UMLS:C0699790 - FACTA Search

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

Query: UMLS:C0699790 (colon cancer)
28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Correlation between expression of the mdr-1 genes (a and b) at the mRNA and protein level and volume-activation of chloride-channels was studied in rat colon cancer CC531 cells by means of RT-PCR, Western blotting and patch clamp, respectively. Three different kinds of cell lines were used: CC531-PAR, CC531-COL and CC531-REV. At the mRNA level, the parental cell line CC531-PAR showed significantly less mdr-1a expression in comparison with CC531-COL, a drug-resistant cell line induced from the parental CC531 cells by growth in the presence of colchicin. The third cell line, CC531-REV, was a spontaneous revertant of the drug-resistant cell line to a drug-sensitive one, but with a maintained level of mdr-1a mRNA. In none of the three cell lines, mdr-1b mRNA could be detected. At the protein level, a clear difference in mdr1 expression between CC531-PAR/REV and CC531-COL was observed. Although the amount of mdr-1a mRNA detected in CC531-REV was comparable to that found in CC531-COL, the amount of mdr-1 encoded protein in CC531-REV was remarkably reduced. In all three cell types, cell swelling activated chloride-currents which could be blocked by NPPB.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Lack of correlation between mdr-1 expression and volume-activation of cloride-currents in rat colon cancer cells. 767 40

The plasminogen activator urokinase promotes tumor invasion by converting plasminogen into plasmin, which degrades several extracellular matrix components. Urokinase can bind to a specific cell surface receptor, which leads to accelerated plasmin production. While there is good evidence indicating a role for this binding site in tumor invasion/metastasis, there is little information concerning the regulation of urokinase receptor expression in invasive cancer. To address this question a series of colon cancer cell lines, which demonstrate either a high or low ability to invade an extracellular matrix-coated porous filter, was characterized for receptor expression at the transcriptional and post-transcriptional levels. The invasive cell lines possessed 10-fold more receptors than their non-invasive counterparts as shown by cross-linking experiments and by Western blotting. Northern blotting indicated that this disparity in receptor number could be largely accounted for by a different amount of steady-state mRNA encoding the binding site. However, neither gene amplification nor enhanced mRNA stability could account for the augmented receptor protein observed for the invasive colon cancer cell types. In contrast, nuclear run-on experiments with representative cell lines revealed that the 10-fold difference in receptor display between the invasive-competent and invasive-deficient cells could be largely accounted for by differences in transcription rates. Transcription of the u-PAR gene in the receptor-deficient GEO cells, but not in the receptor-rich RKO cells, could be augmented by protein kinase C stimulation. These findings provide a clear rationale for studies to determine if the urokinase receptor promoter in invasive colon cancer is activated in cis or in trans.
...
PMID:Transcriptional activation of the urokinase receptor gene in invasive colon cancer. 807 48

The urokinase-type plasminogen activator receptor (u-PAR) facilitates extracellular matrix proteolysis by accelerating plasmin formation at the cell surface. The present study was undertaken to identify elements in the u-PAR promoter required for the elevated expression of this binding site. Toward this end, we used two cultured colon cancer cell lines; one (RKO) has a transcriptionally activated u-PAR gene, and the other (GEO) overexpresses the receptor only after phorbol ester treatment. A chloramphenicol acetyltransferase (CAT) reporter driven by 398 nucleotides of 5' regulatory sequence of the u-PAR gene was strongly activated in the RKO cells, which displays approximately 3 x 10(5) receptors/cell. A region of this promoter between -197 and -8 was required for optimal expression, as indicated using a CAT reporter driven by 5' deleted fragments. DNase I footprinting revealed three protected regions (I, -190 to -171; II, -148 to -124; and III, -99 to -70) in this part of the promoter. Mutation of an AP-1 binding site at -184 within region I reduced activation of the promoter by 85%. Deletion of either region II or III also reduced promoter activity by over 60%. An oligonucleotide spanning the AP-1 motif at -184 bound, specifically, nuclear factors from RKO cells, and antibodies specific for Jun-D, c-Jun, or Fra-1 proteins supershifted the complex indicating the presence of these proteins. The amount of these factors was reduced in GEO cells in which the u-PAR gene is only weakly transcriptionally activated. Expression of a vector encoding a wild-type Jun-D cDNA increased u-PAR promoter activity in GEO cells. Conversely, transfection of RKO cells with a transactivation domain-lacking Jun-D expression construct resulted in a dose-dependent decrease in u-PAR promoter activity. Treatment of GEO cells with phorbol ester increased u-PAR mRNA and the activity of a CAT reporter driven by the wild-type but not the AP-1 (-184)-mutated u-PAR promoter, and this was associated with a strong induction in the amount of Jun-D, c-Jun, and c-Fos. Methylation interference studies using a fragment of the u-PAR promoter (spanning -201 to -150) bound with nuclear extracted proteins from RKO cells, and phorbol 12-myristate 13-acetate-treated and -untreated GEO cells showed that the contact points corresponded to the AP-1 binding site at -184. Thus, the elevated expression of u-PAR in RKO cells, which constitutively produces this binding site, as well as in phorbol 12-myristate 13-acetate-stimulated GEO cells requires an AP-1 motif located 184 bp upstream of the transcriptional start site.
...
PMID:Requirement of an upstream AP-1 motif for the constitutive and phorbol ester-inducible expression of the urokinase-type plasminogen activator receptor gene. 879 12

MMP-9 (gelatinase B) and urokinase-type plasminogen activator receptor (u-PAR), which are involved in cancer cell invasion and metastasis, are reported to be predominantly expressed by immune/inflammatory cells in human colorectal cancers. To investigate their significance in cancer progression, we morphometrically analyzed the tissue expression of MMP-9 and u-PAR among different stages of colorectal cancer. The numbers of MMP-9- and u-PAR-positive cells along the invasive margin were significantly smaller in cases with liver metastasis than in cases without liver metastasis, and were also smaller in cases with an infiltrating margin than in cases with an expanding margin. Both variables were larger in colon cancer cases with conspicuous lymphocytic infiltration. These results indicated that the degree of tissue expression of MMP-9 and u-PAR by host cells is inversely associated with liver metastasis and an infiltrating growth pattern in human colorectal cancers. Essentially the same results were obtained for the number of macrophages distributed along the invasive margin. We also found that the expression pattern of MMP-9 was similar to that of MMP-8 (polymorphonuclear leukocyte collagenase). These data are consistent with clinicopathologic studies of host cells. Therefore, our data suggest a dual role of MMP-9 and u-PAR expression in colon cancer tissue; i.e., not only are these proteinases cancer-promoting factors, but also they are related to the host defensive mechanism when they are expressed by host cells.
...
PMID:Stromal expression of MMP-9 and urokinase receptor is inversely associated with liver metastasis and with infiltrating growth in human colorectal cancer: a novel approach from immune/inflammatory aspect. 904 99

The urokinase-type plasminogen activator receptor (u-PAR) facilitates extracellular matrix degradation in part by accelerating plasmin formation at the cell surface. We previously reported that u-PAR expression is elevated in colon cancer cell lines characterized by their in vitro invasive capacity. Since, u-PAR expression is increased by a variety of growth factors, which signal through the extracellular signal-regulated kinases 1 and 2 (ERK1/ERK2), we determined if these mitogen-activated protein kinases (MAPKs) regulate u-PAR expression in two cultured colon cancer cell lines. An in-gel kinase assay showed that ERK1 activity was considerably higher in RKO cells, which display > or = 10(5) receptors/cell, than the GEO cells which have approximately 10(4) urokinase receptors per cell. The expression of either an ERK-inactivating phosphatase (CL100), or a kinase-defective ERK1, decreased the activity of a u-PAR promoter-driven CAT reporter in RKO cells. Immune complex kinase assays indicated that the constitutive ERK1 activity in RKO cells was largely a result of an activated MEK1. Further, treatment of RKO cells with a specific inhibitor (PD 098059) of MEK1 activation, which diminished ERK1 activity, reduced the amount of urokinase specifically bound to the cell surface and this was associated with reduced laminin degradation. The expression of a dominant negative c-Raf-1 also reduced u-PAR promoter activity suggesting that MEK1 activation involved an activator at, or upstream, of this serine-threonine kinase. Transfection of the u-PAR-deficient GEO cells with a constitutively activated MEK1 expression construct up-regulated u-PAR promoter activity. Similarly treatment of GEO cells with a phosphatase inhibitor (sodium vanadate) caused a dose-dependent increase in ERK1 activity which paralleled increased cell surface binding of urokinase. Taken together, these data suggest that elevated u-PAR expression, in at least a sub-population of colon cancer, is partly a consequence of a constitutively activated ERK-1-dependent signaling cascade.
...
PMID:Elevated urokinase-type plasminogen activator receptor expression in a colon cancer cell line is due to a constitutively activated extracellular signal-regulated kinase-1-dependent signaling cascade. 919 Oct 56

Since c-src overexpression increases colonic cell invasiveness and because both Src activity and urokinase receptor protein are elevated in invasive colon cancers, the present study was undertaken: 1) to determine if a constitutively active Src regulates urokinase receptor expression and 2) to identify required cis-elements and trans-acting factors. SW480 colon cancer cells transfected with an expression plasmid (c-srcY527F) encoding a constitutively active Src protein manifested increased urokinase receptor gene expression and Src activity. Treatment of the src transfectants with a Src-inhibitor (PD173955) reduced urokinase receptor protein levels and laminin degradation. Inasmuch as we recently implicated an upstream region of the urokinase receptor promoter (-152/-135) in constitutive urokinase receptor expression, we determined its role for the induction by src. Whereas the activity of a CAT reporter driven by this region was stimulated by c-srcY527F, the u-PAR promoter mutated at the Sp1-binding motif in the -152/-135 region was not. Nuclear extracts from the src transfectants demonstrated increased Sp1 binding to region -152/-135 compared with those from SW480 cells. Finally, endogenous urokinase receptor protein amounts in 10 colon cancers and corresponding normal colon correlated with Src specific activity. These data suggest that urokinase receptor gene expression is regulated by Src partly via increased Sp1 binding.
...
PMID:Transcriptional induction of the urokinase receptor gene by a constitutively active Src. Requirement of an upstream motif (-152/-135) bound with Sp1. 1037 50

The urokinase-receptor (u-PAR) is a central molecule of invasion and metastasis promoting plasminogen-dependent extracellular matrix degradation in diverse carcinoma types such as gastric or colon cancer. Overexpression of u-PAR has been reported to occur mainly at the transcriptional level in malignant cells, and has been shown to indicate a poor clinical prognosis of cancer patients. This review will give an overview on experimental findings on u-PAR and its function, molecular mechanisms of its regulation, and its impact for future clinical decision planning and potential therapeutic concepts.
...
PMID:Molecular regulation of urokinase-receptor gene expression as one potential concept for molecular staging and therapy. 1279 Mar 18

The urokinase-type plasminogen activator receptor (u-PAR) plays a central role in cell migration, growth, and invasion and is regulated, in part, transcriptionally. In mice, u-PAR expression is restricted to a few tissues, one of which is the colon. We therefore screened a colon expression library for regulators of u-PAR promoter activity and identified a zinc finger protein bearing consensus sequences to the Kruppel-like family of transcription factors and showing partial homology with one of the members, KLF4. Like u-PAR, KLF4 expression is predominant in the luminal surface epithelial cells of the colonic crypt, and we hypothesized that u-PAR synthesis in these cells is directed by this transcription factor. Colon cells from KLF4 null mice showed a dramatic reduction in u-PAR protein compared with wild-type mice. Conversely, KLF4 expression in HCT116 colon cancer cells increased the amount of u-PAR protein/mRNA. Transient transfection of KLF4 with a reporter driven by 5'-deleted u-PAR promoter fragments indicated the requirement of the proximal 200 base pairs for optimal expression. Mobility-shifting experiments demonstrated binding of KLF4 to multiple regions of the u-PAR promoter (-154/-128, -105/-71, and -51/-24), and chromatin immunoprecipitation assays confirmed the binding of KLF4 to the endogenous promoter. Deletion of the -144/-123 promoter region diminished but did not eliminate the ability of KLF4 to transactivate the u-PAR promoter, suggesting cooperativity of these binding sites with respect to activation of gene expression. In conclusion, we have identified KLF4 as a novel regulator of u-PAR expression that drives the synthesis of u-PAR in the luminal surface epithelial cells of the colon.
...
PMID:The Kruppel-like KLF4 transcription factor, a novel regulator of urokinase receptor expression, drives synthesis of this binding site in colonic crypt luminal surface epithelial cells. 1503 Dec 82

Colon cancer progression is associated with the activation of protein kinase C (PKC), the downregulation of functional E-cadherin and an increased expression of the serine protease urokinase (u-PA) and its receptor (u-PAR). HT29-M6 intestinal epithelial cells represent an in vitro model to study colon cancer progression. These cells are induced to scatter and to invade by phorbol esters. Using proteolytic and cell signaling inhibitors, we show that HT29-M6 cells require plasminogen for the acquisition of the scattering response to PMA. Our results indicate that, prior to inducing a state of competency for plasminogen-dependent scattering, PMA triggers an ordered succession of events where upregulation of the activity of u-PA precedes proteolysis of u-PAR and active degradation of the extracellular matrix (ECM). These events poise HT29-M6 cells to a scatter-competent state that allows the subsequent localized proteolytic activation of plasminogen to plasmin, required for the execution of scattering. Finally, we show that, in addition to its enzymatic activity directed at the degradation of ECM, plasmin generates an intracellular signal resulting in the phosphorylation of ERK 1/2. For a full motogenic activity, plasmin requires this signal since the use of a MEK inhibitor (PD98059) specifically blocks the plasmin-dependent phase of cell scattering. Our observations suggest that plasmin exerts a dual role in PMA-induced scattering of HT29-M6 cells, one directed extracellularly to promote proteolysis of the ECM and one directed to generate intracellular signaling.
...
PMID:Requirement of the enzymatic and signaling activities of plasmin for phorbol-ester-induced scattering of colon cancer cells. 1663 Nov 61

The transcriptionally regulated urokinase-type plasminogen activator receptor (u-PAR) contributes to cancer progression. Although previous studies have identified multiple 5' regulatory elements, these cis motifs cannot fully account for u-PAR expression prompting a search for hitherto uncharacterized regulatory elements. DNase I hypersensitivity and chromatin immunoprecipitation assays using u-PAR-expressing colon cancer cells indicated a hypersensitive region (+665/+2068) in intron 1 enriched with acetylated histone 3 (H3) and H3 methylated at lysine 4, markers of regulatory regions. The +665/+2068 region increased transcription from a u-PAR-promoter in an orientation- and distance-independent manner fulfilling the criteria of an enhancer. Optimal stimulation of the u-PAR promoter by phorbol ester required this enhancer. Systematic truncations combined with DNase I footprinting revealed two protected regions (+1060/+1099 and +1123/+1134) with deletion of the latter practically abolishing enhancer activity. The +1123/+1134 region harbored non-consensus activator protein-1 and Ets1 binding sites bound with c-Jun (and/or the related JunD/JunB) and c-Fos (and/or the related FosB/Fra-1/Fra-2) as revealed with chromatin immunoprecipitation. Further, nuclear extract from resected colon cancers showed elevated protein binding to a +1123/+1134-spanning probe coordinate with elevated u-PAR protein. Thus, we have defined a novel intragenic enhancer in the u-PAR gene required for constitutive and inducible expression.
...
PMID:Identification of an histone H3 acetylated/K4-methylated-bound intragenic enhancer regulatory for urokinase receptor expression. 1700 7

1 2 Next >>