Discovery of new Hsp90-Cdc37 protein-protein interaction inhibitors: in silico screening and optimization of
Jaka Dernovšek1, Nina Gradišek1, Živa Zajec1
1Faculty of Pharmacy, University of Ljubljana Aškerčeva cesta 7 1000 Ljubljana Slovenia tihomir.tomasic@ffa.uni-lj.si.
Abstract:
The interaction between heat shock protein 90 (Hsp90) and Hsp90 co-chaperone cell-division cycle 37 (Cdc37) is crucial for the folding and maturation of several oncogenic proteins, particularly protein kinases. This makes the inhibition of this protein-protein interaction (PPI) an interesting target for developing new anticancer compounds. However, due to the large interaction surface, developing PPI inhibitors is challenging. In this work, we describe the discovery of new Hsp90-Cdc37 PPI inhibitors using a ligand-based virtual screening approach. Initial hit compounds showed Hsp90 binding, resulting in anticancer activity in the MCF-7 breast cancer cell line. To optimize their antiproliferative effect, 35 analogs were prepared. Binding affinity for Hsp90 was determined for the most promising compounds, 8c (K d = 70.8 μM) and 13g (K d = 73.3 μM), both of which interfered with the binding of Cdc37 to Hsp90. This resulted in anticancer activity against Ewing sarcoma (SK-N-MC), breast cancer (MCF-7), and leukemia (THP-1) cell lines in vitro. Furthermore, compounds 8c and 13g demonstrated the ability to induce apoptosis in the Ewing sarcoma cell line and caused a decrease in the levels of several known Hsp90 client proteins in MCF-7 cells, all without inducing the heat shock response.
Insights
Researchers discovered new compounds that inhibit the interaction between heat shock protein 90 (Hsp90) and its co-chaperone Cdc37. These inhibitors show anticancer activity against various cancer cell lines by disrupting Hsp90 function.
Area of Science:
- Oncology
- Molecular Biology
- Drug Discovery
Background:
- The Hsp90-Cdc37 protein-protein interaction (PPI) is vital for stabilizing oncogenic proteins, making it a promising anticancer target.
- Developing inhibitors for large PPI surfaces like Hsp90-Cdc37 presents significant challenges.
Purpose of the Study:
- To discover and optimize novel inhibitors targeting the Hsp90-Cdc37 PPI.
- To evaluate the anticancer efficacy and mechanism of action of identified inhibitors.
Main Methods:
- Ligand-based virtual screening was employed to identify initial hit compounds.
- Analog synthesis and optimization were performed to enhance antiproliferative effects.
- Binding affinity assays, in vitro anticancer activity assays, apoptosis induction studies, and Western blotting were utilized.
Main Results:
- Initial hits demonstrated Hsp90 binding and anticancer activity in MCF-7 cells.
- Optimized compounds 8c and 13g exhibited significant binding affinity for Hsp90 and interfered with Cdc37 binding.
- Compounds 8c and 13g showed in vitro anticancer activity against Ewing sarcoma, breast cancer, and leukemia cell lines.
- These compounds induced apoptosis in Ewing sarcoma cells and reduced Hsp90 client protein levels in breast cancer cells without triggering the heat shock response.
Conclusions:
- Novel Hsp90-Cdc37 PPI inhibitors were successfully developed using a virtual screening approach.
- The identified compounds exhibit potent anticancer activity through Hsp90 client protein destabilization and apoptosis induction.
- These inhibitors represent a promising new class of anticancer agents targeting a critical oncogenic pathway.
