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|Ref Type||Journal Article|
|Authors||Lu R, Wang J, Ren Z, Yin J, Wang Y, Cai L, Wang GG|
|Title||A Model System for Studying the DNMT3A Hotspot Mutation (DNMT3AR882) Demonstrates a Causal Relationship between Its Dominant-Negative Effect and Leukemogenesis.|
|Date||2019 Jul 15|
|Abstract Text||Mutation of DNA methyltransferase 3A at arginine 882 (DNMT3AR882mut) is prevalent in hematologic cancers and disorders. Recently, DNMT3AR882mut has been shown to have hypomorphic, dominant-negative, and/or gain-of-function effects on DNA methylation under different biological contexts. However, the causal role for such a multifaceted effect of DNMT3AR882mut in leukemogenesis remains undetermined. Here, we report TF-1 leukemia cells as a robust system useful for modeling the DNMT3AR882mut-dependent transformation and for dissecting the cause-effect relationship between multifaceted activities of DNMT3AR882mut and leukemic transformation. Ectopic expression of DNMT3AR882mut and not wild-type DNMT3A promoted TF-1 cell transformation characterized by cytokine-independent growth, and induces CpG hypomethylation predominantly at enhancers. This effect was dose dependent, acted synergistically with the isocitrate dehydrogenase 1 (IDH1) mutation, and resembled what was seen in human leukemia patients carrying DNMT3AR882mut. The transformation- and hypomethylation-inducing capacities of DNMT3AR882mut relied on a motif involved in heterodimerization, whereas its various chromatin-binding domains were dispensable. Mutation of the heterodimerization motif that interferes with DNMT3AR882mut binding to endogenous wild-type DNMT proteins partially reversed the CpG hypomethylation phenotype caused by DNMT3AR882mut, thus supporting a dominant-negative mechanism in cells. In mice, bromodomain inhibition repressed gene-activation events downstream of DNMT3AR882mut-induced CpG hypomethylation, thereby suppressing leukemogenesis mediated by DNMT3AR882mut. Collectively, this study reports a model system useful for studying DNMT3AR882mut, shows a requirement of the dominant-negative effect by DNMT3AR882mut for leukemogenesis, and describes an attractive strategy for the treatment of leukemias carrying DNMT3AR882mut. SIGNIFICANCE: These findings highlight a model system to study the functional impact of a hotspot mutation of DNMT3A at R882 in leukemia.|
|Molecular Profile||Treatment Approach|
|Gene Name||Source||Synonyms||Protein Domains||Gene Description||Gene Role|
|Therapy Name||Drugs||Efficacy Evidence||Clinical Trials|
|Drug Name||Trade Name||Synonyms||Drug Classes||Drug Description|
|Gene||Variant||Impact||Protein Effect||Variant Description||Associated with drug Resistance|
|DNMT3A||R882C||missense||loss of function - predicted||DNMT3A R882C lies within the SAM-dependent MTase C5-type domain of the Dnmt3a protein (UniProt.org). R882C has been associated with hypomethylation in patient samples (PMID: 24656771), and ectopic expression of R882C results in cytokine-independent growth, hypomethylation, and reduced apoptosis in cultured cells (PMID: 31164355, PMID: 30245403).|
|DNMT3A||R882H||missense||loss of function||DNMT3A R882H lies within the SAM-dependent MTase C5-type domain of the Dnmt3a protein (UniProt.org). R882H disrupts the tetramerization ability of the Dnmt3a protein, resulting in reduced DNA binding affinity and altered catalytic activity in in vitro assays (PMID: 22722925), and results in hypomethylation, cytokine-independent growth, and impaired differentiation in cultured cells (PMID: 31164355).|
|DNMT3A||R882S||missense||loss of function||DNMT3A R882S lies within the SAM-dependent MTase C5-type domain of the Dnmt3a protein (UniProt.org). R882S results in a loss of Dnmt3a protein function, as demonstrated by cytokine-independent growth and hypomethylation in cultured cells (PMID: 31164355).|
|Molecular Profile||Indication/Tumor Type||Response Type||Therapy Name||Approval Status||Evidence Type||Efficacy Evidence||References|
|DNMT3A R882H NRAS G12D||acute myeloid leukemia||sensitive||I-BET151 + Trametinib||Preclinical - Cell line xenograft||Actionable||In a preclinical study, an acute myeloid leukemia cell line xenograft model harboring DNMT3A R882H and NRAS G12D treated with combined I-BET151 and Mekinist (trametinib) demonstrated impaired disease progression and improved survival superior to either therapy alone (PMID: 31164355).||31164355|
|DNMT3A R882H NRAS G12D||acute myeloid leukemia||sensitive||I-BET151||Preclinical - Cell line xenograft||Actionable||In a preclinical study, an acute myeloid leukemia cell line harboring DNMT3A R882H and NRAS G12D mutations demonstrated reduced proliferation and downregulation of a DNMT3A R882H associated gene expression profile upon I-BET151 treatment in culture, and I-BET151 treatment delayed the onset of leukemia symptoms and improved survival in xenograft mouse models derived from these cells (PMID: 31164355).||31164355|
|DNMT3A R882H NRAS G12D||acute myeloid leukemia||sensitive||Trametinib||Preclinical - Cell line xenograft||Actionable||In a preclinical study, an acute myeloid leukemia cell line xenograft model harboring DNMT3A R882H and NRAS G12D was sensitive to Mekinist (trametinib), demonstrating impaired disease progression and improved survival (PMID: 31164355).||31164355|