title: Inactivating mutations of RNF43 confer Wnt dependency in pancreatic ductal adenocarcinoma.
abstract: A growing number of agents targeting ligand-induced Wnt/β-catenin signaling are being developed for cancer therapy. However, clinical development of these molecules is challenging because of the lack of a genetic strategy to identify human tumors dependent on ligand-induced Wnt/β-catenin signaling. Ubiquitin E3 ligase ring finger 43 (RNF43) has been suggested as a negative regulator of Wnt signaling, and mutations of RNF43 have been identified in various tumors, including cystic pancreatic tumors. However, loss of function study of RNF43 in cell culture has not been conducted, and the functional significance of RNF43 mutations in cancer is unknown. Here, we show that RNF43 inhibits Wnt/β-catenin signaling by reducing the membrane level of Frizzled in pancreatic cancer cells, serving as a negative feedback mechanism. Inhibition of endogenous Wnt/β-catenin signaling increased the cell surface level of Frizzled. A panel of 39 pancreatic cancer cell lines was tested for Wnt dependency using LGK974, a selective Porcupine inhibitor being examined in a phase 1 clinical trial. Strikingly, all LGK974-sensitive lines carried inactivating mutations of RNF43. Inhibition of Wnt secretion, depletion of β-catenin, or expression of wild-type RNF43 blocked proliferation of RNF43 mutant but not RNF43-wild-type pancreatic cancer cells. LGK974 inhibited proliferation and induced differentiation of RNF43-mutant pancreatic adenocarcinoma xenograft models. Our data suggest that mutational inactivation of RNF43 in pancreatic adenocarcinoma confers Wnt dependency, and the presence of RNF43 mutations could be used as a predictive biomarker for patient selection supporting the clinical development of Wnt inhibitors in subtypes of cancer.
authors.affiliation: Developmental and Molecular Pathways, Novartis Institutes for Biomedical Research, Cambridge, MA 02139, USA.
authors.forename: Xiaomo
authors.initials: X
authors.lastname: Jiang
authors.forename: Huai-Xiang
authors.initials: HX
authors.lastname: Hao
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Growney
authors.forename: Steve
authors.initials: S
authors.lastname: Woolfenden
authors.forename: Cindy
authors.initials: C
authors.lastname: Bottiglio
authors.forename: Nicholas
authors.initials: N
authors.lastname: Ng
authors.forename: Bo
authors.initials: B
authors.lastname: Lu
authors.forename: Mindy H
authors.initials: MH
authors.lastname: Hsieh
authors.forename: Linda
authors.initials: L
authors.lastname: Bagdasarian
authors.forename: Ronald
authors.initials: R
authors.lastname: Meyer
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Smith
authors.forename: Monika
authors.initials: M
authors.lastname: Avello
authors.forename: Olga
authors.initials: O
authors.lastname: Charlat
authors.forename: Yang
authors.initials: Y
authors.lastname: Xie
authors.forename: Jeffery A
authors.initials: JA
authors.lastname: Porter
authors.forename: Shifeng
authors.initials: S
authors.lastname: Pan
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Margaret E
authors.initials: ME
authors.lastname: McLaughlin
authors.forename: Feng
authors.initials: F
authors.lastname: Cong
mesh_terms: D000217:Acyltransferases; D000970:Antineoplastic Agents / Q000494:pharmacology; D021441:Carcinoma, Pancreatic Ductal / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D017321:Clinical Trials, Phase I as Topic; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051157:Frizzled Receptors / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D060449:Wnt Signaling Pathway; D051176:beta Catenin
chemical_list: D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D051157:Frizzled Receptors; D008565:Membrane Proteins; D015513:Oncogene Proteins; D051153:Wnt Proteins; D051176:beta Catenin; D000217:Acyltransferases; C491188:PORCN protein, human; C496945:RNF43 protein, human; D044767:Ubiquitin-Protein Ligases