NOTCH-1 and NOTCH-4 are novel gene targets of PEA3 in breast cancer: novel therapeutic implications.

Abstract

INTRODUCTION:

Women with triple-negative breast cancer have the worst prognosis, frequently present with metastatic tumors and have few targeted therapy options. Notch-1 and Notch-4 are potent breast oncogenes that are overexpressed in triple-negative and other subtypes of breast cancer. PEA3, an ETS transcription factor, is also overexpressed in triple-negative and other breast cancer subtypes. We investigated whether PEA3 could be the critical transcriptional activator of Notch receptors in MDA-MB-231 and other breast cancer cells.

METHODS:

Real-time PCR and Western blot analysis were performed to detect Notch-1, Notch-2, Notch-3 and Notch-4 receptor expression in breast cancer cells when PEA3 was knocked down by siRNA. Chromatin immunoprecipitation was performed to identify promoter regions for Notch genes that recruited PEA3. TAM-67 and c-Jun siRNA were used to identify that c-Jun was necessary for PEA3 enrichment on the Notch-4 promoter. A Notch-4 luciferase reporter was used to confirm that endogenous PEA3 or AP-1 activated the Notch-4 promoter region. Cell cycle analysis, trypan blue exclusion, annexin V flow cytometry, colony formation assay and an in vivo xenograft study were performed to determine the biological significance of targeting PEA3 via siRNA, Notch signaling via a γ-secretase inhibitor, or both.

RESULTS:

Herein we provide new evidence for transcriptional regulation of Notch by PEA3 in breast cancer. PEA3 activates Notch-1 transcription in MCF-7, MDA-MB-231 and SKBr3 breast cancer cells. PEA3 activates Notch-4 transcription in MDA-MB-231 cells where PEA3 levels are endogenously high. In SKBr3 and BT474 breast cancer cells where PEA3 levels are low, overexpression of PEA3 increases Notch-4 transcripts. Chromatin immunoprecipitation confirmed the enrichment of PEA3 on Notch-1 and Notch-4 promoters in MDA-MB-231 cells. PEA3 recruitment to Notch-1 was AP-1-independent, whereas PEA3 recruitment to Notch-4 was c-JUN-dependent. Importantly, the combined inhibition of Notch signaling via a γ-secretase inhibitor (MRK-003 GSI) and knockdown of PEA3 arrested growth in the G1 phase, decreased both anchorage-dependent and anchorage-independent growth and significantly increased apoptotic cells in vitro. Moreover, either PEA3 knockdown or MRK-003 GSI treatment significantly reduced tumor growth of MDA-MB-231 xenografts in vivo.

CONCLUSIONS:

Taken together, the results from this study demonstrate for the first time that Notch-1 and Notch-4 are novel transcriptional targets of PEA3 in breast cancer cells. Targeting of PEA3 and/or Notch pathways might provide a new therapeutic strategy for triple-negative and possibly other breast cancer subtypes.

• Authors: Anthony G Clementz, Allison Rogowski, Kinnari Pandya, Lucio Miele, Clodia Osipo
• Journal: Breast cancer research : BCR (Breast Cancer Res) Vol. 13 Issue 3 Pg. R63 (Jun 14 2011) ISSN: 1465-542X [Electronic] England
• PMID: 21679465 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• NOTCH1 protein, human
• NOTCH2 protein, human
• NOTCH3 protein, human
• NOTCH4 protein, human
• Peptide Fragments
• Proto-Oncogene Proteins
• Proto-Oncogene Proteins c-jun
• RNA, Small Interfering
• Receptor, Notch1
• Receptor, Notch2
• Receptor, Notch3
• Receptor, Notch4
• Receptors, Notch
• TAM67 peptide
• Transcription Factor AP-1
• Transcription Factors
• transcription factor PEA3
• JNK Mitogen-Activated Protein Kinases
• Amyloid Precursor Protein Secretases

Topics

• Amyloid Precursor Protein Secretases (antagonists & inhibitors)
• Breast Neoplasms (genetics, metabolism, pathology)
• Cell Cycle
• Cell Line, Tumor
• Cell Proliferation
• Chromatin Immunoprecipitation
• Female
• Gene Expression Regulation, Neoplastic
• Humans
• JNK Mitogen-Activated Protein Kinases (metabolism)
• Peptide Fragments (genetics)
• Promoter Regions, Genetic
• Proto-Oncogene Proteins (genetics, metabolism)
• Proto-Oncogene Proteins c-jun (genetics)
• RNA Interference
• RNA, Small Interfering
• Receptor, Notch1 (genetics, metabolism)
• Receptor, Notch2 (genetics, metabolism)
• Receptor, Notch3
• Receptor, Notch4
• Receptors, Notch (genetics, metabolism)
• Signal Transduction
• Transcription Factor AP-1 (genetics, metabolism)
• Transcription Factors (genetics, metabolism)
• Transcription, Genetic