Discovery of Small Molecule CHI3L1 Inhibitors by SPR-Based High-Throughput Screening

ABSTRACT Chitinase-3-like 1 (CHI3L1) is a secreted glycoprotein implicated in carcinogenesis and tumor immune evasion. Elevated CHI3L1 expression is frequently detected in cancer patients, highlighting it as a promising therapeutic target. To overcome the limited availability of small molecule CHI3L1 inhibitors, we established a surface plasmon resonance (SPR)–based high-throughput screening platform and applied it to a focused chemical library of small molecules. Primary screening identified seven hits, with compounds 1-4 and 1-7 validated as CHI3L1 binders (Kd = 10.4 ± 1.0 μM and 7.40 ± 0.78 μM, respectively). Both compounds disrupted the CHI3L1–galectin-3 interaction in AlphaLISA assays and engaged the CHI3L1 binding pocket in docking and molecular dynamics (MD) simulations. Importantly, functional evaluation in a multicellular 3D glioblastoma (GBM) spheroid model demonstrated that compound 1-7 potently reduced spheroid viability and inhibited STAT3 phosphorylation, outperforming both compound 1-4 and the known CHI3L1–STAT3 disruptor hygromycin B (HB). These findings validate SPR as a robust primary screening platform for CHI3L1 and demonstrate that the identified small molecule binders exert functional activity in a physiologically relevant multicellular GBM spheroid model. Competing Interest Statement The authors have declared no competing interest. Data availability The authors confirm that all data are available as ESI.† Furthermore, additional data and original files are available from the authors upon request.