硫酸乙酰肝素、肝素酶及其与肿瘤转移的关系

细胞外基质和基底膜的降解是癌细胞穿透组织屏障发生转移的重要步骤。硫酸乙酰肝素蛋白聚糖是细胞外基质和基底膜的组成成分,其多糖侧链可以被葡萄糖苷内切酶--肝素酶,特异性识别并切割,以破坏细胞外基质和基底膜的完整性,促进肿瘤转移。临床上肿瘤患者肝素酶高表达与肿瘤恶性程度和转移发生密切相关。深入了解硫酸乙酰肝素、肝素酶及它们与肿瘤转移相关的作用机制有助于我们寻找肿瘤治疗的新思路。本文将从硫酸乙酰肝素的合成调控、功能、肝素酶的转录和活性调节、肝素酶表达与肿瘤患者的临床特征,以及硫酸乙酰肝素、肝素酶与肿瘤转移的关系进行综述。     

血小板、基质金属蛋白酶与肿瘤转移

血小板除参与正常的止血过程外还具有很多病理和生理作用。血小板活化后可以分泌基质金属蛋白酶（matrix metalloproteinases,MMPs）。MMPs属于Zn^2＋和Ca^2＋依赖的内肽酶家族,能特异性与细胞外基质成分相结合并降解细胞外基质。MMPs降解基底膜中的主要成分Ⅳ型胶原,是肿瘤转移发生必不可少的关键步骤。血小板能够与肿瘤细胞结合并促进肿瘤转移,而MMPs在血小板促进肿瘤转移过程中发挥了重要的作用。     

肿瘤抑制基因RECK的功能及与肿瘤侵袭转移的关系

RECK是新近发现的肿瘤抑制基因,与肿瘤的侵袭转移能力密切相关.该文介绍RECK的功能、与肿瘤侵袭转移的关系及其临床意义.     

乙酰肝素酶及在肿瘤治疗中的应用

乙酰肝素酶(Heparanase,Hpa)是哺乳动物体内唯一能够裂解硫酸乙酰肝素蛋白多糖的酶。通过破坏细胞外基质及基底膜结构的完整性,释放胞外基质上的各种生长因子,与肿瘤的转移、侵袭密切相关。目前的研究表明Hpa在大多数中晚期肿瘤中都有表达,尤其在恶性肿瘤中异常高表达,而Hpa表达的下调可以抑制肿瘤细胞的转移,可以作为一种抗肿瘤转移相关靶点用于中晚期肿瘤的治疗。综述了Hpa的结构与功能、对肿瘤转移的促进作用及在肿瘤治疗中的应用情况。     

窖蛋白-1、基质金属蛋白酶-2与乳腺肿瘤的侵袭和转移

窖蛋白(caveolin)是分子量为21～24 kD的整合膜蛋白,是胞膜窖(caveolae)的标志性结构分子,其家族成员窖蛋白-1(caveolin-1,Cav-1)参与细胞内许多重要的生命活动.近来研究发现,窖蛋白-1与乳腺上皮细胞转化及乳腺癌的发生密切相关.基质金属蛋白酶(matrix metalloproteinases,MMPs)是基质降解代谢的主要酶类,几乎能降解细胞外基质和基底膜的所有成分,其家族成员明胶酶A(MMP-2)在乳腺癌的浸润和转移过程中起重要作用.新近发现,窖蛋白-1与基质金属蛋白酶-2在胞膜窖中共定位,窖蛋白-1通过抑制基质金属蛋白酶-2的激活来抑制乳腺癌的侵袭和转移,起到肿瘤抑制因子的作用.本文对窖蛋白-1与基质金属蛋白酶-2各自在乳腺肿瘤侵袭转移中的作用及两者关系的研究进行综述.     

综述: 整合素相关微环境调控肿瘤转移

整合素是肿瘤微环境的重要组成部分,是广泛存在于细胞膜表面的黏附分子,可以识别并结合细胞外基质中相应的配体,参与许多重要的生理过程,包括肿瘤转移．整合素可以促进肿瘤转移的各个阶段,肿瘤微环境也会反过来影响整合素的表达,从而促进癌症的发生发展．     

乙酰肝素酶促进骨肉瘤细胞增殖和侵袭的体外研究

目的:探讨通过基因转染正向调节HPSE-1,体外对骨肉瘤细胞系恶性特质的影响.方法:转染HPSE-1基因至骨肉瘤细胞系MG-63,检测HPSE-1 mRNA和蛋白水平的表达,进一步应用MTT试验和Transwell侵袭试验观察稳定转染的细胞的增殖力和侵袭力的影响.结果:成功建立稳定转染HPSE-1基因的MG-63细胞系MG-63-HPSE,且该细胞系在mRNA和蛋白水平均发现HPSE-1表达增高,MTT和Transwell试验结果发现MG-63-HPSE细胞的增殖力和侵袭力均明显高于对照组.结论:基因转染后过表达HPSE-1的骨肉瘤细胞系体外表现出增强的增殖和侵袭活性.     

整合素在肿瘤转移中的作用及治疗应用

肿瘤转移是由多种分子参与、涉及多个信号通路的复杂的过程,也是肿瘤主要致死原因.整合素是一类粘附分子受体,参与细胞-细胞、细胞-细胞外基质之间相互作用,进而调控细胞转移、侵袭、生存、凋亡、增殖和分化等过程.大量研究表明,整合素在肿瘤转移过程中发挥重要作用.目前,在多种肿瘤中发现整合素表达以及相关信号通路调控发生异常,这会...     

肝素对P选择素介导的肿瘤转移的抑制作用

肝素是一种常见的抗凝药,临床治疗和动物试验中发现肝素还具有抗肿瘤转移的作用,能显著提高肿瘤患者的生存率。在肝素多种抗肿瘤相关的生物活性中,竞争性抑制P选择素介导的肿瘤细胞的黏附作用最为关键,决定了肝素抗肿瘤转移能力的大小,这种与肝素的抗凝机制不同。通过对肝素分子基团进行化学修饰可以消除其副作用的危险,得到具有抗肿瘤转移活性的肝素衍生物。     

整合素与肿瘤的转移与血管生成

整合素是一类介导细胞与细胞外基质及细胞与细胞间黏附的细胞黏附分子受体,肿瘤细胞与胞外基质的相互作用对肿瘤的生成及转移有着重要的影响,整合素在肿瘤的生成、侵袭、转移以及肿瘤血管的生成过程中起着重要的作用。本文对整合素的结构、功能,以及它在肿瘤的血管生成过程中的作用,它与细胞外基质间的相互关系做了介绍。     

Adaptive F-Actin Polymerization and Localized ATP Production Drive Basement Membrane Invasion in the Absence of MMPs

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Comparison of basement membrane matrix degradation by purified proteases and by metastatic tumor cells

We have examined the nature of biochemical degradation of an isolated basement membrane matrix (bovine lens capsule) using different methodologies. The first strategy was quantitation of the release of surface-bound 125I and a second the documentation by SDS-PAGE of the appearance of putative cleavage products and the loss of high-molecular-weight components from the matrix. Basement membrane matrix bands resolved on SDS-PAGE were identified by their protease sensitivities as well as by Western immunoblots using monoclonal antibodies developed for this study. Radioiodinated components were found predominantly at positions on the gel equivalent to 160-200 kd and 400 kd proteins. Since these labeled moieties were sensitive to bacterial collagenase digestion and stained with anticollagen type IV antibodies, they were determined to represent various configurations of collagen type IV. Several other lower-molecular-weight bands also stained with the anticollagen IV antibodies. Monoclonal antibodies reactive with laminin exhibited a complex staining pattern on the gels, which included the expected 200 and 400 kd components. We confirmed that lens capsule basement membrane contained only a single heparan sulfate glycosaminoglycan species, and tumor cell-induced glycosaminoglycan degradation within the basement membrane matrix was detected using cellulose acetate electrophoresis. Distinctive putative cleavage products were resolved on SDS-PAGE gels from matrices subjected to digestion by a variety of purified proteases as well as by metastatic tumor cells or their conditioned media. Tumor cells of different histiotypes produced different characteristic cleavage patterns, suggestive of the existence of several pathways of matrix degradation. Overall, primary tumor cells exhibited a greater degradative activity towards the basement membrane matrix than did long-term tissue culture-passaged cells. The same tumor cell line could exhibit considerably different patterns of both protein and glycosaminoglycan degradation depending on recent culture history. The relevance of these biochemical studies to the pathogenesis of malignant neoplasms is shown by: 1) the evaluation of degradative activities of B16 tumor cell populations exhibiting enhanced lung-colonizing phenotypes, and 2) the ability of a known antimetastatic moiety with antiprotease activity (Haementeria leech species salivary gland extract) to protect matrix components from degradation by tumor cell-conditioned medium.     

Modulation of microvascular growth and morphogenesis by reconstituted basement membrane gel in three-dimensional cultures of rat aorta: A comparative study of angiogenesis in Matrigel,collagen, fibrin,and plasma clot

Summary Rings of rat aorta cultured in Matrigel, a reconstituted gel composed of basement membrane molecules, gave rise to three-dimensional networks composed of solid cellular cords and occasional microvessels with slitlike lumina. Immunohistochemical and ultrastructural studies showed that the solid cords were composed of endothelial sprouts surrounded by nonendothelial mesenchymal cells. The angiogenic response of the aortic rings in Matrigel was compared to that obtained in interstitial collagen, fibrin, or plasma clot. Morphometric analysis demonstrated that the mean luminal area of the microvascular sprouts and channels was significantly smaller in Matrigel than in collagen, fibrin, or plasma clot. The percentage of patent microvessels in Matrigel was also markedly reduced. Autoradiographic studies of³H-thymidine-labeled cultures showed reduced DNA synthesis by developing microvessels in Matrigel. The overall number of solid endothelial cords and microvessels was lower in Matrigel than in fibrin or plasma clot. A mixed cell population isolated from Matrigel cultures formed a monolayer in collagen or fibrin-coated dishes but rapidly reorganized into a polygonal network when plated on Matrigel. The observation that gels composed of basement membrane molecules modulate the canalization, proliferation, and organization into networks of vasoformative endothelial cells in three-dimensional cultures supports the hypothesis that the basement membrane is a potent regulator of microvascular growth and morphogenesis. This work was supported by grants from the W. W. Smith Charitable Trust and grants CA14137 and HL43392 from the National Institutes of Health, Bethesda, MD.     

Characterization of a new tissue-engineered human skin equivalent with hair

Summary We designed a new tissue-engineered skin equivalent in which complete pilosebaceous units were integrated. This model was produced exclusively from human fibroblasts and keratinocytes and did not contain any synthetic material. Fibroblasts were cultured for 35 d with ascorbic acid and formed a thick fibrous sheet in the culture dish. The dermal equivalent was composed of stacked fibroblast sheets and exhibited some ultrastructural organization found in normal connective tissues. Keratinocytes seeded on this tissue formed a stratified and cornified epidermis and expressed typical markers of differentiation (keratin 10, filaggrin, and transglutaminase). After 4 wk of culture, a continuous and ultrastructurally organized basement membrane was observed and associated with the expression of laminin and collagen IV and VII. Complete pilosebaceous units were obtained by thermolysin digestion and inserted in this skin equivalent in order to assess the role of the transfollicular route in percutaneous absorption. The presence of hair follicles abolished the lag-time observed during hydrocortisone diffusion and increased significantly its rate of penetration in comparison to the control (skin equivalent with sham hair insertion). Therefore, this new hairy human skin equivalent model allowed an experimental design in which the only variable was the presence of pilosebaceous units and provided new data confirming the importance of hair follicles in percutaneous absorption.     

A basement membrane-associated glycoprotein from skeletal muscle

We have isolated a major glycoprotein that appears to be associated with rat skeletal muscle basement membrane. We determined that the glycoprotein was part of the muscle cell surface complex when we found it to be enriched in preparations of muscle ghosts. We isolate the glycoprotein from homogenized muscle preextracted with 4 M and 8 M urea. It elutes as a major component in the presence of 8 M urea/50 mM 2-mercaptoethanol. Its apparent molecular weight on sodium dodecyl sulfate gels is 130,000. Amino acid analysis indicates that it is not a collagen but that it does contain small amounts of hydroxyproline and hydroxylysine. There may be collagenous domains in the glycoprotein molecule, for it is cleaved into three fragments by purified bacterial collagenase. Immunoperoxidase staining confirms that the 130,000-dalton protein is localized at the surface of adult skeletal muscle cells. It is probably a general basement membrane-associated glycoprotein because we found material immunologically cross-reactive with the muscle glycoprotein in basement membrane regions of kidney, liver, brain, and small intestine. We have shown the glycoprotein to be distinct from fibronectin, laminin, and types I, III, IV, and V collagens in enzyme-linked immunosorbent assays.     

Biological activities of laminin

Laminin is a multifunctional protein with diverse biological activities. Like fibronectin, it can influence cell adhesion, growth, morphology, differentiation, migration, and agglutination as well as the assembly of the extracellular matrix. Laminin primarily affects cells of epithelial origin, and the response varies depending on the cell. Because most differentiated cells are difficult to maintain in culture, laminin may be an important supplement in studies on cell differentiation in vitro.