RESUMEN
New experimental tools are urgently required to better understand the metastatic process. The importance of such tools is underscored by the fact that many anti-cancer therapies are generally ineffective against established metastases. This makes a major contribution to the fact that metastatic spread is responsible for over 90% of cancer patient deaths. It was therefore timely that the recent "Seed and Soil: In Vivo Models of Metastasis" conference held in Berlin, Germany (27-29 of November 2017) aimed to give an in-depth overview of the latest research models and tools for studying metastasis, and to showcase recent findings from world-leading metastasis researchers. This Meeting Report summarises the major themes of this ground-breaking conference.
Asunto(s)
Modelos Animales de Enfermedad , Siembra Neoplásica , Neoplasias/patología , Células Madre Neoplásicas/patología , Animales , Congresos como Asunto , Humanos , Metástasis de la NeoplasiaRESUMEN
S100A4 is implicated in metastasis and chronic inflammation, but its function remains uncertain. Here we establish an S100A4-dependent link between inflammation and metastatic tumor progression. We found that the acute-phase response proteins serum amyloid A (SAA) 1 and SAA3 are transcriptional targets of S100A4 via Toll-like receptor 4 (TLR4)/nuclear factor-κB signaling. SAA proteins stimulated the transcription of RANTES (regulated upon activation normal T-cell expressed and presumably secreted), G-CSF (granulocyte-colony-stimulating factor) and MMP2 (matrix metalloproteinase 2), MMP3, MMP9 and MMP13. We have also shown for the first time that SAA stimulate their own transcription as well as that of proinflammatory S100A8 and S100A9 proteins. Moreover, they strongly enhanced tumor cell adhesion to fibronectin, and stimulated migration and invasion of human and mouse tumor cells. Intravenously injected S100A4 protein induced expression of SAA proteins and cytokines in an organ-specific manner. In a breast cancer animal model, ectopic expression of SAA1 or SAA3 in tumor cells potently promoted widespread metastasis formation accompanied by a massive infiltration of immune cells. Furthermore, coordinate expression of S100A4 and SAA in tumor samples from colorectal carcinoma patients significantly correlated with reduced overall survival. These data show that SAA proteins are effectors for the metastasis-promoting functions of S100A4, and serve as a link between inflammation and tumor progression.
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Inflamación/complicaciones , Metástasis de la Neoplasia , Proteínas S100/fisiología , Proteína Amiloide A Sérica/genética , Animales , Línea Celular Tumoral , Neoplasias del Colon/mortalidad , Receptores ErbB/fisiología , Humanos , Ratones , Especificidad de Órganos , Proteína de Unión al Calcio S100A4 , Proteína Amiloide A Sérica/fisiologíaRESUMEN
BACKGROUND: Association studies have implicated the glycosaminoglycan hyaluronan (hyaluronic acid, HA) and its degrading enzymes the hyaluronidases in tumour progression and metastasis. Oligosaccharides of degraded HA have been ascribed a number of biological functions that are not exerted by high-molecular-weight HA (HMW-HA). However, whether these small HA oligosaccharides (sHA) have a role in tumour progression currently remains uncertain due to an inability to analyse their concentration in tumours. METHODS: We report a novel method to determine the concentration of sHA ranging from 6 to 25 disaccharides in tumour interstitial fluid (TIF). Levels of sHA were measured in TIF from experimental rat tumours and human colorectal tumours. RESULTS: While the majority of HA in TIF is HMW-HA, concentrations of sHA up to 6 µg ml(-1) were detected in a subset of tumours, but not in interstitial fluid from healthy tissues. In a cohort of 72 colorectal cancer patients we found that increased sHA concentrations in TIF are associated with lymphatic vessel invasion by tumour cells and the formation of lymph node metastasis. CONCLUSIONS: These data document for the first time the pathophysiological concentration of sHA in tumours, and provide evidence of a role for sHA in tumour progression.
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Adenocarcinoma/metabolismo , Biomarcadores de Tumor/metabolismo , Neoplasias Colorrectales/metabolismo , Líquido Extracelular/metabolismo , Ácido Hialurónico/metabolismo , Adenocarcinoma/secundario , Animales , Línea Celular Tumoral , Neoplasias Colorrectales/patología , Humanos , Metástasis Linfática , Invasividad Neoplásica , Trasplante de Neoplasias , RatasRESUMEN
The tumor microenvironment makes a decisive contribution to the development and dissemination of cancer, for example, through extracellular matrix components such as hyaluronan (HA), and through chemokines that regulate tumor cell behavior and angiogenesis. Here we report a molecular link between HA, its receptor CD44 and the chemokine CXCL12 in the regulation of cell motility and angiogenesis. High-molecular-weight HA (hHA) was found to augment CXCL12-induced CXCR4 signaling in both HepG2iso cells and primary human umbilical vein endothelial cells, as evidenced by enhanced ERK phosphorylation and increased cell motility. The augmentation of CXCR4 signaling translated into increased vessel sprouting and angiogenesis in a variety of assays. Small HA oligosaccharides (sHA) efficiently inhibited these effects. Both siRNA-mediated reduction of CD44 expression and antibodies that block the interaction of CD44 with HA provided evidence that CXCL12-induced CXCR4 signaling depends on the binding of hHA to CD44. Consistently, CD44 and CXCR4 were found to physically interact in the presence of CXCL12, an interaction that could be inhibited by sHA. These findings provide novel insights into how microenvironmental components interact with cell surface receptors in multi-component complexes to regulate key aspects of tumor growth and progression.
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Quimiocina CXCL12/farmacología , Receptores de Hialuranos/metabolismo , Ácido Hialurónico/química , Ácido Hialurónico/farmacología , Receptores CXCR4/metabolismo , Transducción de Señal/efectos de los fármacos , Animales , Movimiento Celular/efectos de los fármacos , Células Hep G2 , Células Endoteliales de la Vena Umbilical Humana/citología , Células Endoteliales de la Vena Umbilical Humana/efectos de los fármacos , Células Endoteliales de la Vena Umbilical Humana/metabolismo , Humanos , Técnicas In Vitro , Ratones , Peso Molecular , Neovascularización Fisiológica/efectos de los fármacosRESUMEN
The Ras association domain family 1 isoform A (RASSF1A) is a tumor suppressor whose inactivation is implicated in the development of many human cancers, including breast carcinomas. Little is known about the tumor-suppressive function of RASSF1A in breast tissue and whether its inactivation is mechanistically involved in the initiation and progression of breast tumors. Here, we show that RASSF1A inhibits breast cancer growth in vivo, and suppresses estrogen receptor (ERα) expression and function. Reconstitution of RASSF1A in MCF7 cells led to decreased ERα levels and reduced sensitivity to estrogen (E2). Concomitantly, we observed decreased expression of Id1 as well as the E2-responsive genes Bcl-2 and c-Myc that cooperatively contribute to the immortalization and transformation of breast epithelial cells. This downregulation was associated with induction of cell-cycle arrest and senescence that constitute early barriers to cancer initiation and progression. Knockdown of ERα showed that downregulation of ERα suffices to increase senescence and inhibit expression of Bcl-2, c-Myc and Id1. However, enforced expression of ERα only partially rescued RASSF1A-mediated growth inhibition and senescence, suggesting that suppression of ERα expression and activity is not the only mechanism by which RASSF1A inhibits growth and survival of breast cancer cells. Ectopic expression of Bcl-2, c-Myc and Id1 had little or no effect on RASSF1A-mediated growth arrest, indicating that RASSF1A acts dominantly over these oncogenes. Mechanistically, RASSF1A was found to suppress ERα expression through Akt1. It also transiently inhibited ERα-induced Ras-MAPK activity after exposure of cells to E2. Together, our data show that RASSF1A acts as a tumor suppressor in ERα+ mammary epithelial cells, in part through inhibiting ERα expression and activity. These findings suggest that RASSF1A has a key role in suppressing the transformation of human breast epithelial cells and ERα+ breast cancer initiation.
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Neoplasias de la Mama/metabolismo , Receptor alfa de Estrógeno/genética , Regulación Neoplásica de la Expresión Génica , Transducción de Señal , Proteínas Supresoras de Tumor/fisiología , Animales , Apoptosis , Neoplasias de la Mama/patología , Puntos de Control del Ciclo Celular , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proliferación Celular , Supervivencia Celular , Senescencia Celular , Estradiol/análogos & derivados , Estradiol/farmacología , Antagonistas de Estrógenos/farmacología , Receptor alfa de Estrógeno/metabolismo , Estrógenos/farmacología , Femenino , Fulvestrant , Expresión Génica , Humanos , Células MCF-7 , Ratones , Ratones Endogámicos NOD , Ratones SCID , Trasplante de Neoplasias , Proteolisis , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismoRESUMEN
Here, we report unbiased screens for genes expressed in metastatic tumor cells that are associated with cell motility. These screens identified Ier2, an immediate early gene of unknown function, as potentially having a role in tumor cell motility and metastasis. Knockdown of Ier2 in 3T3 fibroblasts inhibited their motility upon relief of contact inhibition in monolayer wounding assays. Furthermore, ectopic Ier2 expression promoted the motility and invasiveness of poorly metastatic 1AS pancreatic tumor cells in vitro. Relief of contact inhibition was associated with translocation of the Ier2 protein from the cytoplasm to the nucleus in both 3T3 fibroblasts and 1AS tumor cells. Importantly, ectopic Ier2 expression in 1AS cells stimulated metastasis formation when cells were implanted into experimental animals. Furthermore, we found elevated Ier2 expression in a wide variety of human tumor types. This correlated with poor metastasis-free and overall survival in patients with colorectal adenocarcinomas. Together, these data reveal Ier2 as a new player in the regulation of tumor progression and metastasis, and suggest that Ier2 may be useful prognostically and therapeutically in the management of cancer.
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Movimiento Celular , Neoplasias Colorrectales/mortalidad , Proteínas Inmediatas-Precoces/fisiología , Transactivadores/fisiología , Células 3T3 , Animales , Línea Celular Tumoral , Neoplasias Colorrectales/química , Humanos , Proteínas Inmediatas-Precoces/análisis , Proteínas Inmediatas-Precoces/genética , Metástasis Linfática , Ratones , Invasividad Neoplásica , Linfocitos T/química , Transactivadores/análisis , Transactivadores/genéticaRESUMEN
We have previously performed an unbiased screen to identify genes whose expression is associated with the metastatic phenotype. Secondary screening of these genes using custom microarray chips identified ASAP1, a multi-domain adaptor protein with ADP-ribosylation factor-GAP activity, as being potentially involved in tumor progression. Here, we show that at least three different splice forms of ASAP1 are upregulated in rodent tumor models in a manner that correlates with metastatic potential. In human cancers, we found that ASAP1 expression is strongly upregulated in a variety of tumors in comparison with normal tissue and that this expression correlates with poor metastasis-free survival and prognosis in colorectal cancer patients. Using loss and gain of function approaches, we were able to show that ASAP1 promotes metastasis formation in vivo and stimulates tumor cell motility, invasiveness, and adhesiveness in vitro. Furthermore, we show that ASAP1 interacts with the metastasis-promoting protein h-prune and stimulates its phosphodiesterase activity. In addition, ASAP1 binds to the SH3 domains of several proteins, including SLK with which it co-immunoprecipitates. These data support the notion that ASAP1 can contribute to the dissemination of a variety of tumor types and represent a potential target for cancer therapy.
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Proteínas Adaptadoras Transductoras de Señales/fisiología , Neoplasias Colorrectales/patología , Proteínas Adaptadoras Transductoras de Señales/genética , Empalme Alternativo , Animales , Adhesión Celular , Línea Celular Tumoral , Movimiento Celular , Neoplasias Colorrectales/metabolismo , Neoplasias Colorrectales/mortalidad , Progresión de la Enfermedad , Perfilación de la Expresión Génica , Humanos , Invasividad Neoplásica , Metástasis de la Neoplasia , Ratas , Dominios Homologos srcRESUMEN
Ten years ago the relationship between tumors and the lymphatic system was perceived to be rather passive. Since then, the dramatic increase in our understanding of the molecular biology of lymphatic endothelial cells and the regulation of lymphangiogenesis has revealed that tumors can actively interact with the lymphatics by inducing lymphangiogenesis. In turn, this interaction promotes the entry of tumor cells into the lymphatic vasculature and their subsequent transport to regional lymph nodes, a process that stimulates the formation of metastases. Tumor-induced lymphangiogenesis has thus emerged as an important new target in the fight against metastatic cancer. Nevertheless, there is still much to be learned about the relationship between tumors and the lymphatics that will have important ramifications for the design of clinical trials aimed at the application of anti-lymphangiogenesis therapies in the management of cancer. This Lymphangiogenesis Review focuses on these issues.
Asunto(s)
Linfangiogénesis , Sistema Linfático/patología , Neoplasias/patología , Animales , Regulación Neoplásica de la Expresión Génica , Humanos , Ganglios Linfáticos/patología , Metástasis Linfática/patología , Neoplasias/metabolismo , Neoplasias/terapiaRESUMEN
Histone deacetylases (HDACs) play important roles in transcriptional regulation and pathogenesis of cancer. Thus, HDAC inhibitors are candidate drugs for differentiation therapy of cancer. Here, we show that the well-tolerated antiepileptic drug valproic acid is a powerful HDAC inhibitor. Valproic acid relieves HDAC-dependent transcriptional repression and causes hyperacetylation of histones in cultured cells and in vivo. Valproic acid inhibits HDAC activity in vitro, most probably by binding to the catalytic center of HDACs. Most importantly, valproic acid induces differentiation of carcinoma cells, transformed hematopoietic progenitor cells and leukemic blasts from acute myeloid leukemia patients. More over, tumor growth and metastasis formation are significantly reduced in animal experiments. Therefore, valproic acid might serve as an effective drug for cancer therapy.
Asunto(s)
Diferenciación Celular/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Inhibidores de Histona Desacetilasas , Ácido Valproico/farmacología , Animales , Línea Celular Transformada , Cricetinae , Humanos , Receptores Citoplasmáticos y Nucleares/genética , Receptores de Glucocorticoides/genética , Factores de Transcripción/genética , Transcripción Genética/efectos de los fármacosRESUMEN
The ability to discriminate reliably at the histological level between blood and lymphatic microcapillaries would greatly assist the study of a number of biological and pathological questions and may also be of clinical utility. A structure-function comparison of these types of microcapillary suggests that differences which could function as markers to allow discrimination between blood and lymphatic endothelium should exist. Indeed, to date a variety of such markers have been proposed, including basement membrane components, constituents of junctional complexes such as desmoplakin and enzymes such as 5'-nucleotidase. Additionally, a variety of cell surface molecules are thought to be differentially expressed, including PAL-E, VEGFR-3, podoplanin, and LYVE-1. Several of the lymphatic markers proposed in the literature require further characterization to demonstrate fully their lymphatic specificity and some have proven not to be reliable. The relative merits and drawbacks of each of the proposed markers is discussed.
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Biomarcadores , Endotelio Linfático , Animales , Endotelio Vascular , HumanosRESUMEN
It has generally been assumed that tumors do not induce lymphangiogenesis and only very recently animal models have been presented showing tumor-induced lymphangiogenesis. We have grown two types of rat tumor cells, 10AS pancreatic carcinoma and C6 glioma cells, on the chorioallantoic membrane (CAM) of chick and quail embryos. The suspended tumor cells rapidly formed solid tumors which invaded the CAM and were vascularized by CAM vessels. When grown on the CAM of quail embryos intratumoral endothelial cells could be specifically stained with the QH1 antibody. In C6 gliomas the vascular pattern was more regular than in 10AS carcinomas. The vessels often grew radially into the glioma and many of them were invested by smooth muscle alpha-actin-positive periendothelial cells. Lymphatics, which were identified by vascular endothelial growth factor receptor-3 (VEGFR-3) in situ hybridization were absent from C6 gliomas, although a weak expression of the lymphangiogenic growth factor, VEGF-C, could be detected in the C6 cells by Northern blot analysis. In contrast, 10AS cells, which expressed high levels of VEGF-C, induced ingrowth of lymphatics into the tumors, with BrdU-labeling rates of about 9% of lymphatic endothelial cells. Our studies demonstrate the heterogeneity of interactions of tumor cells with blood vessels and lymphatics and show that sufficient quantities and/or quality of lymphangiogenic growth factors are crucial for the induction of lymphatics in tumors.
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Corion/crecimiento & desarrollo , Coturnix/embriología , Sistema Linfático/embriología , Neovascularización Patológica , Animales , Bioensayo , Vasos Sanguíneos/fisiopatología , Vasos Sanguíneos/ultraestructura , Northern Blotting , Embrión de Pollo , Corion/irrigación sanguínea , Embrión no Mamífero , Factores de Crecimiento Endotelial/análisis , Sistema Linfático/ultraestructura , Microscopía Electrónica de Rastreo , Ratas , Proteínas Tirosina Quinasas Receptoras/análisis , Receptores de Factores de Crecimiento/análisis , Células Tumorales Cultivadas , Factor C de Crecimiento Endotelial Vascular , Receptor 3 de Factores de Crecimiento Endotelial VascularRESUMEN
VEGF-C and VEGF-D are lymphangiogenic factors that bind to and activate VEGFR-3, a fms-like tyrosine kinase receptor whose expression is limited almost exclusively to lymphatic endothelium in the adult. Processed forms of VEGF-C and VEGF-D can also activate VEGFR-2, a key player in the regulation of angiogenesis. There is increasing evidence to show that these receptor-ligand interactions play a pivotal role in a number of pathological situations. Inhibition of receptor activation by VEGF-C and VEGF-D could therefore be pharmaceutically useful. Furthermore, to understand the different roles of VEGF-C, VEGF-D, VEGFR-2 and VEGFR-3 in pathological situations it will be necessary to dissect the complex interactions of these ligands and their receptors. To facilitate such studies we cloned, sequenced and characterized the expression of rat VEGF-C and VEGF-D. We showed that Cys152-->Ser mutants of processed rat VEGF-C can activate VEGFR-3 but not VEGFR-2, while the corresponding mutation in rat VEGF-D inhibits its ability to activate both VEGFR-2 and VEGFR-3. We also synthesized and characterized indolinones that differentially block VEGF-C- and VEGF-D-induced VEGFR-3 kinase activity compared to that of VEGFR-2. These tools should be useful in analysing the different activities and roles of VEGF-C, VEGF-D and their ligands, and in blocking VEGFR-3-mediated lymphangiogenesis.
Asunto(s)
Factores de Crecimiento Endotelial/metabolismo , Inhibidores Enzimáticos/farmacología , Indoles/farmacología , Naftalenos/farmacología , Proteínas Tirosina Quinasas Receptoras/efectos de los fármacos , Receptores de Factores de Crecimiento/efectos de los fármacos , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Animales , Secuencia de Bases , Clonación Molecular , Drosophila/genética , Evaluación Preclínica de Medicamentos/métodos , Factores de Crecimiento Endotelial/genética , Inhibidores Enzimáticos/química , Indoles/química , Datos de Secuencia Molecular , Mutación , Naftalenos/química , Ratas , Proteínas Tirosina Quinasas Receptoras/metabolismo , Receptores de Factores de Crecimiento/metabolismo , Receptores de Factores de Crecimiento Endotelial Vascular , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homología de Secuencia de Aminoácido , Factor C de Crecimiento Endotelial Vascular , Factor D de Crecimiento Endotelial Vascular , Receptor 3 de Factores de Crecimiento Endotelial VascularRESUMEN
Antibodies against the histo-blood group B-like antigen M-N#1 efficiently block the growth in vivo of rat mammary carcinoma cells that bear the antigen (Sleeman et al., 1999, Oncogene 18, 4485--4494). To try to understand the function of the M-N#1 antigen, we investigated when and where the antigen is expressed during the normal function of the rat mammary gland. Expression was virtually only seen during mammary gland involution. Here, strong expression of the antigen was observed in mammary epithelial cells, beginning around 2 days postweaning and lasting throughout the involution process. Dexamethasone treatment of animals postlactation inhibited alveolar collapse and remodeling in the mammary gland but inhibited neither the apoptosis of mammary epithelial cells nor the expression of the M-N#1 antigen. We show that up-regulation of carbohydrate antigens is not a general phenomenon during mammary gland involution, and thus that M-N#1 antigen expression is specifically regulated. Up-regulation of alpha(1,2)fucosyltransferase A, an enzyme required for M-N#1 antigen synthesis, is at least partly responsible for regulated M-N#1 antigen expression postlactation. Most significantly, we observed that the M-N#1 antigen is virtually exclusively expressed on nonapoptosing epithelial cells in the involuting mammary gland. These data suggest that M-N#1 antigen expression might either provide a survival function and/or be expressed in epithelial cells that are destined to grow and remodel mammary duct structures.
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Sistema del Grupo Sanguíneo ABO , Células Epiteliales/metabolismo , Fucosiltransferasas/biosíntesis , Glándulas Mamarias Animales/crecimiento & desarrollo , Animales , Antígenos de Carbohidratos Asociados a Tumores/aislamiento & purificación , Femenino , Lactancia , Ratas , Regulación hacia Arriba , Destete , Galactósido 2-alfa-L-FucosiltransferasaRESUMEN
Proteolytic cleavage of the extracellular domain of CD44 from the surface of cells has been observed recently in different cell types. In cell culture supernatants of human melanoma cell lines a 70 kDa soluble CD44 protein (solCD44) was detected at concentrations of 250-300 ng/ml. Protease inhibitor studies revealed that serine proteases and metalloproteases are involved in the cleavage of CD44 from the surface of melanoma cells. To analyse a possible function of soluble CD44 a human malignant melanoma cell line was stably transfected with cDNAs encoding either wild type soluble CD44s or mutated forms with defective HA binding properties (CD44sR41A and CD44sR150A/R154A). Soluble CD44s almost completely inhibited hyaluronic acid binding by melanoma cells, whereas soluble CD44 mutated in the HA binding domain had no effect. When cultivated on hyaluronic acid, melanoma cell proliferation was induced by 30% for both the parental and the control transfected cells. This increase in proliferation was blocked completely in solCD44s-secreting transfectants, whereas solCD44sR41A and solCD44sR150A/R154A-secreting cells again showed hyaluronic acid-induced cell proliferation. These cell lines were subcutaneously injected into MF1 nu/nu mice to compare their growth as tumors in vivo. Compared to tumors derived from parental and control transfected cells, we observed a dramatic reduction of primary tumor growth with solCD44s expressing MM cells. Transfectants expressing solCD44s mutated in the HA binding domain in contrast developed fast-growing primary tumors. These results provide strong evidence that direct solCD44 interactions with hyaluronic acid interfere competitively with processes induced by hyaluronic acid binding to surface CD44. Autocrine, or drug-induced secretion of solCD44 by human melanoma cells may thus exert potent antitumoral effects in vivo.
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Receptores de Hialuranos/metabolismo , Ácido Hialurónico/metabolismo , Melanoma/metabolismo , Proteínas de Neoplasias/metabolismo , Animales , Sitios de Unión , Unión Competitiva , Adhesión Celular , División Celular , Medios de Cultivo , Glicopéptidos/farmacología , Humanos , Receptores de Hialuranos/química , Receptores de Hialuranos/genética , Melanoma Experimental/metabolismo , Melanoma Experimental/patología , Metaloendopeptidasas/antagonistas & inhibidores , Ratones , Ratones Desnudos , Proteínas de Neoplasias/química , Proteínas de Neoplasias/genética , Pepstatinas/farmacología , Fenantrolinas/farmacología , Inhibidores de Proteasas/farmacología , Unión Proteica/efectos de los fármacos , Estructura Terciaria de Proteína , Proteínas Recombinantes de Fusión/metabolismo , Eliminación de Secuencia , Sulfonas/farmacología , Transfección , Células Tumorales CultivadasRESUMEN
Using subtractive technology, we have generated metastasis-associated gene expression profiles for rat mammary and pancreatic adenocarcinomas. Several genes whose expression is thought to be related to tumor progression such as c-Met, urokinase-type plasminogen activator receptor, ezrin, HMG-1, oncomodulin, cathepsin, and caveolin were thereby isolated. Half of the metastasis-associated clones showed no significant homology to genes with known function. Notably, several of the metastasis-associated clones were also expressed in metastatic lines but not in nonmetastatic lines of other tumor models. Furthermore, in situ hybridization using selected clones documents the relevance of these results for human cancer because strong expression in tumor cells including metastases was detected in human colorectal cancer samples and, to a lesser extent, in mammary cancer samples. These data support the concept that tumors express a "metastatic program" of genes.
Asunto(s)
Perfilación de la Expresión Génica , Neoplasias/genética , Neoplasias/patología , Animales , Clonación Molecular , ADN Complementario/genética , ADN Complementario/metabolismo , ADN de Neoplasias/genética , ADN de Neoplasias/metabolismo , Regulación Neoplásica de la Expresión Génica , Humanos , Hibridación in Situ , Metástasis de la Neoplasia , Neoplasias/metabolismo , Neoplasias Experimentales/genética , Neoplasias Experimentales/metabolismo , Neoplasias Experimentales/patología , Fenotipo , Ratas , Regulación hacia ArribaRESUMEN
The metastatic spread of tumors is not a random process. Distinct patterns of metastasis can be discerned which vary from tumor type to tumor type. A common pattern, particularly for carcinomas, is that regional lymph nodes are often the first organs to develop metastases. This pattern of metastasis is central to the utility of the sentinel lymphonodectomy surgical technique. However, not all tumors and tumor types metastasize first to the regional lymph nodes. The mechanisms which determine whether regional lymph nodes or other sites first develop metastases remain poorly understood. In this article I review the anatomical, cellular and molecular factors which play a role in metastatic dissemination and determine patterns of metastasis. I then explore the importance of tumor heterogeneity and the selection of metastatically competent tumor cells during systemic dissemination, and suggest that some secondary sites are more readily colonised by metastasizing cells than others. Metastases at these sites act as bridgeheads, constituting a reservoir of tumor cells which, because they have already successfully metastasized, possess many of the properties required for metastasis to further sites. These tumor cells are therefore more likely than cells in the primary tumor to acquire all of the properties required for metastasis to less favourable secondary sites. To illustrate the bridgehead concept, I argue that features of the design and function of the lymphatic system make it highly amenable to the entry of metastasizing tumor cells and the formation of lymph node metastases, and suggest that lymph node metastases form a bridgehead for further metastatic spread.
Asunto(s)
Metástasis Linfática/fisiopatología , Metástasis de la Neoplasia/fisiopatología , Neoplasias/patología , Animales , Adhesión Celular , Movimiento Celular , Endopeptidasas/biosíntesis , Endopeptidasas/fisiología , Activación Enzimática , Inducción Enzimática , Regulación Neoplásica de la Expresión Génica , Humanos , Escisión del Ganglio Linfático , Sistema Linfático/patología , Modelos Biológicos , Mutación , Invasividad Neoplásica , Proteínas de Neoplasias/fisiología , Neoplasias/genética , Células Neoplásicas Circulantes , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patología , Neovascularización Patológica , Especificidad de Órganos , Ratas , Biopsia del Ganglio Linfático CentinelaRESUMEN
The neu/erbB2 protooncogene is overexpressed in numerous human cancers and is mutationally activated in N-ethyl-N-nitrosourea (ENU)-induced rodent tumors of the Schwann cell lineage. We investigated whether expression of activated neu in Schwann cells is sufficient to initiate their immortalization and transformation. Clones of embryonic dorsal root ganglia cells infected with a retrovirus bearing activated neu (NID cells) were selected based on their expression of Schwann cell-specific markers. Compared to embryonic Schwann cells infected with a virus encoding empty vector, we found that NID cells have altered shapes and disorganized cytoskeletons, grow in the absence of growth factors required for normal Schwann cell survival and proliferation, and can be repeatedly passaged. Furthermore, NID cells are invasive in an in vitro matrix invasion assay and form metastatic tumors when injected into syngeneic animals. The neu-induced growth and invasive phenotypes could be reversed by drugs that inhibit Ras and Src activity. Interestingly, later stage Schwann cells infected with activated neu failed to become immortalized. These findings indicate that constitutive activation of erbB2 is sufficient to initiate the immortalization and transformation of immature Schwann cells, and support the notion that Schwann cells have particular developmental stages during which they are susceptible to immortalizing and transforming events.
Asunto(s)
Transformación Celular Neoplásica/genética , Expresión Génica , Genes erbB-2 , Células de Schwann/patología , Animales , Axones , Adhesión Celular/genética , División Celular/genética , Humanos , Masculino , Metástasis de la Neoplasia , Fenotipo , Ratas , Retroviridae/genéticaRESUMEN
Using subtractive immunization to identify cell surface epitopes expressed in a metastasis-specific fashion on cells of the rat MT-W9 mammary carcinoma model, we generated a monoclonal antibody called M-N#1. This antibody binds specifically to metastasizing cells of the MT-W9 series and also to certain other metastasizing rat mammary carcinoma cell lines. We demonstrate that the M-N#1 antibody recognizes a fucosylated N-glycosyl sugar modification, and furthermore show that the epitope specificity of the M-N#1 antibody is for blood group antigen B subtypes 2, 3 and 4 with slight cross-reactivity with blood group antigen A subtype 2. The expression of these carbohydrate epitopes on MT-450 cells is functionally important, because the M-N#1 antibody efficiently inhibits MT-450 tumour growth in spontaneous metastasis assays. These results suggest that expression of the subtypes of blood group antigen B recognized by the M-N#1 antibody does not directly participate in the metastatic cascade but rather confers a growth or survival advantage on the tumour cells.
Asunto(s)
Sistema del Grupo Sanguíneo ABO/inmunología , Anticuerpos Monoclonales/farmacología , División Celular , Neoplasias Mamarias Experimentales/patología , Animales , Línea Celular , Femenino , Humanos , Neoplasias Mamarias Experimentales/inmunología , Metástasis de la Neoplasia , Ratas , Ratas Endogámicas WF , Células Tumorales CultivadasAsunto(s)
Adhesión Celular/fisiología , Transformación Celular Neoplásica , Proteínas de la Matriz Extracelular/fisiología , Receptores de Hialuranos/fisiología , Animales , División Celular , Proteínas de la Matriz Extracelular/genética , Humanos , Receptores de Hialuranos/genética , Sistemas de Lectura AbiertaRESUMEN
CD44 is important during myelopoiesis, although the contributions of variant CD44 proteins are unclear. We show here that in human long-term bone marrow culture antibodies recognizing a CD44 NH2-terminal epitope (mab 25-32) or a CD44v6 epitope (mab VFF18) inhibit myelopoiesis. However, mab 25-32 but not mab VFF18 affects myeloid colony formation. These data suggest that an early precursor cell compartment is the target for the 25-32 antibody, whereas the mab VFF18 targets later stages in myelopoiesis. Since the bulk of hemopoietic precursor cells are negative for the v6 epitope and only a minor subset of myeloid cells express the v6 epitope, we have used several human myeloid progenitor cell lines to unravel the function of different CD44 proteins. These cell lines produce variant CD44 proteins, predominantly a new variant CD44v4-v10, when stimulated towards myeloid differentiation. Features that can be acquired by the expression of CD44v4-v10 are an increased hyaluronate (HA) and a de novo chondroitin sulphate A (CS-A) binding. Although, the expression of CD44v4-v10 per se is necessary for HA and CS-A binding, the protein backbone seems to require appropriate glycosylation. HA binding results in CD44-mediated cellular self-aggregation and adhesion to the stromal cell line MS-5. In summary, our data suggest that different CD44 proteins are important for at least two different steps in myelopoiesis.