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Query: UMLS:C0699790 (colon cancer)
 28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The complete sequence of the 6 kb cDNA and the 5' genomic structure are reported for the gene coding for the human intestinal brush border hydrolase sucrase-isomaltase. The human sucrase-isomaltase cDNA shows a high level of identity (83%) with that of the rabbit enzyme, indicating that the protein shares the same structural domains in both species. In addition to the previously reported homology with lysosomal alpha-glucosidase, the sucrase and isomaltase subunits also appear to be homologous to a yeast glucoamylase. A 14 kb human genomic clone has been isolated which includes the first three exons and the first two introns of the gene, as well as 9.5 kb 5' to the major start site of transcription. The first exon comprises 62 bp of untranslated sequence and the second starts exactly at the initiation ATG codon. Typical CAAT and TATA boxes are seen upstream of the first exon. A genetic polymorphism is described which involves a PstI site in the second intron. Southern blotting, sequencing and mRNA studies indicate that the structures of the sucrase-isomaltase gene and its mRNA are unaltered in the two human colon cancer cell lines Caco-2 and HT-29 in comparison with normal human small intestine.
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PMID:Sequence of the complete cDNA and the 5' structure of the human sucrase-isomaltase gene. Possible homology with a yeast glucoamylase. 135 58

The human colon cancer cell line Caco-2 undergoes spontaneous enterocytic differentiation during growth, and expresses a number of brush-border-membrane-associated hydrolases typical of a differentiated phenotype. Among these are alkaline phosphatase, dipeptidyl peptidase IV and sucrase-isomaltase (sucrase, EC 3.2.1.48). Neutral endopeptidase 24.11 [EC 3.4.24.11, neprilysin (NEP)] is another abundant protease of normal enterocytes but its presence in Caco-2 cells has not been fully documented yet. In this paper, we show that Caco-2 cell extracts hydrolyse tritiated [D-Ala2Leu5]enkephalin with a Km of 180 microM, very close to the value obtained for the NEP present in the rabbit kidney (118 microM). Western-blot analysis of brush-border membranes purified from post-confluent cells revealed a protein with an apparent molecular mass of 94000 Da similar to that of the rabbit kidney NEP. The amount of enzyme in cell extracts increased as a function of the age of the culture, indicating that NEP expression is correlated with the degree of cell differentiation as is also the case for sucrase and dipeptidylpeptidase IV (DPP-IV). Binding of a radiolabelled antibody to Caco-2 cell monolayers grown on semi-permeable filters indicated that 95% of NEP molecules present at the cell surface are on the apical side. Immunocytochemical and flow cytometric analysis of intact and permeabilized cells were also used to investigate the presence of NEP and DPP-IV at the surface of Caco-2 cells. Whereas DPP-IV staining appeared to be homogeneous throughout the entire cell population, NEP-related fluorescence exhibited a bimodal distribution which indicates an uneven expression of the protein at the cell surface. Permeabilization of monolayers with saponin before staining restored a labelling pattern for NEP similar to the one obtained for DPP-IV. This suggests that although DPP-IV and NEP follow similar patterns of expression when enzymic activities are measured on whole-cell extracts, targeting of these brush-border proteins to the cell surface appears to be regulated in different ways.
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PMID:Polarized distribution of neutral endopeptidase 24.11 at the cell surface of cultured human intestinal epithelial Caco-2 cells. 136 26

Glucose starvation has been widely used to select differentiated subpopulations from the heterogenous human colon cancer cell line HT29. We observed that the important cell loss elicited by culturing these cells in glucose-free medium could be limited when type I collagen gel was used as substratum instead of conventional plastic support. We took advantage of this property to develop a new protocol, which combined glucose starvation and culture on collagen gels, for cloning HT29 cells. Using this procedure we have isolated four clones that were characterized on the basis of morphological (optical and transmission electron microscopy), electrophysiological (determination of transepithelial electrical parameters) and biochemical (detection of villin, sucrase-isomaltase and carcinoembryonic antigen) criteria. These four clones expressed different patterns of enterocytic differentiation regarding to these criteria. These results confirmed the heterogeneity of the HT29 cell line. One of these clones, HT29-A7, which displayed numerous intercellular cysts that disappeared at confluency, appears as a complementary model in the study of epithelial biogenesis.
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PMID:Combination of culture on collagen gels and glucose starvation for cloning human colon cancer cells. Obtention of clones exhibiting different patterns of enterocytic differentiation. 136 54

To gain further insight on the mosaic expression of specific functional intestinal markers (such as sucrase-isomaltase) in postconfluent Caco-2 cells, a human colon cancer cell line unique in its property to differentiate in vitro into a mature enterocyte-like cell type, a comparative study was undertaken to examine the morphological and functional differentiation of Caco-2 cells at various culture stages. The observations clearly indicate that Caco-2 cells can exist only in three different states in culture: homogeneously undifferentiated (at subconfluence), heterogeneously polarized and differentiated (between 0 and 20 days after confluence), and homogeneously polarized and differentiated (after 30 days). Indeed, in the intermediate state, a strong discrepancy is found among adjacent differentiating cells throughout the monolayer relative to sucrase-isomaltase expression as well as to cell morphology and brush border organization. Back-scattered electron imaging analysis showed a lack of correlation between these parameters at the cellular level. These observations indicate that morphological and functional differentiations of Caco-2 cells progress concomitantly according to a transient mosaic pattern, thus providing evidence that these two processes are not coupled.
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PMID:Transient mosaic patterns of morphological and functional differentiation in the Caco-2 cell line. 163 60

The purpose of this work was to investigate whether sucrase-isomaltase from enterocyte-like differentiated human colon carcinoma cell lines carries blood group antigens of the ABH system. Six cultured lines of blood group A (HT-29, SW-480, Co-115) or O phenotype (Caco-2, HRT-18, HCT-8R) were studied. Only HT-29 cells grown in the absence of glucose (HT-29 Glc-) and Caco-2 cells express an enterocytic differentiation with the presence of sucrase-isomaltase on the apical surface of the cells. Binding of anti-A antibodies to HT-29 Glc- and of UEA-I to Caco-2 cells gave the same apical immunofluorescence pattern of staining as did anti-sucrase-isomaltase antibodies, whereas only a membrane binding was observed in nondifferentiated cells. Sucrase-isomaltase immunoisolated from HT-29 Glc- and Caco-2 cells reacted with anti-A antibodies and Ulex europaeus agglutinin-I (UEA-I), respectively, at sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot. Immunoprecipitation of solubilized brush border-enriched fractions from the same cells with UEA-I or anti-A antibodies resulted in an inhibition of sucrase activity which reached congruent to 80% for Caco-2 cells with UEA-I and approximately equal to 50% for HT-29 cells with anti-A antibodies. Similar results were obtained in the corresponding tumors in nude mice: anti-A antibodies in HT-29 and UEA-I in Caco-2 tumors bound to the same apical structures as did anti-sucrase-isomaltase antibodies; sucrase-isomaltase immunoisolated from the tumors bound anti-A antibodies (HT-29) or UEA-I (Caco-2). These results support the hypothesis that sucrase-isomaltase from enterocyte-like differentiated human colon cancer cells carries blood group antigens of the ABH system. These findings suggest that colon cancers which have been shown to display an apical pattern of expression of ABH antigens should be screened for their possible enterocytic differentiation.
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PMID:A and H blood group antigens as markers of sucrase-isomaltase from the enterocyte-like differentiated human colon carcinoma cell lines HT-29 and Caco-2. 243 17

The human colon cancer line Caco-2 exhibits after confluency a concomitant increase of glycogen accumulation and an enterocytic differentiation. The purpose of this work was to investigate whether forskolin (FK), an activator of adenylate cyclase, would induce a permanent glycogenolysis and, if so, whether it would result in modifications of the differentiation pattern of the cells. FK activates adenylate cyclase in Caco-2 cells with an ED50 of 7 X 10(-6)M. Three different treatment protocols with FK (10(-5)M) were applied: 1) the cells were treated during all the time in culture (20 days); 2) the treatment was started after confluency; 3) the treatment was interrupted after confluency. The presence of FK results in a permanent stimulation of cAMP accumulation (10 to 20 fold the basal values) and in a permanently reduced glycogen content (30 or 50% of the control values). The rates of glucose consumption are increased three and five fold in protocols 1 and 3 respectively. These metabolic changes are associated with morphological changes (tightening of the intercellular spaces and shortening of the brush border microvilli) and with a dual inhibition of the activities of brush border hydrolases: a) an inhibition of the post-confluent increase of activity of sucrase, aminopeptidase N and alkaline phosphatase in the brush border enriched fraction; b) an inhibition of the post-confluent increase of activity of sucrase in the cell homogenate. A comparison of the results obtained in each protocol shows that the morphological modifications and the decrease of the enzyme activities in the brush border fraction are regularly associated with an increased cAMP accumulation, whereas the inhibition of the differentiation of sucrase is a direct consequence of the increase in glucose consumption and decrease in glycogen stores.
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PMID:Enterocytic differentiation and glucose utilization in the human colon tumor cell line Caco-2: modulation by forskolin. 298 31

Studies on the regulation of the enterocytic differentiation of the human colon cancer cell line HT-29, which is differentiated in the absence (Glc-) but not in the presence of glucose (Glc+), have recently shown that the post-translational processing of sucrase-isomaltase and particularly its glycosylation vary as a function of cell differentiation (Trugnan G., Rousset, M., Chantret, I., Barbat, A., and Zweibaum, A. (1987) J. Cell Biol. 104, 1199-1205). Other studies indicate that in undifferentiated HT-29 Glc+ cells there is an accumulation of UDP-N-acetylhexosamine, which is involved in the glycosylation process (Wice, B. M., Trugnan, G., Pinto, M., Rousset, M., Chevalier, G., Dussaulx, E., Lacroix, B., and Zweibaum, A. (1985) J. Biol. Chem. 260, 139-146). The purpose of the present work is to investigate whether an overall alteration of protein glycosylation is associated with the inability of HT-29 cells to differentiate. At least three alterations are detected: (i) after a 10-min pulse, the incorporation of D-[2-3H]mannose in undifferentiated cells is severely reduced, compared to differentiated cells. (ii) After a 24-h period of labeling with D-[2-3H]mannose, undifferentiated cells accumulate more than 60% of the radioactivity in the high mannose glycopeptides, whereas differentiated HT-29 Glc- cells accumulate only 38%. (iii) The analysis of the high mannose oligosaccharides transferred "en bloc" from the lipid precursor shows that Man9,8-GlcNAc2 species accumulate in undifferentiated cells, whereas no such accumulation can be detected in differentiated cells. This glycosylation pattern is consistent with an impairment of the trimming of high mannose into complex glycans. It is concluded that N-glycan processing is correlated with the state of enterocytic differentiation of HT-29 cells.
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PMID:The processing of asparagine-linked oligosaccharides in HT-29 cells is a function of their state of enterocytic differentiation. An accumulation of Man9,8-GlcNAc2-Asn species is indicative of an impaired N-glycan trimming in undifferentiated cells. 336 Jul 73

The incidence, distribution, size, and histopathology of small and large bowel tumors induced by parenteral administration of 1,2-dimethylhydrazine were examined in rats given 1% or 2% sodium butyrate dissolved in drinking water. Although previous in vitro reports on colon cancer cell lines have suggested that sodium butyrate might have a role to play as a chemotherapeutic "differentiating agent," the results of this in vivo study indicate that sodium butyrate treatment enhanced the development of colonic neoplasia and was associated with increased fecal butyric acid concentrations. In contrast, no changes were seen in the incidence of small bowel tumors, luminal butyric acid concentrations, mucosal morphology, or brush-border enzyme activities (i.e., sucrase, alkaline phosphatase). This study suggests that dietary butyrate has an important, possibly indirect, regulatory role in carcinogenesis associated with an experimental animal model of colonic neoplasia.
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PMID:Effects of differing concentrations of sodium butyrate on 1,2-dimethylhydrazine-induced rat intestinal neoplasia. 373 64

In order to study the effect of glucose on the differentiation of cultured human colon cancer cells, a subpopulation of HT-29 cells was selected for its capacity to grow in the total absence of sugar. These cells (Glc-cells) exhibit, after confluency, an enterocytic differentiation, in contrast to cells grown with glucose (Glc+ cells), which always remain undifferentiated. The differentiation is characterized by a polarization of the cell layer with apical brush borders and tight junctions, and by the presence of sucrase-isomaltase. The differentiation of Glc- cells is reversible: the addition of glucose to postconfluent cultures of Glc- cells results in an inhibiting effect on the expression of sucrase-isomaltase; switching growing cultures of Glc- cells to the Glc+ medium for several passages results in a progressive reversion to the undifferentiated state, which is completed after seven passages. The dedifferentiation process is associated with a parallel, passage-related, increase in the rates of glucose consumption and lactic acid production, and decreases of intracellular glycogen content, which return to the values of the undifferentiated original Glc+ cells. The values of these metabolic parameters are correlated, at each passage, with the degree of dedifferentiation of the cells. When these dedifferentiated cells, after having been cultured in Glc+ medium for 20 passages, are switched back to the Glc- medium, they readily grow without mortality, and reexpress the same enterocytic differentiation as the parent Glc- cells. These results show that the capacity of this subpopulation to grow and differentiate in the absence of sugar is a stable characteristic. They further suggest that glucose metabolism interferes with the program of differentiation of HT-29 cells.
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PMID:Enterocytic differentiation of a subpopulation of the human colon tumor cell line HT-29 selected for growth in sugar-free medium and its inhibition by glucose. 388 Jul 64

Epidemiological and in vivo and in vitro experimental studies have suggested that fermented milks may interfere with the emergence and/or the development of colon cancer. The results, however, remain inconclusive. This prompted us to develop a new approach based on the use of HT-29, a cultured human colon cancer cell line, to study at the cellular level the effect of fermented milks on colon cancer cell growth and differentiation characteristics. Undifferentiated HT-29 cells have been grown in the continuous presence of milks fermented by one of the following bacterial populations: Lactobacillus helveticus, Bifidobacterium, L.acidophilus or a mix of Streptococcus thermophilus and L. bulgaricus. Penicillin G was added to the cell culture medium, resulting in a complete blockade of bacterial growth without significant effect on bacterial viability. One out of the four bacteria species studied, namely L.acidophilus, was without effect on both cell growth and differentiation. The three other bacterial strains induced a significant, although variable, reduction in the growth rate of HT-29 cells, which resulted in a 10-50% decrease in the cell number at steady-state (i.e. at cell confluency). The most efficient strains in lowering the HT-29 growth rate were L. helveticus and Bifidobacterium. Concomitantly, the specific activities of dipeptidyl peptidase IV (DPP IV), a sensitive and specific marker of HT-29 cell differentiation, and that of three other brush border enzymes (sucrase, aminopeptidase N and alkaline phosphatase) were significantly increased, thus suggesting that these cells may have entered a differentiation process. Altogether, these results indicate that the use of cultured colon cancer cells may be a useful tool to further study the effect of fermented milks on colon cancer and that bacterial strains may exert a different and specific effect on cancer cell growth and differentiation when used in fermented milk products.
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PMID:Use of HT-29, a cultured human colon cancer cell line, to study the effect of fermented milks on colon cancer cell growth and differentiation. 785 55


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