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

We investigated the role of hepatocyte-derived soluble growth factors on cell proliferation and expression of growth factors and their receptors in four colon cancer cell lines of varying liver-colonizing ability. Cocultures of hepatocytes and colon cells and cultures of colon cells with hepatocyte-conditioned medium resulted in growth inhibition of both weakly and strongly metastatic cell lines. Growth inhibition was accompanied by a reduced expression of erb-B2 in the colon cells after 4 days in the presence of hepatocytes. In LS174T and LiM6 cells, there was a dramatic reduction in heregulin-alpha levels in the presence of hepatocytes. Interestingly, after 2 days in culture, hepatocyte-derived soluble factors increased the mRNA levels for the EGF family members amphiregulin and cripto. These studies show an inhibitory effect of hepatocyte-derived soluble factors on the proliferation of colon cell lines, mediated in part by changes in the expression of autocrine growth factors and receptors of the EGF and heregulin family.
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PMID:Hepatocyte-derived soluble factors regulate proliferation and autocrine growth factor expression in colon cancer cell lines of varying liver-colonizing capability. 1086 12

NHE3 is an intestinal epithelial isoform Na+/H+ exchanger that is present in the brush border of small intestinal, colonic, and gallbladder Na(+)-absorbing epithelial cells. NHE3 is acutely up- and downregulated in response to some G protein-linked receptors, tyrosine kinase receptors, and protein kinases when studied in intact ileum, when stably expressed in PS120 fibroblasts, and in the few studies reported in the human colon cancer cell line Caco-2. In most cases this is due to changes in Vmax of NHE3, although in response to cAMP and squalamine there are also changes in the K'(H+)i of the exchanger. The mechanism of the Vmax regulation as shown by cell surface biotinylation and confocal microscopy in Caco-2 cells and biotinylation in PS120 cells involves changes in the amount of NHE3 on the plasma membrane. In addition, in some cases there are also changes in turnover number of the exchanger. In some cases, the change in amount of NHE3 in the plasma membrane is associated with a change in the amount of plasma membrane. A combination of biochemical studies and transport/inhibitor studies in intact ileum and Caco-2 cells demonstrated that the increase in brush border Na+/H+ exchange caused by acute exposure to EGF was mediated by PI 3-kinase. PI 3-kinase was also involved in FGF stimulation of NHE3 expressed in fibroblasts. Thus, NHE3 is another example of a transport protein that is acutely regulated in part by changing the amount of the transporter on the plasma membrane by a process that appears to involve vesicle trafficking and also to involve changes in turnover number.
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PMID:Short-term regulation of NHE3 by EGF and protein kinase C but not protein kinase A involves vesicle trafficking in epithelial cells and fibroblasts. 1119 92

Membrane mucins have several functions in epithelial cells including cytoprotection, extravasation during metastases, maintenance of luminal structure, and signal transduction. In this paper we describe a large membrane mucin expressed in the normal intestine. This novel mucin, designated MUC17, contains an extended, repetitive extracellular glycosylation domain and a carboxyl terminus with two EGF-like domains, a SEA module domain, a transmembrane domain, and a cytoplasmic domain with potential serine and tyrosine phosphorylation sites. RNA blot analysis and in situ hybridization indicates that MUC17 is expressed in select pancreatic and colon cancer cell lines and in intestinal absorptive cells. Radiation hybrid mapping localized MUC17 to chromosome 7q22 where it resides in close proximity with three other membrane mucin genes, MUC3A, MUC3B, and MUC12. Thus, these membrane mucins reside together in a gene cluster, but are expressed in different tissues and are likely to have different functions as well.
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PMID:MUC17, a novel membrane-tethered mucin. 1185 12

Two thousand and three was a particularly dense year for publications and communications on therapy for colon cancer summarizing the real advance performed in this field. The last ten years allowed a rapid evolution for colon chemotherapy with a switch from 5-FU modulated by leucovorin to poly-chemotherapy (fluoropyrimidines with oxaliplatin or irinotecan) integrated into therapeutic strategies, where surgery had a place more and more important in metastatic patients. In correlation with these advances, median survival of patient with metastatic colorectal cancer is between 17 and 22 months. Targeted therapeutics with monoclonal antibody such as EGF inhibitors (cetuximab) or VEGF inhibitors (bevacizumab) had for the first time demonstrated efficacy with encouraging results in randomised trials. In adjuvant situation, LV5FU2 is less toxic than monthly FUFOL and no statistically significant difference could be detected in disease-free or overall survival between the two schedules. Oxaliplatin combined with 5 fluorouracil and leucovorin (FOLFOX4) is the first combination to demonstrate significant superiority over 5 fluorouracil and leucovorin in adjuvant treatment of colorectal cancer. Fluorouracil-based adjuvant chemotherapy benefited to patients with stage II or III colon cancer with microsatellite-stable tumours or tumour exhibiting low-frequency microsatellite instability but may be not those with tumours exhibiting high-frequency microsatellite instability (MSI). These data need to be confirmed by prospective studies before changing our therapeutic references. The number of lymph nodes analyzed for colon cancer staging is itself a prognostic variable on outcome. Laparoscopic surgery of colon cancer is demonstrated as a feasible and safe procedure. Shrinkage of tumours after administration of preoperative chemotherapy and availability of ablative techniques (radiofrequency and cryotherapy) now allow to treat with curative intent metastases initially considered as non-resectable.
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PMID:[Colon cancer: what is new in 2004?]. 1497 8

Epidermal growth factor receptor (EGFR) is commonly overexpressed in a number of epithelial malignancies and is often associated with an aggressive phenotype [e.g., non-small cell lung cancer (NSCLC) and bladder cancer]. EGFR is present in over 50% of cases of NSCLC, head and neck squamous cell carcinomas (HNSCC) and colon cancer. Several EGFR-targeting agents have been recently developed (C225, ABX-EGF, E7.6.3, EMD 55900, ICR62, ZD1839, CP358774, PD168393, CGP75166/PKI166, CGP59326A, BIBX1382). The two most advanced EGFR inhibitors in development are C225 and ZD1839. C225 is an antibody directed against the ligand-binding domain of human EGFR, which competes for receptor binding with EGF and other ligands. In vitro, C225 inhibits EGFR tyrosine kinase activity and proliferation of EGFR-overexpressing squamous cell carcinoma cell lines. Synergy was observed with doxorubicin, cisplatin and radiation in preclinical models. In phase I trials, major toxicity has been dermatological (rash and acneic skin reactions); allergic reactions have also been observed in about 3% of cases. This agent, administered intravenously once weekly, is presently in phase III trials in HNSCC and colon cancer. ZD1839, a synthetic molecule which targets the EGFR ATP binding site, is a very specific inhibitor of EGFR tyrosine kinase activity. Synergy has been observed with paclitaxel and cisplatin. In phase I trials, responses were seen in advanced NSCLC, and cutaneous toxicity and diarrhea were the most important side effects. Oral chronic daily administration is feasible. Two large randomized trials have been completed in advanced NSCLC in combination with chemotherapy. A large phase II study in second and third line has demonstrated a single agent activity of 18.5%. Another large phase II study in patients who received prior platinum and docetaxel obtained a response rate of 11%. There was no difference in response rate between the 250 and the 500 mg/day doses, but side effects were higher in patients who received the 500 mg dose. A very similar small molecule, OSI-774, has also shown activity in this setting. Two large randomized phase III studies of ZD1839 have recently been completed and analyzed in which two doses of ZD1839 (250 or 500 mg/day) or placebo were given in combination with two different chemotherapy regimens (carboplatin-paclitaxel or carboplatin-gemcitabine). These studies failed to demonstrate an increase in survival by adding ZD1839 together with chemotherapy in patients with advanced NSCLC.
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PMID:The epidermal growth factor receptor pathway and its inhibition as anticancer therapy. 1498 46

Several lines of evidence suggest that tumor-derived trypsin contributes to the growth and invasion of cancer cells. We have recently shown that trypsin is a potent growth factor for colon cancer cells through activation of the G protein-coupled receptor protease-activated receptor 2 (PAR2). Here, we analyzed the signaling pathways downstream of PAR2 activation that lead to colon cancer cell proliferation in HT-29 cells. Our data are consistent with the following cascade of events upon activation of PAR2 by the serine protease trypsin or the specific PAR2-activating peptide (AP2): (i) a matrix metalloproteinase-dependent release of transforming growth factor (TGF)-alpha, as demonstrated with TGF-alpha-blocking antibodies and measurement of TGF-alpha in culture medium; (ii) TGF-alpha-mediated activation of epidermal growth factor receptor (EGF-R) and subsequent EGF-R phosphorylation; and (iii) activation of ERK1/2 and subsequent cell proliferation. The links between these events are demonstrated by the fact that stimulation of cell proliferation and ERK1/2 upon activation of PAR2 is reversed by the metalloproteinase inhibitor batimastat, TGF-alpha-neutralizing antibodies, EGF-R ligand binding domain-blocking antibodies, and the EGF-R tyrosine kinase inhibitors AG1478 and PD168393. Therefore, transactivation of EGF-R appears to be a major mechanism whereby activation of PAR2 results in colon cancer cell growth. By using the Src tyrosine kinase inhibitor PP2, we further showed that Src plays a permissive role for PAR2-mediated ERK1/2 activation and cell proliferation, probably acting downstream of the EGF-R. These data explain how trypsin exerts robust trophic action on colon cancer cells and underline the critical role of EGF-R transactivation.
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PMID:Protease-activated receptor 2 in colon cancer: trypsin-induced MAPK phosphorylation and cell proliferation are mediated by epidermal growth factor receptor transactivation. 1501 Apr 75

We have demonstrated that folic acid inhibits cell proliferation and epidermal growth factor receptor (EGFR) activation in colon cancer cell lines. We examined the effect of one year supplemental folic acid (5 mg/day) on the rectal mucosal expression of beta-catenin and pGSK3beta, known to be affected by EGF-R, in patients with colorectal adenomas. Folic acid treatment significantly reduced nuclear expression of beta-catenin (P < 0.05) and cellular expression of pGSK3beta (P < 0.01) when compared to placebo. Folic acid may exert its chemopreventive effect, at least in part, through inhibition of nuclear translocation of beta-catenin.
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PMID:Folic acid reduces nuclear translocation of beta-catenin in rectal mucosal crypts of patients with colorectal adenomas. 1501 56

Studies on chemoprevention of colorectal cancer have generated increasing interest. The mechanisms involved in NSAIDs chemopreventive action are not fully elucidated. In this study, we examined in human colon cancer cells the effect of indomethacin and NS-398 (a pre-clinical selective COX-2 inhibitor) on expression of 96 genes of the EGF/PDGF signaling pathways essential for cell proliferation, migration, and survival. We found that indomethacin and NS-398 treatment significantly upregulated expression of the tumor suppressor gene, PTEN, the MAP kinase phosphatase-3, MKP-3, and the protein tyrosine phosphatase, SHP2. Additionally, NS-398 treatment increased expression of apoptotic genes such as BAD, STAT1, and CASP3. These results suggest that as a consequence of increased expression of phosphatases such as PTEN and the resulting dephosphorylation of kinases, NSAIDs can negatively regulate the EGF/PDGF pathways in colon cancer cells-a novel mechanism for NSAIDs' chemopreventive actions.
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PMID:NSAIDs activate PTEN and other phosphatases in human colon cancer cells: novel mechanism for chemopreventive action of NSAIDs. 1524 Jan 29

Two of the most promising new targets in the treatment of colorectal cancer are the epithelial growth factor receptor (EGFR) and the vascular endothelial growth factor (VEGF). Agents that inhibit the EGFR or bind to VEGF have demonstrated clinical activity as single agents and in combination with chemotherapy in phase II and phase III clinical trials. The most promising of these agents are cetuximab, which blocks the binding of EGF and transforming growth factor alpha (TGF-alpha) to EGFR, and bevacizumab, which binds free VEGF. Cetuximab and irinotecan have been evaluated in two clinical studies in the USA (IMCL CP02-0141 and IMCL CP02-9923). Study IMCL CP02-0141 evaluated the antitumor activity of single-agent cetuximab in patients with irinotecan-refractory, EGFR-positive metastatic colorectal carcinoma. There were 6 partial responses in 57 treated patients, for a response rate of 10.5%. Study IMCL CP02-9923 evaluated the combination of cetuximab and irinotecan in a total of 139 patients enrolled at 27 study sites. In this trial 22.5% of patients with progressive disease on irinotecan achieved an objective response (19% by investigator assessment) showing that the combination of cetuximab and irinotecan has antitumor activity in this population. A large randomized phase II trial evaluating similar study populations in Europe confirmed these findings, demonstrating response rates for cetuximab/irinotecan and cetuximab alone of 22.9% and 10.8%, respectively. The other promising agent bevacizumab is a humanized variant of the anti-VEGF monoclonal antibody. VEGF is produced by healthy and neoplastic cells. Its activities are mediated by two receptor tyrosine kinases. VEGF signaling is often a rate-limiting step in physiologic and pathologic angiogenesis. Bevacizumab has been studied as an antiangiogenic cancer therapeutic as a single agent and in combination with chemotherapy in patients with stage III and IV colon cancer. In addition to its direct antiangiogenic effects, bevacizumab may allow more efficient delivery of chemotherapy by altering tumor vasculature and decreasing the elevated interstitial pressure common in tumors. In this regard, some of the most robust phase II data using bevacizumab are from a randomized study of chemotherapy [fluorouracil (5-FU) and leucovorin (LV)] with or without bevacizumab in metastatic colorectal cancer. In this study, treatment with bevacizumab plus 5-FU/LV resulted in higher response rates, longer median time to disease progression, and longer median survival. Recently, a phase III, multicenter, double-blind, randomized, placebo-controlled trial was designed to investigate the addition of bevacizumab to first-line irinotecan, 5-FU, and LV chemotherapy (IFL). The trial showed a higher response rate, longer time to tumor progression, and prolonged overall survival in patients with metastatic colorectal cancer. It was the first large, randomized, phase III survival trial to assess the importance of targeting VEGF and tumor angiogenesis for the treatment of human cancer. Integration of novel agents targeting VEGF and EGFR with irinotecan-based chemotherapy has shown clinical activity in patients with metastatic colorectal cancer. The goal in the future will be to predict which specific chemotherapy and targeted agent combination will most likely benefit individual patients.
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PMID:Integration of novel agents in the treatment of colorectal cancer. 1530 12

Mortality from colorectal cancer, a leading cause of death in the U.S.A. and other western countries, has remained unchanged over the past 45 years. Therefore, the search for strategies to prevent the development and progression of colorectal cancer has markedly intensified. Chemoprevention is one such strategy. Accumulating evidence suggests that folic acid, a water soluble vitamin, could be an effective chemopreventive agent for colorectal cancer. Results from several studies have demonstrated that a diet deficient in folic acid may be associated with an increased risk of colonic neoplasia, whereas dietary supplementation of this nutrient may be chemopreventive. Although the mechanisms by which folic acid exerts its chemopreventive role in colorectal carcinogenesis remain to be fully elucidated, supplemental folic acid has been shown to arrest the loss of heterozygosity (LOH) of the tumor suppressor gene DCC (deleted in colorectal cancer) and to stabilize its protein in normal appearing rectal mucosa of patients with colorectal adenomas. Data from in vitro studies utilizing colon cancer cell lines suggest that supplemental folic acid or its metabolite 5-methyltetrahydrofolate (5-MTF) attenuates the expression and activation of EGF-receptor (EGFR) as well as proliferation of cells. The folic acid mediated reduction of EGFR function could partly be the result of suppression of EGFR gene through increased methylation of CpG sequences within its promoter.
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PMID:Chemopreventive role of folic acid in colorectal cancer. 1535 9


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