Figure 2
From: Epigenetic silencing of monoallelically methylated miRNA loci in precancerous colorectal lesions
Pri-miR-497/195 CpG island methylation in paired samples of normal colorectal mucosa and adenomas (six exemplary pairs from the 50 patients) and differential expression of miR-195 and miR-497 in the dysplastic mucosa of adenomas with hypermethylated or normally methylated pri-miR-497/195 CpG island. (a) COBRA of colorectal adenomas and corresponding normal mucosa samples. Case 9: a normally methylated sample; the other cases: hypermethylated samples. Arrows indicate TaqαI-digested DNA fragments representing methylated alleles; and slower-migrating fragments represent undigested, unmethylated DNA. The weak residual band corresponding to TaqαI-undigested alleles reflects low-level stromal contamination in these endoscopic biopsy specimens, which is absent in the epithelial cell lines shown in Figure 1c. (b) An example of BGS from a normal/adenoma tissue pair. Each row shows the methylation status of a cloned target sequence. Circles represent unmethylated (white) and methylated (black) CpG dinucleotides. (c) Relative miR-195 and miR-497 expression in colorectal adenomas that were normally methylated (n=5) or hypermethylated (n=5) at the pri-miR-497/195 CpG island. These samples were chosen over 40 other adenomas (7 normally methylated and 33 hypermethylated) because of their high epithelial cell contents reflected by low Vimentin expression (data not shown). **P=0.0025 (miR-195) and P=0.0087 (miR-497) vs expression in the normally methylated tumors.
