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

We have previously shown that an autocrine factor (CRDGF) of molecular weight 25,000 is produced by the HT29 human colon cancer cell line. Although CRDGF was shown to inhibit the binding of epidermal growth factor (EGF) to its receptor, several lines of evidence suggested that it was distinct from EGF or transforming growth factor-alpha (TGF-alpha). In order to check the possibility that CRDGF represents a new member of the EGF family, a four-step purification protocol involving acid gel filtration, cation-exchange high-performance liquid chromatography (HPLC), C18 reversed-phase HPLC and gel permeation HPLC was used to purify this protein to homogeneity. The purified material exhibited a 22 kDa molecular mass on SDS-PAGE. Partial N-terminal amino acid sequence of CRDGF showed identity to amphiregulin (AR), an EGF-related protein. Western blotting experiments using AR-specific antiserum confirmed that CRDGF and AR are identical proteins. In addition, we showed that AR, like EGF or TGF-alpha stimulated the phosphorylation of the epidermal growth factor receptor (EGF-R) on tyrosine residues. This indicates that the AR intracellular signalling pathway involves the activation of EGF-R kinase.
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PMID:Colorectum cell-derived growth factor (CRDGF) is homologous to amphiregulin, a member of the epidermal growth factor family. 133 77

Autocrine stimulation of the epidermal growth factor receptor (EGF-R), by coexpression of transforming growth factor-alpha (TGF-alpha), causes malignant transformation of some fibroblast cell lines. TGF-alpha and EGF-R are both known to be expressed in colon carcinoma tissue and have been shown coexpressed in colon carcinoma cell lines. TGF-alpha autocrine activation of EGF-R has been suggested as a potential mechanism contributing to abnormal growth control in colon cancer. We now report coexpression of TGF-alpha and EGF-R transcripts in morphologically normal colonic epithelium from five individuals, in colonic adenomas from three individuals, and in a nontumorigenic colon adenoma cell line, VACO-330. Functional studies demonstrate VACO-330 growth is stimulated by exogenous TGF-alpha and is completely abolished by a blocking anti-EGF-R antibody. Autocrine stimulation of EGF-R by TGF-alpha is therefore required for growth of the adenoma cell line. Autocrine stimulation of EGF-R by TGF-alpha does not cause malignant transformation of the colonic epithelial cell. In normal and adenomatous human colon TGF-alpha, via either an autocrine or paracrine mechanism, is likely an important physiologic stimulant of epithelial proliferation.
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PMID:Growth stimulation by coexpression of transforming growth factor-alpha and epidermal growth factor-receptor in normal and adenomatous human colon epithelium. 236 25

Two morphologically distinct cell lines, GP2d and GP5d, derived from the same adenocarcinoma of the colon, have been established and characterised. Both clones have the same genetic changes, consistent with the usual pattern of tumour progression in colon cancer. The cells also have an inverted duplication of bands 10q11 to 10q21, but Southern blot analysis failed to identify any translocations involving the ret protooncogene, which maps to this region. GP2d grew by spreading from the edges of microcolonies to form a confluent layer of cells. GP5d grew in discrete islands of cells forming multi-layered colonies. These differing patterns of growth correlated with variation in expression or cellular distribution of alpha 2-integrin, desmoplakin and e-cadherin. Only GP2d responded to exogenously added epidermal growth factor (EGF), transforming growth factor-alpha (TGF alpha) or insulin with an increase in cell numbers, even though both cell lines possessed similar numbers of EGF receptors. Analysis of EGF receptor ligand expression showed that GP5d cells expressed relatively more TGF alpha mRNA than did GP2d; in contrast, amphiregulin mRNA, which was abundant in GP2d, was virtually undetectable in GP5d. Even though GP5d failed to exhibit a growth response to EGF, it underwent a marked epithelial-mesenchymal transition when treated with EGF, indicating separation of growth and morphological responses to EGF.
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PMID:Two newly established cell lines derived from the same colonic adenocarcinoma exhibit differences in EGF-receptor ligand and adhesion molecule expression. 760 66

To investigate whether the urinary excretion of epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) is increased in patients with cancer of the digestive tract, EGF and TGF-alpha were determined in 109 cancer patients and 40 healthy controls. Excluding EGF in hepatocellular carcinoma (HCC) and TGF-alpha in pancreatic cancer, both growth factors in each cancer group were significantly higher than in the control group. A receiver operating characteristic curve and likelihood ratio were applied to obtain the best diagnostic efficiency. Both EGF and TGF-alpha had high specificity (100%) in all cancer group. The high sensitivity of EGF in gastric cancer (100%) and metastatic liver cancer (93.3%), moderate sensitivity of TGF-alpha in metastatic liver cancer (86.6%), colon cancer (80.0%), and HCC (61.7%) suggested that they might be helpful in identifying these cancers. In conclusion, urinary excretion of EGF and TGF-alpha increased in most cancers of the digestive tract. They may be used as tumor markers.
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PMID:Urinary epidermal growth factor receptor-binding growth factors in patients with cancers of the digestive tract. 769 94

Colorectal carcinomas generally show a poor sensitivity to conventional chemotherapeutics. Therefore, novel therapeutic approaches are required to improve the prognosis of colon cancer patients in advanced stage. Several growth factors are involved in the control of colon carcinoma cell proliferation. In particular, the epidermal growth factor (EGF)-related peptides transforming growth factor-alpha (TGF-alpha), amphi-regulin (AR), and CRIPTO (CR) are frequently overexpressed in human colon carcinomas. It has also been recently demonstrated that they can function as autocrine growth factors in human colon carcinoma cells. In fact, antisense (AS) retroviral expression vectors or AS oligonucleotides directed against TGF-alpha, AR, or CR are able to inhibit growth and transformation of several human colon carcinoma cell lines. These data suggest that the EGF-like growth factors and their receptors offer potential as targets for experimental therapy of human colon carcinoma. This article reviews the most recent findings in this field.
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PMID:Epidermal growth factor-related peptides as targets for experimental therapy of human colon carcinoma. 946 51

Colonic mucosal wounds are repaired, in part, by epithelial migration. Signaling mechanisms regulating this migration are poorly characterized. This study aimed to examine the role that the epidermal growth factor (EGF) receptor (EGF-R) and its ligands, EGF and transforming growth factor-alpha (TGF-alpha), play in migration in wounded in vitro models of colonic epithelium. Migration was assessed over 24 h in circular wounds made in confluent monolayers of LIM1215 human colon cancer cells. EGF and TGF-alpha stimulated migration twofold from 4 h after wounding. Basal migration and the motogenic effects of short chain fatty acids and hepatocyte growth factor were mediated through enhanced binding of TGF-alpha to EGF-R, while trefoil peptide-mediated motogenesis required EGF-R activation independently of TGF-alpha binding. Activation of protein kinase C (PKC) stimulated migration, an effect more potent than, and independent of, EGF-R activation. However, neither inhibition of PKC by Ro 31-8220 nor depletion of PKC by pretreatement with phorbol myristate acetate attenuated EGF-R-mediated motogenesis. In conclusion, EGF-R activation via TGF-alpha binding, or intracellularly, mediates basal LIM1215 migration and the effects of several motogens, with the exception of PKC activators. Since EGF-R and PKC have physiological activators in vivo, they may control colonic mucosal repair processes following injury.
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PMID:Role of epidermal growth factor receptor in basal and stimulated colonic epithelial cell migration in vitro. 1038 32

Although accumulating evidence suggests a chemopreventive role for folic acid in colon cancer, the regulation of this process in unknown. We hypothesize that supplemental folic acid exerts its chemopreventive role by inhibiting mucosal hyperproliferation, an event considered to be central to the initiation of carcinogenesis in the gastrointestinal tract. The present investigation examines the effect of supplemental folic acid on proliferation of Caco-2 and HCT-116 colon cancer cell lines. Furthermore, because certain tyrosine kinases, particularly epidermal growth factor receptor (EGFR), play a role in regulating cell proliferation, we also examined the folic acid-induced changes in tyrosine kinase activity and expression of EGFR. In Caco-2 and HCT-116 cells, maintained in RPMI 1640 medium containing 1 microg/ml folic acid, we observed that the supplemental folic acid inhibited proliferation in a dose-dependent manner. Pretreatment of HCT-116 and Caco-2 cell lines with supplemental folic acid (1.25 microg/ml) completely abrogated transforming growth factor-alpha (TGF-alpha)-induced proliferation in both cell lines. Tyrosine kinase activity and the relative concentration of EGFR were markedly diminished in both cell lines following a 24-h exposure to supplemental folic acid. The folic acid-induced inhibition of EGFR tyrosine kinase activity in colon cancer cell lines was also associated with a concomitant reduction in the relative concentration of the 14-kDa membrane-bound precursor form of TGF-alpha. In conclusion, our data suggest that supplemental folic acid is effective in reducing proliferation in two unrelated colon cancer cell lines and that EGFR tyrosine kinase appears to be involved in regulating this process.
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PMID:Folic acid inhibition of EGFR-mediated proliferation in human colon cancer cell lines. 1060 Jul 65

We determined whether hyperplastic mucosa adjacent to colon cancer contributes to neoplastic angiogenesis. Surgical specimens of human colon cancer (40 Dukes' stage B and 34 Dukes' stage C) were analyzed by immunohistochemistry for expression of proliferative and angiogenic molecules. The mucosa adjacent to Dukes' stage C tumors (but not Dukes' stage B tumors) had a higher Ki-67 labeling index and a higher expression of epidermal growth factor receptor and transforming growth factor-alpha than distant mucosa. The expression levels of vascular endothelial growth factor, basic fibroblast growth factor, interleukin-8, and the vascular density in the adjacent mucosa were similar to those in the tumor lesions and significantly higher than those in the distant mucosa. The expression of interferon-beta inversely correlated with the level of pro-angiogenic molecules and the vascular density. The injection of metastatic human colon cancer cells and murine colon cancer cells into the cecal wall of mice induced hyperplastic changes in the adjacent mucosa which expressed higher levels of epidermal growth factor receptor, basic fibroblast growth factor, and vascular endothelial growth factor, and lower levels of interferon-beta than did the control mucosa, which directly correlated with the degree of hyperplasia. These data suggest that metastatic human colon cancer cells can induce hyperplasia in the adjacent mucosa, which in turn produces angiogenic molecules that contribute to neoplastic angiogenesis.
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PMID:Induction of angiogenesis by hyperplastic colonic mucosa adjacent to colon cancer. 1107 12

Epidermal growth factor (EGF) receptor ligands such as EGF and transforming growth factor-alpha (TGF-alpha) play an important role in controlling the proliferation, survival, morphology, and motility of colonic epithelial cells. There is also increasing evidence that growth factors and extracellular matrix (ECM) proteins cooperate to regulate these cellular processes. We have reported previously that autocrine TGF-alpha and an unidentified ECM protein in the serum-free conditioned medium of the human colon carcinoma cell line LIM1215 synergize to induce spreading of these cells in low-density cultures. We have now purified the ECM protein secreted by LIM1215 cells and show that it synergizes with EGF to induce spreading of LIM1215 cells and other human cell lines from the colon and other tissues. The purified ECM migrated as a single protein band with an apparent molecular mass of approximately 800 kDa on SDS-PAGE under nonreducing conditions and, under reducing conditions, as three protein bands of approximately 360, 210, and 200 kDa. Immunoblotting experiments and mass spectrometry analysis of tryptic digests on the purified protein identified the 360-, 210-, and 200-kDa protein bands as laminin alpha5, beta1, and gamma1 chains, respectively, indicating that LIM1215 cells secrete laminin-10 (alpha5 beta1 gamma1). In serum-free medium, LIM1215 cells adhere to laminin-10 primarily via alpha2 beta1 and alpha3 beta1 integrin receptors. EGF-induced spreading of LIM1215 cells on laminin-10 is partially inhibited by pretreatment of the cells with blocking antibodies directed against integrin alpha3 or beta1 but not alpha2, alpha6, or beta4 subunits. Spreading is almost completely inhibited by blocking alpha3 + alpha2, alpha3 + alpha6, or beta1 + beta4 integrin chains and results in cell death. Increased spreading in the presence of EGF correlates with up-regulation of alpha6 beta4 integrins in these cells after exposure to EGF. These results indicate that colon cancer cells attach and spread on laminin-10 via multiple integrin receptors and suggest a critical role for alpha3 beta1 integrins in the spreading response. Together, our results support the concept that the adhesive properties of colon cancer cells are modulated by autocrine production of TGF-alpha and laminin-10 and autocrine induction of appropriate integrins.
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PMID:Colon cancer cells adhesion and spreading on autocrine laminin-10 is mediated by multiple integrin receptors and modulated by EGF receptor stimulation. 1111 42

Epidermal growth factor (EGF) receptors are expressed at high levels in about one third of epithelial cancers, and autocrine activation of EGF receptors appears to be critical for the growth of many tumors. We hypothesized that blockade of the binding sites for EGF and transforming growth factor-alpha on EGF receptors with an antireceptor monoclonal antibody (mAb) might be an effective anti-cancer therapy. We produced murine mAb 225 against EGF receptors and demonstrated blockade of receptor function, as well as inhibition of cell growth in cultures and in nude mouse xenografts. mAb C225 is the human:murine chimeric version of mAb 225. Cell cycle inhibition occurred in G(1) phase, and was due to upregulation of p27(Kip1), resulting in inhibition of cyclin E/cyclin dependent kinase-2 activity and hypophosphorylation of Rb. In addition, the amount and/or activities of a number of proapoptotic molecules were enhanced. The antitumor activity in vivo against xenografts was at least partly attributable to reduced vascularization, resulting from decreased vascular endothelial growth factor and basic fibroblast growth factor production by the tumor cells. Metastasis of xenografts was curtailed with mAB C225 treatment, accompanied by a decrease in tumor production of MMP-9. Further studies showed that mAbs 225 and C225 enhanced the cytotoxicity of chemotherapy against xenografts of a variety of human cancer cell lines. Well established xenografts resistant to either mAb or drug treatment alone were eradicated by the combination therapy. Drugs for which this has been demonstrated include doxorubicin, paclitaxel, cisplatin, and topotecan. Antibody treatment also potentiated the responsiveness of human tumor xenografts to radiation therapy. These findings led to clinical trials of human:murine chimeric mAb C225 in combination with chemotherapy or radiotherapy. Results from phase I and II trials involving more than 500 patients are quite promising, in particular in advanced head and neck cancer treated with C225 plus cisplatin or radiation, in advanced colon cancer treated with C225 plus CPT-11, and in advanced pancreatic cancer treated with C225 plus gemcitabine. Phase III trials are now underway.
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PMID:The epidermal growth factor receptor as a target for cancer therapy. 1135 Jul 23


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