Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0699790 (colon cancer)
 28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chronic inflammation predisposes to cancer. Transforming growth factor (TGF)-beta, a multifunctional protein, suppresses the growth of normal colonic epithelial cells, whereas it stimulates the proliferation of cancer cells. Interleukin (IL)-10-deficient mice, which develop colitis and colorectal cancer, show an increased level of plasma TGF-beta. Although TGF-beta may be a key molecule in the development of colon cancer arising from chronic colitis in IL-10-deficient mice, the role of TGF-beta still remains unclear. TGF-beta activates not only TGF-beta type I receptor (TbetaRI) but also c-Jun N-terminal kinase (JNK), which converts the mediator Smad3 into two distinctive phosphoisoforms: C-terminally phosphorylated Smad3 (pSmad3C) and linker-phosphorylated Smad3 (pSmad3L). We studied C57BL/6-IL-10-deficient mice (n=18) at 4 to 32 weeks of age. We investigated histology, and pSmad2/3L, pSmad2/3C, and p53 by immunohistochemistry. pSmad3L staining was detected in the cancer cells in all 10 mice with colonic cancer and in the epithelial cells in 7 of 12 mice with colonic dysplasia, but not in the normal or colitic mice. pSmad3c was detected without any significant difference between stages. p53 was weakly stained in a few cancer cells in 5 out of 10 mice. Smad3L signaling plays an important role in the carcinogenesis of chronic colitis in IL-10-deficient mice.
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PMID:Involvement of Smad3 phosphoisoform-mediated signaling in the development of colonic cancer in IL-10-deficient mice. 1849 83

Although Smad signalling is known to play a tumour suppressor role, it has been shown to play a prometastatic function also in breast cancer and melanoma metastasis to bone. In contrast, mutation or reduced level of Smad4 in colorectal cancer is directly correlated to poor survival and increased metastasis. However, the functional role of Smad signalling in metastasis of colorectal cancer has not been elucidated. We previously reported that overexpression of Smad7 in colon adenocarcinoma (FET) cells induces tumorigenicity by blocking TGF-beta-induced growth inhibition and apoptosis. Here, we have observed that abrogation of Smad signalling by Smad7 induces liver metastasis in a splenic injection model. Polymerase chain reaction with genomic DNA from liver metastases indicates that cells expressing Smad7 migrated to the liver. Increased expression of TGF-beta type II receptor in liver metastases is associated with phosphorylation and nuclear accumulation of Smad2. Immunohistochemical analyses have suggested poorly differentiated spindle cell morphology and higher cell proliferation in Smad7-induced liver metastases. Interestingly, we have observed increased expression and junctional staining of Claudin-1, Claudin-4 and E-cadherin in liver metastases. Therefore, this report demonstrates, for the first time, that blockade of TGF-beta/Smad pathway in colon cancer cells induces metastasis, thus supporting an important role of Smad signalling in inhibiting colon cancer metastasis.
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PMID:Smad7 induces hepatic metastasis in colorectal cancer. 1878 Nov 53

Expression of matrix metalloproteinase 7 (MMP7) is increased in the human colorectal carcinomas, and correlates with malignant progression. However, its contribution to colon cancer pathogenesis is not understood thoroughly. To investigate the roles of MMP7 in colon cancer progression, we introduced an Mmp7 knockout mutation into the cis-Apc/Smad4 mutant mouse, a model of invasive colon cancer in which SMAD4-dependent TGF-beta family signaling is inactivated. We demonstrate here that lack of MMP7 reduces the number and size of tumors in the cis-Apc/Smad4 mice. On the other hand, MMP7-deficiency does not affect the depth of tumor invasion, number of stromal fibroblasts or levels of extracellular matrix components in the tumors. These results indicate that MMP7 is required for tumor formation, but not for the invasion or fibrosis of the colon cancer whose SMAD4-dependent TGF-beta family signaling is blocked.
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PMID:Matrix metalloproteinase 7 is required for tumor formation, but dispensable for invasion and fibrosis in SMAD4-deficient intestinal adenocarcinomas. 1900 10

There are a number of kinase inhibitors that regulate components of the neovasculature. We previously reported the use of transforming growth factor (TGF)-beta inhibitor on neovasculature in stroma-rich tumor models to increase the intratumoral distribution of nanoparticles. Here, we compared the effects of two other kinase inhibitors, imatinib and sorafenib, with TGF-beta inhibitor (LY364947) on extravasation of a modeled nanoparticle, 2 MDa dextran. We first used a mouse model of neoangiogenesis, the Matrigel plug assay, to compare neovasculature formed inside of and around Matrigel plugs (intraplug and periplug regions, respectively). Intraplug vasculature was more strongly pericyte covered, whereas periplug vasculature was less covered. In this model, TGF-beta inhibitor exhibited the most potent effect on intraplug vasculature in increasing the extravasation of dextran, whereas sorafenib had the strongest effect on periplug vasculature. Although imatinib and TGF-beta inhibitor each reduced pericyte coverage, imatinib also reduced the density of endothelium, resulting in a decrease in overall delivery of nanoparticles. These findings were confirmed in two tumor models, the CT26 colon cancer model and the BxPC3 pancreatic cancer model. The vasculature phenotype in the CT26 model resembled that in the periplug region, whereas the latter resembled that in the intraplug region. Consistent with this, sorafenib most potently enhanced the accumulation of nanoparticles in the CT26 model, whereas TGF-beta inhibitor did in the BxPC3 model. In conclusion, the appropriate strategy for optimization of tumor vasculature for nanoparticles may differ depending on tumor type, and in particular on the degree of pericyte coverage around the vasculature.
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PMID:Comparison of the effects of the kinase inhibitors imatinib, sorafenib, and transforming growth factor-beta receptor inhibitor on extravasation of nanoparticles from neovasculature. 1903 99

Recent studies have reported that Smad4 has a TGF-beta-independent function as a tumor suppressor in cooperating with beta-catenin/Lef to regulate target gene expression. The objective of this research was to study the role of Smad4 in colon cancer migration and its potential mechanism. In our study, stable colon cancer cells that have increased Smad4 expression were created using a eukaryotic vector containing Smad4-pcDNA3.1(+). Smad4 restoration directly suppressed the Wnt/beta-catenin signal activity in SW480 cells by down-regulating beta-catenin expression and altering its localization from cytoplasm and nucleus to the plasma membrane. Up-regulation of Smad4 also increased the expression of E-cadherin and decreased the transcriptional activity of beta-catenin/Tcf target genes, such as claudin-1 and MMP-7. SW480 cells with increased Smad4 expression had decreased in vitro cell migration. The data suggested that restoration of Smad4 in Smad4-deficient cells may provide a potential therapeutic strategy for intervention of colon cancer migration and metastasis.
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PMID:Smad4 restoration leads to a suppression of Wnt/beta-catenin signaling activity and migration capacity in human colon carcinoma cells. 1928 91

Colon cancer is the third most common cancer and third most common cause of cancer-related death in the USA according to 2008 American Cancer Society statistics. The carcinogenesis of colon cancer has been associated with both genetics and environmental factors. It has been found that several signal pathways, including K-ras, Src/PI3K/Akt, beta-catenin, TGFbeta and p53 play critical roles in its pathogenesis. The 5 y survival rate of metastatic colon cancer is below 10%. Thus, it is necessary to further understand its biology and search for effective therapy. Azoxymethane (AOM) is a common model for colon cancer. It can specifically induce colon cancer similar to the pathogenesis of human sporadic colon cancer. Thus, it has been extensively used in the study of the molecular biology, prevention and treatment of colon cancer. After administration, AOM is metabolised into methylazoxymethanol by CYP2E1, which causes DNA mutations. Mutation of K-ras activates this pathway and its downstream PI3K/Akt pathway and MAPK pathway. Mutation of beta-catenin also prevents it from being degraded by GSK-3 and accumulation of beta-catenin leads to cell proliferation. TGFbeta, a pro-apoptotic protein, is inhibited. All of these changes form the basis of AOM carcinogenesis. This model has been used in the study of the genetic deficiencies of colon cancer and in the prevention and treatment of the disease. For example, TGF-betaR2 and adiponectin knockout mice are more susceptible to AOM, while high amylose cornstarch, green tea and artemisia have protective effects.
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PMID:The signal pathways in azoxymethane-induced colon cancer and preventive implications. 1950 80

Schlafen-3 (Slfn-3), a novel gene, has been shown to be a negative regulator of proliferation. The current investigation was undertaken to determine whether Slfn-3 might play a role in regulating cellular differentiation. Butyric acid, a short chain fatty acid, which induced differentiation of intestinal cells as evidenced by increased alkaline phosphatase (ALP) activity in the rat small intestinal IEC-6 cells, also produced a marked increase in Slfn-3 expression. Furthermore, overexpression of Slfn-3 caused stimulation of ALP activity in IEC-6 cells, which was exacerbated by butyrate. On the other hand, downregulation of Slfn-3 by slfn-3-si-RNA greatly attenuated the butyrate-mediated induction of differentiation of IEC-6 cells. Additionally, we observed that increased expression of Slfn-3 in colon cancer HCT-116 cells stimulated TGF-beta expression and modulated expression of its downstream effectors as evidenced by increased expression of p27kip1 and downregulation of CDK-2. In addition, Slfn-3 increases E-cadherin expression but downregulates beta-catenin. In conclusion, our data show that Slfn-3 plays a critical role in regulating intestinal mucosal differentiation. Furthermore our data also show that TGF-beta signaling pathway plays an important role in mediating slfn-3 induced differentiation.
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PMID:Schlafen-3: a novel regulator of intestinal differentiation. 1970 12

Functional expression of KAL1 gene is critical in the migration of GnRH neurons from the olfactory placode to the hypothalamus in embryogenesis. This gene thus far has not been shown to play a functional role in any other physiological or pathological process either in the developed brain or in peripheral tissues. We show here that KAL1 gene expression is decreased in early stage and increased in later stages of cancers. Screening of colon, lung and ovarian cancer cDNA panels indicated significant decrease in KAL1 expression in comparison to corresponding uninvolved tissues. However, KAL1 expression increased with the progression of cancer from early (I and II) stages to later (III and IV) stages of the cancer. There was a direct correlation between the TGFbeta and KAL1 expression in colon cancer cDNA. Using colon cancer cell lines, we showed that TGFbeta induces KAL1 gene expression and secretion of anosmin-1 protein (KAL1 coded protein). We further report that hypoxia induces anosmin-1 expression; anosmin-1 protects cancer cells from apoptosis activated by hypoxia and increases cancer cell mobility. Using siRNA technique we found that KAL1 expression following hypoxia is hypoxia-inducible factor (HIF-1)alpha dependent. Our results suggest that KAL1 gene expression plays an important role in cancer metastasis and protection from apoptosis.
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PMID:Anosmin-1 involved in neuronal cell migration is hypoxia inducible and cancer regulated. 1984 65

Identifying molecular factors of sensitivity and resistance of cancer cells to enzastaurin, a drug inhibiting protein kinase C (PKC) beta, remains a major challenge to improve its clinical development. Investigating the cellular effects of enzastaurin in a panel of 20 human cancer cell lines, we found that most cells displaying oncogenic K-Ras mutations also display resistance to enzastaurin. Wild-type (WT) K-Ras cancer cells displaying high sensitivity to enzastaurin also expressed high mRNA levels of epithelial markers, such as E-cadherin (CDH1), and low mRNA expressions of mesenchymal markers, such as vimentin, N-cadherin (CDH2), and other genes frequently expressed in mesenchymal transition such as ZEB1, TWIST, SLUG, SNAIL, and TGFbeta. WT K-Ras enzastaurin-resistant cells also expressed high levels of mesenchymal markers. Based on this observation, the effects of enzastaurin were investigated in epithelial colon COLO205-S cells that expressed WT Ras/Raf and its derived COLO205-R mesenchymal counterpart selected for resistance to most PKC modulators and displaying oncogenic K-Ras (G13D/exon 2). In COLO205-S cells, inhibition of phosphorylated PKCbeta led to the inactivation of AKT and glycogen synthase kinase 3beta and was associated with apoptosis without significant effect on cell cycle progression. In COLO205-R cells, enzastaurin induced mainly necrosis at high concentrations. In COLO205-R cells, a strong activation of extracellular signal-regulated kinase 1/2 possibly due to oncogenic K-Ras was predominantly associated with transcription of potent antiapoptotic genes, such as BCL2, GADD45B, and CDKN1A, as well as the multidrug resistance gene ABCB1. From this study, colon cancer cells undergoing apoptosis under enzastaurin exposure seem to frequently express a WT Ras and an epithelial phenotype.
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PMID:Epithelial-to-mesenchymal transition and oncogenic Ras expression in resistance to the protein kinase Cbeta inhibitor enzastaurin in colon cancer cells. 2040 51

Significant advances have been made in understanding the biology of colorectal cancer. In this chapter, we review the key signaling pathways that play key roles in maintaining the growth and proliferation of colorectal cancer. The pathways that will be discussed include Wnt/beta-catenin, TGF-beta/SMAD, Notch, Hedgehog, epidermal growth factor receptor, Ras, and PI3K/Akt. In addition, we review the growing role of colon cancer stem cells in mediating cellular drug resistance and cancer recurrence. This enhanced understanding of cancer biology provides important insights for developing novel therapies that target specific growth factor receptors and/or certain critical signal transduction pathways. These targeted therapies can then be used alone or in combination with standard cytotoxic chemotherapy regimens.
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PMID:Biology of colorectal cancer. 2052 96


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