Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The specificity of the MY.1E12 mAb that was generated by immunizing mice with human milk fat globule (HMFG) was investigated. Fluorescein isothiocyanate (FITC)-conjugated peptides corresponding to a portion of the MUC1 tandem repeat were enzymatically glycosylated with N-acetylgalactosamine, galactose, and then sialic acid. The MY.1E12 mAb was examined for its affinity to the resulting glycopeptides by fluorescence polarization. Its affinity for the peptide whose Thr within the VTS sequence bears a Neu5Ac alpha 2-3Gal beta 1-3GalNAc trisaccharide (K(d)=1.4 x 10(-7) M) was significantly higher than for the same peptide whose Thr bears an unsialylated disaccharide (K(d)=3.9 x 10(-6) M). The MY.1E12 mAb also bound strongly to a purified recombinant MUC1 fusion protein with six tandem repeats that was expressed by transfected MCF-7 breast cancer cells. The removal of sialic acids from the fusion protein significantly decreased MY.1E12 mAb reactivity, much more so than the MUC1-specific 115D8 antibody, whose epitope is known to be destroyed by desialylation. Thus, the attachment of the sialyl alpha 2-3Gal beta 1-3 beta 1-3GalNAc trisaccharide onto the Thr within the VTS motif significantly increases the binding of the MY.1E12 antibody to the MUC1 repeat sequence.
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PMID:The epitope recognized by the unique anti-MUC1 monoclonal antibody MY.1E12 involves sialyl alpha 2-3galactosyl beta 1-3N-acetylgalactosaminide linked to a distinct threonine residue in the MUC1 tandem repeat. 1237 25

The expression of the aberrant N-acetylgalactosamine (GalNAc) glycoconjugates, detected by binding of the lectin from Helix pomatia (HPA) is reported to be associated with metastatic competence and poor prognosis in a range of human adenocarcinomas, but the functional significance of the glycoconjugates in metastatic mechanisms is unknown. We have employed seven cell lines derived from normal breast epithelium, primary breast cancer and breast cancer metastases which stably express varying levels of HPA-binding glycoconjugates consistent with their derivation and phenotype. These cell lines have been thoroughly characterised and express identical profiles of HPA-binding glycoconjugates as tumour cells derived from clinical samples. Their ability to adhere to, and invade through, basement membrane components was investigated in a matrigel assay system, and the functional role of the aberrant GalNAc glycans assessed by competitive inhibition experiments using HPA. The behaviour of the cell lines in these assay systems was entirely consistent with their derivation and phenotype, but there was no evidence that the glycoconjugates of interest were functionally involved in adhesion or invasion mechanisms. Research in our laboratory is ongoing to seek a functional role for the HPA-binding glycoconjugates in other aspects of the metastatic cascade.
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PMID:Investigations into the potential role of aberrant N-acetylgalactosamine glycans in tumour cell interactions with basement membrane components. 1240 85

Our previous studies showed that expression of the GalNAcbeta1-->4GlcNAc group on N-linked oligosaccharides is associated with functional differentiation of the bovine mammary gland. In the present study, the occurrence of the GalNAcbeta1-->4GlcNAc group was established in human milk proteins and membrane glycoproteins from a human breast cancer cell line, MRK-nu-1, by structural analysis of oligosaccharides released by hydrazinolysis. Whether the expression level of the disaccharide group is affected upon malignant transformation was examined in human breast cancer specimens using Wistaria floribunda agglutinin (WFA) which interacts with oligosaccharides with N-acetylgalactosamine at their termini. Lectin blot analysis of membrane glycoprotein samples from human breast cancer specimens showed that the number of protein bands reacting with WFA, as well as their intensities, are lower in samples from primary carcinoma lesions compared with samples from surrounding normal tissues. No lectin binding was observed when the blots were treated with jack bean beta-N-acetylhexosaminidase or N-glycanase, indicating that WFA-reactive oligosaccharides are N-linked. A histochemical study of tissue specimens from 92 patients with breast cancer revealed that the reduced WFA staining levels in primary carcinoma lesions correlate with advancing clinical stages and prognostic status (i.e., 58% of patients in a group showing reduced/negative staining died of disease recurrence, whereas more than 90% of those in the positive staining group survived for 5 years after surgery). These results indicate that reduced expression of beta-N-acetylgalactosaminylated N-linked oligosaccharides on primary carcinoma lesions predicts a poor prognosis for patients with breast cancer.
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PMID:Prognostic significance of reduced expression of beta-N-acetylgalactosaminylated N-linked oligosaccharides in human breast cancer. 1271 46

Sialyl-Tn antigen (STn) is a cancer associated carbohydrate antigen over-expressed in several cancers including breast cancer, and currently associated with more aggressive diseases and poor prognosis. However, the commonly used breast cancer cell lines (MDA-MB-231, T47-D and MCF7) do not express STn antigen. The key step in the biosynthesis of STn is the transfer of a sialic acid residue in alpha2,6-linkage to GalNAc alpha-O-Ser/Thr. This reaction is mainly catalyzed by a CMP-Neu5Ac GalNAc alpha2,6-sialyltransferase: ST6GalNAc I. In order to generate STn-positive breast cancer cells, we have cloned a cDNA encoding the full-length human ST6GalNAc I from HT-29-MTX cells. The stable transfection of MDA-MB-231 with an expression vector encoding ST6GalNAc I induces the expression of STn antigen at the cell surface. The expression of STn short cuts the initial O-glycosylation pattern of these cell lines, by competing with the Core-1 beta1,3-galactosyltransferase, the first enzyme involved in the elongation of O-glycan chains. Moreover, we show that STn expression is associated with morphological changes, decreased growth and increased migration of MDA-MB-231 cells.
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PMID:Expression of sialyl-Tn antigen in breast cancer cells transfected with the human CMP-Neu5Ac: GalNAc alpha2,6-sialyltransferase (ST6GalNac I) cDNA. 1282 Jul 22

Sialyl-Tn is a carbohydrate antigen overexpressed in several epithelial cancers including breast cancer, and usually associated with poor prognosis. Sialyl-Tn is synthesized by a CMP-Neu5Ac: GalNAc alpha2,6-sialyltransferase: ST6GalNAc I, which catalyzes the transfer of a sialic acid residue in alpha2,6-linkage to the GalNAcalpha1-O-Ser/Thr structure. The resulting disaccharide (Neu5Acalpha2-6GalNAcalpha1-O-Ser/Thr) cannot be further elongated and sialyl-Tn expression results therefore in a shortening of the O-glycan chains. However, usual breast cancer cell lines express neither ST6GalNAc I nor sialyl-Tn antigen. We have previously shown that stable transfection of MDA-MB-231 cells with the hST6GalNAc I cDNA induces the sialyl-Tn antigen expression at the cell surface and leads to a decreased cell growth and an increased cell migration. We describe herein the generation of new T47-D clones expressing sialyl-Tn antigen after hST6GalNAc I cDNA stable transfection. sialyl-Tn antigen is carried by several high molecular weight membrane bound O-glycoproteins, including MUC1. We show that sialyl-Tn expression induces a decrease of cell growth and adhesion, and an increase of cell migration in sialyl-Tn positive clones compared to mock transfected cells. These observations show that the alteration of the O-glycans pattern is sufficient to modify the biological features of cancer cells. These T47-D sialyl-Tn expressing clones might allow further in vivo investigation to determine precisely the impact of such O-glycosylation modifications on breast cancer development.
Breast Cancer Res Treat 2005 Mar
PMID:Stable expression of sialyl-Tn antigen in T47-D cells induces a decrease of cell adhesion and an increase of cell migration. 1577 May 30

Based on BLAST analysis of the human and mouse genome databases using the human CMP sialic acid; alpha2,8-sialyltransferase cDNA (hST8Sia I; EC 2.4.99.8), a putative sialyltransferase gene, was identified on human chromosome 10. The genomic organization was found to be similar to that of hST8Sia I and hST8Sia V. Transcriptional expression analysis showed that the newly identified gene was constitutively expressed at low levels in various human tissues and cell lines. We have isolated a full-length cDNA clone from the breast cancer cell line MCF-7 that encoded a type II membrane protein of 398 amino acid residues with the conserved motifs of sialyltransferases. We have established a mammary cell line (MDA-MB-231) stably transfected with the full-length hST8Sia VI and the analysis of sialylated carbohydrate structures expressed at the cell surface clearly indicated the disappearance of Neu5Acalpha2-3-sialylated structures. The transient expression of a truncated soluble form of the enzyme in either COS-7 cells or insect Sf-9 cells led to the production of an active enzyme in which substrate specificity was determined. Detailed substrate specificity analysis of the hST8Sia VI recombinant enzyme in vitro, revealed that this enzyme required the trisaccharide Neu5Acalpha2-3Galbeta1-3GalNAc (where Neu5Ac is N-acetylneuraminic acid and GalNAc is N-acetylgalactosamine) to generate diSia (disialic acid) motifs specifically on O-glycans.
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PMID:Molecular cloning and expression of a human hST8Sia VI (alpha2,8-sialyltransferase) responsible for the synthesis of the diSia motif on O-glycosylproteins. 1612 58

An incomplete elongation of O-glycan saccharide chains in mucins have been found in epithelial cancers, leading to the expression of shorter carbohydrate structures, such as the Tn antigen (GalNAc-O-Ser/Thr). This antigen is one of the most specific human cancer-associated structures and is capable of inducing effective immune responses against cancer cells. We aimed to investigate the causes of the expression of Tn antigen in the Tn-rich MCF-7 breast cancer cell line focusing on the first step of the O-glycosylation process. Interestingly, amino acid sequences derived from "non-mammary" apomucins (MUC5B and MUC6) were very good acceptor substrates for ppGalNAc-Ts, which are the enzymes catalyzing the Tn antigen synthesis. MUC6 peptide glycosylation with MCF-7 microsome extracts as source of ppGalNAc-T activity yielded 95% conversion of the peptide into MUC6-Tn. In addition, the MUC6-Tn glycopeptide was a poor acceptor substrate for core 1 beta3Gal-T, the next enzyme involved in the saccharide chain biosynthesis, yielding only 5% conversion of MUC6-Tn into MUC6-TF. These results indicate that non-mammary apomucin expression could be responsible, at least in part, for Tn antigen expression in MCF-7 breast cancer cells due to a combined action on glycosyltransferases: an increase of ppGalNAc-T activity and a decrease of core 1 beta3Gal-T activity. Our hypothesis is supported by experiments in vivo showing that (a) native MUC6 glycoproteins express the Tn antigen in MCF-7 cells and (b) Tn antigen expression is increased after transfection with a construct encoding for a MUC6 recombinant protein into the low Tn-expressing breast cancer cell T47D. These results open new horizons in breast cancer glycoimmunology, stressing the potential role of non-mammary apomucins.
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PMID:Molecular basis of incomplete O-glycan synthesis in MCF-7 breast cancer cells: putative role of MUC6 in Tn antigen expression. 1614 Sep 58

In cancer, mucins are aberrantly O-glycosylated, and consequently, they express tumor-associated antigens such as the Tn determinant (alpha-GalNAc-O-Ser/Thr). As compared with normal tissues, they also exhibit a different pattern of expression. In particular, MUC6, which is normally expressed only in gastric tissues, has been detected in intestinal, pulmonary, colorectal, and breast carcinomas. Recently, we have shown that the MCF7 breast cancer cell line expresses MUC6-Tn glycoproteins in vivo. Cancer-associated mucins show antigenic differences from normal mucins, and as such, they may be used as potential targets for immunotherapy. To develop anticancer vaccines based on the Tn antigen, we prepared several MUC6-Tn glycoconjugates. To this end, we performed the GalNAc enzymatic transfer to two recombinant MUC6 proteins expressed in Escherichia coli, using UDP-N-acetylgalactosamine: polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts), which catalyze in vivo the Tn antigen synthesis. We used either a mixture of ppGalNAc-Ts from MCF7 breast cancer cell extracts or a recombinant ppGalNAc-T1. In both cases, we achieved the synthesis of MUC6-Tn glycoconjugates at a semi-preparative scale (mg amounts). These glycoproteins displayed a high level of Tn antigens, although the overall density depends on both enzyme source and protein acceptor. These MUC6-Tn glycoconjugates were recognized by two anti-Tn monoclonal antibodies that are specific to human cancer cells. Moreover, the MUC6-Tn glycoconjugate glycosylated using MCF7 extracts as the ppGalNAc-T source was able to induce immunoglobulin G (IgG) antibodies that recognized a human tumor cell line. In conclusion, the large-scaled production of MUC6 with tumor-relevant glycoforms holds considerable promise for developing effective anticancer vaccines, and further studies of their immunological properties are warranted.
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PMID:Enzymatic large-scale synthesis of MUC6-Tn glycoconjugates for antitumor vaccination. 1644 49

Carbohydrate chains of cancer glycoprotein antigens contain major outer changes dictated by tissue-specific regulation of glycosyltransferase genes, the availability of sugar nucleotides, and competition between enzymes for acceptor intermediates during glycan elongation. However, it is evident from recent studies with recombinant mucin probes that the final glycosylation profiles of mucin glycoproteins are mainly determined by the cellular repertoire of glycosyltransferases. Hence, we examined various cancer cell lines for the levels of fucosyl-, beta-galactosyl, beta-N-acetylgalactosaminyl-, sialyl-, and sulfotransferase activities that generate the outer ends of the oligosaccharide chains. We have identified glycosyltransferases activities at the levels that would give rise to O-glycan chains as reported by others in breast cancer cell lines, T47D, ZR75-1, MCF-7, and MDA-MB-231. Most breast cancer cells express Gal-3-O-sulfotransferase specific for T-hapten Gal beta1-->3GalNAc alpha-, whereas the enzyme from colon cancer cells exhibits a vast preference for the Gal beta1,4GlcNAc terminal unit in O-glycans. We also studied ovarian cancer cells SW626 and PA-1 and hepatic cancer cells HepG2. Our studies show that alpha1,2-L-fucosyl-T, alpha(2,3) sialyl-T, and 3-O-Sulfo-T capable of acting on the mucin core 2 tetrasaccharide, Gal beta1,4GlcNAc beta1,6(Gal beta1,3)GalNAc alpha-, can also act on the Globo H antigen backbone, Gal beta1,3GalNAc beta1,3Gal alpha-, suggesting the existence of unique carbohydrate moieties in certain cancer-associated glycolipids. Briefly, our study indicates the following: (i) 3'-Sulfo-T-hapten has an apparent relationship to the tumorigenic potential of breast cancer cells; (ii) the 3'-sulfo Lewis(x), the 3-O-sulfo-Globo unit, and the 3-fucosylchitobiose core could be uniquely associated with colon cancer cells; (iii) synthesis of a polylactosamine chain and T-hapten are favorable in ovarian cancer cells due to negligible sialyltransferase activities; and (iv) a 6'-sialyl LacNAc unit and 3'-sialyl T-hapten appear to be prevalent structures in hepatic cancer cell glycans. Thus, it is apparent that different cancer cells are expressing unique glycan epitopes, which could be novel targets for cancer diagnosis and treatment.
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PMID:The pattern of glycosyl- and sulfotransferase activities in cancer cell lines: a predictor of individual cancer-associated distinct carbohydrate structures for the structural identification of signature glycans. 1654 47

Aberrant carbohydrate expression frequently occurs in breast cancer and may endow cells with metastatic potential. Here we first studied the relationship between expression of Vicia villosa agglutinin (lectin) (VVA)-binding carbohydrates and aggressive breast cancer. We then investigated the molecular characteristics of these glycoproteins and compared them with those of glycoproteins recognized by the mouse anti-Tn monoclonal antibody (MAb) HB-Tn1. Histochemical studies of samples from 322 cases of invasive ductal carcinoma demonstrated that VVA-binding carbohydrate expression correlated with tumor stage, lymphatic invasion, and lymph node metastasis (p=0.0385, p=0.0019, and p=0.0430. respectively). Western blotting analysis of frozen materials from 39 cases, under denaturing and reducing conditions, revealed that the major cancer cell-specific VVA-binding proteins were molecules of about 30, 33, and >200 kDa. Cases expressing the approximately 33 kDa molecule had significant lymphatic invasion more frequently than did cases not expressing this molecule (p=0.0076). Binding of VVA to the approximately 30 and approximately 33 kDa molecules was completely lost by preincubation of VVA with 1 mM Tn antigen (N-acetylgalactosamine alpha1-O-serine). The VVA-binding molecules appeared to react with VU-3C6 anti-MUC1 MAb. Expression of HB-Tn1 in breast cancer cells showed significant correlation with expression of VVA-binding carbohydrate(s) (p<0.0001) but HB-Tn1 reactivity was not clearly related to breast cancer aggressiveness. Because anti-Tn MAbs bound to Tn antigen clusters, we concluded that atypical MUC1 bearing the noncluster form of Tn antigen is implicated in aggressive growth of primary breast cancer cells, particularly in lymphatic metastasis.
Breast Cancer Res Treat 2006 Jul
PMID:Expression of Vicia villosa agglutinin (VVA)-binding glycoprotein in primary breast cancer cells in relation to lymphatic metastasis: is atypical MUC1 bearing Tn antigen a receptor of VVA? 1675 27


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