Details

Autor(en) / Beteiligte

• Casellas Román, Heidi L

Titel

Characterizing Sensitivity to Hypomethylating Agents in Myelodysplasia with DNMT3A Mutations

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2020

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• Myelodysplastic syndromes (MDS) are clonal disorders of blood stem cells characterized by impaired differentiation (dysplasia) and peripheral blood cytopenia, with high risk of progression to overt leukemia. It is common in the elderly, which limits treatment options. DNA hypomethylating agents (HMAs) are a mainstay in MDS management. However, the molecular mechanism of their efficacy and relationship with mutational profiles are incompletely understood. Studies show high prevalence of mutations in epigenetic modifier genes in MDS. Among these, the DNMT3A gene, which encodes an enzyme catalyzing de novo DNA methylation, is affected in 2-13% of MDS cases, resulting in modest DNA hypomethylation. DNMT3A mutations are associated with shorter overall survival and increased likelihood of leukemic transformation. Interestingly, DNMT3A alterations seem to confer increased sensitivity to HMAs in a number of small clinical trials, although the mechanism is debated. We hypothesize that sensitivity to HMAs in the DNMT3A-mutated context is due to changes in differentiation, rather than direct cytotoxicity. To this end, we characterized the effects of HMA treatment in murine bone marrow cells with different Dnmt3a status. We isolated bone marrow (BM) cells from mice with hematopoietic-specific Dnmt3a deletion (KO), R878H mutation (+/m), or wild-type (WT) controls and treated with increasing concentrations of HMAs azacytidine (Aza) and decitabine (Dac) in vitro to assess cell survival in liquid culture and clonogenic survival and differentiation potential when grown in semisolid media. Our results suggest efficacy of HMAs is not induction of cytotoxicity and shows opposite trends in differentiation between Dnmt3a mutations, suggesting that identification of a subpopulation that may have better response to treatment. These findings are significant because better understanding of the HMA mechanism of action is fundamental for the development of effective and well tolerated treatment approaches for MDS.