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PNAS 110 (5): 1714-1719

Copyright © 2013 by the National Academy of Sciences.

BIOLOGICAL SCIENCES / CELL BIOLOGY

High throughput kinase inhibitor screens reveal TRB3 and MAPK-ERK/TGFβ pathways as fundamental Notch regulators in breast cancer

Julia Izrailita,b, Hal K. Bermana,c, Alessandro Dattid,e, Jeffrey L. Wranad, and Michael Reedijka,b,f,1

aCampbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, ON, Canada M5G 2M9; bDepartment of Medical Biophysics, University of Toronto, Ontario Cancer Institute, Princess Margaret Hospital, Toronto, ON, Canada M5G 2M9; cDepartment of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada M5S 1A8; dCenter for Systems Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada M5G 1X5; eDepartment of Experimental Medicine and Biochemical Sciences, University of Perugia, 06100 Perugia, Italy; and fDepartment of Surgical Oncology, Princess Margaret Hospital, University Health Network, Toronto, ON, Canada M5G 2M9

Edited by Tak W. Mak, The Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute at Princess Margaret Hospital, University Health Network, Toronto, ON, Canada, and approved December 12, 2012 (received for review August 20, 2012)

Abstract: Expression of the Notch ligand Jagged 1 (JAG1) and Notch activation promote poor-prognosis in breast cancer. We used high throughput screens to identify elements responsible for Notch activation in this context. Chemical kinase inhibitor and kinase-specific small interfering RNA libraries were screened in a breast cancer cell line engineered to report Notch. Pathway analyses revealed MAPK-ERK signaling to be the predominant JAG1/Notch regulator and this was supported by gene set enrichment analyses in 51 breast cancer cell lines. In accordance with the chemical screen, kinome small interfering RNA high throughput screens identified Tribbles homolog 3 (TRB3), a known regulator of MAPK-ERK, among the most significant hits. We demonstrate that TRB3 is a master regulator of Notch through the MAPK-ERK and TGFβ pathways. Complementary in vitro and in vivo studies underscore the importance of TRB3 for tumor growth. These data demonstrate a dominant role for TRB3 and MAPK-ERK/TGFβ pathways as Notch regulators in breast cancer, establishing TRB3 as a potential therapeutic target.

Author contributions: J.I. and M.R. designed research; J.I. performed research; A.D. and J.L.W. contributed new reagents/analytic tools; J.I., H.K.B., A.D., and M.R. analyzed data; and J.I. and M.R. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1214014110/-/DCSupplemental.

1To whom correspondence should be addressed. E-mail: michael.reedijk{at}uhn.on.ca.

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