Activating signaling mutations are common in acute leukemia with KMT2A (previously MLL) rearrangements. Herein, we show that co-expression of FLT3-N676K and KMT2A-MLLT3 in human CD34+ cord blood cells primarily cause acute myeloid leukemia (AML) and rarely acute lymphoblastic leukemia (ALL) in immunodeficient mice. By contrast, expression of KMT2A-MLLT3 alone cause ALL, double-positive leukemia (DPL, expressing both CD33 and CD19), or bilineal leukemia (BLL, comprised of distinct myeloid and lymphoid leukemia cells), and rarely AML. Further, AML could only be serially propagated with maintained immunophenotype in secondary recipients when cells co-expressed KMT2A-MLLT3 and FLT3-N676K. Consistent with the idea that activated signaling would allow myeloid cells to engraft and maintain their self-renewal capacity, in a secondary recipient, a de novo KRAS-G13D was identified in myeloid cells previously expressing only KMT2A-MLLT3. Gene expression profiling revealed that KMT2A-MLLT3 DPL had a highly similar gene expression profile to ALL, with both expressing key lymphoid transcription factors and ALL cell surface markers, in line with the DPL cells being ALL cells with aberrant expression of CD33. Taken together, our results highlight the need for constitutive active signaling mutations for driving myeloid leukemia in a human xenograft model of KMT2A-R acute leukemia. Overall design: mRNA sequencing of various immunophenotypic populations from KMT2A-MLLT3 xenograft leukemias with or without FLT3-N676K generated using Illumina NextSeq 500.
FLT3<sup>N676K</sup> drives acute myeloid leukemia in a xenograft model of KMT2A-MLLT3 leukemogenesis.
Specimen part, Subject
View SamplesActivating signaling mutations are common in acute leukemia with KMT2A (previously MLL) rearrangements (KMT2A-R). These mutations are often subclonal and their biological impact remains unclear. Using a retroviral acute myeloid mouse leukemia model, we demonstrate that FLT3ITD, FLT3N676K, and NRAS G12D accelerate KMT2A-MLLT3 leukemia onset. Subclonal FLT3N676K mutations also accelerate disease, possibly by providing stimulatory factors such as Mif. Acquired de novo mutations in Braf, Cbl, Kras, and Ptpn11 were identified in KMT2A-MLLT3 leukemia cells and favored clonal expansion. During clonal evolution, serial genetic changes at the KrasG12D locus was observed, consistent with a strong selective advantage of additional KrasG12D. KMT2A-MLLT3 leukemias with signaling mutations enforced Myc- and Myb transcriptional modules. Our results provide new insight into the biology of KMT2A-R leukemia with subclonal signaling mutations and highlights the importance of activated signaling as a contributing driver in this disease. Overall design: mRNA sequencing of KMT2A-MLLT3 leukemias with or without activating mutations generated using Illumina NextSeq 500.
De novo activating mutations drive clonal evolution and enhance clonal fitness in KMT2A-rearranged leukemia.
Specimen part, Cell line, Subject
View SamplesWe examined the gene expression profiles in ex vivo human CD4+ and CD8+ T cells from untreated HIV-infected individuals at different clinical stages and rates of disease progression. Profiles of pure CD4+ and CD8+ T cells subsets from HIV-infected nonprogressors who controlled viremia were indistinguishable from HIV-uninfected individuals. Similarly, no gene clusters could distinguish T cells from individuals with early from chronic progressive HIV infection, whereas differences were observed between uninfected or nonprogressors versus early or chronic progressors. In early/chronic HIV infection, three characteristic gene expression signatures were observed: (1) CD4+ and CD8+ T cells showed increased expression of interferon stimulated genes (ISGs). However, some ISGs including CXCL9, CXCL10, and CXCL11, and the IL15R in both CD4+ and CD8+ T cells and the anti-HIV ISG APOBEC3G in CD4+ T cells, were not upregulated. (2) CD4+ and CD8+ T cells showed a cluster similar to that observed in thymocytes, and (3) more genes were differentially regulated in CD8+ T cells than in CD4+ T cells, including a cluster of genes downregulated exclusively in CD8+ T cells. In conclusion, HIV infection induces a persistent T cell transcriptional profile, early in infection, characterized by a dramatic but potentially aberrant interferon response, and a profile suggesting an active thymic output.
Distinct transcriptional profiles in ex vivo CD4+ and CD8+ T cells are established early in human immunodeficiency virus type 1 infection and are characterized by a chronic interferon response as well as extensive transcriptional changes in CD8+ T cells.
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