Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CD44”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59Linked to original sources
PubMedDate not supplied

The predominant CD44 splice variant in prostate cancer binds fibronectin, and calcitonin stimulates its expression.

BACKGROUND: Prostate cancer (PC) consistently overexpresses variant the (v) isoform of the cell adhesion protein CD44, and loses expression of the standard (s) isoform. MATERIALS AND METHODS: We re-expressed CD44 full-length (exons 1-20) or standard (exons 1-5 + 16-20) or enforced stable RNAi against CD44v, and the examined functional effects on PC. The effect of stable knockout of calcitonin, a paracrine factor, or its receptor, on CD44 was assessed. RESULTS: Re-expression of full-length CD44 or CD44s increased the total CD44 mRNA and CD44s protein while suppressing CD44v. These approaches, and RNAi to CD44v, decreased invasion. In adhesion assays, benign prostate cells bound mainly to hyaluronan, whereas PC lost affinity for hyaluronan but bound more strongly to fibronectin. Re-expressing CD44s restored predominant hyaluronan binding. Knockout of the calcitonin receptor in PC-3 derived cells caused marked loss of CD44v expression and reversion to CD44s expression. CONCLUSION: Calcitonin influenced PC's balance between CD44s and CD44v. CD44v controlled invasiveness, altered ligand binding, and provides a target for therapeutic intervention.

Alternative Splicing↗
PubMed1990

Expression of the CD11/CD18, leukocyte adhesion molecule 1, and CD44 adhesion molecules during normal myeloid and erythroid differentiation in humans.

We have used three-color flow cytometry to investigate the pattern of expression of the CD11/CD18, CD44, and leukocyte adhesion molecule 1 (LAM-1) adhesion molecules during myeloid and erythroid differentiation in humans. The earliest myeloid cells, identified as CD33loCD15-, were exclusively CD44hi but contained both leukocyte function-associated antigen 1 (LFA-1hi) and LFA-1lo cells, as well as LAM-1+ and LAM-1- cells. This CD33loCD15- myeloid subpopulation expressed only low levels of CD11c and failed to express CD11b, CD14, or any lymphoid (CD3, CD16, CD19) antigens or glycophorin. Commitment to monocyte differentiation, suggested by the presence of an LFA-1hi CD11c+ subset within the CD33loCD15- subpopulation, was clearly signaled by upregulation of CD33; these monocyte-lineage committed cells were exclusively CD33hi, CD44hi, CD11ahi, CD11c+, and exhibited a broad range of intensity of CD15 expression. Later stages of monopoiesis were identified by acquisition of CD11b, and subsequently of CD14. Myeloid cells committed to granulopoiesis remained LFA-1lo, and underwent a sharp upregulation of CD15 along with downregulation of both CD33 and CD44. Successive stages of granulocyte development were marked by expression of CD11b and, subsequently, of CD16. The earliest cells capable of erythroid differentiation were CD44hi, LFA-1lo, and LAM-1+. Both LFA-1 and LAM-1 were lost before the onset of glycophorin (glyco) expression, whereas CD44 expression remained high on glyco+ cells, which also expressed CD45. CD44 expression was intermediate on glyco+ CD71+ cells, and low on glyco+ CD45- CD71- cells, similar to normal, circulating erythrocytes. Our results allow us to phenotypically define discrete stages in the normal development of monocytes, neutrophils, and erythrocytes. The expression of LFA-1, LAM-1, and high levels of CD44 on the most primitive hematopoietic cells detectable by flow cytometry suggests that at least some of these molecules are critically involved in leukocyte adhesion during development.

Antigens, Differentiation↗
PubMed1994

Applied Sciences: Absence of CD44-standard in human neuroblastoma correlates with histological dedifferentiation, N-myc amplification and reduced survival probability.

Expression of CD44 was examined by immunohistochemistry in 205 primary neuroblastomas together with histological grading according to the Shimada classification at the time of diagnosis. In addition, Southern blot analysis to determine N-myc gene amplification was carried out in the same tissue. When compared with clinical data such as stage, age and event-free survival probability it was found that CD44 expression characterizes well differentiated tumours and thus correlates with prognosis (event-free survival probability in CD44 positive patients 0.6 (n = 129) vs. 0.0 (n = 21) in CD44 negative patients). In tumours with N-myc = 1, CD44 positivity was found in 91% of patients as compared to 57% of patients with N-myc > 1 in tumours. All tumours of 13 patients with metastatic stage 4s (with good prognosis) showed CD44s expression. Thus, detection of CD44s expression might serve as a prognostic indicator which can be rapidly detected at diagnosis.

Journal Article↗
PubMed1990

Triggering of the CD44 antigen on T lymphocytes promotes T cell adhesion through the LFA-1 pathway.

The CD44 molecule, a molecule which has been previously known as Hermes, Pgp-1, extracellular matrix receptor III, and In(Lu)-related p80, is currently thought to be involved in several steps of normal immune cell function, including lymphocyte adhesion to high endothelial venules and to the extracellular matrix and T cell activation. We now demonstrate that triggering of CD44 on T lymphocytes by anti-CD44 mAb promotes cell adhesion. The induced homotypic adhesion is mediated by lymphocyte function-associated antigen-1 (LFA-1), because it was inhibited by anti-LFA-1 antibodies and not by anti-LFA-3 antibodies. This notion is supported by the temperature and Mg2+ dependence which is characteristic of LFA-1-mediated adhesion. Moreover, the sensitivity of CD44-induced adhesion to AMG and H7, which both prevent the activation of protein kinase C, and to cytochalasin B, which inhibits microfilament formation, suggests that the activation of the LFA-1 pathway via CD44 involves protein kinase C activation and requires an intact cytoskeleton.

Antibodies, Monoclonal↗
PubMed1994

Activated ras and src induce CD44 overexpression in rat intestinal epithelial cells.

CD44 is an adhesion molecule that is involved in the progression of several tumor types, including those originating in the intestine. There are several alternatively spliced forms of CD44. Here we show that intestinal epithelial cells express the standard form of CD44 (CD44s). The same form of CD44 is found in IEC-18, a cell line derived from normal rat intestinal crypts. Upon transfection of IEC-18 cells with ras or src, two oncogenes that are frequently activated in intestinal tumors, a significant induction of CD44s is observed. A causal role for ras in this induction is shown by using IEC clones transfected with an inducible ras expression vector. The oncogene-transformed IEC clones display a high degree of hyaluronic acid-dependent cell-cell adhesion that is not observed in the parental IEC-18 cells suggesting that ras- and src-induced overexpression of CD44 can alter the adhesion properties of intestinal cells.

Animals↗
PubMed1994

Inhibition of human melanoma growth and metastasis in vivo by anti-CD44 monoclonal antibody.

CD44 is a M(r) 90,000 surface glycoprotein believed to be involved in cell adhesion and migration. We investigated the role of CD44 in tumor growth and metastasis using human melanoma cell lines SMMU-1 and SMMU-2. Both SMMU-1 and SMMU-2 form tumors in the s.c. tissues when injected s.c. in SCID mice but only SMMU-2 metastasizes. Approximately one-half of SCID mice receiving injections of SMMU-2 s.c. develop metastatic tumors. SMMU-2 but not SMMU-1 expresses high levels of the hematopoietic form of CD44 and binds fluorescence-conjugated hyaluronic acid in vitro. GKW.A2 is a monoclonal antibody specific for human CD44 that can completely inhibit the binding of hyaluronic acid to SMMU-2 tumor cells in vitro. Moreover, in vivo injection of GKW.A3 inhibited the growth and metastatic potential of SMMU-2 tumor cells. Administration of GKW.A3 i.v. 1 week after s.c. tumor injection did not inhibit local tumor development but inhibited the formation of metastatic tumors and prolonged animal survival. Therefore, interactions between CD44 on tumor cells and its ligands in vivo may be necessary for tumor growth and metastasis.

Animals↗
PubMed1993

[Occurrence of CD44 and its isoforms under orthological and pathological conditions].

Variant isoforms of CD44 have been strongly implicated in malignant transformation and cancer metastasis. To ascertain the pattern of expression of these isoforms in human normal, fetal and tumor tissues (breast carcinomas, renal cell carcinomas, malignant melanomas, colon carcinomas, non-Hodgkin-lymphomas, neuroblastomas and brain tumors), we generated monoclonal antibodies against CD44 variant regions. Monoclonal antibodies were produced against variant regions encoded by exons 4v, 6v and 9v. CD44 variant isoforms are expressed on normal epithelial cells in a different pattern. Regions of epithelia that expressed the highest levels of the variant isoforms were those with a high rate of cell division. CD44 variant isoforms were not expressed by all investigated tumors (not by malignant melanomas, brain tumors and neuroblastomas). It is interesting that the expression of CD44 isoforms in non-Hodgkins lymphomas and colon carcinomas shows possibly a correlation with malignancy.

Antibodies, Monoclonal↗
PubMed1994

Normal human tissues, in addition to some tumors, express multiple different CD44 isoforms.

At least 20 different isoforms of the human CD44 lymphocyte-homing receptor/hyaluronan receptor have been described to date that arise from the differential splicing of up to 10 alternative exons (termed v1-v10) encoding the membrane-proximal extracellular domain. Although numerous analyses at the mRNA level have indicated tissue-specific expression of CD44 variants, few analyses have been performed at the protein level because of limited availability of suitable monoclonal antibodies. Recently, however, exon-specific monoclonal antibodies have been generated using bacterial fusion proteins, and these have been reported to detect high levels of vCD44 containing the v6 exon on human tumors. Together with earlier evidence linking this particular exon with tumor metastasis in the rat, these latter experiments have led to the interpretation that v6 splice variants play a causative role in tumor dissemination. In this paper we describe the use of a new and comprehensive panel of CD44 exon-specific monoclonal antibodies generated against a recombinant CD44(v3-10)-immunoglobulin chimera to study vCD44 expression in a large number of normal and neoplastic tissues. We show that the expression of vCD44 varies greatly among different human tumors and that some express either very low levels of vCD44 or no CD44 at all. Furthermore, we demonstrate that expression is not limited to isoforms containing the v6 exon but includes variants carrying v3, v4/5, and v8/9. Additionally, normal epithelial tissues are shown to express considerable levels of these same vCD44 isoforms. Such results argue against a ubiquitous role for vCD44 isoforms in promoting tumor growth and metastasis.

Antibodies, Monoclonal↗
PubMedDate not supplied

Expression of integrin and CD44 adhesion molecules on neuroblastoma: the relation to tumor aggressiveness and embryonic neural-crest differentiation.

The immunohistological expression of integrins and CD44 cell adhesion molecule was analyzed on neuroblastoma (NB) specimens to study the potential role of these molecules in normal differentiation and in the transformation of neural crest derivatives. None of the specimens expressed the alpha 5 beta 1 integrin heterodimer; the expression of alpha 3 beta 1 heterodimer was maintained during all stages of differentiation; alpha 1 beta 1 heterodimer was expressed on undifferentiated neuroblasts and on Schwann cells, but was lost on ganglion cells. In contrast alpha 2 beta 1, alpha 6 beta 1, alpha 6 beta 4 and alpha V beta 1 expression was usually restricted to cells differentiated in the Schwann cell lineage. Alpha V beta 3 was expressed on tumors developed in the mediastinum. CD44 was strongly detected on differentiated ganglioneuroblastomas, stage 1 and 2 ganglioneuromas, as well as low-grade stage 4S NB and normal neuroblasts migrating in the fetal adrenal gland. CD44 expression was observed on Schwann cells and ganglion cells; in contrast, it was expressed on only 50% stage 3 and 4 undifferentiated NB. None of these specimens expressed exons V5, V7 or V6. In a few specimens, an intracellular expression of exons V8-V10 was observed in ganglion cells. The expression of CD44 on NB may reflect its pattern of expression on sympatho-adrenal precursors and arrest differentiation at these stages. Conversely, CD44 expression may be silenced during malignant transformation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[Expression of CD44 alternative splicing variants in lung cancer].

Expression of isoforms of the CD44 is generated by alternative splicing of CD44 gene; CD44H: lacks all 10 alternative exons, CD44R: the alternative exons v8 to v10, CD44V: other group of variants which contains the alternative exon v6. In some tumors such as colorectal cancer, breast cancer, non-Hodgkin lymphoma, and melanoma, over-expressed CD44 isoform which contains such alternative-spliced variant exons may play a causative role in tumor metastasis. In lung cancer, however, the role of CD44 variants in tumor progression and metastasis is uncertain. In our study and reported literature, no definite correlation was observed between the expression of specific CD44 isoform and tumor progression or metastasis of lung cancer.

Alternative Splicing↗
PubMed1995

[Expression of CD44 variant form in human renal cell carcinoma].

To examine whether renal cell carcinoma display altered CD44 expression we performed reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of CD44 in the tissues resected from 19 patients with renal cell carcinoma and 6 renal cancer cell lines. To detect the CD44 variants, we utilized the RT-PCR Southern blot method reported by Matsumura et al. In 12 of 17 (70.6%) cases, about a 700 base pairs band was emphasized in cancerous tissues compared with normal kidney. Moreover, we found that this isoform is the CD44 variant sharing only exon v10. Examination by Northern blot analysis has revealed that all tumors express a higher level of CD44 variants sharing exon v10. Our findings suggest that this variant form plays some roles in renal cell carcinoma.

Base Sequence↗
PubMed1993

The identification of a new alternative exon with highly restricted tissue expression in transcripts encoding the mouse Pgp-1 (CD44) homing receptor. Comparison of all 10 variable exons between mouse, human, and rat.

The human CD44 cell surface glycoprotein family which has been implicated in lymphocyte homing, tumor metastasis, and extracellular matrix attachment consists of a large number of related isoforms that derive from the differential splicing of a single CD44 gene transcript. Recent mapping of the CD44 locus in man indicated the presence of at least nine alternative exons within the region of the gene encoding the variable membrane proximal extracellular domain. Here we report the identification of a 10th alternative exon (termed V1) in the mouse, human, and rat CD44 genes. We demonstrate tissue-specific patterns of expression for transcripts containing exons V1-V10 in the mouse and a highly restricted usage of exon V1 in transcripts from mouse gastric tissue. Close sequence homology between exons V1-V10 from mouse rat and human points to a specific functional role rather than a purely structural role for the membrane proximal extracellular domain of the CD44 molecule.

Alternative Splicing↗
PubMed1995

[Expression of CD44 isoforms in normal human liver and also in regenerative and neoplastic liver changes].

CD44 is a transmembrane glycoprotein of which a large number of isoforms exist. There is evidence, mostly from experimental systems, that isoforms of CD44 generated by alternative splicing of ten variant exons are involved in tumor invasion and metastasis formation. We have evaluated the expression of CD44 standard (CD44s) and variant exons (CD44v) encoded gene products in formalin-fixed and paraffin-embedded human liver specimens, using an immunohistochemical protocol with microwave-based antigen-retrieval and signal amplification. Tissue sections from normal, regenerative and neoplastic liver were studied. Our results indicate that: 1. in normal liver, both, hepatocytes and bile duct epithelia lacked detectable CD44s and CD44v containing isoforms; 2. most cirrhotic liver specimens were unreactive. Some regenerative nodules showed a focal weak positivity for CD44v5 and v9. Most proliferating bile ductules were weakly stained for CD44v9 and some of them also for v5 and v6; 3. most hepatocellular carcinomas displayed a heterogeneous staining of varying intensity for CD44v5, v6, v9 and CD44s. In a few tumors a weak staining for CD44v3 and v4 was also present. Furthermore, there was a tendency to an increased staining intensity of CD44 isoforms with decreasing differentiation; 4. cholangiocarcinomas showed a high expression of CD44s, v3, v5, v6 and v9 containing isoforms. We conclude that neoplastic transformation of hepatocytes and bile duct epithelia is associated with qualitative and quantitative changes in the expression of some CD44 variant exons encoded products. The clinical implications of these findings remain to be determined in a large series of patients.

Adenoma↗
PubMed1996

Progressive loss of CD44 gene expression in invasive bladder cancer.

This study investigated CD44 gene expression at both the RNA and protein level in well differentiated superficial and in deeply invasive bladder carcinomas. Proteins were studied by immunohistochemistry using antibodies against standard (CD44s) and variant (CD44v) isoforms. mRNA was analyzed by reverse transcriptase polymerase chain reaction/Southern blotting and in situ hybridization. Immunostaining with antibodies against CD44s and CD44v2, -5 and -6 (exons 7, 10, and 11, respectively) showed that carcinoma cells in all papillary tumors expressed strong signals throughout the epithelium but especially in the basal layer, which abuts on the stroma. However, invasive tumors, which are believed to originate mainly from flat urothelial tumors or, less frequently, from papillary carcinomas, progressively lost CD44 proteins as they penetrated deeper and became less differentiated. This change was paralleled at the mRNA level, by the gradual loss of expression of CD44s and CD44v transcripts in deeply invasive tumors until they were virtually undetectable. Conversely, papillary tumors contained multiple higher molecular weight transcripts, suggesting that the loss of CD44 proteins in the more aggressive tumors is due to a disturbance in transcription. This concept was confirmed by in situ hybridization studies with a probe showing that substantial variant CD44 mRNA is located in the urothelium in papillary carcinomas but is absent from deeply invasive carcinomas. These results indicate that initially there is a striking increase in CD44 gene expression in early bladder carcinomas, relative to normal urothelium, but that this diminishes as the tumors acquire a more aggressive phenotype.

Base Sequence↗
PubMed1997

CD44 is a metastasis suppressor gene for prostatic cancer located on human chromosome 11p13.

We have used microcell fusion-mediated chromosomal transfer to introduce normal human chromosomes into highly metastatic rodent prostatic cancer cells to map the location of a metastasis suppressor gene(s). Using this approach, several chromosomal regions have been identified that harbor such metastatic suppressor genes, including human chromosome 11 between p11.2-13 (T. Ichikawa et al., Cancer Res., 52: 3486-3490, 1992, 54: 2299-2302, 1994; N. Nihei et al., Genes Chromosomes & Cancer, 14: 112-119, 1995; C. W. Rinker-Schaeffer et al., Cancer Res., 54: 6249-6256, 1994). Using positional cloning, a metastatic suppressor gene, termed KAI1, was identified, which is located at human chromosome 11p11.2 (5). Overexpression of KAI1 results in metastasis suppression in certain highly metastatic Dunning R-3327 rat prostatic cancer sublines, such as AT6.1, without metastasis suppression in other highly metastatic sublines, such as AT3.1. This suggests that an additional metastasis suppressor gene is located within the human chromosome 11p11.2-13 region. The CD44 gene is located on human chromosome 11p13 and encodes an integral membrane glycoprotein that participates in specific cell-cell and cell-extracellular matrix interactions. Down-regulation of CD44 expression both at the mRNA and protein levels correlates with metastatic potential within the Dunning system of rat prostatic cancer sublines. Transfection-induced enhanced expression of the Mr 85,000 standard form of CD44 in the highly metastatic AT3.1 rat prostatic cells greatly suppresses their metastatic ability to the lungs without suppression of their in vivo growth rate or tumorigenicity. These results suggest that CD44 is a metastasis suppressor for prostatic cancer and that decreased expression of the standard form of CD44 is involved in the progression of prostatic cancer to a metastatic state.

Animals↗
PubMedDate not supplied

Benzyl-alpha-GalNAc inhibits sialylation of O-glycosidic sugar chains on CD44 and enhances experimental metastatic capacity in B16BL6 melanoma cells.

We examined the effect of benzyl-alpha-N-acetylgalactosamine (benzyl-alpha-GalNAc), which specifically inhibits the synthesis of O-linked oligosaccharides, on the expression of the peanut agglutinin (PNA)-binding sugar chains (Gal beta 1-3GalNAc) of CD44 and on its experimental metastatic ability in B16BL6 melanoma. Benzyl-alpha-GalNAc increased the PNA-binding, but not Concanavalin A (Con A), wheat germ agglutinin (WGA), and leukoagglutinating phytohemaagglutinin (L-PHA)-binding to the cell surface. Benzyl-alpha-GalNAc markedly increased the PNA-binding to CD44 by decreasing the sialylation of these sugar chains. The experimental metastatic ability of B16BL6 cells was enhanced in association with this modulation of the sugar chains. These findings suggested that unsialylated Gal beta 1-3GalNAc sugar chains on the cell surface and/or CD44 are involved in the metastatic process of B16BL6 melanoma cells. On the other hand, the known functions of CD44, such as adhesion to hyaluronate, fibronectin, collagen, and endothelial cells, as well as homotypic aggregation, were not affected by benzyl-alpha-GalNAc regardless of the enhancement of metastatic ability induced by this glycosylation inhibitor. CD44 might have other metastasis related functions that remain to be elucidated.

Acetylgalactosamine↗
PubMed1997

Origin and function of circulating CD44 in non-Hodgkin's lymphoma.

Soluble isoforms of various adhesion molecules have recently been found in the circulation, but the physiologic effects of such molecules are still unconfirmed. Our earlier study suggests that the serum level of the 70- to 80-kDa form of CD44 (sCD44) parallels the clinical treatment response in patients with lymphoma. In the present study we investigated the origin and the function of sCD44 in non-Hodgkin's lymphoma. Both peripheral blood and tumor lymphocytes were able to shed soluble CD44 in cell culture. In a SCID mouse model, transplanted Burkitt lymphoma (Namalwa) cells transfected with human CD44 shed soluble CD44. In binding studies sCD44 was able to adhere to hyaluronate and fibronectin, and moreover, sCD44 was able to block the binding of hyaluronate to CD44 on the cell surface and to block the binding of lymphocytes to high endothelial venules, suggesting that sCD44 retains its biological activity although it does not contain the cytoplasmic tail. In conclusion, sCD44 is biologically active and is at least partially shed by lymphoma cells in non-Hodgkin's lymphoma patients.

Animals↗
PubMedDate not supplied

CD44 is involved in migration but not spreading of astrocytoma cells in vitro.

Local tumour-cell invasiveness, which is a major morphological feature of astrocytomas, involves interactions between tumour cell and extracellular matrix (ECM) including adhesion, proteolysis, and migration of tumour cells through the locally modified microenvironment. These interactions are mediated by cell/cell and cell/substrate adhesion molecules. We have earlier demonstrated that the adhesion molecule CD44 is expressed on gliomas and plays a role in adhesive interactions between glioma cells and a wide range of ECM components. In the present in vitro study we have further investigated the possible role of CD44 in subsequent stages of cell/ECM interactions-spreading and migration, using the GCCM anaplastic astrocytoma cell line. We have demonstrated that cell spreading is more effective on fibronectin (FN) than hyaluronan (HA) with a mean cell perimeter of 185 microns when cells are grown on FN as compared to 66 microns on HA. Antibody blockade experiments indicated that CD44 is not involved in cell spreading on either substrate. In the in vitro migration assay the tumour cells displayed a 2.5 fold greater migration rate through HA-coated as compared to FN-coated polycarbonate membranes. Blocking of CD44 by specific monoclonal antibody resulted in an inhibition of migration by 56% on HA providing evidence that CD44 plays a role in migration of astrocytoma cells in vitro.

Astrocytoma↗