Hyperplastic polyps and sessile serrated 'adenomas' of the colon and rectum display gastric pyloric differentiation

“The original publication is available at www.springerlink.com.”ArticleHistochemistry and Cell Biology. 128(5): 445-455 (2007)journal articl

Expression of MUC2, MUC5AC, MUC5B, and MUC6 mucins in colorectal cancers and their association with the CpG island methylator phenotype

Mucinous differentiation is associated with both CpG island methylator phenotype and microsatellite instability in colorectal cancer. The mucinous phenotype derives from abundant expression of the colonic goblet cell mucin, MUC2, and de novo expression of gastric foveolar mucin, MUC5AC. We, therefore, investigated the protein expression levels of MUC2 and MUC5AC, as well as MUC5B and MUC6, in molecular subtypes of colorectal cancer. Seven-hundred and twenty-two incident colorectal carcinomas occurring in 702 participants of the Melbourne Collaborative Cohort Study were characterized for methylator status, MLH1 methylation, somatic BRAF and KRAS mutations, microsatellite-instability status, MLH1, MSH2, MSH6, and PMS2 mismatch repair, and p53 protein expression, and their histopathology was reviewed. Protein expression levels of MUC2, MUC5AC, MUC5B, MUC6, and the putative mucin regulator CDX2 were compared with molecular and clinicopathological features of colorectal cancers using odds ratios and corresponding 95% confidence intervals. MUC2 overexpression (>25% positive tumor cells) was observed in 33% colorectal cancers, MUC5B expression in 53%, and de novo MUC5AC and MUC6 expression in 50% and 39%, respectively. Co-expression of two or more of the mucins was commonly observed. Expression of MUC2, MUC5AC and MUC6 was strongly associated with features associated with tumorigenesis via the serrated neoplasia pathway, including methylator positivity, somatic BRAF p.V600E mutation, and mismatch repair deficiency, as well as proximal location, poor differentiation, lymphocytic response, and increased T stage (all

Over-expression of cathepsin E and trefoil factor 1 in sessile serrated adenomas of the colorectum identified by gene expression analysis

Sessile serrated adenomas are now recognised as precursor lesions of a substantial subset of colorectal cancers arising via a so-called “serrated pathway”. However, their biological markers remain to be defined. The aim of our study was to identify differentially expressed genes in sessile serrated adenomas and conventional adenomas. Gene expression analysis demonstrated molecular differences between polyp types. Further studies using quantitative real-time polymerase chain reaction on cathepsin E (CTSE) demonstrated a significantly (p < 0.05) higher expression in sessile serrated adenomas as compared to hyperplastic polyp and tubular adenomas. Trefoil Factor 1 showed the same trend of expression for sessile serrated adenomas as compared to hyperplastic polyps and was significantly higher in both polyps compared to tubular adenomas. Immunohistochemistry for both proteins demonstrated strong cytoplasmic staining of abnormal crypts in all sessile serrated adenomas, while staining in tubular adenomas and hyperplastic polyps was absent or weak and focal. BRAF and KRAS mutation analysis were employed to further validate polyp discrimination. The findings demonstrated the positive association of the BRAF mutation, V600E, with sessile serrated adenomas and KRAS mutations with tubular adenomas (p < 0.05). This study demonstrates the over-expression in CTSE, in particular, and TFF1 in sessile serrated adenomas compared to both hyperplastic polyps and tubular adenomas.Maria Caruso, James Moore, Gregory J. Goodall, Michelle Thomas, Stuart Phillis, Anna Tyskin, Glenice Cheetham, Nancy Lerda, Hiroyuki Takahashi and Andrew Ruszkiewic