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Title: Dual Targeting of Bromodomain and Extraterminal Domain Proteins, and WNT or MAPK Signaling, Inhibits c-MYC Expression and Proliferation of Colorectal Cancer Cells.
Austin Authors: Tögel, Lars;Nightingale, Rebecca;Chueh, Anderly C;Jayachandran, Aparna;Tran, Hoanh;Phesse, Toby;Wu, Rui;Sieber, Oliver M;Arango, Diego;Dhillon, Amardeep S;Dawson, Mark A;Diez-Dacal, Beatriz;Gahman, Timothy C;Filippakopoulos, Panagis;Shiau, Andrew K;Mariadason, John M 
Affiliation: Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
Olivia Newton-John Cancer Research Institute, Heidelberg, Victoria, Australia
Ludwig Institute for Cancer Research, Melbourne, Victoria, Australia
La Trobe University School of Cancer Medicine, Melbourne, Victoria, Australia
CIBBIM-Nanomedicine, Vall d'Hebron University Hospital Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain
Peter MacCallum Cancer Institute, Melbourne, Victoria, Australia
Ludwig Institute for Cancer Research and UK and Structural Genomics Consortium, Oxford, United Kingdom
Small Molecule Discovery Program, Ludwig Institute for Cancer Research, La Jolla, California
Issue Date: Jun-2016 2016-03-16
Publication information: Molecular cancer therapeutics 2016; 15(6): 1217-26
Abstract: Inhibitors of the bromodomain and extraterminal domain (BET) protein family attenuate the proliferation of several tumor cell lines. These effects are mediated, at least in part, through repression of c-MYC. In colorectal cancer, overexpression of c-MYC due to hyperactive WNT/β-catenin/TCF signaling is a key driver of tumor progression; however, effective strategies to target this oncogene remain elusive. Here, we investigated the effect of BET inhibitors (BETi) on colorectal cancer cell proliferation and c-MYC expression. Treatment of 20 colorectal cancer cell lines with the BETi JQ1 identified a subset of highly sensitive lines. JQ1 sensitivity was higher in cell lines with microsatellite instability but was not associated with the CpG island methylator phenotype, c-MYC expression or amplification status, BET protein expression, or mutation status of TP53, KRAS/BRAF, or PIK3CA/PTEN Conversely, JQ1 sensitivity correlated significantly with the magnitude of c-MYC mRNA and protein repression. JQ1-mediated c-MYC repression was not due to generalized attenuation of β-catenin/TCF-mediated transcription, as JQ1 had minimal effects on other β-catenin/TCF target genes or β-catenin/TCF reporter activity. BETi preferentially target super-enhancer-regulated genes, and a super-enhancer in c-MYC was recently identified in HCT116 cells to which BRD4 and effector transcription factors of the WNT/β-catenin/TCF and MEK/ERK pathways are recruited. Combined targeting of c-MYC with JQ1 and inhibitors of these pathways additively repressed c-MYC and proliferation of HCT116 cells. These findings demonstrate that BETi downregulate c-MYC expression and inhibit colorectal cancer cell proliferation and identify strategies for enhancing the effects of BETi on c-MYC repression by combinatorial targeting the c-MYC super-enhancer. Mol Cancer Ther; 15(6); 1217-26. ©2016 AACR.
DOI: 10.1158/1535-7163.MCT-15-0724
PubMed URL: 26983878
Type: Journal Article
Appears in Collections:Journal articles

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