The bromodomain BET inhibitor JQ1 suppresses tumor angiogenesis in models of childhood sarcoma

Hemant K. Bid, Doris A. Phelps, Linlin Xaio, Denis C. Guttridge, Jiayuh Lin, Cheryl London, Laurence H. Baker, Xiaokui Mo, Peter J. Houghton

Research output: Contribution to journalArticlepeer-review

40 Scopus citations

Abstract

The bromodomain and extra-terminal domain inhibitor JQ1 has marked antitumor activity against several hematologic malignancies as well as solid tumor models. Here, we investigated its activity in vitro and in vivo against models of childhood rhabdomyosarcoma and Ewing sarcoma. In vitro, JQ1 (but not the inactive enantiomer JQ1R) inhibited cell proliferation and increased G1 fraction of cells, although there was no correlation between cell line sensitivity and suppression of c-MYC or MYCN. In vivo, xenografts showed significant inhibition of growth during the period of treatment, and rapid regrowth after treatment was stopped, activity typical of antiangiogenic agents. Furthermore, xenografts derived from cell lines intrinsically resistant or sensitive to JQ1 in vitro had similar sensitivity in vivo as xenografts. Further investigation showed that JQ1 reduced tumor vascularization. This was secondary to both drug-induced downregulation of tumorderived growth factors and direct effects of JQ1 on vascular elements. JQ1 suppressed VEGF-stimulated vascularization of Matrigel plugs in mice, and in vitro suppressed differentiation, proliferation, and invasion of human umbilical cord vascular endothelial cells (HUVEC). In HUVECs, JQ1 partially suppressed c-MYC levels, but dramatically reduced AP-1 levels and activity through suppression of the AP-1-associated protein FOSL1. Our data suggest that the antitumor activity of JQ1 in these sarcoma models is largely a consequence of its antiangiogenic activity.

Original languageEnglish (US)
Pages (from-to)1018-1028
Number of pages11
JournalMolecular cancer therapeutics
Volume15
Issue number5
DOIs
StatePublished - May 2016

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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