Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Monolayers of endothelial cells (EC) cultured from mouse lymph nodes were exposed to controlled levels of shear stress (0-7.1 dyn/cm2) in a parallel plate flow chamber, and binding between the flow-loaded EC and mouse lymph node-derived lymphocytes was assayed. A large number of lymphocytes adhered to the stationary control EC, but in EC exposed to a shear stress of 1.5 dyn/cm2 for 6 h, the adhesion decreased to 68.8 +/- 12.8% (SD; n = 19) of control (n = 29, P < 0.001). The decrease in adhesion induced by flow loading was time and shear stress dependent and reversible. Treatment of stationary EC with a monoclonal antibody (MAb) to vascular cell adhesion molecule-1 (VCAM-1) reduced the adhesion to 70.6 +/- 11.5% (n = 19) of control (P < 0.001), whereas MAb to CD44 and to intercellular adhesion molecule-1 had no effect on it. Flow cytometric analysis revealed that the amount of VCAM-1 expressed on the cell surface was decreased to 48.5 +/- 15.8% (n = 6) of control by flow loading (P < 0.001). Flow loading experiments using two perfusates with different viscosities demonstrated that the decrease in VCAM-1 expression due to flow was shear stress rather than shear rate dependent. The detection of mRNA by reverse transcriptase-polymerase chain reaction showed that VCAM-1 mRNA levels were markedly depressed in EC exposed to flow loading.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Shear stress inhibits adhesion of cultured mouse endothelial cells to lymphocytes by downregulating VCAM-1 expression. 752 33

Changes in the CD44 variant (CD44v) isoforms on the cell surface have been correlated with tumor metastasis. In this study we have examined the expression of CD44 variant isoforms in human breast carcinoma samples by a variety of techniques including immunohistochemistry, reverse transcriptase-polymerase chain reaction (RT-PCR), and nucleotide sequencing. Using RT-PCR, we have determined that normal human breast tissue contains primarily the CD44 epithelial (CD44E) form and very little CD44 standard (CD44s) form. However, metastatic breast carcinomas appear to overexpress both the CD44E and CD44s forms and also display multiple new species of CD44 variant isoforms. Histocytochemical staining using anti-CD44 antibody (recognizing a common determinant of the CD44 class of glycoproteins) confirms that the CD44 molecules are overexpressed and preferentially located in metastatic breast cancer tissues. Nucleotide sequencing analyses indicate that at least four new CD44 variant isoforms (i.e., displaying unique splicing via the insertion or the deletion of exons 7, 10, 11, and 14) may be closely associated with human metastatic breast cancers. These newly described CD44 variant isoforms may be useful for monitoring the progression of human breast cancer metastasis.
 ...
PMID:New CD44 splice variants associated with human breast cancers. 752 35

This study was undertaken to determine whether blood flow modulates the adhesive property of vascular endothelial cells to lymphocytes and, if it does, what adhesion molecules are involved. Cultured mouse endothelial cells were exposed to medium flow in a parallel plate chamber, and binding assay using fluorescence-labeled lymphocytes was carried out. The adhesion rate of endothelial cells to lymphocytes, which was high in the static control state, decreased when exposed to shear stress (1.5 dynes/cm2) for 6 h. The treatment of static endothelial cells with a monoclonal antibody of vascular cell adhesion molecule-1 (VCAM-1) depressed the adhesion rate to the same extent as that caused by flow, while monoclonal antibodies of CD44 and intercellular adhesion molecule-1 had no effect on it. Flow cytometric analysis revealed that the application of flow decreased markedly the amount of VCAM-1 expressed on the cell surface. A reverse transcriptase-polymerase chain reaction of mRNA showed that flow depressed VCAM-1 mRNA levels. These results suggest that blood flow can modulate the adhesive property of endothelial cells to lymphocytes via affecting the surface expression of adhesion molecules, e.g., down-regulation of VCAM-1.
 ...
PMID:Down-regulation of vascular adhesion molecule-1 by fluid shear stress in cultured mouse endothelial cells. 753 26

The cell-surface receptor for hyaluronic acid, CD44, is expressed by both normal and malignant cells. Numerous CD44 isoforms have recently been identified that are derived by alternative ribonucleic acid splicing. The expression of some CD44 isoforms has been shown to be involved in tumor progression and metastatic spread in a rat carcinoma model and in human carcinomas. In the present study, CD44 isoform expression was evaluated by reverse transcriptase-polymerase chain reaction (PCR) analysis in frozen sections derived from three samples of normal brain tissue and from 40 brain tumors, including samples of glioblastoma multiforme, anaplastic astrocytoma, low-grade astrocytoma, cerebral primitive neuroectodermal tumor, medulloblastoma, metastatic colon carcinoma, and metastatic melanoma. Normal brain tissue adjacent to the tumors was also examined in 14 of 18 glioblastomas. In all normal brain and tumor samples, with the exception of metastases from colon carcinoma, PCR analysis demonstrated one prominent product that corresponded to the CD44H hematopoietic form of CD44. Metastases from colon carcinoma demonstrated two prominent PCR amplification products corresponding to CD44H and CD44R1. These results suggest that CD44H is the predominant isoform of this protein in normal human brain tissue and in human neuroectodermal tumors of varying degrees of malignancy. The ability of CD44H to mediate tumor cell motility and invasiveness (in contrast to CD44R1) suggests that the CD44 alternative splicing pattern of neuroectoderm-derived tumors may enhance their local biological aggressiveness and intracerebral spread. The lack of expression of larger molecular weight CD44 variants by primary brain tumors may also partially explain why these tumors rarely metastasize to distant sites.
 ...
PMID:Alternative RNA splicing of the hyaluronic acid receptor CD44 in the normal human brain and in brain tumors. 753 36

CD44 is the transmembrane adhesion molecule which binds hyaluronate. The gene encoding CD44 is found on chromosome 11p and comprises 20 exons. Differential splicing of the 10 extracellular juxtamembranous exons (v1-10) generates the major isoforms of CD44. The major CD44 isoform found on hematopoetic cells (CD44s) contains none of the variably expressed exons, while the major isoform expressed on epithelial cells [CD44(v8-10)] contains exons v8-10. Metastasis-specific isoforms of CD44 were first documented in a model of rat pancreatic adenocarcinoma [CD44(v4-7), CD44(v6-7)] and subsequently in other cancers. This study is the first characterization of CD44 isoforms in primary and metastatic human pancreatic adenocarcinomas. CD44 isoforms were analyzed in specimens of 15 primary and 6 metastatic pancreatic adenocarcinomas as well as in 6 specimens of control pancreata by two different methods. Radiolabeled reverse transcriptase-PCR coupled with 8% PAGE allowed analysis of the major isoforms of CD44, while Southern blot hybridization with [alpha-32P]dCTP-labeled probes permitted analysis for metastasis-specific CD44 isoforms containing CD44(v6) or CD44(v8-10). No differences in the expression of CD44(v8-10) and CD44s were found among the primary and metastatic pancreatic adenocarcinomas, and control specimens of pancreata. However, a novel CD44(v6) isoform was found in metastatic lesions and may represent the human homologue of the rat pancreatic adenocarcinoma metastasis-associated CD44 isoform.
 ...
PMID:CD44 isoform expression in primary and metastatic pancreatic adenocarcinoma. 753 74

CD44 is a glycosylated cell surface adhesion molecule expressed on a diverse range of cells and has several variant forms, some of which are involved in metastasis of cancer cells. Because little is known about CD44 in human hepatocellular carcinoma (HCC), we investigated its expression in tissue specimens from primary lesions (12 cases), in smear specimens from peritoneal effusions (2 cases), and in cell lines (HCC cell lines, KIM-1, KYN-1, KYN-2, KYN-3, HAK-1A, and HAK-1B; combined hepatocholangiocarcinoma cell lines, KMCH-1 and KMCH-2; and bile duct carcinoma cell lines, KMC-1 and KMBC). Immunohistochemical studies using monoclonal antibody recognizing epitope Group 1 of human CD44 molecule showed that HCC cells in all tissue specimens, including the original tumors of one smear specimen and HAK-1A, were negative for CD44; whereas, HCC cells in two-smear specimens, KIM-1, KYN-2, KYN-3, HAK-1A, HAK-1B, KMCH-1, KMC-1, and KMBC, showed positive reactions on the cell membrane. Immunostain-positive cell lines showed a positive cell rate of 51.9% to 99.8% by flow cytometric analysis. Western blotting detected CD44 protein of hemopoietic type in KIM-1, KYN-3, HAK-1A, and HAK-B and epithelial type in KMC-1 and KMBC. Southern blotting of complementary DNA amplified after reverse transcriptase-polymerase chain reaction (RT-PCR) detected hemopoietic type and some variant forms with longer insertion in all cell lines but KMCH-2, whereas hemopoietic type and variants with minor insertion were only detectable in tissue specimens. These findings suggest that HCC cells in ascites and in culture often express CD44, but those in tissue do not at protein level.
 ...
PMID:Expression of CD44 in human hepatocellular carcinoma cell lines. 753 11

Isoforms of the transmembrane glycoprotein CD44, generated by alternative RNA splicing, have been correlated to tumor dissemination. For evaluation of the potential role of CD44 variant isoforms in non-Hodgkin's lymphoma (NHL), the presence of CD44 isoforms was analyzed in a large panel of reactive and neoplastic lymphoid tissues by immunohistochemical staining, as well as detection of CD44 variant RNAs by the reverse transcriptase-polymerase chain reaction. Whereas the CD44 standard or hematopoietic isoform (CD44s), devoid of the variant regions, was expressed in all leukocyte subpopulations, the variant isoforms (CD44v) showed a highly restricted pattern of expression, mainly observed in epithelial layers of lymphoid tissues and subpopulations of leukocytes after stimulation. In addition to a strong expression of CD44s, variant isoforms containing CD44-6v in combination with other variant exons were observed predominantly in aggressive lymphoma and were associated with a shorter overall survival of patients (n = 138; P < .0001). Moreover, multivariate analysis indicated CD44-6v as a new independent prognostic parameter in high grade NHL in comparison with the risk groups defined by the International NHL Lymphoma Prognostic Factors Project (N Engl J Med 329:987, 1993).
 ...
PMID:CD44 variant isoforms in non-Hodgkin's lymphoma: a new independent prognostic factor. 753 83

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.
 ...
PMID:Interaction of CD44 variant isoforms with hyaluronic acid and the cytoskeleton in human prostate cancer cells. 754 57

We have recently identified a new exon of the CD44 gene and demonstrated abnormal retention of a noncoding section, intron 9, in mRNA from bladder carcinomas. To analyze this further, the present study examined CD44 gene expression in cell lines from 14 esophageal, 3 colonic, and 4 breast carcinomas and in fresh samples from 20 colorectal carcinomas and corresponding normal colonic mucosa, using reverse transcriptase followed by the polymerase chain reaction (RT-PCR). This confirmed that there was abnormal assembly of several exons of the gene in cell lines and in tumor tissues from these organs. However, the most striking new finding was that intron 9 was present in RNA from 11 esophageal, 3 colon, and 1 breast carcinoma cell line, respectively. This was confirmed by RNase and DNase digestion analysis. Moreover, it was detected both in nuclear and cytoplasmic mRNA fractions, indicating that abnormal splicing of pre-mRNA occurs in cancer cells. The abnormal retention of intron 9 in CD44 gene transcripts was also demonstrated in tumor tissues from 16 (80%) of 20 patients with colon carcinoma, but there was no correlation with Dukes' stage. The biological significance of these observations is not yet understood. However, it is clear that, as with the abnormal expression pattern of CD44 variant exons, intron 9 retention is a good-candidate molecular diagnostic tool for colorectal carcinomas.
 ...
PMID:Abnormal retention of intron 9 in CD44 gene transcripts in human gastrointestinal tumors. 754 38

CD44 is a polymorphic family of immunologically related cell surface proteoglycans and glycoproteins implicated in cell-cell and cell-matrix adhesion interactions, lymphocyte activation and homing, cell migration, and tumor metastasis. CD44 exists as a standard form and as multiple isoforms, each generated by alternative splicing of up to 10 variant exons (termed v1-v10) encoding parts of the extracellular domain. Using semiquantitative reverse transcriptase-PCR and Southern hybridization, alternative CD44 mRNA splicing was examined in 10 papillary thyroid carcinomas, 8 nodular goiters, 9 adenomas, 2 cases of thyroiditis, and 3 histologically normal thyroid controls. The amount of input cDNA for the CD44 PCRs was standardized against an internal control gene (glyceraldehyde phosphate dehydrogenase). Four papillary carcinomas showed significant overexpression of CD44 transcripts migrating between 750 and 1000 bp. These cases demonstrated reduced levels of the 482-bp standard isoform transcript. In six papillary cancers, we found a prominent v6-containing isoform at 750 bp that was present in only trace amounts in normal thyroid tissue. It is of interest that similar findings were seen in the majority of the goiters and adenomas but not in the cases of thyroiditis. These results show that deregulation of alternative CD44 splicing is a common feature of disordered thyroid follicular cell growth, both in neoplastic and nonneoplastic lesions. The data imply an important role for CD44, including CD44v6, in the pathogenesis of various thyroid lesions.
 ...
PMID:Deregulated alternative splicing of CD44 messenger RNA transcripts in neoplastic and nonneoplastic lesions of the human thyroid. 755 35


1 2 3 4 5 6 7 8 9 10 Next >>