Preferential Expression of MUC6 in Oncocytic and Pancreatobiliary Types of Intraductal Papillary Neoplasms Highlights a Pyloropancreatic Pathway, Distinct From the Intestinal Pathway, in Pancreatic Carcinogenesis

Departments of Pathology, New York University, NY, USA.
The American journal of surgical pathology (Impact Factor: 5.15). 03/2010; 34(3):364-70. DOI: 10.1097/PAS.0b013e3181cf8bb6
Source: PubMed


The expression of different MUC glycoproteins has helped define cellular lineage in variety of pancreatic neoplasms, and has helped identify distinct carcinogenic pathways such as the intestinal pathway characterized by diffuse/strong MUC2/CDX2 expression in intestinal-type intraductal papillary mucinous neoplasms (IPMNs) and their associated colloid carcinomas (CCs). In this study, the expression profile of MUC6, a pyloric-type mucin, was investigated in both preinvasive and invasive pancreatic neoplasia. Florid papillary ("in-situ") components of 9 intraductal oncocytic papillary neoplasms (IOPNs), 24 IPMNs, and 7 mucinous cystic neoplasms (MCNs), were analyzed immunohistochemically for MUC6 expression, as were 15 PanINs, 112 usual invasive ductal adenocarcinomas (DAs), and 14 CCs. In PanINs, MUC6 expression was limited to the very early areas of PanIN-1A that typically have pyloric features. Expression was lost in later stages. Similarly, in IOPNs or IPMNs or MCNs, MUC6 expression was detectable in the cystic or flat areas that have pyloric-like histology. However, in the more advanced (papillary) components of these neoplasms, MUC6 expression was mostly limited to the "cuboidal-cell" but was not seen in the "columnar-cell" phenotype: there was diffuse or strong expression in 8/9 IOPN and, relatively weaker but consistent expression in all 6/6 pancreatobiliary-type IPMNs; whereas virtually no expression in villous or intestinal-type IPMNs. The 7/8 gastric or foveolar-type IPMNs were also negative; in the single case with positivity, the labeling was limited to high-grade dysplastic areas. Interestingly, the papillae in MCNs were also mostly negative. Among invasive carcinomas, 39/112 DAs and only 1/14 CC expressed MUC6. In DA, the expression did not correlate with survival (P=0.94), or any of the markers of aggressiveness: more than 2-cm tumor size (P=0.76), positive surgical margins (P=0.27), lymph node metastasis (P=0.82), or high grade (P=0.08). In conclusion: (1) The expression of MUC6 in oncocytic and pancreatobiliary-type neoplasms but not in villous or intestinal-type neoplasms supports the presence of a pyloropancreatic pathway distinct from the MUC2/CDX2 expressing intestinal pathway in intraductal papillary neoplasia. (2) MUC6 expression is present in the earliest (nonpapillary) form of any type of preinvasive neoplasia regardless of whether it is PanIN or IOPN or IPMN or MCN suggesting that these entities may share some characteristics early on, but evolve along divergent pathways as they progress.

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Available from: Giuseppe Zamboni, Jan 07, 2014
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    • "Among the transfected cells studied, PK-8 cells exhibited the most consistent upregulation of mucin genes, including MUC2, MUC5B, MUC6, MUC15, and MUC20. Among these genes, MUC2, MUC5B, and MUC6 encode secreted mucins and are known to be expressed abundantly in IPMNs [31], [32]. MUC1, which is commonly expressed in PDACs but relatively rarely in IPMNs [33], [34], was upregulated in PCI-35 and MIA PaCa-2 cells but was downregulated in the PK-8 cells. "
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    ABSTRACT: GNAS, a gene encoding G protein stimulating α subunit, is frequently mutated in intraductal papillary mucinous neoplasms (IPMNs), which are indolent and slow-growing pancreatic tumors that secrete abundant mucin. The GNAS mutation is not observed in conventional ductal adenocarcinomas of the pancreas. To determine the functional significance of the GNAS mutation in pancreatic ductal lineage cells, we examined in vitro phenotypes of cells of pancreatic ductal lineage, HPDE, PK-8, PCI-35, and MIA PaCa-2, with exogenous expression of either wild-type or mutated (R201H) GNAS. We found that exogenous GNAS upregulated intracellular cyclic adenine monophosphate (cAMP), particularly in mutated GNAS transfectants, and upregulated expression of MUC2 and MUC5AC in HPDE and PK-8 cells. By contrast, exogenous GNAS inhibited expression of mucin genes in PCI-35 and MIA PaCa-2 cells, despite upregulation of cAMP. We examined global gene expression profiles of some of the cells transfected with exogenous mutated GNAS (PK-8, PCI-35, and MIA PaCa-2), and found that PK-8 cells exhibited drastic alterations of the gene expression profile, which contrasted with modest alterations in PCI-35 and MIA PaCa-2 cells. To identify a cause of these different effects of exogenous mutated GNAS on phenotypes of the cells, we examined effects of interactions of the signaling pathways of G protein-coupled receptor (GPCR), mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinase (PI3K) on expression of mucin genes. The MAPK and PI3K pathways significantly influenced the expression of mucin genes. Exogenous GNAS did not promote cell growth but suppressed it in some of the cells. In conclusion, mutated GNAS found in IPMNs may extensively alter gene expression profiles, including expression of mucin genes, through the interaction with MAPK and PI3K pathways in pancreatic ductal cells; these changes may determine the characteristic phenotype of IPMN. PK-8 cells expressing exogenous mutated GNAS may be an ideal in vitro model of IPMN.
    Full-text · Article · Feb 2014 · PLoS ONE
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    • "However, we cannot rule out that carbonic anhydrase IX, which can also been seen in normal stomach, liver and gallbladder may simply represent a differentiation towards the pyloropancreatic pathway of intraductal papillary neoplasms. Basturk and colleagues claimed that the tubular/tubulopapillary pathway of ITPN forms a subgroup within the pyloropancreatic pathway [24]. "
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    • "In addition, we confirmed the expression of CLDN18.2, but not CLDN18.1, in all of the pancreatic cancer cell lines examined using RT-PCR. These results agree with those described in several recent articles, which demonstrated an association between the gastric phenotype and early pancreatic ductal lesions (Prasad et al. 2005; Kim et al. 2002; Basturk et al. 2010). The staining results in the IPMNs were intriguing, especially in terms of the relationship between the gastric and intestinal IPMN subtypes. "
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