(P21-008-25) The Influence of TP53 Expression on K562 Cell Lipid Metabolism and Differentiation

Objectives: Activation of TP53 signaling during ribosome biogenesis is an essential part of erythroid development, whereas the pathologic activation of TP53 in ribosomopathies such as Diamond-Blackfan anemia (DBA) and del(5q) myelodysplastic syndrome (MDS) prevents the normal expansion of erythroid precursors. TP53 can also be linked to the pathogenesis of DBA and MDS via ferroptosis, a form of iron-mediated cell death propagated by excess PUFA-containing oxidizable phospholipids and loss of lipid peroxide repair capacity. The primary objective of this work was to establish how overexpression and mutation of the TP53 gene influences lipid composition, erythroid differentiation, and ferroptosis sensitivity in K562 cells, an in vitro model for studying erythropoiesis.

Methods: Employing a reverse genetics approach, we generated four isogenic cell lines that either lacked TP53 expression, expressed wild-type (WT) TP53, or expressed one of the two most common TP53 mutation types, R175H and R282W. We then utilized non-targeted lipidomics to quantify and identify changes in specific lipid species that occur with induction of WT and mutant TP53. We also analyzed differences in gene expression, ferroptosis sensitivity, and hemoglobinization by qPCR, CCK-8, and o-dianisidine staining, respectively.

Results: Intriguingly, the abundance of 337 distinct lipid species was impacted by induction of WT TP53 expression alone compared to TP53 null K562 cells. Yet, only 18 lipid compounds were differentially impacted between cells expressing WT TP53 and either of the mutant TP53 genes tested. Similarly, while the TP53 null K562 cells displayed modest sensitivity to ferroptosis, cells expressing both WT and mutant TP53 genes were remarkably resistant to ferroptosis. Whereas differentiation and hemoglobinization were not significantly impacted by TP53 status in this cell line.

Conclusions: Induction of TP53 expression in K562 cells significantly alters intracellular lipid composition, but does not have a profound impact on ferroptosis sensitivity or differentiation. However, as changes in lipid metabolism are critical for terminal erythropoiesis, this work provides novel insights into the role of TP53 in this process.

Funding Sources: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Hematology Centers Program
G-RISE at Oklahoma State University