E-cadherin belongs to the cadherin family of calcium-dependent cell-adhesion molecules. The cadherins play an essential role in biological processes such as ordering of cell sorting, migration, and differentiation, and their malfunctioning is connected with neoplasia. Neoplastic progression in patients with chronic ulcerative colitis is characterized by the development of epithelial dysplasia. Transcriptional silencing of tumor-suppressor genes by promoter methylation has been observed in different types of human cancers and dysplasia. To explore the mode of E-cadherin regulation, 156 biopsy samples from 26 patients with long-standing ulcerative colitis were screened. To detect the methylation status of our samples, a methylation-specific PCR was applied. Methylation of the E-cadherin (CDH1) promoter was detected in 93% of the patients with dysplastic biopsy samples, in contrast to only 6% of the patients without dysplasia (P < 0.001). We also examined the level of synthesis of E-cadherin protein by immunohistochemical staining in different paraffin-embedded samples of dysplastic and non-dysplastic origin in a subset of our patients. Samples with dysplasia displayed reduced levels, whereas samples without dysplasia revealed normal E-cadherin protein synthesis. These results show that the E-cadherin promoter is subjected to epigenetic control in colorectal ulceration. Obviously, this event may play an important role in the progression from chronic inflammation to colorectal cancer. For this reason, methylation of the CDH1 promoter is an attractive new biomarker for detecting ulcerative colitis patients with a high risk for developing colorectal cancers.
Trefoil factor family (TFF) peptides promote cell migration, heal the mucosa and may suppress tumor growth. In reporter gene assays we show that aspirin (1^12 mM) evokes a six-fold up-regulation of TFF2, but not TFF1 and TFF3 transcription in human gastrointestinal cell lines. 6 h after application up-regulation of endogenous TFF2 mRNA was observed. TFF2 transcription was enhanced by indomethacin and arachidonic acid but repressed by staurosporine, suggesting mediation via protein kinase C. We mapped an aspirin responding element 3 3546 to 3 3758 bp upstream of TFF2. Upregulation of TFF2 by aspirin may partially explain the chemopreventive potential of low dose aspirin in gastrointestinal carcinogenesis. ß 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.
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