Altered expression of metabolic pathways in CLL detected by unlabelled quantitative mass spectrometry analysis

Summary Chronic lymphocytic leukaemia ( CLL ) remains the most common incurable malignancy of B cells in the western world. Patient outcomes are heterogeneous and can be difficult to predict with current prognostic markers. Here, we used a quantitative label‐free proteomic technique to ascertain differences in the B‐cell proteome from healthy donors and CLL patients with either mutated (M‐ CLL ) or unmutated ( UM ‐ CLL ) IGHV to identify new prognostic markers. In peripheral B‐ CLL cells, 349 (22%) proteins were differentially expressed between normal B cells and B‐ CLL cells and 189 (12%) were differentially expressed between M‐ CLL and UM‐ CLL . We also examined the proteome of proliferating CLL cells in the lymph nodes, and identified 76 (~8%) differentially expressed proteins between healthy and CLL lymph nodes. B‐ CLL cells show over‐expression of proteins involved in lipid and cholesterol metabolism. A comprehensive lipidomic analysis highlighted large differences in glycolipids and sphingolipids. A shift was observed from the pro‐apoptotic lipid ceramide towards the anti‐apoptotic/chemoresistant lipid, glucosylceramide, which was more evident in patients with aggressive disease (UM‐ CLL ). This study details a novel quantitative proteomic technique applied for the first time to primary patient samples in CLL and highlights that primary CLL lymphocytes display markers of a metabolic shift towards lipid synthesis and breakdown.