Quantitative Proteomics Reveals the Role of Lysine Lactylation in Lenalidomide-Resistance in Multiple Myeloma Cells

Multiple myeloma (MM) is a hematologic malignancy characterized by abnormal plasma cell proliferation, with lenalidomide emerging as a primary treatment. However, prolonged use often leads to drug resistance, underscoring the need to understand the resistance mechanisms. Protein post-translational modifications (PTMs) play crucial roles in disease development, including chemoresistance. Here, we investigate the involvement of new types of PTMs, focusing on lysine lactylation (Kla), in lenalidomide-resistance. Glycolysis-driven elevation of Kla levels was observed in lenalidomide-resistant MM cells, and the subsequent inhibition of glycolytic activity significantly reversed the lenalidomide-resistance phenotype. Through quantitative proteome, lactylome, and acetylome analyses, we identified 7493 proteins, 1241 Kla sites, and 9313 lysine acetylation (Kac) sites, thereby revealing differential protein expression and PTM profiles in lenalidomide-resistant cells. Proteomic analysis revealed that a series of chemoresistance-related proteins were upregulated, and a number of Cullin-RING Ligase 4-Cereblon (CRL4^CRBN) regulatory factors were downregulated. Lactylome analysis revealed that numerous chemoresistance-related proteins exhibited increased Kla levels in lenalidomide-resistant MM cells, suggesting that Kla played an important role in the development of lenalidomide-resistance in LenR MM cells. Notably, histone H4K8la was associated with upregulation of chemoresistance-related genes cyclin-dependent kinase 6 (CDK6) and enoyl-CoA hydratase (ECHS1). Our findings shed light on the epigenetic mechanisms underlying lenalidomide-resistance in MM, offering insights for overcoming chemoresistance.