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Acute myeloid leukemia is a genetically and cellularly heterogeneous disease. We characterize 120 AMLs using genomic and transcriptomic analyses, including single-cell RNA sequencing. Our results reveal an extensive cellular heterogeneity that distorts the bulk transcriptomic profiles. Selective examination of the transcriptional signatures of >90,000 immature AML cells identifies four main clusters, thereby extending current genomic classification of AML. Notably, NPM1-mutated AML can be stratified into two clinically relevant classes, with NPM1class I associated with downregulation of MHC class II and excellent survival following hematopoietic stem cell transplantation. NPM1class II is instead associated with resistance to allogeneic T cells in an ex vivo co-culture assay, and importantly, dismal survival following hematopoietic stem cell transplantation. These findings provide insights into the cellular state space of AML, define diagnostic entities, and highlight potential therapeutic intervention points. The clinical outcomes and treatment responses of acute myeloid leukemia (AML) patients are heterogeneous. Here, the authors use bulk and single-cell sequencing approaches and identify two transcriptomic subtypes within NPM1-mutated AML with distinct immune evasion properties and responses to hematopoietic stem cell transplantation.

Mucopolysaccharidosis (MPS) IVA is a bone-affecting lysosomal storage disease (LSD) caused by impaired degradation of the glycosaminoglycans (GAGs) keratan sulfate (KS) and chondroitin 6-sulfate (C6S) due to deficient N-acetylgalactosamine-6-sulfatase (GALNS) enzyme activity. Previously, we successfully developed and validated a CRISPR/nCas9-based gene therapy (GT) to insert an expression cassette at the AAVS1 and ROSA26 loci in human MPS IVA fibroblasts and MPS IVA mice, respectively. In this study, we have extended our approach to evaluate the effectiveness of our CRISPR/nCas9-based GT in editing human CD34+ cells to mediate cross-correction of MPS IVA fibroblasts. CD34+ cells were electroporated with the CRISPR/nCas9 system, targeting the AAVS1 locus. The nCas9-mediated on-target donor template insertion, and the stemness of the CRISPR/nCas-edited CD34+ cells was evaluated. Additionally, MPS IVA fibroblasts were co-cultured with CRISPR/nCas-edited CD34+ cells to assess cross-correction. CRISPR/nCas9-based gene editing did not affect the stemness of CD34+ cells but did lead to supraphysiological levels of the GALNS enzyme. Upon co-culture, MPS IVA fibroblasts displayed a significant increase in the GALNS enzyme activity along with lysosomal mass reduction, pro-oxidant profile amelioration, mitochondrial mass recovery, and pro-apoptotic and pro-inflammatory profile improvement. These results show the potential of our CRISPR/nCas9-based GT to edit CD34+ cells to mediate cross-correction.

MED12 is a key regulator of transcription and chromatin architecture, essential for normal hematopoiesis. While its dysregulation has been implicated in hematological malignancies, the mechanisms driving its upregulation in acute myeloid leukemia (AML) remain poorly understood. We investigated MED12 expression across AML subgroups by integrating chromatin accessibility profiling, histone modification landscapes, and DNA methylation (DNAm) patterns. Functional assays using DNMT inhibition were performed to dissect the underlying regulatory mechanisms. MED12 shows subtype-specific upregulation in AML compared to hematopoietic stem and progenitor cells, independent of somatic mutations. Chromatin accessibility profiling reveals that the MED12 locus is epigenetically primed in AML blasts, with increased DNase hypersensitivity at regulatory elements. Histone modification analysis demonstrates strong H3K4me3 and H3K27ac enrichment around the transcription start site (TSS), consistent with promoter activation, while upstream and intragenic regions exhibit enhancer-associated marks (H3K4me1, H3K27ac). Notably, hypermethylation within TSS-proximal regulatory regions (TPRRs)—including promoter-overlapping and adjacent CpG islands—correlates with ectopic MED12 overexpression, challenging the canonical view of DNAm as strictly repressive. Functional studies show that DNMT inhibition via 5-azacytidine reduces MED12 expression despite promoter demethylation in cells with hypermethylated TPRRs, suggesting a noncanonical role for DNA methylation in maintaining active transcription. Furthermore, MED12 expression positively correlates with DNMT3A and DNMT3B expression, implicating these methyltransferases in sustaining its epigenetic activation. This study identifies a novel regulatory axis in which aberrant DNA methylation, rather than genetic mutation, drives MED12 upregulation in AML. Our findings suggest that TPRR hypermethylation may function noncanonically to support transcriptional activation, likely in cooperation with enhancer elements. These results underscore the importance of epigenetic mechanisms in AML and highlight enhancer-linked methylation as a potential contributor to oncogene dysregulation. Future studies should further explore the role of noncanonical methylation-mediated gene activation in AML pathogenesis and therapeutic targeting. The online version contains supplementary material available at 10.1186/s13072-025-00610-9.