Virtual High Throughput Screening to identify novel activin antagonists.
J Med Chem. 2015 Jun 22;
Authors: Zhu J, Mishra RK, Schiltz G, Makanji Y, Scheidt KA, Mazar A, Woodruff TK
Activin belongs to the TGFβ superfamily, which is associated with several disease conditions including cancer-related cachexia, preterm labor with delivery, and osteoporosis. Targeting activin and its related signaling pathways holds promise as a therapeutic approach to these diseases. A small molecule ligand binding groove was identified in the interface between the two activin βA subunits and was used for a virtual high throughput in silico screening of the ZINC database to identify hits. 39 Compounds without significant toxicity were tested in two well-established activin assays: FSHβ transcription and HepG2 cell apoptosis. This screening workflow resulted in two lead compounds, NUCC-474 and NUCC-555. These potential activin antagonists were then shown to inhibit activin A-mediated cell proliferation in ex vivo ovary cultures. In vivo testing showed that our most potent compound (NUCC-555) caused a dose-dependent decrease in FSH levels in ovariectomized mice. The Blitz competition binding assay confirmed target binding of NUCC-555 to the activin A:ActRII that disrupts the Activin A:ActRII complex binding with ALK4-ECD-Fc in a dose dependent manner. The NUCC-555 also specifically binds to activin A compared with other TGFβ superfamily member myostatin (GDF8). These data demonstrate a new in silico-based strategy for identifying small molecule activin antagonists. Our approach is the first to identify a first-in-class small molecule antagonist of activin binding to ALK4, which opens a completely new approach to inhibiting the activity of TGF-beta receptor superfamily members. Also the lead compound can serve as a starting point for lead optimization toward the goal of a compound that may be effective in activin-mediated diseases.
PMID: 26098096 [PubMed - as supplied by publisher]