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)

The expression of cancer-associated antigens, Tn and sialyl Tn, was examined using monoclonal antibodies, MLS 128 and MLS 102, recognizing these two antigens, respectively. A cell lysate from a human carcinoma cell line, LS 180 cells, was analysed by Western blotting using these two antibodies. Three glycoprotein bands were discernible with each antibody, of which two, corresponding to 250 and 210 kDa, were reactive with both the antibodies. LS 180 cells were metabolically labelled with 3H-glucosamine and then the lysate from these cells was applied to two immunoaffinity columns. Sixty-five per cent of the Tn antigenic glycoproteins, based on radioactivity, bound to the MLS 102 affinity column. On the other hand, 45% of the sialyl Tn antigenic glycoproteins bound to the MLS 128 affinity column. These results indicate that some Tn and sialyl Tn antigens were expressed on the same polypeptide chains. The presence of non-sialylated GalNAc residues on the polypeptide chain with many Sia-GalNAc residues appears to be due to the incapability of three consecutive moieties of GalNAc-Ser/Thr to accept sialic acid.
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PMID:Coexpression of cancer-associated carbohydrate antigens, Tn and sialyl Tn. 784 2

Phospholipase A2 [EC 3.1.1.4] treatment of pig kidney Na+,K(+)-ATPase [EC 3.6.1.3] labeled with fluorescence probes at the alpha-chain reduced the extent of the fluorescence intensity change of an N-[p-(2-benzimidazolyl)phenyl]maleimide (BIPM) probe at Cys-964 to below one-third of the control level accompanying the accumulation of phosphoenzymes. However, it only induced a slight decrease in that of a fluorescence isothiocyanate (FITC) probe at Lys-501 with a large decrease in the rate of change. The addition of phosphatidylserine (PS) or phosphatidylinositol (PI) to the phospholipase-treated BIPM-FITC-labeled enzyme increased the rate of the FITC fluorescence change. Phospholipase treatment of the BIPM-enzyme greatly reduced the Na+,K(+)-ATPase activity. The addition of PS or PI to the treated enzyme induced reactivation. These data and others suggest that Cys-964 and Glu-953 (Rb+ protectable dicyclohexyl carbodiimide binding site) are located in the vicinity of the surface area of the enzyme where hydrocarbon chains of phospholipids are present, and conserved H-bonding amino acids, Thr-955 and Ser-962, are located rather near the center of a domain forming a cation binding route or cage with other hydrophobic transmembrane segments. These data may indicate that the interaction between the BIPM probe and the hydrocarbon chains of phospholipids changes in such a way as to sense the change in the binding state of various ligands accompanying the sequential appearance of reaction intermediates of the enzyme.
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PMID:Different susceptibility to phospholipase A2 treatment of the fluorescence intensity changes in the vicinity of Cys-964 and Lys-501 in the alpha-chain of probe-labeled Na+,K(+)-ATPase. 805 57

Translation of an immune response into therapy is probably the toughest task in designing vaccines for cancer due to the heterogeneity of the cell surface antigens which display tremendous variations in glycoforms. Consequently, a small segment (antigen) of cancer-associated mucin, in spite of generating antigen-specific immune responses, may be limited in therapeutic value. It is important that the synthetic segment resembles the native cancer-associated mucin in both structure and conformation. Synthetic cancer associated mucin derived 16 amino acid peptide GVTSAPDTRPAPGSTA and its partially glycosylated forms have demonstrated specific binding to two monoclonal antibodies, B27.29 and BCP8, raised against the native cancer associated mucin, MUC-1 and a MUC-1 derived synthetic peptide, respectively. In spite of the structural similarities at the core peptide level of both glycosylated and unglycosylated peptides, it appears that partial glycosylation does not inhibit and even slightly enhances binding to the MAb B27.29 indicating that the glycosylated synthetic peptide more closely resembles the native mucin epitope recognized by MAb B27.29. From molecular dynamic simulations using NMR derived distance constraints, both glycosylated and unglycosylated peptides have shown a type 1 beta turn involving the same amino acids in both glycosylated and unglycosylated peptides. The alpha GalNAc attached to the threonine (T3) and serine (S4) in the 16 amino acid sequence has not imposed any conformational changes to the peptide backbone nor has offered severe steric resistance to the binding of either antibody to the glycopeptides as indicated by hapten inhibition studies. Nevertheless, all peptides have displayed glycosylation dependent specificities in binding to these antibodies, i.e. the glycosylated peptides demonstrated relative higher affinities to the native mucin antibody B27.29 while the unglycosylated peptide is more specific to the MAb BCP8. Immune responses generated by these synthetic glycopeptides are highly specific in recognizing the native cancer associated mucin.
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PMID:Structurally defined synthetic cancer vaccines: analysis of structure, glycosylation and recognition of cancer associated mucin, MUC-1 derived peptides. 859 49

A pseudotetrapeptide analogue of the pyrokinin/PBAN or FXPRLamide family (Cbe-Thr-Pro-Agr-Leu-NH2; Cbe = 2-o-carboranylethanoyl-), in which the phenyl ring of the Phe side chain is replaced with the hydrophobic cage-like o-carborane moiety, was synthesized and found to be 10-fold more potent than cockroach leucopyrokinin on an isolated cockroach hindgut bioassay system. In contrast with the naturally occurring peptide, the myostimulatory activity could not be immediately reversed following a saline rinse, providing evidence that the pseudopeptide analogue binds very strongly to the receptor. Once the analogue reaches the receptor, strong receptor binding characteristics may allow it to avoid inactivation by hemolymph peptidases. Although it has an eightfold smaller sequence than the endogenous 33-membered pheromone biosynthesis activating neuropeptide (PBAN), the carboranyl analogue is 10-fold more potent in an in vivo pheromonotropic bioassay of the female tobacco budworm moth Heliothis virescens, demonstrating that the small, C-terminal pentapeptide pyrokinin core analogue contains all the structural information necessary to fully activate pyrokinin receptors. In contrast with PBAN, the amphiphylic carboranyl analogue elicits pheromone production following topical application in aqueous solution to the lateral abdominal surface of H. virescens, providing a noninvasive means of inducing pheromone production in moths. The analogue can potentially serve as a useful tool to insect researchers studying, and/or attempting to disrupt, physiological processes regulated by pyrokinin-like neuropeptides in insects. A possible role for this and related pyrokinin analogues in future pest insect management strategies is briefly discussed.
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PMID:Potent pheromonotropic/myotropic activity of a carboranyl pseudotetrapeptide analogue of the insect pyrokinin/PBAN neuropeptide family administered via injection or topical application. 884 62

Sialyl-Tn antigen (SAalpha2-6 GalNAc alpha-Ser/Thr) is expressed as a cancer-associated antigen on the surface of cancer cells and its expression correlates with a poor prognosis in patients with colorectal and other adenocarcinomas. To understand the enzymatic basis of sialyl-Tn (STn) antigen expression, we used two clonal cell lines, LSB and LSC, derived from LS174T human colonic cancer cells. LSC cells express only the truncated carbohydrate antigen Tn (GalNAc alpha-Ser/Thr) and sialyl-Tn on their mucin molecules, whereas LSB cells express elongated oligosaccharide chains. Both cell lines demonstrated similar activities of glycosyltransferases involved in the biosynthesis of elongated and terminal structures of complex O-glycans. However, LSC cells were unable to synthesize core 1 (Gal beta1-3GalNAc-) because the ubiquitous enzyme activity of UDP-Gal:GalNAc-R beta3-Gal-transferase (core 1 beta3-Gal-transferase) was lacking. Core 1 beta3-Gal-transferase could not be reactivated in LSC cells by treatment with sodium butyrate or by in vivo growth of LSC cells in nude mice. In contrast, LSB cells were able to synthesize and process core 1 and core 2 (GlcNAc beta1-6 (Gal beta1-3) GalNAc-). LSC cells represent the first example of a non-hematopoietic cell line which lacks core 1 beta3-Gal-transferase activity. The lack of core 1 beta3-Gal-transferase in LSC cells explains why they are incapable of forming the common mucin O-glycan core structures and are committed to synthesizing the short Tn and STn oligosaccharides. These findings suggest that the activity of core 1 beta3-Gal-transferase is an important determinant of the STn phenotype of colon cancer cells.
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PMID:Enzymatic basis for sialyl-Tn expression in human colon cancer cells. 988 66

The insulin-like growth factor II/mannose 6-phosphate receptor (IGF2R) carries out multiple regulatory and transport functions, and disruption of IGF2R function has been implicated as a mechanism to increase cell proliferation. Several missense IGF2R mutations have been identified in human cancers, including the following amino acid substitutions occurring in the extracytoplasmic domain of the receptor: Cys-1262 --> Ser, Gln-1445 --> His, Gly-1449 --> Val, Gly-1464 --> Glu, and Ile-1572 --> Thr. To determine what effects these mutations have on IGF2R function, mutant and wild-type FLAG epitope-tagged IGF2R constructs lacking the transmembrane and cytoplasmic domains were characterized for binding of insulin-like growth factor (IGF)-II and a mannose 6-phosphate-bearing pseudoglycoprotein termed PMP-BSA (where PMP is pentamannose phosphate and BSA is bovine serum albumin). The Ile-1572 --> Thr mutation eliminated IGF-II binding while not affecting PMP-BSA binding. Gly-1449 --> Val and Cys-1262 --> Ser each showed 30-60% decreases in the number of sites available to bind both (125)I-IGF-II and (125)I-PMP-BSA. In addition, the Gln-1445 --> His mutant underwent a time-dependent loss of IGF-II binding, but not PMP-BSA binding, that was not observed for wild type. In all, four of the five cancer-associated mutants analyzed demonstrated altered ligand binding, providing further evidence that loss of IGF2R function is characteristic of certain cancers.
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PMID:Disruption of ligand binding to the insulin-like growth factor II/mannose 6-phosphate receptor by cancer-associated missense mutations. 1044 21

MUC1 mucin is a target protein for many monoclonal antibodies. Human MUC1 detected by a murine anti-KL-6 monoclonal antibody that recognizes a sialylated carbohydrate chain has been designated KL-6/MUC1. Given the heterogeneous antigenicity of KL-6/MUC1, we established a new murine monoclonal antibody, H9, that reacts with epitope DTRP (Asp-Thr-Arg-Pro) peptides within the immunodominant region of the tandem repeat of MUC1 mucin. The reactivity of the H9 antibody differs from that of other previously reported antibodies that recognize the tandem repeat region of MUC1. Immunohistochemical experiments indicate that the reactivity of the H9 antibody is similar to that of other antibodies directed against MUC1 core proteins. A new cancer-associated protein detected by a sandwich assay using the H9 antibody as a catcher and the KL-6 antibody as a tracer is designated HK9. Serum HK9 levels showed a high expression level in lung cancer: 51% (19/37 cases) for adenocarcinoma, 39% (11/28 cases) for squamous cell carcinoma, and 67% (10/15 cases) for small cell carcinoma. The HK9 expression in lung cancer increased with cancer progression. These findings suggest monoclonal antibody H9 to be a novel antibody that reacts with an epitope within the tandem repeat region of MUC1, and that the cancer-associated antigen HK9 may have useful tumor-associated properties.
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PMID:A novel monoclonal antibody, H9, directed against the core protein of MUC1 mucin. 1067 62

Mouse Frizzled-8, encoding a WNT receptor, is a potent cancer-associated gene to activate the beta-catenin-TCF pathway. However, these is a possibility that mouse Frizzled-8 might be a pseudogene, because structure and expression profile of mouse Frizzled-8 mRNA are still unclear. We have cloned and characterized the human Frizzled-8 (FZD8) gene, a human homologue of mouse Frizzled-8. Comparison between FZD8 genome clones and FZD8 cDNA clones isolated in this study revealed no intron within the FZD8 gene. FZD8 was found to encode a 694 amino-acid polypeptide with the frizzled-like cysteine-rich domain, seven transmembrane domains, and the C-terminal Ser/Thr-X-Val motif. Among human FZD family, FZD8 was most homologous to FZD5 (total amino-acid identity 69.1%). The 4.0-kb FZD8 mRNA was detected in fetal kidney and brain, and also in adult kidney, heart, pancreas, and skeletal muscle. These results indicate that human FZD8 is not a pseudogene. The FZD8 gene was mapped to human chromosome 10p11.2 by fluorescence in situ hybridization. Among human cancer cell lines, FZD8 was relatively highly expressed in HeLa S3 (cervical uterus cancer) and A549 (lung cancer). Up-regulation of FZD8 might play key roles in several types of human cancer through activation of the beta-catenin-TCF pathway.
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PMID:Molecular cloning and characterization of human Frizzled-8 gene on chromosome 10p11.2. 1129 46

The Sialyl-Tn antigen (Sialyl alpha-Ser/Thr) is expressed as a cancer-associated antigen on the surface of cancer cells. Its presence is associated with a poor prognosis in patients with colorectal and other cancers. We previously reported that Sialyl-Tn expression in LSC human colon cancer cells could be explained by a specific lack of the activity of core 1 beta3-Gal-transferase (Brockhausen et al., Glycoconjugate J. 15, 595-603, 1998) and an inability to synthesize the common O-glycan core structures. To support this mechanism, or find other mechanisms to explain Sialyl-Tn antigen expression, we investigated the O-glycosylation pathways in clonal rat colon cancer cell lines that were selected for positive or negative expression of Sialyl-Tn antigen, and compared these pathways to those in normal rat colonic mucosa. Normal rat colonic mucosa had very active glycosyltransferases synthesizing O-glycan core structures 1 to 4. Several sialyl-, sulfo- and fucosyltransferases were also active. An M type core 2 beta6-GlcNAc-transferase was found to be present in rat colon mucosa and all of the rat colon cancer cells. O-glycosylation pathways in rat colon cancer cells were significantly different from normal rat colonic mucosa; for example, rat colon cancer cells lost the ability to synthesize O-glycan core 3. All rat colon cancer cell lines, regardless of the Sialyl-Tn phenotype, expressed glycosyltransferases assembling complex O-glycans of core 1 and core 2 structures (unlike human LSC colon cancer cells which lack core 1 beta3-Gal-transferase activity). It was the activity of CMP-sialic acid:GalNAc-mucin alpha6-sialyltransferase that coincided with Sialyl-Tn expression. Sialyl-Tn negative cells had a several fold higher activity of core 2 beta6-GlcNAc-transferase which synthesizes complex O-glycans that may mask adjacent Sialyl-Tn epitopes. The results suggest a new mechanism controlling Sialyl-Tn expression in cancer cells.
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PMID:Pathways of mucin O-glycosylation in normal and malignant rat colonic epithelial cells reveal a mechanism for cancer-associated Sialyl-Tn antigen expression. 1130 20

In the present work we demonstrate that the cancer-associated O-glycosylated Tn antigen (GalNAc-O-Ser/Thr) is expressed by the cestode Echinococcus granulosus. This antigen was detected in both larval and adult worm extracts, with the highest specific activity observed in the adult excretion/secretion preparation. Histochemical analysis showed that Tn is preferentially expressed in the parenchyma in both parasite stages and the external part of tegument in adult worms. A similar pattern was observed for sialyl-Tn, a related O-linked antigen. Tn glycoproteins from protoscoleces were resolved by SDS-PAGE in two main components of 43 and 49 kDa. After purification, this material was reactive with lectins which bind GlcNAc/sialic acid, GalNAc, and T antigen. In a preliminary evaluation, high levels of Tn antigen were detected in serum samples from patients with hydatid cyst, suggesting that the measure of Tn in serum could be a biomarker of this disease, although extensive work is necessary in order to determine the clinical usefulness of this assay. The results reported here, the first evidence of O-glycosylation pathways in E. granulosus and the presence of Tn antigen in cestodes, suggest that the evaluation of O-glycosylated antigens might give new insights in the host-parasite relationship.
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PMID:O-glycosylation in Echinococcus granulosus: identification and characterization of the carcinoma-associated Tn antigen. 1146 93


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