Abstract
The glucocorticoid (GC) resistance onset in pediatric T-cell acute lymphoblastic leukemia (T-ALL) patients remains one of the biggest challenges in current cancer treatment. The mechanisms driving this resistance are still not fully understood, making it difficult to predict patient outcomes and to develop effective therapies. Our study uncovered critical insights into the biological processes underlying GC resistance, offering potential breakthroughs for future treatments. Building on our previous research on lymphocyte cell-specific protein-tyrosine kinase (LCK) hyperactivation in GC-resistant T-ALL patients, we have now delved deeper into the LCK downstream nuclear factor of activated T cells (NFAT) transcription factor family's contribution to GC resistance. We discovered that, even at the time of diagnosis, GC resistant T-ALL patients exhibit an intrinsic low glucocorticoid receptor (GR) activity coupled with high NFATc1 and NFATc2 activity. This dysregulation creates a roadblock to effective GC therapy. Indeed, in the absence of either NFATc1 or NFATc2, the normal transcriptional activity of GR is restored, re-sensitizing leukemia cells to dexamethasone treatment both in vitro and in vivo. This suggests that NFATc1 and NFATc2 are central to driving GC resistance, as they directly regulate crucial pathways like cholesterol biosynthesis and WNT/β-catenin signaling. The identification of NFAT transcription factors as key players in leukemia therapy resistance offers a promising target for future therapeutic strategies, potentially transforming the way we approach treatment for these challenging conditions or autoimmune disorders where glucocorticoids are a cornerstone of treatment.