title: Smad4 loss synergizes with TGFα overexpression in promoting pancreatic metaplasia, PanIN development, and fibrosis.
abstract: OBJECTIVE
  While overexpression of TGFα has been reported in human pancreatic ductal adenocarcinoma (PDAC), mice with overexpressed TGFα develop premalignant pancreatic acinar-to-ductal metaplasia (ADM) but not PDAC. TGF-β signaling pathway is pivotal to the development of PDAC and tissue fibrosis. Here we sought to investigate the interplay between TGFα and TGF-β signaling in pancreatic tumorigenesis and fibrosis, namely via Smad4 inactivation.
  
  
  METHODS
  The MT-TGFα mouse was crossed with a new Smad4 conditional knock-out mouse (Smad4flox/flox;p48-Cre or S4) to generate Smad4flox/flox;MT-TGFα;p48-Cre (STP). After TGFα overexpression was induced with zinc sulfate water for eight months, the pancreata of the STP, MT-TGFα, and S4 mice were examined for tumor development and fibrotic responses. PanIN lesions and number of ducts were counted, and proliferation was measured by Ki67 immunohistochemistry (IHC). Qualitative analysis of fibrosis was analyzed by Trichrome Masson and Sirius Red staining, while vimentin was used for quantification. Expression analyses of fibrosis, pancreatitis, or desmoplasia associated markers (α-SMA, Shh, COX-2, Muc6, Col1a1, and Ctgf) were performed by IHC and/or qRT-PCR.
  
  
  RESULTS
  Our STP mice exhibited advanced ADM, increased fibrosis, increased numbers of PanIN lesions, overexpression of chronic pancreatitis-related marker Muc6, and elevated expression of desmoplasia-associated marker Col1A1, compared to the MT-TGFα mice. The inactivation of Smad4 in the exocrine compartment was responsible for both the enhanced PanIN formation and fibrosis in the pancreas. The phenotype of the STP mice represents a transient state from ADMs to PanINs, closely mimicking the interface area seen in human chronic pancreatitis associated with PDAC.
  
  
  CONCLUSIONS
  We have documented a novel mouse model, the STP mice, which displayed histologic presentations reminiscent to those of human chronic pancreatitis with signs of early tumorigenesis. The STP mice could be a suitable animal model for interrogating the transition of chronic pancreatitis to pancreatic cancer.
authors: The Department of Pathology, Columbia University Medical Center, New York, New York, United States of America; Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, New York, United States of America.
authors: Dario
authors: D
authors: Garcia-Carracedo
authors: The Department of Pathology, Columbia University Medical Center, New York, New York, United States of America; Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, New York, United States of America.
authors: Chih-Chieh
authors: CC
authors: Yu
authors: Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, New York, United States of America.
authors: Nathan
authors: N
authors: Akhavan
authors: Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, New York, United States of America.
authors: Stuart A
authors: SA
authors: Fine
authors: The Department of Vascular Surgery in the Hospital of the University of Munich, Grosshadern, Germany.
authors: Frank
authors: F
authors: Schönleben
authors: Department of Surgical Oncology and Regulation of Organ Function, Miyazaki University School of Medicine, Miyazaki, Japan.
authors: Naoki
authors: N
authors: Maehara
authors: Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, New York, United States of America.
authors: Dillon C
authors: DC
authors: Karg
authors: The Department of Pathology, Columbia University Medical Center, New York, New York, United States of America; Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, New York, United States of America.
authors: Chuangao
authors: C
authors: Xie
authors: The Department of Pathology, Columbia University Medical Center, New York, New York, United States of America; Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, New York, United States of America.
authors: Wanglong
authors: W
authors: Qiu
authors: Department of Medicine, Columbia University Medical Center, New York, New York, United States of America; Pancreas Center, Columbia University Medical Center, New York, New York, United States of America.
authors: Robert L
authors: RL
authors: Fine
authors: The Department of Pathology, Columbia University Medical Center, New York, New York, United States of America; Department of Surgical Oncology and Regulation of Organ Function, Miyazaki University School of Medicine, Miyazaki, Japan.
authors: Helen E
authors: HE
authors: Remotti
authors: The Department of Pathology, Columbia University Medical Center, New York, New York, United States of America; Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, New York, United States of America; Pancreas Center, Columbia University Medical Center, New York, New York, United States of America; Department of Otolaryngology and Head and Neck Surgery, Columbia University Medical Center, New York, New York, United States of America.
authors: Gloria H
authors: GH
authors: Su
mesh_terms: D061354:Acinar Cells / Q000473:pathology; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D063646:Carcinogenesis / Q000235:genetics; D018450:Disease Progression; D004847:Epithelial Cells / Q000473:pathology; D005355:Fibrosis; D015870:Gene Expression; D055786:Gene Knockout Techniques; D006801:Humans; D008679:Metaplasia / Q000235:genetics / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D010179:Pancreas / Q000473:pathology*; D010182:Pancreatic Diseases / Q000235:genetics* / Q000473:pathology*; D010183:Pancreatic Ducts / Q000473:pathology; D010195:Pancreatitis / Q000378:metabolism; D015398:Signal Transduction; D051901:Smad4 Protein / Q000172:deficiency* / Q000235:genetics* / Q000378:metabolism; D016211:Transforming Growth Factor alpha / Q000235:genetics*
chemical_list: D015415:Biomarkers; D051901:Smad4 Protein; D016211:Transforming Growth Factor alpha