中心体相关调节蛋白及其异常与肿瘤发生的研究进展

中心体是动物细胞的重要细胞器,作为动物细胞中首要的微管组织中心（microtu-bule-organizing center,MTOC）,在细胞的生命活动中起着重要的作用。各种不同形式的中心体异常会造成细胞中微管分布的紊乱,进而引起细胞骨架的异常和染色体分离障碍。许多位于中心体处的蛋白对于中心体微管组织中心功能实现发挥着重要的作用,它们的异常同很多疾病的发生息息相关。更为重要的是越来越多的证据表明,不同来源肿瘤细胞中存在有各种中心体的异常,并且这些异常对于肿瘤的发生、发展和预后都有着紧密的联系。因而研究中心体微管组织中心功能和研究实现这些功能的相关调节蛋白,对于肿瘤的早期诊断和抗肿瘤药物的开发提供了重要的依据。     

LIMK的研究进展

LIM-激酶（LIMK）家族包含两个成员:LIM激酶1（LIMK1）及LIM激酶2（LIMK2）。LIMK1主要参与肿瘤细胞的侵袭迁移过程,其磷酸化作用可引起细胞骨架肌动蛋白动力学变化及微管解聚,在许多恶性肿瘤组织如前列腺肿瘤、乳腺癌、肺癌、恶性胶质瘤细胞等高表达。LIMK2可能参与细胞骨架的改建,可促进肌动蛋白的合成,磷酸化丝切蛋白从而使之失去解聚多聚体纤维状肌动蛋白(F-actin)的能力。本文对LIMK 的结构、功能、在肿瘤及其他疾病中的研究作一综述,LIMK可能是一个很有潜力的遏制肿瘤侵袭转移的治疗靶点。     

Rho GTP酶在ω-3多不饱和脂肪酸抑制人前列腺癌PC-3细胞转移中的作用

背景与目的:近年来,多不饱和脂肪酸对肿瘤发生、发展影响的研究备受关注.本实验主要观察两种ω-3多不饱和脂肪酸(ω-3 polyunsaturated fatty acid,ω-3 PUFA)二十碳五烯酸(eicosapentaenoic acid,EPA)和二十二碳六烯酸(docosahexaenoic acid,DHA)对人前列腺癌细胞株PC-3转移的影响,并通过检测ω-3 PUFA对细胞内Rho GTP酶蛋白表达及细胞骨架重组影响,揭示Rho GTP酶在ω-3 PUFA抑制肿瘤转移中的作用.方法:MTT法观察ω-3 PUFA对PC-3细胞增殖能力的影响,体外粘附实验、侵袭实验和迁移实验观察ω-3 PUFA对肿瘤细胞转移的影响.Western blot法检测ω-3 PUFA对与细胞骨架重组相关的RhoA、Rac1、Rac2和Cdc42蛋白表达的影响.免疫荧光细胞化学法标记微丝和微管,激光共聚焦扫描显微镜观察ω-3 PUFA对细胞骨架重组的影响.结果:EPA及DHA均能抑制PC-3细胞增殖,增殖抑制率均随处理浓度增大和作用时间延长而增加.与对照组比较,60μmol/L的EPA或DHA处理后的PC-3细胞体外粘附性、侵袭性和迁移性均显著下降(P＜0.05).ω-3 PUFA能显著下调Rac1、Rac2和Cdc42蛋白表达(P＜0.05),并能明显影响细胞内微丝和微管细胞骨架的结构和分布.结论:ω-3 PUFA能够通过下调Rho GTP酶基因表达,抑制Rho GTP酶对细胞骨架重组的调控,导致细胞骨架结构改变,削弱肿瘤细胞的粘附性、侵袭性和迁移性,抑制PC-3细胞的转移.     

EZRIN蛋白与妇科肿瘤侵袭转移关系研究进展

Ezrin (埃兹蛋白)是ERM (ezrin∕radixin∕moesin,埃兹蛋白/根蛋白/膜突蛋白)蛋白家族成员之一,是膜细胞骨架连接蛋白,通过介导膜与细胞骨架的连接,Ezrin调节细胞形态形成、运动、黏附以及细胞信号转导等多项细胞活动,而这些细胞活动与肿瘤的发生、发展及浸润转移等密切相关.多项研究表明Ezrin的表达水平与多种肿瘤的侵袭力、转移、临床预后有密切关系.Ezrin可能与妇科肿瘤病程进展密切相关,但相关研究较少.     

Rho蛋白在消化系统恶性肿瘤侵袭与转移方面的研究

Rho蛋白是一种小分子G蛋白(small G protein,CTPase),其最重要的功能是调节肌动蛋白细胞骨架,从而参与细胞迁移、调控肿瘤转移,因此,Rho蛋白与消化系统恶性肿瘤侵袭与转移的关系,已成为研究的前沿领域之一.     

Rho蛋白与肿瘤

Rho蛋白(RhoGTP酶)家族与肿瘤关系密切,在其调节子和效应子作用下,影响肿瘤的发生、生长、侵袭和转移.因此Rho蛋白和它们的效应子可能是有效的抗肿瘤靶点,针对这些靶点可以研究有效的药物或基因治疗物质,干涉Rho蛋白的功能,促进肿瘤临床治疗的发展.     

Rho蛋白与肿瘤

Rho蛋白(Rho GTP酶)家族与肿瘤关系密切，在其调节子和效应子作用下，影响肿瘤的发生、生长、侵袭和转移。因此Rho蛋白和它们的效应子可能是有效的抗肿瘤靶点，针对这些靶点可以研究有效的药物或基因治疗物质，干涉Rho蛋白的功能，促进肿瘤临床治疗的发展。     

癌相关成纤维细胞在肿瘤疗效预测和预后判断中的应用价值

摘 要：癌相关成纤维细胞（CAF）是肿瘤微环境中重要的细胞成分,不仅为肿瘤的发生、发展提供条件,还帮助癌细胞侵袭、转移、形成耐药性和产生放射抗性等,因此有人提出CAF可作为抗肿瘤治疗的新靶标。研究发现,CAF及其相关蛋白和基因检测指标,还可作为恶性肿瘤药物疗效预测以及患者预后判断的重要参考。全文就癌相关成纤维细胞在肿瘤疗效预测和预后判断中的应用价值作一综述。     

缺氧诱导因子-1靶向治疗研究进展

抑制缺氧诱导因子-1(HIF-1)的表达,阻断缺氧信号的传递,已经成为肿瘤治疗的新思路。一些以HIF-1为靶点的抗肿瘤药物正在进行研究和开发。主要的小分子抑制剂包括拓扑替康、103DSR、氧化还原抑制荆、微管细胞骨架抑制剂、热休克蛋白90抑制剂、PI3K-Akt-mTOR信号途径抑制剂、HIF-1α转录活性调节剂等。这些小分子抑制剂在体内外实验中能够抑制肿瘤细胞的HIF-1表达,但是临床试验研究还处于起步阶段。进一步阐明HIF-1与肿瘤发生发展的相关机制将有利于HIF-1靶向治疗的研究。     

美国肿瘤研究的近况

美国近年来肿瘤研究取得了可喜的进展。本文简要介绍了肿瘤生物学基础的几个方面,包括生长因子、抑瘤基因、侵袭与转移的进展;对肿瘤病因与预防研究方面着重介绍了有关胃癌研究以及化学预防药物的内容;同时对新抗癌药物、抗肿瘤转移药物、细胞因子抗肿瘤作用也进行了综述。     

Ezrin蛋白在肿瘤转移中的作用及机制研究

肿瘤转移是肿瘤恶化及死亡的主要原因,近年来研究发现,许多microRNA(miR)、蛋白分子、细胞信号转导通路等均可介导肿瘤迁移侵袭.Ezrin蛋白又称细胞绒毛蛋白,属埃兹蛋白/根蛋白/膜突蛋白(Ezrin/Radixin/Moesin,ERM)家族最早发现的一员,广泛分布于人体细胞内,是细胞骨架与细胞膜之间的连接蛋白...     

Role of tumor cytoskeleton and membrane glycoprotein IRGpIIb/IIIa in platelet adhesion to tumor cell membrane and tumor cell-induced platelet aggregation

Components of the tumor cell cytoskeleton (i.e., microtubules, microfilaments, and intermediate filaments) have been reported to affect metastatic ability, since disruption of these components leads to a decrease in metastasis. One mechanism of metastasis which has not been previously considered is the decreased interaction of tumor cells with platelets. We present evidence that disruption of the tumor cell cytoskeleton decreases the ability of tumor cells to aggregate homologous platelets. This effect is dependent upon the disruption of microfilaments/intermediate filaments but not disruption of microtubules. In addition, tumor cell platelet interactions require the lateral mobility of specific receptors (i.e., clustering) on the tumor cell plasma membrane. A membrane glycoprotein immunologically related to the platelet glycoprotein IIb/IIIa complex was identified on Walker 256 carcinosarcoma cells using specific polyclonal and monoclonal antibodies and Northern blot analysis using complementary DNA probes for IIb and IIIa. Mobility of this receptor is dependent upon tumor cell microfilaments/intermediate filaments, but not microtubules. Furthermore, treatment of tumor cells with specific antibodies to the platelet glycoprotein IIb/IIIa complex inhibits tumor cell-platelet interaction at the macroscopic level (i.e., aggregation) and at the ultrastructural level (i.e., platelet adhesion to the tumor cell surface). These results suggest that this immunologically related glycoprotein IIb/IIIa is a receptor for platelet binding to the tumor cell surface, an event which precedes overt platelet aggregation and is dependent upon an intact tumor cell microfilament and intermediate filament network. Therefore, the decreased metastasis observed by others following disruption of the tumor cell cytoskeleton may be due, in part, to a decreased tumor cell-platelet interaction.     

Fatty acid modulation of tumor cell-platelet-vessel wall interaction

Summary Prostaglandins and other eicosanoids have been studied extensively in their physical, biochemical, biophysical and pharmacological aspects. However, studies on their role in tumor progression, especially metastases are relatively recent. Following a brief overview of the history of discovery and metabolism of eicosanoids and other fatty acids, we discuss the functions of these fatty acids (with emphasis on prostacyclin, thromboxane A₂, 12-hydroxyeicosatetraenoic acid and 13-hydroxyoctadecadienoic acid) in cell transformation, tumor promotion and particularly in tumor cell metastasis. The relation between these monohydroxy fatty acids and tumor cell metastasis is discussed from three different perspectives, i.e., their effects on tumor cells, on platelets and on endothelial cells. The mechanism of these effects are then addressed at cell adhesion molecule, motility, protease, cell cytoskeleton, protein kinase and eicosanoid receptor levels. Finally, regulation of three key enzymes which generate eicosanoids (phospholipase, prostaglandin endoperoxide synthase and lipoxygenase) is explored.     

TPM3-ALK expression induces changes in cytoskeleton organisation and confers higher metastatic capacities than other ALK fusion proteins

Translocations of the anaplastic lymphoma kinase (ALK) gene result in the production of a number of oncogenic ALK fusion proteins implicated in tumour development. We have previously shown that X-ALK fusion proteins have differential effects on the proliferation, transformation, and invasion properties of NIH3T3 cells in vitro. In the present study, we have investigated the metastatic potential of various X-ALK expressing cell lines using an experimental lung metastasis assay. We have shown that TPM3-ALK expression bestows higher metastatic capacities than other X-ALK fusion proteins and in addition, that TPM3-ALK fusion protein expression specifically induces changes in cell morphology and cytoskeleton organisation. Co-immunoprecipitation studies demonstrate a specific interaction between TPM3-ALK and endogenous tropomyosin. Together the specific actions of TPM3-ALK on the cytoskeleton organisation offer an interesting hypothesis with respect to the higher cell motility and metastatic potential of this fusion protein.     

Cell volume regulation in cancer cell migration driven by osmotic water flow

Cancer metastasis is the most frequent cause of death for patients with cancer. The main current treatment for cancer metastasis is chemotherapy targeting cancer cells’ ability to proliferate. However, some types of cancer cells show resistance to chemotherapy. Recently, cancer cell migration has become the subject of interest as a novel target of cancer therapy. Cell migration requires many factors, such as the cytoskeleton, cell‐matrix adhesion and cell volume regulation. Here, we focus on cell volume regulation and the role of ion/water transport systems in cell migration. Transport proteins, such as ion channels, ion carriers, and aquaporins, are indispensable for cell volume regulation under steady‐state conditions and during exposure to osmotic stress. Studies from the last ~25 years have revealed that cell volume regulation also plays an important role in the process of cell migration. Water flow in accordance with localized osmotic gradients generated by ion transport contributes to the driving force for cell migration. Moreover, it has been reported that metastatic cancer cells have higher expression of these transport proteins than nonmetastatic cancer cells. Thus, ion/water transport proteins involved in cell volume regulation and cell migration could be novel therapeutic targets for cancer metastasis. In this review, after presenting the importance of ion/water transport systems in cell volume regulation, we discuss the roles of transport proteins in a pathophysiological context, especially in the context of cancer cell migration.     

Regulation of cancer cell motility through actin reorganization

Cell migration is a critical step in tumor invasion and metastasis, and regulation of this process will lead to appropriate therapies for treating cancer. Cancer cells migrate in various ways, according to cell type and degree of differentiation. The different types of cell migration are regulated by different mechanisms. Reorganization of the actin cytoskeleton is the primary mechanism of cell motility and is essential for most types of cell migration. Actin reorganization is regulated by Rho family small GTPases such as Rho, Rac, and Cdc42. These small GTPases transmit extracellular chemotactic signals to downstream effectors. Of these downstream effectors, Wiskott-Aldrich syndrome protein (WASP) family proteins are key regulators of cell migration. Activated WASP family proteins induce the formation of protrusive membrane structures involved in cell migration and degradation of the extracellular matrix. Inhibition of Rho family small GTPase signaling suppresses the migration and invasion of cancer cells. Thus, control of cell migration via the actin cytoskeleton provides the possibility of regulating cancer cell invasion and metastasis.     

The Janus‐faced role of ezrin in “linking” cells to either normal or metastatic phenotype

In the majority of eukaryotic cells, the ezrin, radixin and moesin (ERM) proteins are involved in many physiologic functions including regulation of actin cytoskeleton, control of cell shape, adhesion, motility and modulation of signal transduction pathways. In a previous study, we used a dominant negative ezrin‐mutant to address ezrin involvement in remodeling of actin cytoskeleton and subsequently we depicted ezrin key role in melanoma cell migration and progression. Herein, we highlight recent advances on ezrin involvement in the metastatic phenomenon, including also some more neglected ezrin‐related functions. Novel molecular processes driven by ezrin activation include: phagocytosis, acquisition of resistance to chemotherapeutics and triggering of programmed cell death signals. Recent data support an integrated role of ezrin also in development of tumor malignancy. On one hand, ezrin may be responsible of deranged execution of specific known functions such as adhesion and motility and on the other, it may also participate to unique metastatic determinants, through the establishment of aberrant linkages with tumor‐related proteins. For instance, ezrin misslocalization, absence or deranged activity has started to be correlated with tumor progression in many tumors of different species, including humans. Concomitantly, ezrin may act simultaneously as a regulatory or deregulatory chaperon in both normal and tumor cells. It is still to be established whether this Janus‐faced feature of ezrin is due to some unknown transforming Zelig‐like property or to the fact that a tumor‐associated molecule preferentially links to ezrin thus distracting it from its normal connections. However, the contribution of ezrin functional deregulation to the acquisition of the metastatic phenotype appears clear and ezrin or ezrin aberrant associations may represent good candidates for future anti‐tumor therapies. © 2009 UICC     

Orthotopically implanted SCID mouse model of human lung cancer suitable for investigating metastatic potential and anticancer drug effects

To evaluate the effects of drugs in clinical settings, an animal model of lung cancer similar to clinical cancer is necessary. Our previous studies described an SCID mouse model using orthotopic implantation of the human lung cancer cell line which mimicked the lymph node metastasis of patients with lung cancer. In this study, we made animal models that reflected various metastatic forms of lung cancer in humans. We applied our procedure to 6 lung cancer cell lines. Suspensions of 2.0 x 10(4) cancer cells were injected into the left lung of SCID mice. We evaluated the mRNA expressions of 52 proteins related to the metabolism of and resistance to anticancer drugs of each tumor cell line and its orthotopically implanted tumor using a customized cDNA array. Three lung cancer cell lines had the potential of lymphogenous metastasis and 3 cell lines had the potential of hematogenous metastasis in this model system. The A549 line showed multiple metastases, and Ma2 line showed solitary metastasis. The expression of 52 genes in each implanted tumor was closely correlated with that in each cell lines (correlation coefficients: 0.8883-0.9533), and the gradient of the regression line was more than 0.9. This model was similar to the metastatic form in patients with lung cancer. The similar expression of proteins in each tumor cell line in vitro and implanted tumor in vivo gives an advantage in evaluating the effects of molecular-targeted drugs and the relationship between specific genes and tumor potential in preclinical studies.     

Rac-WAVE2 signaling is involved in the invasive and metastatic phenotypes of murine melanoma cells

WAVEs (WASP-family verprolin-homologous proteins) regulate the actin cytoskeleton through activation of Arp2/3 complex. As cell motility is regulated by actin cytoskeleton rearrangement and is required for tumor invasion and metastasis, blocking actin polymerization may be an effective strategy to prevent tumor dissemination. We show that WAVEs, especially WAVE2, are essential for invasion and metastasis of melanoma cells. Malignant B16F10 mouse melanoma cells expressed more WAVE1 and WAVE2 proteins and showed higher Rac activity than B16 parental cells, which are neither invasive nor metastatic. The effect of WAVE2 silencing by RNA interference (RNAi) on the highly invasive nature of B16F10 cells was more dramatic than that of WAVE1 RNAi. Membrane ruffling, cell motility, invasion into the extracellular matrix, and pulmonary metastasis of B16F10 cells were suppressed by WAVE2 RNAi. WAVE2 RNAi also had a profound effect on invasion induced by a constitutively active form of Rac (RacCA). In addition, ectopic expression of both RacCA and WAVE2 in B16 cells resulted in further increase in the invasiveness than that observed in B16 cells expressing only RacCA. Thus, WAVE2 acts as the primary effector downstream of Rac to achieve invasion and metastasis, suggesting that suppression of WAVE2 activity holds a promise for preventing cancer invasion and metastasis.     

The tumor microenvironment in hepatocellular carcinoma: current status and therapeutic targets

A growing body of literature highlights the cross-talk between tumor cells and the surrounding peri-tumoral stroma as a key modulator of the processes of hepatocarcinogenesis, epithelial mesenchymal transition (EMT), tumor invasion and metastasis. The tumor microenvironment can be broadly classified into cellular and non-cellular components. The major cellular components include hepatic stellate cells, fibroblasts, immune, and endothelial cells. These cell types produce the non-cellular components of the tumor stroma, including extracellular matrix (ECM) proteins, proteolytic enzymes, growth factors and inflammatory cytokines. The non-cellular component of the tumor stroma modulates hepatocellular carcinoma (HCC) biology by effects on cancer signaling pathways in tumor cells and on tumor invasion and metastasis. Global gene expression profiling of HCC has revealed that the tumor microenvironment is an important component in the biologic and prognostic classification of HCC. There are substantial efforts underway to develop novel drugs targeting tumor-stromal interactions. In this review, we discuss the current knowledge about the role of the tumor microenvironment in pathogenesis of HCC, the role of the tumor microenvironment in the classification of HCC and efforts to develop treatments targeting the tumor microenvironment.