Characterization of bone marrow heterogeneity in NK-AML (M4/M5) based on single-cell RNA sequencing

High-throughput single cell -omics using semi-permeable capsules

Biological systems are inherently complex and heterogeneous. Deciphering this complexity increasingly relies on high-throughput analytical methods and tools that efficiently probe the cellular phenotype and genotype. While recent advancements have enabled various single-cell -omics assays, their broader applications are inherently limited by the challenge of efficiently conducting multi-step biochemical assays while retaining various biological analytes. Extending on our previous work (1) here we present a versatile technology based on semi-permeable capsules (SPCs), tailored for a variety of high-throughput nucleic acid assays, including digital PCR, genome sequencing, single-cell RNA-sequencing (scRNA-Seq) and FACS-based isolation of individual transcriptomes based on nucleic acid marker of interest. Being biocompatible, the SPCs support single-cell cultivation and clonal expansion over long periods of time - a fundamental limitation of droplet microfluidics systems. Using SPCs we perform scRNA-Seq on white blood cells from patients with hematopoietic disorders and demonstrate that capsule-based sequencing approach (CapSeq) offers superior transcript capture, even for the most challenging cell types. By applying CapSeq on acute myeloid leukemia (AML) samples, we uncover notable changes in transcriptomes of mature granulocytes and monocytes associated with blast and progenitor cell phenotypes. Accurate representation of the entirety of the cellular heterogeneity of clinical samples, driving new insights into the malfunctioning of the innate immune system, and ability to clonally expand individual cells over long periods of time, positions SPC technology as customizable, highly sensitive and broadly applicable tool for easy-to-use, scalable single-cell -omics applications.

Molecular profiling of skin cells identifies distinct cellular signatures in radiation-induced skin injury across various stages in the murine dataset

BACKGROUND

Radiation-induced skin injury (RISI) commonly manifests in cancer patients undergoing radiotherapy (RT). However, a universally accepted standard for treating radiation injury has not yet been established. Our objective was to provide a detailed molecular overview of skin pre- and post-radiation therapy, aiming to enhance our understanding of the subclusters and molecular mechanisms contributing to radiodermatitis.

METHODS

C57BL/6 mice were subjected to a single fraction (20 Gy) of RT targeting the right dorsal skin. We then employed integrated single-cell RNA sequencing (scRNA-seq) to analyze skin samples from mice at 7 and 30 days after radiation exposure, as well as from non-irradiated mice. The Seurat analysis pipeline, Cellchat, SCP, and ssGSEA were used to define the cell types and mechanisms involved in radiation-induced skin injury. Reverse transcription polymerase chain reaction (RT-PCR), multiplex immunofluorescent staining, and other datasets (GSE130183, GSE193564, and GSE193807) were used to validate our findings.

RESULTS

Thirty-two distinct cell clusters encompassing 71,412 cells were identified. We discovered that cycling keratinocytes (KCs), with the BMP signaling pathway enriched, could activate the Wnt pathway, as well as the SMAD pathways, driving the wound healing and fibrosis processes in RISI. Terminally differentiated secretory-papillary fibroblasts (Fibs) are capable of attracting immune cells, which contributes to the pathogenesis of RISI. Lymphatic endothelial cells (ECs) with pro-inflammatory properties play a critical role in the pathogenesis of RISI by facilitating leukocyte migration. Our analysis also highlighted enhanced ligand-receptor interactions, notably the interactions between chemokines like CXCL10, CCL2, and ACKR1, across subclusters of inflammatory KCs, Fibs, ECs, and immune cells, underscoring their pivotal role in leukocyte recruitment in RISI.

CONCLUSIONS

Cycling KCs, secretory-papillary Fibs, and lymphatic ECs play critical roles in RISI progression. Targeting the interactions of these subclusters with immune cells might help improve the severity of RISI. Furthermore, our study provides a valuable resource for understanding the interactions among immune cells in the context of RISI.

Inhibition of TOX exerts anti-tumor effects in acute myeloid leukemia by upregulating IRF7 expression

Thymocyte selection-associated high mobility group box protein (TOX) is regarded as a crucial transcription factor involved in T cell exhaustion in acute myeloid leukemia (AML). Previous studies have identified aberrant TOX expression as a major oncogenic driver in hematologic malignancies, indicating that TOX may potentially be both an immune biomarker and an immunotherapy target. However, due to heterogeneity in the distribution patterns of TOX and its correlation with clinical prognosis, the mechanism underlying TOX-mediated tumor immune responses remains unclear. In this study, we demonstrate that high TOX expression in AML patients is associated with poor prognosis, and TOX overexpression promotes AML cell proliferation and restricts apoptosis. In vitro TOX inhibition promoted the apoptosis of AML cells, suppressed cell viability, and induced cell cycle arrest in the G0/G1 phase. Moreover, TOX knockdown could reduce tumor burden in vivo in immunodeficient mice and prolong their survival. Furthermore, the anti-AML effects of inhibiting TOX may act through activation of the IFN-α signal pathway and upregulating IRF7 expression. In summary, we report for the first time that TOX knockdown exerts powerful anti-tumor effects in AML. These findings will provide a theoretical basis for targeted therapy in AML patients.

Unlocking reproducible transcriptomic signatures for acute myeloid leukaemia: Integration, classification and drug repurposing

Acute myeloid leukaemia (AML) is a highly heterogeneous disease, which lead to various findings in transcriptomic research. This study addresses these challenges by integrating 34 datasets, including 26 control groups, 6 prognostic datasets and 2 single-cell RNA sequencing (scRNA-seq) datasets to identify 10,000 AML-related genes (ARGs). We focused on genes with low variability and high consistency and successfully discovered 191 AML signatures (ASs). Leveraging machine learning techniques, specifically the XGBoost model and our custom framework, we classified AML subtypes with both scRNA-seq and bulk RNA-seq data, complementing the ELN2022 classification approach. Our research also identified promising treatments for AML through drug repurposing, with solasonine showing potential efficacy for high-risk AML patients, supported by molecular docking and transcriptomic analyses. To enhance reproducibility and customizability, we developed CSAMLdb, a user-friendly database platform. It facilitates the reuse and personalized analysis of nearly all results obtained in this research, including single-gene prognostics, multi-gene scoring, enrichment analysis, machine learning risk assessment, drug repositioning analysis and literature abstract named entity recognition. CSAMLdb is available at http://www.csamldb.com.

Unveiling novel insights in acute myeloid leukemia through single-cell RNA sequencing

Acute myeloid leukemia (AML) is a complex and heterogeneous group of aggressive hematopoietic stem cell disease. The presence of diverse and functionally distinct populations of leukemia cells within the same patient's bone marrow or blood poses a significant challenge in diagnosing and treating AML. A substantial proportion of AML patients demonstrate resistance to induction chemotherapy and a grim prognosis upon relapse. The rapid advance in next generation sequencing technologies, such as single-cell RNA-sequencing (scRNA-seq), has revolutionized our understanding of AML pathogenesis by enabling high-resolution interrogation of the cellular heterogeneity in the AML ecosystem, and their transcriptional signatures at a single-cell level. New studies have successfully characterized the inextricably intertwined interactions among AML cells, immune cells and bone marrow microenvironment and their contributions to the AML development, therapeutic resistance and relapse. These findings have deepened and broadened our understanding the complexity and heterogeneity of AML, which are difficult to detect with bulk RNA-seq. This review encapsulates the burgeoning body of knowledge generated through scRNA-seq, providing the novel insights and discoveries it has unveiled in AML biology. Furthermore, we discuss the potential implications of scRNA-seq in therapeutic opportunities, focusing on immunotherapy. Finally, we highlight the current limitations and future direction of scRNA-seq in the field.

A novel AML1-ETO/FTO positive feedback loop promotes leukemogenesis and Ara-C resistance via stabilizing IGFBP2 in t(8;21) acute myeloid leukemia

BACKGROUND

t(8;21)(q22;q22) is one of the most frequent chromosomal abnormalities in acute myeloid leukemia (AML), leading to the generation of the fusion protein AML1-ETO. Despite t(8;21) AML being considered as a subtype with a favorable prognosis, approximately 30-50% of patients experience drug resistance and subsequent relapse. N6-methyladenosine (m6A) is demonstrated to be involved in the development of AML. However, the regulatory mechanisms between AML1-ETO and m6A-related enzymes and the roles of dysregulated m6A modifications in the t(8;21)-leukemogenesis and chemoresistance remain elusive.

METHODS

Chromatin immunoprecipitation, dual-luciferase reporter assay, m6A-qPCR, RNA immunoprecipitation, and RNA stability assay were used to investigate a regulatory loop between AML1-ETO and FTO, an m6A demethylase. Gain- and loss-of-function experiments both in vitro and in vivo were further performed. Transcriptome-wide RNA sequencing and m6A sequencing were conducted to identify the potential targets of FTO.

RESULTS

Here we show that FTO is highly expressed in t(8;21) AML, especially in patients with primary refractory disease. The expression of FTO is positively correlated with AML1-ETO, which is attributed to a positive regulatory loop between the AML1-ETO and FTO. Mechanistically, AML1-ETO upregulates FTO expression through inhibiting the transcriptional repression of FTO mediated by PU.1. Meanwhile, FTO promotes the expression of AML1-ETO by inhibiting YTHDF2-mediated AML1-ETO mRNA decay. Inactivation of FTO significantly suppresses cell proliferation, promotes cell differentiation and renders resistant t(8;21) AML cells sensitive to Ara-C. FTO exerts functions by regulating its mRNA targets, especially IGFBP2, in an m6A-dependent manner. Regain of Ara-C tolerance is observed when IGFBP2 is overexpressed in FTO-knockdown t(8;21) AML cells.

CONCLUSION

Our work reveals a therapeutic potential of targeting AML1-ETO/FTO/IGFBP2 minicircuitry in the treatment for t(8;21) patients with resistance to Ara-C.

Advances in single-cell RNA sequencing and its applications in cancer research

Cancers are a group of heterogeneous diseases characterized by the acquisition of functional capabilities during the transition from a normal to a neoplastic state. Powerful experimental and computational tools can be applied to elucidate the mechanisms of occurrence, progression, metastasis, and drug resistance; however, challenges remain. Bulk RNA sequencing techniques only reflect the average gene expression in a sample, making it difficult to understand tumor heterogeneity and the tumor microenvironment. The emergence and development of single-cell RNA sequencing (scRNA-seq) technologies have provided opportunities to understand subtle changes in tumor biology by identifying distinct cell subpopulations, dissecting the tumor microenvironment, and characterizing cellular genomic mutations. Recently, scRNA-seq technology has been increasingly used in cancer studies to explore tumor heterogeneity and the tumor microenvironment, which has increased the understanding of tumorigenesis and evolution. This review summarizes the basic processes and development of scRNA-seq technologies and their increasing applications in cancer research and clinical practice.