Proteomic Comparison of Acute Myeloid Leukemia Cells and Normal CD34+ Bone Marrow Cells: Studies of Leukemia Cell Differentiation and Regulation of Iron Metabolism/Ferroptosis.

Abstract

Acute myeloid leukemia (AML) is an aggressive bone marrow malignancy that can be cured only by intensive chemotherapy possibly combined with allogeneic stem cell transplantation. We compared the pretreatment proteomic profiles of AML cells derived from 50 patients at the time of first diagnosis with normal CD34⁺ bone marrow cells. A comparison based on all AML and CD34⁺ normal cell populations identified 121 differentially abundant proteins that showed at least 2-fold differences, and these proteins included several markers of neutrophil differentiation (e.g., TLR2, the integrins ITGM and ITGX, and downstream mediators including RHO GTPase, S100A8, S100A9, S100A22). However, the expression of these 121 proteins varied between patients, and a subset of 28 patients was characterized by increased long-term AML-free survival, signs of myeloid AML cell differentiation, and favorable genetic abnormalities. These two main patient subsets (28 with differentiation versus 22 with fewer signs of differentiation) also differed with regard to the phosphorylation of 16 differentially abundant proteins. Furthermore, we also classified our patients based on their expression of 16 proteins involved in the regulation of iron metabolism/ferroptosis and showing differential expression when comparing AML cells and normal CD34+ cells. Among the 22 patients with less favorable prognosis, we could then identify a genetically heterogeneous subset characterized by adverse prognosis (i.e., death from primary resistance/relapse) and an iron metabolism/ferroptosis protein profile showing similarities with normal CD34⁺ cells. We conclude that proteomic profiles differ between AML and normal CD34⁺ cells; especially, proteomic differences reflecting differentiation and regulation of iron metabolism/ferroptosis are associated with risk of relapse after intensive conventional therapy.