that the 85-kd fragment is generated by an alternative initiation of translation or by proteolytic cleavage. Southern blotting detected no amplification of the Hgfr/Met gene in the 35 tumors examined, in contrast to our recent report of Hgfr/Met gene amplification in 7, 12-dimethylbenz(a)anthracene (DMBA)-induced rat sarcomas. The present data suggest that the locally aggressive and malignant properties of human mesenchymal tumors maybe related, in part, to high levels of full-length HGF receptors, and in some cases to the occurrence of N-terminally truncated HGF receptors, activated independently of HGF.

Gene expression of hepatocyte growth factor and its receptor in HCC and nontumorous liver tissues.

AIM:To study the changes of gene expression of hepatocyte growth factor (HGF) and hepatocyte growth factor receptor (HGFr) in hepatocellular carcinoma (HCC) tissue and nontumorous liver tissue and the relationship between these changes and the biological behavior of the tumor.METHODS:Gene expression of HGF and HGFr in 26 cases of HCC tissue and their adjacent nontumorous liver tissues was determined with digoxigenin labeled DNA probes.RESULTS:Positive expression of HGF in HCC tissue was similar to that in the adjacent nontumorous liver tissue, but positive rate of HGF expression was lower than HGFr gene expression. However, HGFr expression was higher in the metastatic cases than in those without metastasis. It was found that HGFr was overexpressed in HCC tissue as well as in the adjacent nontumorous liver tissue.CONCLUSION:There seems to be a close relationship between overexpression of HGFr gene and tumor metastasis, and the HGF and HGFr system plays an important role in regulating tumor growth and metastasis.

C-met expression in pancreatic cancer and effects of hepatocyte growth factor on pancreatic cancer cell growth.

Hepatocyte growth factor (HGF) is a widely expressed growth factor secreted by cells of mesenchymal origin, which has been shown to be involved in growth processes of multiple cell types. The HGF receptor, the product of the c-met protooncogene, is expressed mainly by epithelial cells. Increased expression of the HGF receptor has been observed in various tumors. To investigate the expression of the HGF receptor in the pancreas, we analyzed rat and human normal tissue and pancreatic carcinoma by Western blot analysis. We observed weak expression of c-met reactivity in normal pancreas but markedly enhanced expression in both rat and human pancreatic cancer. To test the possibility that HGF could act as a growth factor on pancreatic carcinoma, the effects of HGF on DNA synthesis in a rat and two human pancreatic carcinoma cell lines were analyzed. HGF induced dose-dependent [3H]thymidine incorporation, reaching 320, 210, and 180% above unstimulated controls in AR4-2J, PancTu-1, and 818/4 cells, respectively. The activation of signal transduction pathways by HGF was further analyzed in AR4-2J cells. After stimulation, a rapid and intense increase in receptor tyrosine phosphorylation was detected. Furthermore, HGF induced a time- and dose-dependent induction of c-fos expression. The addition of tyrphostin, a specific tyrosine kinase inhibitor, prevented c-fos induction and inhibited HGF-induced [3H]thymidine incorporation. In summary, our results demonstrate strongly increased HGF receptor expression in pancreatic carcinoma and support the assumption that HGF could act as a growth promoting factor on this cancer via stimulation of tyrosine kinases.

In vivo and in vitro evidence for increased expression of HGF receptor in kidney of diabetic rat.

Renal hypertrophy develops early in the course of diabetes and has been linked to progressive renal disease. Although the mechanism of renal hypertrophy is unknown, evidence suggests that local alterations in the production of one or more growth factors and/or their receptors are crucial to this process. In this study, we demonstrate that the c-met protooncogene product, a tyrosine kinase receptor for hepatocyte growth factor (HGF), is increased in the kidney of the diabetic rat. Northern blot analysis showed that renal expression of the c-met gene was substantially increased in rats made diabetic by administration of streptozotocin. Immunohistochemical studies revealed that the protein for c-met was concordantly elevated in cortical and medullar tubular epithelium following the onset of diabetes. Moreover, in vitro studies demonstrated that short-term exposure to high glucose concentration markedly stimulated c-met expression in cultured proximal tubular (opossum kidney) and inner medulla collecting duct cells (mIMCD-3). The results of enhanced renal expression of c-met together with elevated HGF indicate that the HGF/c-met system is markedly activated in the diabetic rat. These findings suggest that the HGF/c-met system may play a role in the diabetic renal hypertrophy.

Hepatocyte growth factor (HGF) receptor expression is inducible and is part of the delayed-early response to HGF.

The c-MET proto-oncogene encodes the tyrosine kinase receptor for hepatocyte growth factor (HGF), also known as scatter factor, a potent mitogen and motogen for epithelial cells. The level of the HGF receptor expressed by epithelial cells varies in different growth conditions, being lower in growth arrested confluent monolayers and higher in growing sparse cells. The amount of HGF receptor mRNA increases from 3- to 5-fold after stimulation of confluent monolayers by serum and up to 10-fold after stimulation of protein kinase C by 12-O-tetradecanoylphorbol-13-acetate (TPA). An increased level of the receptor mRNA was also observed after cell stimulation with nanomolar concentration of HGF itself. The effect was transient, dose, and time-dependent. Transcription of a reporter gene under control of the cloned 297 base pair c-MET promoter was also stimulated by serum, TPA, or HGF. The accumulation of specific mRNA is followed by appearance of the HGF receptor precursor protein, which is further processed to the receptor mature form. After HGF stimulation, HGF receptor expression follows c-FOS and c-JUN induction with a peak approximately 4 h. Pretreatment with the protein synthesis inhibitor puromycin strongly reduced the response to HGF, while cycloheximide alone increased the level of the receptor mRNA. These data show that c-MET behaves as a delayed early-response gene and suggest that the HGF response is autoamplified by inducing the specific receptor.

Cell density-dependent regulation of hepatocyte growth factor receptor on adult rat hepatocytes in primary culture.

The proliferative potential of hepatocytes in the normal intact liver is highly suppressed, but they proliferate actively after liver injury. In this study, adult rat hepatocytes in primary culture were used to study mechanisms controlling hepatocyte growth in liver regeneration. DNA synthesis in hepatocytes cultured at a low cell density was highly stimulated in response to hepatocyte growth factor (HGF), but this stimulatory effect was not so obvious in hepatocytes cultured at a high cell density. In close parallel to the potency of DNA synthesis, the amounts of 125I-HGF specifically bound to hepatocytes cultured at a low cell density were much greater than in high cell density culture. Scatchard plots revealed that change in the specific binding of 125I-HGF was due to change in the number of high-affinity HGF receptors, but without change in the Kd values. Affinity cross-linking of the HGF receptor with 125I-HGF confirmed the higher expression of HGF receptor on hepatocytes cultured at a lower cell density. Since there was no significant change in the expression of c-met mRNA in hepatocytes cultured at different cell densities, the number of cell surface HGF receptors is probably regulated by post-transcriptional mechanisms. We also found that the rates of HGF-induced down-regulation and recovery of HGF receptors on hepatocytes cultured at a low cell density were much faster than in cases of a high cell density.(ABSTRACT TRUNCATED AT 250 WORDS)