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Title: HDAC inhibitors suppress c-Jun/Fra-1-mediated proliferation through transcriptionally downregulating MKK7 and Raf1 in neuroblastoma cells
Authors: He, Weiwen
Wu, Yanna
Tang, Xiaomei
Xia, Yong
He, Guozhen
Min, Zhiqun
Li, Chun
Xiong, Shiqiu
Shi, Zhi
Lu, Yongjian
Yuan, Zhongmin
First Published: 30-Dec-2015
Publisher: Impact Journals
Citation: Oncotarget, 2015, 7 (6), pp. 6727-6747
Abstract: Activator protein 1 (AP-1) is a transcriptional factor composed of the dimeric members of bZIP proteins, which are frequently deregulated in human cancer cells. In this study, we aimed to identify an oncogenic AP-1 dimer critical for the proliferation of neuroblastoma cells and to investigate whether histone deacetylase inhibitors (HDACIs), a new generation of anticancer agents, could target the AP-1 dimer. We report here that HDACIs including trichostatin A, suberoylanilidehydroxamic acid, valproic acid and M344 can transcriptionally suppress both c-Jun and Fra-1, preceding their inhibition of cell growth. c-Jun preferentially interacting with Fra-1 as a heterodimer is responsible for AP-1 activity and critical for cell growth. Mechanistically, HDACIs suppress Fra-1 expression through transcriptionally downregulating Raf1 and subsequently decreasing MEK1/2-ERK1/2 activity. Unexpectedly, HDACI treatment caused MKK7 downregulation at both the protein and mRNA levels. Deletion analysis of the 5′-flanking sequence of the MKK7 gene revealed that a major element responsible for the downregulation by HDACI is located at -149 to -3 relative to the transcriptional start site. Knockdown of MKK7 but not MKK4 remarkably decreased JNK/c-Jun activity and proliferation, whereas ectopic MKK7-JNK1 reversed HDACI-induced c-Jun suppression. Furthermore, suppression of both MKK-7/c-Jun and Raf-1/Fra-1 activities was involved in the tumor growth inhibitory effects induced by SAHA in SH-SY5Y xenograft mice. Collectively, these findings demonstrated that c-Jun/Fra-1 dimer is critical for neuroblastoma cell growth and that HDACIs act as effective suppressors of the two oncogenes through transcriptionally downregulating MKK7 and Raf1.
DOI Link: 10.18632/oncotarget.6797
ISSN: 1949-2553
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © the authors, 2015. This is an open-access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Appears in Collections:Published Articles, Dept. of Molecular and Cell Biology

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