Abstract 4689: Co-treatment of MEKi and BRD4 inhibitors lead to synergistic repression of MYC-associated enhancer RNAs

Recent evidence suggests that co-treatment with BRD4 and MEK inhibitors can lead to synergistic suppression of MAPK signaling, however, little is known about the mechanism of action of this synergy. In a triple negative breast cancer cell line model, we harvested nascent RNA at 45 minutes following repression of BRD4 and MEK via a variant of the precision run-on followed by sequencing (PRO-seq) assay. We noted dose-dependent repression of enhancer RNAs over MYC binding sites as well as enhancer RNAs upstream known ERK targets such as DUSP6. Using new machine learning techniques, we were able to link synergy-specific enhancer RNAs to their target genes. This work will inform on new methods for patient stratification and biomarker selection of the BETi and MEKi treatment regimes. Citation Format: Joseph Azofeifa, Joel Basken, Maria Lai, Ryan Langendorf, Laura Norris, Tim Read, Adam Robbins-Pianka. Co-treatment of MEKi and BRD4 inhibitors lead to synergistic repression of MYC-associated enhancer RNAs [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4689.