Nuclear co-localization and functional interaction of COX-2 and HIF-1α characterize bone metastasis of human breast carcinoma.
The aim of this article is to identify nuclear co-localization of COX-2 and HIF-1α in human-bone metastasis of breast cancer, index of transcriptionally activated cells and functional for gene expression. In particular, we verified whether hypoxia exerted a direct role on metastasis-gene expression or through COX-2 signaling, due to the relevance for clinical implications to individuate molecular targets for diagnosis and therapy. The experiments were performed in vitro with two metastatic clones, 1833 and MDA-231BO, and the parental MDA-MB231 cells, in vivo (1833-xenograft model), and in human-bone metastasis specimens. In 1833 cells in vitro, COX-2 signaling pathway was critical for nuclear HIF-1α-protein expression/translocation, mechanisms determining HIF-1 activity and gene expression. The data were corroborated by immunohistochemistry in human-bone metastasis specimens. COX-2 and HIF-1α showed wide co-localization in the nucleus, indicative of COX-2-nuclear import in transcriptionally activated metastatic cells and consistent with COX-2-HIF-1α functional interaction. A network of microenvironmental signals controlled COX-2 induction and HIF-1 activation downstream. In fact, hypoxia through HGF and TGF-β1 autoregulatory loops triggered a specific array of transcription factors responsible for COX-2 transactivation. The novelty was that HGF and TGF-β1 biological signals were produced by hypoxic metastatic cells and, therefore, the microenvironment seemed to be modified by metastatic-cell engraftment in the bone. In agreement, HIF-1α expression in bone marrow supportive cells occurred in metastasis-bearing animals. Altogether, the data supported the pre-metastatic-niche theory. Our observations might be useful to design therapies against bone metastasis, by affecting the phenotype changes of metastatic cells occurring at the secondary growth site through COX-2-HIF-1 interaction.
Istituto Ortopedico Galeazzi-IRCCS, Via Riccardo Galeazzi, 4-20161, Milan, Italy.
Paola
P
Maroni
Emanuela
E
Matteucci
Alessandro
A
Luzzati
Giuseppe
G
Perrucchini
Paola
P
Bendinelli
Maria Alfonsina
MA
Desiderio
D000818:Animals; D015153:Blotting, Western; D001859:Bone Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D001943:Breast Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D002277:Carcinoma / Q000201:enzymology* / Q000235:genetics / Q000556:secondary; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000201:enzymology* / Q000473:pathology; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D051379:Mice; D015398:Signal Transduction; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000235:genetics; D059016:Tumor Microenvironment
C066855:HGF protein, human; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C508960:TGFB1 protein, human; D053773:Transforming Growth Factor beta1; D017228:Hepatocyte Growth Factor; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human