Epidermal growth factor-induced heparanase nucleolar localization augments DNA topoisomerase I activity in brain metastatic breast cancer

Lixin Zhang, Peggy Sullivan, Julie Suyama, Dario Marchetti

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Identification of molecular mechanisms responsible for brain metastatic breast cancer (BMBC) is imperative to develop novel therapies. However, current understanding of the molecular circuitry that governs BMBC dissemination remains fragmentary. Heparanase (HPSE) is the only functional mammalian endoglycosidase whose activity correlates with cancer metastasis, angiogenesis, and the reduced postoperative survival of cancer patients, making it an active target for anticancer therapeutics. We hypothesized that human epidermal growth factor receptor 2 (HER2)/epidermal growth factor receptor (EGFR) activation promotes HPSE function in human BMBC. To address this, we examined HPSE content, activity, and intracellular trafficking in a HER2/EGFR-expressing BMBC model system and show that HPSE is present, functional, and correlates with HER2 status. Further, we showed that EGF induced nucleolar translocation of HPSE in these cells in a doseand time-dependent manner upon activation of HER2/EGFR. Knockdowns of HER2/EGFR by small interference RNA abolished EGF-induced HPSE nucleolar translocalization. It was also noted that nucleolar HPSE modulates DNA topoisomerase I (Topo I), an enzyme that is highly present in nucleoli, essential for DNA replication and transcription in a variety of tumors, and inhibited by heparan sulfate. Evidence is provided that HPSE can regulate Topo I activity, which subsequently affects BMBC cell proliferation. Finally, we showed that the nucleolar presence of HPSE with Topo I colocalization is detected only in HER2-overexpressing BMBC patient specimens. Altogether, these findings support the notion that HPSE is a critical downstream target of HER2 mechanisms driving BMBC and is potentially relevant for BMBC therapeutic interventions.

Original languageEnglish (US)
Pages (from-to)278-290
Number of pages13
JournalMolecular Cancer Research
Volume8
Issue number2
DOIs
StatePublished - Feb 2010

ASJC Scopus subject areas

  • Molecular Biology
  • Oncology
  • Cancer Research

Fingerprint Dive into the research topics of 'Epidermal growth factor-induced heparanase nucleolar localization augments DNA topoisomerase I activity in brain metastatic breast cancer'. Together they form a unique fingerprint.

Cite this