Predicting Novel Therapies and Targets: Regulation of Notch3 by the Bromodomain Protein BRD4

Abstract

Systematic approaches for accurate repurposing of targeted therapies are needed. We developed and aimed to biologically validate our therapy predicting tool (TPT) for the repurposing of targeted therapies for specific tumor types by testing the role of Bromodomain and Extra-Terminal motif inhibitors (BETi) in inhibiting BRD4 function and downregulating Notch3 signaling in ovarian cancer.Utilizing established ovarian cancer preclinical models, we carried out in vitro and in vivo studies with clinically relevant BETis to determine their therapeutic effect and impact on Notch3 signaling.Treatment with BETis or siRNA-mediated BRD4 knockdown resulted in decreased cell viability, reduced cell proliferation, and increased cell apoptosis in vitro. In vivo studies with orthotopic mouse models demonstrated that treatment with BETi decreased tumor growth. In addition, knockdown of BRD4 with doxycycline-inducible shRNA increased survival up to 50% (P < 0.001). Treatment with either BETis or BRD4 siRNA decreased Notch3 expression both in vitro and in vivo. BRD4 inhibition also decreased the expression of NOTCH3 targets, including HES1. Chromatin immunoprecipitation revealed that BRD4 was present at the NOTCH3 promoter.Our findings provide biological validation for the TPT by demonstrating that BETis can be an effective therapeutic agent for ovarian cancer by downregulating Notch3 expression.The TPT could rapidly identify candidate drugs for ovarian or other cancers along with novel companion biomarkers.

Ameliorative effect of a quinazoline-based bromodomain inhibitor, CN210, on experimentally-induced Crohn’s disease-like murine ileitis via inhibition of inflammatory cytokine expression

“…We previously reported that CN210 potently inhibited bromodomains of BET proteins with K d values ranging from 11 nM to 200 nM [17, 28]. In the present study, we demonstrated that CN210 also inhibited the bromodomains of two paralogous HATs, CBP and p300, with K d values of 260 nM and 190 nM, respectively (Table 1) as compared to the previously reported K d values of 70 nM for BRD4 [17].…”

Evaluation of FGFR1 as a diagnostic biomarker for ovarian cancer using TCGA and GEO datasets

“…Targeted treatments and immunohistochemistry offer the hope of improved treatments for OC patients in the future. Moreover, identifying biomarkers for targeted treatments is important for effective cancer diagnosis and treatment ( Shivange et al, 2018 ; Villar-Prados et al, 2018 ). RNA sequencing is an accurate method used to identify such biomarkers ( Coenen-Stass et al, 2018 ; Jiang et al, 2018 ).…”

“…The targeted treatment of OC plays an increasingly important role in the comprehensive treatment of OC and new tumor treatment strategies depend on the search for new targets ( Huang et al, 2018 ; Shivange et al, 2018 ; Villar-Prados et al, 2018 ; Zhai et al, 2018 ). With the development of sequencing technology and acquirement of a large amount of biological data, bioinformatics can be used to understand and find new biomarkers of tumor ( Yang et al, 2020 ; Wu et al, 2019 ; Tao et al, 2019 ).…”

MiR-596 activated by EP300 controls the tumorigenesis in epithelial ovarian cancer by declining BRD4 and KPNA4

“…For instance, NSD3-BRD4-CHD8 pathway functions in pelvic high-grade serous carcinomas originated from tubo-ovarian and endometrial [33]. Of note, BRD4 is predicted as a novel therapeutic target for regulating Notch3 signaling in OC [34]. Also, MiR-3619-5p inhibits cell proliferation and cisplatin resistance in cutaneous squamous cell cancer by targeting KPNA4 [35].…”