Signal Transducer and Activator of Transcription 3 (STAT3) is a key transcription factor involved in regulating a wide array of cellular processes, including proliferation, survival and immune response. Dysregulated STAT3 activation has been implicated in several diseases, including aggressive cancers, autoimmune disorders, and inflammatory conditions. As a result, STAT3 has become a high-priority target for therapeutic intervention.
The SH2 domain of STAT3 plays a critical role in dimerization and signal transduction through specific phospho-Tyr interactions. This region has been intensely studied as a binding site for inhibitors, peptidomimetics and PROTACs (Proteolysis Targeting Chimeras).1
KINETICfinder® Unlocks Insights into STAT3 Inhibitionn
Using the KINETICfinder® platform, we investigated the binding kinetics of Ac-GpYLPQTV-NH₂, a peptide derived from the gp130 receptor. Known for its strong affinity to STAT3, the peptide demonstrated a dissociation constant (Kd) of 150 nM in Fluorescent Polarization assays and 330 nM in SPR assays, serving as a model ligand for SH2-targeting drug discovery.2, 3
Our kinetic analysis reinforced these findings, showing a robust interaction between STAT3 and Ac-GpYLPQTV-NH₂, with a dissociation constant (Kd) of 116 nM, an a relatively fast association and dissociation rates.
| Compound | Kd (nM) | On‑rate (M‑1s‑1) |
Off‑rate (s‑1) |
Residence time (min) |
|---|---|---|---|---|
| Ac‑GpYLPQTV‑NH2 | 116 ± 11 | 6.0×105 ± 8.6×104 | 6.9×10‑2 ± 3.1×10‑3 | 0.24 ± 0.01 |
Figure 1. A) Real‑time binding kinetics of Ac‑GpYLPQTV‑NH2 interacting with STAT3 measured using the KINETICfinder® platform. B) Assay robustness over 4 hours, with signal‑to‑background ratios and Z′ values from 8 control replicates. Table summarizes the affinity and kinetic parameters: association rate (kon), dissociation rate (koff), residence time and equilibrium dissociation constant (Kd), shown as mean ± SD from two independent experiments.
These results underscore the power of the KINETICfinder® platform in advancing STAT3-targeted drug discovery. By providing real-time kinetic data, this platform helps medicinal chemistry teams design and prioritize more effective inhibitors, peptidomimetic antagonists or degraders that target the SH2 domain of STAT3.
References
- Dong J. et al. (2021) Recent Update on Development of Small-Molecule STAT3 Inhibitors for Cancer Therapy: From Phosphorylation Inhibition to Protein Degradation. J Med Chem. 64(13):8884-8915.
- Shahani VM. et al. (2011) Design, synthesis, and in vitro characterization of novel hybrid peptidomimetic inhibitors of STAT3 protein. Bioorg Med Chem. 19(5):1823-38.
- Zhao W. et al. (2010) A cell-permeable Stat3 SH2 domain mimetic inhibits Stat3 activation and induces antitumor cell effects in vitro. J Biol Chem. 2010 Nov 12;285(46):35855-65.