Project description:Clonal hematopoiesis (CH) is an aging-associated condition characterized by the clonal outgrowth of mutated preleukemic cells. Individuals with CH are at an increased risk of developing hematopoietic malignancies. Here, we describe a novel animal model carrying a recurrent TET2 missense mutation frequently found in patients with CH and leukemia. In a fashion similar to CH, animals show signs of disease late in life when they develop a wide range of myeloid neoplasms, including acute myeloid leukemia (AML). Using single-cell transcriptomic profiling of the bone marrow, we show that disease progression in aged animals correlates with an enhanced inflammatory response and the emergence of an aberrant inflammatory monocytic cell population. The gene signature characteristic of this inflammatory population is associated with poor prognosis in patients with AML. Our study illustrates an example of collaboration between a genetic lesion found in CH and inflammation, leading to transformation and the establishment of blood neoplasms.SignificanceProgression from a preleukemic state to transformation, in the presence of TET2 mutations, is coupled with the emergence of inflammation and a novel population of inflammatory monocytes. Genes characteristic of this inflammatory population are associated with the worst prognosis in patients with AML. These studies connect inflammation to progression to leukemia. See related commentary by Pietras and DeGregori, p. 2234 . This article is highlighted in the In This Issue feature, p. 2221.
| S-EPMC9547930 | biostudies-literature
Project description:The impact of inflammation-induced tumor plasticity during myeloid transformation
Project description:Driver somatic mutations in adult acute myeloid leukemia (AML) are often preceded by a benign or premalignant state termed clonal hematopoiesis (CH) for which the greatest risk factor is aging. To risk-stratify aged individuals and develop therapies to prevent AML, we need to understand the variables that promote transformation from CH to AML. Using our orthogonally inducible Dnmt3aR878H;Npm1cA-mutant model of progression from CH to myeloid malignancy, we find that in young mice, Dnmt3a mutation buffers against myeloid differentiation, proliferation, acquisition of cooperating mutations and transformation induced by stress, inflammation, and the oncogenic Npm1 mutation. However, when Dnmt3a;Npm1-mutant hematopoietic stem cells (HSCs) are transplanted into naturally aged recipient mice, they gain myeloid-biased differentiation capacity and have an accelerated transformation to AML. These results support the hypothesis that alterations in the aged microenvironment drive risk of AML in individuals with CH and help to explain why this Dnmt3a mutation is exceedingly rare in pediatric leukemias.
Project description:Recurrent somatic mutations in TET2 and in other genes that regulate the epigenetic state have been identified in patients with myeloid malignancies and in other cancers. However, the in vivo effects of Tet2 loss have not been delineated. We report here that Tet2 loss leads to increased stem-cell self-renewal and to progressive stem cell expansion. Consistent with human mutational data, Tet2 loss leads to myeloproliferation in vivo, notable for splenomegaly and monocytic proliferation. In addition, haploinsufficiency for Tet2 confers increased self-renewal and myeloproliferation, suggesting that the monoallelic TET2 mutations found in most TET2-mutant leukemia patients contribute to myeloid transformation. This work demonstrates that absent or reduced Tet2 function leads to enhanced stem cell function in vivo and to myeloid transformation. These studies show that a ubiquitin ligase-substrate pair can orchestrate the molecular program of HSC differentitiation Gene expression profiles from WT and Tet2-/- sorted LSK and myeloid progenitors (CMP and GMP) were compared using genome wide mRNA expression profiling by Affymetrix genechip arrays (Mouse 430 2.0) and key targets were validated by chromatin immunoprecipitation experiments.