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

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Query: EC:2.4.99.6 (sialyltransferase)
1,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sialyltransferase (CMP-sialic acid:asialofetuin sialyltransferase) and human mammary epithelial antigens (HME-Ags, cell surface antigens specific to human mammary epithelial cells) were determined in plasma of nude mice grafted with breast and non-breast human tumors to assess their possible usefulness as breast cancer markers. The plasma transferase activity was significantly higher (p less than 0.01) in tumor groups relative to the control. However, no significant difference (p less than 0.05) could be found in the transferase level between breast and non-breast tumor groups, showing the enzyme's lack of specificity for breast cancer. Furthermore, the surgical procedure performed on the control normal healthy group (no tumor), resulted in an important increase of the enzyme level, while HME-Ags remained unchanged. HME-Ags were essentially negative in control as well as non-breast tumor groups. After surgical removal of breast tumors, HME-Ags level dropped drastically to the background level (from 122 to less than 30 ng/ml plasma). These data indicate that HME-Ags are more sensitive and specific than sialyltransferase as markers for human breast tumor, and suggest that HME-Ags may be clinically useful in the early detection of breast cancer as well as in the followup of patients with metastatic breast tumor.
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PMID:Breast cancer markers: comparison between sialyltransferase and human mammary epithelial antigens (HME-Ags) for the detection of human breast tumors grafted in nude mice. 397 47

Membrane glycopeptides were examined in human colonic adenocarcinoma and normal colonic mucosa. The carbohydrates of membrane glycopeptides were found to be markedly reduced in tumor tissue and the relative proportions of the various sugars were altered. Although all of the sugars were lower in tumor tissue when compared to the adjacent normal mucosa, galactosamine, fucose, and sialic acid were more significantly reduced. Examination of the blood group activity and lectin-binding properties of membrane glycopeptides revealed that specific carbohydrate structures had changed in the tumor tissue. Most striking of these changes was the disappearance of glycoprotein-associated blood group A activity. Assay of the enzyme responsible for synthesis of the blood group A determinant showed that this glycosyltransferase activity was greatly diminished in tumor tissue. A galactosyltransferase and a fucosyltransferase were also significantly lower in the tumor tissue whereas the levels of another galactosyltransferase and a sialyltransferase were unaltered. Glycosidase activities in the normal and tumor tissues were similar. The results show that an alteration in glycoprotein biosynthesis occurred during tumorigenesis that resulted in a modified membrane glycoprotein composition and that these changes are probably a reflection of reduced levels of the enzymes responsible for glycoprotein synthesis.
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PMID:Alterations of membrane glycopeptides in human colonic adenocarcinoma. 414 May 12

Elevated levels of glycoprotein:sialyltransferase activity (EC 2.4.99.1; CMP-N-acetylneuraminate: D-galactosyl-glycoprotein N-acetylneuraminyltransferase) were found in human malignant neoplastic tissues compared to normal, benign, and "preneoplastic" tissues. This increase was not due to the cell density of the tissue. Elevated levels of certain proteases and glycosidases were also found. The increase in transferase activity may be associated with altered membrane synthesis in the neoplastic state; changes in the activity of degradative enzymes may be associated with tumor invasiveness and maintenance of the neoplastic state. Measurements on human tumors are possibly more directly relevant to cancer than those described for transformed fibroblastic cells in vitro.
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PMID:Enzyme activity in invasive tumors of human breast and colon. 436 73

1. The specific activities of sialytransferase in metastatic tumor sites were 5-37% of those of uninvolved non-cancerous tissue. The non-cancerous host tissues had a slightly lower average sialyltransferase activity than that of non-pathological control livers (986 vs 1194 dpm/min/mg protein). 2. The levels of total and bound sialic acid are increased 1.4 to 7.2-fold in homogenates, supernatants and resuspended pellets of metastatic tumor sites compared to non-cancerous and non-pathological control livers. For all these tissues, 24-29% of the bound sialic acid is found on soluble components (in the 16,300 g supernatant). 3. Soluble sialoglycoconjugates from most metastatic tumor sites give gel filtration profiles different from those of non-cancerous and non-pathological control livers.
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PMID:Sialyltransferase, sialic acid and sialoglycoconjugates in metastatic tumor and human liver tissue. 617 43

In rats bearing a solid form of AH-109A hepatoma, serum asialofetuin sialyltransferase activity was significantly increased. In order to identify the source of the increased serum sialyltransferase, the asialofetuin sialyltransferase activities of normal and host liver, tumor, and normal and host serum were studied by phosphocellulose column chromatography. While normal and host (day 17) livers exhibited two peaks, namely, transferases I and II, which were previously shown to be the sialylated and unsialylated species, respectively, of beta-galactoside alpha 2 leads to 6 sialyltransferase, the tumor exhibited a single peak of the enzyme, which was a sialylated species (as was transferase I) but was eluted at a position clearly distinguishable from that of either transferase I or transferase II. Under these conditions, both normal and host (day 17) sera were found to contain transferase I but not the tumor-type enzyme. The results have been interpreted as indicating that in rats with AH-109A, the tumor is not the source of the increased serum sialyltransferase. In these rats as well as in normal rats, serum sialyltransferase appears to originate mainly from the liver, whose sialyltransferase activity was also increased in rats with AH-109A.
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PMID:Increase in serum sialyltransferase in tumor-bearing rats: the origin and nature of the increased enzyme. 619 46

Proteolytic and sialyltransferase activities were determined in extracts of 65 human primary breast tumors, 6 lymph node metastases, 6 fibroadenomas and 27 normal tissues. Using proteins and synthetic selective substrates, we observed the presence of collagen-peptidases, plasminogen activator, cathepsin-B and cathepsin-D-like enzymes, and sialyltransferase. No active or trypsin-activatable type-IV collagenase activity was detected. Although individual variations between tumors were large, proteinase and sialyltransferase contents were significantly elevated in malignant breast tissues. Enzyme activities were found to be related to the epithelial volume of the tumor. No significant correlation was found between the proteinase or sialyltransferase activities and the degree of differentiation of the tumor cells, or the degree to which tumors had metastasized to regional lymph nodes. Since large variations of enzyme levels apparently reflect the heterogeneity of epithelial cell densities in tumor samples, proteolytic or sialyltransferase activities cannot therefore be used as a measure of quantitative evaluation of invasive properties in breast cancer.
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PMID:Proteinases and sialyltransferase in human breast tumors. 632 71

The activities of serum sialyltransferase were determined in patients with brain tumors. Blood samples from normal volunteers were used as controls. Serum specimens were obtained from patients with brain tumors both before and after operations. The preoperative serum sialyltransferase activities of the brain metastasis group showed significant increase, but the enzyme levels decreased after removal of the tumor. The serum sialyltransferase activities in the glioma group and the neurilemoma group increased significantly after operation, but no significant difference was found between the preoperative means of these two groups and that of the control. Surgical treatment produced significant differences between the preoperative and the postoperative serum sialyltransferase activities in the brain metastasis and the glioma and neurilemoma groups. Alterations of this enzyme in the blood of patients with brain tumors and its possible clinical applications are discussed.
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PMID:Alterations in serum sialyltransferase activities in patients with brain tumors. 649 62

The effect of phorbol esters on ganglioside metabolism in contact-inhibited Chinese hamster V79 cells was examined. Three phorbol esters of varying structure and tumor-promoting activity were used. Treatment of cells with tumor-promoting phorbol esters resulted in accumulation of gangliosides and increased incorporation of [1-14C]palmitate and [9-3H]sialic acid into gangliosides. Moreover, the phorbol esters were found to increase the activity of CMP-sialic acid: lactosylceramide sialyltransferase, the enzyme catalysing the first step in ganglioside biosynthesis. The magnitude of phorbol ester effects on V79 cell ganglioside metabolism correlated with the in vivo phorbol ester tumor-promoting activity.
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PMID:Phorbol ester-associated changes in ganglioside metabolism. 657 51

Serum sialyltransferase (SST) activity was measured 10 days after mastectomy in 153 patients with operable breast cancer. Enzyme activity declined with time in storage (1-42 months). After correction for loss of activity in storage, patients with SST activity below the median value had a longer disease-free interval (DFI) than those with SST activity above the median, and this difference remained when patients were stratified by axillary nodal status, tumor size, and tumor grade. Survival was longer in patients with low SST activity. Post-operative elevation of SST indicates a poor prognosis in patients with operable breast cancer.
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PMID:Post-operative serum sialyltransferase levels and prognosis in breast cancer. 661 79

Retinoic acid (RA) treatment of murine S91-C2 melanoma cells has been found to augment the activity of glycoprotein: sialyltransferase in a dose-dependent and time-dependent process. The enzymatic activity in cells treated with 10 microM RA reached a maximal level, 3-fold higher than in untreated cells, 72 h after initiation of treatment. In contrast, the addition of RA directly into the reaction mixture had no stimulatory effect on sialyltransferase. The endogenous glycoproteins to which sialic acid is transferred from cytidine monophosphate (CMP)-[14C] sialic acid by the action of sialyltransferase have been identified by fluorography after polyacrylamide gel electrophoresis. One of these acceptors, a glycoprotein of Mr 160 000, comigrated in gel electrophoresis with a cell surface sialoglycoprotein that can be labeled by the periodate-tritiated borohydrate procedure more intensely on intact RA-treated than on untreated cells. Removal of sialic acid residues exposed on the surface of either control or RA-treated cells enhanced 2- to 3-fold the transfer of sialic acid to endogenous acceptors. These results suggest that the increased sialyltransferase activity in RA-treated melanoma cells may be responsible for the enhanced sialylation of certain cell surface glycoproteins. RA treatment of several other tumor cell lines also resulted in stimulation of sialyltransferase activity indicating that this effect of RA is not limited to the S91-C2 melanoma cells.
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PMID:Stimulation of sialyltransferase activity of melanoma cells by retinoic acid. 664 95


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