Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0699790 (colon cancer)
 28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression of the MUC2 mucin has been demonstrated in normal gastrointestinal and respiratory epithelium and in carcinomas of the gastrointestinal and respiratory tracts, breast, ovary, and bladder using RNA probes and (or) monoclonal antibodies reactive with peptide epitopes on the 23 amino acid tandem repeat. Mouse monoclonal antibodies 4F1 and 3A2 were previously obtained by immunization with mucin derived from the LS174T colon cancer cell line and a KLH conjugate of a synthetic MUC2 VNTR peptide. These antibodies react with distinct epitopes on synthetic VNTR peptides and with normal and malignant epithelial tissues. In the present study, we examined the biosynthesis of MUC2 in LS174T colon cancer cells, using these antibodies to immunoprecipitate labelled mucin. A very high molecular mass protein was immunoprecipitated following 1 min pulse labelling with [3H]threonine and [3H]proline. A slight increase in molecular mass was observed over the next 16 min; however, unlike the MUC1 mucin, there was no large difference in apparent molecular mass between the MUC2 protein precursor and fully processed mucin using separation by SDS-PAGE. O-Glycosylation began within 1 h of synthesis of the protein core. Mucin secretion into the culture medium was detected in the 2nd hour following synthesis and was largely completed within 4 h of synthesis. Secreted mucin was far less reactive with these monoclonal antibodies than the precursor protein.
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PMID:Early steps in the biosynthesis of MUC2 epithelial mucin in colon cancer cells. 903 93

The human MUC2 gene maps to chromosome 11p15, where three additional mucin genes have been located, and encodes the most abundant gastrointestinal mucin normally expressed in the intestinal goblet cell lineage. However, in pathological conditions, including colorectal cancer, MUC2 can be abnormally expressed. Therefore, it is of considerable interest to understand the regulation of the MUC2 gene and how the mechanism is altered in colon cancer. Toward this goal, we have isolated a group of overlapping clones (contig) spanning 85 kilobases harboring the entire MUC2 locus, including sequences located upstream of the gene. Detection of two DNase I-hypersensitive sites in the 5' region of the MUC2 gene suggests the presence of DNA regulatory elements. To better characterize this region, we have sequenced 12 kilobases of the upstream region and analyzed it for functional activity by cloning portions of it into a luciferase reporter vector and assaying for promoter/enhancer activity using a transient transfection assay. A fragment from the AUG translational initiation codon +1 to -848 confers maximal transcriptional activity in several intestinal cell lines. Elements located further upstream exert a negative effect on the expression of the reporter gene when tested in conjunction with homologous or heterologous promoters. The same pattern of expression is observed when the MUC2/luciferase constructs are transfected into HeLa cells, which do not express the endogenous MUC2 gene. However, the level of activity in HeLa cells is at least an order of magnitude higher, suggesting that additional sequences singularly or in combination are responsible for the tissue- and cell lineage-specific expression of MUC2. Finally, we have identified an additional mucin-like gene (MUCX), located upstream of MUC2. We show that this MUCX gene, that is transcribed in opposite orientation to that of MUC2, is expressed with a pattern distinct from that of MUC2, yet similar to that of MUC5B and MUC6, two additional mucin genes located at chromosome 11p15. Recent information on the order of the mucin genes at chromosome 11p15 suggests that MUCX may be MUC6, one of the already identified mucin genes, or a novel one, yet to be fully characterized.
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PMID:Organization and regulatory aspects of the human intestinal mucin gene (MUC2) locus. 906 67

Trefoil peptides are a family of small proteins expressed by goblet cells that are secreted onto the apical gastrointestinal mucosal surface, where they are present in high concentrations. These peptides appear to both protect the epithelium and promote healing after injury. However, the factors regulating the expression and secretion of these proteins contributing to mucosal defense have not been characterized. To determine the mechanisms controlling production of trefoil peptides, the human colon cancer-derived model cell line HT-29 was exposed to a variety of potential secretagogues. Expression and secretion of human intestinal trefoil factor (hITF) as well as the intestinal apomucin MUC2 were assessed by Northern and Western blot analysis. Carbachol, an analog of acetylcholine, and the neuroendocrine peptides somatostatin and vasoactive intestinal polypeptide (VIP) stimulated increased expression of hITF mRNA within 5 min. These same factors stimulated parallel secretion of the hITF peptide, with maximal stimulation observed at concentrations ranging from 10(-6) M (carbachol and somatostatin) to 10(-7) M (VIP). Expression and secretion of hITF in response to carbachol, VIP, and somatostatin was independent of production of apomucin. hITF was not regulated by other neuroendocrine transmitters including histamine and substance P. Similarly, hITF expression and secretion was not modulated by peptide growth factors (epidermal growth factor, transforming growth factor-beta, and keratinocyte growth factor), cytokines [interleukin (IL)-1 beta, IL-2, IL-7, and IL-11], or arachidonic acid metabolites (prostaglandin E1/E2 and leukotriene B4). In conclusion, trefoil peptides appear to be integrated into mechanisms of mucosal defense and repair through the enteric neuroendocrine system and independent of the classical mucosal immune cytokine network.
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PMID:Trefoil peptide expression and secretion is regulated by neuropeptides and acetylcholine. 927 13

A monoclonal antibody (mAb; A10) raised against murine Ehrlich tumor cell surface carbohydrates was tested for reactivity with human normal and malignant tissues. A10 reacted strongly, with a high proportion of adenocarcinomas arising from colon and other tissues but not with breast carcinomas or other malignant tumors. Normal tissues were virtually A10 unreactive, except for the duct cells from breast and pancreas and some bronchial mucosae. Ultrastructural studies showed mAb A10 immunolabeling of both microvilli and mucin droplets in colon cancer cells but not in normal absorptive or globet cells. A10 reacted strongly with mucin-enriched fractions from colon cancer tissues and HT-29 xenografts but not from normal colon tissues. A10 epitope was carried on MUC1 derived from colon adenocarcinomas and probably on other mucin species, although not on MUC2 molecules. A10 epitope was resistant to exoglycosidases and periodate oxidation but sensitive to the Smith's degradation and beta-elimination, suggesting the involvement of O-linked carbohydrates in nonterminal reducing positions. A mucin-type glycosidic linkage was supported because of the lack of A10 reactivity with HT-29 cells grown with phenyl-N-acetyl-alpha-D-galactosaminide. Deglycosylation studies with trifluoromethanesulfonic acid pointed to the involvement of core mucin glycans in the A10 epitope. This epitope was resistant to protease, O- and N-glycanase treatments carried out on trifluoromethanesulfonic acid-deglycosylated mucins. Inhibition studies with core 1, core 2, core 3, and core 6 suggested the latter [GlcNAcbeta(1-6)GalNAc] as being involved in A10 epitope. Taken together, the present results point to A10 defining a core 6-related epitope on core mucin glycans expressed by colon cancer MUC1 not previously associated with human cancer.
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PMID:Human colon adenocarcinomas express a MUC1-associated novel carbohydrate epitope on core mucin glycans defined by a monoclonal antibody (A10) raised against murine Ehrlich tumor cells. 1007 Sep 64

On 18q, frequently deleted in late stage colorectal cancers, a gene, Deleted in Colon Cancer (DCC), has been identified and postulated to play a role as a tumor suppressor gene. DCC is retained in the majority of mucinous tumors, which produce high levels of mucins, and seems to be preferentially expressed in intestinal goblet cells. To investigate whether DCC is related to mucin expression and can modulate the transformed phenotype, we introduced a full-length DCC cDNA into HT29 cells, which can be induced in vitro to express MUC2, the gene that encodes the major colonic mucin. Expression of DCC did not modulate constitutive or induced expression of MUC2, nor did DCC induce a mature goblet cell phenotype. However, HT29 clones expressing high and low levels of DCC protein showed a significant decrease in cell proliferation and tumorigenicity. Furthermore, increased shedding and an elevated rate of spontaneous apoptosis were associated with higher levels of expression of DCC. In summary, while restoration of DCC expression in a human colon carcinoma cell line did not influence expression of differentiation markers, DCC expression did affect the growth and tumorigenic properties of the cells suggesting that DCC can modulate the malignant phenotype of colon cancer.
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PMID:Altered phenotype of HT29 colonic adenocarcinoma cells following expression of the DCC gene. 1035 3

We have previously reported that HT29 human colon cancer cells selected by adaptation to 5-fluorouracil (5FU) (HT29-5FU cells) express increased levels of a major intestinal mucin MUC2 mRNA compared with parental HT29 cells. In this study, we examined in detail the changes in synthesis and secretion of mucin that occur in these cells and accompanying changes in the expression of cancer associated mucin related carbohydrate antigens and cell lineage associated biochemical markers. We further investigated their relationship to biological properties of cells. Northern blot analysis revealed a markedly increased level of MUC2 mRNA but no significant change in the mRNA levels of other mucins in HT29-5FU cells compared with parental HT29 cells. Labeling with radiolabeled precursors demonstrated increased synthesis and secretion of mucin glycoproteins by HT29-5FU cells. Immunoblot analysis showed a higher expression of mucin associated carbohydrate antigens such as T, Tn, sialyl Tn, sialyl Lea, sialyl Lex and non-O-acetylated sialic acid concomitant with significant increases in the expression of goblet cell lineage marker, MUC2 apomucin and a panepithelial cell marker, carcinoembryonic antigen. HT29-5FU cells showed significantly higher adhesion to E-selectin and to matrigel and in vitro invasive properties and significantly increased liver colonization capacity in nude mice following splenic vein injection. Nude mouse xenograft tumors produced by HT29-5FU cells showed a greater degree of differentiation, consisting of mucin secreting glands than those produced by parental HT29 cells. These results indicate that predominantly colonic type mucin, MUC2, has been selectively induced in HT29-5FU cells and that altered regulation of mucin genes associated with altered synthesis and secretion of mucin glycoproteins and the degree of differentiation in cancer cells may be responsible for the altered biological properties of these cells.
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PMID:Biological properties and expression of mucins in 5-fluorouracil resistant HT29 human colon cancer cells. 1085 31

Phorbol esters such as phorbol 12-myristate 13-acetate (PMA) have been reported to modulate diverse cellular responses through signal transduction pathways including the protein kinase C (PKC) pathway. In the present study, we sought to determine the effect of PMA on mucin gene expression and on the biological properties of a human colon cancer cell line, HM3. The cells were treated for 8 and 24 h with various concentrations of PMA and total RNA was extracted and Northern and slot blot analyses were carried out using MUC2, MUC3 and MUC5AC mucin cDNA probes to assess the steady state levels of mRNA. Spent media were collected and the level of cancer associated carbohydrate antigens (T, Tn, sialyl Tn, sialyl Lex, and sialyl Lea) and matrix-degrading metalloproteinase (MMPs) activity were examined. Trypsinized cells were used for assessing in vitro invasion, motility and adhesion to matrigel. Our results showed that PMA caused upregulation of steady state mRNA levels of MUC2, MUC3 and MUC5AC which was inhibited after treatment with protein synthesis inhibitors. Calphostin C, a highly specific inhibitor of protein kinase C significantly inhibited the PMA induced induction of mRNA levels of MUC2, MUC3, and MUC5AC. The levels of all cancer-associated mucin carbohydrate antigens examined in the media were increased by PMA treatment. PMA also caused an increase in MMPs activity and in in vitro invasion and motility properties, but did not affect adhesion of HM3 cells to matrigel. Thus, PMA caused a significant increase in the expression of all three mucin genes through signaling pathways involving protein kinase C and increased secretion of mucin associated carbohydrate antigens. These changes were associated with increases in MMP activity as well as by increases in the invasive and motility properties of HM3 colon cancer cells. These data suggest that protein kinase C signaling pathways may be involved in mucin gene regulation and in modulating the invasive and metastatic properties of colon cancer cells.
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PMID:Phorbol 12-myristate 13-acetate induces alteration in mucin gene expression and biological properties of colon cancer cells. 1093 88

Modulation of mucin gene expression is an important component both in the early steps of colon cancer development and in later tumor progression. Previous work from our laboratory and others has suggested that the Sp family of transcription factors may play an important role in the regulation of the human MUC2 gene. To determine whether this was an essential element, we extended our work to the cloning and analysis of 3.5 kb of the 5'-flanking region of the mouse Muc2 (mMuc2) gene. Comparative analysis between the mouse and human MUC2 promoter regions has identified a strong sequence homology between the mouse and human genes, including the presence of GC-rich boxes, the location and composition of which are maintained in the mouse and human genes. We show that these GC boxes are binding sites for Sp-family transcription factors and are functionally important since mithramycin, an inhibitor of Sp1/Sp3 binding, blocks MUC2 gene expression in HT29 cells. Furthermore, by a combination of gel shift analysis and site-directed mutagenesis, we have identified the relative contribution of individual GC boxes, and of the factors they bind, to the regulation of the mouse Muc2 promoter, which appears to be different in the mouse and human genes. Finally, we demonstrate by overexpressing Sp1 and Sp3 that the functional difference between the proximal promoter region of the MUC2 gene in the two species is not attributable to differential ability of this region to bind members of the Sp family of transcription factors, but rather to the different anatomy of the individual GC boxes in the mouse and human proximal promoters.
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PMID:The Sp family of transcription factors in the regulation of the human and mouse MUC2 gene promoters. 1121 51

The alteration of the mucin profile have been known to play a role in colorectal carcinogenesis. MUC1 is up-regulated and MUC2 is down-regulated in colorectalcarcinomas. Overexpression of p53 is frequently noted in colorectal carcinomas with deep invasion or lymph node metastasis. However, there have been few reports about the association between MUC1, MUC2, and p53 expression with respect to the metastatic potential. This study was aimed to investigate the relationship of MUC1, MUC2, and protein p53 expressions with clinicopathological factors in colorectal carcinomas. Expressions of MUC1, MUC2, and p53 protein were examined immunohistochemically. Of total 97 cancers, 44 (45%) were MUC1 positive, 39 (40%) were MUC2 positive and 58 (59%) showed a p53 overexpression. Coexpression of MUC1 with p53 and dual expression of MUC1 with MUC2 were associated with a higher frequency of lymph node metastasis (p<0.05). The right colon showed a higher MUC1 positivity and frequent lymph node metastasis than the left colon (p<0.05). These results suggest that the coexpression of MUC 1 with p53 or MUC2 are involved in regional lymph node metastasis in colorectal carcinomas. The high expression of MUC1 in the right colon cancer was revealed to relate with lymph node metastasis.
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PMID:Coexpression of MUC1 with p53 or MUC2 correlates with lymph node metastasis in colorectal carcinomas. 1185 May 85

MUC2 is a secretory mucin normally expressed by goblet cells of the intestinal epithelium. It is overexpressed in mucinous type colorectal cancers but down-regulated in colorectal adenocarcinoma. Phorbol 12-myristate 13-acetate (PMA) treatment of colon cancer cell lines increases MUC2 expression, so we have undertaken a detailed analysis of the effects of PMA on the promoter activity of the 5'-flanking region of the MUC2 gene using stably and transiently transfected promoter reporter vectors. Protein kinase C inhibitors (bisindolylmaleimide, calphostin C) and inhibitors of mitogen-activated protein/extracellular signal regulated kinase kinase (MEK) (PD98059 and U0126) suppressed up-regulation of MUC2. Src tyrosine kinase inhibitor PP2, a protein kinase A inhibitor (KT5720), and a p38 inhibitor (SB 203580) did not affect transcription. Western blotting and reverse transcription-PCR analysis confirmed these results. In addition, co-transfections with mutants of Ras, Raf, and MEK showed that the induction of MUC2 promoter activity by PMA required these three signaling proteins. Our results demonstrate that PMA activates protein kinase C, stimulating MAP kinase through a Ras- and Raf-dependent mechanism. An important role for nuclear factor kappaB (NF-kappaB) was also demonstrated using the inhibitor caffeic acid phenethyl ester and electrophoretic mobility shift assays. Such identification of pathways involved in MUC2 up-regulation by PMA in the HM3 colon cancer cell line may serve as a model for the effects of cytokines and growth factors, which regulate MUC2 expression during the progression of colorectal cancer.
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PMID:Phorbol 12-myristate 13-acetate up-regulates the transcription of MUC2 intestinal mucin via Ras, ERK, and NF-kappa B. 1207 18


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