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

We are interested in the mechanism of cyclooxygenase-2 (Cox-2) regulation in colon cancer cells because this knowledge could provide insight into colon carcinogenesis and suggest ways to suppress Cox-2 expression in colon tumors. Studying the HT-29 colon cancer cell line as a model, we found that Cox-2 mRNA and protein levels were activated over 10-fold by the inflammatory cytokine tumor necrosis factor (TNF)-alpha. Moreover, we found that the histone deacetylase inhibitors butyrate and trichostatin A could block Cox-2 activation in a gene-specific manner. TNF-alpha and butyrate did not significantly affect Cox-2 promoter activity, mRNA stability, or negative regulation by the Cox-2 3'-untranslated RNA region. A nuclear run-on assay showed that TNF-alpha increased Cox-2 transcription, whereas butyrate was suppressive. Because butyrate has been reported to suppress polymerase elongation on the c-myc gene, we employed the chromatin immunoprecipitation assay to determine the influence of butyrate and trichostatin A on polymerase distribution on the Cox-2 gene. These data indicated that butyrate restricted polymerase elongation from exon 1 to 2 on both the c-myc and Cox-2 genes. We propose that histone deacetylases regulate a transcriptional block on the Cox-2 and c-myc genes and that this block may be a potential target for pharmacological intervention.
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PMID:Cyclooxygenase-2 regulation in colon cancer cells: modulation of RNA polymerase II elongation by histone deacetylase inhibitors. 1571 75

The short chain fatty acid (SCFA) butyrate (BA) and other histone deacetylase (HDAC) inhibitors can rapidly induce cell cycle arrest and differentation of colon cancer cell lines. We found that butyrate and the specific HDAC inhibitor trichostatin A (TSA) can reprogram the NF-(kappa)B response in colon cancer cells. Specifically, TNF-alpha activation is suppressed in butyrate-differentiated cells, whereas IL-1beta activation is largely unaffected. To gain insight into the relationship between butyrate-induced differentiation and NF-(kappa)B regulation, we determined the impact of butyrate on proteasome activity and subunit expression. Interestingly, butyrate and TSA reduced the cellular proteasome activity in colon cancer cell lines. The drop in proteasome activity results from the reduced expression of the catalytic beta-type subunits of the proteasome at both the protein and mRNA level. The selective impact of HDAC inhibitors on TNF-alpha-induced NF-(kappa)B activation appears to relate to the fact that the TNF-alpha-induced activation of NF-(kappa)B is mediated by the proteasome, whereas NF-kappaB activation by IL-1beta is largely proteasome-independent. These findings indicate that cellular differentation status and/or proliferative capacity can significantly impact proteasome activity and selectively alter NF-(kappa)B responses in colon cancer cells. This information may be useful for the further development and targeting of HDAC inhibitors as anti-neoplastic and anti-inflammatory agents.
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PMID:HDAC inhibition prevents NF-kappa B activation by suppressing proteasome activity: down-regulation of proteasome subunit expression stabilizes I kappa B alpha. 1595 Sep 52

Irinotecan hydrochloride shows much different responses in each patient, and it has severe adverse effects. Therefore, a sensitive marker for the side effect of irinotecan on immunotoxicity may be able to prevent the severe complications by the early detection. We have recently developed a method to assess the immunotoxicity by measuring the productivity of TNF-alpha from whole blood containing monocytes when stimulated by lipopolysaccharide. By using this method, the effects of continuous low-dose irinotecan therapy on immunotoxicity were assessed in 10 patients with advanced gastric or colon cancer. When compared this method with the others such as white blood cell count, lymphocyte blastoid transformation by phytohem agglutinin (PHA), and natural killer cell activity in terms of the sensitivity, immunotoxicity by this method was found earlier than the other methods. Because our original method is easy to perform and sensitive as compared to the conventional methods, it can be widely used as one of the laboratory tests useful for patients treated with immunosuppressive agents.
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PMID:[Assessment of immunotoxicity of irinotecan determined by the novel method, by which productivity of TNF-alpha from whole blood is stimulated by lipopolysaccharide]. 1610 27

A major component in green tea, epigallocatechin-3-gallate (EGCG), is reported to interfere with different steps of a number of inflammatory pathways. After oral administration, EGCG is retained in the gastrointestinal tract, where it is thought to exert preventive functions against inflammatory bowel disease and colon cancer. In this study, the human colon adenocarcinoma cell lines HT29 and T84 were used to investigate the effect of EGCG on intestinal inflammation. HT29 and T84 cells were stimulated with tumor necrosis factor (TNF)-alpha to induce the inflammatory condition and to trigger the inflammatory cascade in vitro and treated with EGCG to study its effect on inflammatory processes. The secretion of the chemokines interleukin (IL)-8, macrophage inflammatory protein (MIP)-3alpha, and prostaglandin E2 (PGE2) was determined by enzyme-linked immunosorbent assay. The gene expression level was measured by quantitative real-time polymerase chain reaction. Treatment of TNF-alpha-stimulated HT29 cells with EGCG dose-dependently inhibited the synthesis of IL-8, MIP-3alpha, and PGE2. Treatment with EGCG also inhibited the production of IL-8 and MIP-3alpha in TNF-alpha-stimulated T84 cells. Gene expression analysis in both HT29 and T84 cells revealed that EGCG down-regulates genes involved in inflammatory pathways. This study shows that EGCG acts broadly on the production of chemokines and PGE2 in the chemokine and eicosanoid pathways of colon epithelial cells. Therefore, EGCG might prove useful for the prevention and/or attenuation of colonic disorders.
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PMID:Epigallocatechin-3-gallate impairs chemokine production in human colon epithelial cell lines. 1612 9

In the tumor microenvironment, autocrine/paracrine loops of insulin-like growth factors (IGFs) contribute to cancer cell survival. However, we report here that IGF-I can send contradictory signals that interfere with cell death induced by different ligands of the tumor necrosis factor (TNF) superfamily. IGF-I protected human colon carcinoma cells from TNF-alpha-induced apoptosis, but it enhanced the apoptotic response to anti-Fas antibody and TNF-related apoptosis inducing ligand stimulation. This proapoptotic effect of IGF-I, observed in several but not all tested colon cancer cell lines, was mediated via the phosphatidylinositol 3'-kinase (PI3K)/Akt pathway. Furthermore, IGF-I receptors (IGF-IR) were located in and out of membrane lipid rafts and were tyrosine autophosphorylated in response to IGF-I. However, disruption of rafts by acute cholesterol depletion shifted IGF-IR to non-raft domains, abolished the IGF-I-mediated proapoptotic effect, and inhibited the IGF-I-dependent IRS-1 and Akt recruitment into and phosphorylation/activation within lipid rafts. Replenishing cell membranes with cholesterol reversed these effects. Activation of extracellular-regulated kinase-1/2 and p38 mitogen-activated protein kinase, which convey the IGF-I anti-apoptotic effect, occurred independently of lipid rafts. Thus, we propose that segregation of IGF-IR in and out of lipid rafts may dynamically regulate the pro- and anti-apoptotic effects of IGF-I on apoptosis induced by TNF superfamily members.
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PMID:Membrane rafts segregate pro- from anti-apoptotic insulin-like growth factor-I receptor signaling in colon carcinoma cells stimulated by members of the tumor necrosis factor superfamily. 1612 55

2'-Hydroxycinnamaldehyde (HCA) inhibits cell growth of several human cancer cells with unknown mechanisms. We investigated the inhibitory effect of HCA on TNF-alpha-induced cell growth and possible signal pathway in SW620 colon cancer cells. HCA inhibited TNF-alpha-induced SW620 colon cell growth in time- and dose-dependent manner through induction of apoptotic cell death. Parallel with inhibitory effect on cell growth, HCA dose dependency inhibited TNF-alpha-induced activation of NF-kappaB accompanied with inhibition of the translocation of p50. HCA also induced expression of caspase-3 and Bax, but decreased Bcl-2. HCA furthermore activated ERK pathway, and ERK inhibitor reversed inhibitory effect of HCA on cell growth and transcriptional activation of NF-kappaB. These results demonstrate that HCA inhibits cell growth through induction of apoptotic cell death by ERK pathway-dependent NF-kappaB inactivation.
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PMID:Induction of apoptotic cell death by 2'-hydroxycinnamaldehyde is involved with ERK-dependent inactivation of NF-kappaB in TNF-alpha-treated SW620 colon cancer cells. 1614 16

Intestinal epithelial cells not only present a physical barrier to bacteria but also participate actively in immune and inflammatory responses. The migration of epithelial cells from the crypt base to the surface is accompanied by a cellular differentiation that leads to important morphological and functional changes. It has been reported that the differentiation of colonic epithelial cells is associated with reduced interleukin (IL)-8 responses to IL-1beta. Although toll-like receptor 4 (TLR4) has been previously identified to be an important component of mucosal immunity to lipopolysaccharide (LPS) in the colon, little is known about the regulation of TLR4 in colonic epithelial cells during cellular differentiation. We investigated the effects of differentiation on LPS-induced IL-8 secretion and on the expression of TLR4. Differentiation was induced in colon cancer cell line HT-29 cells by butyrate treatment or by post-confluence culture and assessed by measuring alkaline phosphatase (AP) activity. IL-8 secretion was measured by ELISA, and TLR4 protein and mRNA expressions were followed by Western blot and RT-PCR, respectively. HT-29 cells were found to be dose-dependently responsive to LPS. AP activity increased in HT-29 cells by differentiation induced by treatment with butyrate or post-confluence culture. We found that IL-8 secretion induced by LPS was strongly attenuated in differentiated cells versus undifferentiated cells, and that cellular differentiation also attenuated TLR4 mRNA and protein expressions. Pretreating HT-29 cells with tumor necrosis factor (TNF)-alpha or interferon (INF)-gamma augmented LPS-induced IL-8 secretion and TLR4 expression. These TNF-alpha- or INF-gamma-induced augmentations of LPS response and TLR4 expression were all down-regulated by differentiation. Collectively, we conclude that cellular differentiation attenuates IL-8 secretion induced by LPS in HT-29 cells, and this attenuation is related with the down-regulation of TLR4 expression.
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PMID:Cellular differentiation-induced attenuation of LPS response in HT-29 cells is related to the down-regulation of TLR4 expression. 1620 85

During analysis of CD8 T cells derived from ascites of a colon cancer patient, we isolated a Vgamma9Vdelta2 T cell clone showing strong reactivity against autologous tumor cell lines. This clone killed a large fraction of allogeneic colon carcinoma and melanoma cell lines, but did not affect a normal colon cell line, colon fibroblasts, or melanocytes. Tumor cell recognition was TCR and NKG2D dependent and induced TNF-alpha and IFN-gamma secretion by the clone; accordingly, tumor targets expressed several NKG2D ligands, such as MHC class I chain-related gene A and UL16-binding protein molecules. Colon tumor recognition by Vgamma9Vdelta2 T cells was highly dependent on isopentenyl pyrophosphate production and ICAM-1 expression by target cells. Finally, similar reactivity patterns against colon carcinoma cell lines were observed using polyclonal Vgamma9Vdelta2 T cells of various origins, and Vgamma9Vdelta2 lymphocytes were present in the majority of colon tumor samples studied. Together, these results suggest that Vgamma9Vdelta2 T cells contribute to the natural immune surveillance against colon cancers. Therefore, this study provides a strong rationale for the use of Vgamma9Vdelta2 T cell agonists in immunotherapies targeting colon tumors.
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PMID:V gamma 9V delta 2 T cell response to colon carcinoma cells. 1621 Jun 56

We previously reported that the over-expression of hRFI, a protein preferentially expressed in the digestive tract regions of several cancers, exhibited a tendency to inhibit TNF-alpha induced apoptosis. In this study, we sought to determine the potential effect of hRFI expression on the sensitivity to 5-fluorouracil (5-FU) and/or other fluoropyrimidines. For the whole lysates of 8 colon cancer cell lines, we performed Western blotting with anti-hRFI antibody and analyzed the correlations between the expression level of hRFI and the cell lines' sensitivity to 5-FU induced apoptosis. Furthermore, for a tissue microarray consisting of 32 xenograft derived human cancer cell lines, we examined the expression levels of hRFI and survivin by immunohistochemical staining, and analyzed the correlations between the expression of each protein and the sensitivity to several chemotherapeutic agents in the xenografts examined. Both in colon cancer cell lines and in xenografts, the expression level of hRFI was correlated with resistance to 5-FU and its derivatives. This evidence suggests that hRFI may be a marker predicting the response to fluorouracil derived chemotherapeutic agents and that the reduction of the expression level of hRFI might improve the outcome of chemotherapy.
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PMID:High hRFI expression correlates with resistance to fluoropyrimidines in human colon cancer cell lines and in xenografts. 1627 May 26

The two-kringle domain of tissue-type plasminogen activator (TK1-2) has been identified as a novel angiogenesis inhibitor. In the previous study, purified Pichia-derived TK1-2 has been shown to suppress in vivo growth of human lung and colon cancer cells. Here, we demonstrate that E. coli-derived non-glycosylated TK1-2 suppresses tumor growth more potently than Pichia-derived TK1-2 and prolongs the survival of tumor bearing mice. The recombinant TK1-2 prepared through E. coli expression, His-tag affinity chromatography and in vitro refolding was injected intraperitoneally once daily into nude mice 7 days after subcutaneous implantation with PC14 lung cancer cells (n=10). Measurement of tumor volumes indicated that low-dose TK1-2 treatment (10 mg/kg) suppressed tumor growth by approximately 85.2% (p<0.01), while high-dose TK1-2 treatment (50 mg/kg) even more potently inhibited tumor growth (>93.8%) (p<0.005). Treatment of TK1-2 also prolonged the survival of tumor-bearing mice in a dose-dependent fashion. In an independent HCT116 xenograft model, E. coli-derived TK1-2 was more effective in suppressing tumor growth than Pichia-derived TK1-2. Immunohistochemical analysis of tumor tissue also revealed that the expression of VEGF, SMA-alpha, TNF-alpha and angiogenin was less positive in the E. coli-derived TK1-2-treated group than in the Pichia-derived TK1-2-treated group. These results suggest that E. coli-derived refolded, non-glycosylated TK1-2 can be used more effectively as an anti-cancer agent.
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PMID:Potent anti-tumor and prolonged survival effects of E. coli-derived non-glycosylated kringle domain of tissue-type plasminogen activator. 1639 90


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