Nuclear co-localization and functional interaction of COX-2 and HIF-1α characterize bone metastasis of human breast carcinoma

Paola Maroni, Emanuela Matteucci, Alessandro Luzzati, Giuseppe Perrucchini, Paola Bendinelli, Maria Alfonsina Desiderio

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish
Pages (from-to)433-450
Number of pages18
JournalBreast Cancer Research and Treatment
Volume129
Issue number2
DOIs
Publication statusPublished - Sep 2011

Keywords

  • Bone metastasis
  • Bone microenvironment
  • Breast cancer
  • COX-2
  • HIF-1

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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