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)

Cyclooxygenase-2 (COX-2) is expressed early in colon carcinogenesis and is known to play a crucial role in the progress of the disease. Here we show that the regulation of the expression of this enzyme in a colon cancer cell line, and in patients, is associated with overexpression of the Wnt pathway-associated proteins, Pontin52/TIP49a and LEF-1. Recently shown to be essential for transformation via the c-Myc pathway, Pontin52/TIP49a promotes COX-2 expression in tissue culture and is overexpressed in colon cancer tissue, co-localizing with COX-2 expression in transformed tissue, relative to paired normal tissue.
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PMID:Regulation of COX-2 transcription in a colon cancer cell line by Pontin52/TIP49a. 1467 89

Beta-catenin has a key role in Wnt signaling via effects on T-cell factor (TCF)-mediated transcription. Mutational defects in beta-catenin regulation are seen in many cancers, leading to elevated beta-catenin levels, enhanced binding of beta-catenin to TCFs, and increased expression of TCF-regulated genes. Factors cooperating with beta-catenin in transcription of TCF-regulated genes are not well defined. TIP49, an ATPase previously implicated as a cofactor for oncogenic transformation by c-Myc, has been shown to bind to beta-catenin. We found that expression of an ATPase-deficient mutant form of TIP49 (TIP49D302N) substantially inhibited beta-catenin-mediated neoplastic transformation of immortalized rat epithelial cells and anchorage-independent growth of human colon cancer cells with deregulated beta-catenin. The TIP49D302N mutant inhibited beta-catenin-mediated activation of TCF-dependent cellular genes. Similar inhibition of the expression of beta-catenin/TCF-dependent genes was seen with small interfering RNA approaches against endogenous TIP49. TIP49 was found in complexes with chromatin remodeling and histone-modifying factors and cofactors, including the TIP60 histone acetylase-associated proteins transactivation/transformation-domain associated protein (TRRAP) and BAF53. Using chromatin immunoprecipitation methods, the TIP49, TIP60, and TRRAP proteins were found to interact with sequences in the regulatory region of the gene for ITF-2, a TCF-dependent cellular gene. The ability of TIP49D302N to inhibit ITF-2 gene expression was linked to decreased acetylation of histones in the vicinity of the TCF-binding sites in the ITF-2 promoter region. We suggest that TIP49 is an important cofactor in beta-catenin/TCF gene regulation in normal and neoplastic cells, likely functioning in chromatin remodeling.
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PMID:TIP49 regulates beta-catenin-mediated neoplastic transformation and T-cell factor target gene induction via effects on chromatin remodeling. 1469 87

Inappropriate transcriptional repression involving histone deacetylases (HDACs) is a prominent cause for the development of leukemia. We now identify faulty expression of a specific mediator of transcriptional repression in a solid tumor. Loss of the adenomatosis polyposis coli (APC) tumor suppressor induces HDAC2 expression depending on the Wnt pathway and c-Myc. Increased HDAC2 expression is found in the majority of human colon cancer explants, as well as in intestinal mucosa and polyps of APC-deficient mice. HDAC2 is required for, and sufficient on its own to prevent, apoptosis of colonic cancer cells. Interference with HDAC2 by valproic acid largely diminishes adenoma formation in APC(min) mice. These findings point toward HDAC2 as a particularly relevant potential target in cancer therapy.
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PMID:Induction of HDAC2 expression upon loss of APC in colorectal tumorigenesis. 1514 53

The routine multidisciplinary management of colon cancer is based mainly on tumor staging, histology, grading and vascular invasion. In this approach, important individual information derived from molecular characteristics of the tumor may be missed, especially since significant heterogeneity of molecular aberrations in cancer cells has been observed, and recognition of every of relationships between them may be of value. K-RAS, C-MYC and C-ERBB2 are protooncogenes taking part in carcinogenesis and tumor progression in the colon. They influence cell proliferation, differentiation and survival. K-RAS point mutation, as well as amplification of C-MYC and C-ERBB2 were searched in 84 primary colon adenocarcinomas resected with curative intent. Multiplex polymerase-chain reaction and restriction fragment length polymorphism were performed to assess codon 12 K-RAS point mutation. Amplification of C-MYC and C-ERBB2 genes was evaluated by densitometry after agarose gel separation of the respective multiplex PCR products. No relation was found among mutated and/or amplified genes, and between searched molecular aberrations and pathoclinical features. In multivariate analysis, nodal status appeared to be the only independent prognostic indicator. In colon adenocarcinoma, codon 12 K-RAS point mutation and amplification of C-MYC and C-ERBB2 seem to occur independently in the process of tumor progression. Amplification of C-ERBB2 tends to associate with more advanced stage of disease. Concomitant occurrence of codon 12 K-RAS mutation, C-MYC and C-ERBB2 amplification was of no prognostic value in respect to survival.
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PMID:K-RAS point mutation, and amplification of C-MYC and C-ERBB2 in colon adenocarcinoma. 1549 79

Suppression of apoptosis is thought to contribute to carcinogenesis. Survivin, a member of the inhibitor-of-apoptosis family, blocks apoptotic signaling activated by various cellular stresses. Since elevated expression of survivin observed in human cancers of varied origin was associated with poor patient survival, survivin has attracted growing attention as a potential target for cancer treatment. Immortalization of cells also is required for carcinogenesis; telomere length maintenance by telomerase is required for cancer cells to proliferate indefinitely. Yet how cancer cells activate telomerase remains unclear. We therefore examined possible interrelationships between survivin expression and telomerase activity. Correlation between survivin and human telomerase reverse transcriptase (hTERT) expression was observed in colon cancer tissues, and overexpression of survivin enhanced telomerase activity by up-regulation of hTERT expression in LS180 human colon cancer cells. DNA-binding activities of specificity protein 1 (Sp1) and c-Myc to the hTERT core promoter were increased in survivin gene transfectant cells. Phosphorylation of Sp1 and c-Myc at serine and threonine residues was enhanced by survivin, while total amounts of these proteins were unchanged. Further, "knockdown" of survivin by a small inhibitory RNA decreased Sp1 and c-Myc phosphorylation. Thus survivin participates not only in inhibition of apoptosis, but also in prolonging cellular lifespan.
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PMID:Survivin enhances telomerase activity via up-regulation of specificity protein 1- and c-Myc-mediated human telomerase reverse transcriptase gene transcription. 1581 55

The integrin beta4 subunit has been shown to be involved in various aspects of cancer progression. The aim of the present work was to evaluate the expression of beta4 in primary colon cancers and to investigate the occurrence of a previously identified intestinal nonfunctional variant of beta4 (beta4ctd-) for adhesion to laminin. Immunodetection of beta4 using a panel of antibodies and RT-PCR analyses were performed on series of paired primary colon tumors and corresponding resection margins. The beta4 subunit was found to be significantly overexpressed in cancer specimens at both the protein and transcript levels. Surprisingly, beta4 levels of expression were closely correlated with those of the oncogene c-Myc in individual specimens. In vitro studies of c-Myc overexpression showed an upregulation of beta4 promoter activity. Finally, the beta4ctd- form was identified in the normal proliferative colonic cells but was found to be predominantly absent in colon cancer cells, both in situ and in vitro. We concluded that the beta4ctd- form is lost from colon cancer cells, while the level of the wild-type form of beta4, which is functional for adhesion to laminin, is increased in primary tumors in relation with the expression of c-Myc.
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PMID:Upregulation of a functional form of the beta4 integrin subunit in colorectal cancers correlates with c-Myc expression. 1600 43

The present study was designed to investigate the effects of two main constituents of green tea, (-)-epigallocatechin-3-gallate (EGCG) and caffeine, on intestinal tumorigenesis in Apc(min/+) mice, a recognized mouse model for human intestinal cancer, and to elucidate possible mechanisms involved in the inhibitory action of the active constituent. We found that p.o. administration of EGCG at doses of 0.08% or 0.16% in drinking fluid significantly decreased small intestinal tumor formation by 37% or 47%, respectively, whereas caffeine at a dose of 0.044% in drinking fluid had no inhibitory activity against intestinal tumorigenesis. In another experiment, small intestinal tumorigenesis was inhibited in a dose-dependent manner by p.o. administration of EGCG in a dose range of 0.02% to 0.32%. P.o. administration of EGCG resulted in increased levels of E-cadherin and decreased levels of nuclear beta-catenin, c-Myc, phospho-Akt, and phospho-extracellular signal-regulated kinase 1/2 (ERK1/2) in small intestinal tumors. Treatment of HT29 human colon cancer cells with EGCG (12.5 or 20 micromol/L at different times) also increased protein levels of E-cadherin by 27% to 58%, induced the translocation of beta-catenin from nucleus to cytoplasm and plasma membrane, and decreased c-Myc and cyclin D1 (20 micromol/L EGCG for 24 hours). These results indicate that EGCG effectively inhibited intestinal tumorigenesis in Apc(min/+) mice, possibly through the attenuation of the carcinogenic events, which include aberrant nuclear beta-catenin and activated Akt and ERK signaling.
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PMID:Inhibition of intestinal tumorigenesis in Apcmin/+ mice by (-)-epigallocatechin-3-gallate, the major catechin in green tea. 1628 56

The c-myc oncogene encodes for a transcriptional factor involved in many cellular processes such as proliferation, differentiation and apoptosis. According to these different functions, the role of c-Myc protein in cellular sensitivity to anti-cancer drugs is controversial. We defined the role of c-Myc in cancer cell sensitivity to vinblastine (VLB) using human colon cancer cells: LoVo wild-type or transfected with a plasmid containing the human c-myc gene in antisense orientation (LoVo-mycANS). Analysis of VLB cytotoxicity demonstrated a 3-fold increase in VLB sensitivity in LoVo-mycANS cells. Comparison between cells revealed different apoptosis kinetics: accumulation of cells in sub-G1 phase and poly(ADP-ribose) polymerase cleavage occurred earlier in LoVo-mycANS. Then, we demonstrated a mitochondrial membrane potential disruption followed by cytochrome c release that indicates the involvement of mitochondria in this apoptotic signaling pathway. This earlier apoptosis was accompanied by a Bcl-2 decrease and a p53 increase. In conclusion, the decrease in c-Myc expression enhanced the VLB sensitivity, triggering earlier apoptosis through induction of the intrinsic pathway. Thus, c-myc induction is a resistance factor and our findings suggest that tumors carrying low levels of c-Myc protein could be more responsive to vinca alkaloids treatment. Moreover, the downregulation of c-myc oncogene by an antisense strategy might represent a useful goal for improving the efficacy of this anti-neoplastic drug family.
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PMID:Decrease in c-Myc activity enhances cancer cell sensitivity to vinblastine. 1642 36

Elevated expression of c-myc has been detected in a broad range of human cancers, indicating a key role for this oncogene in tumor development. Recently, an interaction between FUSE-binding protein-interacting repressor (FIR) and TFIIH/p89/XPB helicase was found to repress c-myc transcription and might be important for suppressing tumor formation. In this study, we showed that enforced expression of FIR induced apoptosis. Deletion of the NH(2)-terminal repression domain of FIR rescued the cells from apoptosis as did coexpression of c-Myc with FIR; thus, repression of Myc mediates FIR-driven apoptosis. Surprisingly, a splicing variant of FIR unable to repress c-myc or to drive apoptosis was frequently discovered in human primary colorectal cancers but not in the adjacent normal tissues. Coexpression of this splicing variant with repressor-competent FIR, either in HeLa cells or in the colon cancer cell line SW480, not only abrogated c-Myc suppression but also inhibited apoptosis. These results strongly suggest the expression of this splicing variant promotes tumor development by disabling FIR repression and sustaining high levels of c-Myc and opposing apoptosis in colorectal cancer.
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PMID:An essential role of alternative splicing of c-myc suppressor FUSE-binding protein-interacting repressor in carcinogenesis. 1645 96

alpha-Tocopherol succinate (TS), an analogue of vitamin E, has growth-inhibitory activity in a wide spectrum of in vitro and in vivo cancer models. Here, we report that modulation of oncogenic Ras is associated with TS activity. TS inhibits the proliferation and induces apoptosis of NIH3T3 cells stably transfected with oncogenic K-Ras and H-Ras, but not NIH3T3 cells expressing empty vector. TS treatment resulted in decreased Ras protein levels in oncogenic Ras expressing NIH3T3 cells but not in parental NIH3T3 cells. Treatment with TS suppressed the levels of phospho-Akt and phospho-Erk1/2 in oncogenic Ras expressing NIH3T3 cells. Overexpression of constitutively active phosphoinositide-3-kinase, Akt, and Mek1/2 significantly attenuated TS growth inhibition of oncogenic Ras-transformed NIH3T3 mouse fibroblast cell lines. In addition, transcriptional targets of oncogenic Ras such as c-Myc, cyclin D1, and E2F1 were down-regulated by TS in oncogenic Ras-expressing cells. The above TS effects on oncogenic Ras signaling were also observed in endogenous oncogenic K-Ras expressing HCT 116 (human colon cancer) and MDA-MB-231 (human breast cancer) cells. Taken together, these data show that TS down-regulation of the Ras signaling pathways that are mediated by Mek/Erk and phosphoinositide-3-kinase/Akt plays, at least in part, a critical role in TS inhibition of proliferation and survival of transformed cells. This data supports further investigation of the chemopreventive and therapeutic potential of TS in tumors that are dependent on activated Ras signaling and identifies phosphor-Erk and phosphor-Akt as potential biomarkers of TS activity.
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PMID:RRR-alpha-tocopherol succinate down-regulates oncogenic Ras signaling. 1650 4


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