质子泵抑制剂泮托拉唑钠抑制肺癌细胞上皮间质转化和顺铂耐药的机制研究

目的:探索泮托拉唑钠(pantoprazole sodium,PPZ)抑制肺癌细胞上皮间质转化和顺铂耐药的分子机制。方法:通过MTT法、划痕修复实验、Transwell实验和Western blot法比较A549细胞与A549/DDP细胞之间的形态、侵袭能力、迁移能力、药物敏感性和蛋白表达差异,观察泮托拉唑钠对A549/DDP细胞的形态、侵袭能力、迁移能力、药物敏感性和蛋白表达的影响。结果:与A549细胞比较,A549/DDP细胞存在高侵袭能力、高迁移能力、对顺铂耐药、具有间质表型和c-Met/AKT/m TOR通路活化等特点,泮托拉唑钠可抑制A549/DDP细胞的侵袭和迁移能力,逆转其耐药及间质表型,抑制c-Met/AKT/m TOR通路的活化。应用c-Met抑制剂SU11274、PI3K抑制剂LY294002和m TOR抑制剂rapamycin处理A549/DDP细胞后的作用与泮托拉唑钠相似。结论:泮托拉唑钠抑制cMet/AKT/m TOR信号通路抑制肺癌细胞侵袭、迁移、上皮间质转化和顺铂耐药。     

姜黄素逆转HGF诱导PC9细胞对吉非替尼的耐药

目的:探索姜黄素逆转肝细胞生长因子(HGF)诱导的肺癌细胞吉非替尼耐药性的分子机制。方法:利用MTT实验、划痕修复实验和Western blot观察HGF、吉非替尼和姜黄素对PC9细胞药物敏感性、迁移能力、上皮间质转化和相关信号通路的影响.结果:HGF可显著降低PC9细胞对吉非替尼的敏感性,而姜黄素可显著逆转HGF诱导的PC9细胞对吉非替尼的耐药性。HGF还可诱导PC9细胞发生迁移及上皮间质转化,激活c-Met/AKT/mTOR通路,单独吉非替尼不能逆转HGF诱导的迁移、上皮间质转化及c-Met/AKT/mTOR通路活化,而吉非替尼联合姜黄素可抑制HGF诱导的c-Met/AKT/mTOR通路活化并逆转PC9细胞的迁移和上皮间质转化。结论:姜黄素抑制HGF诱导的PC9细胞吉非替尼耐药性可能是通过逆转上皮间质转化和抑制c-Met/AKT/mTOR通路实现的。     

姜黄素下调PI3K/AKT/mTOR通路抑制人肝癌细胞系增殖

目的观察姜黄素对体外培养人肝癌细胞系HL-7702增殖的影响,并探讨其作用机制。方法体外培养HL-7702细胞,不同浓度的姜黄素(0、10、20、40和80μmol/L)处理48 h。PI3K/AKT抑制剂LY294002联合姜黄素处理细胞。分别用MTT法检测细胞增殖,用Western blot法检测细胞内PI3K、AKT、m TOR、Bax、Bcl-2及活化的caspase-3的蛋白含量。结果姜黄素可以浓度依赖性的抑制HL-7702细胞增殖,增加细胞中PI3K、AKT和m TOR的磷酸化水平(P0.05)。姜黄素可诱导HL-7702细胞凋亡,增加Bax和活化的caspase-3的含量(P0.05),减少Bcl-2的含量(P0.05)。LY294002与姜黄素联用后,姜黄素对细胞增殖及凋亡无明显作用。结论姜黄素可抑制人肝癌细胞系HL-7702增殖,诱导细胞凋亡,作用机制可能与其下调PIK/AKT/m TOR信号通路的活性有关。     

HGF/c-Met促进大鼠骨髓内皮祖细胞迁移能力

目的探讨肝细胞生长因子(HGF)及其受体c-Met对大鼠骨髓内皮祖细胞(EPCs)迁移能力的影响及其机制。方法提取、培养和鉴定大鼠骨髓EPCs;重组腺病毒载体介导c-Met基因转染EPCs,用real-time PCR、Western blot和CCK8分别检测c-Met的表达和细胞增殖;分别用0、5、10、20和50 ng/m L HGF处理Ad-c-Met-EPCs,并通过Transwell迁移系统检测Ad-c-Met-EPCs的迁移能力;选取适宜浓度的HGF处理EPCs、Ad-GFP-EPCs和Ad-c-MetEPCs,并设置PBS对照组和磷脂酰肌醇3-激酶抑制剂LY294002组(同时加入HGF和10 g/L的LY294002),通过Transwell迁移系统和Western blot分别检测各组细胞的迁移能力、Akt和P-Akt的表达。结果 1)Ad-c-Met-EPCs中c-Met基因与蛋白均为高表达(P0.05)。2)c-Met基因对EPCs的增殖无明显影响。3)HGF在0~50 ng/m L范围内呈浓度依赖性促进Ad-c-Met-EPCs迁移。4)HGF+Ad-c-Met-EPCs组的迁移能力和P-Akt的表达显著高于对照组、HGF+EPCs组、HGF+Ad-GFP-EPCs组和HGF+LY294002+Ad-c-Met-EPCs组(P0.05)。结论 HGF/c-Met能够显著提高EPCs的迁移能力;HGF/c-Met可能通过PI3K/Akt信号通路促进EPCs的迁移。     

肺炎衣原体感染通过PI3K通路诱导血管内皮细胞迁移

目的:研究肺炎衣原体感染对血管内皮细胞迁移的影响及其相关分子机制。方法:创伤修复实验与Transwell实验观察肺炎衣原体感染的血管内皮细胞迁移情况,RT-PCR与ELISA法分别检测PI3K mRNA表达与酶活性。结果:肺炎衣原体感染以时间依赖方式明显促进人内皮细胞素ECV304细胞迁移,且可以显著增强PI3K mRNA表达与酶活性;PI3K特异性抑制剂LY294002可有效抑制肺炎衣原体感染引起的上述变化。结论:肺炎衣原体感染可诱导血管内皮细胞迁移,其机制可能与激活PI3K信号转导通路有关。     

APS通过PI3K/AKT信号通路促进神经干细胞增殖

目的观察APS是否通过PI3K/AKT信号通路促进神经干细胞增殖。方法将神经干细胞,随机分为对照组、APS(5%)组、APS(5%)+LY294002组和LY294002组,用间接免疫荧光法检测Nestin和Brdu;CCK-8检测细胞增殖;Elisa检测VEGF、FLK-1含量;Western blot法检测FLK-1、PI3K、P-Akt蛋白表达。结果 APS可以提高LY294002干预后神经干细胞增殖(P0.05),提高VEGF、FLK-1含量(P0.05),提高FLK-1、PI3K、P-Akt蛋白表达(P0.05)。结论 APS可能通过促进Akt磷酸化,活化PI3K/AKT信号通路,调节PI3K/AKT信号通路下游靶基因,促进神经干细胞增殖。     

Akt、ERK1/2活化在脑源性神经营养因子促血管新生中的作用

目的： 探讨脑源性神经营养因子(BDNF) 促进血管新生的作用及其参与的信号通路,为抗肿瘤血管生成的研究提供新的实验依据。 方法: 以人脐静脉内皮细胞为对象,采用Western 印迹方法检测细胞内磷酸化Akt、ERK1/2蛋白质的表达； 采用Transwell小室迁移实验、管腔形成实验评价体外内皮细胞血管新生的能力，MTT法检测内皮细胞增殖 活性，FITC-Annexin-Ⅴ/PI双染流式细胞术分析细胞凋亡。 结果: BDNF以时间依赖性方式激活PI3K/Akt 和MEK1/ERK信号通路。分别应用PI3K激酶抑制剂Ly294002、 MEK1激酶抑制剂PD98059可以明显阻断BDNF对PI3K/Akt、MEK1/ERK信号通路的激活。100 μg/L 的BDNF体 外促内皮细胞血管新生能力与 25 μg/L 血管内皮生长因子（VEGF）相当， 其中BDNF诱导的细胞迁移分 别被Ly294002和PD98059阻断，其抑制率分别约为74%和36%；同样，Ly294002、PD98059可部分阻断BDNF诱 导的小管形成效应，其阻断率分别约57%和37%；而BDNF的促增殖效应仅被PD98059拮抗，抑制凋亡效应仅受Ly294002影响。 结论: BDNF在体外有促血管新生的作用。PI3K/Akt 和MEK1/ERK信号通路以不同机制共同调节这一过程,其中PI3K/Akt信号通路起着更为重要的调节作用。     

肝细胞生长因子促进HeLa细胞上皮间质转化

目的探讨肝细胞生长因子对宫颈癌He La细胞上皮间质转化的影响。方法以不同浓度的HGF(0、5、10、20和40 ng/m L)处理细胞24 h或20 ng/m L肝细胞生长因子(HGF)处理细胞不同时间(0、6、12、24和48 h),MTT检测细胞活力;用HGF(20 ng/m L)处理细胞24 h,倒置显微镜观察He La细胞形态,划痕实验检测细胞的迁移及Transwell实验检测细胞的侵袭能力。Western blot检测上皮细胞的标志蛋白E-Cadherin及转录因子snail和间质细胞的表面标志蛋白vimentin的表达,HGF/c-Met信号通路分子的表达情况。结果 HGF促进He La细胞增殖,其中以20 ng/m L或20 ng/m L处理24 h生存率达到最高峰;此外,HGF可以促进He La细胞迁移、侵袭及上皮间质转化,并促进c-Met磷酸化,并且激活p-ERK、p-AKT以及促进snail的蛋白表达(P0.05或P0.01)。结论 HGF可以促进He La细胞上皮间质转化,其机制可能是通过HGF/c-Met/MAPK或HGF/c-Met/AKT通路上调snail表达,进而调控E-cadherin或vimentin表达有关。     

姜黄素抑制ox-LDL诱导HUVECs凋亡

目的研究姜黄素对氧化低密度脂蛋白(ox-LDL)诱导的人脐静脉内皮细胞(HUVECs)凋亡的保护作用及其可能机制。方法体外培养HUVECs,实验分为:对照组、ox-LDL组、ox-LDL加内质网应激(ERS)抑制剂PBA组、姜黄素组、ox-LDL加姜黄素组和ox-LDL加姜黄素加PI3K抑制剂LY294002组。CCK-8法检测细胞存活率;流式细胞仪检测细胞凋亡;激光共聚焦显微镜观察活化转录因子6(ATF6)转位;Western bolt检测ERS相关蛋白:糖调节蛋白78(GRP78)、蛋白激酶样内质网激酶(PERK)和肌醇激酶-1(IRE-1)以及相关通路蛋白:LOX-1、AKT和p-AKT的表达。结果与对照组相比,ox-LDL可增加细胞凋亡,提高ERS相关蛋白的表达(P0.01),促使ATF6向核内转位,以及提高LOX-1(P0.01)和降低p-AKT的表达(P0.01);与ox-LDL组相比,PBA可抑制ox-LDL诱导的细胞凋亡(P0.01),姜黄素可抑制ox-LDL诱导的ERS相关蛋白和LOX-1的表达(P0.01),ATF6的核转位,内皮细胞的凋亡(P0.01),同时它还可提高ox-LDL引起的p-AKT表达下调(P0.01);LY294002可部分削弱姜黄素抑制ox-LDL诱导ERS相关蛋白表达的作用(P0.05)。结论姜黄素可降低ox-LDL诱导HUVECs的凋亡,其可能机制是通过抑制LOX-1的表达和激活AKT通路减轻细胞ERS来实现的。     

Tpr-Met转化的Ba/F3稳定株的构建

目的:建立一种可用于高通量筛选c-Met抑制剂的细胞模型.方法:采用电转染将Tpr-Met表达载体导入Ba/F3细胞中并筛选出能够稳定表达Tpr-Met的细胞株.而后对这种稳定株的白细胞介素3(IL-3)非依赖性增殖、Tpr-Met的表达及下游通路的活化、c-Met抑制剂SUl1274对细胞增殖和信号通路的抑制作用进行全面评价.通过酶标仪检测细胞MTS吸光度值判断细胞的增殖水平,通过Western blot法检测Tpr-Met的表达及下游通路的活化、c-Met抑制剂SU11274对细胞信号通路的抑制作用.结果:获得稳定表达Tpr-Met的Ba/F3细胞株,该细胞株呈现IL-3非依赖性生长；能够表达持续活化的Tpr-Met；下游信号通路中关键分子Erk的磷酸化水平显著提升；c-Met特异性抑制剂SU11274通过抑制Tpr-Met磷酸化抑制下游信号通路的活化并抑制稳定株细胞增殖.结论:成功构建了Tpr-Met转化的Ba/F3细胞株.     

HGF/c-Met Signaling Mediated Mesenchymal Stem Cell-induced Liver Recovery in Intestinal Ischemia Reperfusion Model

Purpose: Liver injury triggered by intestinal ischemia-reperfusion (IIR) usually presage multiorgan dysfunction and death in patients. Recent studies suggest mesenchymal stem cells (MSCs) possess a protective potential against organ damage. Since relative evidence is insufficient and the mechanism is not well understood, we investigated the effect of hepatocyte growth factor c-Met signaling (HGF/c-Met) on recruitment of MSCs and subsequent protection against liver injury triggered by IIR in a rat model.Methods: IIR models were built as rats were subjected to 75 min of superior mesenteric artery occlusion and subsequent 4 h reperfusion. Either of pure MSCs and MSCs pretreated with HGF or SU11274 (c-Met inhibitor) were injected into rat models. Biochemical and pathologic alterations of liver in IIR model were measured to evaluate the therapeutic effect of MSCs and drug treatment. Concurrently, the effect of HGF and SU11274 on c-Met and phosphorylated Met expression in MSCs and MSCs migration were assessed in in vitro experiment.Results: IIR-induced liver injury was manifested by significant increase in serum ALT, AST and HGF levels as well as pathological change. MSCs with highly c-Met expression ameliorated the increase of serum transaminase levels and hepatic histopathological change, while SU11274 weaken these effects. HGF upregulated c-Met and phosphorylated Met expression in MSCs and enhanced its liver protection effect. Transwell assays demonstrated HGF promoted MSCs migration, which was blocked by SU11274.Conclusions: HGF/c-Met signaling pathway plays an essential role in the homing of MSCs towards injured liver triggered by intestinal ischemia-reperfusion, and then mediates MSC-induced liver repair.     

Activation of the PI3K/Akt/mTOR/p70S6K Pathway is Involved in S100A4-induced Viability and Migration in Colorectal Cancer Cells

The S100 protein family member S100A4 regulates various cellular functions. Previous studies have shown that elevated expression of S100A4 is associated with progression and metastasis of colorectal cancer (CRC). However, little is known about whether and how S100A4 contributes to CRC development. In our present study, the elevated expression of S100A4 in CRC tissues compared to matched adjacent normal tissues was confirmed by immunohistochemistry, semi-quantitative RT-PCR and Western blot. Adenovirus-mediated S100A4 overexpression obviously enhanced viability and migration of CRC cells, which was detected by MTT assay and transwell assay, respectively. Additionally, S100A4 overexpression increased the phosphorylation levels of Akt, mTOR and p70S6K. These effects of S100A4 were abolished by treatment with either the specific PI3K/Akt inhibitor {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002, or the specific mTOR/p70S6K inhibitor rapamycin. Furthermore, overexpression of S100A4 resulted in upregulation of VEGF and downregulation of E-cadherin, which were strongly reversed by either {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 or rapamycin. Altogether, our results demonstrate that activation of the PI3K/Akt/mTOR/p70S6K signaling pathway is involved in S100A4-induced viability, migration, upregulation of VEGF and downregulation of E-cadherin in CRC cells.     

榄香烯通过c-Met信号通路逆转由肝细胞生长因子诱导的吉非替尼耐药作用

目的:研究肝细胞生长因子(hepatocyte growth factor,HGF)诱导肺癌PC-9细胞对吉非替尼耐药的作用,并探讨榄香烯逆转此耐药作用的可能机制。方法:应用不同浓度的吉非替尼和榄香烯单独或联合作用于HGF诱导的PC-9细胞株。MTT法检测细胞活力,并计算吉非替尼的半数抑制浓度(half maximal inhibitory concentration,IC50);Transwell小室实验检测榄香烯对HGF诱导的吉非替尼耐药PC-9细胞侵袭能力的影响;Western blot检测PC-9细胞中c-Met、AKT及其磷酸化蛋白的水平。结果:榄香烯可以显著抑制肺癌PC-9细胞的活力(P0.05),随着药物剂量的增加,榄香烯对PC-9细胞的生长抑制率显著上升,在给药24 h后,其IC50为169.31 mg/L。肺癌PC-9细胞对吉非替尼敏感,随着吉非替尼浓度的增加,其对PC-9细胞生长的抑制作用不断增强,IC50为0.30μmol/L;外源性HGF(50μg/L)对肺癌PC-9细胞的生长有明显的促进作用,并诱导吉非替尼耐药。同时,使用cMet抑制剂SU11274联合吉非替尼作用于HGF诱导的PC-9细胞时,其存活率比吉非替尼单独作用于HGF诱导的PC-9细胞明显降低(P0.05)。Transwell小室结果显示,与对照组相比,HGF能显著提高肺癌PC-9细胞的侵袭能力;与HGF联合吉非替尼组相比,榄香烯、HGF联合吉非替尼作用能明显抑制肺癌PC-9细胞的侵袭能力。Western blot结果显示,与对照组相比,HGF可显著上调p-Met和p-AKT的蛋白水平;与HGF联合吉非替尼组相比,榄香烯、HGF联合吉非替尼作用能明显下调p-Met和p-AKT的蛋白水平(P0.01)。结论:榄香烯可逆转HGF诱导的肺癌PC-9细胞对吉非替尼耐药,其机制可能与抑制HGF活化的c-Met及其下游信号通路有关。     

Hepatocyte growth factor and c-Met expression in pericytes: implications for atherosclerotic plaque development

Intraplaque neovascularization contributes to the progression of atherosclerosis. Our aim is to understand the mobilization of cells and factors involved in this process. We investigated the localization of hepatocyte growth factor (HGF) and its receptor, c-Met, in human atherosclerotic plaques, together with the effects of HGF on pericyte migration in vitro. Atherosclerotic femoral arterial segments were collected and analysed from 13 subjects who were undergoing lower limb amputation. Pericytes were identified in human lesions using a 3G5 antibody. Immunohistochemical analysis localized HGF mainly around microvessels, in association with some, but not all, CD31-positive endothelial cells. c-Met expression was mainly associated with smooth muscle cells and pericytes, around some, but not all, microvessels within the atherosclerotic lesions; no detection was apparent in normal internal mammary arteries. Using RT-PCR, we demonstrated expression of HGF and c-Met in a rat pericyte cell-line, TR-PCT1, and in primary pericytes. HGF treatment of TR-PCT1 cells induced their migration, but not their proliferation, in a dose-dependent manner (10-100 ng/ml, p<0.01), an effect mediated by activation of the serine/threonine kinase Akt, shown by western blot analysis. Treating the cells with the PI3K inhibitors Wortmannin (0.1 microM) or LY294002 (10 microM) abolished these effects. This work demonstrates the expression of c-Met and HGF in human atherosclerotic arteries, in association with SM-actin-positive cells and CD-31-positive cells, respectively. HGF induces pericyte migration via PI3-kinase and Akt activation in vitro. HGF and c-Met may be involved in neovascularization during plaque development, and may recruit pericytes to neovessels. Since pericytes are thought to mechanically stabilize new blood vessels, these factors may function to protect against haemorrhage.     

The proangiogenic phenotype of human tumor-derived endothelial cells depends on thrombospondin-1 downregulation via phosphatidylinositol 3-kinase/Akt pathway

umor-derived endothelial cells (TEC) display increased survival and angiogenic properties in respect to normal endothelial cells. The aim of this study was to investigate the mechanism potentially involved in TEC proangiogenic phenotype. We found that thrombospondin-1 (TSP-1), a potent physiological inhibitor of angiogenesis, was significantly reduced in TEC in respect to normal endothelial cells. This reduction was confirmed by immunofluorescence in the intratumor vessels of clear cell renal carcinomas. As TEC were shown to display a basal upregulation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, we evaluated the possible regulation of TSP-1 by this pathway by using LY294002 and wortmannin, the PI3K inhibitors, and rapamycin, the mammalian target of rapamycin (mTOR) inhibitor. In addition, we developed negative dominant TEC for Akt. TSP-1 production by TEC was enhanced by the treatment with LY294002 and wortmannin and with rapamycin, suggesting a negative regulation of TSP-1 expression by the PI3K/Akt/mTOR pathway. In addition, downregulation of Akt activation in negative dominant Akt TEC enhanced TSP-1 expression and release. Administration of exogenous TSP-1 to TEC reduced their proangiogenic properties in vitro and in vivo. In parallel, blockade of TSP-1 with an anti-TSP-1 antibody in negative dominant Akt TEC restored their proangiogenic phenotype to levels similar to wild-type TEC. In conclusion, these results indicate that the upregulation of the PI3K/Akt/mTOR pathway is responsible for the inhibition of TSP-1 synthesis which is critical in determining the proangiogenic phenotype of TEC. Strategies aimed to inhibit the PI3K/Akt/mTOR pathway may restore a normal quiescent endothelial phenotype in TEC by promoting TSP-1 production.     

Activation of the phosphatidylinositol 3'-kinase/AKT pathway in neuroblastoma and its regulation by thioredoxin 1

Neuroblastoma is a malignant pediatric tumor with poor survival. The phosphatidylinositol 3'-kinase/AKT pathway is a crucial regulator of cellular processes including apoptosis. Thioredoxin 1, an inhibitor of tumor-suppressor phosphatase and tensin homolog, is overexpressed in many tumors. The objective of this study was to explore phosphatidylinositol 3'-kinase/AKT pathway activation and regulation by thioredoxin 1 to identify potential therapeutic targets. Immunohistochemical analysis was done on tissue microarrays from tumor samples of 101 patients, using antibodies against phosphatidylinositol 3'-kinase, AKT, activated AKT, phosphatase and tensin homolog, phosphorylated phosphatase and tensin homolog, thioredoxin 1, epidermal growth factor receptor, vascular endothelial growth factor and receptors (vascular endothelial growth factor 1 and vascular endothelial growth receptor 2), platelet-derived growth factor receptors, insulin-like growth factor 1 receptor, neurotrophic tyrosine kinase receptor type 2, phosphorylated 70-kd S6 protein kinase, 4E-binding protein 1, and phosphorylated mammalian target of rapamycin. Using 3 neuroblastoma cell lines, we investigated cell viability with AKT-specific inhibitors (LY294002, RAD001) and thioredoxin 1 alone or in combination. We found activated AKT and AKT expressed in 97% and 98%, respectively, of neuroblastomas, despite a high expression of phosphatase and tensin homolog correlated with thioredoxin 1. AKT expression was greater in metastatic than primary tumors. Insulin-like growth factor 1 receptor, tyrosine kinase receptor type 2, vascular endothelial growth receptor 1, and downstream phosphorylated 70-kd S6 protein kinase were correlated with activated AKT. LY294002 and RAD001 significantly reduced AKT activity and cell viability and induced a G(1) cell cycle arrest. Thioredoxin 1 decreased cytotoxicity of AKT inhibitors and doxorubicin, up-regulated AKT activation, and induced cell growth. Thus, vascular endothelial growth receptor 1, tyrosine kinase receptor type 2, insulin-like growth factor 1 receptor, and thioredoxin 1 emerged as preferentially committed to phosphatidylinositol 3'-kinase/AKT pathway activation as observed in neuroblastoma. Thioredoxin 1 is a potential target for therapeutic intervention.     

Co-expression of VEGF, c-Met and HGF/SF in secondary pleural tumors

Tumor angiogenesis is influenced by a large number of angiogenic factors among which vascular endothelial growth factor (VEGF) is one of the most important cytokines. Together with hepatocyte growth factor/scatter factor (HGF/SF), c-Met receptor forms a paracrine signaling system. The aim was to study the characterization of the proteins, VEGF, c-Met and HGF/SF with expression pattern and possible co-expression in secondary pleural tumors. Biopsy specimens of the pleural region from 70 patients were chosen and analyzed using immunohistochemistry and in situ hybridization. In the investigated tumors, a marked intracytoplasmic expression, sometimes over-expression of VEGF, c-Met and HGF/SF was detected. This expression was not connected to certain tumor types or a certain histogenetic origin of the tumor. These results indicate a role of these factors in angiogenesis. The synthesis of VEGF and c-Met within the tumor cells was established by in situ hybridization. There was a significant co-expression of VEGF and c-Met/HGF. Thus, autocrine stimulation of these angio-genetically effective systems may be present here. Importantly, the autocrine mechanism between over-expressed c-Met and HGF/SF in malignant tumors, already preferred by other authors, with demonstration of the proteins in the same tumor cells, has to be assumed in the process of pleural metastatic spread. Simultaneous synthesis of these three different proteins is also possible via the plasminogen-urokinase system. VEGF is reported to increase vascular permeability, which in turn causes pleural effusions. The results presented here may be the basis for possible future palliative therapeutical strategies in malignant pleural effusions.