title: Wnt inhibitory factor 1 (WIF1) is a marker of osteoblastic differentiation stage and is not silenced by DNA methylation in osteosarcoma.
abstract: Wnt pathway targeting is of high clinical interest for treating bone loss disorders such as osteoporosis. These therapies inhibit the action of negative regulators of osteoblastic Wnt signaling. The report that Wnt inhibitory factor 1 (WIF1) was epigenetically silenced via promoter DNA methylation in osteosarcoma (OS) raised potential concerns for such treatment approaches. Here we confirm that Wif1 expression is frequently reduced in OS. However, we demonstrate that silencing is not driven by DNA methylation. Treatment of mouse and human OS cells showed that Wif1 expression was robustly induced by HDAC inhibition but not by methylation inhibition. Consistent with HDAC dependent silencing, the Wif1 locus in OS was characterized by low acetylation levels and a bivalent H3K4/H3K27-trimethylation state. Wif1 expression marked late stages of normal osteoblast maturation and stratified OS tumors based on differentiation stage across species. Culture of OS cells under differentiation inductive conditions increased expression of Wif1. Together these results demonstrate that Wif1 is not targeted for silencing by DNA methylation in OS. Instead, the reduced expression of Wif1 in OS cells is in context with their stage in differentiation.
authors.affiliation: Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Australia. Electronic address: ebaker@svi.edu.au.
authors.forename: Emma K
authors.initials: EK
authors.lastname: Baker
authors.affiliation: Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Australia.
authors.forename: Scott
authors.initials: S
authors.lastname: Taylor
authors.affiliation: Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Australia.
authors.forename: Ankita
authors.initials: A
authors.lastname: Gupte
authors.affiliation: Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Australia.
authors.forename: Alistair M
authors.initials: AM
authors.lastname: Chalk
authors.affiliation: Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Australia.
authors.forename: Shreya
authors.initials: S
authors.lastname: Bhattacharya
authors.affiliation: Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Australia.
authors.forename: Alanna C
authors.initials: AC
authors.lastname: Green
authors.affiliation: Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Australia; Bone Cell Biology and Disease Unit, St. Vincent's Institute of Medical Research, Fitzroy, Australia.
authors.forename: T John
authors.initials: TJ
authors.lastname: Martin
authors.affiliation: Cancer Epigenetics, Garvan Institute of Medical Research, Darlinghurst, Australia.
authors.forename: Dario
authors.initials: D
authors.lastname: Strbenac
authors.affiliation: Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland; SIB Swiss Institute of Bioinformatics, University of Zurich, Zurich, Switzerland.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Robinson
authors.affiliation: Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Australia.
authors.forename: Louise E
authors.initials: LE
authors.lastname: Purton
authors.affiliation: Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Australia. Electronic address: cwalkley@svi.edu.au.
authors.forename: Carl R
authors.initials: CR
authors.lastname: Walkley
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002454:Cell Differentiation; D019175:DNA Methylation; D015536:Down-Regulation; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D010006:Osteoblasts / Q000378:metabolism*; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D016326:Extracellular Matrix Proteins; D036341:Intercellular Signaling Peptides and Proteins; C118544:Wif1 protein, mouse
keywords: HDAC; Methylation; Osteoblast; Osteoporosis; Osteosarcoma; WIF1