Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intestinal metaplasia is often associated with human gastric carcinoma. Intestinalization seems to be a typical example of abnormal differentiation and is possibly a precancerous state. For investigation of intestinal metaplasia, a method for visualizing disaccharidases using Tes-Tape was developed; this method was applied to many specimens of stomach surgically removed for the treatment of gastric carcinoma. More than 130 specimens of human stomach were investigated. Intestinalization was classified into types I and II intestinal metaplasia. In type I intestinal metaplasia, sucrase, maltase, trehalase, alkaline phosphatase, goblet cells, and Paneth cells were present; while the type II intestinal metaplasia, sucrase and maltase were present but alkaline phosphatase and trehalase were absent. In type II, goblet cells were present but not Paneth cells. The histochemical technique for sucrase was newly devised. Some of the villi with goblet cells in the area of intestinalization in the stomach were not stained by sucrase activity, although most of the villi were stained. The presence of a third type of metaplasia was suggested. Purified sucrases obtained from the intestine and one case of type I intestinal metaplasia showed blood group reactivity due to the oligosaccharide side chain. However, purified sucrases obtained from two cases of type II intestinal metaplasia were negative in blood group reactivity. A close relation between distribution of alpha-fetoprotein and carcinoembryonic antigen in gastric carcinoma and that in surrounding intestinal metaplasia is discussed.
Cancer Res 1976 Jul
PMID:Precancerous changes in the stomach. 5 22

The brush border of normal small-intestine epithelial cells is rich in enzymes that are involved in the digestive process. Such molecules can be used as markers to analyze cell lineages and differentiation properties of colorectal cancers. Monoclonal antibodies detecting dipeptidyl peptidase-IV, aminopeptidase N, endopeptidase F, sucrase-isomaltase, alkaline phosphatase, maltase-glucoamylase and lactase have been used to analyze the phenotype of colorectal cancers, adjacent mucosa and histologically normal distant mucosa. The avidin-biotin peroxidase complex method was used. Expression of dipeptidyl peptidase-IV, aminopeptidase N, sucrase-isomaltase and alkaline phosphatase was common in non-neoplastic mucosa adjacent to, and distant from, the tumor; in contrast, endopeptidase F, maltase-glucoamylase and lactase were rarely expressed in normal distant mucosa and more frequently expressed in mucosa adjacent to the tumor. Dipeptidyl peptidase-IV, aminopeptidase N, endopeptidase F, sucrase-isomaltase and alkaline phosphatase were frequently expressed in colorectal cancers, whereas maltase-glucoamylase and lactase were rarely expressed. Two general patterns of antibody reactivity were observed: diffuse cytoplasmic and apical; apical reactivity was generally associated with more differentiated tumors. A logistic predictive regression model indicated that enzyme expression in colorectal cancers followed a coordinate pattern, but was unrelated to the location of the tumor, Dukes stage or differentiation grade. In conclusion, expression of brush-border-associated enzymes occurs frequently in colorectal cancers and is regulated in a co-ordinated manner. These markers can be used for the phenotypic sub-classification of colorectal cancers.
Int J Cancer 1992 May 08
PMID:Intestinal brush-border-associated enzymes: co-ordinated expression in colorectal cancer. 134 6

Expression of brush border hydrolases can reflect the state of differentiation of an epithelium. To determine if expression of these enzymes is disordered in patients with neoplastic or hyperplastic lesions, the activities of alkaline phosphatase, maltase, and dipeptidyl peptidase IV were measured spectrophotometrically in colonoscopic biopsies from the proximal and distal colon and rectum in 50 controls, 17 patients with large bowel adenomas, 29 with carcinoma, and 9 with hyperplastic polyps. In normal controls, a descending cecorectal gradient of alkaline phosphatase activities and an ascending gradient of maltase activities were seen (P < 0.001). Though regional patterns of expression were generally preserved in disease groups, there were significant differences of activities across patient groups for alkaline phosphatase (greater in cancer, adenoma, and hyperplastic groups than in normals; P < 0.05) and for dipeptidyl peptidase IV (greater in hyperplastic polyp group than normals, greater in adenoma than cancer group; P < 0.05). Compared with normal controls, abnormalities of site-specific activities were confined to the rectum in patients with adenoma (maltase decreased, P = 0.02; dipeptidyl peptidase IV increased, P < 0.01) or with carcinoma (alkaline phosphatase increased, P = 0.03) but dipeptidyl peptidase IV activities were increased in all regions in bowels bearing hyperplastic polyps (P < 0.01). These data suggest that neoplastic and hyperplastic lesions, while focal in nature, occur in large bowel epithelium, which is diffusely abnormal in terms of its expression of these enzymes.
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PMID:Neoplasia and hyperplasia of large bowel: focal lesions in an abnormal epithelium. 135 42

Expression and cellular localization of brush-border enzymes (aminopeptidase N, dipeptidylpeptidase IV, lactase, maltase) in normal human colon, colonic polyps and malignant intestinal tumors were investigated with a panel of monoclonal antibodies reacting with either native or denatured proteins. The enzymes were detected on cryostat sections by indirect immunofluorescence staining, or affinity-purified and analyzed by gel electrophoresis and immunoblotting. Dipeptidylpeptidase IV, lactase and maltase were absent from all samples examined, while aminopeptidase N (APN) was detected at the basal membrane of the epithelial cells in most specimens of colon obtained from individuals free of intestinal tumors. In contrast, APN was frequently localized at the luminal membrane of the surface epithelium in large-intestinal mucosa distal to tumors, adenomas and hyperplastic polyps, and from members of hereditary colon cancer syndrome families. APN was also expressed in colonic tumors, where it was present in an apical cell membrane location in 3/23 adenomas and 14/35 adenocarcinomas examined. No correlation was found between tumor-cell invasiveness (classified by "Dukes" stage) and expression or cellular location of aminopeptidase N. Histologically, all positive tumors were moderately or well differentiated. These results suggest that aminopeptidase N is normally expressed in adult human colon, but epithelial cells in the large and small intestine differ in their ways of sorting this enzyme intracellularly and eventually inserting it into different aspects of their surface membrane, a process which may be altered at an early stage of carcinogenesis.
Int J Cancer 1992 May 28
PMID:Expression and different polarity of aminopeptidase N in normal human colonic mucosa and colonic tumors. 137 88

Previous studies have suggested that abnormal expression of enzymes characteristic of the intestinal brush border might accompany colonic neoplasia and possibly facilitate identification of epithelium at risk of malignancy. To test this possibility, the distribution of the brush border enzymes sucrase-isomaltase (SIM), maltase-glucoamylase (MGA), aminopeptidase-N (APN) and diamino-peptidylpeptidase-IV (DPPIV) were studied by the immunoperoxidase method in biopsies from the rectum and caecum of normal subjects, and neoplastic and non-neoplastic tissues from patients with adenoma or cancer. Brush border enzymes were detected by immunohistochemistry more frequently in the caecum than the rectum (P less than 0.05) of normal subjects. Diamino-peptidylpeptidase-IV and APN were present in highest concentration at the brush border of the most mature colonocytes on the luminal surface with less staining in the crypt, whereas SIM and MGA staining of the brush border was as prominent on crypt cells as surface cells. While all cancers expressed at least one enzyme, there was heterogeneity of staining within tumours and a tendency to lose polarity of enzyme expression in cells, sometimes with dense staining of the cytoplasm. Distally situated adenomas uncommonly expressed a brush border enzyme (25%) and the only enzyme expressed in them was SIM. These finding indicate that these brush border enzymes are not exclusively expressed in the small intestine; DPPIV and APN are markers of the normal mature colonocyte and should prove useful as markers of differentiation. However, the change associated with neoplasia would not appear to be of clinically predictive value.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Brush border hydrolases in normal and neoplastic colonic epithelium. 151 57

Glycoprotein processing inhibitors prevent the normal processing of N-linked glycoproteins by inhibiting specific glycosidases involved in these reactions. Thus, a number of compounds are now known that inhibit alpha-glucosidase I and alpha-glucosidase II and therefore prevent the removal of glucoses from the high-mannose chains. Some of these compounds are more potent inhibitors of one or the other of these glucosidases. There are also a number of inhibitors that affect one of the processing alpha-mannosidases (i.e. mannosidase I or mannosidase II). These compounds; especially the glucosidase inhibitors, have been valuable tools to help us understand the role of carbohydrate in viral envelope glycoprotein function. Such processing inhibitors have also been used with various tumorigenic cell lines to determine the function of N-linked glycoproteins in cancer.
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PMID:Glycosidase inhibitors as antiviral and/or antitumor agents. 181 22

Epidemiological and experimental studies indicate a strong association between an elevated colon cancer risk and increased fecal excretion of secondary bile acids, neutral sterols, and prolonged gastrointestinal transit time. Starch malabsorption, on the other hand, has been reported to be a possible protective factor in colon carcinogenesis. To study the impact of starch malabsorption on these parameters, 12 healthy volunteers consumed a diet rich in starch for two 4-week periods. During a double-blind crossover trial they received the alpha-glucosidase inhibitor acarbose (BAY g 5421) in one of the study periods and placebo in the other. During acarbose treatment stool wet weight increased by 68%, stool dry weight by 57%, and gastrointestinal mean transit time by 30%. Fecal concentrations (mg/g dry weight) of the neutral sterols coprostanol, coprostanone, campesterol, 4-cholesten-3-one, and beta-sitosterol decreased by 36.8, 48.7, 42.1, 34.6, and 39.4%, respectively, under acarbose. Concentrations of the major secondary bile acids, deoxycholic and lithocholic acid, decreased by 59.9 and 52.2%, respectively. In spite of an increased stool weight, also daily excretion (mg/day) of these two bile acids was lower under acarbose (47.9 and 36.6%, respectively) compared to placebo, whereas excretion of the main primary bile acid, cholic acid, rose from 22.58 mg/day to 379.80 mg/day during the acarbose period. The changes in fecal bile acid and neutral sterol excretion found during acarbose treatment may explain a protective effect of starch malabsorption on colon cancer development.
Cancer Res 1991 Aug 15
PMID:Effect of starch malabsorption on fecal bile acids and neutral sterols in humans: possible implications for colonic carcinogenesis. 186 44

We describe a new and unique gastric carcinoma cell line (LIM1839) derived from a young Caucasian male with rapidly progressing disease. The cell line grows with a pleomorphic morphology and has been in continuous culture for more than 3 years. The cells cannot be cloned in semi-solid agar or grown in nude mice despite numerous attempts. The karyotype of the cultured cells is highly abnormal with a large number of structural and numerical changes. Some chromosomes are dicentric and this feature has persisted in this culture. The cells express one of the small-intestinal dipeptidases, aminopeptidase N, but do not express dipeptidyl peptidase IV or the disaccharidases, sucrase isomaltase or maltase glucoamylase. The cells express high levels of EGF receptors and of messenger RNA for insulin-like growth factor II.
Int J Cancer 1989 Dec 15
PMID:A new gastric carcinoma cell line (LIM1839) derived from a young Caucasian male. 260 77

We report the relative frequency of sucrase-isomaltase (SI) antigen expression in human colonic adenocarcinoma (22/57), in peritumoral mucosa taken next to the tumor (31/41) or distant from it (29/42) as well as in 21/23 polyps. Our results are based on indirect immunofluorescence with a monoclonal antibody (MAb) specific for human intestinal SI. A regular and intense expression of SI occurred only in 6 tumor specimens. In the remaining 16 SI-positive tumor samples, labelling was heterogeneous, i.e., scattered over more or less extensive areas. A similar irregular staining pattern was also found in polyps and in peritumoral mucosa, irrespective of its distance from the tumor. Electron microscopic examination of 19 carcinomas mostly revealed altered brush-border membrane features, irrespective of histological SI staining pattern. Brush-border enzyme activities of sucrase, alkaline phosphatase and maltase showed no difference between tumor specimens and peritumoral mucosa, but aminopeptidase was depressed in the former. Sucrase activity was extremely low (mean values 1.1 to 1.8 mU/mg protein) and rose only exceptionally to 17.5 mU/mg prot.
Int J Cancer 1989 Aug 15
PMID:Sucrase-isomaltase expression and enterocytic ultrastructure of human colorectal tumors. 275 30

The biochemical background of the intestinal side effects of cis-diammine-1,1-cyclobutane dicarboxylate platinum (II) (CBDCA) and cis-diisopropylamine-trans-dihydroxy-dichloro platinum (IV) (CHIP) was compared with those of cis-diamminedichloroplatinum (II) (CDDP). Biochemical investigations were carried out on mucosal cells isolated by a combined chemical-mechanical method from the total length of the small intestine. After treatment with single, equitoxic doses of Pt analogues, the activities of thymidine kinase (TK) EC 2.7.1.21, sucrase (SUC) EC 3.2.1.26, maltase (MAL) EC 3.2.1.20, and protein content showed dose-dependent decreases, whereas the activity of alkaline phosphatase (AP) EC 3.2.1.20 increased slightly. The nadir of enzyme activity changes occurred 24-48 h after treatment. For the regeneration of the mucosa more than 96 h was necessary. Of the platinum analogues studied, CHIP proved to be the most toxic to the small intestine. While the highest doses of CDDP and CBDCA (0.66 x LD50) caused significant but less than 50% decreases in TK, SUC, MAL, and protein content (PROT), the CHIP doses needed for 50% reduction were between 0.44-0.66 x LD50.
Cancer Chemother Pharmacol 1988
PMID:Comparison of intestinal toxic effects of platinum complexes: cisplatin (CDDP), carboplatin (CBDCA), and iproplatin (CHIP). 327 33


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