Identification and interrogation of the gene regulatory network of CEBPA-double mutant acute myeloid leukemia

Mutant CEBPA promotes tolerance to inflammatory stress through deficient AP-1 activation

The CEBPA transcription factor is frequently mutated in acute myeloid leukemia (AML). Mutations in the CEBPA gene, which are typically biallelic, result in the production of a shorter isoform known as p30. Both the canonical 42-kDa isoform (p42) and the AML-associated p30 isoform bind chromatin and activate transcription, but the specific transcriptional programs controlled by each protein and how they are linked to a selective advantage in AML is not well understood. Here, we show that cells expressing the AML-associated p30 have reduced baseline inflammatory gene expression and display altered dynamics of transcriptional induction in response to LPS, consequently impacting cytokine secretion. This confers p30-expressing cells an increased resistance to the adverse effects of prolonged exposure to inflammatory signals. Mechanistically, we show that these differences primarily arise from the differential regulation of AP-1 family proteins. In addition, we find that the impaired function of the AP-1 member ATF4 in p30-expressing cells alters their response to ER stress. Collectively, these findings uncover a link between mutant CEBPA, inflammation and the stress response, potentially revealing a vulnerability in AML.

Diagnosis and typing of leukemia using a single peripheral blood cell through deep learning

Leukemia is highly heterogeneous, meaning that different types of leukemia require different treatments and have different prognoses. Current clinical diagnostic and typing tests are complex and time-consuming. In particular, all of these tests rely on bone marrow aspiration, which is invasive and leads to poor patient compliance, exacerbating treatment delays. Morphological analysis of peripheral blood cells (PBC) is still primarily used to distinguish between benign and malignant hematologic disorders, but it remains a challenge to diagnose and type these diseases solely by direct observation of peripheral blood(PB) smears by human experts. In this study, we apply a segmentation-based enhanced residual network that uses progressive multigranularity training with jigsaw patches. It is trained on a self-built annotated dataset of 21,208 images from 237 patients, including five types of benign white blood cells(WBCs) and eight types of leukemic cells. The network is not only able to discriminate between benign and malignant cells, but also to typify leukemia using a single peripheral blood cell. The network effectively differentiated acute promyelocytic leukemia (APL) from other types of acute myeloid leukemia (non-APL), achieving a precision rate of 89.34%, a recall rate of 97.37%, and an F1 score of 93.18% for APL. In contrast, for non-APL cases, the model achieved a precision rate of 92.86%, but a recall rate of 74.63% and an F1 score of 82.75%. In addition, the model discriminates acute lymphoblastic leukemia(ALL) with the Ph chromosome from those without. This approach could improve patient compliance and enable faster and more accurate typing of leukemias for early diagnosis and treatment to improve survival.

Flow cytometry in acute myeloid leukemia and detection of minimal residual disease

Acute myeloid leukemia (AML) is a common type of acute leukemia (AL), belonging to malignant tumors of the hematopoietic system with the characteristics of rapid disease development, control with extreme difficulties, easy recurrence, poor prognosis, and incidence rate increasing with age. The traditionally diagnostic standard of French American British (FAB), being based on the morphological examination with high human subjectivity, can no longer meet the demand of clinical diagnosis and treatment of AML. Requirements of objective accuracy and low-dose sample, have become the indispensable method for AML diagnosis and monitoring prognosis. Flow cytometry is a modern technology that can quickly and accurately detect the series, antigen distribution, differentiation stage of AML cells, minimal residual lesions after AML therapy, so as to provide the great significance in guiding clinical diagnosis, hierarchical treatment, and prognosis judgement. This article will systematically elaborate on the application of flow cytometry in the diagnosis and classification of AML, and the detection of minimal residual lesions, thereby providing reference significance for dynamic monitoring and prognostic observation of AML with different immune subtypes of FAB.

Molecular profiling unveils pyroptosis markers in preterm birth

Through a comprehensive examination of pyroptosis-related differential expressed genes (PRDEGs), this work investigates the molecular complexities of spontaneous preterm birth (SPTB), also known as premature delivery, before the due date. Through the process of merging and correcting batch effects in the GSE120480 and GSE73714 datasets, we were able to identify 36 PRDEGs that exhibited significant expression differentiation in SPTB. Through functional enrichment and pathway analysis, their importance in amino acid transport and cytokine receptor interaction has been highlighted. Among the genes that have emerged as crucial, CEBPA, APOA1, and CEP55 have been identified. The relevance of these molecules was demonstrated using experimental knockdowns, which also suggested that they could be used as molecular biomarkers and therapeutic targets for SPTB.

CEBPA mutations in acute myeloid leukemia: implications in risk stratification and treatment

Mutations in CCAAT enhancer binding protein α (CEBPA) occur in approximately 10% of patients with de novo acute myeloid leukemia (AML). Emerging evidence supports that in-frame mutations in the basic leucine zipper domain of CEBPA (CEBPAbZIP-inf) confer a survival benefit, and CEBPAbZIP-inf replaced CEBPA double mutations (CEBPAdm) as a unique entity in the 2022 World Health Organization (WHO-2022) classification and International Consensus Classification (ICC). However, challenges remain in daily clinical practice since more than 30% patients with CEBPAbZIP-inf die of AML despite intensive treatment. This review aims to provide a comprehensive summary of the heterogeneities observed in AML with CEBPAdm and CEBPAbZIP-inf, and will discuss the prognostic implications of concurrent mutations and novel mechanistic targets that may inform future drug development. The ultimate goal is to optimize clinical management and to provide precision medicine for this category of patients.

Regulation of developmentally controlled enhancer activity by extrinsic signals in normal and malignant cells: AP-1 at the centre

The ability of cells to respond to external stimuli is one of the characteristics of life as we know it. Multicellular organisms have developed a huge machinery that interprets the cellular environment and instigates an appropriate cellular response by changing gene expression, metabolism, proliferation state and motility. Decades of research have studied the pathways transmitting the various signals within the cell. However, whilst we know most of the players, we know surprisingly little about the mechanistic details of how extrinsic signals are interpreted and integrated within the genome. In this article we revisit the long-standing debate of whether factors regulating cellular growth (cytokines) act in an instructive or permissive fashion on cell fate decisions. We touch upon this topic by highlighting the paradigm of AP-1 as one of the most important signaling-responsive transcription factor family and summarize our work and that of others to explain what is known about cytokine responsive cis-regulatory elements driving differential gene expression. We propose that cytokines and, by extension, multiple types of external signals are the main drivers of cell differentiation and act via inducible transcription factors that transmit signaling processes to the genome and are essential for changing gene expression to drive transitions between gene regulatory networks. Importantly, inducible transcription factors cooperate with cell type specific factors within a pre-existing chromatin landscape and integrate multiple signaling pathways at specific enhancer elements, to both maintain and alter cellular identities. We also propose that signaling processes and signaling responsive transcription factors are at the heart of tumor development.

Impact of different CEBPA mutations on therapeutic outcome in acute myeloid leukemia

Biallelic mutations of the CEBPA gene (CEBPAbi) are generally associated with favorable prognosis in patients with acute myeloid leukemia (AML). Monoallelic mutations of the CEBPA gene in carboxy-terminal DNA-binding region (CEBPAsmbZIP) and amino-terminal transactivation domains (CEBPAsmTAD) indicate distinct clinical characteristics and therapeutic outcomes. However, further investigation is required to fully understand these differences. In this retrospective study, we enrolled 77 AML patients with CEBPA mutations, including 53 with CEBPAbi, 12 with CEBPAsmbZIP and 12 with CEBPAsmTAD. The clinical characteristics of the three CEBPAmut groups presented significant differences in age, FAB classification, hemoglobin level and platelet count at diagnosis. The CEBPAsmTAD group exhibited shorter 2-year overall survival (OS) and relapse-free survival (RFS) compared to the CEBPAbi group and CEBPAsmbZIP group in AML patients. The most common co-mutations observed in CEBPAmut AML patients were TET2 and GATA2, which had no effect on prognosis. 2-year RFS of 27 CEBPAmut AML patients who underwent allo-HSCT was better than those who did not. MRD3 positive was identified as an influencing factor for 2-year OS and RFS. Allo-HSCT was found to improve the prognosis of CEPBAmut AML patients with positive MRD3 and adverse co-mutations.

Leukemic stem cells activate lineage inappropriate signalling pathways to promote their growth

Acute Myeloid Leukemia (AML) is caused by multiple mutations which dysregulate growth and differentiation of myeloid cells. Cells adopt different gene regulatory networks specific to individual mutations, maintaining a rapidly proliferating blast cell population with fatal consequences for the patient if not treated. The most common treatment option is still chemotherapy which targets such cells. However, patients harbour a population of quiescent leukemic stem cells (LSCs) which can emerge from quiescence to trigger relapse after therapy. The processes that allow such cells to re-grow remain unknown. Here, we examine the well characterised t(8;21) AML sub-type as a model to address this question. Using four primary AML samples and a novel t(8;21) patient-derived xenograft model, we show that t(8;21) LSCs aberrantly activate the VEGF and IL-5 signalling pathways. Both pathways operate within a regulatory circuit consisting of the driver oncoprotein RUNX1::ETO and an AP-1/GATA2 axis allowing LSCs to re-enter the cell cycle while preserving self-renewal capacity.

A C/ebpα isoform specific differentiation program in immortalized myelocytes

The transcription factor CCAAT-enhancer binding factor alpha (C/ebpα) is a master controller of myeloid differentiation that is expressed as long (p42) and short (p30) isoform. Mutations within the CEBPA gene selectively deleting p42 are frequent in human acute myeloid leukemia. Here we investigated the individual genomics and transcriptomics of p42 and p30. Both proteins bound to identical sites across the genome. For most targets, they induced a highly similar transcriptional response with the exception of a few isoform specific genes. Amongst those we identified early growth response 1 (Egr1) and tribbles1 (Trib1) as key targets selectively induced by p42 that are also underrepresented in CEBPA-mutated AML. Egr1 executed a program of myeloid differentiation and growth arrest. Oppositely, Trib1 established a negative feedback loop through activation of Erk1/2 kinase thus placing differentiation under control of signaling. Unexpectedly, differentiation elicited either by removal of an oncogenic input or by G-CSF did not peruse C/ebpα as mediator but rather directly affected the cell cycle core by upregulation of p21/p27 inhibitors. This points to functions downstream of C/ebpα as intersection point where transforming and differentiation stimuli converge and this finding offers a new perspective for therapeutic intervention.