尿激酶纤溶酶原激活物系统与肿瘤血管形成

恶性肿瘤合成分泌大量胞外蛋白水解酶，降解细胞外基质及基底膜，是恶性肿瘤侵袭转移及新生血管形成的重要基础。尿激酶纤溶酶原激活物(uPA)系统作为主要的蛋白水解酶在其中发挥重要作用。就uPA系统的结构、功能及其在肿瘤新生血管形成的作用作简单介绍。     

尿激酶纤溶酶原激活物系统与肿瘤侵袭转移

恶性肿瘤合成分泌大量胞外蛋白水解酶,降解细胞外基质及基底膜,是恶性肿瘤侵袭转移的重要基础.尿激酶纤溶酶原激活物(uPA)系统作为主要的蛋白水解酶在其中发挥重要作用.本简述uPA系统的结构、功能及其在侵袭、转移中的作用.     

uPA系统对乳腺癌的影响及在预后与治疗方面的研究进展

恶性肿瘤的侵袭及转移需要细胞外基质的降解,涉及到很多蛋白水解酶类,其中包括尿激酶型纤溶酶原激活物（uPA）系统。uPA系统不仅促进肿瘤的侵袭及转移,还参与癌细胞增殖与肿瘤血管形成。本文对uPA系统在乳腺癌中的作用,临床预后价值,以及目前靶向治疗的最新进展作一综述。     

uPA系统对乳腺癌的影响及在预后与治疗方面的研究进展

恶性肿瘤的侵袭及转移需要细胞外基质的降解,涉及到很多蛋白水解酶类,其中包括尿激酶型纤溶酶原激活物(uPA)系统.uPA系统不仅促进肿瘤的侵袭及转移,还参与癌细胞增殖与肿瘤血管形成.本文对uPA系统在乳腺癌中的作用,临床预后价值,以及目前靶向治疗的最新进展作一综述.     

尿激酶型纤溶酶原激活物系列与肿瘤转移

尿激酶型纤溶酶原激活物(uPA)属丝氨酸蛋白水解酶,uPA与其受体(uPAR)、抑制剂(uPAI)所形成的作用系统可激活纤溶酶原参与细胞外基质的降解,介导肿瘤的侵袭和转移.现对uPA作用系统中的主要组分及其在肿瘤侵袭转移中作用作一简要介绍.     

尿激酶型纤溶酶原激活物系列与肿瘤转移

尿激酶型纤溶酶原激活物(uPA)属丝氨酸蛋白水解酶，uPA与其受体(uPAR)、抑制剂(uPAI)所形成的作用系统可激活纤溶酶原参与细胞外基质的降解，介导肿瘤的侵袭和转移。现对uPA作用系统中的主要组分及其在肿瘤侵袭转移中作用作一简要介绍。     

尿激酶型纤溶酶原激活物作用系统与肿瘤转移

恶性肿瘤的侵袭转移是引起肿瘤患者治疗失败和死亡的主要原因之一.肿瘤的侵袭与转移机制复杂,是一个多环节、多步骤的过程,其中肿瘤合成分泌大量的胞外蛋白水解酶,穿透细胞外基质尤为重要,该环节可分为粘附、水解、游走三个步骤,而基质蛋白酶水解作为其中的关键倍受人们的关注.尿激酶型纤溶酶原激活物（urokinase-type plasminogen activator,uPA）系统在肿瘤侵袭转移中的作用成为当今研究的热点之一.uPA系列包括uPA、uPA前体（prourokinase-type plasminogen activator,pro-uPA）、uPA受体（urokinase-type plasmino-gen activator receptor,uPAR）及uPA抑制因子（uroki-nase-type plasminogen activator inhibitor,uPAI）等.它们作为主要的蛋白降解酶与恶性肿瘤细胞的迁移、侵袭、转移及预后密切相关.     

胃癌侵袭和转移分子机制研究进展

胃癌是我国常见的恶性肿瘤之一 ,占消化道恶性肿瘤第一位 ,癌细胞侵袭和转移是影响其疗效的主要原因。胃癌侵袭和转移的过程非常复杂 ,从分子水平可将其归纳为：粘附分子介导癌细胞与正常细胞、细胞外基质（ＥＣＭ）进行粘附 ;癌细胞释放多种蛋白水解酶降解所粘附的组织 ;水解酶使胃癌细胞粘附部位形成空隙 ,从而使胃癌细胞向纵深方向或远处运动 ;着床的癌细胞在多种促血管生成因子的作用下形成新生血管 ;癌细胞通过自身机制逃避宿主免疫监视系统的杀伤作用得以生存增殖。明确胃癌侵袭和转移具体的分子机制 ,采取有效的阻断转移 ,对估计预后…     

中老年人肺癌抗血管和抗淋巴管生成治疗的可行性探讨

肿瘤的侵袭和转移是恶性肿瘤死亡的主要原因.基质金属蛋白酶9(MMP-9)是降解基底膜和细胞外基质成分的蛋白水解酶,可促进癌细胞对周围组织的浸润,在肿瘤血管生成及肿瘤侵袭和转移过程中起重要调节作用.乙酰肝素酶(HPSE)在多种人类恶性肿瘤中高度表达,具有促进肿瘤细胞侵袭和转移的重要作用,并且与肿瘤新生血管的形成具有密切关系.血管内皮生长因子C(VEGF-C)是迄今发现的唯一特异性促淋巴管生长因子.肺癌是人类最常见的恶性肿瘤,目前所有的各种治疗肺癌的方法效果均不能令人满意.本研究采用免疫组织化学染色方法检测了65例肺癌组织、癌旁组织和正常肺组织中MMP-9,HPSE和VEGF-C蛋白的表达,以探讨人肺癌抗血管和淋巴管生成治疗的可行性.     

uPA／uPAR系统与恶性肿瘤侵袭转移的关系

肿瘤细胞的侵袭和转移是一个多步骤、多环节过程,涉及瘤细胞穿越细胞外基质屏障、血管壁的基底膜及穿出血管壁进入宿主微循环的过程。大量事实证明,癌细胞侵袭转移能力与其诱导产生蛋白溶解酶降解细胞外基质、基底膜的能力密切相关。细胞外基质可分成基底膜和间质组织,它们都是由基底物（糖蛋白、蛋白多糖）、弹性蛋白和胶原构成的致密网络,在肿瘤的浸润转移中它们起到屏障作用。肿瘤组织中一些蛋白水解酶的高表达,尤其是uPA／uPAR系统被认为在肿瘤的侵袭转移过程中具有重要作用。     

LIM kinase 1 increases tumor metastasis of human breast cancer cells via regulation of the urokinase-type plasminogen activator system

Mammalian LIM kinase 1 (LIMK1) phosphorylates and inactivates the actin-binding and -depolymerizing factor cofilin and induces actin cytoskeletal changes. LIMK1 is reported to play an important role in cell motility, but the mechanism of induction of cell motility and the role of LIMK1 in tumor growth, angiogenesis and invasion are poorly understood. Here we show that expression of LIMK1 in MDA-MB-435 human breast cancer cells enhanced cell proliferation and cell invasiveness and promoted in vitro angiogenesis. Since tumor metastasis requires degradation of the extracellular matrix by the serine protease urokinase type plasminogen activator (uPA), we examined the role of LIMK1 in the regulation of uPA/uPAR system. LIMK1 overexpression in breast cancer cells upregulated the uPA system, increased uPA promoter activity, induced uPA and uPAR mRNA and protein expression and induced uPA secretion. In contrast, cells transfected with the catalytically inactive LIMK mutant D460N-LIMK1 did not exhibit these phenotypic changes. Blocking antibodies against uPA and uPAR suppressed LIMK1-induced cell invasiveness. In addition, LIMK1 overexpression increased tumor growth in female athymic nude mice, promoted tumor angiogenesis and induced metastasis to livers and lungs, possibly by increasing uPA expression in the tumors. Finally, LIMK1 and uPAR were coordinately overexpressed in human breast tumors. These results suggested an important role for LIMK1 signaling in breast cancer tumor growth, angiogenesis and invasion and a regulatory connection between LIMK1 and the uPA system.     

Recombinant PAI-1 inhibits angiogenesis and reduces size of LNCaP prostate cancer xenografts in SCID mice

To understand the fundamental determinants of urokinase plasminogen activator (uPA) driven angiogenesis in cancer we studied how inhibition of uPA activity could reduce neovascularization and consequently reduce tumor size in experimental animals. Proteolytic enzymes are required to mediate tumor cell invasion to adjacent tissues and initiate the metastatic process. Many different human cancers commonly overexpress the urokinase plasminogen activator system, one of the proteolytic enzyme systems. Reduction of urokinase activity in cancer cells is evidently associated with diminished invasion and metastasis. However, it has been shown recently that inhibitors of uPA could reduce tumor size also. The mechanism of action leading to decline in tumor growth rate is not clear. Proteolysis is responsible for degradation of proteins, for invasion or metastasis, but not for the proliferate properties of the cancer cells. It is difficult to envision that diminishing the size of tumor is due to simply blocking of uPA activity of cancer cells. Instead, inhibitors of uPA may be interacting with the elements of the extracellular matrix, such the neovascular bed surrounding tumors that has been reported to contain high amounts of uPA and its receptor. Overall these data strongly suggest that inhibitors of urokinase limit cancer growth by inhibiting angiogenesis. However, it is possible also that uPA inhibitors could act on cancer cells directly or prevent angiogenesis by alternative mechanisms that are not related to uPA inhibition. Therefore, we examined if plasminogen activator inhibitor (PAI-1) could limit angiogenesis. If it does, it will provide definitive evidence of uPA/PAI-1 involvement in reduction of cancer growth. Indeed, our study demonstrates that exogenously applied 14-1b PAI-1 is a powerful inhibitor of angiogenesis in three different in vitro models and is a powerful anti-cancer agent in a SCID mice model inoculated with human LNCaP prostate cancer cells.     

Urokinase-type plasminogen activator expression correlates with tumor angiogenesis and poor outcome in gastric cancer

Urokinase plasminogen activating system (PA system) and vascular endothelial growth factor (VEGF) were recently suggested to contribute synergistically to tumor progression. To evaluate the roles of the PA system and VEGF in gastric cancer, the effects of the PA system and VEGF on tumor angiogenesis and the survival of patients with gastric cancer were investigated. Cancer tissues from 101 gastric cancer patients were assayed immunohistochemically for expression of urokinase-type plasminogen activator (uPA), uPA receptor (uPAR), PA inhibitor-1 (PAI-1) and VEGF protein. The positive rates of uPA, uPAR, PAI-1, VEGF expression were 22.8%, 32.7%, 36.6% and 26.7%, respectively. Positive staining was observed in tumor cells (uPA, uPAR, VEGF), or in both tumor cells and stromal cells (PAI-1). The expressions of uPA, uPAR, PAI-1 and VEGF were significantly correlated with the clinicopathological factors: uPA, depth of tumor invasion, differentiation, lymphatic and vascular invasion; uPAR, tumor size, depth, lymph node involvement, differentiation, vascular invasion; PAI-1, tumor size, depth, lymph node involvement, differentiation, vascular invasion; VEGF, differentiation, vascular invasion. The microvessel density (MVD) assessed immunohistochemically was significantly higher in the patients with expression of uPA, uPAR or VEGF, and stepwise analysis identified uPA as an independent correlated factor with MVD. Furthermore, multivariate analysis demonstrated that depth of tumor invasion, lymph node involvement and uPA expression were independent prognostic factors. uPA is a key factor in the PA system, being associated with a poor outcome of gastric cancer, and contributing not only to invasive activity, but also to angiogenesis. (Cancer Sci 2003; 94: 43–49)     

Evolving role of uPA/uPAR system in human cancers

Recent advancements in cancer research have led to some major breakthroughs; however, the impact on overall cancer-related death rate remains unacceptable, suggesting that further insight into tumor markers and development of targeted therapies is urgently needed. The urokinase plasminogen activator (uPA) system represents a family of serine proteases that are involved in the degradation of basement membrane and the extracellular matrix, leading to tumor cell invasion and metastasis. In this review, we have provided an overview of emerging data, from basic research as well as clinical studies, highlighting the evolving role of uPA/uPAR system in tumor progression. It is currently believed that the expression and activation of uPA plays an important role in tumorigenicity, and high endogenous levels of uPA and uPAR are associated with advanced metastatic cancers. The endogenous inhibitors of this system, PAI-1 and PAI-2, regulate uPA-uPAR activity by either direct inhibition or affecting cell surface expression and internalization. PAI-1's role in cancers is rather unusual; on one hand, it inhibits uPA-uPAR leading to inhibition of invasion and metastasis and on the other it has been reported to facilitate tumor growth and angiogenesis. Individual components of uPA/uPAR system are reported to be differentially expressed in cancer tissues compared to normal tissues and, thus, have the potential to be developed as prognostic and/or therapeutic targets. Therefore, this system represents a highly attractive target that warrants further in-depth studies. Such studies are likely to contribute towards the development of molecularly-driven targeted therapies in the near future.     

Regulation of the urokinase-type plasminogen activator system by the von Hippel-Lindau tumor suppressor gene.

The urokinase-type plasminogen activator (uPA) system plays an important role in tumor cell invasion, metastases, and angiogenesis. uPA, uPA receptor, and plasminogen activator inhibitor 1 (PAI-1) are prognostic factors in different solid tumors, e.g., renal cell carcinomas (RCCs). von Hippel-Lindau (VHL) disease is an inherited cancer syndrome that is characterized by extensively vascularized tumors, including hemangioblastomas and RCCs. In 75% of sporadic RCCs, the VHL gene is also inactivated. It has been recognized in sporadic RCC that PAI-1 mRNA levels are up-regulated and uPA mRNA levels are down-regulated. We determined the role of the VHL tumor suppressor gene in the regulation of the uPA system in RCC. In 786-O RCC cells expressing the wild-type (wt) VHL gene, we measured a 3-fold higher overall urokinase activity than in 786-O cells expressing a mutant VHL gene or lacking VHL. uPA mRNA and protein levels were higher in cells with wt VHL compared with cells with mutant VHL or lacking VHL. In addition, PAI-1 mRNA and protein levels were dramatically increased in 786-O cells with mutant VHL or lacking VHL, compared with cells expressing wt VHL. Our results provide further evidence that the VHL gene plays an important role in the process of angiogenesis by regulation of plasmin-mediated proteolysis of the extracellular matrix and may explain why VHL-induced RCCs grow slowly and metastasize relatively late.     

uPA/uPAR downregulation inhibits radiation-induced migration, invasion and angiogenesis in IOMM-Lee meningioma cells and decreases tumor growth in vivo

Meningioma is a well-known tumor of the central nervous system, and is treated by surgical resection and/or radiation. Recently, ionizing radiation has been shown to enhance invasiveness of surviving tumor cells, and several proteolytic enzyme molecules, including urokinase plasminogen activator (uPA), seem to be upregulated after radiation. uPA and its receptor (uPAR) have been strongly implicated in tumor invasion, angiogenesis and progression. Hence, the tumor-associated uPA-uPAR system is considered a potential target for cancer therapy. In the present study, we show that radiation increases uPA levels in the IOMM-Lee meningioma cells, and subsequently, increases tumor invasion, migration and angiogenesis in vitro. Studies with signaling molecule inhibitors AG1478, U0126 and SB203580 (specific inhibitors of EGFR, MEK1/2 and p38 respectively) showed inhibition of uPA levels in both basal and irradiated-IOMM-Lee cells. The PI3K inhibitor (LY294002) and the AKT inhibitor (AKT inhibitor IV) also partially decreased uPA expression, whereas SP600125, a JNK inhibitor, did not affect uPA levels in either radiated or non-radiated cells. Further, a bicistronic plasmid construct with small interfering RNA (siRNA) against uPA and its receptor inhibited tumor invasion, migration and angiogenesis in radiation-treated IOMM-Lee cells. In addition, siRNA against uPA and its receptor inhibited subcutaneous tumor growth in athymic nude mice in combination with radiation in a synergistic manner. Thus, the specific targeting of proteases via RNA interference could augment the therapeutic effect of radiation and prevent the adverse effects resulting from tumor cells that receive sublethal doses of radiation within the tumor mass.     

The insulin-like growth factor-1 elevates urokinase-type plasminogen activator-1 in human breast cancer cells: a new avenue for breast cancer therapy

Tumor recurrence is a common problem in the treatment of breast cancer. In breast cancer, the expression of high protein levels of the insulin-like growth factor-1 receptor (IGF-1R) and urokinase-type plasminogen activator-1 (uPA) is strongly associated with breast cancer recurrence and decreased survival. The expression of uPA by tumors is thought to not only stimulate tumor invasion but also facilitate angiogenesis. In this study, our goal was to address whether IGF-1R could influence the expression of the extracell ular matrix proteases, matrix metalloproteinase (MMP), or uPA thus allowing a selective advantage for tumor invasion and concomitant neovascularization. Initially, we determined whether or not insulin-like growth factor (IGF)-1 regulated the production MMP or uPA in the human breast cancer MDA-MB-231 cells. There was no increase in MMP activity when the cells were treated with IGF-1 (10 ng/mL) for 24 h. In contrast, uPA mRNA and protein were induced in a time-dependent manner. Furthermore, clones expressi ng a dominant negative inhibitor of IGF-1R termed 486stop had less uPA mRNA, and the clones were less invasive through Matrigel. Taken together, these data illustrate that IGF-1R stimulates uPA production. Hence, these two prognostic indicators may be interrelated, suggesting they may function in a synergistic manner to facilitate local tumor invasion as well as angiogenesis. Our data suggest that disruption of IGF-1 signaling in breast cancer may lead to breast cancer prevention and intervention by decreasing uPA expression.     

Evaluate the Expression of uPA, PAI-1 in Human Gastric Cancer and its Correlation with the Angiogenesis by the Application of Tissue Microarray

OBJECTIVE To investigate the expression of urokinase-type plasminogen (uPA), its inhibitor-1 (PAI-1) mRNA and its protein in human gastric cancer and to find out the relationship among the tumor differentiation, angiogenesis, and other clinical pathologic factors.METHODS In situ hybridization (ISH) was used to get the uPA, PAI-lmRNA in 110 cases with human gastric cancer in 2-tissue microarray (TMA). Immunohistochemical staining (S-P method) for uPA, PAI-1 protein and CD34 were performed in the 110 cases in 2 TMA.RESULTS The expression of the uPA, PAI-lmRNA and their protein happened in the cytoplasm of gastric cancer cells were induced by the poor differentiation of the GC, and the expression of uPA had an increasing trend while the expression of the PAI-1 had a decreasing trend. The microvessel density (MVD) had a positive correlation with the clinical stages and the significant relationship with the lymph node metastasis (P < 0.05). The MVD in uPA positive group was significantly higher than those in uPA negative group (P < 0.05). The expression of PAI-1 has no correlation neither with the clinical stages nor the lymph node metastasis.CONCLUSION The uPA play an important role in invasion and metastasis of GC through promoting angiogenesis. Interdicting the secretion and function of the uPA may allow the target therapy against the tumor invasion. As a new high-throughput technology the tissue microarray is a valuable way to be used in clinical treatment.     

胰腺癌组织中血管内皮生长因子和尿激酶型血纤维蛋白溶菌酶原活化剂基因表达与血管生成的关系及临床意义

目的探讨胰腺癌组织中血管内皮生长因子(VEGF)和尿激酶型血纤维蛋白溶菌酶原活化剂(uPA)表达与血管生成的关系及其临床意义。方法采用免疫组织化学法检测30例胰腺癌组织及6例正常胰腺组织中VEGF和uPA表达情况,分析其与肿瘤组织微血管密度(MVD)的关系。结果胰腺癌组织中VEGF和uPA的阳性表达率分别为53.3%和63.3%。胰腺癌中的MVD明显高于正常组织(P=0.017)。VEGF和uPA表达与MVD有关(P<0.05)。MVD在Ⅰ、Ⅱ期和Ⅲ期胰腺癌组间表达差异有统计学意义(F=4.297,P=0.047),VEGF表达与肿瘤有无淋巴结转移有关(2=4.852,P=0.028)。VEGF在Ⅰ、Ⅱ、Ⅲ期胰腺癌肿瘤组织中表达差异有统计学意义(2=6.914,P=0.032)。uPA在肿瘤大小中的表达差异有统计学意义(2=410.435,P=0.001)。MVD与生存期之间存在负相关(r=0.472,P=0.017)。组织分化程度是影响胰腺癌生存期的危险因素。结论血管生成在胰腺癌的发生、发展过程中起重要作用,VEGF和uPA在胰腺癌组织中过度表达可为肿瘤细胞的浸润创造条件。抗血管生成治疗可能有助于提高胰腺癌的治疗效果。