Monastrol-Inspired Library Screen Yields Two New Drug Candidates Against Colorectal Cancer

Colorectal cancer remains one of the most common and deadly malignancies worldwide, and the limited effectiveness of existing therapies for advanced disease continues to drive an urgent search for new chemical weapons. A team of Spanish researchers has now reported a computational and experimental pipeline that sifted through an enormous combinatorial library of 1.6 million compounds to uncover two new drug candidates capable of disrupting the machinery that colorectal tumor cells use to grow and spread. Their findings, published in the open-access journal Cancer Cell International, describe how a pharmacophore model derived from the well-known antimitotic compound monastrol guided a high-throughput virtual screen that ultimately produced two molecules, designated Z118298144 and Z17544625, with measurable anticancer activity in colorectal cancer cell cultures.

Monastrol has long occupied a special place in the cancer pharmacology literature. Originally identified as a small molecule that binds kinesin Eg5, a motor protein essential for proper spindle formation during cell division, it has served as a prototypical antimitotic agent in numerous studies of cancer cell biology. But the compound’s story did not end there. More recent work revealed that monastrol also interacts with fascin, an actin-bundling protein that has emerged as a key player in tumor aggressiveness and metastatic behavior. By engaging fascin, monastrol disrupts the dynamics of microtubules and the bundling of actin filaments, ultimately impairing the ability of cancer cells to migrate. This dual activity made monastrol an attractive starting point for medicinal chemistry: a molecule whose binding features could be reverse-engineered to find improved analogs targeting the metastatic machinery of tumors.

The research team, led by Alejandro Rodríguez-Martínez and Horacio Pérez-Sánchez of UCAM Universidad Católica de Murcia, together with collaborators at the University of Granada, Fundación MEDINA, and the Instituto Murciano de Investigación Biosanitaria, set out to exploit that insight systematically. Their strategy centered on a ligand-based pharmacophore model, a simplified three-dimensional representation of the spatial and chemical features that a molecule must display to bind fascin effectively. Such models capture the essential hydrogen-bond donors and acceptors, hydrophobic regions, and aromatic features of a known binder, in this case monastrol, and allow computational filters to be applied across vast chemical databases. Rather than testing compounds one by one at the bench, the researchers let the pharmacophore do the first round of triage on a high-throughput screening library containing 1.6 million commercially available, combinatorial compounds.

The virtual screening workflow was not a single calculation but a cascade of increasingly stringent filters. After the initial pharmacophore search identified molecules whose geometry and chemical functionality matched the monastrol-derived pattern, the top-ranking candidates were subjected to further physicochemical characterization, a step designed to weed out compounds with unfavorable drug-like properties before any laboratory resources were committed. The authors describe this as an optimized pipeline that integrates computational prediction with in vitro validation, a design philosophy that reflects the realities of modern drug discovery: computational methods can reduce the search space by orders of magnitude, but only experimental confirmation can establish that a predicted binder actually engages its target in solution and inside a living cell.

Two compounds emerged from this gauntlet with particularly compelling profiles. Z118298144 and Z17544625 both demonstrated strong binding to fascin in physicochemical assays, and both inhibited the actin-bundling activity that gives fascin its pro-metastatic function. The experimental validation relied in part on differential scanning fluorimetry, a technique that monitors the thermal stability of a protein in the presence and absence of a ligand; a genuine binder typically shifts the protein’s melting temperature, providing a quantitative and reproducible readout of binding. Complementary high-content imaging assays assessed fascin-dependent F-actin bundling directly, confirming that the binding events observed in the thermal shift experiments translated into functional inhibition of the protein’s biological activity.

The critical question, of course, was whether this molecular-level activity would matter inside an actual cancer cell. To answer it, the team turned to cellular experiments using colorectal cancer cell lines. Both compounds reduced the proliferation of CRC cells and impaired their migration at micromolar concentrations, a potency range that is respectable for early-stage chemical starting points and leaves room for optimization. Migration assays are particularly relevant in this context, because fascin’s role in tumor biology centers on the assembly of actin-based protrusions such as filopodia, which cancer cells use to invade surrounding tissue and metastasize. A compound that blocks fascin-mediated actin bundling is, in effect, targeting the physical apparatus of metastasis rather than simply killing dividing cells, and the researchers’ demonstration that both molecules hamper CRC cell migration suggests that this mechanism is genuinely engaged in the cellular context.

Structural detail on how the two hit compounds interact with fascin was obtained through molecular dynamics simulations, which followed the behavior of the fascin-ligand complexes over time after docking into the protein’s known binding regions. Fascin presents multiple binding pockets, including two actin-binding sites and a tubulin-interacting site, and the simulations tracked the minimum distances between each compound and key residues across these sites, along with hydrogen-bond networks that stabilize the bound poses. This atomistic layer of analysis supports the pharmacophore-based identification strategy and provides starting points for future structure-guided optimization, since the residues contacted by Z118298144 and Z17544625 can now be targeted deliberately in analog design.

Importantly, the researchers also addressed safety signals early in the characterization process. Supplementary dose-response experiments assessed the cytotoxicity of Z118298144 and monastrol in two non-cancerous human cell lines using a resazurin-based metabolic viability assay, providing an initial read on whether the new compound spares healthy cells at the concentrations that affect tumor cells. Such counterscreens are a standard but often underappreciated part of early drug discovery, and their inclusion in this study reflects a pipeline designed not merely to find binders but to find binders worth pursuing as therapeutic leads.

Beyond the two specific compounds, the study’s broader contribution is the validated workflow itself. The authors report that the protocol has been successfully adapted for application to additional cancer-related targets, expanding its potential utility across drug discovery programs. In an era when combinatorial chemistry has made billions of compounds synthetically accessible but experimental screening capacity remains finite, hybrid approaches that combine pharmacophore modeling, virtual screening, physicochemical filtering, and targeted in vitro validation offer a practical route through the haystack. The funding for the work came from a consortium of Spanish and European sources, including the Scientific Foundation of the Spanish Association against Cancer, the Andalusian Regional Government, the European Union Horizon 2020 REVERT project, and the Instituto de Salud Carlos III, with computational resources provided by the Plataforma Andaluza de Bioinformática, the Barcelona Supercomputing Center, and the NLHPC supercomputing infrastructure.

For patients with colorectal cancer, the road from a micromolar cell-culture hit to an approved medicine is long and uncertain, and neither Z118298144 nor Z17544625 is being presented as a ready therapy. What the study delivers instead is proof of concept: that a monastrol-derived pharmacophore can be used to mine a 1.6-million-compound library efficiently, that the resulting hits genuinely bind fascin and block its actin-bundling function, and that this molecular interference translates into reduced proliferation and impaired migration in colorectal cancer cells. Fascin has been implicated in the aggressiveness of multiple tumor types, and validated chemical inhibitors of the protein have been scarce. By pairing computational triage with rigorous biophysical and cellular validation, the Spanish team has added two new chemical starting points to a thin field and demonstrated a reusable pipeline that other laboratories can now apply to fascin and to further cancer targets. The next steps, medicinal chemists will note, involve improving potency, selectivity, and pharmacokinetic properties of the two hits, work that the published structural and biophysical data are well positioned to support.

Subject of Research: Identification of monastrol-derived fascin inhibitors as potential colorectal cancer therapeutics through virtual screening and experimental validation.

Article Title: Characterizing compounds targeting colorectal cancer derived from monastrol using high-through screening of an extensive combinatorial library

Article References: Characterizing compounds targeting colorectal cancer derived from monastrol using high-through screening of an extensive combinatorial library. (n.d.). https://doi.org/10.1186/s12935-026-04467-0

Image Credits: AI Generated

DOI: 10.1186/s12935-026-04467-0

Keywords: colorectal cancer, monastrol, fascin, virtual screening, drug discovery, actin bundling, high-throughput screening, pharmacophore model, molecular dynamics, cellular assays, kinesin Eg5, anticancer compounds