MP130 - Apabetalone (RVX-208) Reduces ACE2 Expression in Human Cell Culture Systems, Which Could Attenuate SARS-CoV-2 Viral Entry

In Session:          Mechanisms of SARS-CoV-2 Infection

Author Block: Dean Gilham, Resverlogix Corp, Calgary, AB, Canada; Li Fu, Resverlogix Corp., Calgary, AB, Canada; Laura Miyoko Tsujikawa, Brooke Rakai, Sylwia Wasiak, Stephanie Stotz, Christopher Sarsons, Resverlogix Corp, Calgary, AB, Canada; Michael Sweeney, Jan JOHANSSON, Resverlogix Corp, San Francisco, CA; Norman Wong, Ewelina Kulikowski, Resverlogix Corp, Calgary, AB, Canada

Disclosure Block: D. Gilham: Employment; Significant; Resverlogix. Stock Shareholder; Significant; Resverlogix. L. Fu: Employment; Modest; Resverlogix Corp. L.M. Tsujikawa: Employment; Significant; Resverlogix. Stock Shareholder; Modest; Resverlogix. B. Rakai: Employment; Significant; Resverlogix. Stock Shareholder; Significant; Resverlogix. S. Wasiak: Employment; Significant; Resverlogix. Stock Shareholder; Modest; Resverlogix. S. Stotz: Employment; Significant; Resverlogix. M. Sweeney: Employment; Significant; Resverlogix. J. Johansson: Employment; Significant; Resverlogix. N. Wong: Employment; Significant; Resverlogix Corp. E. Kulikowski: Employment; Significant; Resverlogix Corp. Stock Shareholder; Significant; Resverlogix Corp.

Introduction: Apabetalone is an orally available small molecule that affects gene transcription by inhibiting BET protein interactions with acetylated histones and transcription factors. Apabetalone is in late stage clinical development for the treatment of cardiovascular disease (CVD). Clinical trials show apabetalone is well tolerated and has a favorable safety profile. Recent evidence indicates this drug could be repurposed to treat COVID-19 by reducing expression of the angiotensin converting enzyme 2 (ACE2) receptor that is essential for SARS-CoV-2 viral entry and/or disrupting viral protein E interaction with BET proteins. The spike protein of SARS-CoV-2 engages with human ACE2 expressed in multiple organs such as lung, liver, kidney, heart and intestine to initiate infection in host cells. Ultimately, the infection leads to life threatening complications in COVID-19 patients.

Hypothesis: Apabetalone downregulates ACE2 expression to protect human cells from SARS-CoV-2.

Methods: Primary human kidney tubular epithelial cells (RPTEC) were stimulated with TNFα and co-treated with apabetalone overnight. Primary human hepatocytes (PHH) and the hepatoma cell line, HepG2, were treated up to 96 h with apabetalone or other BET inhibitors (BETi). Gene expression was analyzed by microarray or RT-PCR. Human aortic endothelial cells (HAEC) were pretreated with apabetalone for 1 h followed by TNFα stimulation for another 1h. Chromatin occupancy of the BET protein BRD4 was examined by ChIP-seq.

Results: In RPTEC, 5µM apabetalone downregulated ACE2 mRNA by 50%. Apabetalone dose dependently reduced ACE2 gene expression in HepG2 or PHH from 3 independent donors by up to 90%. JQ1 is a pan BET inhibitor, whereas MZ1 promotes BET protein degradation. Both JQ1 and MZ1 treatments downregulated ACE2 in liver cells, indicating an on target BETi effect. In HAEC, apabetalone abolished BRD4 occupancy at an enhancer in proximity to the ACE2 gene.

Conclusions: Apabetalone reduces ACE2 gene expression in multiple human cell types. ACE2 expression may be regulated by adjacent BRD4 enhancer occupancy. The impact of apabetalone on SARS-CoV-2 life cycle is under investigation. The results will provide mechanistic support for potential COVID-19 clinical trials.