title: Knockdown of prolyl-4-hydroxylase domain 2 inhibits tumor growth of human breast cancer MDA-MB-231 cells by affecting TGF-β1 processing.
abstract: The prolyl-4-hydroxylase domain 1-3 (PHD1-3) enzymes are regulating the protein stability of the α-subunit of the hypoxia-inducible factor-1 (HIF-1), which mediates oxygen-dependent gene expression. PHD2 is the main isoform regulating HIF-1α hydroxylation and thus stability in normoxia. In human cancers, HIF-1α is overexpressed as a result of intratumoral hypoxia which in turn promotes tumor progression. The role of PHD2 for tumor progression is in contrast far from being thoroughly understood. Therefore, we established PHD2 knockdown clones of MDA-MB-231 breast cancer cells and analyzed their tumor-forming potential in a SCID mouse model. Tumor progression was significantly impaired in the PHD2 knockdown MDA-MB-231 cells, which could be partially rescued by re-establishing PHD2 expression. In a RNA profile screen, we identified the secreted phosphoprotein 1 (SPP1) as one target, which is differentially regulated as a consequence of the PHD2 knockdown. Knockdown of PHD2 drastically reduced the SPP1 expression in MDA-MB-231 cells. A correlation of SPP1 and PHD2 expression was additionally verified in 294 invasive breast cancer biopsies. In subsequent analyses, we identified that PHD2 alters the processing of transforming growth factor (TGF)-β1, which is highly involved in SPP1 expression. The altered processing capacity was associated with a dislocation of the pro-protein convertase furin. Thus, our data demonstrate that in MDA-MB-231 cells PHD2 might affect tumor-relevant TGF-β1 target gene expression by altering the TGF-β1 processing capacity.
authors.affiliation: Department of Cardiovascular Physiology, University Medical Center, Georg-August University of Göttingen, D-37073 Göttingen, Germany.
authors.forename: Marieke
authors.initials: M
authors.lastname: Wottawa
authors.forename: Pia
authors.initials: P
authors.lastname: Leisering
authors.forename: Melanie von
authors.initials: Mv
authors.lastname: Ahlen
authors.forename: Moritz
authors.initials: M
authors.lastname: Schnelle
authors.forename: Sabine
authors.initials: S
authors.lastname: Vogel
authors.forename: Cordula
authors.initials: C
authors.lastname: Malz
authors.forename: Mattia Renato
authors.initials: MR
authors.lastname: Bordoli
authors.forename: Gieri
authors.initials: G
authors.lastname: Camenisch
authors.forename: Amke
authors.initials: A
authors.lastname: Hesse
authors.forename: Joanna
authors.initials: J
authors.lastname: Napp
authors.forename: Frauke
authors.initials: F
authors.lastname: Alves
authors.forename: Glen
authors.initials: G
authors.lastname: Kristiansen
authors.forename: Katja
authors.initials: K
authors.lastname: Farhat
authors.forename: Dörthe Magdalena
authors.initials: DM
authors.lastname: Katschinski
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D004195:Disease Models, Animal; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D051379:Mice; D053495:Osteopontin / Q000235:genetics; D011393:Procollagen-Proline Dioxygenase / Q000235:genetics*; D015398:Signal Transduction; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D047368:Tumor Burden / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: C506895:SPP1 protein, human; D053773:Transforming Growth Factor beta1; D053495:Osteopontin; C490190:EGLN1 protein, human; D011393:Procollagen-Proline Dioxygenase; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases