HGF/c-MET通路在癌症中的研究进展

近年来,HGF/c-MET信号通路正成为学术界研究的热点,HGF/c-MET通路在肿瘤的发生发展中扮演着非常重要的角色,并参与肿瘤的侵袭和转移。该通路的标志特征是HGF与其配体c-MET蛋白的结合引起一系列信号传导的酶促反应[1],并由c-MET下游停泊蛋白-生长因子受体结合蛋白2(GRB2)及接头蛋白1(GAB1)[2]的激活和该信号通路与其他信号通路间的交联而起作用[1,3]。     

Wnt/β-catenin信号通路在胰腺癌中的研究进展

靶向治疗在肿瘤治疗中具有广阔应用前景.以信号通路为靶点的研究显得尤为重要,成为了靶向治疗的基石.研究证实Wnt/β -catenin信号通路在胰腺癌的发生、发展中起着重要作用.抑制该信号通路能起到抗肿瘤作用,有可能成为候选的靶向治疗靶点,值得进一步研究.本文就Wnt/β -catenin信号通路在胰腺癌中的作用作一综述.     

NDRG2调控HGF/c-MET通路抑制结肠癌细胞的增殖

目的:探讨抑癌基因NDRG2通过调节HGF/c-MET信号通路,抑制结肠癌HT29细胞增殖的机制。方法:建立NDRG2过表达细胞株HT29-NDRG2及对照组HT29-Cherry,并于第1、2、3、4、5天以MTT法检测细胞增殖;以不同浓度的HGF（0ng/ml、1ng/ml、2ng/ml、4ng/ml、8ng/ml、10ng/ml）刺激HT29亲本细胞,并于第1、2、3天以MTT法检测HT29细胞的增殖;采用qPCR法检测NDRG2过表达细胞株HT29-NDRG2与对照组HT29-Cherry两组细胞中HGF的表达水平;Western blot检测HT29-Cherry和HT29-NDRG2两组细胞以及添加HGF（10ng/ml）刺激HT29亲本细胞后各组细胞中HGF/c-MET通路中关键分子的表达。结果:过表达NDRG2以及HGF刺激均可以显著抑制HT29细胞的增殖能力;NDRG2的高表达可以上调HGF的转录水平;HGF可以刺激c-MET和p-ERK1/2,并上调p 21和p 27,抑制HT29细胞的增殖;过表达NDRG2明显上调c-MET、p-ERK1/2,并诱导p 21和p 27的高表达,从而抑制HT29细胞的增殖。结论:NDRG2可以通过调节HGF/c-MET信号通路从而抑制结肠癌细胞HT29细胞的增殖能力。     

HGF及其c-MET受体在非小细胞肺癌中的研究进展

随着肿瘤分子生物学的飞速发展,分子靶向治疗已成为目前晚期肺癌治疗方法中最具前景的研究领域,因此分子靶点的研究也早已成为医学界关注的热点。近年来,研究发现HGF及其c-MET受体与非小细胞肺癌（non-small cell lung cancer,NSCLC）的发生、发展、组织学类型及预后密切相关。全文就HGF及其c-MET受体的结构、功能及其相关的靶向药物在NSCLC中的研究进展进行综述。     

HGF/c-Met信号传导通路与晚期非小细胞肺癌关系的研究进展

 肝细胞生长因子（hepatocyte growth factor,HGF）/c-Met信号传导通路在晚期非小细胞肺癌（non-small cell lung cancer,NSCLC）的发生、发展中起重要调控作用,并与表皮生长因子受体酪氨酸激酶抑制剂的继发性耐药密切相关。针对该通路的分子靶向治疗为晚期NSCLC提供了新的思路,现已成为近年研究的热点。本文就HGF/c-Met的结构、功能及其在晚期NSCLC中的治疗进展等作一综述。     

非小细胞肺癌中 HGF/c-Met 信号通路与 EGFR-TKI 获得性耐药的关系

表皮生长因子受体酪氨酸激酶抑制剂（EGFR-TKI）为首的靶向药物在晚期非小细胞肺癌患者治疗中取得巨大进展。然而,获得性耐药的出现是其不可避免的结果。肝细胞生长因子（HGF）／c-Met信号通路参与多种肿瘤细胞的形成、迁徙、血管生成等重要细胞进程。该信号通路的异常激活在EGFR-TKI 获得性耐药中发挥了重要作用。实验表明,HGF ／c-Met 信号通路抑制剂可使部分 EGFR-TKI获得性耐药患者临床获益。     

Wnt/β-catenin信号通路在白血病中的研究进展

Wnt/ β-catenin信号通路在胚胎发生和器官发育中发挥着重要作用.该信号通路与多种实体肿瘤的发生密切相关.新近研究发现,Wnt/β-catenin信号通路在多种白血病中异常激活,提示其可能参与了白血病的发生、发展.针对Wnt/β-catenin信号通路的靶向治疗可能成为白血病治疗的新方向.本文就Wnt/β-catenin信号通路在白血病中的研究进展作一综述.     

胰腺癌相关信号转导通路研究新进展

信号转导通路的研究是阐明疾病发生、发展机制的重要手段,针对信号转导系统的分子靶向治疗是当今医学界的热点研究领域。与胰腺癌相关的细胞信号通路包括：MAPK通路、WNT通路、Hedgehog（Hh）通路、STAT通路、PI3K/AKT通路、应激通路、炎症通路（Cox-2通路与Notch通路）、激素通路以及抗细胞增殖通路。这些信号通路,     

PI3K/Akt/mTOR信号通路抑制剂在乳腺癌中的研究进展

目的:总结PI3K/Akt/mTOR信号通路靶向治疗在乳腺癌中的研究进展.方法:以“PI3K/Akt/mTOR、信号通路和乳腺癌”等为关键词,检索2000-01-2011-06 PubMed、Ovid和Springer等数据库的相关文献.纳入标准:1)关于PI3K/Akt/mTOR信号通路的组成、功能特点;2)PI3K/Akt/mTOR信号通路与乳腺癌的关系研究;3)以PI3K/Akt/mTOR信号通路中关键分子为靶点的乳腺癌治疗.根据纳入标准,符合分析的文献40篇.结果:信号转导通路的异常是肿瘤发生、发展的重要步骤,PI3K/Akt/mTOR信号通路与人类多种肿瘤密切相关,其在肿瘤细胞的增殖、存活、抵抗凋亡、血管发生和转移以及对放化疗抵抗中发挥了重要作用.乳腺癌中常见PI3K/Akt/mTOR信号通路的异常激活,以此通路为靶点的药物已成为乳腺癌治疗的研究热点.结论:靶向PI3K/Akt/mTOR通路中关键分子的众多药物在乳腺癌开展了一系列相关的临床试验研究,一部分显示出较好的安全性和有效性.随着对PI3K/Akt/mTOR通路的分子生物学机制的深入研究,期待靶向此通路的抑制剂将会在乳腺癌治疗中发挥巨大的作用,进一步提高乳腺癌患者的疗效和改善预后.     

Hedgehog信号通路在胰腺癌中的研究进展

Hedgehog(HH)信号通路是一个信号级联放大反应,对大多数动物胚胎的正常发育至关重要,在成人组织中的异常激活能导致肿瘤的发生.研究发现,HH信号通路与胰腺胚胎发育密切相关,其传导异常可导致胰腺癌的发生.探讨HH信号通路在胰腺癌中的作用将为研究胰腺癌的发病机制和治疗方法提供新的思路.     

Hepatocyte growth-factor and its receptor C-met regulate both cell-growth and invasion of human pancreatic-cancer

Hepatocyte growth factor (HGF) has an important role not only in liver regeneration buy also in the development of cancer metastasis. It has been known that HGF and its receptor/c-MET are overexpressed in human pancreatic cancer in vivo, compared with the normal pancreas. To examine the propensity of pancreatic cancer to metastasize and its association with poor prognosis, we studied the effects of HGF and c-MET on pancreatic cancer cell growth and invasion in vitro. Dose-dependently, HGF promoted both the growth and invasiveness of pancreatic cancer cells that expressed c-MET; as a chemoattractant, the high gradient of HGF determined the direction of the invasiveness of the cells. No stimulant effect, however, was observed in cancer cells that did not express c-MET. These results suggest that HGF and c-MET may play important roles in human pancreatic cancer cell growth and invasion-metastatic potential.     

Foretinib inhibits angiogenesis,lymphangiogenesis and tumor growth of pancreatic cancer in vivo by decreasing VEGFR-2/3 and TIE-2 signaling

Foretinib, a multiple kinase inhibitor undergoing clinical trials, could suppress the activity of hepatocyte growth factor (HGF) receptor c-MET and vascular endothelial growth factor receptor-2 (VEGFR-2). In addition, Foretinib may inhibit two critical lymphangiogenic signaling receptors VEGFR-3 and TIE-2. However, the effect of Foretinib on lymphatic endothelial cells (LECs) in vitro and lymphangiogenesis in vivo is still unknown. We found Foretinib decreased basal- and HGF-induced c-MET activity at low concentrations. However, Foretinib only reduced the proliferation of pancreatic cancer cells at high concentration reflecting the intrinsic chemoresistance of pancreatic cancer cells. Foretinib inhibited VEGF-A, VEGF-C and Angiopoetin-2 (ANG-2)-stimulated tube formation and sprouting of LECs by reducing VEGFR-2, VEGFR-3 and TIE-2 activation and increased apoptosis of LECs. In xenograft animal study, Foretinib suppressed tumor growth by inhibiting proliferation, angiogenesis and lymphangiogenesis. Additionally, Foretinib inhibited angiogenesis and lymphangiogenesis more significantly and exhibited low detrimental effect in orthotopic animal study. Collectively, we suggested that Foretinib simultaneously inhibits cancer cells and LECs to reduce pancreatic tumor growth in vivo and demonstrated for the first time that Foretinib suppresses angiogenesis and lymphangiogenesis by blocking VEGFR-2/3 and TIE-2 signaling.     

Expression of hepatocyte growth factor and c-MET in skull base chordoma

BACKGROUND: Hepatocyte growth factor (HGF) is a multipotent cytokine that is mediated by its receptor, c-MET. HGF/c-MET contributes to tumor progression in many human malignancies; however, HGF/c-MET is inversely correlated with aggressive biologic behavior in other cancers. Conversely, to the authors' knowledge, little is known regarding the significance of HGF/c-MET expression in skull base chordoma. METHODS: Using immunohistochemical techniques, the authors investigated HGF/c-MET expression in 46 primary and 25 recurrent lesions, and compared it with the expression of proteinases and cell differentiation markers, proliferative ability, and other clinicopathologic parameters. RESULTS: c-MET was found to be expressed in 70.0% of primary and 88.0% of recurrent lesions. HGF expression was scarcely detected. Higher c-MET expression was found to be correlated with younger patient age. Lesions with a higher expression of low molecular weight cytokeratin (CAM5.2) demonstrated significantly higher c-MET scores in both primary and recurrent lesions compared with those with lower CAM5.2 expression. In recurrent lesions, higher c-MET expression was found to be associated with the scores of matrix metalloproteinase (MMP)-1, MMP-2, tissue inhibitor of matrix metalloproteinase-1, and urokinase plasminogen activator (uPA); however, only uPA was found to be correlated with higher c-MET expression in primary lesions. c-MET expression did not appear to be correlated with MIB-1 labeling index. Patients with higher c-MET expression were found to have longer survival. CONCLUSIONS: In the current study, c-MET expression was a common event, and was found to be correlated with CAM5.2 expression, younger patient age, and a favorable prognosis in patients with skull base chordoma. However, HGF/c-MET paracrine signaling also may contribute to its invasive ability, especially in recurrent lesions.     

HGF、c-MET及VEGF在非小细胞肺癌中的表达和意义

目的 探讨肝细胞生长因子(HGF)、肝细胞生长因子受体(c-MET)及血管内皮生长因子(VEGF)的表达与非小细胞肺癌临床病理的关系.方法 将组织标本分为原发灶组(357例)和正常对照组(68例),分别采用免疫组织化学方法检测各组标本中HGF、c-MET及VEGF的表达情况.结果 非小细胞肺癌原发灶组织和正常组织中HGF表达阳性率分别为51.26％ (183/357)和10.29％ (7/68),两组之间差异有统计学意义(P＜0.05);非小细胞肺癌原发灶组织和正常组织中c-MET表达阳性率分别为60.22％ (215/357)和14.71％(10/68),两组间差异有统计学意义(P＜0.05);非小细胞肺癌原发灶组织和正常组织中VEGF表达阳性率分别为45.38％(162/357)和11.76％(8/68),两组间差异有统计学意义(P＜0.05);HGF阳性表达率与肿瘤组织分化程度及临床分期无关(P＞0.05),c-MET及VEGF阳性表达率与肿瘤组织分化程度及临床分期相关(P＜0.05).结论 HGF和c-MET、VEGF可能共同参与了非小细胞肺癌的发生和发展,c-MET和VEGF或可作为预测非小细胞肺癌患者预后的标记物.     

Nuclear translocation of the receptor tyrosine kinase c-MET reduces the treatment efficacies of olaparib and gemcitabine in pancreatic ductal adenocarcinoma cells

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer that lack effective therapeutic strategies. The response rate of PDAC for treatment with gemcitabine, a current first-line chemotherapeutic for this tumor, is lower than 20%. Identifying key targetable molecules that mediate gemcitabine resistance and developing novel strategies for precision PDAC medicine are urgently needed. Most PDACs have either intratumoral hypoxia or high reactive oxygen species (ROS) production; cytotoxic chemotherapy can elevate ROS production in PDACs. Although excessive ROS production leads to oxidative damage of macromolecules such as DNA, pancreatic cancer cells can survive high DNA damage stress levels. Therefore, identifying molecular mechanisms of overcoming ROS-induced stress in pancreatic cancer cells is important for developing novel therapeutic strategies. ROS-induced DNA damage is predominantly repaired via poly (ADP-ribose) polymerase 1 (PARP1)-mediated DNA repair mechanisms. A recent clinical trial reported that PARP inhibitors are effective in treating pancreatic patients carrying BRCA mutations. However, only less than 10% of pancreatic cancer patients bearing BRCA mutated tumors. Activation of the receptor tyrosine kinase c-MET positively correlates with poor prognosis for PDAC, and our previous study showed that nuclear c-MET can phosphorylate PARP1 at tyrosine 907 under ROS stimulation to promote DNA repair. As described herein, we proposed to expand PARP inhibitor-targeted therapy to more pancreatic cancer patients regardless of BRCA mutation status by combining olaparib, a PARP inhibitor, with c-MET inhibitors as we demonstrated in our previous studies in breast cancer. In this prospective study, we found that ROS-inducing chemotherapeutic drugs such as gemcitabine and doxorubicin stimulated nuclear accumulation of c-MET in BxPC-3 and L3.6pl pancreatic cancer cells. We further showed that combining a c-MET inhibitor with gemcitabine or a PARP inhibitor induced more DNA damage than monotherapy did. Moreover, we demonstrated the synergistic antitumor effects of c-MET inhibitors combined with a PARP inhibitor or gemcitabine in eliminating pancreatic cancer cells. These data suggested that accumulation of ROS in pancreatic cancer cells promotes nuclear localization of c-MET, resulting in resistance to both chemotherapy and PARP inhibitors. Our findings suggest that combining c-MET inhibitors with PARP inhibitors or gemcitabine is a novel, rational therapeutic strategy for advanced pancreatic cancer.     

Hepatocyte growth factor inhibition: a novel therapeutic approach in pancreatic cancer

Background:

Pancreatic stellate cells (PSCs, which produce the stroma of pancreatic cancer (PC)) interact with cancer cells to facilitate PC growth. A candidate growth factor pathway that may mediate this interaction is the HGF–c-MET pathway.

Methods:

Effects of HGF inhibition (using a neutralising antibody AMG102) alone or in combination with gemcitabine were assessed (i) in vivo using an orthotopic model of PC, and (ii) in vitro using cultured PC cells (AsPC-1) and human PSCs.

Results:

We have shown that human PSCs (hPSCs) secrete HGF but do not express the receptor c-MET, which is present predominantly on cancer cells. HGF inhibition was as effective as standard chemotherapy in inhibiting local tumour growth but was significantly more effective than gemcitabine in reducing tumour angiogenesis and metastasis. HGF inhibition has resulted in reduced metastasis; however, interestingly this antimetastatic effect was lost when combined with gemcitabine. This suggests that gemcitabine treatment selects out a subpopulation of cancer cells with increased epithelial–mesenchymal transition (EMT) and stem-cell characteristics, as supported by our findings of increased expression of EMT and stem-cell markers in tumour sections from our animal model. In vitro studies showed that hPSC secretions induced proliferation and migration, but inhibited apoptosis, of cancer cells. These effects were countered by pretreatment of hPSC secretions with a HGF-neutralising antibody but not by gemcitabine, indicating a key role for HGF in PSC–PC interactions.

Conclusions:

Our studies suggest that targeted therapy to inhibit stromal–tumour interactions mediated by the HGF–c-MET pathway may represent a novel therapeutic approach in PC that will require careful modelling for optimal integration with existing treatment modalities.     

Radiation stimulates HGF receptor/c-Met expression that leads to amplifying cellular response to HGF stimulation via upregulated receptor tyrosine phosphorylation and MAP kinase activity in pancreatic cancer cells

Hepatocyte growth factor (HGF) is a stromal-derived cytokine that plays a crucial role in invasion and metastasis of tumor cells through the interaction with HGF receptor, c-Met, which is frequently overexpressed in pancreatic cancer. The present study was designed to investigate the change in HGF receptor and HGF-mediated signaling after irradiation in pancreatic cancer cells. Six cell lines from human pancreatic cancer were included in the study. Gamma-radiation was used for irradiation treatment. The changes in expression levels of c-Met were evaluated by immunoblot and confirmed morphologically by indirect immunofluorescence staining. Whether the resultant alteration in c-Met would cascade as biologically usable signals upon HGF ligation was traced by receptor tyrosine phosphorylation analysis and mitogen activated protein kinase (MAP kinase or MAPK) activity assay. The various biological responses to HGF (including cell proliferation, cell scattering, migration and invasion) were evaluated as well. We also used a 4-kringle antagonist of HGF, NK4, to block the HGF/c-Met signaling pathway. Both immunoblot and immunofluorescent analysis showed moderate increased expression of c-Met in 3 of 6 pancreatic cancer cell lines after irradiation. The actions seemed to be dose-responsible, which began at 3 hr and reached its peak value at 24 hr following irradiation. The radiation-increased expression of c-Met could transform into magnifying receptor tyrosine phosphorylation reaction and MAP kinase activity once the ligand was added, fairly corresponding with alteration in the receptor. Sequentially, the cellular responses to HGF, including scattering and invasion but not proliferation, were enhanced. Also, in the presence of HGF, the elevated receptor could help to recover the radiation-compromised cell migration. A recombinant HGF antagonist, NK4 could effectively block these aberrant effects activated by irradiation both in molecular and cellular levels, thus suggesting the deep involvement of the c-Met/HGF pathway in the enhanced malignant potential after irradiation. These results suggest that radiation may promote HGF-induced malignant biological behaviors of certain pancreatic cancer cells through the up-regulated HGF/c-Met signal pathway. Selectively targeted blockade of the HGF/c-Met pathway could help to abolish the enforced malignant behavior of tumor cells by irradiation and therefore may improve the efficacy of radiotherapy for pancreatic cancer.     

Downstream signalling and specific inhibition of c-MET/HGF pathway in small cell lung cancer: implications for tumour invasion

The c-MET receptor can be overexpressed, amplified, or mutated in solid tumours including small cell lung cancer (SCLC). In c-MET-overexpressing SCLC cell line NCI-H69, hepatocyte growth factor (HGF) dramatically induced c-MET phosphorylation at phosphoepitopes pY1230/1234/1235 (catalytic tyrosine kinase), pY1003 (juxtamembrane), and also of paxillin at pY31 (CRKL-binding site). We utilised a global proteomics phosphoantibody array approach to identify further c-MET/HGF signal transduction intermediates in SCLC. Strong HGF induction of specific phosphorylation sites in phosphoproteins involved in c-MET/HGF signal transduction was detected, namely adducin-alpha [S724], adducin-gamma [S662], CREB [S133], ERK1 [T185/Y187], ERK1/2 [T202/Y204], ERK2 [T185/Y187], MAPKK (MEK) 1/2 [S221/S225], MAPKK (MEK) 3/6 [S189/S207], RB [S612], RB1 [S780], JNK [T183/Y185], STAT3 [S727], focal adhesion kinase (FAK) [Y576/S722/S910], p38alpha-MAPK [T180/Y182], and AKT1[S473] and [T308]. Conversely, inhibition of phosphorylation by HGF in protein kinase C (PKC), protein kinase R (PKR), and also CDK1 was identified. Phosphoantibody-based immunohistochemical analysis of SCLC tumour tissue and microarray established the role of c-MET in SCLC biology. This supports a role of c-MET activation in tumour invasive front in the tumour progression and invasion involving FAK and AKT downstream. The c-MET serves as an attractive therapeutic target in SCLC, as shown through small interfering RNA (siRNA) and selective prototype c-MET inhibitor SU11274, inhibiting the phosphorylation of c-MET itself and its downstream molecules such as AKT, S6 kinase, and ERK1/2. Investigation of mechanisms of invasion and, ultimately, metastasis in SCLC would be very useful with these signal transduction molecules.     

Crizotinib Exhibits Antitumor Activity by Targeting ALK Signaling not c-MET in Pancreatic Cancer

Crizotinib, a c-MET/ALK inhibitor, has exhibited antitumor efficacy in different types of cancers. However, studies regarding Crizotinib in pancreatic cancer have been limited. Thus, we investigated the effect of Crizotinib on pancreatic cancer and its mechanism of action. Crizotinib strongly suppressed the growth and proliferation of pancreatic cancer cells in a dose-dependent manner. Also, it induced apoptosis by modulating its related factors. In the study, with regard to the mechanism of action, Crizotinib did not inhibit c-MET expression on pancreatic cancer cells; instead, it specifically inhibited the activity of ALK, which was identified to be highly expressed on various pancreatic cancer cells and tissues in our study. In 42 different receptor tyrosine kinase (RTKs) array, Crizotinib also strongly inhibited the expression of activated ALK in pancreatic cancer cells, modulating its downstream mediators such as STAT3, AKT, and ERK. Furthermore, Crizotinib inhibited angiogenesis in a mouse Matrigel plug assay as well as the progression of tumor growth in a mouse xenograft model. Taken together, our investigation shows that Crizotinib inhibits the ALK signaling pathway in pancreatic cancer, resulting in cell growth/angiogenesis inhibition and apoptosis induction. We suggest that Crizotinib might be used as a novel therapeutic drug for treating pancreatic cancer.     

MetMAb, the one-armed 5D5 anti-c-Met antibody, inhibits orthotopic pancreatic tumor growth and improves survival

The hepatocyte growth factor (HGF) and its receptor, c-Met, have been implicated in driving proliferation, invasion, and poor prognosis in pancreatic cancer. Here, we investigated the expression of HGF and c-Met in primary pancreatic cancers and described in vitro and in vivo models in which MetMAb, a monovalent antibody against c-Met, was evaluated. First, expression of HGF and MET mRNA was analyzed in 59 primary pancreatic cancers and 51 normal samples, showing that both factors are highly expressed in pancreatic cancer. We next examined HGF responsiveness in pancreatic cancer lines to select lines that proliferate in response to HGF. Based on these studies, two lines were selected for further in vivo model development: BxPC-3 (c-Met(+), HGF(-)) and KP4 (c-Met(+), HGF(+)) cells. As BxPC-3 cells are responsive to exogenous HGF, s.c. tumor xenografts were grown in a paracrine manner with purified human HGF provided by osmotic pumps, wherein MetMAb treatment significantly inhibited tumor growth. KP4 cells are autocrine for HGF and c-Met, and MetMAb strongly inhibited s.c. tumor growth. To better model pancreatic cancer and to enable long-term survival studies, an orthotopic model of KP4 was established. MetMAb significantly inhibited orthotopic KP4 tumor growth in 4-week studies monitored by ultrasound and also improved survival in 90-day studies. MetMAb significantly reduced c-Met phosphorylation in orthotopic KP4 tumors with a concomitant decrease in Ki-67 staining. These data suggest that the HGF/c-Met axis plays an important role in the progression of pancreatic cancer and that targeting c-Met therein may have therapeutic value.