Allosteric Covalent Inhibitors of the STAT3 Transcription Factor from Virtual Screening

Area of Science:

• Oncology
• Molecular Biology
• Drug Discovery

Background:

• Signal transducer and activator of transcription (STAT) proteins are crucial signaling hubs in cellular processes.
• STAT3 is a significant oncotarget, with ongoing clinical trials for cancer therapy.
• Existing small-molecule inhibitors primarily target the SH2 domain of STAT3.

Purpose of the Study:

• To identify novel small-molecule inhibitors targeting a less-explored binding site on STAT3.
• To develop chemical biology tools for future research on STAT3 signaling.
• To lay the groundwork for advanced lead optimization of STAT3 inhibitors.

Main Methods:

• Utilized virtual screening to identify potential inhibitors.
• Focused on a binding site at the junction of STAT3's coiled-coil and DNA-binding domains.
• Employed structure-guided hit expansion and optimization.

Main Results:

• Discovered several lead-like covalent inhibitors against the targeted STAT3 site.
• Optimized a lead compound into a low micromolar inhibitor.
• Validated a novel binding site for small-molecule targeting.

Conclusions:

• A novel, sparsely studied binding site on STAT3 was successfully targeted with covalent inhibitors.
• The developed inhibitor can serve as a valuable chemical biology tool.
• This work provides a foundation for developing new STAT3-targeted cancer therapies.