Activated wnt signaling in stroma contributes to development of pancreatic mucinous cystic neoplasms.
OBJECTIVE
Pancreatic mucinous cystic neoplasm (MCN), a cystic tumor of the pancreas that develops most frequently in women, is a potential precursor to pancreatic ductal adenocarcinoma. MCNs develop primarily in the body and tail of the pancreas and are characterized by the presence of a mucinous epithelium and ovarian-like subepithelial stroma. We investigated the involvement of Wnt signaling in KRAS-mediated pancreatic tumorigenesis and development of MCN in mice, and Wnt activation in human MCN samples.


METHODS
LSL-Kras(G12D), Ptf1a-cre mice were crossed with elastase-tva mice to allow for introduction of genes encoded by the replication-competent avian sarcoma-leukosis virus long-terminal repeat with splice acceptor viruses to pancreatic acinar cells and acinar cell progenitors, postnatally and sporadically. Repeat with splice acceptor viruses that expressed Wnt1 were delivered to the pancreatic epithelium of these mice; pancreatic lesions were analyzed by histopathology and immunohistochemical analyses. We analyzed levels of factors in Wnt signaling pathways in 19 MCN samples from patients.


RESULTS
Expression of Wnt1 in the pancreatic acinar cells and acinar cell progenitors of female mice led to development of unilocular or multilocular epithelial cysts in the pancreas body and tail, similar to MCN. The cystic lesions resembled the estrogen receptor- and progesterone receptor-positive ovarian-like stroma of MCN, but lacked the typical mucinous epithelium. Activated Wnt signaling, based on nuclear localization of β-catenin, was detected in the stroma but not cyst epithelium. Wnt signaling to β-catenin was found to be activated in MCN samples from patients, within the ovarian-like stroma, consistent with the findings in mice.


CONCLUSIONS
Based on studies of mice and pancreatic MCN samples from patients, the canonical Wnt signaling pathway becomes activated and promotes development of the ovarian-like stroma to contribute to formation of MCNs.
Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts; Division of Pathology, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, Japan. Electronic address: sano.makoto@nihon-u.ac.jp.
Makoto
M
Sano
Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts.
David R
DR
Driscoll
Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts.
Wilfredo E
WE
De Jesus-Monge
Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York.
David S
DS
Klimstra
Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts; Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts; Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts. Electronic address: Brian.Lewis@umassmed.edu.
Brian C
BC
Lewis
D000818:Animals; D021441:Carcinoma, Pancreatic Ductal / Q000378:metabolism; D002471:Cell Transformation, Neoplastic / Q000378:metabolism; D018282:Cystadenocarcinoma, Mucinous / Q000378:metabolism*; D005260:Female; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D060449:Wnt Signaling Pathway; D051155:Wnt1 Protein / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism*
D051155:Wnt1 Protein; D051176:beta Catenin
ER; FZD; MCN; Mouse Model; Mucinous Cystic Neoplasm (MCN); Ovarian-Like Stroma; PCP; PDAC; PR; PanIN; RCAS; Wnt Signaling Pathway; estrogen receptor; frizzled; mucinous cystic neoplasm; pancreatic ductal adenocarcinoma; pancreatic intraepithelial neoplasia; planar cell polarity; progesterone receptor; replication-competent avian sarcoma-leukosis virus long-terminal repeat with splice acceptor