Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0178874 (tumor progression)
 40,807 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

CD44 is a transmembrane glycoprotein occurring in several isoforms with different extracellular regions. The various transcripts are encoded by one gene locus containing 20 exons, of which at least 10 can be alternatively spliced in nascent RNA. Isoforms encoded by the variant exons (termed CD44v) are highly restricted in their distribution in nonmalignant tissue as opposed to the standard form of CD44 (CD44s) abundant in many tissues. Specific variant isoforms containing exon 6v have been shown to render nonmetastatic rat tumor cells metastatic. Based on the prominent role in rat metastasis formation, CD44v isoforms were suggested to be involved in human tumor progression. Correlations between prognosis and expression of CD44v have been reported for gastric and colon carcinoma, for non-Hodgkin's lymphoma, and recently for breast carcinoma. We evaluated the expression of CD44 isoforms in node-positive (n = 119) and node-negative (n = 108) cases of breast carcinoma by immunohistochemistry using CD44v exon-specific mAbs. In a subset of 43 cases of high-risk patients, reverse transcription-PCR was used to determine the exon composition of the transcripts. Protein and RNA expression data were probed statistically for their correlation to survival of the patients and clinical risk factors. In contrast to recently published data (M. Kaufmann et al., Lancet, 345: 615-619, 1995), in our cohort disease-free and overall survival data did not indicate significant correlations with the expression of the analyzed isoforms in univariate and multivariate analyses. Comparison of CD44 protein expression with established clinical risk factors for survival such as tumor size (pT1+pT2) and histological grading revealed correlations with the presence of CD44s (P = 0.02 and P = 0.03, respectively) and CD44-9v (P = 0.05 for histological grading). Carcinoma tissues with elevated estrogen and progesterone receptor levels showed positive correlation with CD44-6v (P = 0.001), while a trend for significant coexpression of CD44s and CD44-9v isoforms was observed in estrogen receptor-positive tissues (P = 0.08 and 0.06, respectively). In breast cancer, CD44s, CD44-9v, and CD44-6v are apparently markers for cellular differentiation but not for tumor progression. Our data suggest that steroid hormone receptors may be associated with the in vivo expression of CD44-6v-containing isoforms in human mammary carcinoma.
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PMID:CD44 isoforms correlate with cellular differentiation but not with prognosis in human breast cancer. 758 12

CD44 cell-surface receptor expresses multiple isoforms, some of which are believed to play a role in tumor growth and metastasis. The CD44 gene is composed of 19 exons, of which 9 (exons 6 to 14) are alternatively spliced to form inclusions in the intervening membrane proximal region. Sequences present in the shortest metastatic variant cloned from a rat metastatic cell line have been shown to correspond to human exons 10 and 11, also called exons v6 and v7. Using RT-PCR, we have addressed in detail the CD44 isoforms produced in human breast and colon tumors. We analyzed 53 breast-tumor- and 58 colon-tumor-related samples as well as 1 benign mastopathy, 1 normal breast, 4 non-invaded lymph nodes and 8 normal colon tissues. All tumors analyzed expressed the hemopoietic CD44 (CD44H) isoform (no alternatively spliced exons added), whereas 81% expressed the CD44E form (addition exons 12, 13 and 14). Furthermore, 85% of tumors presented complex patterns of expression, with an average number of 5 to 6 bands detected. In view of their implication in the metastatic process, we investigated in greater detail the isoforms containing exons 10 and 11 (v6 and v7). Exon 10 was more frequently expressed than exon 11, 80% and 57% of the samples respectively. The great majority of cases showed ladder-like patterns starting from the shortest forms (exons 5-10 or 5-10-11) and larger-molecular-weight bands corresponding predominantly to sequential inclusions of exons from 3' to 5'. Exon-10 and exon-11 variants were also found in one benign mastopathy. The majority of normal tissues (1 breast and 6/8 colon) expressed only the CD44H isoform. These data indicate that expression of metastatic variants is common in human breast and colon tumors and can occur early during cancer progression, as testified by their presence in a benign breast tumor. While expression of exon-10 variants were correlated with presence of distal metastases in colon tumors, exon-11 variants were not (metastatic events were too rare in our breast-tumor series to reach significance). This suggest that exon 10 may correspond to the minimal sequences required to favor metastatic events.
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PMID:CD44 expression patterns in breast and colon tumors: a PCR-based study of splice variants. 759 9

We examined expression of prostate-specific membrane antigen (PSM) mRNA in normal prostate using reverse transcription-PCR and sequencing. An alternatively spliced variant, PSM', along with the previously described PSM form, was found in normal prostate. PSM' cDNA is shorter (2387 nucleotides) than PSM (2653 nucleotides). The cDNAs are identical except for a 266-nucleotide region near the 5' end of PSM cDNA (nucleotide 114-380) that is absent from PSM'. This deleted region includes the translation initiation codon and codons for the putative transmembrane domain of PSM. Thus, PSM' RNA codes for a protein that has no apparent signal sequence. We verified the existence of spliced mRNA variants in human primary tissue specimens by RNase protection assay. In LNCaP human prostatic cancer cells and in primary prostate tumors, PSM is the dominant form. In contrast, normal human prostate expressed more PSM' than PSM. Benign prostatic hypertrophy samples showed about equal expression of both variants. We quantified the relative expression of each variant by densitometry and compiled a tumor index, which is the ratio of PSM:PSM' level. LNCaP has an index ranging from 9-11, carcinoma of the prostate from 3-6, benign prostatic hypertrophy from 0.75-1.6, and normal prostate from 0.075-0.45. The index reflects the increased expression of PSM over PSM' following the progression from normal to tumor state. This tumor index may be a useful indicator for the measurement of tumor progression. PSM and PSM' may be functionally different proteins as a result of differences in structure or cellular location. We are investigating the prevalence of one form over the other and how it may influence tumor progression.
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PMID:Alternatively spliced variants of prostate-specific membrane antigen RNA: ratio of expression as a potential measurement of progression. 788 49

Tumor stroma is a specialized form of tissue that is associated with epithelial neoplasms. Recent evidence indicates that significant changes in proteoglycan content occur in the tumor stroma and that these alterations could support tumor progression and invasion as well as tumor growth. Our main hypothesis is that the generation of tumor stroma is under direct control of the neoplastic cells and that, via a feedback loop, altered proteoglycan gene expression would influence the behavior of tumor cells. In this review, we will focus primarily on the work from our laboratory related to the altered expression of chondroitin sulfate proteoglycan and its role in tumor development and progression. The connective tissue stroma of human colon cancer is enriched in chondroitin sulfate and the stromal cell elements, primarily colon fibroblasts and smooth muscle cells, are responsible for this biosynthetic increase. These changes can be reproduced in vitro by using either tumor metabolites or co-cultures of human colon carcinoma cells and colon mesenchymal cells. The levels of decorin, a leucine-rich proteoglycan involved in the regulation of matrix assembly and cell proliferation, are markedly elevated in the stroma of colon carcinoma. These changes correlate with a marked increase in decorin mRNA levels and a concurrent hypomethylation of decorin gene, a DNA alteration associated with enhanced gene expression. Elucidation of decorin gene structure has revealed an unexpected degree of complexity in the 5' untranslated region of the gene with two leader exons that are alternatively spliced to the second coding exon. Furthermore, a transforming growth factor beta (TGF-beta)-negative element is present in the promotor region of decorin gene.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Altered proteoglycan gene expression and the tumor stroma. 829 47

Tumor stroma is a specialized form of tissue that is associated with epithelial neoplasms. Recent evidence indicates that significant changes in proteoglycan content occur in the tumor stroma and that these alterations could support tumor progression and invasion as well as tumor growth. Our main hypothesis is that the generation of tumor stroma is under direct control of the neoplastic cells and that, via a feedback loop, altered proteoglycan gene expression would influence the behavior of tumor cells. In this review, we will focus primarily on the work from our laboratory related to the altered expression of chondroitin sulfate proteoglycan and its role in tumor development and progression. The connective tissue stroma of human colon cancer is enriched in chondroitin sulfate and the stromal cell elements, primarily colon fibroblasts and smooth muscle cells, are responsible for this biosynthetic increase. These changes can be reproduced in vitro by using either tumor metabolites or co-cultures of human colon carcinoma cells and colon mesenchymal cells. The levels of decorin, a leucine-rich proteoglycan involved in the regulation of matrix assembly and cell proliferation, are markedly elevated in the stroma of colon carcinoma. These changes correlate with a marked increase in decorin mRNA levels and a concurrent hypomethylation of decorin gene, a DNA alteration associated with enhanced gene expression. Elucidation of decorin gene structure has revealed an unexpected degree of complexity in the 5' untranslated region of the gene with two leader exons that are alternatively spliced to the second coding exon.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Altered proteoglycan gene expression and the tumor stroma. 850 May 99

The alternatively spliced fibroblast growth factor receptor (FGFR)-1 isoforms, FGFR-1alpha and FGFR-1beta, are characterized by the presence of either three or two Ig-like loops in the extracellular domain and are differentially expressed during embryonic development and tumor progression. We have previously shown that in cells irreversibly committed to DNA synthesis by FGF-1, approximately 15% of cell surface FGFR-1 traffics to a perinuclear locale as a structurally intact and functional tyrosine kinase (Prudovsky, I., Savion, N., Zhan, X., Friesel, R., Xu, J., Hou, J., McKeehan, W. L., and Maciag, T. (1994) J. Biol. Chem. 269, 31720-31724). In order to define the structural requirement for association of FGFR-1 with the nucleus, the expression and trafficking of FGFR-1 in FGFR-1alpha and FGFR-1beta L6 myoblast transfectants was studied. Although FGFR-1alpha was expressed as p145 and p125 forms, FGFR-1beta was expressed as p120 and p100 forms in the L6 myoblast transfectants. Tunicamycin and N-glyconase experiments suggest that these forms of FGFR-1alpha and FGFR-1beta are the result of differential glycosylation. However, only the p145 form of FGFR-1alpha and the p120 form of FGFR-1beta were able to bind FGF-1 and activate tyrosine phosphorylation. Pulse-chase analysis of FGFR-1 biosynthesis suggests that the p125 and p100 proteins are the precursor forms of p145 FGFR-1alpha and p120 FGFR-1beta, respectively. Because ligand-chase analysis demonstrated that FGFR-1beta L6 myoblast transfectants exhibited a reduced efficiency of nuclear translocation of exogenous FGF-1 when compared with FGFR-1alpha transfectants, the intracellular trafficking of the FGFR-1alpha and FGFR-1beta isoforms was studied using an in vitro kinase assay to amplify immunoprecipitated FGFR-1. Indeed, the appearance of the FGFR-1alpha but not FGFR-1beta isoform in the nuclear fraction of L6 myoblast transfectants suggests that the distal Ig-like loop in FGFR-1alpha mediates the differential nuclear association of FGFR-1alpha as a structurally intact and functional tyrosine kinase. Further, the FGFR-1beta L6 myoblast transfectants but not the FGFR-1alpha myoblast transfectants exhibited a pronounced morphologic change in response to exogenous FGF-1. Because this phenotype change involves the induction of a rounded cellular shape, it is possible that the FGFR-1alpha and FGFR-1beta may ultimately exhibit differential trafficking to adhesion sites.
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PMID:The nuclear trafficking of extracellular fibroblast growth factor (FGF)-1 correlates with the perinuclear association of the FGF receptor-1alpha isoforms but not the FGF receptor-1beta isoforms. 866 99

Increased expression of alternatively spliced variants of the CD44 family of cell adhesion molecules has been associated with tumour metastasis. In the present study, expression of alternatively spliced variants of CD44 and their cellular distribution have been investigated in human colonic tumours and in the corresponding normal mucosa, in addition to benign adenomatous polyps. The expression of CD44 alternatively spliced variants has been correlated with tumour progression according to Dukes' histological stage. CD44 variant expression was determined by immunohistochemisty using monoclonal antibodies directed against specific CD44 variant domains together with RT-PCR analysis of CD44 variant mRNA expression in the same tissue specimens. We demonstrate that as well as being expressed in colonic tumour cells, the full range of CD44 variants, CD44v2-v10, are widely expressed in normal colonic crypt epithelium, predominantly in the crypt base. CD44v6, the epitope which is most commonly associated with tumour progression and metastasis, was not only expressed by many benign colonic tumours, but was expressed as frequently in normal basal crypt epithelium as in malignant colonic tumour cells, and surprisingly, was even absent from some metastatic colorectal tumours. Expression of none of the CD44 variant epitopes was found to be positively correlated with tumour progression or with colorectal tumour metastasis to the liver, results which are inconsistent with a role for CD44 variants as indicators of colonic cancer progression.
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PMID:Alternatively spliced variants of the cell adhesion molecule CD44 and tumour progression in colorectal cancer. 869 47

Members of the CD44 family of cell surface hyaluronate-binding proteins have been implicated in cell migration, cell-matrix interactions and tumor progression. To determine whether these proteins might play a role in the normal functions of Schwann cells and in their tumorigenesis, we examined the patterns of CD44 expression in Schwann cells from rat peripheral nerve, rat Schwann cell tumor lines, and human schwannomas. Normal rat spinal nerves and primary Schwann cell cultures expressed standard CD44 (CD44s) but not alternatively spliced variant isoforms. In contrast, rat Schwann cell tumor lines expressed both CD44s and a number of variants, including proteins containing sequences encoded by exon v6. Furthermore, we found that these cell lines bind hyaluronate, and that their cell surface hyaluronate binding correlates with CD44 expression. All of the human schwannomas also expressed CD44 variants, especially epitopes encoded by exon v5, the border between v7 and v8, and v9-10. These data indicate that Schwann cells normally express CD44s, that Schwann cell tumors express both CD44s and particular variants of CD44, and that CD44s and possibly variants of CD44 are involved in hyaluronate recognition by Schwann cell tumors.
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PMID:Schwann cell tumors express characteristic patterns of CD44 splice variants. 875 Jan 83

An alternatively spliced mRNA coding for a variant estrogen receptor (ER) missing exon 4 (ERdelta4) was detected in the breast tumor cell line MCF7 and meningioma tissue by using the reversed transcriptase PCR technique. The trans-activational properties of this mutant ER were assessed in embryo carcinoma P19EC and human choriocarcinoma JEG3 cells by co-transfection of the ERdelta4 expression vector with an oxytocin promoter construct containing an estrogen-responsive element. ERdelta4 did not trans-activate the oxytocin promoter in either a hormone-dependent or -independent manner. Co-transfection of ERdelta4 together with the wtER did not show any interference of ERdelta4 on the stimulation of the oxytocin promoter by the wtER. ERdelta4 was translated in vitro. Its capacity to bind estradiol, and the binding of the variant to a synthetic estrogen-responsive element were compared to those of the wild-type receptor. ERdelta4 did not bind to a synthetic estrogen-responsive element, nor did it bind estradiol. Hence, ERdelta4 appears to be a silent variant and we speculate that it is without any role in tumor progression.
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PMID:Functional analysis of an alternatively spliced estrogen receptor lacking exon 4 isolated from MCF-7 breast cancer cells and meningioma tissue. 939 58

An intensive search continues for reliable markers that would be clinically useful in the diagnosis of small tumors and in the evaluation of their predicted clinical outcome. One potential marker, extensively studied in human samples is the cell surface adhesion molecule CD44. The single CD44 gene codes for a large family of cell surface proteins by alternative splicing and severe abnormalities have been observed in the patterns of its expression in many types of human tumors using both protein and RNA-based analyses. These abnormalities are manifested by markedly increased levels of unusual transcripts and proteins in tumor cells compared to the corresponding normal tissues. Aberrant processing of immature CD44 transcripts has also been observed in tumor cells and this can lead to the inappropriate retention of introns and to the use of cryptic splice sites in the mRNA. Inappropriate expression patterns of the alternatively spliced exons have also been linked both to tumor progression and to metastatic potential. The clinical relevance of all these observations is demonstrated by the frequent detection of these abnormalities in samples from malignant tumors of many different organs and by their presence in pre-invasive and high risk pre-cancerous lesions. This article reviews the current information regarding the expression of the CD44 gene in tumor cells and its potential use as a marker in clinical evaluation. The overall conclusion is that with the use of the latest assay techniques and perhaps in combination with other molecular markers, analysis of CD44 expression can provide new and powerful assays for the detection of neoplastic disease.
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PMID:Clinical implications of anomalous CD44 gene expression in neoplasia. 963 41


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