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

Abstract

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 (425% 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 Po0.001). Overexpression was observed in tumors with and without mucinous differentiation. There were inverse associations between expression of all four mucins and p53 overexpression. CDX2 expression was inversely associated with MUC2, MUC5AC and MUC6 expression. Our results suggest that, in methylator-positive tumors, mucin genes on chromosome 11p15.5 region undergo increased expression via mechanisms other than direct regulation by CDX2.

Aberrant expression of annexin A10 is closely related to gastric phenotype in serrated pathway to colorectal carcinoma

“…As ANXA10 is not expressed in the normal colon mucosa, 7,14 the upregulation of ANXA10 indicates that the right and left segments of the large intestine have unique tumorigenetic backgrounds. Consistent with previous observations, 18 we observed that the expression of MUC5AC and MUC6 apomucins was strongly associated with molecular features of the serrated neoplastic pathway, such as BRAF mutation, the CpG island methylator phenotype and microsatellite instability. Moreover, we noted an association between these molecular alterations and ANXA10 positivity.…”

“…Subsequent studies have confirmed the simultaneous activation of gastric mucins in serrated neoplasms and associated invasive carcinomas. [16][17][18] Aberrant gastric metaplasia was evident based on an inverse association The results indicated that ANXA10 was the most important partition factor. First split was created by the presence of ANXA10 expression and successfully separated the majority of subgroups 3 and 4 colorectal carcinomas from subgroups 1 and 2.…”

“…24 In one study, colonic adenomas from various anatomic locations of the colon exhibited distinct DNA methylation clusters. 25 Studies have shown that the de novo regulation of gastric-type mucin (MUC5AC and MUC6) is predominantly observed in proximally located colorectal cancers, 18 and higher MUC6 expression was observed in right-sided serrated polyps than leftsided based on the extent and staining intensity. 16,17 We observed that, in addition to MUC5AC and MUC6, ANXA10 immunoreactivity was highly associated with the right sidedness of the large intestine.…”

“…14,15 The upregulation of ANXA10 in sessile serrated adenoma may indicate an aberrant gastric phenotype in colonic serrated neoplasia; as evidenced by the high expression of gastric foveolar (MUC5AC) and pyloric mucin (MUC6) in sessile serrated adenoma. 16,17 Colorectal cancers exhibiting molecular features related to serrated neoplasia pathways are closely associated with MUC5AC and MUC6 expression, 18 implying that gastric programming participates in the carcinogenesis of a subset of colorectal cancers. This study explored the immunohistochemical expression of ANXA10 in a wide variety of colorectal carcinomas to determine the role of its expression in colorectal cancer.…”

Microsatellite unstable gastrointestinal neuroendocrine carcinomas: a new clinicopathologic entity

“…All cases were thoroughly investigated for the following histological features: neuroendocrine cytologic subtype (small and large cell), type of the exocrine component (adenomas, adenocarcinomas, squamous cell carcinomas), vascular and perineural invasion, presence of necrosis, mitotic count per ten HPF, level of gut wall invasion or infiltration of peripancreatic tissues, and presence of metastases in local lymph nodes. Intra and peritumoral lymphoid infiltration was evaluated using H&E stained sections and CD3 immunostaining and following the criteria proposed by Walsh et al (2013): peritumoral lymphocytes infiltration was defined as a mantle or cap of lymphoid cells at the deepest point of direct spread. We also counted the number of lymphocytes in three different areas at !40 magnification at this level.…”