Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q86TM3 (cage)
 29,987 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A low-molecular-weight acceptor of galactosyltransferase activity was detected in sera and effusions of patients with extensive maligant disease. This substance was purified to homogeneity from both human serum and effusion by using sequential charcoal/Celite and DEAE-cellulose column chromatography. The purified acceptor was shown to act as substrate for both purified normal and cancer-associated human galactosyltransferase (EC 2.4.1.22) isoenzymes, but had a higher affinity for the cancer-associated isoenzyme (Km = 20 microM) than for the normal isoenzyme (Km = 500 microM). The substrate was found to be a glycopeptide with mol.wt. approx. 3600 determined by polyacrylamide-gel chromatography. Carbohyydate analysis demonstrated only the presence of glucosamine and mannose. Amino acid analysis revealed that the peptide moiety consisted of eight different amino acids, including two residues of asparagine and one residue of serine, but no threonine. These structural data suggest that the acceptor is a fraction of an asparagine-glucosamine type of glycoprotein.
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PMID:Detection, purification and characterization of a human cancer-associated galactosyltransferase acceptor. 8 90

Many cancer-associated antigens are present on mucin glycoproteins. These include peripheral antigens such as sialyl Lea and sialyl Lex and core region carbohydrate antigens such as T, Tn, and Sialyl Tn. We have recently described an inhibitor of mucin glycosylation, benzyl-alpha-GalNAc. The purpose of this study was to determine its effect on expression of mucin carbohydrate antigens. HM7 colon cancer cells were treated for 2 days in culture with 2 mM benzyl-alpha-GalNAc. This treatment did not affect viability or doubling time, but inhibited synthesis of [3H]glucosamine-labeled mucins. There was also secretion of benzyl-oligosaccharides and a decrease in the proportion of long oligosaccharides on 3H-labeled mucins. Mucins were purified from spent media by gel filtration and assayed for binding of monoclonal antibodies and lectins. Mucins from benzyl-alpha-GalNAc-treated cells had increased binding of peanut agglutinin (specific for T antigen, Gal beta 3GalNAc) and Vicia villosa agglutinin B4 (specific for Tn antigen, GalNAc alpha-Thr/Ser), but decreased binding of monoclonal antibodies 19-9, SNH3, and 91.9H (specific for sialyl Lea, sialyl Lex, and sulfomucin, respectively). Treatment of the cells with benzyl-alpha-GalNAc also decreased their binding to E-selectin (ELAM-1), which recognizes sialyl Lea and sialyl Lex. Thus, benzyl-alpha-GalNAc treatment, which decreases the level of peripheral carbohydrate carbohydrate antigens on mucins with accumulation of core region antigens, may be useful in modifying the immunological and biological properties of colon cancer cells.
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PMID:Effect of benzyl-alpha-GalNAc, an inhibitor of mucin glycosylation, on cancer-associated antigens in human colon cancer cells. 128 81

The extracellular matrix adhesion molecule fibronectin exhibits different isoforms derived by alternative splicing as well as recently demonstrated variation in O-glycosylation. Although fibronectin is widely distributed in normal tissues, the individual isoforms have been found to show restricted tissue distribution and association with malignancies. The monoclonal antibody FDC-6 defines a cancer-associated de novo glycosylation of a specific threonine residue in the C-terminal region of the fibronectin molecule termed oncofetal fibronectin. Here we report an immunohistological study of oral squamous cell carcinomas (n = 33), premalignant lesions (n = 15), and normal oral mucosa (n = 10) using the FDC-6 antibody. A selective expression of the oncofetal fibronectin epitope was demonstrated in close relation to the invading carcinoma, whereas no staining was observed in premalignant lesions without epithelial dysplasia, or in normal epithelium. Furthermore, we attempted to identify additional carbohydrate-related epitopes distinguishing fibronectin of human hepatoma cell line HUH-7 from plasma fibronectin. No novel epitopes were identified, as all generated monoclonal antibodies lacking reactivity with plasma fibronectin showed the same specificity as FDC-6. Previous studies have indicated that the de novo glycosylation is induced by a novel transferase activity only found in fetal and carcinoma cell lines, placenta and hepatoma tissues. Here we provide further evidence that a purified UDP-GalNAc:peptide N-acetylgalactosaminyltransferase from normal bovine thymus and human placentae is incapable of utilizing the hexapeptide VTHPGY as a substrate. The results demonstrate that oncofetal fibronectin is highly associated with malignancy, and appears to be induced by expression of a unique glycosyltransferase or modification of the specificity of the normally expressed transferase.
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PMID:Cancer-associated changes in glycosylation of fibronectin. Immunohistological localization of oncofetal fibronectin defined by monoclonal antibodies. 138

Two monoclonal antibodies, MLS 102, which recognizes cancer-associated mucin antigens, and MLS 103, which recognizes normal mucin, were used to isolate, by immunoaffinity chromatography, the corresponding antigens from cell lysates and spent medium of a human colorectal carcinoma cell line, LS 180. The MLS 102 antigen contained serine, threonine, and proline as major amino acids. The carbohydrate chains of the MLS 102 antigen were composed of O-linked NeuAc alpha 2----6GalNAc (56%), N-acetylgalactosamine (25%), and longer oligosaccharide chains. The MLS 103 antigen differed from the MLS 102 antigen in both amino acid and carbohydrate composition. Most O-linked oligosaccharides of the MLS 103 antigen were longer than the disaccharide found in the MLS 102 antigen. Immunostaining of LS 180 cells using MLS 102 and MLS 103 revealed that the cells are heterogeneous with respect to the expression of the antigens.
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PMID:Characterization of mucin antigens recognized by monoclonal antibodies raised against human colon cancer cells. 198 95

Mucins synthesized in colonic cancer are known to be different from those in the normal colon; however, the biochemical differences between these mucins have not been defined. We have purified mucins from samples of nonneoplastic (normal) human colon and colon cancer and found that the carbohydrate content of the cancer-associated mucins is 48% of that in the normal colon, including significant reductions in galactose, N-acetylglucosamine, N-acetylgalactosamine, and fucose. By subjecting the mucins to alkaline degradation, we determined that there are 19% fewer oligosaccharide chains per milligram of cancer-associated colonic mucin than there are in mucins from normal colons. We also found a reduction in mean oligosaccharide chain length in cancer-associated mucin (5.83 carbohydrate residues per chain) compared with those derived from normal colons (10.2 residues). Total and individual amino acid contents were greater in cancer-associated mucins, with the exception of three amino acids (threonine, serine, and proline), two of which represent the O-linked glycosylation sites for glycoproteins. Thus, mucins are aberrantly glycosylated in colon cancer, both in terms of the number and mean chain length of the oligosaccharide moiety. Because of their relative abundance in colonic tissue, mucins appear to be useful molecular species in the study of the derangements in protein glycosylation that occur during neoplasia.
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PMID:The carbohydrate composition of mucin in colonic cancer. 232 10

The polymorphic epithelial mucin (PEM) appears to be the target molecule for many monoclonal antibodies (MAbs) which react with tumour-associated and epithelium-specific antigens. PEM contains a large domain made up of 20 amino-acid tandem repeats which are highly immunodominant as many of the antibodies reactive with this molecule recognize epitopes within this area. Using overlapping peptide octamers, we have precisely mapped the epitopes of 4 MAbs reactive with the tandem repeats including one, SM-3, which shows enhanced tumour specificity. We report that the core of the SM-3 epitope corresponds to the continuous amino acid sequence Pro-Asp-Thr-Arg-Pro. We also show that the epitopes recognized by 3 other antibodies, which show reactivity with normal and malignant tissues, map to within this area of the tandem repeat. However, none of these epitopes contain the proline found at the amino end of the SM-3 determinant. These results are consistent with the idea that, in the cancer-associated mucin, premature termination of the carbohydrate side-chains results in the exposure of the SM-3 epitope.
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PMID:A short sequence, within the amino acid tandem repeat of a cancer-associated mucin, contains immunodominant epitopes. 247 36

Mucin glycoproteins are major secretory products of the colon and contain O-linked oligosaccharides synthesized on a polypeptide backbone. The initial step in the synthesis of O-linked oligosaccharides is the addition of N-acetylgalactosamine to serine or threonine residues forming the Tn antigen. This substance can then receive additional carbohydrate residues such as sialic acid to form sialosyl-Tn antigen, or galactose to form T antigen. In the colon, the T antigen is an oncodevelopmental cancer-associated antigen but little is known about Tn and sialosyl-Tn expression. The present comparative immunohistochemical study was performed to analyze the expression of these antigens in fetal, normal adult, and malignant colorectal tissues with an aim toward elucidating whether Tn and sialosyl-Tn are also oncodevelopmental colon cancer-associated antigens and to gain insight into the earliest steps of mucin glycosylation in colonocytes. We used three reagents to detect Tn antigen (two monoclonal antibodies ETn1.01 and CU-1, and one lectin Vicia villosa), two reagents to detect sialosyl-Tn (monoclonal antibodies TKH2 and B72.3) and one to detect T antigen (monoclonal antibody AH9-16). Except for occasional reactivity with VVA and CU-1, cells of normal colonic mucosa did not express Tn, sialosyl-Tn, or T antigens. However, in the transitional mucosa immediately adjacent to cancer, all three antigens were expressed (ranging from 35 to 67% of cases depending upon the reagent). In colon cancers, the percentage of cases expressing each antigen were as follows: Tn 72-81%, sialosyl-Tn 93-96%, and T 71%. Unlike T antigen, which was preferentially expressed by moderately well- and well-differentiated adenocarcinomas, both Tn and sialosyl-Tn antigens were expressed by most histological subsets of colon cancers, including poorly differentiated adenocarcinomas and mucinous (colloid and signet ring cell type) carcinomas. The majority of cancers expressed both Tn and sialosyl-Tn, usually in association with T antigen. Only one cancer lacked all three antigens. Fetal colonic mucosal cells expressed all three antigens, particularly in goblet cell mucin. These results indicate that like T antigen, Tn and sialosyl-Tn are oncodevelopmental cancer-associated antigens in the colon. Moreover, Tn and sialosyl-Tn antigens appear to be useful markers of poorly differentiated adenocarcinomas and mucinous carcinomas: two histological subsets that often fail to express other cancer-associated antigens and that are often associated with a poor clinical outcome.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Expression of Tn, sialosyl-Tn, and T antigens in human colon cancer. 290 46

Mucin has been purified from nude mouse xenografts of SW1990 human pancreatic cancer cells. The mucin was eluted at the void volume of Sepharose CL-4B and was of density greater than 1.3 in CsCl gradients. The isolated mucin had a high content of threonine, serine, and proline, with 31% of the amino acid residues O-glycosylated. The average oligosaccharide composition was NeuAc1.8Fuc0.7Gal2.0GlcNAc1.7GalNAc1.4. Polyclonal rabbit antibodies prepared against the purified mucin recognized primarily mucin polypeptide, and there was extensive immunological cross-reaction between SW1990 pancreatic cancer mucin and LS174T colon cancer mucin. However, using carbohydrate-specific monoclonal antibodies, the two mucins were found to differ. SW1990 mucin had more Lewis, sialyl Lewis, and sialyl Lewis activity, while the colon cancer mucin had more sialyl T antigen. Since pancreatic mucins, whether from normal pancreas or pancreatic cancer, have not previously been well characterized, the availability of SW1990 pancreatic cancer mucin may be useful as a model for studying the expressing of organ-specific or cancer-associated antigens.
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PMID:Pancreatic cancer mucin from xenografts of SW1990 cells: isolation, characterization, and comparison to colon cancer mucin. 322 46

Previous studies from this laboratory have demonstrated that arylsulfatase B (ASB) is phosphorylated by a protein kinase, which is the first finding of phosphorylation in lysosomal hydrolases. The present study was undertaken to characterize the sites of phosphorylation in ASB from transplanted human lung cancer and from normal human tissues, and to identify type of tumor protein kinase responsible for the phosphorylation of ASB. When ASB purified from liver and placenta was phosphorylated in vitro by a cAMP-dependent protein kinase, it gave a single tryptic phosphopeptide (X) and phosphothreonine. On the other hand, the tumor ASB which had been phosphorylated in vivo demonstrated two phosphopeptides X and Y. Since the tumor ASB had been shown to be phosphorylated both at threonine and serine residues, phosphorylation at threonine residue of peptide X, which is phosphorylated by a cAMP-dependent protein kinase, will be cancer-associated. Through photoaffinity labeling with a labeled cAMP analogue to detect regulatory subunits of cAMP-dependent protein kinase subtypes, it was found that the cAMP-dependent protein kinase in the transplanted lung tumor was largely type II which can be ascribed to the appearance of highly phosphorylated ASB in the tumor.
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PMID:Protein phosphorylation of human lysosomal arylsulfatase B from normal and cancer tissues. 338 98

Many lysosomal hydrolases in cases of human cancer were found to be accompanied by acidic variant forms together with the major hydrolase components. Such variants were found to be phosphorylated not only at their carbohydrate moiety which contributes largely to their acidic property, but also at the protein moiety. We identified a cAMP-dependent protein kinase which is responsible for phosphorylation of arylsulfatase B. The protein kinase activity toward the sulfatase was considerably higher in transplanted lung cancer than in normal lung in the presence of cAMP. The B enzyme purified from normal human liver was found to contain 0.6mol of Pi/mol of B enzyme, and protein kinase treatment added a further 1.3mol Pi to give a single phosphopeptide (X) containing phosphothreonine. On the other hand, the B1 enzyme purified from transplanted human lung cancer which had been labeled in vivo with [32P] Pi revealed at least two phosphopeptides (X and Y). Assuming that the sulfatase from liver and lung cancer possesses the same number of available phosphorylation sites, phosphorylation of site X (Thr) which is available only by deliberate phosphorylation of the native, ordinary B enzyme, appears to be cancer-associated. Increased phosphorylation of the sulfatase resulted in a maximum 50% elevation in arylsulfatase activity, followed by a decrease in the activity upon overphosphorylation, using an artificial substrate.
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PMID:[Phosphorylation of lysosomal hydrolases in human cancer and its significance]. 360 35


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