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- Dimberg, Jan, et al.
(author)
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Enhanced expression of cyclooxygenase-2 and nuclear beta-catenin are related to mutations in the APC gene in human colorectal cancer
- 2001
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In: Anticancer Research. - 0250-7005 .- 1791-7530. ; 21:2A, s. 911-915
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Journal article (peer-reviewed)abstract
- Mutational inactivation of the human tumour suppressor gene adenomatous polyposis coli (APC) results in constitutive activation of beta -catenin/T cell factor-4 (Tcf-4) mediated transcription of target genes. Up-regulation of cyclooxygenase-2 (COX-2) protein is frequently found in human colorectal cancer (CRC). We analysed 38 CRC for mutations in APC and beta -catenin and found an association between APC mutations and elevated COX-2 levels. Furthermore, APC mutations were predominantly observed in tumour tissues from the rectum compared to tumours of colonic origin. Western blot analysis revealed that nuclear beta -catenin levels were generally higher in tumours with APC mutations compared to tumours with wild type APC. However, there was also a higher level of nuclear beta -catenin in tumour compared to normal tissue, hut nuclear Tcf-4 protein was constitutively expressed in tumour and normal tissue and showed no differences. An identified putative Tcf-4 binding element in the COX-2 promoter may partly explain the enhanced level of COX-2 and support the idea that COX-2 may be a downstream target of the APC/beta -catenin/Tcf-4 pathway.
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- Elander, Nils, et al.
(author)
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Association Between Adenomatosis Polyposis Coli Functional Status and Microsomal Prostaglandin E Synthase-1 Expression in Colorectal Cancer
- 2009
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In: Molecular Carcinogenesis. - : Wiley. - 0899-1987 .- 1098-2744. ; 48:5, s. 401-407
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Journal article (peer-reviewed)abstract
- Bioactive metabolites downstream of cyclooxygenase-2 (COX-2) generated prostaglandin H-2 (PGH(2)), in particular prostaglandin E-2 (PGE(2)), are thought to play critical roles during the development of colorectal tumors. Previous reports reveal that defects of the tumor suppressor adenomatosis polyposis coli (APC) contribute to COX-2 upregulation in colon tumor cells. We investigated whether a similar relation was present between APC functional status and the expression of microsomal prostaglandin E synthase-1 (mPGES-1), which acts downstream of COX-2 and catalyses the terminal conversion of PGH(2) into PGE(2). Surprisingly, mPGES-1 mRNA and protein levels were upregulated upon induction of a wild type-APC carrying vector in HT29 colon cancer cells, and downregulated following siRNA silencing of APC in HCT-116 cells. mPGES-1 was overall enhanced in human colorectal tumor specimens versus corresponding non-tumor mucosa and, in accordance with data on HT29 and HCT116 cells, higher levels of mPGES-1 were observed among tumors carrying wild type versus mutant APC. RNAi silencing of beta-catenin and luciferase assays regarding the mPGES-1 promoter region did not reveal a role for APC or beta-catenin/Tcf in controlling mPGES-1 gene transcription. However, RNA degradation assays in HT29 cells revealed a suppressed degradation of mPGES-1 in the presence of wild type APC, implying that mPGES-1 mRNA is stabilized in the APC wild type state. Collectively, we demonstrate a novel association between APC functional status and mPGFS-1 expression in colorectal tumor cells, being most likely related to reduced mPGES-1 mRNA degradation rate in the APC wild type state.
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- Monstein, Hans-Jürg, et al.
(author)
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K-ras and B-raf gene mutations are not associated with gastrin- and CCK2-receptor mRNA expression in human colorectal tumour tissues
- 2004
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In: European Journal of Clinical Investigation. - : Wiley. - 0014-2972 .- 1365-2362. ; 34:2, s. 100-106
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Journal article (peer-reviewed)abstract
- Background: Colorectal cancer is a multistep process caused by genetic alterations in cell growth regulatory genes such as K-ras and B-raf. It has been assumed that mutations in the K-ras gene induce gastrin gene expression and that gastrin stimulates the growth of colorectal cancer in an autocrine fashion by coexpressing gastrin and cholecystokinin (CCK)2 receptors. The aim of this study was to examine a possible association of K-ras and B-raf gene mutations with gastrin and CCK2 receptor mRNA expression in human colon and rectum tumour biopsy specimens. Methods: K-ras and B-raf gene mutations as well as gastrin and CCK2 receptor mRNA expression in 50 colon and 46 rectum biopsies, respectively, were determined using molecular biology methods. Results: K-ras mutations occurred in 44% colon and 30% rectum and B-raf mutations in 16% colon and 4% rectum tumours, respectively. Gastrin mRNA was expressed in 64% colon and 61% rectum tumours, whereas CCK2 receptor mRNAs was expressed in 32% colon and 13% rectum tumours. K-ras or B-raf gene mutations and simultaneous gastrin mRNA expression was observed in 40% colon and 17% rectum tumours, respectively. Coexpression of gastrin and CCK2 receptor mRNA occurred in 20% colon and 9% rectal tumours. Conclusions: The results do not support the hypothesis that K-ras and B-raf gene mutations have an impact on gastrin- and CCK-receptor mRNA expression in colorectal tumour tissues.
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- Ungerbäck, Jonas, et al.
(author)
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Analysis of VEGF polymorphisms, tumor expression of VEGF mRNA and colorectal cancer susceptibility in a Swedish population
- 2009
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In: MOLECULAR MEDICINE REPORTS. - : Spandidos Publications. - 1791-2997. ; 2:3, s. 435-439
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Journal article (peer-reviewed)abstract
- Vascular endothelial growth factor (VEGF) plays a significant role in tumor angiogenesis and is found to be overexpressed and involved in the development and progression of colorectal cancer (CRC). The VEGF gene contains several polymorphic sites known to influence VEGF expression. We examined the possible association between five polymorphisms, located in the promoter/5-untranslated region [-2578 (C/A), -2549 (del/ins 18 bp) -1154 (G/A), -634 (G/C)] or 3-untranslated region [+936 (C/T)] of the VEGF gene, and CRC Susceptibility and clinicopathological characteristics in 302 Swedish CRC patients and 336 healthy randomly selected controls. Both genotypes and combined haplotypes were analyzed. No significant differences were observed when VEGF genotype/haplotype frequencies in the CRC cases and controls were compared, nor were any associations found between the genotypes/haplotypes and clinicopathological characteristics. However, when the -2578 C and +936 T alleles were combined, a small but significant association with CRC susceptibility was detected (OR=1.6, 95% CI 1.3-1.9, p=0.01). In addition, VEGF mRNA expression was determined in a Subset of patients, revealing a 2-fold VEGF upregulation in CRC tissue compared to normal colonic mucosa, but no association between the genotypes or haplotypes and VEGF mRNA levels. Linkage analysis was performed, revealing that the polymorphisms in the promoter and 5-untranslated region were in tight linkage disequilibrium (LD) (vertical bar Dvertical bar=0.91-1.00), while the +936 C/T polymorphism was only weakly associated with the others (vertical bar Dvertical bar=0.05-0.19). In conclusion, VEGF is generally upregulated in colorectal tumors. However, the single nucleotide polymorphisms examined do not appear to influence the mRNA expression of VEGF in colorectal tumors, and most likely play a limited role in CRC development and progression.
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| 10. |
- Österström, Anna, et al.
(author)
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Expression of cytosolic and group X secretory phospholipase A2 genes in human colorectal adenocarcinomas
- 2002
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In: Cancer Letters. - 0304-3835 .- 1872-7980. ; 182:2, s. 175-182
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Journal article (peer-reviewed)abstract
- Gene expression of cytosolic phospholipase A2 (cPLA2) and protein level of secretory PLA2 group X (sPLA2-X) are upregulated in human colorectal cancer and provide cyclooxygenase-2 (COX-2) with arachidonic acid, resulting in increased levels of PGE2. Mutated ras-genes are suggested to be involved in the regulatory pathway of cPLA2 in lung cancer cells. We analysed the gene expression of cPLA2 and sPLA2-X in 42 and 38 primary colorectal tumours, respectively, with and without K-ras mutations. We found an up-regulation of cPLA2 mRNA but the induction in tumour tissues does not correlate with Ras-gene mutations. Moreover, our results cannot consistently reflect an overexpression of sPLA2-X gene in colorectal cancer tissues.
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