肝纤维化时肝脏OPN和PAI-1的表达变化

目的:研究骨桥蛋白(OPN)及纤溶酶原激活物抑制物(PAI-1)的表达特征及其在肝纤维化时的变化。方法:采用二甲基亚硝胺制作大鼠肝纤维化模型,大鼠肝脏常规HE和天狼猩红染色,采用SABC法做免疫组织化学染色及Western blotting检测OPN和PAI-1蛋白表达,抽提肝组织总RNA,RT-PCR检测OPN mRNA表达。结果:正常大鼠肝组织OPN和PAI-1表达极弱,肝纤维化大鼠肝脏中OPN表达增强,阳性信号散在或弥漫性分布,主要见于小叶内中央静脉周围、纤维间隔内以及周围巨噬细胞胞浆、枯否氏细胞、汇管区的部分肝细胞、肝窦壁内皮细胞。PAI-1在肝纤维化大鼠肝组织汇管区、肝细胞变性坏死处,肝窦周Disse间隙及毗邻以上部位的肝细胞,组织纤维间隔处及其外周细胞亦见阳性染色。Western blotting检测正常大鼠肝脏OPN的蛋白表达极低,肝纤维化组OPN的蛋白表达较正常组显著增强(P0.01)。与正常组比,肝纤维化组PAI-1表达也显著增强。RT-PCR检测结果显示,正常大鼠肝脏OPN mRNA表达极低,肝纤维化大鼠肝脏OPN mRNA的表达明显增强(P0.05)。研究结果证明,肝纤维化时大鼠肝组织OPN及PAI-1的表达水平显著增高。结论:肝纤维化时大鼠肝组织OPN及PAI-1的表达水平显著增高,OPN可能会促进PAI-1的高表达,从而抑制ECM降解、加速肝纤维化进程。     

辣椒素抑制大鼠肝纤维化的实验研究

 目的：探讨辣椒素（capsaicin）对大鼠肝星状细胞（hepatic stellate cells, HSCs）活性的影响及其对实验性肝纤维化的治疗作用。方法：DCFH-DA法检测辣椒素对HSCs中活性氧的影响;CCK-8法检测辣椒素对HSCs增殖的影响;Western blotting检测HSCs α-平滑肌肌动蛋白的表达;RT-PCR检测辣椒素对HSCs纤维化相关基因表达的影响;流式细胞术检测辣椒素对HSCs凋亡的影响;通过腹腔注射四氯化碳建立鼠肝纤维化模型,经腹腔输注辣椒素,检测肝组织病理切片,观察肝纤维化指标的变化。结果：与对照组比较,辣椒素抑制了HSCs中活性氧的产生,明显抑制了HSCs的活化与增殖(P<0.05),促进了HSCs的凋亡(P<0.05),降低了金属蛋白酶组织抑制物1及转化生长因子β 1的表达(P<0.05),降低了肝羟脯氨酸含量及血清Ⅲ型胶原和透明质酸水平(P<005)。结论：辣椒素抑制HSCs增殖、活化并诱导其凋亡。辣椒素对实验性肝纤维化具有一定的抑制作用。     

辛二酰苯胺异羟肟酸诱导大鼠原代肝星状细胞凋亡

目的:通过研究辛二酰苯胺异羟肟酸(SAHA)对大鼠原代肝星状细胞(HSCs)凋亡及相关蛋白表达的影响,探讨SAHA诱导HSCs凋亡的作用机制。方法:采用Opti Prep梯度离心法分离大鼠原代HSCs;通过实时细胞分析技术检测SAHA对HSCs增殖的影响;倒置显微镜观察不同浓度SAHA处理HSCs后的形态变化;荧光显微镜及流式细胞术Annexin V-FITC/PI法检测细胞凋亡率;Western blotting法检测α-平滑肌肌动蛋白(α-SMA)、Ⅰ型胶原、金属蛋白酶组织抑制物1(TIMP1)、葡萄糖调节蛋白78(GRP78)和组蛋白去乙酰化酶6(HDAC6)的蛋白表达;免疫共沉淀法检测GRP78蛋白与HDAC6蛋白是否形成复合物。结果:成功分离的HSCs连续培养14 d,HSCs逐渐由静止状态变为激活状态。SAHA可显著抑制HSCs增殖,且呈剂量时间依赖性(P0.05);SAHA对HSCs的促凋亡作用具有时间依赖性(P0.05)。SAHA处理HSCs后,α-SMA、Ⅰ型胶原、HDAC6和TIMP1的蛋白表达水平明显降低(P0.05),GRP78的蛋白表达水平明显升高(P0.05)。与激活型的HSCs相比,SAHA处理后的HSCs中免疫共沉淀下的蛋白复合物中GRP78与总的乙酰化赖氨酸蛋白显著增多,而HDAC6蛋白显著降低,同时证明GRP78与HDAC6形成复合物。结论:SAHA抗肝纤维化的机制可能是,SAHA下调HDAC6蛋白表达水平,上调乙酰化GRP78蛋白表达水平,诱导HSCs内质网应激,促进肝星状细胞凋亡,从而起到抗肝纤维化的作用。     

肝再生过程中肝星状细胞及基质金属蛋白酶的动态变化

目的研究大鼠肝大部切除(PH)后再生过程中肝星状细胞(HSCs)的动态变化及肝MMP-2、MMP-9的活性变化,探讨肝星状细胞在肝再生中的作用。方法按Higgins等方法制备肝大部切除动物模型,于术后恢复不同时程取材,免疫组织化学法检测肝HSCs的动态变化,明胶酶谱电泳法检测肝中MMP-2、MMP-9的变化。结果(1)正常肝小叶内HSCs呈网架状分布,PH后Desmin阳性HSCs的数量递减;胶质纤维酸性蛋白(GFAP)阳性HSCs的数量也呈递减趋势。(2)PH后再生过程中,肝脏MMP-2、MMP-9的表达逐渐增多。结论肝再生过程中HSCs的增殖反应较慢且维持的时间短,这不同于肝纤维化等肝病过程中HSCs维持较长时间的激活状态。肝再生过程中基质金属蛋白酶-2,-9的表达发生显著改变,提示基质金属蛋白酶-2,-9参与了肝再生过程。     

脂肪特异性蛋白27对大鼠肝星状细胞活化的影响

 目的：探讨脂肪特异性蛋白27（Fsp27）对肝星状细胞（HSCs）增殖和活化的影响及其对纤维化相关蛋白的调节作用。方法：从SD大鼠肝脏提取HSCs并培养,采用实时荧光定量PCR、免疫荧光染色和Western blotting检测原代HSCs和活化HSCs中Fsp27 mRNA和蛋白的表达。构建携带Fsp27基因的慢病毒,转染活化的HSCs并继续培养72 h,通过CCK-8比色法检测Fsp27对HSCs增殖的影响;Western blotting检测HSCs中α-平滑肌肌动蛋白（α-SMA）的表达,了解HSCs的活化状态;实时荧光定量PCR检测Fsp27对HSCs中纤维化相关蛋白［包括基质金属蛋白酶2（MMP-2）、金属蛋白酶组织抑制物1（TIMP-1）和转化生长因子β1（TGF-β1）］ mRNA表达的影响。结果：成功分离大鼠原代HSCs。Fsp27在原代HSCs和活化HSCs中的表达差异显著（P<0.01）;活化HSCs成功转染携带Fsp27基因的慢病毒后继续培养72 h,与对照组比较,HSCs的活化与增殖被明显抑制（P<0.05）;Fsp27促进MMP-2 mRNA的表达（P<0.05）,降低TIMP-1和TGF-β1 mRNA的表达（P<0.05）。结论：Fsp27可抑制HSCs的增殖和活化,并调节纤维化相关蛋白的表达。Fsp27的作用可能与其维持HSCs静息状态细胞表型有关。     

大鼠肝纤维化与microRNA-181a调控肝星状细胞自噬的关系

目的:观察四氯化碳(CCl4)诱导肝纤维化(HF)大鼠肝脏结构的改变、肝组织中转化生长因子β1(TGF-β1)、微小RNA-181a(microRNA-181a)、自噬标志性蛋白LC3-II/-I和beclin-1水平及胶原沉积的变化,以及mi?croRNA-181a对TGF-β1诱导大鼠肝星状细胞(HSCs)自噬的作...     

神经生长因子对肝星状细胞胶原分泌及形态学的影响

目的: 观察神经生长因子(NGF)对大鼠肝星状细胞(HSCs)胶原分泌功能和形态学的影响,探讨NGF抗肝纤维化的作用机制。方法: 大鼠肝星状细胞株(HSCs-T6)经不同浓度NGF作用24 h后,ELISA法检测上清液中Ⅰ、Ⅲ型胶原的含量;通过倒置显微镜、吖啶橙染色及透射电镜观察形态学变化。结果: NGF作用HSCs 24 h后培养上清中Ⅰ、Ⅲ型胶原的含量与对照组相比明显减少(P<0.05),但无剂量依赖性。倒置显微镜下可见细胞数目变少,细胞变小,形态向椭圆形或圆形改变;吖啶橙染色及透射电镜可以见到细胞凋亡的形态学变化。结论: NGF可抑制HSCs合成Ⅰ、Ⅲ型胶原,诱导HSCs凋亡,抑制HSCs胶原分泌,可能是NGF抗肝纤维化的作用机制。     

大鼠原代肝星状细胞活化后组蛋白修饰水平的观察

目的:观察体外培养大鼠肝星状细胞(HSCs)活化过程中组蛋白修饰的改变以及与HSCs活化指标α-平滑肌肌动蛋白(α-SMA)的关系,探讨组蛋白修饰在HSCs活化过程中可能的作用。方法:体外分离、鉴定、培养大鼠HSCs,光镜观察HSCs活化过程中的形态变化,细胞免疫荧光染色和Western blotting检测desmin和α-SMA的表达,比较静止型HSCs和激活型HSCs中H4K12乙酰化、H3K9乙酰化、H3K4二甲基化和H3K9二甲基化的变化。结果:(1)细胞形态学观察结果表明HSCs在培养过程中形态由静息状态向高度分化的肌成纤维细胞转化。细胞免疫荧光染色及Western blotting检测结果显示,分离培养24 h的HSCs有desmin表达,但几乎不表达α-SMA;随着培养时间延长,HSCs内α-SMA和desmin表达逐步增加,至15 d时达到最大。(2)根据HSCs细胞形态变化及HSCs活化标志蛋白检测结果,确定培养24 h的HSCs为静止型HSCs,培养15 d的HSCs为激活型HSCs,分别检测其组蛋白修饰变化。结果显示,与静止型HSCs比较,激活型HSCs中H4K12乙酰化、H3K9乙酰化和H3K9二甲基化修饰水平明显降低(P0.01),而H3K4二甲基化修饰水平明显增加(P0.01),且H3K4二甲基化修饰水平变化与α-SMA表达变化一致。结论:在体外培养HSCs活化过程中,组蛋白修饰发生明显异常,提示组蛋白修饰改变有可能参与了HSCs活化以及肝纤维化的发生。     

神经生长因子低亲合力受体在肝纤维化患者和大鼠肝星状细胞的表达

目的探讨神经生长因子低亲合力受体（P75）在肝纤维化患者和大鼠肝星状细胞（HSCs）的分布及作用机制。方法对四氯化碳（CCL）法制备的肝纤维化大鼠肝组织及肝穿刺获取的肝纤维化患者肝组织,常规石蜡包埋;大鼠离体培养的活化HSCs离心涂片,行免疫组织化学染色,确定P75的表达分布。结果P75在大鼠离体培养的活化HSCs膜,免疫组织化学染色呈阳性,在肝纤维化患者HSCs膜和肝细胞膜,免疫组织化学染色呈阳性,在肝纤维化大鼠HSCs膜和肝细胞膜,免疫组织化学染色呈阳性,在健康人和正常对照大鼠HSCs膜,免疫组织化学染色呈阴性,表明人和大鼠活化的HSCs膜表达P75。结论P75为肝纤维化的治疗提供了新的靶点。     

脂肪酸对人血管内皮细胞纤溶酶原激活物抑制剂-1表达的影响

为探讨不同种类脂肪酸对血管内皮细胞(ECs)纤溶酶原激活物抑制剂-1(PAI-1)表达的直接影响及影响水平，以不同浓度的亚麻酸、亚油酸、油酸、硬脂酸诱导培养ECs，逆转录聚合酶链式反应(RT-PCR)和酶联免疫吸附法。（ELISA)检测PAI-1的mRNA和蛋白表达，随后以上述脂肪酸诱导转染了由PAI-1启动子控制表达的报告基因的ECs，ELISA检测PAI-1启动子转录活性，结果ECs中亚麻酸、亚油酸和油酸均浓度依赖地诱导PAI-1 mRNA和蛋白表达，硬脂酸无影响，而它们对PAI-1启动子转录活性的影响与上述作用一致，提示不饱和脂肪酸通过提高PAI-1转录活性诱导其在ECs的表达。     

苦瓜对实验性大鼠肝纤维化的干预作用及可能机制

目的: 探讨苦瓜(BM)对四氯化碳(CCl₄)诱导大鼠肝纤维化的干预作用及相关机制。方法: 随机将32只雄性健康Wistar大鼠分为4组:对照组(C组);模型组(CCl₄,M组);BM低剂量组(BM 100g/kg饲料+CCl₄,BM-L组)、BM高剂量组(BM 200g/kg饲料+CCl₄,BM-H组)。饲养中除C组外的各组大鼠均皮下注射50%CCl₄-橄榄油溶液2 mL/kg,2次/周,共8周,诱导肝纤维化动物模型。8周后处死大鼠,留取大鼠肝脏和血清。计算肝体指数;测定血清丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性;测定肝匀浆总蛋白(TP)和白蛋白(Alb)含量、谷胱甘肽过氧化物酶(GSH-Px)活性、羟脯氨酸(HYP)含量和单胺氧化酶(MAO)活性;胶原纤维染色观察大鼠肝组织变性与胶原沉积病理改变。结果: 与M组比较,摄入BM后的各剂量组大鼠肝体指数显著降低(P<0.01);血清MDA含量及肝匀浆HYP含量和MAO活性均明显降低(P<0.01),而血清SOD活性、肝组织TP和Alb含量、GSH-Px活性明显增强(P<0.01)。与正常大鼠相比,模型大鼠肝脏有明显胶原沉积与肝纤维化,伴有不同程度的肝细胞炎性损伤坏死;BM组明显减轻模型大鼠肝组织损伤坏死与胶原沉积等病理变化,以高剂量组更明显。结论: BM具有抗CCl₄诱导大鼠肝纤维化作用,其机制可能与其抗脂质过氧化、降低肝HYP含量及MAO活性的作用有关。     

Expression of urokinase-type plasminogen activator, urokinase-type plasminogen activator receptor, and plasminogen activator inhibitor-1 and -2 in hepatocellular carcinoma

It has become more and more clear in recent decades that the plasminogen activation system, which includes urokinase-type plasminogen activator (uPA), urokinase-type plasminogen activator receptor (uPAR), plasminogen activator inhibitor (PAI)-1 and PAI-2, plays a very important role in the aggressiveness of cancer. Using immunohistochemistry and enzyme-linked immunosorbent assay (ELISA), the expression of these four components of the uPA system was analyzed in 19 cases of hepatocellular carcinoma (HCC) and 18 cases of the adjacent non-cancer tissues which all had chronic active hepatitis with liver fibrosis or liver cirrhosis. Four cases of normal liver tissues, as controls for immunohistochemical stains, were obtained from the hepatectomized liver of patients with metastatic cancer in the liver. The positive rates of uPA, uPAR, PAI-1 and PAI-2 for immunohistochemical stains in cancer tissues were 78.9, 68.4, 57.9 and 31.6%, respectively. Positive signals were mainly distributed in the cytoplasm of the cancer and in stromal cells. Moreover, the strong stains were chiefly located in the invasive front of the cancer cells. No specific stain was detected in four cases of normal liver tissues. In ELISA, there were significant differences between cancer and non-cancer tissues in concentration of uPA, uPAR and PAI-1 (P < 0.0003, 0.0024 and 0.01, respectively), but there was no significant difference in that of PAI-2 (P = 0.37). These results suggest that uPA, uPAR and PAI-1 are related to invasion of HCC.     

Role of the Urokinase-Fibrinolytic System in Epithelial–Mesenchymal Transition during Lung Injury

Alveolar type II epithelial (ATII) cell injury precedes development of pulmonary fibrosis. Mice lacking urokinase-type plasminogen activator (uPA) are highly susceptible, whereas those deficient in plasminogen activator inhibitor (PAI-1) are resistant to lung injury and pulmonary fibrosis. Epithelial–mesenchymal transition (EMT) has been considered, at least in part, as a source of myofibroblast formation during fibrogenesis. However, the contribution of altered expression of major components of the uPA system on ATII cell EMT during lung injury is not well understood. To investigate whether changes in uPA and PAI-1 by ATII cells contribute to EMT, ATII cells from patients with idiopathic pulmonary fibrosis and chronic obstructive pulmonary disease, and mice with bleomycin-, transforming growth factor β–, or passive cigarette smoke–induced lung injury were analyzed for uPA, PAI-1, and EMT markers. We found reduced expression of E-cadherin and zona occludens-1, whereas collagen-I and α-smooth muscle actin were increased in ATII cells isolated from injured lungs. These changes were associated with a parallel increase in PAI-1 and reduced uPA expression. Further, inhibition of Src kinase activity using caveolin-1 scaffolding domain peptide suppressed bleomycin-, transforming growth factor β–, or passive cigarette smoke–induced EMT and restored uPA expression while suppressing PAI-1. These studies show that induction of PAI-1 and inhibition of uPA during fibrosing lung injury lead to EMT in ATII cells.Idiopathic pulmonary fibrosis (IPF) and other interstitial lung diseases are characterized by destruction of lung architecture due to excessive deposition of extracellular matrix proteins by activated fibroblasts or myofibroblasts, leading to progressive dyspnea and loss of lung function.^1–3 The origins of myofibroblasts participating in the pathological remodeling of IPF lungs are not clear. Histopathological evaluation demonstrates that myofibroblasts accumulate in fibroblastic foci. Emerging evidence suggests that polarized type II alveolar epithelial (ATII) cells undergo epithelial–mesenchymal transitions (EMT) after lung injury. The ATII cells assume phenotypic changes such as increased migration, invasion, resistance to apoptosis, and production of elevated levels of extracellular matrix proteins^4,5 and therefore serve as a source of myofibroblasts. Understanding the possible mechanisms contributing to EMT in ATII cells may help identify new targets to treat or at least limit fibrogenesis after lung injury.A number of molecular processes are involved in the initiation of EMT in ATII cells.⁵ Components of the fibrinolytic system such as urokinase-type plasminogen activator (uPA), uPA plasma membrane receptor (uPAR), and its major inhibitor, plasminogen activator inhibitor (PAI-1) are all elaborated by ATII cells. These proteins independently influence a broad range of biological processes germane to lung injury and its repair.⁶ However, their role in fibrogenesis via EMT is unclear. Recent publications using bleomycin (BLM)⁷ and a passive cigarette smoke (PCS)⁸ or adenovirus expressing constitutively active transforming growth factor β (Ad-TGF-β)^1,9 exposure model of lung injury indicate that a coordinate increase in PAI-1 and a decrement in uPA by ATII cells promote lung injury and subsequent pulmonary fibrosis (PF). We also found that caveolin-1 scaffolding domain peptide (CSP) acts as a competitor to caveolin-1, restores expression of uPA and uPAR, and inhibits PAI-1 in ATII cells after lung injury. These changes prevent development of PF after lung injury.⁷ Recent literature suggests that up to 30% to 50% of myofibroblasts may be derived via EMT during fibrogenesis.^10–12 However, an in vivo genetic lineage tracing study reported by Rock et al¹³ contradicts these findings. Our objective in the current study is to elucidate the role of altered expression of uPA, uPAR, and PAI-1 after lung injury in EMT, and further evaluate whether reinstatement of baseline expression of uPA, uPAR, and PAI-1 by CSP intervention after lung injury reduces EMT in ATII cells.     

IGFBPrP1与硫代乙酰胺对小鼠肝组织的影响及其机制

目的:通过对胰岛素样生长因子结合蛋白相关蛋白1(IGFBPrP1)与硫代乙酰胺(TAA)对小鼠肝组织影响的研究,明确IGFBPrP1在肝纤维化中的作用及其机制。方法:清洁级C57BL/6野生型小鼠32只,随机分为4组:正常对照组、重组小鼠IGFBPrP1(rmIGFBPrP1)4周组、TAA2周组及TAA4周组,每组8只。取肝组织行HE、苦味酸-天狼星红及免疫组织化学染色和Westernblotting检测。结果:rmIGFBPrP14周组肝细胞广泛脂肪变性,TAA2周组出现纤维组织增生,TAA4周组病理改变较TAA2周组严重。与正常对照组相比,rmIGFBPrP14周组、TAA2周组和TAA4周组IGFBPrP1、转化生长因子β1(TGF-β1)、Smad3、p-Smad2/3、Ⅲ型胶原(ColⅢ)、I型胶原(ColⅠ)、纤维连接蛋白(FN)的表达增高(P0.05)。rmIGFBPrP14周组IGFBPrP1、ColⅠ和FN的表达与TAA2周组无显著差异。结论:IGFBPrP1在TAA诱导的肝纤维化形成过程中发挥重要作用,并可作为独立致病因子引起小鼠肝组织中细胞外基质生成增多,且该作用是通过TGF-β1/Smad3信号通路来实现的。     

抗IGFBPrP1抗体对小鼠肝纤维化的预防作用及其机制的研究

目的: 明确抗胰岛素样生长因子结合蛋白相关蛋白1(IGFBPrP1)抗体能否预防硫代乙酰胺(TAA)诱导的小鼠肝纤维化的形成,同时探讨其机制。方法: 将24只雄性C57BL/6野生型小鼠随机分为正常对照组、TAA 4周组和TAA+抗IGFBPrP1抗体4周组,每组8只,观察肝组织形态学改变,免疫组织化学染色和Western blotting检测肝组织中α-平滑肌肌动蛋白(α-SMA)、转化生长因子β₁(TGF-β₁)、Smad3、磷酸化Smad2/3(p-Smad2/3)、纤维连接蛋白(FN)、Ⅰ、Ⅲ型胶原(collagen Ⅰ、Ⅲ)及IGFBPrP1的表达。结果: TAA 4周组肝损伤严重,α-SMA、TGF-β₁、Smad3、p-Smad2/3、FN、collagen Ⅰ、Ⅲ及IGFBPrP1的表达明显高于正常对照组(P＜0.01),TAA+抗IGFBPrP1抗体4周组肝损伤减轻,上述各指标表达均低于TAA 4周组(P＜0.01)。IGFBPrP1与TGF-β₁、Smad3、p-Smad2/3 、FN及collagen Ⅰ的表达呈正相关(P＜0.01)。结论: 抗IGFBPrP1抗体可预防TAA诱导的小鼠肝纤维化的形成,其机制为抑制肝星状细胞的活化和减少细胞核内p-Smad2/3的表达、抑制TGF-β₁/Smad3信号通路,进而导致细胞外基质在肝组织中沉积减少。     

Effect of cholinergic denervation on hepatic fibrosis induced by carbon tetrachloride in rats

Various factors involved in the development of liver fibrosis, including hepatic stellate cells (HSCs), cholinergic nervous activity and fibrogenetic cytokines. The present study aims to investigate the role of cholinergic regulation in the promoting of liver fibrogenesis relating to bone morphogenetic protein-6 (BMP-6) and/or transforming growth factor-beta1 (TGFbeta1). We treated carbon tetrachloride (CCl(4)) into rats for eight weeks to induce liver fibrosis and arranged these rats for cholinergic denervation, hepatic branch vagotomy or atropine administration. Acetylcholinesterase (AChE) staining showed the distribution of cholinergic nerve around fibrosis scaring septa. The immunohistochemical staining for alpha smooth muscle actin (alphaSMA) indicated the less HSCs in CCl(4) treated rat liver with cholinergic denervation as compared to the sham-operated CCl(4) treated rats. It seems that cholinergic nerve not only innervates around the fibrosis area but also promotes HSCs. We also detected TGFbeta1 and BMP-6 expressions using RT-PCR and immunohistochemistry. The obtained results show that cholinergic denerveration decreases BMP-6 and TGF-beta1 expressions in CCl(4) induced liver fibrosis of rats. In conclusion, cholinergic nerve may influence HSCs in addition to the lowering of BMP-6 and TGF-beta1 gene expressions to modify liver fibrosis.     

Promigratory Effect of Plasminogen Activator Inhibitor-1 on Invasive Breast Cancer Cell Populations

The urokinase-type plasminogen activator (uPA) system is a dynamic complex in which the membrane receptor uPAR binds uPA that binds the plasminogen activator inhibitor (PAI)-1 localized in the extracellular matrix, resulting in endocytosis of the whole complex by the low-density lipoprotein receptor-related protein (LRP). High expression of PAI-1 is paradoxically associated with marked tumor spreading and poor prognosis. We previously reported a nonproteolytic role of the [uPAR:uPA:PAI-1:LRP] complex operative in cell migration. Here we explored whether matrix PAI-1 could be used as a migration support by human breast cancer cells. We showed that the uPA system and LRP are localized at filopodia of invasive cells, and that formation/internalization of the [uPAR:uPA:PAI-1:LRP] complex is required for attachment and migration of cancer cells on plastic and on a PAI-1 coat. PAI-1 increased both filopodia formation and migration of cancer cells suggesting a chemokine-like activity. Migration velocity, expression of the uPA system, use of the [uPAR:uPA:PAI-1:LRP] complex to migrate, and promigratory effects of PAI-1 paralleled cancer cell invasiveness. Phenotyping and functional analysis of invasive cancer cell subclones indicated that different cell subpopulations may use different strategies to migrate depending on both the environment and their expression of the uPA system, some of them taking advantage of abundant available PAI-1.