A GNAS mutation found in pancreatic intraductal papillary mucinous neoplasms induces drastic alterations of gene expression profiles with upregulation of mucin genes.
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.
Institute for Integrated Medical Sciences, Tokyo Women's Medical University, Tokyo, Japan ; Department of Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Hirotake
H
Komatsu
Institute for Integrated Medical Sciences, Tokyo Women's Medical University, Tokyo, Japan.
Etsuko
E
Tanji
Department of Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Naoaki
N
Sakata
Department of Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Takeshi
T
Aoki
Department of Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Fuyuhiko
F
Motoi
Department of Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Takeshi
T
Naitoh
Department of Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan ; Division of Integrated Surgery and Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Yu
Y
Katayose
Department of Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Shinichi
S
Egawa
Department of Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Michiaki
M
Unno
Institute for Integrated Medical Sciences, Tokyo Women's Medical University, Tokyo, Japan.
Toru
T
Furukawa
D002288:Adenocarcinoma, Mucinous / Q000235:genetics* / Q000473:pathology; D017209:Apoptosis; D014408:Biomarkers, Tumor / Q000235:genetics*; D015153:Blotting, Western; D021441:Carcinoma, Pancreatic Ductal / Q000235:genetics* / Q000473:pathology; D002291:Carcinoma, Papillary / Q000235:genetics* / Q000473:pathology; D002453:Cell Cycle; D049109:Cell Proliferation; D002864:Chromogranins; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000235:genetics*; D020869:Gene Expression Profiling; D006801:Humans; D009077:Mucins / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D014408:Biomarkers, Tumor; D002864:Chromogranins; D009077:Mucins; D012333:RNA, Messenger; C406732:GNAS protein, human; D019205:GTP-Binding Protein alpha Subunits, Gs