In a study published in the journal Molecular Diversity, Kader Sahin of Bahçeşehir University and Bandırma Onyedi Eylül University, Ajda Coker of Marmara University, and Serdar Durdağı of Bahçeşehir University describe a structure-based virtual screening campaign that combed through FDA-approved drugs in search of molecules capable of disrupting the interaction between β-catenin and T-cell factor 4, or Tcf4. This protein–protein interaction is the final, decisive step in Wnt signaling: when β-catenin accumulates in the cell nucleus and binds Tcf4, the complex switches on a battery of genes that drive tumor growth, survival, metastasis, and drug resistance. Block that binding, the logic goes, and the entire oncogenic program collapses.

The catch has always been the shape of the target. The β-catenin/Tcf4 interface sprawls across roughly 4,800 square angstroms, a vast and shallow surface with few of the deep, well-defined pockets that medicinal chemists traditionally exploit. For years, interfaces like this one were written off as undruggable. Yet structural biology has gradually revealed that even sprawling protein–protein interfaces concentrate their binding energy in a handful of so-called hot spots, short stretches of residues that contribute disproportionately to the affinity between the two partners. If a small molecule can be steered into those hot spots, the reasoning goes, it might achieve with a compact drug what would otherwise require a much larger molecule.

That is precisely the strategy the researchers pursued. Rather than screening synthetic chemical libraries filled with untested compounds, they turned to drug repurposing, focusing on medicines that have already passed safety scrutiny and are in clinical use. Repurposing offers a practical shortcut: known pharmacology, established safety profiles, and in many cases existing manufacturing and distribution infrastructure. The team first mapped the critical hot spot residues of β-catenin that engage Tcf4, then used molecular docking to position each candidate drug within the interface, asking which approved molecules could physically occupy and destabilize the contact points that hold the complex together.

The computational pipeline did not stop at docking. To separate plausible binders from artifacts, the researchers subjected the top candidates to physics-based molecular dynamics simulations, watching in atomic detail how each ligand behaved over time when bound to β-catenin. They then calculated binding free energies using the MM/GBSA method, a hybrid approach that combines molecular mechanics energies with implicit solvent models to estimate how strongly a ligand clings to its target. This layered filtering, docking followed by simulation followed by energetic scoring, is designed to weed out compounds that look good in a single static snapshot but fall apart under the thermal motion of a real cellular environment.

Three candidates emerged from the screen with stable binding to the critical hot spot residues of β-catenin, specifically asparagine 430, lysine 435, histidine 470, arginine 474, and lysine 508. They were Leucovorin, also known as folinic acid, a vitamin derivative routinely used to enhance chemotherapy; Carbenicillin, a penicillin-class antibiotic; and Ceforanide, a second-generation cephalosporin. All three are approved, well-characterized medicines, which means that if any of them proves effective against Wnt-driven cancers, the path from bench to bedside could be considerably shorter than for a brand-new chemical entity.

Computational predictions, however convincing, mean little until they are tested in living cells. The team moved their three hits into the laboratory, using HT-29 colorectal cancer cells, a widely studied cell line in which Wnt signaling is aberrantly active. The cells were treated with each compound and assessed for viability and for their ability to form colonies, a measure of long-term proliferative capacity that often correlates with tumorigenic potential. The results were striking: Carbenicillin and Ceforanide reduced cell viability and impaired colony formation, exhibiting superior anti-proliferative activity compared with the other candidates, including Leucovorin.

The convergence between the computational and experimental arms of the study is what gives the findings their weight. The two antibiotics that performed best in cell assays were the same molecules whose simulated binding poses anchored them most securely to the β-catenin hot spots. This consistency suggests that the anti-proliferative effects observed in HT-29 cells may indeed arise from disruption of the β-catenin/Tcf4 interaction, although the researchers are careful to frame the work as a proof of concept rather than a finished therapy. Further studies will be needed to confirm the mechanism directly, to characterize selectivity for cancer cells over healthy tissue, and to establish whether the compounds can achieve therapeutic concentrations in tumors.

Even so, the implications are considerable. Wnt/β-catenin signaling is implicated not only in colorectal cancer but in a broad family of malignancies, including hepatocellular carcinoma and other Wnt-driven tumors, and it also maintains cancer stem cell populations that fuel relapse and metastasis. A validated small-molecule inhibitor of the β-catenin/Tcf4 interaction would be a genuinely new class of anticancer agent, one that attacks the transcriptional engine of the tumor rather than a single downstream symptom. Prior efforts, including peptide mimetics and dedicated small molecules developed in academic labs, have struggled to reach the clinic, which makes the repurposing angle particularly attractive: these are drugs whose toxicity, metabolism, and drug interactions are already documented.

The study also offers a template for tackling other supposedly undruggable targets. By combining hot spot analysis, docking against a library of approved drugs, rigorous molecular dynamics validation, and energetic scoring, and only then moving to cell-based experiments, the researchers demonstrated a workflow that is both computationally disciplined and experimentally grounded. As the authors conclude, their findings provide compelling evidence that targeting the β-catenin/Tcf4 interaction with small molecules is feasible, and that Carbenicillin and Ceforanide may serve as promising repurposed candidates for therapeutic intervention in Wnt-driven malignancies. For patients with colorectal cancer, whose treatment options too often narrow as the disease progresses, the idea that answers might be hiding in plain sight among existing medicines is a hopeful one, and this study shows exactly how such hidden answers can be systematically found.

Subject of Research: Virtual drug repurposing to discover β-catenin/Tcf4 interaction inhibitors for colorectal cancer treatment

Article Title: Hot spot-driven discovery of β-catenin/Tcf4 interaction inhibitors via virtual drug repurposing study and experimental validation in colorectal cancer cells

Article References: Sahin, K., Coker, A., & Durdağı, S. (2026). Hot spot-driven discovery of β-catenin/Tcf4 interaction inhibitors via virtual drug repurposing study and experimental validation in colorectal cancer cells. Molecular Diversity. https://doi.org/10.1007/s11030-026-11720-1

Image Credits: AI Generated

DOI: 10.1007/s11030-026-11720-1

Keywords: β-catenin, Tcf4, Wnt signaling, colorectal cancer, drug repurposing, virtual screening, molecular docking, molecular dynamics, MM/GBSA, Carbenicillin, Ceforanide, protein-protein interaction inhibitors

The research led by Kundil, Suresh, and Chellappan embarks on a journey to explore the druggability of these small peptides as inhibitors of the EED-EZH2 interaction. By assessing how these peptides can effectively disrupt the binding and subsequent functions of the PRC2 complex, the researchers aim to unveil new therapeutic modalities that could lead to enhanced treatment strategies. Achieving a deeper understanding of the mechanisms governing these interactions is crucial for developing effective inhibitors that do not disrupt other essential biological processes.

In their study, the researchers performed a comprehensive analysis of various small peptides, utilizing advanced computational and experimental methods to predict and validate their potential as inhibitors. The methods employed included molecular docking simulations, binding affinity calculations, and biochemical assays that help ascertain the efficacy of each peptide in interfering with the EED-EZH2 binding process. Through these rigorous assessments, the researchers could hone in on promising candidates that exhibited strong inhibitory properties.

Importantly, the characterization of the small peptides involved elucidating their structural and functional attributes, providing insight into how specific amino acid sequences contributed to their ability to mimic or block the native EED-EZH2 interactions. This foundational knowledge is vital for understanding the interplay between peptide design and biological context, guiding future modifications to enhance the efficacy and specificity of the inhibitors developed.

In addition to the structural studies, the research underscores the necessity of exploring the biological implications of inhibiting the EED-EZH2 interaction. Given PRC2’s multifaceted role in regulating gene silencing and maintaining cellular identity, any therapeutic approach targeting this complex must weigh the risks of unintended consequences. The potential benefits of effective EED-EZH2 inhibitors could range from mechanisms that thwart tumor progression to guiding differentiation processes in regenerative medicine.

Notably, the therapeutic implications of this work extend beyond oncology. The modulation of epigenetic regulation opens avenues for addressing a host of diseases characterized by dysregulated gene expression profiles. For example, conditions such as neurodegenerative diseases, where epigenetic alterations contribute to pathogenesis, could benefit from innovative strategies based on the insights gained from targeting the EED-EZH2 interaction.

The study’s findings also contribute to a growing catalog of small molecule and peptide inhibitors designed to target protein-protein interactions, a historically challenging area in drug development. The success of these inhibitors may hinge on the delicate balance between efficacy and selectivity, posing both a challenge and an opportunity for innovative drug design. As pharmaceutical science continues to evolve, the integration of peptide-based inhibitors into the therapeutic landscape could emerge as a game-changing prospect.

In a world increasingly reliant on precision medicine, the ability to selectively modulate specific protein interactions will be paramount. The extensive analyses conducted in assessing small peptides as inhibitors provide a compelling roadmap for future research endeavors. This will push the boundaries of our understanding of protein functions and interactions, potentially leading to the emergence of advanced therapeutic agents tailored to individual patient profiles.

With the advent of high-throughput screening technologies and sophisticated computational capabilities, the pace of discovery in the realm of protein-protein interactions is accelerating. As researchers build on the findings reported by Kundil and colleagues, the potential for translating these basic scientific insights into clinical applications grows exponentially. Indeed, the goal of realizing a new generation of drugs that can selectively target pathological processes at the molecular level is inching closer to reality.

In conclusion, the research highlighting the druggability of small peptides as inhibitors of the EED-EZH2 interaction sheds light on a critical component of epigenetic regulation. As the scientific community continues to decipher the complexities of protein interactions, the promise of these small peptides as therapeutic agents signifies a pivotal advancement in drug discovery. Future investigations will undoubtedly refine our understanding and harness the therapeutic potential of targeting such critical pathways.

By delving into the intricate world of protein-protein interactions, the research team has laid a significant foundation for developing novel inhibitors that could affect a wide array of diseases linked to the dysfunction of epigenetic mechanisms. As we anticipate the follow-up studies and clinical validation, one thing is certain: the journey to unraveling the complexities of molecular interactions in health and disease is just beginning. The era of targeting the epigenetic landscape with precision is on the horizon, and the implications for human health could be profound.

With this exciting research at our fingertips, the next steps will be crucial to bring these findings from the laboratory into therapeutic contexts, pushing the field of epigenetic drug development into new territories.

Subject of Research: Small peptides as protein–protein interaction inhibitors targeting EED-EZH2 binding within the Polycomb Repressive Complex 2 (PRC2)

Article Title: Druggability assessments of small peptides as protein–protein interaction inhibitors targeting EED-EZH2 binding within the Polycomb Repressive Complex 2 (PRC2), an epigenetic regulator.

Article References:

Kundil, V.T., Suresh, S.C., Chellappan, S. et al. Druggability assessments of small peptides as protein–protein interaction inhibitors targeting EED-EZH2 binding within the Polycomb Repressive Complex 2 (PRC2), an epigenetic regulator. Mol Divers (2025). https://doi.org/10.1007/s11030-025-11321-4

Image Credits: AI Generated

DOI: 10.1007/s11030-025-11321-4

Keywords: EED-EZH2 interaction, small peptides, PRC2, protein-protein interaction, druggability assessments, epigenetics, therapeutic interventions, cancer research.