Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human chorionic gonadotropin (hCG), human luteinizing hormone, human thyroid-stimulating hormone, and human follicle-stimulating hormone are closely related family of proteins which share a common alpha-subunit. However, their sugar moieties are quite different. hCG contains five acidic asparagine-linked sugar chains. These five sugar chains are derived by sialylation from three neutral oligosaccharides: two biantennary (N-1 and N-2) and one monoantennary (N-3) complex-type oligosaccharides. Although hCG purified from the urine of pregnant women is more enriched in sialylated sugar chains than that purified from placenta, the molar ratio of N-1, N-2, and N-3 of these two hCGs are the same (1:2:1). Comparative study of the sugar moieties of the alpha- and beta-subunits of hCG revealed that alpha contains 1 mol each of N-2 and N-3, while beta contains 1 mol each of N-1 and N-2. This specific distribution of oligosaccharides at the four asparagine loci of the hCG molecule is now helping us to consider the functional role of the sugar moiety of glycohormones. hCG is produced not only by the trophoblast but also by various trophoblastic diseases. The hCGs purified from the urine of patients with hydatidiform mole contain the same oligosaccharides as normal hCG. However, those from the urine of choriocarcinoma patients contain five additional neutral oligosaccharides. In contrast, hCGs from invasive-mole patients contain three of the five oligosaccharides, specifically found in choriocarcinoma hCGs. The malignant transformational change of the sugar moiety of hCG can be explained by an increase of a fucosyltransferase, which forms the Fuc alpha 1----6GlcNAc group and by ectopic expression and subsequent modification of N-acetylglucosaminyltransferase IV. The appearance of tumor-specific sugar chains of hCG has been used to develop a new diagnostic method for invasive mole and choriocarcinoma.
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PMID:Structures, function, and transformational changes of the sugar chains of glycohormones. 283 26

Altered glycosylation is widely observed in glycoproteins produced by tumors. One of the most consistently observed alterations is the increase of larger asparagine-linked sugar chains in the plasma membrane glycoproteins. This phenomenon is brought about by the increase of N-acetylglucosaminyltransferase V, which is responsible for the formation of the GlcNAc beta 1----6Man alpha-1----6 group. The enrichment of the complex-type sugar chains containing the -GlcNAc beta 1----6(-GlcNAc beta 1----2)Man alpha 1----6 group is correlated with tumorigenicity and metastasic potential of tumor cells. Comparative study of the sugar chains of human chorionic gonadotropin isolated from the urine of pregnant women and of patients with trophoblastic diseases including choriocarcinoma revealed that many new oligosaccharides are included in the tumor hCG. The altered glycosylation of hCG is brought about by the ectopic expression of N-acetylglucosaminyltransferase IV. With use of this altered glycosylation, a novel method useful for the diagnosis of choriocarcinoma was established.
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PMID:Structural changes induced in the sugar chains of glycoproteins by malignant transformation of producing cells and their clinical application. 285 76

Paper electrophoresis of the oligosaccharide fraction obtained by hydrazinolysis of human chorionic gonadotropin (HCG), which was purified from the urine of two patients with invasive mole, gave fractionation patterns different from those of normal and hydatidiform mole HCGs. Structural study of the oligosaccharides in each fraction revealed that the triantennary complex-type asparagine-linked sugar chains, specifically found in choriocarcinoma HCGs, were included in the two HCG samples. However, the unusual biantennary complex type sugar chains, which are also specific for the tumor HCGs, were not detected at all. This result indicated that abnormal expression of N-acetylglucosaminyl-transferase IV during the development of choriocarcinoma occurs in two steps: (a) ectopic expression of the regular N-acetylglucosaminyltransferase IV; and (b) modification of the substrate specificity of the enzyme.
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PMID:Structural differences found in the asparagine-linked sugar chains of human chorionic gonadotropins purified from the urine of patients with invasive mole and with choriocarcinoma. 295 51

Comparative study of the asparagine-linked sugar chains of hCGs purified from urine of pregnant women and of choriocarcinoma patients revealed that extensive and structural changes occur common in the sugar chains of tumor hCGs. The changes can be ascribed to enhancement of an alpha-fucosyltransferase that forms the Fuc alpha 1----6GlcNAc group in the sugar chains and the appearance of N-acetylglucosaminyltransferase IV.
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PMID:[Abnormal sugar chains found in tumor glycoproteins]. 396 42

Human chorionic gonadotropin (hCG) contains five acidic N-linked sugar chains, which are derived from three neutral oligosaccharides by sialylation. Each of the two subunits (hCGalpha and hCGbeta) of hCG contain two glycosylated Asn residues. Glycopeptides, each containing a single glycosylated Asn, were obtained by digestion of hCGalpha with trypsin, and of hCGbeta with chymotrypsin and lysyl endopeptidase. Comparative study of the sugar chains of the four glycopeptides revealed the occurrence of site-directed glycosylation. Studies of the sugar chains of hCGs, purified from urine of patients with various trophoblastic diseases, revealed that choriocarcinoma hCGs contain sialylated or non-sialylated forms of eight neutral oligosaccharides. In contrast, hCGs from invasive mole patients contain sialyl derivatives of five neutral oligosaccharides. The structural characteristics of the five neutral oligosaccharides, detected in choriocarcinoma hCGs but not in normal placental hCGs, indicate that N-acetylglucosaminyltransferase IV (GnT-IV) is abnormally expressed in the malignant cells. This supposition was confirmed by molecular biological study of GnT-IV in placenta and choriocarcinoma cell lines. The appearance of tumor-specific sugar chains in hCG has been used to develop a diagnostic method of searching for malignant trophoblastic diseases. In addition, a summary of the current knowledge concerning the functional role of N-linked sugar chains in the expression of the hormonal activity of hCG has been presented.
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PMID:Structure, pathology and function of the N-linked sugar chains of human chorionic gonadotropin. 1057 Oct 21