Genetic modifiers of the BRD4-NUT dependency of NUT midline carcinoma uncovers a synergism between BETis and CDK4/6is
- 1Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA;
- 2Department of Genetics, Program in Virology, Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115, USA;
- 3Harvard Medical School, Boston, Massachusetts 02115, USA;
- 4Ludwig Center at Harvard, Harvard Medical School, Boston, Massachusetts 02215, USA
- Corresponding author: selledge{at}genetics.med.harvard.edu
Abstract
Bromodomain and extraterminal (BET) domain inhibitors (BETis) show efficacy on NUT midline carcinoma (NMC). However, not all NMC patients respond, and responders eventually develop resistance and relapse. Using CRISPR and ORF expression screens, we systematically examined the ability of cancer drivers to mediate resistance of NMC to BETis and uncovered six general classes/pathways mediating resistance. Among these, we showed that RRAS2 attenuated the effect of JQ1 in part by sustaining ERK pathway function during BRD4 inhibition. Furthermore, overexpression of Kruppel-like factor 4 (KLF4), mediated BETi resistance in NMC cells through restoration of the E2F and MYC gene expression program. Finally, we found that expression of cyclin D1 or an oncogenic cyclin D3 mutant or RB1 loss protected NMC cells from BETi-induced cell cycle arrest. Consistent with these findings, cyclin-dependent kinase 4/6 (CDK4/6) inhibitors showed synergistic effects with BETis on NMC in vitro as well as in vivo, thereby establishing a potential two-drug therapy for NMC.
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Supplemental material is available for this article.
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Article published online ahead of print. Article and publication date are online at http://www.genesdev.org/cgi/doi/10.1101/gad.315648.118.
- Received April 12, 2018.
- Accepted July 17, 2018.
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