title: Bisphosphonates inhibit expression of p63 by oral keratinocytes.
abstract: Osteonecrosis of the jaw (ONJ), a side-effect of bisphosphonate therapy, is characterized by exposed bone that fails to heal within eight weeks. Healing time of oral epithelial wounds is decreased in the presence of amino-bisphosphonates; however, the mechanism remains unknown. We examined human tissue from individuals with ONJ and non-bisphosphonate-treated control individuals to identify changes in oral epithelium and connective tissue. Oral and intravenous bisphosphonate-treated ONJ sites had reduced numbers of basal epithelial progenitor cells, as demonstrated by a 13.8±1.1% and 31.9±5.8% reduction of p63 expression, respectively. No significant differences in proliferation rates, vessel density, or macrophage number were noted. In vitro treatment of clonal and primary oral keratinocytes with zoledronic acid (ZA) inhibited p63, and expression was rescued by the addition of mevalonate pathway intermediates. In addition, both ZA treatment and p63 shRNA knock-down impaired formation of 3D Ex Vivo Produced Oral Mucosa Equivalents (EVPOME) and closure of an in vitro scratch assay. Analysis of our data suggests that bisphosphonate treatment may delay oral epithelial healing by interfering with p63-positive progenitor cells in the basal layer of the oral epithelium in a mevalonate-pathway-dependent manner. This delay in healing may increase the likelihood of osteonecrosis developing in already-compromised bone.
authors.affiliation: Department of Periodontics and Oral Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
authors.forename: E L
authors.initials: EL
authors.lastname: Scheller
authors.forename: C M
authors.initials: CM
authors.lastname: Baldwin
authors.forename: S
authors.initials: S
authors.lastname: Kuo
authors.forename: N J
authors.initials: NJ
authors.lastname: D'Silva
authors.forename: S E
authors.initials: SE
authors.lastname: Feinberg
authors.forename: P H
authors.initials: PH
authors.lastname: Krebsbach
authors.forename: P C
authors.initials: PC
authors.lastname: Edwards
mesh_terms: D053687:Adult Stem Cells / Q000187:drug effects*; D000704:Analysis of Variance; D050071:Bone Density Conservation Agents / Q000009:adverse effects*; D016022:Case-Control Studies; D002461:Cell Line, Transformed; D004164:Diphosphonates / Q000009:adverse effects*; D015870:Gene Expression / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D007093:Imidazoles / Q000009:adverse effects*; D007571:Jaw Diseases / Q000139:chemically induced / Q000235:genetics*; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D008798:Mevalonic Acid / Q000378:metabolism; D010020:Osteonecrosis / Q000139:chemically induced / Q000235:genetics*; D034741:RNA, Small Interfering; D046509:Tissue Culture Techniques; D014945:Wound Healing / Q000187:drug effects / Q000235:genetics; D000077211:Zoledronic Acid
chemical_list: D050071:Bone Density Conservation Agents; C081876:CKAP4 protein, human; D004164:Diphosphonates; D007093:Imidazoles; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D000077211:Zoledronic Acid; D008798:Mevalonic Acid