Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0027651 (tumor)
685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Primary tumors of the central nervous system (CNS) very rarely metastasize to other parts of the body, both in animals and in man, irrespective of survival time. The only exception to this rule is observed in meningiomas in man with a metastasis incidence of 18.7%. Experimental studies have provided strong evidence for an important modulating role of the extracellular matrix upon the invasion capacity of tumors. Malignant progression of tumors depends upon accumulation of somatic mutations which impart a selective advantage for invasion into the surrounding connective stroma. Such mutations seem to result from an active confrontation and interaction between tumor cells and components of the stroma. As the parenchyma of the CNS is largely free of connective tissue no such selection interplay occurs in genuine CNS tumors, in contrast to tumors of the other parts of the body with an abundance of connective tissue surrounding them. This explains the rarity of extracranial metastases of CNS tumors. In contrast, other tumors of the body metastasize more frequently into the CNS. Obviously, this potency is correlated with the frequency of mutations at the CD44 gene locus.
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PMID:[Pathobiologic aspects of the limited extracranial metastasis capability of tumors of the central nervous system]. 754 Mar 90

1. CD44 is an adhesion molecule expressed by B and T lymphocytes that mediates cell attachment to extracellular matrix components and specific cell surface ligands. In normal process of T-cell development, CD44 can be implicated in homing of bone marrow-derived T-cell precursors into the thymus. In hematopoietic malignancies, CD44 and other adhesion molecules can mediate the behavior of neoplastic cells such as metastatic migration. In the leukemic process, CD44 expression is correlated with increased numbers of circulating blasts and it is present at other sites such as the central nervous system. 2. In the present study, CD44 was investigated in lymphoblasts from 30 patients with T-cell lymphoblastic leukemia (T-ALL) and in peripheral lymphocytes from 10 healthy individuals. CD44 expression was detected in 23 (77%) of T-ALL cases studied and was correlated with clinical features such as mediastinal mass, adenomegaly, and infiltration of the central nervous system and other organs. Interestingly, CD44 expression in patients with tumor infiltration was higher than in patients with no tumor infiltration. 3. These data suggest that CD44 may be regarded as an additional marker for tumor expansion in T-cell leukemias.
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PMID:CD44 expression in T-cell lymphoblastic leukemia. 754 Apr 75

CD44 is a polymorphic family of immunologically related integral membrane glycoproteins associated with cell matrix adhesion, lymphocyte activation and targeting, and tumor growth and metastasis. We studied CD44 expression in 114 formalin-fixed paraffin-embedded thyroid tumors using the A3D8 anti-human CD44 monoclonal antibody. Sixty-five of 67 papillary carcinomas (97%) strongly expressed CD44 with an intense plasma membrane pattern. Thirty-seven of these cases originated from Albany, New York, and 30 cases from Russia. Immunoreactivity was also observed in 9 of 16 follicular adenomas (56%); 4 of 8 Hurthle cell neoplasms (50%); 5 of 15 medullary carcinomas (33%); and 3 of 8 follicular carcinomas (38%). These results show that among thyroid neoplasms, papillary carcinomas preferentially display the CD44 antigen (P < or = 0.001). Nonneoplastic follicular epithelium exhibited a low to moderate level of staining. To further characterize the CD44 isoform, we tested a subset of cases with the 2F10 anti-human CD44 variant 6 monoclonal antibody, which recognizes a CD44 variant exon (CD44v6) implicated in tumor metastasis. Eleven of 11 papillary carcinomas tested were 2F10 positive, and 1 of the follicular carcinomas was positive. These results suggest the hypothesis that deregulated CD44v6 expression on the plasma membrane of papillary carcinoma cells contributes to the ability of those cells to metastasize to regional lymph nodes and then to remain dormant for years. Our results suggest that human papillary thyroid cancer will be an interesting model in which to further study the role of CD44 isoforms, particularly those containing CD44v6, in tumor metastasis and lymphatic invasion.
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PMID:Preferential expression of the cell adhesion molecule CD44 in papillary thyroid carcinoma. 754 70

Antibodies to CD44 have been used to inhibit a variety of processes which include lymphohemopoiesis, lymphocyte migration, and tumor metastasis. Some, but not all, CD44-mediated functions derive from its ability to serve as a receptor for hyaluronan (HA). However, sites on CD44 that interact with either ligands or antibodies are poorly understood. Interspecies rat/mouse CD44 chimeras were used to analyze the specificity of 25 mAbs and to determine that they recognize at least seven epitopes. Amino acid substitutions that resulted in loss of antibody recognition were all located in the region of homology to other cartilage link family proteins. While at least five epitopes were eliminated by single amino acid replacements, multiple residues had to be changed to destroy binding by other antibodies. One antibody was sensitive to changes in any of three separate parts of the molecule and some antibodies to distinct epitopes cross-blocked each other. Certain antibodies had the ability to increase HA binding by lymphocytes but this did not correlate absolutely with antibody specificity and was only partially attributable to CD44 cross-linking. Antibodies that consistently blocked HA recognition were all sensitive to amino acid changes within a short stretch of CD44. Such blocking antibodies interacted with CD44 more strongly than ligand in competition experiments. One large group of antibodies blocked ligand binding, but only with a particular cell line. This detailed analysis adds to our understanding of functional domains within CD44 and requirements for antibodies to influence recognition of one ligand.
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PMID:Monoclonal antibodies to CD44 and their influence on hyaluronan recognition. 754 51

CD44 is a polymorphic cell surface glycoprotein, currently proposed to be the principal cell surface receptor for hyaluronan. However, different isoforms of CD44, expressed in human lymphoid tumor cells, appear to have distinct effects on the ability of the cells to attach to hyaluronan-coated surfaces and on their capacity to form tumors in vivo. In the present study, we address the mechanisms that may regulate CD44 isoform-dependent adhesion to hyaluronan. We use a human Burkitt lymphoma, stably transfected with six different alternatively spliced human CD44 isoforms, to determine their potential hyaluronan binding and tumor growth promoting roles. We show that transfectants expressing CD44 splice variants that contain variable exons 6-10, 7-10 and 8-10 adhere to hyaluronan-coated surfaces weakly and that corresponding tumor formation in vivo is delayed with respect to CD44-negative parental cell-derived tumors. Abundant shedding of these three isoforms may play a significant role in determining the rate of tumor development. Transfectants expressing variable exon 3, on the other hand, fail to display CD44-mediated adhesion to hyaluronan, but form bone marrow tumors rapidly following intravenous injection. These observations suggest that different mechanisms regulate CD44-mediated adhesion and tumor growth, and provide evidence that expression of exon v3 may confer novel ligand-binding properties.
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PMID:Regulation of growth and dissemination of a human lymphoma by CD44 splice variants. 754 58

Over the last few years, it has become clear that cell adhesion receptors function in signal transduction processes leading to the regulation of cell growth and differentiation. Signal transduction by both integrins and CAMs has been shown to involve activation of tyrosine kinases, while CAM signaling in neural cells involves G proteins as well. In the case of integrins, some of the downstream signaling events intersect with the Ras pathway, particularly the activation of MAP kinases. In fibroblasts, integrin mediated anchorage to the substratum regulates cell cycle traverse, while in epithelial cells, loss of anchorage can trigger programmed cell death. In many cell types, but particularly monocytic cells, integrin ligation has a profound impact on gene expression. Preliminary evidence also implicates CAMs and selectins in gene regulation. A consistent theme in signal transduction mediated by adhesion receptors concerns the role of the cytoskeleton. Integrin mediated signaling processes are interrupted by cytoskeletal disassembly. Identification of the APC and neurofibromatosis type 2 tumor suppressors suggest that cytoskeletal complexes also play a key role in signaling by cadherins and CD44, respectively. Thus, signaling by cell adhesion receptors may involve aspects that impinge on previously known signaling pathways including the RTK/Ras pathway and serpentine receptor/G protein pathways. However, novel aspects of signal transduction involving cytoskeletal assemblies may also be critical.
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PMID:Signal transduction by cell adhesion receptors. 754 26

In order to evaluate putative changes of major adhesion molecule expression on plasma cells (PCs) associated with malignant transformation, tumor spreading, and immortalization, we have quantified and compared the expression of CD56, CD44, CD11a, CD49e, and CD45 RO/RA on normal PCs, malignant PCs from multiple myeloma patients in chronic phase, in accelerated phase with or without extramedullary progression, and from human myeloma cell lines. Plasma cell phenotype was defined with the use of two-color immunofluorescence in combination with B-B4 or anti-CD38 antibodies. We found that all the adhesion antigens were expressed on normal PCs. Malignancy was characterized by an overexpression of CD56, whereas extramedullary spreading was associated with a dramatic down expression of CD56. Although CD44 remained unchanged, the subpopulation of PCs expressing CD11a, CD49e, and CD45RA/RO were significantly reduced during malignancy, and each of these negative subpopulations increased during disease acceleration. We demonstrated that CD11a and CD49e expression were correlated and defined the same subpopulation of PCs. The phenotype of HMCLs was similar to the expression profile of patients in accelerated phase with extramedullary spreading. In conclusion, we show that significant changes of PC phenotype were associated with malignancy, were correlated with the disease evolution, and could be of diagnostic and prognostic value in individuals with monoclonal gammopathy and patients with multiple myeloma.
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PMID:Adhesion molecules on human myeloma cells: significant changes in expression related to malignancy, tumor spreading, and immortalization. 754 19

Autolymphocyte therapy (ALT) is adoptive cellular therapy of neoplastic disease based upon ex vivo activation of lymphocytes by either the supernatant derived from a previously prepared one-way mixed lymphocyte culture (MLC) or using low doses of the mitogenic monoclonal antibody OKT3 and a mixture of previously prepared cytokines (T3CS). We have previously demonstrated that nonspecific ex vivo activation of splenocytes from murine tumor-bearing hosts (TBH) using an MLC-supernatant or T3CS without the use of tumor antigen results in the expansion of the CD44+ (memory) T-cell subset. These CD44+ T-cells are the principal mediators of anti-tumor specificity in the ALT-cell population in advanced metastatic murine tumors and are able to protect against tumor challenge in healthy syngeneic mice (HSM). To determine if ALT is effective in an adjuvant setting, C57BL/6J splenocytes from HSM and TBH with B16 melanoma or Lewis lung (3LL) carcinoma were activated ex vivo using T3CS. Mice were implanted with either B16 melanoma or 3LL carcinoma and then underwent surgical excision of tumor. Tumor-excised mice (TEM) then received small numbers (10(6)) of ALT-cells derived from 3LL-TBH or B16-TBH splenocytes, HSM-derived ALT-cells, fresh splenocytes derived from 3LL-TBH or B16-TBH, or CD44-depleted ALT-cells. Significant anti-tumor activity as shown by prolonged survival (Day 100), cure of disease, and rejection of a local and systemic tumor rechallenge was demonstrated in 3LL-TEM that received B16-derived ALT-cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Autolymphocyte therapy. III. Effective adjuvant adoptive cellular therapy with in vivo anti-tumor specificity against murine melanoma and carcinoma using ex-vivo-activated memory T-lymphocytes. 960 13

We investigated the production of hyaluronan and the presence of hyaluronan receptors in a panel of human lung carcinoma cell lines, consisting of small cell carcinomas (SCLC) and non-small cell carcinomas (non-SCLC). These transformed cell lines produced only minute amounts of hyaluronan, whereas normal lung fibroblasts synthesized high amounts. CD44 molecules (an integral membrane glycoprotein suggested previously to function as a hyaluronan receptor) were differentially expressed on non-SCLC cell lines but essentially not on the SCLC cell lines. In contrast, RHAMM molecules (receptor for hyaluronan-mediated motility) were preferentially expressed on SCLC cells. Although all the lung tumor cell lines expressed various amounts of CD44 and RHAMM, only the SCLC line U-1752 could bind [3H]hyaluronan. The binding sites were saturated with about 19,700 hyaluronan molecules (Mr 1.4 x 10(6)) bound per cell with a Kd of 0.16 x 10(-9) M. CD44 molecules were responsible for the binding activity since Hermes-1 antibodies that block the binding of hyaluronan to CD44 blocked the binding of [3H]hyaluronan to U-1752 cells. 4-Phorbol 12-myristate 13-acetate (PMA) treatment of U-1752 cells both increased the hyaluronan-binding activity in U-1752 cells as well as induced abrogation of cell-cell and cell-matrix interactions. Addition of hyaluronan inhibited the PMA-induced disassembly of the cells. The fact that CD44 molecules are able to bind [3H]hyaluronan only on the SCLC line U-1752 but not on other lung carcinoma cell lines may be of value as a marker for squamous cell carcinoma differentiation. Furthermore, the inhibitory effect of hyaluronan on the PMA-promoted cell disassembly suggest that hyaluronan surrounding squamous cell carcinoma cells may affect their migration and invasiveness.
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PMID:Functional hyaluronan receptors are expressed on a squamous cell lung carcinoma cell line but not on other lung carcinoma cell lines. 754 20

CD44 is a glycosylated adhesion molecule which may undergo alternative splicing of 10 possible exons to generate variant isoforms. A number of CD44 variant isoforms expressed by tumor cells have been correlated with metastatic and proliferative behavior. In this study, we have characterized CD44 isoform expression on three prostate cancer cell lines: ALVA-31, PPC-1, and LNCaP. Using reverse transcriptase-polymerase chain reaction, we have found that ALVA-31 and PPC-1 cells express multiple CD44 isoforms, including CD44s (standard form), CD44E (epithelial form), and an exon 14-containing form. In addition, two smaller forms have been detected: one using an alternative donor splice site within exon 5, and a novel form omitting exon 5 entirely. The CD44 isoforms expressed by ALVA-31 and PPC-1 cells appear to be preferentially located on the cell surface. By contrast, LNCaP cells do not express any of the CD44 forms at the RNA or protein level. Both PPC-1 and ALVA-31 cells display tumorigenesis and invasiveness in nude mice, whereas LNCap cells exhibit a less malignant phenotype, suggesting a correlation between CD44 variant (CD44v) expression and aggressive prostate tumor behavior. Functional characterization reveals that CD44 mediates prostate cell adhesion to extracellular hyaluronic acid (HA). In addition, the CD44 cytoplasmic domain binds specifically to ankyrin, a membrane cytoskeletal protein. Double immunofluorescence labeling and confocal microscopic analyses indicate that HA binding induces the HA receptor (i.e., CD44) to form capped structures. Importantly, intracellular ankyrin is preferentially accumulated underneath HA receptor-capped structures. These results suggest that cytoskeletal proteins such as ankyrin are closely associated with CD44-mediated signaling events induced by HA. Finally, HA-mediated transmembrane interactions between CD44 isoforms and cytoskeletal proteins (i.e. ankyrin) may play a pivotal role in regulating tumor cell behavior during human prostate cancer development.
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PMID:Interaction of CD44 variant isoforms with hyaluronic acid and the cytoskeleton in human prostate cancer cells. 754 57


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