title: Hypoxia induced E-cadherin involving regulators of Hippo pathway due to HIF-1α stabilization/nuclear translocation in bone metastasis from breast carcinoma.
abstract: The present study deals with the molecular mechanisms involved in the regulation of E-cadherin expression under hypoxia, because the adjustment of the amount of E-cadherin due to physical stimuli of the microenvironment might influence the colonization of metastasis to skeleton. We analyzed the effect of 1% oxygen tension, that is similar to that encountered in the bone marrow by metastatic cells spreading from breast carcinoma. The purpose was to evaluate the hypoxia-orchestrated control of E-cadherin transactivation via hypoxia inducible factor-1 (HIF-1) and peroxisome proliferator activated receptor-γ (PPARγ), and the involvement of Hippo pathway members, as regulators of transcription factors. To give a translational significance to the study, we took into consideration human pair-matched ductal breast carcinoma and bone metastasis: E-cadherin and Wwox were expressed in bone metastasis but not in breast carcinoma, while HIF-1α and TAZ seemed localized principally in nuclei of metastasis and were found in all cell compartments of breast carcinoma. A close examination of the regulatory mechanisms underlying E-cadherin expression in bone metastasis was done in 1833 clone derived from MDA-MB231 cells. Hypoxia induced E-cadherin only in 1833 clone, but not in parental cells, through HIF-1 and PPARγ activities, while Wwox decreased. Since Wwox was highly expressed in bone metastasis, the effect of ectopic Wwox was evaluated, and we showed E-cadherin transactivation and enhanced invasiveness in WWOX transfected 1833 cells. Also, hypoxia was additive with ectopic Wwox remarkably enhancing HIF-1α nuclear shuttle and accumulation due to the lengthening of the half-life of HIF-1α protein; under this experimental condition HIF-1α appeared as a slower migrated band compared with control, in agreement with the phosphorylation state. The in vitro data strongly supported the almost exclusive presence of HIF-1α in nuclei of human-bone metastasis. Thus, we identified Wwox as a novel molecule in the HIF-1α-HDM2 regulatory loop, necessary for the dynamic regulation of the HIF-1α amount, and we suggested that the reduction of endogenous Wwox free pool under hypoxia might also be due to the interaction with HDM2, sequestering the E3 ubiquitin ligase. We highlighted the importance of nuclear HIF-1α in the biology of metastasis for the mesenchymal-epithelial transition: this phenotype was regulated by Wwox plus hypoxia through E-cadherin target gene, playing a pivotal role in bone metastasis colonization.
authors.affiliation: Istituto Ortopedico Galeazzi, IRCCS, Milano, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Maroni
authors.affiliation: Dipartiimento di Scienze Biomediche per la Salute, Molecular Pathology Laboratory, Università degli Studi di Milano, Milano, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Matteucci
authors.affiliation: Istituto Ortopedico Galeazzi, IRCCS, Milano, Italy; Dipartiimento di Scienze Biomediche per la Salute, Molecular Pathology Laboratory, Università degli Studi di Milano, Milano, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Drago
authors.affiliation: Istituto Ortopedico Galeazzi, IRCCS, Milano, Italy; Dipartiimento di Scienze Biomediche per la Salute, Molecular Pathology Laboratory, Università degli Studi di Milano, Milano, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Banfi
authors.affiliation: Dipartiimento di Scienze Biomediche per la Salute, Molecular Pathology Laboratory, Università degli Studi di Milano, Milano, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Bendinelli
authors.affiliation: Dipartiimento di Scienze Biomediche per la Salute, Molecular Pathology Laboratory, Università degli Studi di Milano, Milano, Italy. Electronic address: a.desiderio@unimi.it.
authors.forename: Maria Alfonsina
authors.initials: MA
authors.lastname: Desiderio
mesh_terms: D000217:Acyltransferases; D001859:Bone Neoplasms / Q000556:secondary*; D001943:Breast Neoplasms / Q000473:pathology*; D015820:Cadherins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D018270:Carcinoma, Ductal, Breast / Q000556:secondary*; D015687:Cell Hypoxia / Q000502:physiology; D045744:Cell Line, Tumor; D058750:Epithelial-Mesenchymal Transition / Q000502:physiology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D000090683:Hippo Signaling Pathway; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D047495:PPAR gamma / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism; D015533:Transcriptional Activation; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D000074584:WW Domain-Containing Oxidoreductase
chemical_list: D015820:Cadherins; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D047495:PPAR gamma; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D010088:Oxidoreductases; D000074584:WW Domain-Containing Oxidoreductase; C486071:WWOX protein, human; D000217:Acyltransferases; C108675:TAFAZZIN protein, human; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D044767:Ubiquitin-Protein Ligases; D017346:Protein Serine-Threonine Kinases
keywords: Bone metastasis; E-cadherin; HIF-1; Hypoxia; Wwox