Structural and functional characterization of Acyl-CoA Synthetase Long-Chain Family Member 3 (ACSL3) and its targeted inhibition by gramicidin in multiple myeloma

Relapse and therapeutic resistance remain critical challenges in multiple myeloma (MM). This study investigates the macromolecular drivers of metabolic reprogramming in MM to identify novel therapeutic targets. Through integrated multi-omics profiling, we identified significant dysregulation in long-chain fatty acid metabolism, pinpointing the protein Acyl-CoA Synthetase Long-Chain Family Member 3 (ACSL3) as a central pathogenic factor. Clinical validation revealed that ACSL3 expression is significantly upregulated in MM cell lines and patient bone marrow compared to healthy controls, correlating with disease recurrence. Furthermore, in vitro and in vivo ACSL3 loss- and gain-of-function experiments established ACSL3 as a causal driver of MM cell survival. To elucidate the structural basis for targeting this macromolecule, we performed molecular docking simulations and surface plasmon resonance (SPR) assays. These integrated studies identified gramicidin as a novel direct inhibitor, revealing high-affinity binding interactions within the ACSL3 active site. Functional experimental validation demonstrated that targeting ACSL3 with gramicidin significantly suppressed MM growth in vitro and in vivo, induced apoptosis, and disrupted lipid metabolism. The observed effects were specifically rescued by ACSL3 overexpression. Additionally, we established a robust 8-metabolite signature that accurately predicts MM recurrence, outperforming standard clinical staging. This study characterizes the functional role of the biological macromolecule ACSL3 in MM pathogenesis and provides structural, biological, and preclinical evidence for its inhibition by gramicidin as a potential therapeutic strategy.