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Structure-Guided SOCS3 Peptidomimetics: Design and Functional Characterization
Alessia Cugudda1, Sara La Manna1, Candida Bucciero2
1Department of Pharmacy, University of Naples Federico II, Naples 80131, Italy.
Abstract:
Suppressor of Cytokine Signaling 3 (SOCS3) is a pivotal negative regulator of the JAK/STAT pathway, and its loss or silencing is frequently associated with hyperactivated STAT3 signaling in aggressive cancers, including Triple-Negative Breast Cancer (TNBC). In this study, we present the rational design, biophysical characterization, and cellular evaluation of novel SOCS3-derived peptidomimetics that incorporate a hitherto unexploited structural determinant of the SOCS3/JAK2/Gp130 interface: the BC loop. The synthesis of individual and chimeric peptides was guided by structural analysis of the ternary complex, which combined the KIR/ESS regions with a stabilized BC loop. The results of the study revealed that the chimeric construct, KIRESS BC loop-chim, exhibited markedly improved affinity for JAK2 (K D ∼ 10 μM) in comparison to the affinity of the isolated regions. This was determined by means of MicroScale Thermophoresis (MST). Circular dichroism (CD) and fluorescence spectroscopy demonstrated that turn-inducing motifs stabilize native-like conformations, correlating with enhanced serum stability. To preliminarily evaluate potential cellular effects, we assessed their serum stabilities and their cytotoxicity in MDA-MB-231 and MDA-MB-468 cells once conjugated to a small Cell-Penetreting Peptide (CPP). In both cases, the good biocompatibility of the designed mimetics appeared promising for evaluating signaling-dependent effects. These findings validate a multiregion, structure-guided design strategy and identify an improved SOCS3 proteomimetic scaffold with potential for targeting dysregulated JAK/STAT signaling in cancer.
Insights
Researchers designed novel SOCS3-derived peptidomimetics to target the JAK/STAT pathway in aggressive cancers like Triple-Negative Breast Cancer (TNBC). A chimeric construct showed improved JAK2 binding and stability, offering a promising scaffold for cancer therapy.
Area of Science:
- Biochemistry and Molecular Biology
- Cancer Therapeutics
- Structural Biology
Background:
- Suppressor of Cytokine Signaling 3 (SOCS3) normally inhibits the JAK/STAT pathway.
- Loss of SOCS3 is linked to hyperactivated STAT3 signaling in aggressive cancers, including Triple-Negative Breast Cancer (TNBC).
- Targeting the JAK/STAT pathway is a key strategy in cancer treatment.
Purpose of the Study:
- To design and characterize novel SOCS3-derived peptidomimetics.
- To investigate the potential of these mimetics in targeting dysregulated JAK/STAT signaling in cancer.
- To explore the role of the SOCS3 BC loop in JAK2 interaction.
Main Methods:
- Rational design of peptidomimetics based on structural analysis of the SOCS3/JAK2/Gp130 interface.
- Synthesis of individual and chimeric peptides incorporating the BC loop.
- Biophysical characterization using MicroScale Thermophoresis (MST), Circular Dichroism (CD), and fluorescence spectroscopy.
- Cellular evaluation of serum stability and cytotoxicity in TNBC cell lines (MDA-MB-231, MDA-MB-468) when conjugated to a Cell-Penetrating Peptide (CPP).
Main Results:
- A chimeric construct (KIRESS BC loop-chim) demonstrated significantly improved affinity for JAK2 (KD ∼ 10 μM) compared to isolated regions.
- Turn-inducing motifs in the mimetics stabilized native-like conformations, enhancing serum stability.
- Designed peptidomimetics showed good biocompatibility and promising potential for evaluating signaling-dependent effects in cancer cells.
Conclusions:
- A structure-guided, multiregion design strategy successfully yielded improved SOCS3 proteomimetics.
- The stabilized BC loop is a key determinant for enhanced SOCS3/JAK2 interaction.
- These novel peptidomimetics represent a promising scaffold for targeting aberrant JAK/STAT signaling in cancer.
