title: GATA6 activates Wnt signaling in pancreatic cancer by negatively regulating the Wnt antagonist Dickkopf-1.
abstract: Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease characterized by late diagnosis and treatment resistance. Recurrent genetic alterations in defined genes in association with perturbations of developmental cell signaling pathways have been associated with PDAC development and progression. Here, we show that GATA6 contributes to pancreatic carcinogenesis during the temporal progression of pancreatic intraepithelial neoplasia by virtue of Wnt pathway activation. GATA6 is recurrently amplified by both quantitative-PCR and fluorescent in-situ hybridization in human pancreatic intraepithelial neoplasia and in PDAC tissues, and GATA6 copy number is significantly correlated with overall patient survival. Forced overexpression of GATA6 in cancer cell lines enhanced cell proliferation and colony formation in soft agar in vitro and growth in vivo, as well as increased Wnt signaling. By contrast siRNA mediated knockdown of GATA6 led to corresponding decreases in these same parameters. The effects of GATA6 were found to be due to its ability to bind DNA, as forced overexpression of a DNA-binding mutant of GATA6 had no effects on cell growth in vitro or in vivo, nor did they affect Wnt signaling levels in these same cells. A microarray analysis revealed the Wnt antagonist Dickopf-1 (DKK1) as a dysregulated gene in association with GATA6 knockdown, and direct binding of GATA6 to the DKK1 promoter was confirmed by chromatin immunoprecipitation and electrophoretic mobility shift assays. Transient transfection of GATA6, but not mutant GATA6, into cancer cell lines led to decreased DKK1 mRNA expression and secretion of DKK1 protein into culture media. Forced overexpression of DKK1 antagonized the effects of GATA6 on Wnt signaling in pancreatic cancer cells. These findings illustrate that one mechanism by which GATA6 promotes pancreatic carcinogenesis is by virtue of its activation of canonical Wnt signaling via regulation of DKK1.
authors.affiliation: Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhong
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Baojin
authors.initials: B
authors.lastname: Fu
authors.forename: Fan
authors.initials: F
authors.lastname: Pan
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yachida
authors.forename: Mousumi
authors.initials: M
authors.lastname: Dhara
authors.forename: Emilia
authors.initials: E
authors.lastname: Albesiano
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Naito
authors.forename: Felip
authors.initials: F
authors.lastname: Vilardell
authors.forename: Christopher
authors.initials: C
authors.lastname: Cummings
authors.forename: Paola
authors.initials: P
authors.lastname: Martinelli
authors.forename: Ang
authors.initials: A
authors.lastname: Li
authors.forename: Raluca
authors.initials: R
authors.lastname: Yonescu
authors.forename: Qingyong
authors.initials: Q
authors.lastname: Ma
authors.forename: Constance A
authors.initials: CA
authors.lastname: Griffin
authors.forename: Francisco X
authors.initials: FX
authors.lastname: Real
authors.forename: Christine A
authors.initials: CA
authors.lastname: Iacobuzio-Donahue
mesh_terms: D002278:Carcinoma in Situ / Q000235:genetics / Q000473:pathology; D021441:Carcinoma, Pancreatic Ductal / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D018450:Disease Progression; D050993:GATA6 Transcription Factor / Q000378:metabolism*; D018628:Gene Dosage / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000473:pathology; D015398:Signal Transduction; D051153:Wnt Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*
chemical_list: C501126:DKK1 protein, human; D050993:GATA6 Transcription Factor; C494759:GATA6 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D051153:Wnt Proteins