RESUMO
Viral myocarditis has been found to be one of the leading causes of sudden death in young adults. However, no effective drugs have been developed to intervene the progression of myocarditis. Accordingly, the present study is carried out to explore the protective role played by melatonin in the setting of viral myocarditis with a focus on Mst1-Hippo pathway, mitochondrial dysfunction and ER stress. Cardiac function was determined via echocardiographic examination. Mitochondrial function and ER stress were detected via ELISA, western blots, and immunofluorescence. Our data demonstrated that virus injection induced cardiac dysfunction as evidenced by reduced contractile function in myocardium. Besides, LDH release assay and western blotting analysis demonstrated that cardiomyocyte death was activated by virus injection. Interestingly, melatonin treatment improved cardiac function and repressed virus-mediated cardiomyocyte apoptosis. At the molecular levels, mitochondrial dysfunction was induced by virus infection, as indicated by mitochondrial membrane potential reduction, mPTP opening rate elevation and caspase-9-related apoptosis activation. Besides, ER stress parameters were also elevated in virus-treated cardiomyocytes. Interestingly, melatonin treatment maintained mitochondrial dysfunction and repressed ER stress. To the end, we found that Mst1 was upregulated by virus infection; this effect was attenuated through supplementation with melatonin. However, Mst1 overexpression reduced the beneficial impact exerted by melatonin on cardiomyocyte viability, mitochondrial function and ER homeostasis. Our study illustrated that melatonin treatment attenuated viral myocarditis via sustaining cardiomyocyte viability, repressing mitochondrial dysfunction and inhibiting ER stress in a manner dependent on Mst1 inhibition.
Assuntos
Estresse do Retículo Endoplasmático/efeitos dos fármacos , Fator de Crescimento de Hepatócito/antagonistas & inibidores , Melatonina/farmacologia , Mitocôndrias/efeitos dos fármacos , Miocardite/prevenção & controle , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Animais , Sobrevivência Celular/efeitos dos fármacos , Fator de Crescimento de Hepatócito/metabolismo , Humanos , Mitocôndrias/patologia , Miócitos Cardíacos/efeitos dos fármacos , Substâncias Protetoras/farmacologia , Proteínas Proto-Oncogênicas/metabolismo , Vírus/patogenicidadeRESUMO
BACKGROUND: Sorafenib is the only approved first line systemic therapy for advanced hepatocellular carcinoma (HCC) in the last decade. Tumour resistance to sorafenib has been of major obstacles to improve HCC patient survival. METHODS: We polarised THP-1 cells to M1 and M2 macrophages, performed various in vitro assays and developed sorafenib-resistant xenograft models to investigate the role of tumour-associated macrophages (TAM)-secreted molecules in HCC resistance to the targeted therapy. RESULTS: We demonstrated M2, but not M1, macrophages not only promote proliferation, colony formation and migration of hepatoma cells but also significantly confer tumour resistance to sorafenib via sustaining tumour growth and metastasis by secreting hepatocyte growth factor (HGF). HGF activates HGF/c-Met, ERK1/2/MAPK and PI3K/AKT pathways in tumour cells. Tumour-associated M2 macrophages were accumulated in sorafenib-resistance tumours more than in sorafenib-sensitive tumours in vivo and produced abundant HGF. HGF chemoattracts more macrophages migrated from surrounding area, regulates the distribution of M2 macrophages and increases hepatoma resistance to sorafenib in a feed-forward manner. CONCLUSIONS: Our results provide new insights into the mechanisms of sorafenib resistance in HCC and rationale for developing new trials by combining sorafenib with a potent HGF inhibitor such as cabozantinib to improve the first line systemic therapeutic efficacy.
Assuntos
Antineoplásicos/uso terapêutico , Carcinoma Hepatocelular/tratamento farmacológico , Fator de Crescimento de Hepatócito/fisiologia , Neoplasias Hepáticas/tratamento farmacológico , Macrófagos/fisiologia , Sorafenibe/uso terapêutico , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos , MAP Quinases Reguladas por Sinal Extracelular/fisiologia , Fator de Crescimento de Hepatócito/antagonistas & inibidores , Humanos , Fosfatidilinositol 3-Quinases/fisiologia , Proteínas Proto-Oncogênicas c-akt/fisiologiaRESUMO
A lot of attention has been dedicated to investigate the role of the tyrosine kinase receptor MET in tumors. The acquired notion that cancer cells from different histological origin strictly rely on the engagement of this specific oncogene for their growth and survival has certainly justified the development and the use of MET-targeted therapies in the clinic. However, the function and involvement of this pathway in the stroma (that often constitutes >50% of the global cellularity of the tumor) may offer the opportunity to conceive new patient stratification criteria, rational drug design and guided trials of new combination treatments. In this review, we will summarize and discuss the role of MET in cancer cells but especially in different stromal compartments, in light of the results showed by past and recent preclinical and clinical trials with anti-MET drugs.
Assuntos
Neoplasias/genética , Neoplasias/metabolismo , Proteínas Proto-Oncogênicas c-met/genética , Proteínas Proto-Oncogênicas c-met/metabolismo , Células Estromais/metabolismo , Animais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Ensaios Clínicos como Assunto , Avaliação Pré-Clínica de Medicamentos , Regulação Neoplásica da Expressão Gênica , Fator de Crescimento de Hepatócito/antagonistas & inibidores , Fator de Crescimento de Hepatócito/metabolismo , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Proto-Oncogênicas c-met/antagonistas & inibidores , Transdução de Sinais , Células Estromais/patologia , Resultado do TratamentoRESUMO
BACKGROUND: Hepatocyte growth factor (HGF) is a cytokine that has a profound effect on cancer cells by stimulating migration and invasion and acting as an angiogenic factor. In lung cancer, the factor also plays a pivotal role and is linked to a poor outcome in patients. In particular, HGF is known to work in combination with EGF on lung cancer cells. In the present study, we investigated the effect of a traditional Chinese medicine reported in cancer therapies, namely YangZheng XiaoJi (YZXJ) on lung cancer and on HGF mediated migration and invasion of lung cancer cells. METHODS: Human lung cancer cells, SKMES1 and A549 were used in the study. An extract from the medicine was used. Cell migration was investigated using the EVOS and by ECIS. Cell-matrix adhesion and in vitro invasion were assessed. In vivo growth of lung cancer was tested using an in vivo xenograft tumour model and activation of the HGF receptor in lung tumours by an immunofluorescence method. RESULTS: Both lung cancer cells increased their migration in response to HGF and responded to YZXJ by reducing their speed of migration. YZXJ markedly reduced the migration and in vitro invasiveness induced by HGF. It worked synergistically with PHA665752 and SU11274, HGF receptor inhibitors on the lung cancer cells both on HGF receptor activation and on cell functions. A combination of HGF and EGF resulted in a greater increase in cell migration, which was similarly inhibited by YZXJ, and in combination with the HGF receptor and EGF receptor inhibitors. In vivo, YZXJ reduced the rate of tumour growth and potentiated the effects of PHA665752 on tumour growth. It was further revealed that YZXJ significantly reduced the degree of phosphorylation of the HGF receptor in lung tumours. CONCLUSION: YZXJ has a significant role in reducing the migration, invasion and in vivo tumour growth of lung cancer and acts to inhibit the migratory and invasive effects induced by HGF and indeed by HGF/EGF. This effect is likely attributed to the inhibition of the HGF receptor activation. These results indicate that YZXJ has a therapeutic role in lung cancer and that combined strategy with methods to block HGF and EGF should be considered.
Assuntos
Antineoplásicos/química , Medicamentos de Ervas Chinesas/química , Regulação Neoplásica da Expressão Gênica , Fator de Crescimento de Hepatócito/antagonistas & inibidores , Neoplasias Pulmonares/metabolismo , Proteínas Proto-Oncogênicas c-met/antagonistas & inibidores , Animais , Adesão Celular , Linhagem Celular Tumoral , Movimento Celular , Citocinas/metabolismo , Impedância Elétrica , Feminino , Fator de Crescimento de Hepatócito/metabolismo , Humanos , Concentração Inibidora 50 , Medicina Tradicional Chinesa , Camundongos , Camundongos Nus , Microscopia de Fluorescência , Neovascularização Fisiológica , Proteínas Proto-Oncogênicas c-met/metabolismo , Proteínas Recombinantes/metabolismo , Transdução de SinaisRESUMO
Metastasis is one of the major causes of cancer-related death. It is a complex biological process involving multiple genes, steps, and phases. It is also closely connected to many biological activities of cancer cells, such as growth, invasion, adhesion, hematogenous metastasis, and lymphatic metastasis. Fucoidan derived from Undaria pinnatifida sporophylls (Ups-fucoidan) is a sulfated polysaccharide with more biological activities than other fucoidans. However, there is no information on the effects of Ups-fucoidan on tumor invasion and metastasis. We used the mouse hepatocarcinoma Hca-F cell line, which has high invasive and lymphatic metastasis potential in vitro and in vivo, to examine the effect of Ups-fucoidan on cancer cell invasion and metastasis. Ups-fucoidan exerted a concentration- and time-dependent inhibitory effect on tumor metastasis in vivo and inhibited Hca-F cell growth, migration, invasion, and adhesion capabilities in vitro. Ups-fucoidan inhibited growth and metastasis by downregulating vascular endothelial growth factor (VEGF) C/VEGF receptor 3, hepatocyte growth factor/c-MET, cyclin D1, cyclin-dependent kinase 4, phosphorylated (p) phosphoinositide 3-kinase, p-Akt, p-extracellular signal regulated kinase (ERK) 1/2, and nuclear transcription factor-κB (NF-κB), and suppressed adhesion and invasion by downregulating L-Selectin, and upregulating protein levels of tissue inhibitor of metalloproteinases (TIMPs). The results suggest that Ups-fucoidan suppresses Hca-F cell growth, adhesion, invasion, and metastasis capabilities and that these functions are mediated through the mechanism involving inactivation of the NF-κB pathway mediated by PI3K/Akt and ERK signaling pathways.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Carcinoma Hepatocelular/tratamento farmacológico , Regulação Neoplásica da Expressão Gênica , Neoplasias Hepáticas Experimentais/tratamento farmacológico , Polissacarídeos/farmacologia , Undaria/química , Animais , Antineoplásicos Fitogênicos/isolamento & purificação , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patologia , Adesão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Ciclina D1/antagonistas & inibidores , Ciclina D1/genética , Ciclina D1/metabolismo , Quinase 4 Dependente de Ciclina/antagonistas & inibidores , Quinase 4 Dependente de Ciclina/genética , Quinase 4 Dependente de Ciclina/metabolismo , Relação Dose-Resposta a Droga , Fator de Crescimento de Hepatócito/antagonistas & inibidores , Fator de Crescimento de Hepatócito/genética , Fator de Crescimento de Hepatócito/metabolismo , Neoplasias Hepáticas Experimentais/genética , Neoplasias Hepáticas Experimentais/metabolismo , Neoplasias Hepáticas Experimentais/patologia , Metástase Linfática , Sistema de Sinalização das MAP Quinases , Masculino , Camundongos , NF-kappa B/antagonistas & inibidores , NF-kappa B/genética , NF-kappa B/metabolismo , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Inibidores de Fosfoinositídeo-3 Quinase , Extratos Vegetais/química , Polissacarídeos/isolamento & purificação , Proteínas Proto-Oncogênicas c-met/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-met/genética , Proteínas Proto-Oncogênicas c-met/metabolismo , Receptores de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores , Receptores de Fatores de Crescimento do Endotélio Vascular/genética , Receptores de Fatores de Crescimento do Endotélio Vascular/metabolismo , Fator A de Crescimento do Endotélio Vascular/antagonistas & inibidores , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Eucalyptin A (1), together with two known compounds 2 and 3 exhibiting potent inhibition on HGF/c-Met axis, was discovered from the fruits of Eucalyptus globulus. 1 possessed an unprecedented carbon framework of phloroglucinol-coupled sesquiterpenoid, and its structure was elucidated by spectroscopic method and ECD calculation. A brief structure-activity relationship discussion indicated that the coupling of a phloroglucinol and a sesquiterpenoid is essential for the activity.
Assuntos
Eucalyptus/química , Fator de Crescimento de Hepatócito/antagonistas & inibidores , Floroglucinol/química , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Proteínas Proto-Oncogênicas c-met/antagonistas & inibidores , Sesquiterpenos/química , Animais , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Cães , Fator de Crescimento de Hepatócito/farmacologia , Humanos , Células Madin Darby de Rim Canino , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Relação Estrutura-Atividade , Ativador de Plasminogênio Tipo Uroquinase/antagonistas & inibidoresRESUMO
Mutations/deletions of the tumor-suppressor phosphatase and tensin homolog PTEN result in PI3K/Akt pathway hyperactivation and potentially alter oncogenic responses to targeted receptor tyrosine kinase inhibitors. We previously showed that hepatocyte growth factor (HGF):c-Met pathway inhibition decreases tumor growth and oncogenic signaling responses in PTEN-null/Met+ gliomas. Here, we use two tet-on PTENwt-inducible glioma cell lines and xenograft models to examine the influence of PTEN on oncogenic signaling responses to HGF:c-Met pathway inhibitors. Reconstitution of PTEN inhibited Akt by more than 80% and inhibited cell growth by approximately 70-75% in both cell lines in vitro. C-Met inhibition alone inhibited in-vitro cell growth by approximately 80-85% and the magnitude of growth inhibition was not altered by combining PTEN reconstitution with c-Met inhibition. Combining PTEN reconstitution with Met inhibition arrested a higher percentage of cells in G(1)/G(0) phase of the cell cycle when compared with either PTEN reconstitution or c-Met inhibition alone. Both PTEN reconstitution alone and inhibiting autocrine HGF:c-Met signaling alone, using anti-HGF mAb, robustly inhibited the growth of subcutaneous and intracranial glioma xenografts. Combining anti-HGF therapy with PTEN reconstitution did not significantly alter the magnitude of xenograft growth inhibition. Semiquantitative immunohistopathological analyses revealed that the inhibition of glioma xenograft angiogenesis and cell proliferation by anti-HGF mAb was greatest in conjunction with PTEN reconstitution. In contrast, xenograft cell apoptosis was greatest in response to anti-HGF therapy alone and PTEN reconstitution abrogated the apoptotic response to anti-HGF therapy. These results provide new insights into how PTEN modulates glioma responses to the inhibition of HGF:c-Met signaling and possibly other receptor tyrosine kinase pathways.
Assuntos
Antineoplásicos/farmacologia , Glioma/tratamento farmacológico , Indóis/farmacologia , PTEN Fosfo-Hidrolase/metabolismo , Piperazinas/farmacologia , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-met/antagonistas & inibidores , Sulfonamidas/farmacologia , Sulfonas/farmacologia , Animais , Anticorpos Monoclonais/farmacologia , Apoptose/efeitos dos fármacos , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Avaliação Pré-Clínica de Medicamentos , Feminino , Glioma/metabolismo , Glioma/patologia , Fator de Crescimento de Hepatócito/antagonistas & inibidores , Fator de Crescimento de Hepatócito/metabolismo , Humanos , Camundongos , Camundongos Nus , Camundongos SCID , Terapia de Alvo Molecular , Fosfatidilinositol 3-Quinases , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Proto-Oncogênicas c-met/metabolismo , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de Sinais , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Hepatocyte growth factor (HGF) and c-Met have recently attracted a great deal of attention as prognostic indicators of patient outcome, and they are important in the control of tumor growth and invasion. Epigallocatechin-3-gallate (EGCG) has been shown to modulate multiple signal pathways in a manner that controls the unwanted proliferation and invasion of cells, thereby imparting cancer chemopreventive and therapeutic effects. In this study, we investigated the effects of EGCG in inhibiting HGF-induced tumor growth and invasion of oral cancer in vitro and in vivo. We examined the effects of EGCG on HGF-induced cell proliferation, migration, invasion, induction of apoptosis and modulation of HGF/c-Met signaling pathway in the KB oral cancer cell line. We investigated the antitumor effect and inhibition of c-Met expression by EGCG in a syngeneic mouse model (C3H/HeJ mice, SCC VII/SF cell line). HGF promoted cell proliferation, migration, invasion and induction of MMP (matrix metalloproteinase)-2 and MMP-9 in KB cells. EGCG significantly inhibited HGF-induced phosphorylation of Met and cell growth, invasion and expression of MMP-2 and MMP-9. EGCG blocked HGF-induced phosphorylation of c-Met and that of the downstream kinases AKT and ERK, and inhibition of p-AKT and p-ERK by EGCG was associated with marked increases in the phosphorylation of p38, JNK, cleaved caspase-3 and poly-ADP-ribose polymerase. In C3H/HeJ syngeneic mice, as an in vivo model, tumor growth was suppressed and apoptosis was increased by EGCG. Our results suggest that EGCG may be a potential therapeutic agent to inhibit HGF-induced tumor growth and invasion in oral cancer.
Assuntos
Catequina/análogos & derivados , Fator de Crescimento de Hepatócito/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-met/antagonistas & inibidores , Animais , Catequina/farmacologia , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Quimioprevenção , Progressão da Doença , Feminino , Humanos , Células KB , Metaloproteinase 2 da Matriz/biossíntese , Metaloproteinase 9 da Matriz/biossíntese , Camundongos , Neoplasias Bucais/patologia , Invasividade Neoplásica , Proteínas Proto-Oncogênicas c-met/biossíntese , Transdução de Sinais/efeitos dos fármacos , CháRESUMO
The aim of this study was to evaluate the effect and elucidate the potential mechanism of the extract of rhizomes from Dioscorea alata L. cv. Phyto, Dispo85E, on accelerating the elimination of advanced glycation end products (AGEs) in vitro and in vivo. Primary mouse nonparenchymal cells (NPCs) were used to evaluate the drug effect on AGEs clearance and autophagic-lysosomal activity. In an animal study, we used AGEs-induced diabetic mice to evaluate the drug effect on AGEs-induced vascular complications. Our results indicated that Dispo85E enhanced the endocytosis and degradation activity of AGEs in hepatic NPCs. Furthermore, the hepatocyte growth factor (HGF) expression level was positively correlated with the clearance capacity of the AGEs in NPCs after Dispo85E treatment. In addition, the effects of Dispo85E on the degradation and uptake capability of (14)C-AGEs were abolished in the presence of an anti-HGF neutralizing antibody. We further demonstrated that recombinant mouse HGF could enhance the endocytosis and autophagic clearance of AGEs in NPCs. The in vivo data indicated that Dispo85E increased hepatic HGF messenger RNA expression levels and decreased serum AGEs level in diabetic mice. Moreover, the function of retina and kidneys was improved by Dispo85E treatment in AGEs-induced diabetic mice. These results suggest that HGF may have an important role in the elimination of AGEs. This study suggests that Dispo85E is a botanical drug with a novel mechanism that enhances the clearance of AGEs through HGF-induced autophagic-lysosomal pathway and is a candidate drug for the treatment of diabetic vascular complications.
Assuntos
Autofagia/efeitos dos fármacos , Angiopatias Diabéticas/tratamento farmacológico , Angiopatias Diabéticas/metabolismo , Dioscorea/química , Produtos Finais de Glicação Avançada/metabolismo , Fator de Crescimento de Hepatócito/fisiologia , Hipoglicemiantes/uso terapêutico , Extratos Vegetais/uso terapêutico , Animais , Anticorpos Bloqueadores/farmacologia , Nefropatias Diabéticas/tratamento farmacológico , Nefropatias Diabéticas/patologia , Retinopatia Diabética/tratamento farmacológico , Retinopatia Diabética/patologia , Fator de Crescimento de Hepatócito/antagonistas & inibidores , Fator de Crescimento de Hepatócito/biossíntese , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Lisossomos/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fitoterapia , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Rizoma/químicaRESUMO
Malaria is the number one disease in the world responsible for 1-3 million deaths each year. The world wide number of malaria patients is estimated at 400 to 900 million. Approximately one third of the world's population lives in malaria-endemic areas, including Central and South America, Asia, and Africa. Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale and Plasmodium malariae are malaria parasites responsible for infecting humans. Mosquitoes that carry malaria parasites have become resistant to insecticides, and the deadliest parasites have become resistant to previously effective antimalarial drugs such as chloroquine, quinine and other clinically used agents. Because of the widespread incidence of malaria in certain parts of the world and because of the increasing parasite resistance to standard anti-malarial agents, there is an urgent need for introducing new effective drugs. This review presents the recent patents that reveal development of novel antimalarial drugs.
Assuntos
Antimaláricos/farmacologia , Malária/tratamento farmacológico , Aminoquinolinas/síntese química , Aminoquinolinas/farmacologia , Aminoquinolinas/uso terapêutico , Animais , Antígenos de Protozoários/imunologia , Antígenos de Protozoários/uso terapêutico , Antimaláricos/síntese química , Antimaláricos/uso terapêutico , Artemisininas/farmacologia , Artemisininas/uso terapêutico , Bioensaio , Flavonoides/farmacologia , Flavonoides/uso terapêutico , Fator de Crescimento de Hepatócito/antagonistas & inibidores , Humanos , Vacinas Antimaláricas/uso terapêutico , Patentes como Assunto , Extratos Vegetais/farmacologia , Primaquina/análogos & derivados , Primaquina/farmacologia , Inibidores de Proteases/farmacologia , Inibidores de Proteases/uso terapêutico , Quinazolinas/síntese química , Quinazolinas/farmacologia , Quinazolinas/uso terapêutico , Triazinas/farmacologia , Triazinas/uso terapêuticoRESUMO
In addition to regulation of normal cell functions, hepatocyte growth factor (HGF) has also been shown to be involved in malignant cell transformation and in growth, invasion and metastasis in cancer cells. Inhibitors of HGF production have a potential for interfering with malignant cell transformation and progression of tumors. We found that tryptanthrin, one of the major compounds extracted from the medicinal plant Polygonum tinctorium, which is known for its antitumor activity, strongly inhibited HGF production stimulated by various HGF inducers in human dermal fibroblasts. HGF production induced by phorbol 12-myristate 13-acetate (PMA) was potently inhibited by tryptanthrin without any appreciable cytotoxic effect. Tryptanthrin also inhibited HGF production induced by epidermal growth factor (EGF) and platelet-derived growth factor. Moreover, proliferation of the fibroblasts induced by the two growth factors was potently suppressed by tryptanthrin to the level of proliferation of unstimulated fibroblasts. However, tryptanthrin did not inhibit HGF production induced by the protein kinase A-activating agents cholera toxin and 8-bromo-cAMP. These effects of tryptanthrin were different from the effects of transforming growth factor beta1 and dexamethasone, both of which inhibit HGF production induced by all the above inducers. Upregulations of HGF gene expression by PMA and EGF were also inhibited by tryptanthrin. Activation of the mitogen-activated protein kinase (MAPK) signaling pathway is crucial for PMA-induced HGF production, but tryptanthrin did not attenuate phosphorylation of MAPK induced by PMA. These results indicate that tryptanthrin potently inhibited induction of HGF production probably through events downstream of MAPK activation.
Assuntos
Fibroblastos/efeitos dos fármacos , Fator de Crescimento de Hepatócito/antagonistas & inibidores , Fator de Crescimento de Hepatócito/biossíntese , Quinazolinas/farmacologia , Pele/efeitos dos fármacos , Células Cultivadas , Relação Dose-Resposta a Droga , Fibroblastos/metabolismo , Fator de Crescimento de Hepatócito/metabolismo , Humanos , Recém-Nascido , Pele/metabolismoRESUMO
Hepatocyte growth factor/scatter factor (HGF/SF) stimulates cell proliferation, motility, and morphogenesis by activation of its receptor, the c-Met tyrosine kinase. HGF/SF is structurally related to plasminogen, including an amino-terminal hairpin loop, four kringle domains, and a serine protease-like region. A truncated HGF/SF isoform, designated HGF/NK2, which extends through the second kringle domain and behaves as a competitive HGF/SF antagonist, was previously shown to be encoded by an alternative HGF/SF transcript. In this study, we describe a second naturally occurring HGF/SF variant, HGF/NK1, consisting of the HGF/SF amino-terminal sequence and first kringle domain. This product is encoded by a 2-kilobase alternative transcript containing intronic sequence that was contiguous with exon K1b. Analysis of baculovirus-expressed HGF/NK1 revealed that this isoform possesses the heparin binding properties of HGF/SF and modest mitogenic and scattering activity relative to HGF/SF. However, at a 40-fold molar excess, HGF/NK1 inhibited HGF/SF-dependent DNA synthesis. HGF/NK1 stimulated tyrosine phosphorylation of Met, and covalent affinity cross-linking demonstrated a direct HGF/NK1-receptor interaction. These findings establish that the HGF/SF gene encodes multiple alternative products, which include not only a mitogenic agonist (HGF/SF) and a pure antagonist (HGF/NK2) but also a molecule with partial agonist/antagonist properties.