Mechanistic investigation of keratinocyte injury induced by the small-molecule PD-L1 inhibitor BMS-1 via network toxicology, molecular dynamics simulation and cellular assays

Abstract

Abstract Background Programmed cell death ligand 1 (PD-L1) inhibitors are important agents for lung cancer immunotherapy. However, they frequently cause cutaneous toxicity in clinical practice, which compromises therapeutic compliance. Current studies mostly focus on immune cells, while the direct role of keratinocytes remains unclear. In this study, we used the PD-L1 small-molecule inhibitor BMS-1 as a tool compound to investigate its potential targets and non-immune mechanisms of keratinocyte toxicity by integrating network toxicology, molecular dynamics simulations, and in vitro experiments. Methods In the present study, potential targets responsible for cutaneous toxicity induced by PD-L1 inhibitors were predicted using public databases. Gene ontology and pathway enrichment analyses were performed via the DAVID database. Key targets were identified from the established protein-protein interaction (PPI) network and further validated in conjunction with differentially expressed genes derived from the GEO database. The binding interactions between PD-L1 inhibitors and core targets were verified by molecular docking, molecular dynamics simulation, and in vitro cellular experiments. Results A total of 246 potential targets associated with cutaneous toxicity induced by the PD-L1 inhibitor BMS-1 were identified via network toxicology. GO and KEGG analyses revealed that these targets were mainly enriched in pathways related to inflammation, proliferation and apoptosis. Following screening with multiple algorithms and validation using GEO datasets, ALB, EGFR and MMP9 were recognized as core targets. Molecular docking demonstrated that the docking scores of BMS-1 to all three targets were below − 5 kcal·mol⁻¹, and 100 ns molecular dynamics simulations confirmed stable conformations of the complexes. MM/PBSA theoretical binding free energy calculations further revealed an affinity ranking of MMP9 > ALB > EGFR, with van der Waals interactions serving as the dominant driving force and polar solvation energy consistently contributing a desolvation penalty. Interaction fingerprint analysis indicated that van der Waals packing and π‑interactions of hydrophobic and aromatic residues were central to complex stabilization, with MMP9 exhibiting the most favorable binding potential through its strong hydrophobic network.Cellular assays indicated that BMS-1 suppressed HaCaT cell proliferation, elevated mRNA expression of IL‑1β and TNF‑α, and regulated target gene expression: downregulating ALB while upregulating EGFR and MMP9. Conclusions The small-molecule PD-L1 inhibitor BMS-1 induces HaCaT cell injury by suppressing ALB and promoting EGFR and MMP9 expression. These results provide a mechanistic hypothesis for BMS-1 related keratinocyte damage, but caution should be exercised when extrapolating to clinically approved PD-L1 antibodies, as their pharmacokinetic and immunomodulatory profiles differ substantially. Further studies are warranted to validate the relevance of these targets in clinical cutaneous adverse reactions.