Pseudo-mutant P53 is a unique phenotype of DNMT3A-mutated pre-leukemia

Amos Tuval, Yardena Brilon, Hadas Azogy, Yoni Moskovitz, Dena Leshkowitz, Tomer M Salame, Mark D Minden, Perry Tal, Varda Rotter, Moshe Oren, Nathali Kaushansky, Liran I Shlush
<span title="2022-02-24">2022</span> <i title="Ferrata Storti Foundation (Haematologica)"> <a target="_blank" rel="noopener" href="" style="color: black;">Haematologica</a> </i> &nbsp;
Pre-leukemic clones carrying DNMT3A mutations have a selective advantage and an inherent chemo-resistance, however the basis for this phenotype has not been fully elucidated. Mutations affecting the gene TP53 occur in pre-leukemic hematopoietic stem/progenitor cells (preL-HSPCs) and lead to chemo-resistance. Many of these mutations cause a conformational change and some of them were shown to enhance self-renewal capacity of preL-HSPCs. Intriguingly, a misfolded P53 was described in AML blasts
more &raquo; ... at do not harbor mutations in TP53, emphasizing the dynamic equilibrium between wild-type (WT) and "pseudo-mutant" conformations of P53. By combining single cell analyses and P53 conformation-specific monoclonal antibodies we studied preL-HSPCs from primary human DNMT3A-mutated AML samples. We found that while leukemic blasts express mainly the WT conformation, in preL-HSPCs the pseudomutant conformation is the dominant. HSPCs from non-leukemic samples expressed both conformations to a similar extent. In a mouse model we found a small subset of HSPCs with a dominant pseudo-mutant P53. This subpopulation was significantly larger among DNMT3AR882H-mutated HSPCs, suggesting that while a pre-leukemic mutation can predispose for P53 misfolding, additional factors are involved as well. Treatment with a short peptide that can shift the dynamic equilibrium favoring the WT conformation of P53, specifically eliminated preL-HSPCs that had dysfunctional canonical P53 pathway activity as reflected by single cell RNA sequencing. Our observations shed light upon a possible targetable P53 dysfunction in human preLHSPCs carrying DNMT3A mutations. This opens new avenues for leukemia prevention.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="">doi:10.3324/haematol.2021.280329</a> <a target="_blank" rel="external noopener" href="">pmid:35199506</a> <a target="_blank" rel="external noopener" href="">fatcat:vzks7i6bjzggpkknb6zqrwyhjy</a> </span>
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