title: RNF43 and ZNRF3 are commonly altered in serrated pathway colorectal tumorigenesis.
abstract: Serrated pathway colorectal cancers (CRCs) are characterised by a BRAF mutation and half display microsatellite instability (MSI). The Wnt pathway is commonly upregulated in conventional CRC through APC mutation. By contrast, serrated cancers do not mutate APC. We investigated mutation of the ubiquitin ligases RNF43 and ZNRF3 as alternate mechanism of altering the Wnt signal in serrated colorectal neoplasia. RNF43 was mutated in 47/54(87%) BRAF mutant/MSI and 8/33(24%) BRAF mutant/microsatellite stable cancers compared to only 3/79(4%) BRAF wildtype cancers (p<0.0001). ZNRF3 was mutated in 16/54(30%) BRAF mutant/MSI and 5/33(15%) BRAF mutant/microsatellite stable compared to 0/27 BRAF wild type cancers (p=0.004). An RNF43 frameshift mutation (X659fs) occurred in 80% BRAF mutant/MSI cancers. This high rate was verified in a second series of 25/35(71%) BRAF mutant/MSI cancers. RNF43 and ZNRF3 had lower transcript expression in BRAF mutant compared to BRAF wildtype cancers and less cytoplasmic protein expression in BRAF mutant/MSI compared to other subtypes. Treatment with a porcupine inhibitor reduced RNF43/ZNRF3 mutant colony growth by 50% and synergised with a MEK inhibitor to dramatically reduce growth. This study suggests inactivation of RNF43 and ZNRF3 is important in serrated tumorigenesis and has identified a potential therapeutic strategy for this cancer subtype.
authors.affiliation: Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Bond
authors.affiliation: Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Diane M
authors.initials: DM
authors.lastname: McKeone
authors.affiliation: Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Murugan
authors.initials: M
authors.lastname: Kalimutho
authors.affiliation: Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.|Envoi Specialist Pathologists, Brisbane, Queensland, Australia.|School of Medicine, University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Bettington
authors.affiliation: Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Sally-Ann
authors.initials: SA
authors.lastname: Pearson
authors.affiliation: Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Troy D
authors.initials: TD
authors.lastname: Dumenil
authors.affiliation: Cancer and Population Studies, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Leesa F
authors.initials: LF
authors.lastname: Wockner
authors.affiliation: Department of Oncology, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.
authors.forename: Matthew
authors.initials: M
authors.lastname: Burge
authors.affiliation: Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.|School of Medicine, University of Queensland, Brisbane, Queensland, Australia.|Department of Gastroenterology and Hepatology, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Leggett
authors.affiliation: Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.|School of Medicine, University of Queensland, Brisbane, Queensland, Australia.|Pathology Queensland, Brisbane, Queensland, Australia.
authors.forename: Vicki L J
authors.initials: VL
authors.lastname: Whitehall
mesh_terms: D000368:Aged; D063646:Carcinogenesis / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D008297:Male; D053842:Microsatellite Instability; D009154:Mutation; D015513:Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D044767:Ubiquitin-Protein Ligases / Q000235:genetics* / Q000378:metabolism; D060449:Wnt Signaling Pathway / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D015513:Oncogene Proteins; C496945:RNF43 protein, human; D044767:Ubiquitin-Protein Ligases; C572950:ZNRF3 protein, human; D048493:Proto-Oncogene Proteins B-raf
keywords: BRAF; MSI; RNF43; Wnt signalling; colorectal cancer