群体性侵袭与肿瘤的研究进展

群体性侵袭是肿瘤细胞重要的运动形式之一,其在肿瘤侵袭转移过程中的作用日益受到关注。群体性迁移是胚胎发育过程中重要的运动模式。与此相似,近年来研究显示癌细胞以群体方式侵袭转移在恶性肿瘤中普遍存在。群体性侵袭参与癌细胞播散和转移的机制正逐渐被揭示。对肿瘤群体性侵袭的深入研究,有助于发现新的抑制肿瘤侵袭转移的干预途径。     

Cofilin 1在肿瘤中的表达及意义

Cofilin 1（丝切蛋白1）是肌动蛋白相关蛋白,对肌动蛋白介导的细胞运动和骨架的改变起重要的调节作用。近年研究发现Cofilin 1的活化与肿瘤细胞的恶性侵袭性质有关。Cofilin 1的局部激活可以诱导片状伪足的形成,并影响肿瘤细胞运动的方向,从而增强肿瘤细胞的运动和迁移。最新研究成果显示,抑制或者增强Cofilin 1的活性可以减少肿瘤细胞的侵袭和迁移。Cofilin 1和p-Cofilin1在肿瘤细胞中的表达存在一个动态平衡,打破这个平衡可以直接抑制细胞的迁移和侵袭。本文对Cofilin 1的结构、功能、调控机制及平衡机制与肿瘤侵袭转移和上皮间质转化(EMT)以及肿瘤耐药性的关系作一综述。     

Versican在肿瘤中的生物学作用

Versican是蛋白聚糖家族之一,其表达水平增高与许多肿瘤的不良预后有关。肿瘤的类型不同,其表达部位也不同,可以表达在肿瘤细胞本身,也可以表达在肿瘤周围的间质中。Versican在细胞黏附、增殖、迁移和血管生成中都起作用,这些特点与肿瘤的侵袭和转移有关。这些功能特点有赖于Versican的中间氨基葡聚糖结合区以及两末端的球状区域与许多细胞外基质和细胞表面成分的相互作用。本文对最近发现的调控Versican表达的机制以及它在肿瘤侵袭和转移中的生物学作用作一综述。     

MicroRNA-34 a对多种肿瘤细胞迁移的影响及其作用机制探讨

MicroRNA-34a是p53信号通路的核心成分,在多种肿瘤中表达下调,被认为是一种抑癌的microRNA,并且与肿瘤干细胞有着密切的联系。MicroRNA-34a可直接抑制多种信息调控因子、细胞周期蛋白的表达,进而抑制细胞增殖、抑制细胞迁移和侵袭、促进细胞衰老和凋亡,从而达到抑癌效果。细胞迁移是肿瘤细胞侵袭和转移的先决条件,是肿瘤发生发展的重要过程。MicroRNA-34a的低表达常见于乳腺癌、前列腺癌、膀胱癌、胃癌、结肠癌、骨癌等,这种低表达往往与细胞迁移能力增强有关,最终加剧肿瘤转移扩散。本文总结了近期关于microRNA-34a对不同种类肿瘤细胞迁移的影响及其作用机制,并进行了分析与归纳。     

鼻咽癌侵袭与转移相关基因的研究进展

0引言鼻咽癌是头颈部常见恶性肿瘤之一,其局部复发及远处转移一直是影响鼻咽癌患者长期存活的主要因素。而肿瘤的侵袭与转移是受多种因素调控的复杂过程,涉及肿瘤细胞增殖、肿瘤新血管形成、肿瘤细胞黏附、细胞凋亡以及肿瘤细胞迁移运动等一     

血小板通过上调NF-κB信号通路增强乳腺癌循环肿瘤细胞的侵袭和迁移能力

目的:探讨血小板接触对乳腺癌循环肿瘤细胞（circulating tumor cells,CTCs）侵袭和迁移能力的影响。方法:利用CytoQuestTM CR抓取乳腺癌患者血液中的循环肿瘤细胞,通过RT-PCR检测Wnt2基因表达水平。通过Western blot检测肿瘤细胞上皮细胞-间充质转化（epithelial-mesenchymal transition,EMT）以及NF-κB信号通路相关蛋白的表达情况。通过细胞划痕、Transwell实验检测血小板的直接接触对肿瘤细胞侵袭和迁移能力的影响。通过封闭乳腺癌细胞中NF-κB的表达,观察NF-κB信号通路在肿瘤细胞侵袭和迁移能力中的重要作用。结果:RT-PCR结果显示,乳腺癌患者血液中的CTCs内Wnt2基因高表达。Western blot结果显示,血小板与乳腺癌细胞的直接接触增加了肿瘤细胞的上皮间质化进程,并诱导激活了肿瘤细胞的NF-κB通路。细胞划痕和Transwell实验结果显示,与血小板共培养可促进乳腺癌细胞的侵袭和迁移。此外,通过封闭乳腺癌细胞中NF-κB基因,可以降低Wnt2的表达,抑制肿瘤细胞的上皮间质化进程,减弱乳腺癌细胞的侵袭和迁移能力。结论:血小板与肿瘤细胞的直接接触促进了乳腺癌循环肿瘤细胞的侵袭和迁移能力,封闭NF-κB信号通路可能是抑制乳腺癌循环肿瘤细胞侵袭和迁移能力的有效策略。     

塔斯品碱衍生物TPD7对乳腺癌细胞迁移和侵袭的抑制作用

目的:探讨塔斯品碱衍生物TPD7对乳腺癌细胞MCF-7和ZR-75-30细胞迁移和侵袭的影响,阐明TPD7抑制细胞迁移和侵袭可能的作用机制。方法:采用细胞划痕法、Transwell小室侵袭法检测MCF-7和ZR-75-30细胞的迁移和侵袭。采用Western blot法检测MMP9、β-catenin及c-Myc的蛋白表达。RT-PCR法检测β-catenin及c-Myc的mRNA表达。结果:TPD7对MCF-7细胞和ZR-75-30细胞迁移和侵袭均有显著抑制作用,且下调MMP9、β-catenin、c-Myc的蛋白表达和mRNA表达,呈剂量依赖性。结论:TPD7抑制乳腺癌MCF-7和ZR-75-30细胞迁移和侵袭,可能是通过Wnt信号通路抑制上皮-间质转化。     

Rho蛋白与细胞骨架调节的细胞运动

细胞迁移是肿瘤细胞浸润和转移的关键环节,细胞骨架的重组过程是细胞发生移动的基础,受多种信号分子的调节.肿瘤细胞可以表现出多种类型的运动方式,而每种细胞运动方式可由不同的分子机制调节,其中细胞骨架蛋白actin的重组在肿瘤细胞的运动中至关重要.Rho蛋白家族的小GTP酶蛋白在肿瘤细胞中被活化,可以通过调节细胞骨架actin的重组,引起细胞侵袭、转移.其活化方式包括:Rho蛋白及其调节子的活化突变、灭活突变和Rho家族蛋白和作用分子表达水平的改变等,通过自身活化将细胞外的趋化信号传递给细胞内的下游效应分子.导致细胞骨架依赖性的反应,影响细胞的移动功能.因而,对Rho家族的小GTP酶蛋白信号进行有效的抑制可以有效的抑制肿瘤细胞的侵袭和转移过程,是肿瘤治疗的新方法.     

miR-769对食管鳞癌细胞增殖、侵袭和迁移能力及紫杉醇耐药性的影响

目的:探讨hsa-miR-769（miR-769）在食管鳞癌组织中的表达及其对癌细胞增殖、侵袭和迁移能力及紫杉醇耐药性的影响。方法:通过生物信息学技术挖掘,我们对肿瘤相关的hsa-miR-769（miR-769）的表达进行了深入研究,进而进行临床样本的验证,并通过细胞生物学和分子生物学研究对其作用机制进行了进一步探索。结果:公共数据库的挖掘结果显示miR-769在食管癌组织中表达异常升高,且在临床样本中我们观察到了相同的升高异常,通过细胞实验和分子生物学实验,我们发现miR-769调控肿瘤细胞的增殖、侵袭和迁移能力,同时引起肿瘤细胞的上皮间质转化过程发生改变,后续的研究中,我们成功构建了紫杉醇耐药的食管鳞癌细胞系,并发现miR-769在食管鳞癌对于紫杉醇的获得性耐药中起到了重要作用。结论:miR-769影响食管鳞癌细胞的增殖、侵袭和迁移能力及对紫杉醇的耐药性,本研究旨在探索食管鳞癌发生发展的机制,并为食管鳞癌靶向治疗提供了新的潜在靶点。     

自分泌IGF-1/IGF-1R环路促进NK/T细胞淋巴瘤细胞株迁移和侵袭

目的 探讨IGF-1/IGF-1R信号通路对NK/T细胞淋巴瘤(NK/TCL)细胞株迁移和侵袭的作用及其调控机制.方法 采用反转录聚合酶链反应(RT-PCR)及免疫荧光技术检测IGF-1和IGF-1R的表达,Transwell技术观察NK/TCL细胞迁移和侵袭.酶联免疫吸附实验(ELISA)检测MMP-2、MMP-9及TIMP1水平.结果 NK/TCL细胞株SNK-1和SNK-6均表达IGF-1与IGF-1R,而健康人NK细胞不表达IGF-1R.IGF-1R抑制剂显著抑制SNK-1和SNK-6的迁移和侵袭.外源性IGF-1则促进细胞迁移及侵袭,而IGF-1R抑制剂能阻断该效应.IGF-1R下游相关激酶p38、PI3K及JNK的抑制剂均可降低细胞迁移能力.外源性IGF-1可上调MMP-2、MMP-9的分泌水平,IGF-1R抑制剂则抑制MMP-2、MMP-9的分泌.结论 NK/TCL细胞株中存在IGF-1/IGF-1R自分泌环路,并通过IGF-1/IGF-1R通路促进MMP-2、MMP-9分泌及IGF-1R下游p38、PI3K及JNK等激酶促进肿瘤细胞的迁移和侵袭.     

Src activates Abl to augment Robo1 expression in order to promote tumor cell migration

Cell migration is an essential step in cancer invasion and metastasis. A number of orchestrated cellular events involving tyrosine kinases and signaling receptors enable cancer cells to dislodge from primary tumors and colonize elsewhere in the body. For example, activation of the Src and Abl kinases can mediate events that promote tumor cell migration. Also, activation of the Robo1 receptor can induce tumor cell migration. However, while the importance of Src, Abl, and Robo1 in cell migration have been demonstrated, molecular mechanisms by which they collectively influence cell migration have not been clearly elucidated. In addition, little is known about mechanisms that control Robo1 expression. We report here that Src activates Abl to stabilize Robo1 in order to promote cell migration. Inhibition of Abl kinase activity by siRNA or kinase blockers decreased Robo1 protein levels and suppressed the migration of transformed cells. We also provide evidence that Robo1 utilizes Cdc42 and Rac1 GTPases to induce cell migration. In addition, inhibition of Robo1 signaling can suppress transformed cell migration in the face of robust Src and Abl kinase activity. Therefore, inhibitors of Src, Abl, Robo1 and small GTPases may target a coordinated pathway required for tumor cell migration.     

Collective cell movement in primary melanoma explants: plasticity of cell-cell interaction, beta1-integrin function, and migration strategies

Collective cell movement represents an efficient dissemination strategy in neoplastic epithelial and mesenchymal cancer. In primary melanoma explants cultured in three-dimensional collagen lattices, invasive migration of multicellular clusters was dependent on the function of beta1 integrins, as shown by preferential beta1-integrin expression and clustering in a subset of promigratory cells at the leading edge ("guiding cells") and the abrogation of multicellular migration by adhesion-perturbing anti-beta1-integrin antibody. Interference with beta1-integrin function induced complex changes in cluster polarity and cohesion, including development of two or several opposing leading edges, cluster disruption, and the detachment of individual cells followed by beta1-integrin-independent "amoeboid" crawling and dissemination. The conversion from beta1-integrin-dependent collective movement to beta1-integrin-independent single-cell motility suggests efficient cellular and molecular plasticity in tumor cell migration strategies.     

Collective cell migration of thyroid carcinoma cells: a beneficial ability to override unfavourable substrates

Purpose

Tumor cell invasion and metastasis are life threatening events. Invasive tumor cells tend to migrate as collective sheets. In the present in vitro study we aimed to (i) assess whether collective tumor cells gain benefits in their migratory potential compared to single cells and (ii) to identify its putative underlying molecular mechanisms.

Methods

The migratory potential of single and collective carcinoma cells was assessed using video time lapse microscopy and cell migration assays in the absence and presence of seven potential gap junction inhibitors or the Rac1 inhibitor Z62954982. The perturbation of gap junctions was assessed using a dye diffusion assay. In addition, LDH-based cytotoxicity and RT-PCR-based expression analyses were performed.

Results

Whereas single breast, cervix and thyroid carcinoma cells were virtually immobile on unfavourable plastic surfaces, we found that they gained pronounced migratory capacities as collectives under comparable conditions. Thyroid carcinoma cells, that were studied in more detail, were found to express specific subsets of connexins and to form active gap junctions as revealed by dye diffusion analysis. Although all potential gap junction blockers suppressed intercellular dye diffusion in at least one of the cell lines tested, only two of them were found to inhibit collective cell migration and none of them to inhibit single cell migration. In the presence of the Rac1 inhibitor Z62954982 collective migration, but not single cell migration, was found to be reduced up to 20 %.

Conclusions

Our data indicate that collective migration enables tumor cells to cross otherwise unfavourable substrate areas. This capacity seems to be independent of intercellular communication via gap junctions, whereas Rac1-dependent intracellular signalling seems to be essential.

     

微小RNA与乳腺癌细胞的增殖和转移

 乳腺癌的发生是一个多因素参与的阶段性演进过程,微小RNA（miRNA）可通过调节肿瘤细胞的增殖、凋亡和迁移参与肿瘤发生、发展及远处浸润转移。miRNA影响乳腺癌细胞的增殖与转移机制研究将为乳腺癌的诊治提供新的思路。     

A “class action” against the microenvironment: do cancer cells cooperate in metastasis?

The authors review how cancer cells may cooperate in metastasis by means of microenvironmental changes. The main mechanisms underlying this cooperation are clustered migration of cancer cells, extracellular matrix degradation, paracrine loops of released signaling factors and/or induction of adhesion molecules on stromal cells. Another critical factor could be temporal cooperation: successive waves of cancer cells may induce progressive conditioning of the microenvironment. The “class action” of cancer cells against the microenvironment involves successive steps of the metastatic process: invasion of the primary tumor microenvironment, collective migration through the extracellular matrix, blood vessel disruption, vascular or lymphatic tumor emboli, establishment of a premetastatic niche by secreted factors and endothelial precursor recruitment, induction of cell adhesion molecule expression in endothelial cells, extravasation, micrometastasis dormancy and establishment of a new growth in distant sites. As a result, after completion of the metastatic process, the series of microenvironmental changes from the primary tumor to the metastatic site may promote colonization of metastases by nonmetastatic cancer cells of the primary tumor.     

Snail promotes Cyr61 secretion to prime collective cell migration and form invasive tumor nests in squamous cell carcinoma

We previously identified genes associated with Snail-mediated squamous cell carcinoma (SCC) invasiveness, in which we observed significant elevation of Cyr61 expression. In this study, SCC cell lines overexpressing Cyr61 exhibited constitutive activation of Rho A and upregulated invasiveness without the disruption of homophilic cell attachment. Humoral Cyr61 enhanced further production of endogenous Cyr61 by SCC cells, which stimulated collective cell migration and the development of an invasive tumor nest. We propose a Cyr61-dependent model for the development of invasive SCC nest, whereby a subset of tumor cells that highly produce Cyr61 may direct other tumor cells to undergo collective cell migration, resulting in a formation of primary SCC mass.     

Collective cancer cell invasion induced by coordinated contractile stresses

The physical underpinnings of fibrosarcoma cell dissemination from a tumor in a surrounding collagen-rich matrix are poorly understood. Here we show that a tumor spheroid embedded in a 3D collagen matrix exerts large contractile forces on the matrix before invasion. Cell invasion is accompanied by complex spatially and temporally dependent patterns of cell migration within and at the surface of the spheroids that are fundamentally different from migratory patterns of individual fibrosarcoma cells homogeneously distributed in the same type of matrix. Cells display a continuous transition from a round morphology at the spheroid core, to highly aligned elongated morphology at the spheroid periphery, which depends on both β₁-integrin-based cell-matrix adhesion and myosin II/ROCK-based cell contractility. This isotropic-to-anisotropic transition corresponds to a shift in migration, from a slow and unpolarized movement at the core, to a fast, polarized and persistent one at the periphery. Our results also show that the ensuing collective invasion of fibrosarcoma cells is induced by anisotropic contractile stresses exerted on the surrounding matrix.     

Lack of transforming growth factor-β signaling promotes collective cancer cell invasion through tumor-stromal crosstalk

ABSTRACT: INTRODUCTION: Transforming growth factor beta (TGF-β) has a dual role during tumor progression, initially as a suppressor and then as a promoter. Epithelial TGF-β signaling regulates fibroblast recruitment and activation. Concurrently, TGF-β signaling in stromal fibroblasts suppresses tumorigenesis in adjacent epithelia, while its ablation potentiates tumor formation. Much is known about the contribution of TGF-β signaling to tumorigenesis, yet the role of TGF-β in epithelial-stromal migration during tumor progression is poorly understood. We hypothesize that TGF-β is a critical regulator of tumor-stromal interactions that promote mammary tumor cell migration and invasion. METHODS: Fluorescently labeled murine mammary carcinoma cells, isolated from either MMTV-PyVmT transforming growth factor-beta receptor II knockout (TβRII KO) or TβRIIfl/fl control mice, were combined with mammary fibroblasts and xenografted onto the chicken embryo chorioallantoic membrane. These combinatorial xenografts were used as a model to study epithelial-stromal crosstalk. Intravital imaging of migration was monitored ex ovo, and metastasis was investigated in ovo. Epithelial RNA from in ovo tumors was isolated by laser capture microdissection and analyzed to identify gene expression changes in response to TGF-β signaling loss. RESULTS: Intravital microscopy of xenografts revealed that mammary fibroblasts promoted two migratory phenotypes dependent on epithelial TGF-β signaling: single cell/strand migration or collective migration. At epithelial-stromal boundaries, single cell/strand migration of TβRIIfl/fl carcinoma cells was characterized by expression of α-smooth muscle actin and vimentin, while collective migration of TβRII KO carcinoma cells was identified by E-cadherin+/p120+/β-catenin+ clusters. TβRII KO tumors also exhibited a twofold greater metastasis than TβRIIfl/fl tumors, attributed to enhanced extravasation ability. In TβRII KO tumor epithelium compared with TβRIIfl/fl epithelium, Igfbp4 and Tspan13 expression was upregulated while Col1α2, Bmp7, Gng11, Vcan, Tmeff1, and Dsc2 expression was downregulated. Immunoblotting and quantitative PCR analyses on cultured cells validated these targets and correlated Tmeff1 expression with disease progression of TGF-β-insensitive mammary cancer. CONCLUSION: Fibroblast-stimulated carcinoma cells utilize TGF-β signaling to drive single cell/strand migration but migrate collectively in the absence of TGF-β signaling. These migration patterns involve the signaling regulation of several epithelial-to-mesenchymal transition pathways. Our findings concerning TGF-β signaling in epithelial-stromal interactions are important in identifying migratory mechanisms that can be targeted as recourse for breast cancer treatment.