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

One of the most promising strategies in colon cancer therapy is the sensitization of cancer cells to natural proapoptotic cytokines, such as death ligands and interferons, which are able to eliminate abnormal cells. The investigation of mechanisms determining the immune escape of cancer cells revealed the presence of antiapoptotic proteins, such as cFLIP, which inhibit cell death signal transduction. Numerous studies showed that the use of different metabolic inhibitors, such as cycloheximide (CHX), reduces the cFLIP protein level, thus restoring the susceptibility to TNF-alpha-induced apoptosis. However, high non-specific toxicity of CHX excludes the clinical use of this substance. The current efforts are focused on identification of bioactive compounds which could safely support immunotherapy. The review presents in vitro and in vivo evidence that butyrate (Bt), fatty acid produced in colon during fermentation process and parthenolide (PN), sesquiterpene lactone isolated from Tanacetum parthenium specifically affect different cancer cells. Among described various molecular mechanisms of Bt and PN action, one reduces the level of antiapoptotic proteins. This paper clearly demonstrates that bioactive compounds, especially combined with immune cytokines could be seriously considered as an alternative for routine colon anti-cancer therapy.
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PMID:Antiapoptotic proteins as targets for bioactive compounds. 1788 39

COLO 205 colon adenocarcinoma cells are highly resistant to extrinsic apoptosis induced by immunomodulatory cytokines. One of the antiapoptotic mechanisms is the expression of cFLIP protein, which inhibits TNF-alpha-induced cell death. The use of metabolic inhibitors, such as sodium butyrate (NaBt), the potent repressor of histone deacetylase, sensitizes tumor cells to TNF-alpha-mediated apoptosis. The Western-blot analysis revealed that in COLO 205 cells the susceptibility to apoptogenic stimuli results from time-dependent reduction in cFLIP(L) protein assembled with DISC complex. At the same time, the level of transmembrane TNF-alpha receptor 1 (TNF-R1) was elevated which is consistent with the exaggerated rate of cell death. Since preincubation of COLO 205 cells with N-acetyl-L-cysteine (NAC), or sodium ascorbate (ASC) did not protect cells from combined NaBt- and TNF-alpha-induced apoptosis, we concluded that deletion of cancer cells is not evoked by oxidative stress. Our results suggest that the combination of TNF-alpha with NaBt targets antiapoptotic protein(s) and may provide efficient and non-toxic treatment of colon cancer.
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PMID:Sodium butyrate-dependent sensitization of human colon adenocarcinoma COLO 205 cells to TNF-alpha-induced apoptosis. 1790 92

Recent studies indicate that secondary bile acids promote colon cancer cell proliferation but their role in maintaining cell survival has not been explored. We found that deoxycholyltaurine (DCT) markedly attenuated both unstimulated and TNF-alpha-stimulated programmed cell death in colon cancer cells by a phosphatidylinositol 3-kinase (PI3K)-dependent mechanism. To examine the role of bile acids and PI3K signaling in maintaining colon cancer cell survival, we explored the role of signaling downstream of bile acid-induced activation of the epidermal growth factor receptor (EGFR) in regulating both apoptosis and proliferation of HT-29 and H508 human colon cancer cells. DCT caused dose- and time-dependent Akt (Ser(473)) phosphorylation, a commonly used marker of activated PI3K/Akt signaling. Both EGFR kinase and PI3K inhibitors attenuated DCT-induced Akt phosphorylation and Akt activation, as demonstrated by reduced phosphorylation of a GSK-3-paramyosin substrate. Transfection of HT-29 cells with kinase-dead EGFR (K721M) reduced DCT-induced Akt phosphorylation. In HT-29 cells, EGFR and PI3K inhibitors as well as transfection with dominant negative AKT attenuated DCT-induced cell proliferation. DCT-induced PI3K/Akt activation resulted in downstream phosphorylation of GSK-3 (Ser(21/9)) and BAD (Ser(136)), and nuclear translocation (activation) of NF-kappaB, thereby confirming that DCT-induced activation of PI3K/Akt signaling regulates both proproliferative and prosurvival signals. Collectively, these results indicate that DCT-induced activation of post-EGFR PI3K/Akt signaling stimulates both colon cancer cell survival and proliferation.
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PMID:Deoxycholyltaurine rescues human colon cancer cells from apoptosis by activating EGFR-dependent PI3K/Akt signaling. 1806 5

The expression of the genes coding TNFalpha and TNF RII receptors (TNF RII: TNFR2 membrane and soluble domain, TNFR2/R7 soluble domain) was analysed in colon cancer at the II and III stage of disease, by estimation of mRNA expression. The study included 80 patients with histopathologically confirmed adenocarcinoma. The number of TNFalpha mRNA, TNFR2 mRNA and TNFR2/R7 mRNA copies were estimated in tumour and healthy tissue. The highest number of mRNA TNF-alpha copies were investigated in all samples of tissue and independently of the stage of disease. Simultaneously, we noticed the largest number of mRNA copies for TNFalpha and TNF R2/R7 in healthy cells at stage III of the disease. It is possible to draw a hypothetical line separating the anti-cancer activity of TNFalpha and its influence on cancer progression.
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PMID:Genetic disregulation of TNF alpha and TNF alpha type II receptors in colon cancer at the II and III stage of disease. 1808 49

The effect of chitosan oligosaccharide (COS, 1 kDa <MW<3 kDa) on proinflammatory cytokines-induced nitric oxide (NO) production and invasiveness of human colorectal adenocarcinoma HT-29 cells was investigated. COS (0.1-5mg/ ml) suppressed the NO production induced by proinflammatory cytokines (100 U/ml IFN-gamma, 10 ng/ml IL-1alpha, and 25 ng/ml TNF-alpha) in HT-29 cells. Inducible nitric oxide synthase (iNOS) expression induced by these cytokines was inhibited by COS. COS pretreatment inhibited the invasiveness of cytokines-treated HT-29 cells through Matrigel-coated membrane in a dose-dependent manner. COS also inhibited cytokines-induced matrix metalloproteinase (MMP)-2 activity. This study shows that proinflammatory cytokines induce NO production, iNOS expression, and invasiveness of human colorectal adenocarcinoma HT-29 cells. COS pretreatment inhibited cytokines-mediated NO production, iNOS expression, and invasiveness of HT-29 cells. These results provide sufficient information for the further development of COS as an antitumor metastatic agent for the treatment of colon cancer.
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PMID:Inhibition of proinflammatory cytokine-induced invasiveness of HT-29 cells by chitosan oligosaccharide. 1816 53

Chronic inflammatory disorders are often associated with an increased cancer risk. A particularly striking example of the chronic inflammation-cancer link is seen in inflammatory bowel disease, in which chronic colitis or persistent inflammation in the colon is associated with elevated risk of colorectal cancer. Animal models exploring the mechanisms by which inflammation increases the risk of colon cancer have shown that inflammatory cells, through the effects of the cytokines they produce, have a major role in promoting neoplastic transformation. In this issue of the JCI, Popivanova and colleagues demonstrate that TNF-alpha, through its effects on the immune system, plays a critical role in promoting neoplastic transformation in this setting (see the related article beginning on page 560). Importantly, the study also provides evidence that anti-TNF-alpha therapies, which are currently in clinical use, may interrupt the process.
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PMID:Colitis and cancer: a tale of inflammatory cells and their cytokines. 1821 94

The inflammatory bowel disease ulcerative colitis (UC) frequently progresses to colon cancer. To understand the mechanisms by which UC patients develop colon carcinomas, we used a mouse model of the disease whereby administration of azoxymethane (AOM) followed by repeated dextran sulfate sodium (DSS) ingestion causes severe colonic inflammation and the subsequent development of multiple tumors. We found that treating WT mice with AOM and DSS increased TNF-alpha expression and the number of infiltrating leukocytes expressing its major receptor, p55 (TNF-Rp55), in the lamina propria and submucosal regions of the colon. This was followed by the development of multiple colonic tumors. Mice lacking TNF-Rp55 and treated with AOM and DSS showed reduced mucosal damage, reduced infiltration of macrophages and neutrophils, and attenuated subsequent tumor formation. WT mice transplanted with TNF-Rp55-deficient bone marrow also developed significantly fewer tumors after AOM and DSS treatment than either WT mice or TNF-Rp55-deficient mice transplanted with WT bone marrow. Furthermore, administration of etanercept, a specific antagonist of TNF-alpha, to WT mice after treatment with AOM and DSS markedly reduced the number and size of tumors and reduced colonic infiltration by neutrophils and macrophages. These observations identify TNF-alpha as a crucial mediator of the initiation and progression of colitis-associated colon carcinogenesis and suggest that targeting TNF-alpha may be useful in treating colon cancer in individuals with UC.
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PMID:Blocking TNF-alpha in mice reduces colorectal carcinogenesis associated with chronic colitis. 1821 90

Biphenolic components in Magnolia obovata including magnolol and honokiol have shown several pharmacological activities such as anti-tumor, anti-oxidant and anti-inflammatory effects. Previously in cultured macrophage Raw264.7 cells and fibroblast, we found that obovatol, an active compound isolated from M. obovata inhibited NF-kappaB activity which has been known to be a significant transcriptional factor to control of cancer cell growth. We investigated here whether obovatol could inhibit NF-kappaB activity, and thereby inhibit cancer cell growth in prostate (LNCaP and PC-3) and colon cancer (SW620 and HCT116) cells. Treatment of obovatol (10, 15, 20, 25 microM) inhibits cancer cell growth in the absence or the presence of tumor necrosis factor-alpha (TNF-alpha , 10 ng/ml) and tetradecanoyl phorbol acetate (TPA 10 or 50 nM) in a concentration-dependent manner through induction of apoptotic cell death. Cytotoxic activity was not observed in normal cells with up to 50 muM obovatol. It was also found that obovatol inhibited TNF-alpha and TPA-induced transcriptional and DNA binding activities of NF-kappaB. In further study, obovatol decreased translocation p65 and p50 into nucleus via decrease of phosphorylation of IkappaB. Correlated well with the induction of apoptosis, obovatol increased the expression of the apoptotic genes; Bax, caspase-3, caspase-9, whereas inhibited expression of anti-apoptotic genes; Bcl-2, inhibitor of apoptosis protein (IAP-1) and X chromosome IAP (XIAP) as well as the cell proliferation marker genes; Cox-2, c-Fos, c-Jun and cyclin D1. These results suggest that obovatol inhibits prostate and colon cancer cell growth via induction of apoptotic cell death, and that inhibition of NF-kappaB may be a significant as its action mechanism.
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PMID:Growth inhibitory effects of obovatol through induction of apoptotic cell death in prostate and colon cancer by blocking of NF-kappaB. 1824 58

Inositol hexaphosphate (IP6, phytic acid) is a naturally occurring carbohydrate abundantly present in high-fiber diets and it is also contained in almost all mammalian cells. It plays an important role in signal transduction, cell proliferation and differentiation. Some natural substances have been shown to elicit an impact on the expression of TNF-alpha and its receptors in cancer cells. TNF-alpha represents cytokine very often deregulated at the level of both gene expression and signal transmission through TNF-alpha receptors (TNFRI and TNFRII). The aim of the present study was to analyze the IP6 influence on the transcription of genes coding for TNF-alpha and its receptors in human colon cancer cells line Caco-2 Real-time QRT-PCR based on TaqMan methodology was applied to analyze quantitatively the transcript levels of these genes. Three concentrations (1, 2.5 and 5 mM) of IP6 were used for Caco-2 cells stimulation for 1, 6, 12 and 24 h. The results showed that IP6 modulated the expression of the listed genes at transcription level in a dose and time dependent manner. The enhanced TNFRI and decreased TNF-alpha and TNFRII transcription in Caco-2 cells stimulated for 12 h with IP6 seems to be the presumptive evidence for anti-inflammatory and antitumor activity of IP6.
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PMID:The influence of phytic acid on TNF-alpha and its receptors genes' expression in colon cancer Caco-2 cells. 1853 77

We assessed the immunological status of stage III and IV head and neck squamous cell carcinoma (HNSCC) patients and age-matched healthy individuals. In HNSCC patients, the total leukocyte count was lower and the proliferating ability of PBMCs against phytohemagglutinin (PHA) was significantly downregulated. These cells showed lower expression of the early activation marker CD69. Within this PBMC population, the proportion of CD4+, CD8+ T cells, CD3- CD56+, CD16+ NK cells and CD3+ CD56+ NK-T cells was seriously downregulated. However, the proportion of CD4+ CD25+ Foxp3+ regulatory T cells having suppressor function was upregulated. Other immune cells, like CD14+ monocytes/macrophages and CD20+ B cells, were also fewer in number, although this difference was not statistically significant. Assessment of the cytokine secretory status of PBMCs revealed suppressed levels of Th1 cytokines (IFN-gamma, IL-12 and TNF-alpha) and elevated secretion of Th2 cytokines (IL-4 and IL-10) for HNSCC PBMCs whereas just the opposite was seen for PBMCs from healthy individuals. Dysregulation in the profile of immunocompetent cells and cytokine secretion was reflected in the suppressed cytotoxic function of HNSCC PBMCs, as tested on KB (oral cancer), MCF7 (breast cancer), COLO205 (colon cancer), Jurkat (T cell leukemia), K562 (erythroleukemia) and U937 (monocytic lymphoma) cell lines. The observed decreased cytotoxicity of HNSCC PBMCs may be due to the downregulated expression of cytotoxic molecules (perforin, granzymeB and FasL) in HNSCC PBMCs. Assessment of the extent of immune dysfunction might help design immunotherapeutic protocols by incorporating any agent having immunomodulatory function.
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PMID:Dysregulation in immune functions is reflected in tumor cell cytotoxicity by peripheral blood mononuclear cells from head and neck squamous cell carcinoma patients. 1854 33


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