Pseudo-mutant P53 is a unique phenotype of <i>DNMT3A</i>-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
Affiliations
Amos Tuval
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel; Department of Hematology, Meir Medical Center, Kfar Saba
Yardena Brilon
Department of Immunology, Weizmann Institute of Science, Rehovot
Hadas Azogy
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel; Department of Pathology, Sackler Faculty of Medicine, Aviv University, Aviv
Yoni Moskovitz
Department of Immunology, Weizmann Institute of Science, Rehovot
Dena Leshkowitz
Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot
Tomer M. Salame
Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot
Mark D. Minden
Princess Margaret Cancer Centre, University Health Network (UHN), Toronto, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada; Division of Medical Oncology and Hematology, University Health Network, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario
Perry Tal
Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot
Varda Rotter
Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot
Moshe Oren
Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot
Nathali Kaushansky
Department of Immunology, Weizmann Institute of Science, Rehovot
Liran I. Shlush
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel; Division of Hematology, Rambam Health Care Campus, Haifa, Israel; Molecular Hematology Clinic, Maccabi Healthcare Services, Aviv
Pre-leukemic clones carrying DNMT3A mutations have a selective advantage and an inherent chemoresistance, 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-HSPC) and lead to chemoresistance. Many of these mutations cause a conformational change and some of them were shown to enhance self-renewal capacity of preL-HSPC. Intriguingly, a misfolded P53 was described in AML blasts that 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-HSPC from primary human DNMT3A-mutated AML samples. We found that while leukemic blasts express mainly the WT conformation, in preL-HSPC the pseudo-mutant conformation is the dominant. HSPC from non-leukemic samples expressed both conformations to a similar extent. In a mouse model we found a small subset of HSPC with a dominant pseudo-mutant P53. This subpopulation was significantly larger among DNMT3AR882H-mutated HSPC, 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-HSPC 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 preL-HSPC carrying DNMT3A mutations. This opens new avenues for leukemia prevention.