Acetylation of CCAR2 Establishes a BET/BRD9 Acetyl Switch in Response to Combined Deacetylase and Bromodomain Inhibition.

Abstract

There continues to be interest in targeting epigenetic "readers, writers, and erasers" for the treatment of cancer and other pathologies. However, a mechanistic understanding is frequently lacking for the synergy observed when combining deacetylase and bromodomain inhibitors. Here we identify cell cycle and apoptosis regulator 2 (CCAR2) as an early target for acetylation in colon cancer cells treated with sulforaphane. N-terminal acetylation of CCAR2 diminished its interactions with histone deacetylase 3 and β-catenin, interfering with Wnt coactivator functions of CCAR2, including in cells harboring genetically encoded CCAR2 acetylation. Protein domain arrays and pull-down assays identified acetyl "reader" proteins that recognized CCAR2 acetylation sites, including BRD9 and members of the bromodomain and extraterminal domain (BET) family. Treatment with the BET inhibitor JQ1 synergized with sulforaphane in colon cancer cells and suppressed tumor development effectively in a preclinical model of colorectal cancer. Studies with sulforaphane+JQ1 in combination implicated a BET/BRD9 acetyl switch and a shift in the pool of acetyl "reader" proteins in favor of BRD9-regulated target genes. SIGNIFICANCE: These results highlight the competition that exists among the "readers" of acetylated histone and nonhistone proteins and provide a mechanistic basis for potential new therapeutic avenues involving epigenetic combination treatments.

• Authors: Praveen Rajendran, Gavin Johnson, Li Li, Ying-Shiuan Chen, Mohaiza Dashwood, Nhung Nguyen, Ahmet Ulusan, Furkan Ertem, Mutian Zhang, Jia Li, Deqiang Sun, Yun Huang, Shan Wang, Hon-Chiu Leung, David Lieberman, Laura Beaver, Emily Ho, Mark Bedford, Kyle Chang, Eduardo Vilar, Roderick Dashwood
• Journal: Cancer research (Cancer Res) Vol. 79 Issue 5 Pg. 918-927 (03 01 2019) ISSN: 1538-7445 [Electronic] United States
• PMID: 30643017 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: ©2019 American Association for Cancer Research.

Chemical References

• (+)-JQ1 compound
• Adaptor Proteins, Signal Transducing
• Azepines
• BRD9 protein, human
• CCAR2 protein, human
• CTNNB1 protein, human
• Histone Deacetylase Inhibitors
• Histones
• Isothiocyanates
• Proteins
• Sulfoxides
• Transcription Factors
• Triazoles
• beta Catenin
• bromodomain and extra-terminal domain protein, human
• Histone Deacetylases
• histone deacetylase 3
• sulforaphane

Topics

• Acetylation (drug effects)
• Adaptor Proteins, Signal Transducing (genetics, metabolism)
• Animals
• Antineoplastic Combined Chemotherapy Protocols (pharmacology)
• Azepines (administration & dosage, pharmacology)
• Cell Line, Tumor
• Colorectal Neoplasms (drug therapy, genetics, metabolism)
• Epigenesis, Genetic
• HCT116 Cells
• Histone Deacetylase Inhibitors (administration & dosage, pharmacology)
• Histone Deacetylases (metabolism)
• Histones (metabolism)
• Humans
• Isothiocyanates (administration & dosage, pharmacology)
• Male
• Mice
• Mice, Nude
• Proteins (antagonists & inhibitors, metabolism)
• Random Allocation
• Sulfoxides
• Transcription Factors (metabolism)
• Triazoles (administration & dosage, pharmacology)
• Xenograft Model Antitumor Assays
• beta Catenin (metabolism)