title: Disruption of a nuclear NFATc2 protein stabilization loop confers breast and pancreatic cancer growth suppression by zoledronic acid.
abstract: The aminobisphosphonate zoledronic acid has elicited significant attention due to its remarkable anti-tumoral activity, although its detailed mechanism of action remains unclear. Here, we demonstrate the existence of a nuclear GSK-3β-NFATc2 stabilization pathway that promotes breast and pancreatic cancer growth in vitro and in vivo and serves as a bona fide target of zoledronic acid. Specifically, the serine/threonine kinase GSK-3β stabilizes nuclear NFATc2 through phosphorylation of the serine-rich SP2 domain, thus protecting the transcription factor from E3-ubiquitin ligase HDM2-mediated proteolysis. Zoledronic acid disrupts this NFATc2 stabilization pathway through two mechanisms, namely GSK-3β inhibition and induction of HDM2 activity. Upon nuclear accumulation, HDM2 targets unphosphorylated NFATc2 for ubiquitination at acceptor lysine residues Lys-684/Lys-897 and hence labels the factor for subsequent proteasomal degradation. Conversely, mutagenesis-induced constitutive serine phosphorylation (Ser-215, Ser-219, and Ser-223) of the SP2 domain prevents NFATc2 from HDM2-mediated ubiquitination and degradation and consequently rescues cancer cells from growth suppression by zoledronic acid. In conclusion, this study demonstrates a critical role of the GSK-3β-HDM2 signaling loop in the regulation of NFATc2 protein stability and growth promotion and suggests that double targeting of this pathway is responsible, at least to a significant part, for the potent and reliable anti-tumoral effects of zoledronic acid.
authors.affiliation: Signaling and Transcription Laboratory, Department of Gastroenterology, Philipps-University of Marburg, D-35043 Marburg, Germany.
authors.forename: Shiv K
authors.initials: SK
authors.lastname: Singh
authors.affiliation: Signaling and Transcription Laboratory, Department of Gastroenterology, Philipps-University of Marburg, D-35043 Marburg, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Baumgart
authors.affiliation: Signaling and Transcription Laboratory, Department of Gastroenterology, Philipps-University of Marburg, D-35043 Marburg, Germany.
authors.forename: Garima
authors.initials: G
authors.lastname: Singh
authors.affiliation: Signaling and Transcription Laboratory, Department of Gastroenterology, Philipps-University of Marburg, D-35043 Marburg, Germany.
authors.forename: Alexander O
authors.initials: AO
authors.lastname: König
authors.affiliation: Signaling and Transcription Laboratory, Department of Gastroenterology, Philipps-University of Marburg, D-35043 Marburg, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Reutlinger
authors.affiliation: Division of Endocrinology, Diabetes, and Bone Diseases, Department of Medicine III, Technical University, D-01307 Dresden, Germany.
authors.forename: Lorenz C
authors.initials: LC
authors.lastname: Hofbauer
authors.affiliation: Department of Pathology, Philipps-University of Marburg, D-35043 Marburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Barth
authors.affiliation: Signaling and Transcription Laboratory, Department of Gastroenterology, Philipps-University of Marburg, D-35043 Marburg, Germany.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Gress
authors.affiliation: Laboratory of Epigenetics and Chromatin Dynamics, Departments of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905, and.
authors.forename: Gwen
authors.initials: G
authors.lastname: Lomberk
authors.affiliation: Laboratory of Epigenetics and Chromatin Dynamics, Departments of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905, and.
authors.forename: Raul
authors.initials: R
authors.lastname: Urrutia
authors.affiliation: Schulze Center for Novel Therapeutics, Division of Oncology Research, Mayo Clinic, Rochester, Minnesota 55904.
authors.forename: Martin E
authors.initials: ME
authors.lastname: Fernandez-Zapico
authors.affiliation: Signaling and Transcription Laboratory, Department of Gastroenterology, Philipps-University of Marburg, D-35043 Marburg, Germany,. Electronic address: ellenrie@med.uni-marburg.de.
authors.forename: Volker
authors.initials: V
authors.lastname: Ellenrieder
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000235:genetics; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D050071:Bone Density Conservation Agents / Q000494:pharmacology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D004164:Diphosphonates / Q000494:pharmacology*; D005260:Female; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D051379:Mice; D008819:Mice, Nude; D050778:NFATC Transcription Factors / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D054875:Ubiquitination / Q000187:drug effects / Q000235:genetics; D000077211:Zoledronic Acid
chemical_list: D000970:Antineoplastic Agents; D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D007093:Imidazoles; D050778:NFATC Transcription Factors; C494006:NFATC2 protein, human; D009363:Neoplasm Proteins; C494007:Nfatc2 protein, mouse; D000077211:Zoledronic Acid; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3