101
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Li G, Fukunaga M, Herlyn M. Reversal of melanocytic malignancy by keratinocytes is an E-cadherin-mediated process overriding beta-catenin signaling. Exp Cell Res 2004; 297:142-51. [PMID: 15194432 DOI: 10.1016/j.yexcr.2004.03.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2003] [Revised: 02/02/2004] [Indexed: 01/01/2023]
Abstract
Loss of E-cadherin in melanoma cells frees them from keratinocytes-mediated proliferation and phenotypic control, which can be restored by forced E-cadherin expression. In this study, E-cadherin and its derivatives were introduced into metastatic melanoma line 1205Lu. E-cadherin and E-cadherin-alpha-catenin fusion protein were functional in mediating cell adhesion, downregulating MCAM(4) in coculture, and inhibiting proliferation regardless of beta-catenin expression levels and activation status. In contrast, cytoplasmic domain-deleted (E-cadDeltaCYT) derivative was not able to reverse malignancy. The results indicate that E-cadherin-mediated cell adhesion is required for keratinocyte-mediated control of melanocytic cells, which can override proliferative activity of beta-catenin.
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Affiliation(s)
- Gang Li
- The Wistar Institute, Philadelphia, PA 19104, USA
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102
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Affiliation(s)
- Rita Mulherkar
- Advanced Centre for Treatment, Tata Memorial Centre, Kharghar, Navi Mumbai, India.
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103
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Allinen M, Beroukhim R, Cai L, Brennan C, Lahti-Domenici J, Huang H, Porter D, Hu M, Chin L, Richardson A, Schnitt S, Sellers WR, Polyak K. Molecular characterization of the tumor microenvironment in breast cancer. Cancer Cell 2004; 6:17-32. [PMID: 15261139 DOI: 10.1016/j.ccr.2004.06.010] [Citation(s) in RCA: 977] [Impact Index Per Article: 48.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2003] [Revised: 03/16/2004] [Accepted: 05/18/2004] [Indexed: 02/06/2023]
Abstract
Here we describe the comprehensive gene expression profiles of each cell type composing normal breast tissue and in situ and invasive breast carcinomas using serial analysis of gene expression. Based on these data, we determined that extensive gene expression changes occur in all cell types during cancer progression and that a significant fraction of altered genes encode secreted proteins and receptors. Despite the dramatic gene expression changes in all cell types, genetic alterations were detected only in cancer epithelial cells. The CXCL14 and CXCL12 chemokines overexpressed in tumor myoepithelial cells and myofibroblasts, respectively, bind to receptors on epithelial cells and enhance their proliferation, migration, and invasion. Thus, chemokines may play a role in breast tumorigenesis by acting as paracrine factors.
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MESH Headings
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Breast/metabolism
- Breast/pathology
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Carcinoma in Situ/genetics
- Carcinoma in Situ/metabolism
- Carcinoma in Situ/pathology
- Carcinoma, Ductal, Breast/genetics
- Carcinoma, Ductal, Breast/metabolism
- Carcinoma, Ductal, Breast/pathology
- Cell Division
- Cell Movement
- Chemokine CXCL12
- Chemokines, CXC/genetics
- Chemokines, CXC/metabolism
- Disease Progression
- Epithelium/metabolism
- Epithelium/pathology
- Female
- Gene Expression Profiling
- Gene Expression Regulation, Neoplastic
- Gene Library
- Humans
- Muscle, Smooth/cytology
- Neoplasm Invasiveness/pathology
- Neoplasm Proteins/genetics
- Tumor Cells, Cultured
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Affiliation(s)
- Minna Allinen
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA
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104
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Schmidt-Hansen B, Klingelhöfer J, Grum-Schwensen B, Christensen A, Andresen S, Kruse C, Hansen T, Ambartsumian N, Lukanidin E, Grigorian M. Functional significance of metastasis-inducing S100A4(Mts1) in tumor-stroma interplay. J Biol Chem 2004; 279:24498-504. [PMID: 15047714 DOI: 10.1074/jbc.m400441200] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Causal implication of S100A4 in inducing metastases was convincingly shown previously. However, the mechanisms that associate S100A4 with tumor progression are not well understood. S100A4 protein, as a typical member of the S100 family, exhibits dual, intracellular and extracellular, functions. This work is focused on the extracellular function of S100A4, in particular its involvement in tumor-stroma interplay in VMR (mouse adenocarcinoma cell line) tumor cells, which exhibit stroma-dependent metastatic phenotype. We demonstrated the reciprocal influence of tumor and stroma cells where tumor cells stimulate S100A4 secretion from fibroblasts in culture. In turn, extracellular S100A4 modifies the cytoskeleton and focal adhesions and triggers several other events in tumor cells. We found stabilization of the tumor suppressor protein p53 and modulation of its function. In particular, extracellular S100A4 down-regulates the pro-apoptotic bax and the angiogenesis inhibitor thrombospondin-1 genes. For the first time, we demonstrate here that the S100A4 protein added to the extracellular space strongly stimulates proteolytic activity of VMR cells. This activity most probably is associated with matrix metalloproteinases and, in particular, with matrix metalloproteinase-13. Finally, the application of the recombinant S100A4 protein confers stroma-independent metastatic phenotype on VMR tumor cells. In conclusion, our results indicate that metastasis-inducing S100A4 protein plays a pivotal role in the tumor-stroma environment. S100A4 released either by tumor or stroma cells triggers pro-metastatic cascades in tumor cells.
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Affiliation(s)
- Birgitte Schmidt-Hansen
- Department of Molecular Cancer Biology, Institute of Cancer Biology, Danish Cancer Society, Strandboulevarden 49, DK-2100 Copenhagen, Denmark
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105
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Abstract
Lymphatic mapping and sentinel lymphadenectomy provide a minimally invasive means of directly determining the status of the regional lymph nodes in all patients who have a primary melanoma >1 mm thick but no clinical evidence of nodal involvement. Since the histological status of the sentinel node (SN) has been shown to be the most important prognostic factor in primary melanoma patients, the World Health Organization has recently recommended that sentinel lymphadenectomy should become the new standard of care for primary melanoma patients. This paper reviews the literature with regards to developments in and the current status of SN evaluation. Developments in the histopathological versus molecular detection of melanoma nodal metastases are reviewed, with specific emphasis on the strengths, limitations and clinical significance of these techniques. Molecular evaluation of the SN offers several advantages over standard histopathological analysis. These include an improved sensitivity, the cost-effective use of multiple markers for the improvement of detection rate and prognosis, as well as being less labour-intensive and costly. Moreover, molecular analysis has the potential to allow estimation of tumour burden. We review the potential causes of technical false-negative and false-positive reverse transcription-polymerase chain reaction (RT-PCR) results and how these could be eliminated by a systematic approach consisting of (i) careful and systematic assay design, which would include efficient tissue homogenization, choice of reagents and molecular markers, primer design and the use of one-stage versus two-stage PCR; (ii) careful optimization of the RT-PCR parameters (in particular the PCR cycle number) through the use of appropriate control tissues; and (iii) aiming for high assay reproducibility and lastly by applying the necessary positive and negative controls with each batch of samples. We also review the significant improvement in patient prognosis and management that has been made possible by the development of sentinel lymphadenectomy and histopathological evaluation of the SN, and compare the clinical (predictive) value of histopathological analysis with that of RT-PCR. Although RT-PCR is able to detect additional, clinically significant SN metastases that are missed by routine histopathology, its current limitation is that it overestimates the number of patients who have clinically significant melanoma metastases. Therefore, we suggest and discuss appropriate steps that need to be taken in order to minimize these false-positives and make this molecular tool more acceptable for routine clinical use.
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106
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Affiliation(s)
- Hiroaki Kitano
- Sony Computer Science Laboratories, Inc., 3-14-13 Higashi-Gotanda, Shinagawa, Tokyo 141-0022, Japan.
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107
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Hornebeck W, Maquart FX. Proteolyzed matrix as a template for the regulation of tumor progression. Biomed Pharmacother 2003; 57:223-30. [PMID: 12888258 DOI: 10.1016/s0753-3322(03)00049-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Pericellular proteolysis plays a pivotal function in cell invasion, a hallmark of tumor growth and metastasis. The minidegradome constituted of two matrix metalloproteinases (MMP), i.e. MMP-2 and MT1-MMP, associated with tissue inhibitor of metalloprotease-2 (TIMP-2) and integrin (alpha(v)beta(3)) or CD(44), is mainly involved in such invasive program. It catalyzes matrix degradation but, alternatively, proteolytic exposure of matricryptic sites or matrikines liberation by those enzymes regulates either positively or negatively tumor cell migration. That applies to types I and IV collagens, elastin, laminin 5, as described here, but such phenomenon might be extended to other matrix macromolecules. The development of tumors from epithelium origin is related to aging. Senescent fibroblasts are characterized by increased expression of MMPs, (particularly collagenase-1 (MMP-1) and stromelysin-1 (MMP-3)) and deposited matrix by those aged cells was shown to favor cancer cell growth. Thus, compositional variation of matrix-surrounding tumor cells, with formation of matricryptic sites and matrikines, can be considered as one main epigenetic factor contributing to tumor progression. A matrix-directed pharmacological approach in cancer is now emerging.
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Affiliation(s)
- William Hornebeck
- Faculté de Médecine, Centre National de la Recherche Scientifique (CNRS, FRE 2534), IFR 53 Biomolécules, Université de Reims, Champagne Ardenne, 51, rue Cognacq Jay, 51095 Reims cedex, France.
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108
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Abstract
The majority of pituitary adenomas are trophically stable and change relatively little in size over many years. A comparatively small proportion behave more aggressively and come to clinical attention through inappropriate hormone secretion or adverse effects on surrounding structures. True malignant behaviour with metastatic spread is very atypical. Pituitary adenomas that come to surgery are predominantly monoclonal in origin and roughly half are aneuploid, indicating either ongoing genetic instability or transition through a period of genetic instability at some time during their development. Few are associated with the classical mechanisms of tumour formation but it is generally believed that the majority harbour quantitative if not qualitative differences in molecular composition compared to the normal pituitary. Despite their prevalence and the ready availability of biopsy material, at the present time, the precise molecular pathogenesis of the majority of pituitary adenomas remains unclear. This review summarizes current thinking.
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Affiliation(s)
- Andy Levy
- University Research Centre for Neuroendocrinology, Bristol University, Jenner Yard, Bristol BS2 8HW, UK.
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109
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Clarijs R, Ruiter DJ, De Waal RMW. Pathophysiological implications of stroma pattern formation in uveal melanoma. J Cell Physiol 2003; 194:267-71. [PMID: 12548547 DOI: 10.1002/jcp.10214] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Clinical outcome of cancer patients is mainly determined by the rate of metastasis and, also by primary tumor growth. Formation of extracellular matrix and interactions of neoplastic and non-neoplastic (host) cells in solid tumors have been shown to be essential for these processes. One result of such interactions is the outgrowth of new blood vessels from existing ones, angiogenesis, to provide the tumor tissue with oxygen and nutrients. It is assumed that the neovascular bed also facilitates the escape of metastatic cells from the primary lesions. In addition, recent reports suggested the existence of blood-conducting channels lined by melanoma cells (so-called "vascular channels") accompanied by depositions of extracellular matrix patterns in cutaneous and uveal melanoma. Since the presence of these matrix structures has been negatively associated with prognosis, we hypothesize that they play a role in melanoma outgrowth or metastasis. In this review, we will discuss the morphological and functional properties of the extracellular matrix patterns in that may underlie these clinical phenomena.
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Affiliation(s)
- Ruud Clarijs
- Department of Pathology, University Medical Center Nijmegen, the Netherlands.
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110
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Brekken RA, Puolakkainen P, Graves DC, Workman G, Lubkin SR, Sage EH. Enhanced growth of tumors in SPARC null mice is associated with changes in the ECM. J Clin Invest 2003; 111:487-95. [PMID: 12588887 PMCID: PMC151926 DOI: 10.1172/jci16804] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
SPARC, a 32-kDa glycoprotein, participates in the regulation of morphogenesis and cellular differentiation through its modulation of cell-matrix interactions. Major functions defined for SPARC in vitro are de-adhesion and antiproliferation. In vivo, SPARC is restricted in its expression to remodeling tissues, including pathologies such as cancer. However, the function of endogenous SPARC in tumor growth and progression is not known. Here, we report that implanted tumors grew more rapidly in mice lacking SPARC. We observed that tumors grown in SPARC null mice showed alterations in the production and organization of ECM components and a decrease in the infiltration of macrophages. However, there was no change in the levels of angiogenic growth factors in comparison to tumors grown in wild-type mice, although there was a statistically significant difference in total vascular area. Whereas SPARC did inhibit the growth of tumor cells in vitro, it did not have a demonstrable effect on the proliferation or apoptosis of tumor cells in vivo. These data indicate that host-derived SPARC is important for the appropriate organization of the ECM in response to implanted tumors and highlight the importance of the ECM in regulating tumor growth.
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Affiliation(s)
- Rolf A Brekken
- Department of Vascular Biology, The Hope Heart Institute, Seattle, Washington 98104-2046, USA
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111
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Abstract
The microenvironment or stroma immediately surrounding tumor cells consists of a three-dimensional extracellular matrix (ECM) and stromal cells such as fibroblasts and inflammatory cells. The matrix metalloproteinases (MMPs) constitute a family of over 24 members, which collectively are capable of degrading virtually the entire ECM. Strict regulation of MMP expression is critical in order to maintain proper ECM homeostasis, but in disease states such as cancer there is often a high level of MMP activity at the tumor-stroma interface. Several studies have documented the importance of MMP-mediated ECM destruction in the successful dissemination of several tumor types, but it has become increasingly clear that they are also involved in earlier stages of tumorigenesis. MMPs are implicated in a wide variety of roles that can assist tumor initiation, growth, migration, angiogenesis, the selection of apoptosis-resistant subpopulations, and in invasion and metastasis. Interestingly, the factors responsible for many of these effects are derived from the cell surfaces of the tumor or stromal cells or are embedded in the ECM. Therefore, the MMPs can no longer be thought of solely as ECM destructionists, but as part of an elegant communication system through which the tumor interacts with the stroma.
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Affiliation(s)
- Conor C Lynch
- Department of Cancer Biology, Venderbilt University, Nashville, TN 37232-6840, USA.
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112
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van Kempen LCL, Rhee JS, Dehne K, Lee J, Edwards DR, Coussens LM. Epithelial carcinogenesis: dynamic interplay between neoplastic cells and their microenvironment. Differentiation 2002; 70:610-23. [PMID: 12492502 DOI: 10.1046/j.1432-0436.2002.700914.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Matrix metalloproteinases (MMPs) have long been thought of as critical factors regulating matrix degradation associated with cell invasion into ectopic tissue compartments during primary tumor growth and metastasis. One member of the MMP family historically linked to these invasive processes is MMP-9/gelatinase B. By studying a transgenic mouse model of de novo epithelial carcinogenesis, new roles for MMP-9 have emerged that broaden the view of its functional contribution to malignant progression. The combined implication of these studies suggest that MMP-9 functionally contributes to cancer development; however, its major regulatory role may be in its ability to activate poorly diffusible and/or matrix-sequestered growth factors that regulate epithelial and/or endothelial cell growth as opposed to regulating cellular invasion across basement membranes.
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Affiliation(s)
- Léon C L van Kempen
- Cancer Research Institute, University of California, San Francisco, CA 94115, USA.
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113
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Pupa SM, Ménard S, Forti S, Tagliabue E. New insights into the role of extracellular matrix during tumor onset and progression. J Cell Physiol 2002; 192:259-67. [PMID: 12124771 DOI: 10.1002/jcp.10142] [Citation(s) in RCA: 210] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Recently, a view of the tumor as a functional tissue interconnected with the microenvironment has recently been described. For many years, the stroma has been studied in the context of the malignant lesion, and only rarely has its role been considered before carcinogenic lesions appear. Recent studies have provided evidence that stromal cells and their products can cause the transformation of adjacent cells through transient signaling that leads to the disruption of homeostatic regulation, including control of tissue architecture, adhesion, cell death, and proliferation. It is now well established that tumor progression requires a continually evolving network of interactions between neoplastic cells and extracellular matrix. A relevant step of this process is the remodeling of microenvironment which surrounds tumors leading to the release of ECM-associated growth factors which can then stimulate tumor and/or endothelial cells. Finally, tumor cells reorganizing the extracellular matrix to facilitate communications and escape the homeostatic control exerted by the microenvironment modify response to cytotoxic treatments.
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Affiliation(s)
- Serenella M Pupa
- Molecular Targeting Unit, Department of Experimental Oncology, Istituto Nazionale Tumori, Milan, Italy
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114
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Abstract
Interleukin-1 (IL-1) represents a family of two agonistic proteins, IL-1alpha and IL-1beta, that are pleiotropic and affect hemopoiesis, inflammation, and immunity. In the context of the producing cell, IL-1beta is solely active in its secreted form, whereas IL-1alpha is active as an intracellular precursor, as a membrane-associated cytokine and to a lesser extent as a secreted molecule. IL-1 is abundant at tumor sites, where it may not only affect the growth and invasiveness of malignant cells, but where it may also induce antitumor immunity. Here we review the effects of microenvironmental and tumor cell-associated IL-1 on malignant processes, in experimental tumor models and in cancer patients.
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Affiliation(s)
- Ron N Apte
- Department of Microbiology and Immunology, Faculty of Health Sciences and The Cancer Research Center, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
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115
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Nielsen HL, Rønnov-Jessen L, Villadsen R, Petersen OW. Identification of EPSTI1, a novel gene induced by epithelial-stromal interaction in human breast cancer. Genomics 2002; 79:703-10. [PMID: 11991720 DOI: 10.1006/geno.2002.6755] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
During growth, invasion, and metastasis, tumor cells interact extensively with the surrounding stroma. To identify genes that are upregulated during this process, we compared mRNA pooled from tumor cells and fibroblasts cultured separately to mRNA from cells in coculture. Using differential display (DD), a transcript representing a novel gene, designated epithelial-stromal interaction 1 (breast) (EPSTI1), was identified. EPSTI1 showed no homology to any known gene, but matched a cluster of expressed-sequence tags (ESTs). The full-length cDNA of 1508 bp was generated by 5'-RACE, included an open reading frame (ORF) encoding a putative 307-amino-acid protein, and mapped to chromosome 13q13.3. EPSTI1 was highly upregulated in invasive breast carcinomas compared with normal breast. In a tissue mRNA panel the most prominent expression of EPSTI1 was found in placenta. Thus, EPSTI1 is a novel human gene expressed in tissues characterized by extensive epithelial-stromal interaction, and expression of this gene may be a crucial event in invasion and metastasis of cancer.
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Affiliation(s)
- Helga Lind Nielsen
- Structural Cell Biology Unit, Department of Medical Anatomy A, the Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
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116
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Chang C, Werb Z. The many faces of metalloproteases: cell growth, invasion, angiogenesis and metastasis. Trends Cell Biol 2002. [PMID: 11684441 DOI: 10.1016/s0962-8924(01)82222-4] [Citation(s) in RCA: 219] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Metalloproteases are important in many aspects of biology, ranging from cell proliferation, differentiation and remodeling of the extracellular matrix (ECM) to vascularization and cell migration. These events occur several times during organogenesis in both normal development and during tumor progression. Mechanisms of metalloprotease action underlying these events include the proteolytic cleavage of growth factors so that they can become available to cells not in direct physical contact, degradation of the ECM so that founder cells can move across tissues into nearby stroma, and regulated receptor cleavage to terminate migratory signaling. Most of these processes require a delicate balance between the functions of matrix metalloproteases (MMPs) or metalloprotease-disintegrins (ADAMs) and natural tissue inhibitors of metalloproteases (TIMPs). In this review, we discuss recent progress in identifying an essential role for metalloproteases in axon outgrowth, as an example of a focal invasive event. We also discuss the evolving concept of how MMPs might regulate stem cell fate during tumor development.
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Affiliation(s)
- C Chang
- Department of Anatomy, Box 0452, University of California San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143-0452, USA
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117
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Abstract
Matrix metalloproteinases are enzymes that regulate tissue behavior by interactions with extracellular matrix proteins. RECK, a membrane-anchored inhibitor of MMPs was recently characterized for its role in development, tissue homeostasis, and for tumor angiogenesis.
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Affiliation(s)
- Valerie M Weaver
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, 3340 Smith Walk, Philadelphia, PA 19104, USA
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118
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Radisky D, Muschler J, Bissell MJ. Order and disorder: the role of extracellular matrix in epithelial cancer. Cancer Invest 2002; 20:139-53. [PMID: 11852996 PMCID: PMC2933209 DOI: 10.1081/cnv-120000374] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Derek Radisky
- Life Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 83-101, Berkeley, CA 94720
| | - John Muschler
- Life Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 83-101, Berkeley, CA 94720
| | - Mina J. Bissell
- Life Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 83-101, Berkeley, CA 94720
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119
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Abstract
Breast carcinoma is one of the most common neoplasms in women and is a leading cause of cancer related deaths worldwide. In recent years improved diagnostic tools have made it possible to detect breast cancers at early, even pre-invasive stages leading to a significant decrease in breast cancer mortality rates over the past decades. The increased number of patients diagnosed with pre-invasive breast tumors opened up new avenues in research and new dilemmas in clinical practice, since our understanding of the pathophysiology of such lesions is just beginning to emerge. Part of the delay and difficulty with analyzing pre-invasive tumors including ductal carcinoma in situ has been due to the lack of appropriate techniques suitable for studies of small, frequently microscopic size tumors. Recently developed technologies such as DNA microarrays and SAGE (serial analysis of gene expression) have made it possible to obtain comprehensive gene expression profiles of breast carcinomas of all stages. The application of these genomics approaches in combination with the complete sequence of the human genome and extensive molecular epidemiological studies is likely to further our understanding of the molecular basis of mammary tumorigenesis and will identify targets for risk prediction, cancer prevention and treatment.
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Affiliation(s)
- K Polyak
- Dana-Farber Cancer Institute and Harvard Medical School, 44 Binney St., Boston, MA 02115, USA.
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120
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Abstract
Metalloproteases are important in many aspects of biology, ranging from cell proliferation, differentiation and remodeling of the extracellular matrix (ECM) to vascularization and cell migration. These events occur several times during organogenesis in both normal development and during tumor progression. Mechanisms of metalloprotease action underlying these events include the proteolytic cleavage of growth factors so that they can become available to cells not in direct physical contact, degradation of the ECM so that founder cells can move across tissues into nearby stroma, and regulated receptor cleavage to terminate migratory signaling. Most of these processes require a delicate balance between the functions of matrix metalloproteases (MMPs) or metalloprotease-disintegrins (ADAMs) and natural tissue inhibitors of metalloproteases (TIMPs). In this review, we discuss recent progress in identifying an essential role for metalloproteases in axon outgrowth, as an example of a focal invasive event. We also discuss the evolving concept of how MMPs might regulate stem cell fate during tumor development.
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