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Query: UMLS:C0178874 (tumor progression)
40,807 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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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PMID:New insights into the role of extracellular matrix during tumor onset and progression. 1212 71

Malignant tumors have the ability to invade normal tissue and to spread to distant sites giving rise to metastasis, which are major factors in the morbidity and mortality of colorectal cancer. Invasion and metastasis involve attachment of tumor cells to the basement membrane, degradation of the local connective tissue, and penetration and migration through proteolyzed stroma. The key enzymes responsible for ECM breakdown are matrix metalloproteinases (MMPs). To date, 26 MMP genes have been identified in humans, and many are implicated in cancer. ECM degradation by MMPs not only enhances tumor invasion, but also affects tumor cell behavior and leads to cancer progression. This review highlights recent developments with regard to the cellular and molecular mechanisms of MMPs that influence colorectal tumor cell growth, invasion, and metastasis.
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PMID:[Matrix metalloproteinases and colorectal cancer]. 1468 78

Although the overview above provides a partial molecular picture of the early stages of stepwise hepatocarcinogenesis. it should be emphasized that tumor and nontumor liver contain multiple changes, and that there is variability in their profile among different patients even within single studies. Variability in the number and types of genetic changes has also been observed geographically, and may be dependent upon the etiology of the tumor (viral, chemical or both). Interestingly, HBxAg inactivates tumor suppressors (such as p53 [by direct binding] and Rb [by stimulating its phosphorylation]) early in carcinogenesis that are mutated later during tumor progression. HBxAg also constitutively activates signal transduction pathways, such as those involving c-jun and ras, and activates oncogenes,such as c-nloc, that are otherwise activated by 3-catenin mutations. These findings suggest common molecular targets in hepatocarcinogenesis, despite different mechanisms of activation or inactivation. These observations need to be exploited in future drug discovery and in the development of new therapeutics. Heterogeneity in the mechanisms of tumor development, evidenced by the differences in the up- and down regulated genes reported in micro array analyses, as well as in the genetic loci that undergo mutation or LOH indifferent reports, has now been well documented. This suggests that there are multiple pathways to HCC, and that there is redundancy in the pathways that regulate cell growth and survival. These findings also reflect that,although hepatocarcinogenesis is multistep, the molecular changes that underpin histopathological changes in tumor development are likely to be different or only partially overlapping in individual tumors. Overall, the consequences of these changes suggest that the pathogenesis of HCC is accompanied by a progressive loss of differentiation, loss of normal cell adhesion, loss of the ECM, and constitutive activation of selected signal transduction pathways that promote cell growth and survival. Although mechanisms are important, attention also has to be paid to the target genes whose altered expression actually mediate the neoplastic phenotype. Other key avenues of work need to be explored. For example, it will be important to try to identify germline mutations in HBV-infected patients that are passed on to their children, resulting in the development of HCC in childhood. Clinical materials will also be important for the validation of new markers with diagnostic or prognostic potential. In this context, there is an urgent need to establish simple and low-cost tests based upon molecular changes that are hallmarks of HCC development. Identification of patients with early HCC will also significantly increase survival through its impact upon treatment. The discovery and validation of HCC markers may permit accurate staging of lesions, determine the proximity of such lesions to malignancy, and determine whether lesions with a particular genetic profile are still capable of remodeling through appropriate therapeutic intervention. The efficient reintroduction of the relevant tumor suppressors, or the inhibition of oncogene expression by siRNA, provide just some of the additional opportunities that will ultimately be useful in patient treatment. Together, these approaches will go far in reducing the very high morbidity and mortality associated with HCC.
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PMID:Early molecular and genetic determinants of primary liver malignancy. 1506 49

An inaugural conference in Tucson Arizona on May 6-9, 2004 brought together more than 70 clinical and basic scientists to discuss recent research advances in understanding and targeting the progression of the human prostate cancer. The informal meeting was unique in that it provided the opportunity for discussion and interaction between these different groups of scientists whose paths rarely cross. The goal of the meeting was to develop new and novel approaches in understanding the human prostate cancer in order to uncover therapeutic targets. Faculty from six different cancer centers were represented including Memorial Sloan-Kettering Cancer Center (New York, NY); Arizona Cancer Center (Tucson, AZ); Fred Hutchinson Cancer Center (Seattle, WA); Chao Family Comprehensive Cancer Center (Irvine, CA); the Sydney Kimmel Cancer Center (San Diego, CA); Jonsson Comprehensive Cancer Center, University of California (Los Angeles, CA); and University of Massachusetts Memorial Cancer Center (Worcester, MA). Several important concepts emerged from this meeting as a result of the basic and clinical science interface. These concepts include: (1) Human prostate cancer has unique biological features as compared to other human epithelial malignancies; (2) Tumor plasticity is evident early in prostate cancer progression as evidenced by alterations in the extracellular matrix; (3) New therapeutic strategies should include the co-targeting of the stroma and prostate cancer; (4) Cell-cell and cell-ECM adhesion switching are reversible phenotypes evident early in human prostate tumor progression; (5) The discovery of molecular signatures including genomic or proteomic patterns for the discrimination of indolent versus aggressive disease is a potentially powerful tool and requires multifactorial approaches for success; and (6) New biomarkers and innovative tissue specific imaging modalities for human prostate cancer are being developed that may aid in a more accurate assessment of prostate cancer in patients.
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PMID:Therapeutic targeting of prostate cancer. 1553 35

The interactions of transformed cells with the surrounding stromal cells are of importance for tumor progression and metastasis. The relevance of adipocyte-derived factors to breast cancer cell survival and growth is well established. However, it remains unknown which specific adipocyte-derived factors are most critical in this process. Collagen VI is abundantly expressed in adipocytes. Collagen(-/-) mice in the background of the mouse mammary tumor virus/polyoma virus middle T oncogene (MMTV-PyMT) mammary cancer model demonstrate dramatically reduced rates of early hyperplasia and primary tumor growth. Collagen VI promotes its growth-stimulatory and pro-survival effects in part by signaling through the NG2/chondroitin sulfate proteoglycan receptor expressed on the surface of malignant ductal epithelial cells to sequentially activate Akt and beta-catenin and stabilize cyclin D1. Levels of the carboxyterminal domain of collagen VIalpha3, a proteolytic product of the full-length molecule, are dramatically upregulated in murine and human breast cancer lesions. The same fragment exerts potent growth-stimulatory effects on MCF-7 cells in vitro. Therefore, adipocytes play a vital role in defining the ECM environment for normal and tumor-derived ductal epithelial cells and contribute significantly to tumor growth at early stages through secretion and processing of collagen VI.
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PMID:Adipocyte-derived collagen VI affects early mammary tumor progression in vivo, demonstrating a critical interaction in the tumor/stroma microenvironment. 1584 Dec 11

Dermatologists are faced daily with the need to optimize skin repair and excise cutaneous cancers. The extracellular matrix plays a pivotal role in cellular migration, proliferation, and gene regulation during wound healing and progression of melanoma, basal cell carcinoma, and squamous cell carcinoma. Within the last few years, a new class of ligand, the matrikine or matricryptin, has been characterized as subdomains of various ECM proteins capable of signaling to the cell through receptors, such as growth factor receptors. Two classes exist: the "natural" matrikines, which signal directly from the extracellular milieu and "cryptic" matrikines (matricryptins) that require proteolytic processing to reveal the ligand or to release the ligand from its ECM protein. Unlike traditional soluble growth factors, most matrikines possess low binding affinity to their receptors and are often presented in multiple valency that likely increase avidity to receptors. The presentation of these ligands within the ECM can result in unique outcomes. The EGF-like repeats of tenascin-C and laminin-5 signal to EGFR preferentially to upregulate migration during skin repair and tumor progression. Other matrikines in collagen, elastin, decorin, and laminin-1 can promote chemotaxis, mitogenesis, and metastasis in cancers, such as melanoma. Finally, the unique properties of matrikines have been utilized in cancer therapeutics and tissue engineering. Within the next few years, the nature and function of this emerging class of matrikine ligands will have an impact on dermatology, as these proteins are altered in wound repair and skin diseases.
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PMID:Matrikines and matricryptins: Implications for cutaneous cancers and skin repair. 1599 69

Cancer progression depends on an accumulation of metastasis supporting cell signaling molecules that target signal transduction pathways and ultimately gene expression. Osteopontin (OPN) is one such chemokine like metastasis gene which plays a key signaling event in regulating the oncogenic potential of various cancers by controlling cell motility, invasiveness and tumor growth. We have reported that OPN stimulates tumor growth and nuclear factor kappaB (NFkappaB)-mediated promatrix metalloproteinase-2 (pro-MMP-2) activation through IkappaBalpha/IKK (IkappaBalpha kinase) signaling pathway in melanoma cells. Urokinase type plasminogen activator (uPA), a widely acting serine protease degrades the ECM components and plays a pivotal role in cancer progression. However, the molecular mechanism by which upstream kinases regulate the OPN-induced NFkappaB activation and uPA secretion in human breast cancer cells is not well defined. Here we report that OPN induces the phosphatidylinositol 3'-kinase (PI 3'-kinase) activity and phosphorylation of Akt/PKB (protein kinase B) in highly invasive (MDA-MB-231) and low invasive (MCF-7) breast cancer cells. The OPN-induced Akt phosphorylation was inhibited when cells were transfected with dominant negative mutant of p85 domain of PI 3'-kinase (Deltap85) indicating that PI 3'-kinase is involved in Akt phosphorylation. OPN enhances the interaction between IkappaBalpha kinase (IKK) and phosphorylated Akt. OPN also induces NFkappaB activation through phosphorylation and degradation of IkappaBalpha by inducing the IKK activity. OPN also enhances uPA secretion, cell motility and ECM-invasion. Furthermore, cells transfected with Deltap85 or super-repressor form of IkappaBalpha suppressed the OPN-induced uPA secretion and cell motility. Pretreatment of cells with PI 3'-kinase inhibitors or NFkappaB inhibitory peptide (SN50) reduced the OPN-induced uPA secretion, cell motility and ECM-invasion. Taken together, OPN induces NFkappaB activity and uPA secretion by activating PI 3'-kinase/Akt/IKK-mediated signaling pathways and further demonstrates a functional molecular link between OPN induced PI 3'-kinase dependent Akt phosphorylation and NFkappaB-mediated uPA secretion, and all of these ultimately control the motility and invasiveness of breast cancer cells.
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PMID:Osteopontin: it's role in regulation of cell motility and nuclear factor kappa B-mediated urokinase type plasminogen activator expression. 1601 53

Anchorage-independent growth, anoikis resistance, and most steps of metastasis formation are integrin-mediated or -dependent processes, which are characteristics of malignant tumor cells. Acting as oncogenes or tumor suppressor genes, integrins may be involved in the oncogenic transformation of normal cells and their growth into a primary tumor node. During tumorigenesis, a switch of integrin expression can be observed, inasmuch as growth-promoting and growth-attenuating integrins are up- and down-regulated, respectively. ECM-ligand binding to an integrin initiates signals, which eradiating from the integrins are transmitted via different yet interconnecting pathways and elicit various cell functions, such as morphological changes, adhesion, migration and gene activation. Any of these functions takes part in the metastatic cascade of tumor progression, such as epithelial-to-mesenchymal transition of carcinoma cells, tumor cell contact with the basement membrane, invasion into neighboring tissues as well as production and activation of ECM-degrading MMPs. Besides their direct involvement in tumor progression as cell surface molecules on tumor cells, integrins in normal cells surrounding a tumor, e.g. endothelial cells, can also determine various cancer characteristics, such as tumor-induced neoangiogenesis and immune resistance. Hence, integrins are relevant pharmacological targets in tumor biology. Spurred by the recent success to generate pharmaceutical mimetics of RGD-dependent integrins and by the integrin's easy accessibility on the cell surface, the hope is rising that also RGD-independent integrins, such as the collagen- and laminin-binding integrins, can be pharmacologically manipulated to fight integrin-dependent functions of cancer cells, which are necessary and at least partially specific for their proliferation and progression.
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PMID:Integrins in cancer treatment. 1652 40

A dynamic, complex relationship exists between tumor cells and their microenvironment, which plays a pivotal role in cancer progression, yet remains poorly understood. Particularly perplexing is the finding that aggressive melanoma cells express genes associated with multiple cellular phenotypes, in addition to their ability to form vasculogenic-like networks in three-dimensional matrix--called vasculogenic mimicry, which is illustrative of tumor cell plasticity. This study addressed the unique epigenetic effect of the microenvironment of aggressive melanoma cells on the behavior of poorly aggressive melanoma cells exposed to it. The data show significant changes in the global gene expression of the cells exposed to 3-D matrices preconditioned by aggressive melanoma cells, including the acquisition of a vasculogenic cell phenotype, upregulation of ECM remodeling genes, and increased invasive ability--indicative of an epigenetic, microenvironment-induced reprogramming of poorly aggressive melanoma cells. However, this epigenetic effect was completely abrogated when a highly cross-linked collagen matrix was used, which could not be remodeled by the aggressive melanoma cells. These findings offer an unique perspective of the inductive properties associated with an aggressive melanoma microenvironment that might provide new insights into the epigenetic regulation of tumor cell plasticity and differentiation, as well as mechanisms that could be targeted for novel therapeutic strategies.
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PMID:The epigenetic reprogramming of poorly aggressive melanoma cells by a metastatic microenvironment. 1656 30

Matrix metalloproteinase-8 (MMP-8), also known as collagenase-2 or neutrophil collagenase, was long thought to be expressed solely by maturing neutrophils, and functionally restricted to ECM breakdown. Recent experiments, however, have revealed that this protease can be expressed by a wide variety of cell types and that it plays an important regulatory role in both acute and chronic inflammation. This review intends to give the reader an overview of the most interesting recent findings concerning the role of MMP-8 in inflammation and in cancer progression.
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PMID:Matrix metalloproteinase-8: cleavage can be decisive. 1682 Mar 17


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