Essential fatty acids and their metabolites as modulators of stem cell biology with reference to inflammation, cancer, and metastasis

Stem cells are pluripotent and expected to be of benefit in the management of coronary heart disease, stroke, diabetes mellitus, cancer, and Alzheimer's disease in which pro-inflammatory cytokines are increased. Identifying endogenous bioactive molecules that have a regulatory role in stem cell survival, proliferation, and differentiation may aid in the use of stem cells in various diseases including cancer. Essential fatty acids form precursors to both pro- and anti-inflammatory molecules have been shown to regulate gene expression, enzyme activity, modulate inflammation and immune response, gluconeogenesis via direct and indirect pathways, function directly as agonists of a number of G protein-coupled receptors, activate phosphatidylinositol 3-kinase/Akt and p44/42 mitogen-activated protein kinases, and stimulate cell proliferation via Ca(2+), phospholipase C/protein kinase, events that are also necessary for stem cell survival, proliferation, and differentiation. Hence, it is likely that bioactive lipids play a significant role in various diseases by modulating the proliferation and differentiation of embryonic stem cells in addition to their capacity to suppress inflammation. Ephrin Bs and reelin, adhesion molecules, and microRNAs regulate neuronal migration and cancer cell metastasis. Polyunsaturated fatty acids and their products seem to modulate the expression of ephrin Bs and reelin and several adhesion molecules and microRNAs suggesting that bioactive lipids participate in neuronal regeneration and stem cell proliferation, migration, and cancer cell metastasis. Thus, there appears to be a close interaction among essential fatty acids, their bioactive products, and inflammation and cancer growth and its metastasis.     

Imaging of human mesenchymal stromal cells: homing to human brain tumors

Human mesenchymal stromal cells (hMSC) can be used as a drug delivery vehicle for the treatment of GBM. However, tracking the migration and distribution of these transplanted cells is necessary to interpret therapeutic efficacy. We compared three labeling techniques for their ability to track the migration of transplanted hMSC in an orthotopic mouse xenograft model. hMSC were labeled with three different imaging tags (fluorescence, luciferase or ferumoxide) for imaging by fluorescence, bioluminescence or magnetic resonance imaging (MRI), respectively. hMSC were labeled for all imaging modalities without the use of transfection agents. The labeling efficacy of the tags was confirmed, followed by in vitro and in vivo migration assays to track hMSC migration towards U87 glioma cells. Our results confirmed that the labeled hMSC retained their migratory ability in vitro, similar to unlabeled hMSC. In addition, labeled hMSC migrated towards the U87 tumor site, demonstrating their retention of tumor tropism. hMSC tumor tropism was confirmed by all three imaging modalities; however, MRI provides both real time assessment and the high resolution needed for clinical studies. Our findings suggest that ferumoxide labeling of hMSC is feasible, does not alter their migratory ability and allows detection by MRI. Non invasive tracking of transplanted therapeutic hMSC in the brain will allow further development of human cell based therapies.     

Migration rules: tumours are conglomerates of self-metastases

Tumours are heterogeneous populations composed of different cells types: stem cells with the capacity for self-renewal and more differentiated cells lacking such ability. The overall growth behaviour of a developing neoplasm is determined largely by the combined kinetic interactions of these cells. By tracking the fate of individual cancer cells using agent-based methods in silico, we apply basic rules for cell proliferation, migration and cell death to show how these kinetic parameters interact to control, and perhaps dictate defining spatial and temporal tumour growth dynamics in tumour development. When the migration rate is small, a single cancer stem cell can only generate a small, self-limited clone because of the finite life span of progeny and spatial constraints. By contrast, a high migration rate can break this equilibrium, seeding new clones at sites outside the expanse of older clones. In this manner, the tumour continually ‘self-metastasises''. Counterintuitively, when the proliferation capacity is low and the rate of cell death is high, tumour growth is accelerated because of the freeing up of space for self-metastatic expansion. Changes to proliferation and cell death that increase the rate at which cells migrate benefit tumour growth as a whole. The dominating influence of migration on tumour growth leads to unexpected dependencies of tumour growth on proliferation capacity and cell death. These dependencies stand to inform standard therapeutic approaches, which anticipate a positive response to cell killing and mitotic arrest.     

Migration of renal carcinoma cells is dependent on protein kinase Cdelta via beta1 integrin and focal adhesion kinase

Migration and adhesion of tumor cells are essential prerequisites for the formation of metastases in malignant diseases. Protein kinase C (PKC) has been shown to regulate cell migration, adhesion and proliferation. In order to identify a connection between PKC isoforms and tumor progression in renal cell carcinoma (RCC), the influence of PKC isoforms on cell migration, adhesion and proliferation and possible influences of the activity of integrins and focal adhesion kinase (FAK) were analyzed in RCC cells. The experiments were performed in the RCC cell line CCF-RC1 after pre-incubation of the cells with the PKC inhibitors GF109203X, GO6976, RO31-8220 and rottlerin. Cell migration and adhesion were assessed through chemotaxis analysis and adhesion to an endothelial monolayer, respectively. Cell proliferation was analysed by a BrdU incorporation assay. The expression and activity of beta1 integrins and FAK were analysed by Western blot analysis. GF109203X reduced cell migration to 69%, the activity of beta1 integrins to 63% and FAK expression to 82% compared to untreated cells. Rottlerin reduced cell migration in a concentration-dependent manner to 36%, cell proliferation to 81%, expression and activity of beta1 integrins to 72 and 79%, and expression and activity of FAK to 56 and 76% of untreated cells, respectively. RO31-8220 also reduced the expression and activity of beta1 integrins as well as the expression of FAK to 84, 66 and 66% of untreated cells, respectively. GO6976 reduced the expression of FAK to 60% of untreated cells. Cell migration was only slightly reduced by GO6976 to 84% of untreated cells, and cell adhesion remained uninfluenced. These findings show a critical role of PKCdelta in the regulation of tumor cell migration, which seems to be caused by affecting the expression and activity of beta1 integrins and FAK. These results can provide a basis for new strategies in preventing metastases of renal cell carcinoma.     

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.     

运动系统中干细胞衰老及其机制研究进展

干细胞（ stem cell ）是一种具有自我更新和多向分化潜能的未成熟细胞。根据干细胞来源不同，通常分为3类：胚胎干细胞（ embryonic stem cell ）、成体干细胞（ adult stem cell ）及多能诱导干细胞（ induced pluripotent stem cell ）[1]。几乎在所有成体组织和器官中均发现干细胞的存在。这些干细胞在参与组织修复与再生，维持内稳态平衡中发挥至关重要的作用[2]。随着干细胞移植治疗研究的进展，干细胞衰老（ stem cell aging ）现象逐渐引起广泛重视[2-3]。这一发现彻底颠覆了人们对干细胞的传统认识。既往被认为＂无限活力＂和＂无所不能＂的干细胞，同成熟细胞一样也面临着衰老问题，从而限制了干细胞移植治疗的应用。目前认为干细胞衰老是机体衰老的主要原因，是疾病发生和发展的重要机制，也是干细胞治疗领域迫切需要面对的问题[4]。本研究仅就运动系统中干细胞衰老现象及其相关机制做如下综述。     

The mitotic functions of integrin-linked kinase

The cytoskeleton is composed of three major constituents: actin filaments, intermediate filaments and microtubules. These are vital for numerous normal cellular processes including cell spreading and migration, intracellular organelle transport, mechanical strength, mitosis and cytokinesis. Deregulation of cytoskeletal components can lead to cells developing several oncogenic phenotypes; for example increased migration and invasiveness, defects in cellular morphogenesis and genetic instabilities due to errors in mitosis and cytokinesis. Integrin-linked kinase (ILK) is a protein with well established roles in regulating actin cytoskeletal reorganization, survival, proliferation, cell migration, invasion and epithelial to mesenchymal transition, and is therefore essential to normal cell physiology. In addition, ILK is overexpressed or deregulated in a number of human cancers and when experimentally overexpressed leads to the acquisition of a number of oncogenic phenotypes, some of which, such as increased cell migration, are actin-dependent. Here we shall focus on the recent finding that ILK also regulates the microtubule cytoskeleton and is involved in mitotic spindle organization. Therefore its deregulation may also lead to errors in cell division causing genomic instability, potentially further contributing to cancer development. In light of these findings, the therapeutic potential of the anti-mitotic effects of genetic or pharmacological inhibition of ILK will also be discussed.     

Fully automated three-dimensional tracking of cancer cells in collagen gels: determination of motility phenotypes at the cellular level

We developed a fully automated three-dimensional cell tracking system that quantified the effect of extracellular matrix components on the infiltration and migration of tumor cells. The three-dimensional trajectories of two highly invasive cell lines, the human HT-1080 fibrosarcoma and the human MDA-MB-231 adenocarcinoma, were determined for long-term infiltration in plain or Matrigel-containing collagen type I gels. We modeled the trajectories with a novel formulation of the continuous Markov chain model that can distinguish between the tendencies for infiltration or lateral motion. Parameters such as the speed of subpopulations, the persistence of motion in certain directions, the turning frequency of the cells, the ultimate direction of motion, and the cell distribution with the infiltration depth were obtained to quantify the migration and infiltration at the cellular level. Distinct migratory and infiltration phenotypes were identified for the two cell types that were significantly dependent on gel composition. The HT-1080 cell line expressed a high motility phenotype on the plain collagen gel surface. The Matrigel-containing gel significantly enhanced the infiltration and the turning frequency of the HT-1080 cells. This study shows that tumor cell infiltration and migration are dynamic processes that depend significantly on the cell type and the microenvironment.     

唾液腺腺样囊性癌来源的外泌体促进癌细胞的增殖、迁移及侵袭

目的:探索人唾液腺腺样囊性癌不同细胞系分泌的外泌体对其癌细胞增殖、迁移及侵袭能力的影响。方法:使用ExoEasy Maxi Kit (Qiagen,Hilden,Germany)试剂盒提取外泌体,通过透射电镜、纳米粒子跟踪分析（NTA）、蛋白免疫印迹Western blotting技术鉴定提取的肿瘤外泌体。并在外泌体的干预下,采用CCK-8法、平板克隆形成实验、细胞划痕及Transwell实验检测细胞增殖、迁移及侵袭能力。结果:透射电镜及纳米粒子跟踪分析（NTA）检测显示:提取的外泌体主要直径在30~150 nm之间,其形态呈典型的“茶托型”结构;Western blotting检测到外泌体特异性标志蛋白CD9、CD63及TSG101呈阳性表达。CCK-8法及平板克隆实验显示唾液腺腺样囊性癌来源的外泌体可增强其癌细胞增殖能力（P<0.05）。细胞划痕及Transwell实验表明其外泌体可增强癌细胞迁移及侵袭能力（P<0.05）。结论:唾液腺腺样囊性癌不同细胞系均分泌外泌体。唾液腺腺样囊性癌外泌体可增强其癌细胞增殖、迁移及侵袭能力。     

Examination of gap junctional,intercellular communication by in situ electroporation on two co‐planar indium‐tin oxide electrodes

Gap junctions are plasma membrane channels between neighboring cells. We previously described a powerful technique where gap junctional, intercellular communication (GJIC) of adherent cells can be examined by in situ electroporation on a slide, part of which is coated with electrically conductive and transparent indium‐tin oxide. An electric pulse is applied through an electrode placed on the cells in the presence of the tracking dye, Lucifer yellow (LY). The pulse causes LY''s penetration into the cells growing on the conductive part of the slide, and the subsequent migration of the dye to the non‐electroporated cells growing on the non‐conductive area is microscopically observed under fluorescence illumination. Although this technique is adequate for a number of cell lines, the turbulence generated as the electrode is removed can cause cell detachment, which makes GJIC examination problematic. In this communication, we describe a slide configuration where junctional communication can be examined in the absence of an upper electrode: Cells are grown on two co‐planar electrodes separated by a barrier which diverts the electric field, rendering it vertical to the cell layer. The elimination of an upper electrode is especially valuable for the electroporation of sensitive cells, such as terminally differentiated adipocytes. This technique can also be used for the introduction of other non‐permeant molecules such as peptides or siRNA, followed by examination of the cellular phenotype or gene expression levels in situ.     

PLC and PI3K Pathways are Important in the Inhibition of EGF-lnduced Cell Migration by Gefitinib (‘lressa’, ZD1839)

BACKGROUND: Expression of epidermal growth factor receptor (EGFR) by human breast cancer tissues is associated with poor clinical response. The EGFR tyrosine kinase inhibitor (EGFR-TKI), gefitinib ('Iressa', ZD1839), is a leading example of a molecular targeted agent, and has an anti-proliferative effect on various cancer cells. But the details of the anti-cancer effect and mechanism have not been elucidated. We studied the anti-cancer effect of gefitinib in breast cancer cell lines and the intracellular pathway downstream of EGFR associated with cell migration. METHODS: In this study, we analysed the anti-proliferative and anti-migratory effect of gefitinib in EGFR (+) breast cancer cell lines by WST-1 analysis and chemotaxis chamber analysis. We analyzed several intracellular phosphorylated pathways which are activated by mitogen activated kinases (extracellular signal-regulated protein kinase 1 and 2: MEK), phosphatidylinositol 3'-kinase (PI3K) and phpspholipase C (PLC), by blocking those pathways using inhibitors of each kinase, and also investigated the effects on the phosphorylation of myosin light chain (MLC). RESULTS: Gefitinib inhibited proliferation in most of these cell lines. MDA-MB231 was shown to be resistant. Furthermore, proliferation of MDA-MB231 cells was not affected by EGF stimulation, but migration of MDA-MB231 cells was significantly inhibited. PI3K and PLC inhibitors blocked EGF-stimulated cell migration and MLC phosphorylation, but the MEK inhibitor did not influence cell migration. CONCLUSIONS: Gefitinib has an anti-migratory effect on MDA-MB231 that results in an anti-proliferative effect. PI3K and PLC are important for the migration of MDA-MB231 cells, and gefitinib may inhibit migration by blocking these signalling pathways.     

In vitro and in vivo imaging of cell migration: two interdepending methods to unravel metastasis formation

Metastasis development requires the migratory activity of tumor cells. It is therefore important to understand the molecular mechanisms of this migration in order to prevent metastasis development, which is the pernicious step in most solid tumor diseases. A lot of methods have been invented to investigate tumor cell migration, but not all are equally suited and no method alone is able to deliver a complete picture of tumor cell migration. We herein suggest a combination of three-dimensional in vitro and in vivo methods for the investigation of tumor cell migration and summarize the knowledge, which has been reached so far.     

Human mesenchymal stem cells and their use in cell‐based therapies

The human population is increasingly facing various diseases, including types of cancer, that cannot be cured with conventional drugs. Advanced drug targeting of tumor cells is also often impossible when treating highly invasive and infiltrative tumors such as glioblastoma or pulmonary cancer, because of tumor cells' high migration and invasiveness. Pluripotent human mesenchymal stem cells (hMSCs) have been extensively studied, and strategies are being proposed for treating “incurable” cancers and injury/disease‐affected organs. Because of their own intrinsic properties, involving homing and immunomodulatory potency, hMSCs could be used as an excellent cell/drug delivery vehicle in those cell‐based therapies. Their unprecedented use has been shadowed, however, by their spontaneous transformation, which links them to cancer‐initiating cells during tumor development. How malignant initiation proceeds in vivo, and what are the exact characteristics of the cancer‐initiating cells, still remain to be investigated. In the present review, the authors summed up the most recent knowledge about hMSC characteristics, their malignant transformation, and outlined the possibilities of their safe use in novel cell‐based therapies. Cancer 2010. © 2010 American Cancer Society.     

Homing behaviour of the malignant cell clone in multiple myeloma

Multiple myeloma (MM) represents a B cell malignancy characterised by the presence of a monoclonal population of end-stage B cells in the bone marrow. Although fully matured bone marrow plasma cells are the predominant cell type in MM, there is much evidence that also more immature B cells are included in the malignant cell clone which are considered to be the myeloma precursor cells. The fact that these cells are detectable in the blood circulation and that their number increases with disease progression, makes it very likely that they represent the component of the tumour clone that mediates disease dissemination. This implies that these cells must have the potential to extravasate and home to the bone marrow environment. Like the migration mechanisms used by normal leukocytes and/or metastatic tumour cells of non-haematopoietic origin, it can be assumed that this bone marrow homing process is mediated by adhesive interactions and chemotactic signals provided by the microenvironment of the tumour. Once in the bone marrow compartment, myeloma cells will receive the appropriate signals to grow and survive. This aspect of tumour-homing is found to be the result of a functional interplay between the myeloma cells and the surrounding microenvironment, involving the action of several cytokines and adhesion molecules. In the end phase of the disease, myeloma cells can lose their stroma-dependency resulting in extramedullary tumour growth. We review normal B cell homing and discuss molecular mechanisms that determine the homing behaviour of the malignant cell clone in MM.     

小鼠黑色素瘤某些生物学特性与其侵袭潜能的相关性研究

目的 研究具有相同起源而转移能力不同的小鼠黑色素瘤细胞系（B16、B16F10、B16BL6）的某些生物学特性与其侵袭潜能的相关性。方法 用重组基质膜实验考察细胞的侵袭能力;用分光光度法测定黑色素瘤细胞的黑色素含量;利用细胞运动记录分析系统研究细胞在三维胶原基质中的运动状态;用明胶底物酶谱法分析细胞分泌Ⅳ型胶原酶的能力;用端粒重复扩增（TRAP）－PCR法测定细胞的端粒酶活性。结果 B16B6力B16F10具有较高的侵袭能力,其运动能力及分泌Ⅳ型胶原酶的能力亦较强,但B16F10的黑色素含量却较低;端粒酶活性在三者之间无明显差异。结论在所研究的小鼠黑色素瘤不同亚系的声东击西 些生物学特性中,侵袭能力与细胞运动能力、分泌Ⅳ型胶原酶的能力之间有较好的相关性,而与黑色素含量及端粒酶活性无直接相关性。     

Inhibition of migration and invasion of carcinoma cells by urokinase-derived antagonists of alphavbeta5 integrin activation

We previously showed that, while binding to urokinase receptor (uPAR) through its growth factor domain (GFD, residues 1-49), urokinase (uPA) can engage alphavbeta5 integrin through an internal domain (CP, residues 132-158). This novel uPA/alphavbeta5 interaction promotes cytoskeletal rearrangements and directional cell migration (Franco et al., J Cell Sci 2006;119:3424-34). We now show that treatment of cells with phosphomimic uPA (uPA138E/303E, serine 138 and 303 substituted with glutamic acid) strongly inhibits matrix-induced cell migration. Unlike uPA, binding of uPA138E/303E to cell surface did not induce F-actin enriched protruding structures and caused a 5-fold reduction in cell translocation speed, as determined by video tracking of living cells. Inhibition of migration was found to be independent of uPAR, since uPA variants lacking the GFD domain, but carrying the relevant Ser to Glu substitutions were as effective inhibitor as uPA138E/303E. Through several independent approaches, we established that the phosphomimics specifically bind to alphavbeta5 integrin through the CP region carrying the S138E mutation. This interaction blocks integrin activation, as determined by a decreased affinity of alphavbeta5 to vitronectin and a reduced association of the beta5 cytoplasmic tail with talin. Finally, stable expression of uPA138E/303E in human squamous carcinoma cells prevented tumor cell invasion in vivo. Thus, when expressed in cancer cells, the inhibitory phosphomimic effect was dominant over the effect of endogenously produced uPA. These results shed light on the regulation of cell migration by uPA phosphorylation and provide a realistic opportunity for a novel antiinvasive/metastatic therapeutic intervention.     

The neurotransmitter gamma-aminobutyric acid is an inhibitory regulator for the migration of SW 480 colon carcinoma cells

Gamma-aminobutyric acid (GABA) is the inhibitory neurotransmitter in the brain, also playing a role in diseases like epilepsy. We now show that this inhibitory neurotransmitter can also reduce migratory activity in SW 480 colon carcinoma cells. GABA reduced the norepinephrine-induced migratory activity of these cells within a three-dimensional collagen matrix to spontaneous migration levels, as was analyzed by time-lapse videomicroscopy. This inhibitory effect of GABA was mediated by the serpentine receptor GABA(B) and was intracellularly transduced by a decrease of the cyclic AMP concentration. Cancer cell migration is thus regulated by neurobiological signals, opening new possibilities for pharmacological agonists in cancer therapy.     

Detection and Relevance of Minimal Disease in Lymphomas

The detection and clinical relevance of minimal disease in non-Hodgkin's lymphoma (NHL) and Hodgkin's disease (HD) is reviewed. Relevant aspects of the basic biology of these diseases are introduced, including the interactions of NHL with bone marrow stromal cells and the consequences of suppressed apoptosis and induced chemoresistance which might explain why minimal lymphoma in bone marrow is a surrogate predictor of a poor clinical outcome. In contrast, NHL cells isolated from stroma, for example mobilized into blood by cytokine, may be more susceptible to apoptosis and clinically less significant. The possible role of angiogenesis in facilitating early metastasis to the bone marrow is considered. Methods of detecting minimal NHL are reviewed and differences in predictive reliability of tumor detected by culture methods versus molecular techniques which identify clonal bcl-2 or antigen receptor rearrangements are discussed. The role of detection of HD by analysis of unique rearrangements of the immunoglobulin heavy and light chain genes is discussed as is the possibility that Reed–Sternberg (RS) cells can be detected molecularly as well as grown in culture from blood and apheresis harvests of patients. It appears that patients with cells resembling RS cells in their harvest do less well following high dose therapy and transplantation and additional studies of this topic are warranted. Future developments including quantitative monitoring of disease burden by real-time automated PCR and the application of genetic profiling to identify genetic markers specific to the tumor and which, potentially can predict prognosis is suggested. Also, the problems which may arise in attempts to monitor the impact of newer therapies such as anti-lymphoma antibodies and vaccines which may preferentially deplete tumor cells from blood and marrow are considered. The past 10 years has witnessed dramatic progress in the application of techniques to monitor minimal lymphoma. This technology has helped demonstrate the success of some new therapeutic approaches e.g. antibody and vaccine therapies, and served to emphasize the failure of others, for example, stem cell selection to purge lymphoma from patient harvests. Technologically, the field is not yet mature and further evolution may be expected.     

Roles oflow-density lipoprotein receptor-related protein 1 intumors

Low-density lipoprotein receptor-related protein 1 (LRP1, also known as CD91), a multifunctional endocytic and cell signaling receptor, is widely expressed on the surface of multiple cell types such as hepatocytes, ifbroblasts, neu-rons, astrocytes, macrophages, smooth muscle cells, and malignant cells. Emerging invitro and invivo evidence demonstrates that LRP1 is critically involved in many processes that drive tumorigenesis and tumor progression. For example, LRP1 not only promotes tumor cell migration and invasion by regulating matrix metalloproteinase (MMP)-2 and MMP-9 expression and functions but also inhibits cell apoptosis by regulating the insulin receptor, the serine/threonine protein kinase signaling pathway, and the expression of Caspase-3. LRP1-mediated phosphorylation of the extracellular signal-regulated kinase pathway and c-jun N-terminal kinase are also involved in tumor cell proliferation and invasion. In addition, LRP1 has been shown to be down-regulated by microRNA-205 and methylation ofLRP1 CpG islands. Furthermore, a novel fusion gene,LRP1-SNRNP25, promotes osteosarcoma cell invasion and migration. Only by understanding the mechanisms of these effects can we develop novel diagnostic and therapeutic strategies for cancers mediated by LRP1.