JMJD1C-mediated metabolic dysregulation contributes to HOXA9-dependent leukemogenesis

Loss of the stress sensor GADD45A promotes stem cell activity and ferroptosis resistance in LGR4/HOXA9-dependent AML

ABSTRACT

The overall prognosis of acute myeloid leukemia (AML) remains dismal, largely because of the inability of current therapies to kill leukemia stem cells (LSCs) with intrinsic resistance. Loss of the stress sensor growth arrest and DNA damage-inducible 45 alpha (GADD45A) is implicated in poor clinical outcomes, but its role in LSCs and AML pathogenesis is unknown. Here, we define GADD45A as a key downstream target of G protein-coupled receptor (LGR)4 pathway and discover a regulatory role for GADD45A loss in promoting leukemia-initiating activity and oxidative resistance in LGR4/HOXA9-dependent AML, a poor prognosis subset of leukemia. Knockout of GADD45A enhances AML progression in murine and patient-derived xenograft (PDX) mouse models. Deletion of GADD45A induces substantial mutations, increases LSC self-renewal and stemness in vivo, and reduces levels of reactive oxygen species (ROS), accompanied by a decreased response to ROS-associated genotoxic agents (eg, ferroptosis inducer RSL3) and acquisition of an increasingly aggressive phenotype on serial transplantation in mice. Our single-cell cellular indexing of transcriptomes and epitopes by sequencing analysis on patient-derived LSCs in PDX mice and subsequent functional studies in murine LSCs and primary AML patient cells show that loss of GADD45A is associated with resistance to ferroptosis (an iron-dependent oxidative cell death caused by ROS accumulation) through aberrant activation of antioxidant pathways related to iron and ROS detoxification, such as FTH1 and PRDX1, upregulation of which correlates with unfavorable outcomes in patients with AML. These results reveal a therapy resistance mechanism contributing to poor prognosis and support a role for GADD45A loss as a critical step for leukemia-initiating activity and as a target to overcome resistance in aggressive leukemia.

Epigenetic roles of KDM3B and KDM3C in tumorigenesis and their therapeutic implications

Advances in functional studies on epigenetic regulators have disclosed the vital roles played by diverse histone lysine demethylases (KDMs), ranging from normal development to tumorigenesis. Most of the KDMs are Jumonji C domain-containing (JMJD) proteins. Many of these KDMs remove methyl groups from histone tails to regulate gene transcription. There are more than 30 known KDM proteins, which fall into different subfamilies. Of the many KDM subfamilies, KDM3 (JMJD1) proteins specifically remove dimethyl and monomethyl marks from lysine 9 on histone H3 and other non-histone proteins. Dysregulation of KDM3 proteins leads to infertility, obesity, metabolic syndromes, heart diseases, and cancers. Among the KDM3 proteins, KDM3A has been largely studied in cancers. However, despite a number of studies pointing out their importance in tumorigenesis, KDM3B and KDM3C are relatively overlooked. KDM3B and KDM3C show context-dependent functions, showing pro- or anti-tumorigenic abilities in different cancers. Thus, this review provides a thorough understanding of the involvement of KDM3B and KDMC in oncology that should be helpful in determining the role of KDM3 proteins in preclinical studies for development of novel pharmacological methods to overcome cancer.

The emerging roles of histone demethylases in cancers

Modulation of histone methylation status is regarded as an important mechanism of epigenetic regulation and has substantial clinical potential for the therapy of diseases, including cancer and other disorders. The present study aimed to provide a comprehensive introduction to the enzymology of histone demethylases, as well as their cancerous roles, molecular mechanisms, therapeutic possibilities, and challenges for targeting them, in order to advance drug design for clinical therapy and highlight new insight into the mechanisms of these enzymes in cancer. A series of clinical trials have been performed to explore potential roles of histone demethylases in several cancer types. Numerous targeted inhibitors associated with immunotherapy, chemotherapy, radiotherapy, and targeted therapy have been used to exert anticancer functions. Future studies should evaluate the dynamic transformation of histone demethylases leading to carcinogenesis and explore individual therapy.

Metabolic dependencies of acute myeloid leukemia stem cells

Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy primarily driven by an immature population of AML cells termed leukemia stem cells (LSCs) that are implicated in AML development, chemoresistance, and relapse. An emerging area of research in AML focuses on identifying and targeting the aberrant metabolism in LSCs. Dysregulated metabolism is involved in sustaining functional properties of LSCs, impeding myeloid differentiation, and evading programmed cell death, both in the process of leukemogenesis and in response to chemotherapy. This review discusses recent discoveries regarding the aberrant metabolic processes of AML LSCs that have begun to change the therapeutic landscape of AML.

Silencing of Jumonji domain-containing 1C inhibits the osteogenic differentiation of bone marrow mesenchymal stem cells via nuclear factor-κB signaling

BACKGROUND

Osteoporosis is a common metabolic bone disorder induced by an imbalance between osteoclastic activity and osteogenic activity. During osteoporosis, bone mesenchymal stem cells (BMSCs) exhibit an increased ability to differentiate into adipocytes and a decreased ability to differentiate into osteoblasts, resulting in bone loss. Jumonji domain-containing 1C (JMJD1C) has been demonstrated to suppress osteoclastogenesis.

AIM

To examine the effect of JMJD1C on the osteogenesis of BMSCs and the potential underlying mechanism.

METHODS

BMSCs were isolated from mouse bone marrow tissues. Oil Red O staining, Alizarin red staining, alkaline phosphatase staining and the expression of adipogenic and osteogenic-associated genes were assessed to determine the differentiation of BMSCs. Bone marrow-derived macrophages (BMMs) were incubated with receptor activator of nuclear factor-kappa Β ligand to induce osteoclast differentiation, and osteoclast differentiation was confirmed by tartrate-resistant acid phosphatase staining. Other related genes were measured via reverse transcription coupled to the quantitative polymerase chain reaction and western blotting. Enzyme-linked immunosorbent assays were used to measure the levels of inflammatory cytokines, including tumor necrosis factor alpha, interleukin-6 and interleukin-1 beta.

RESULTS

The osteogenic and adipogenic differentiation potential of BMSCs isolated from mouse bone marrow samples was evaluated. JMJD1C mRNA and protein expression was upregulated in BMSCs after osteoblast induction, while p-nuclear factor-κB (NF-κB) and inflammatory cytokines were not significantly altered. Knockdown of JMJD1C repressed osteogenic differentiation and enhanced NF-κB activation and inflammatory cytokine release in BMSCs. Moreover, JMJD1C expression decreased during BMM osteoclast differentiation.

CONCLUSION

The JMJD1C/NF-κB signaling pathway is potentially involved in BMSC osteogenic differentiation and may play vital roles in the pathogenesis of osteoporosis.

Bidirectional interplay between metabolism and epigenetics in hematopoietic stem cells and leukemia

During the last decades, remarkable progress has been made in further understanding the complex molecular regulatory networks that maintain hematopoietic stem cell (HSC) function. Cellular and organismal metabolisms have been shown to directly instruct epigenetic alterations, and thereby dictate stem cell fate, in the bone marrow. Epigenetic regulatory enzymes are dependent on the availability of metabolites to facilitate DNA- and histone-modifying reactions. The metabolic and epigenetic features of HSCs and their downstream progenitors can be significantly altered by environmental perturbations, dietary habits, and hematological diseases. Therefore, understanding metabolic and epigenetic mechanisms that regulate healthy HSCs can contribute to the discovery of novel metabolic therapeutic targets that specifically eliminate leukemia stem cells while sparing healthy HSCs. Here, we provide an in-depth review of the metabolic and epigenetic interplay regulating hematopoietic stem cell fate. We discuss the influence of metabolic stress stimuli, as well as alterations occurring during leukemic development. Additionally, we highlight recent therapeutic advancements toward eradicating acute myeloid leukemia cells by intervening in metabolic and epigenetic pathways.

Histone Demethylase Modulation: Epigenetic Strategy to Combat Cancer Progression

Epigenetic modifications are heritable, reversible changes in histones or the DNA that control gene functions, being exogenous to the genomic sequence itself. Human diseases, particularly cancer, are frequently connected to epigenetic dysregulations. One of them is histone methylation, which is a dynamically reversible and synchronously regulated process that orchestrates the three-dimensional epigenome, nuclear processes of transcription, DNA repair, cell cycle, and epigenetic functions, by adding or removing methylation groups to histones. Over the past few years, reversible histone methylation has become recognized as a crucial regulatory mechanism for the epigenome. With the development of numerous medications that target epigenetic regulators, epigenome-targeted therapy has been used in the treatment of malignancies and has shown meaningful therapeutic potential in preclinical and clinical trials. The present review focuses on the recent advances in our knowledge on the role of histone demethylases in tumor development and modulation, in emphasizing molecular mechanisms that control cancer cell progression. Finally, we emphasize current developments in the advent of new molecular inhibitors that target histone demethylases to regulate cancer progression.

Sf3b4 regulates chromatin remodeler splicing and Hox expression

SF3B proteins form a heptameric complex in the U2 small nuclear ribonucleoprotein, essential for pre-mRNA splicing. Heterozygous pathogenic variants in human SF3B4 are associated with head, face, limb, and vertebrae defects. Using the CRISPR/Cas9 system, we generated mice with constitutive heterozygous deletion of Sf3b4 and showed that mutant embryos have abnormal vertebral development. Vertebrae abnormalities were accompanied by changes in levels and expression pattern of Hox genes in the somites. RNA sequencing analysis of whole embryos and somites of Sf3b4 mutant and control litter mates revealed increased expression of other Sf3b4 genes. However, the mutants exhibited few differentially expressed genes and a large number of transcripts with differential splicing events (DSE), predominantly increased exon skipping and intron retention. Transcripts with increased DSE included several genes involved in chromatin remodeling that are known to regulate Hox expression. Our study confirms that Sf3b4 is required for normal vertebrae development and shows, for the first time, that like Sf3b1, Sf3b4 also regulates Hox expression. We propose that abnormal splicing of chromatin remodelers is primarily responsible for vertebral defects found in Sf3b4 heterozygous mutant embryos.

JMJD1C promotes smooth muscle cell proliferation by activating glycolysis in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic disorder characterized by hyperproliferation of pulmonary arterial smooth muscle cells (PASMCs). JMJD1C, a member of the Jumonji domain containing C (JMJC) histone demethylase family, contributes to cardiovascular dysfunction. However, the role of JMJD1C in PAH remains unknown. Mice were exposed to hypoxia to mimic several features associated with PAH clinically. We found that JMJD1C was highly expressed in the lungs of mice after hypoxia exposure. JMJD1C knockdown ameliorated hypoxia-induced right ventricular remodeling and thickening of the pulmonary arterial wall. PASMC hyperproliferation and resistance to apoptosis in mice exposed to hypoxia were suppressed by JMJD1C inhibition. We demonstrated that JMJD1C silencing reduced glycolytic enzymes (HK2, PGK1 and LDHA) and lactate overaccumulation in the lungs of mice exposed to hypoxia. In vitro, hypoxia-induced hyperproliferation and activated glycolytic processes in mouse PASMCs were impaired by JMJD1C knockdown. In addition, the activation of STAT3 signaling by hypoxia was suppressed by JMJD1C silencing both in vivo and in vitro. The overexpression of STAT3 reversed the inhibitory effect of JMJD1C depletion on proliferation and glycolysis in PASMCs under hypoxia. Thus, JMJD1C induces glycolytic processes by activating STAT3 signaling to promote PASMC proliferation and pulmonary vascular remodeling, suggesting the potential role of JMJD1C in regulating the metabolic program and vascular remodeling in PAH.

Role of HOXA9 in solid tumors: mechanistic insights and therapeutic potential

HOXA9 functioning as a transcription factor is one of the members of HOX gene family, which governs multiple cellular activities by facilitating cellular signal transduction. In addition to be a driver in AML which has been widely studied, the role of HOXA9 in solid tumor progression has also received increasing attention in recent years, where the aberrant expression of HOXA9 is closely associated with the prognosis of patient. This review details the signaling pathways, binding partners, post-transcriptional regulation of HOXA9, and possible inhibitors of HOXA9 in solid tumors, which provides a reference basis for further study on the role of HOXA9 in solid tumors.

A toolbox for class I HDACs reveals isoform specific roles in gene regulation and protein acetylation

The class I histone deacetylases are essential regulators of cell fate decisions in health and disease. While pan- and class-specific HDAC inhibitors are available, these drugs do not allow a comprehensive understanding of individual HDAC function, or the therapeutic potential of isoform-specific targeting. To systematically compare the impact of individual catalytic functions of HDAC1, HDAC2 and HDAC3, we generated human HAP1 cell lines expressing catalytically inactive HDAC enzymes. Using this genetic toolbox we compare the effect of individual HDAC inhibition with the effects of class I specific inhibitors on cell viability, protein acetylation and gene expression. Individual inactivation of HDAC1 or HDAC2 has only mild effects on cell viability, while HDAC3 inactivation or loss results in DNA damage and apoptosis. Inactivation of HDAC1/HDAC2 led to increased acetylation of components of the COREST co-repressor complex, reduced deacetylase activity associated with this complex and derepression of neuronal genes. HDAC3 controls the acetylation of nuclear hormone receptor associated proteins and the expression of nuclear hormone receptor regulated genes. Acetylation of specific histone acetyltransferases and HDACs is sensitive to inactivation of HDAC1/HDAC2. Over a wide range of assays, we determined that in particular HDAC1 or HDAC2 catalytic inactivation mimics class I specific HDAC inhibitors. Importantly, we further demonstrate that catalytic inactivation of HDAC1 or HDAC2 sensitizes cells to specific cancer drugs. In summary, our systematic study revealed isoform-specific roles of HDAC1/2/3 catalytic functions. We suggest that targeted genetic inactivation of particular isoforms effectively mimics pharmacological HDAC inhibition allowing the identification of relevant HDACs as targets for therapeutic intervention.

The Cross Marks the Spot: The Emerging Role of JmjC Domain-Containing Proteins in Myeloid Malignancies

Histone methylation tightly regulates chromatin accessibility, transcription, proliferation, and cell differentiation, and its perturbation contributes to oncogenic reprogramming of cells. In particular, many myeloid malignancies show evidence of epigenetic dysregulation. Jumonji C (JmjC) domain-containing proteins comprise a large and diverse group of histone demethylases (KDMs), which remove methyl groups from lysines in histone tails and other proteins. Cumulating evidence suggests an emerging role for these demethylases in myeloid malignancies, rendering them attractive targets for drug interventions. In this review, we summarize the known functions of Jumonji C (JmjC) domain-containing proteins in myeloid malignancies. We highlight challenges in understanding the context-dependent mechanisms of these proteins and explore potential future pharmacological targeting.

JMJD1C knockdown affects myeloid cell lines proliferation, viability, and gemcitabine/carboplatin-sensitivity

OBJECTIVES

Chemotherapy-induced hematological toxicities are potentially life-threatening adverse drug reactions that vary between individuals. Recently, JMJD1C has been associated with gemcitabine/carboplatin-induced thrombocytopenia in non-small-cell lung cancer patients, making it a candidate marker for predicting the risk of toxicity. This study investigates if JMJD1C knockdown affects gemcitabine/carboplatin-sensitivity in cell lines.

METHODS

Lentiviral transduction-mediated shRNA knockdown of JMJD1C in the cell lines K562 and MEG-01 were performed using shRNA#32 and shRNA#33. The knockdown was evaluated using qPCR. Cell proliferation, viability, and gemcitabine/carboplatin-sensitivity were subsequently determined using cell counts, trypan blue, and the MTT assay.

RESULTS

ShRNA#33 resulted in JMJD1C downregulation by 56.24% in K562 and 68.10% in MEG-01. Despite incomplete knockdown, proliferation (reduction of cell numbers by 61-68%, day 7 post-transduction) and viability (reduction by 21-53%, day 7 post-transduction) were impaired in K562 and MEG-01 cells. Moreover, JMJD1C knockdown reduced the gemcitabine IC50-value for K562 cells (P < 0.01) and MEG-01 cells (P < 0.05) compared to scrambled shRNA control transduced cells.

CONCLUSIONS

Our results suggest that JMJD1C is essential for proliferation, survival, and viability of K562 and MEG-01 cells. Further, JMJD1C also potentially affects the cells gemcitabine/carboplatin-sensitivity. Although further research is required, the findings show that JMJD1C could have an influential role for gemcitabine/carboplatin-sensitivity.

Histone demethylase JMJD1C promotes the polarization of M1 macrophages to prevent glioma by upregulating miR-302a

Glioma is regarded as an aggressive lethal primary brain tumor. Jumonji domain containing 1C (JMJD1C) is a H3K9 demethylase which participates in the progression of various tumors, but its specific function and underlying mechanism in glioma development remain undefined, which is the purpose of our work. We initially assessed JMJD1C expression in glioma tissues and cells using the assays of RT-qPCR and immunohistochemistry. Meanwhile, the H3K9 level at the microRNA (miR)-302a promoter region was measured by chromatin immunoprecipitation assay, while luciferase-based reporter assay was performed for validation of the binding affinity between miR-302a and methyltransferase-like 3 (METTL3). The effect of METTL3 on suppressor of cytokine signaling 2 (SOCS2) was subsequently analyzed by MeRIP-RT-qPCR. Finally, a xenograft tumor model was established in nude mice, followed by measurement of tumor-associated macrophages using flow cytometry. JMJD1C was poorly expressed in glioma tissues. Furthermore, JMJD1C increased miR-302a expression through promoting H3K9me1 demethylation at the miR-302a promoter region. miR-302a was identified to target METTL3, which could inhibit SOCS2 expression via m6A modification. JMJD1C promoted M1 macrophage polarization and suppressed the growth of glioma xenografts through the miR-302a/METTL3/SOCS2 axis both in vivo and in vitro. In conclusion, JMJD1C could enhance M1 macrophage polarization to inhibit the onset of glioma, bringing a new insight into the contribution of JMJD1C to the pathobiology of glioma, with possible implications for targeted therapeutic method.

Transcription analysis of a histones modifiers panel coupled with critical tumor suppressor genes displayed frequent changes in patients with AML.: mRNA levels of histones modifiers and TSGs in AML

Epigenetic alterations could cause leukemia through the activation of normally silent loci or silencing of normally active loci. We herein aimed to compare the expression patterns of a histone modifiers panel consisted of SUV39H1, PRDM16, UHRF2, KDM2B, and KDM3C between acute myeloid leukemia(AML) cells and normal cells and to assess the correlation of these genes with the expression of vital tumor suppressor genes, including p16^INK4A and p53. Bone marrow or peripheral blood samples of 50 AML patients at diagnosis and also 18 subjects with a normal hematopoietic system as a control group were obtained after informed consent. Then, qRT-PCR was performed to determine the expression levels of the aforementioned genes. We found a broad alteration in the expression signature of five out of seven studied genes in AML patients as compared with the control group. UHRF2 and p53 were remarkably downregulated in AML patients (P<0.001), while SUV39H1, PRDM16, and KDM3C were significantly overexpressed (P<0.01). Based on the Spearman rank correlation, SUV39H1 and KDM2B negatively regulated both p16^INK4A and p53 expression. Taken together, our findings provided preliminary evidence regarding the pervasive mRNA perturbation of histone modifiers and their plausible influences on critical tumor suppressor genes. Future studies in this area would be required to assist in establishing these results in the clinical practice of AML patients.

Histone lysine demethylases and their functions in cancer

Histone lysine demethylases (KDMs) are enzymes that remove the methylation marks on lysines in nucleosomes' histone tails. These changes in methylation marks regulate gene transcription during both development and malignant transformation. Depending on which lysine residue is targeted, the effect of a given KDM on gene transcription can be either activating or repressing, and KDMs can regulate the expression of both oncogenes and tumour suppressors. Thus, the functions of KDMs can be regarded as both oncogenic and tumour suppressive, contingent on cell context and the enzyme isoform. Finally, KDMs also demethylate nonhistone proteins and have a variety of demethylase-independent functions. These epigenetic and other mechanisms that KDMs control make them important regulators of malignant tumours. Here, we present an overview of eight KDM subfamilies, their most-studied lysine targets and selected recent data on their roles in cancer stem cells, tumour aggressiveness and drug tolerance.

Evaluation of the Anticancer Activity of pH-Sensitive Polyketal Nanoparticles for Acute Myeloid Leukemia

Polyketals are a class of acid-responsive polymers that have been relatively less explored for drug delivery applications compared to polyesters. The degradation of these polymers is accelerated in an acidic medium and does not result in acidic byproducts. Their biocompatibility depends on the diol used for the synthesis. The present work aims to synthesize, characterize, and fabricate nanospheres of an aliphatic polyketal for delivery of the nucleotide analogue cytarabine toward the treatment of acute myeloid leukemia (AML). The internalization mechanism of the nanospheres was probed, and its implication on the nuclear localization and escape from the endo-lysosomal compartments were studied. The drug-loaded polyketal nanoparticles reduced the cell viability to a greater extent compared with the free drug. The effect of the drug-loaded polyketal nanoparticles on the differential gene expression of leukemic cells was investigated for the first time to understand their therapeutic implications. It was found that treatment with drug-loaded polyketal nanoparticles downregulated AML-specific genes involved in cell proliferation and recurrence compared to the free drug. The protein expression studies were performed for selected genes obtained from gene expression analysis. Biodistribution studies showed that the poly(cyclohexane-1,4-diyl acetone dimethylene ketal) (PCADK) nanoparticles exhibit prolonged circulation time. Overall, our results suggest that polyketal-based delivery of cytarabine represents a more effective alternative strategy for AML therapy.

The JmjC-domain protein NO66/RIOX-1 affects the balance between proliferation and maturation in acute myeloid leukemia

As epigenetic regulators are frequently dysregulated in acute myeloid leukemia (AML) we determined expression levels of the JmjC-protein NO66 in AML cell lines and sub fractions of healthy human hematopoietic cells. NO66 is absent in the AML cell lines KG1/KG1a which consist of cells with the immature CD34⁺/CD38^- phenotype and is regarded as a "stem cell-like" model system. Similarly, NO66 is not detectable in CD34⁺/CD38^- cells purified from healthy donors but is clearly expressed in the more committed CD34⁺/CD38⁺ cell population. Loss of NO66 expression in KG1/KG1a cells is due to hyper-methylation of its promoter and is released by DNA-methyltransferase inhibitors. In KG1a cells stably expressing exogenous wild type (KG1a66wt) or enzymatically inactive mutant (KG1a66mut) NO66, respectively, the wild type protein inhibited proliferation and rDNA transcription. Gene expression profiling revealed that the expression of NO66 induces a transcriptional program enriched for genes with roles in proliferation and maturation (e.g.EPDR1, FCER1A, CD247, MYCN, SNORD13). Genes important for the maintenance of stem cell properties are downregulated (e.g. SIRPA, Lin28B, JAML). Our results indicate that NO66 induces lineage commitment towards myeloid progenitor cell fate and suggest that NO66 contributes to loss of stem cell properties.

Finding underlying genetic mechanisms of two patients with autism spectrum disorder carrying familial apparently balanced chromosomal translocations

BACKGROUND

Genetic etiologies of autism spectrum disorders (ASD) are complex, and the genetic factors identified so far are very diverse. In complex genetic diseases such as ASD, de novo or inherited chromosomal abnormalities are valuable findings for researchers with respect to identifying the underlying genetic risk factors. With gene mapping studies on these chromosomal abnormalities, dozens of genes have been associated with ASD and other neurodevelopmental genetic diseases. In the present study, we aimed to idenitfy the causative genetic factors in patients with ASD who have an apparently balanced chromosomal translocation in their karyotypes.

METHODS

For mapping the broken genes as a result of chromosomal translocations, we performed whole genome DNA sequencing. Chromosomal breakpoints and large DNA copy number variations (CNV) were determined after genome alignment. Identified CNVs and single nucleotide variations (SNV) were evaluated with VCF-BED intersect and Gemini tools, respectively. A targeted resequencing approach was performed on the JMJD1C gene in all of the ASD cohorts (220 patients). For molecular modeling, we used a homology modeling approach via the SWISS-MODEL.

RESULTS

We found that there was no contribution of the broken genes or regulator DNA sequences to ASD, whereas the SNVs on the JMJD1C, CNKSR2 and DDX11 genes were the most convincing genetic risk factors for underlying ASD phenotypes.

CONCLUSIONS

Genetic etiologies of ASD should be analyzed comprehensively by taking into account of the all chromosomal structural abnormalities and de novo or inherited CNV/SNVs with all possible inheritance patterns.

White adipose remodeling during browning in mice involves YBX1 to drive thermogenic commitment

Objective

Increasing adaptive thermogenesis by stimulating browning in white adipose tissue is a promising method of improving metabolic health. However, the molecular mechanisms underlying this transition remain elusive. Our study examined the molecular determinants driving the differentiation of precursor cells into thermogenic adipocytes.

Methods

In this study, we conducted temporal high-resolution proteomic analysis of subcutaneous white adipose tissue (scWAT) after cold exposure in mice. This was followed by loss- and gain-of-function experiments using siRNA-mediated knockdown and CRISPRa-mediated induction of gene expression, respectively, to evaluate the function of the transcriptional regulator Y box-binding protein 1 (YBX1) during adipogenesis of brown pre-adipocytes and mesenchymal stem cells. Transcriptomic analysis of mesenchymal stem cells following induction of endogenous Ybx1 expression was conducted to elucidate transcriptomic events controlled by YBX1 during adipogenesis.

Results

Our proteomics analysis uncovered 509 proteins differentially regulated by cold in a time-dependent manner. Overall, 44 transcriptional regulators were acutely upregulated following cold exposure, among which included the cold-shock domain containing protein YBX1, peaking after 24 h. Cold-induced upregulation of YBX1 also occurred in brown adipose tissue, but not in visceral white adipose tissue, suggesting a role of YBX1 in thermogenesis. This role was confirmed by Ybx1 knockdown in brown and brite preadipocytes, which significantly impaired their thermogenic potential. Conversely, inducing Ybx1 expression in mesenchymal stem cells during adipogenesis promoted browning concurrent with an increased expression of thermogenic markers and enhanced mitochondrial respiration. At a molecular level, our transcriptomic analysis showed that YBX1 regulates a subset of genes, including the histone H3K9 demethylase Jmjd1c, to promote thermogenic adipocyte differentiation.

Conclusion

Our study mapped the dynamic proteomic changes of murine scWAT during browning and identified YBX1 as a novel factor coordinating the genomic mechanisms by which preadipocytes commit to brite/beige lineage.

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Dynamic proteome remodeling occurs in mouse subcutaneous white fat with cold.

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YBX1 acutely increases in response to cold in thermogenic adipose tissues.

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YBX1 is required for the optimal implementation of the early thermogenic program.

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YBX1 promotes metabolic and thermogenic programs and enhances mitochondrial respiration.

An Improved Protocol for Establishment of AML Patient-Derived Xenograft Models

Patient-derived xenografts (PDXs) are the most valuable tool for preclinical drug testing because they retain the genetic diversity and phenotypic heterogeneity of the original tumor. Acute myeloid leukemia (AML) remains difficult to engraft in immunodeficient mice. This is particularly true for long-term frozen patient specimens. This protocol is designed to establish PDXs of human AML with improved engraftment rates. The optimized approach increases the viability of patient cells before implantation, efficiently monitors in vivo engraftment, and maximizes bone marrow collection.

For complete details on the use and execution of this protocol, please refer to Salik et al. (2020) and Lynch et al. (2019).

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This protocol describes the establishment of AML patient-derived xenograft mouse models

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Increased viability of injected cells is critical for high engraftment rate in mice

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Effective collection of bone marrow is a key step in the process of PDX establishment

A chromatin perspective on metabolic and genotoxic impacts on hematopoietic stem and progenitor cells

Fate determination in self-renewal and differentiation of hematopoietic stem and progenitor cells (HSCs and HPCs) is ultimately controlled by gene expression, which is profoundly influenced by the global and local chromatin state. Cellular metabolism directly influences the chromatin state through the dynamic regulation of the enzymatic activities that modify DNA and histones, but also generates genotoxic metabolites that can damage DNA and thus pose threat to the genome integrity. On the other hand, mechanisms modulating the chromatin state impact metabolism by regulating the expression and activities of key metabolic enzymes. Moreover, through regulating either DNA damage response directly or expression of genes involved in this process, chromatin modulators play active and crucial roles in guarding the genome integrity, breaching of which results in defective HSPC function. Therefore, HSPC function is regulated by the dynamic and two-way interactions between metabolism and chromatin. Here, we review recent advances that provide a chromatin perspective on the major impacts the metabolic and genotoxic factors can have on HSPC function and fate determination.

Functional interrogation of HOXA9 regulome in MLLr leukemia via reporter-based CRISPR/Cas9 screen

Aberrant HOXA9 expression is a hallmark of most aggressive acute leukemias, notably those with KMT2A (MLL) gene rearrangements. HOXA9 overexpression not only predicts poor diagnosis and outcome but also plays a critical role in leukemia transformation and maintenance. However, our current understanding of HOXA9 regulation in leukemia is limited, hindering development of therapeutic strategies. Here, we generated the HOXA9-mCherry knock-in reporter cell lines to dissect HOXA9 regulation. By utilizing the reporter and CRISPR/Cas9 screens, we identified transcription factors controlling HOXA9 expression, including a novel regulator, USF2, whose depletion significantly down-regulated HOXA9 expression and impaired MLLr leukemia cell proliferation. Ectopic expression of Hoxa9 rescued impaired leukemia cell proliferation upon USF2 loss. Cut and Run analysis revealed the direct occupancy of USF2 at HOXA9 promoter in MLLr leukemia cells. Collectively, the HOXA9 reporter facilitated the functional interrogation of the HOXA9 regulome and has advanced our understanding of the molecular regulation network in HOXA9-driven leukemia.

Novel therapeutic strategies for MLL-rearranged leukemias

MLL rearrangement is one of the key drivers and generally regarded as an independent poor prognostic marker in acute leukemias. The standard of care for MLL-rearranged (MLL-r) leukemias has remained largely unchanged for the past 50 years despite unsatisfying clinical outcomes, so there is an urgent need for novel therapeutic strategies. An increasing body of evidence demonstrates that a vast number of epigenetic regulators are directly or indirectly involved in MLL-r leukemia, and they are responsible for supporting the aberrant gene expression program mediated by MLL-fusions. Unlike genetic mutations, epigenetic modifications can be reversed by pharmacologic targeting of the responsible epigenetic regulators. This leads to significant interest in developing epigenetic therapies for MLL-r leukemia. Intriguingly, many of the epigenetic enzymes also involve in DNA damage response (DDR), which can be potential targets for synthetic lethality-induced therapies. In this review, we will summarize some of the recent advances in the development of epigenetic and DDR therapeutics by targeting epigenetic regulators or protein complexes that mediate MLL-r leukemia gene expression program and key players in DDR that safeguard essential genome integrity. The rationale and molecular mechanisms underpinning the therapeutic effects will also be discussed with a focus on how these treatments can disrupt MLL-fusion mediated transcriptional programs and impair DDR, which may help overcome treatment resistance.

Targeting RSPO3-LGR4 Signaling for Leukemia Stem Cell Eradication in Acute Myeloid Leukemia

Signals driving aberrant self-renewal in the heterogeneous leukemia stem cell (LSC) pool determine aggressiveness of acute myeloid leukemia (AML). We report that a positive modulator of canonical WNT signaling pathway, RSPO-LGR4, upregulates key self-renewal genes and is essential for LSC self-renewal in a subset of AML. RSPO2/3 serve as stem cell growth factors to block differentiation and promote proliferation of primary AML patient blasts. RSPO receptor, LGR4, is epigenetically upregulated and works through cooperation with HOXA9, a poor prognostic predictor. Blocking the RSPO3-LGR4 interaction by clinical-grade anti-RSPO3 antibody (OMP-131R10/rosmantuzumab) impairs self-renewal and induces differentiation in AML patient-derived xenografts but does not affect normal hematopoietic stem cells, providing a therapeutic opportunity for HOXA9-dependent leukemia.

Crucial Functions of the JMJD1/KDM3 Epigenetic Regulators in Cancer

Epigenetic changes are one underlying cause for cancer development and often due to dysregulation of enzymes modifying DNA or histones. Most Jumonji C domain-containing (JMJD) proteins are histone lysine demethylases (KDM) and therefore epigenetic regulators. One JMJD subfamily consists of JMJD1A/KDM3A, JMJD1B/KDM3B, and JMJD1C/KDM3C that are roughly 50% identical at the amino acid level. All three JMJD1 proteins are capable of removing dimethyl and monomethyl marks from lysine 9 on histone H3 and might also demethylate histone H4 on arginine 3 and nonhistone proteins. Analysis of knockout mice revealed critical roles for JMJD1 proteins in fertility, obesity, metabolic syndrome, and heart disease. Importantly, a plethora of studies demonstrated that especially JMJD1A and JMJD1C are overexpressed in various tumors, stimulate cancer cell proliferation and invasion, and facilitate efficient tumor growth. However, JMJD1A may also inhibit the formation of germ cell tumors. Likewise, JMJD1B appears to be a tumor suppressor in acute myeloid leukemia, but a tumor promoter in other cancers. Notably, by reducing methylation levels on histone H3 lysine 9, JMJD1 proteins can profoundly alter the transcriptome and thereby affect tumorigenesis, including through upregulating oncogenes such as CCND1, JUN, and MYC This epigenetic activity of JMJD1 proteins is sensitive to heavy metals, oncometabolites, oxygen, and reactive oxygen species, whose levels are frequently altered within cancer cells. In conclusion, inhibition of JMJD1 enzymatic activity through small molecules is predicted to be beneficial in many different cancers, but not in the few malignancies where JMJD1 proteins apparently exert tumor-suppressive functions.

The Histone Demethylase JMJD1C Regulates CAMKK2-AMPK Signaling to Participate in Cardiac Hypertrophy

The roles of the histone demethylase JMJD1C in cardiac hypertrophy remain unknown. JMJD1C was overexpressed in hypertrophic hearts of humans and mice, whereas the histone methylation was reduced. Jmjd1c knockdown repressed the angiotensin II (Ang II)-mediated increase in cardiomyocyte size and overexpression of hypertrophic genes in cardiomyocytes. By contrast, JMJD1C overexpression promoted the hypertrophic response of cardiomyocytes. Our further molecular mechanism study revealed that JMJD1C regulated AMP-dependent kinase (AMPK) in cardiomyocytes. JMJD1C did not influence LKB1 but repressed Camkk2 expression in cardiomyocytes. Inhibition of CAMKK2 with STO609 blocked the effects of JMJD1C on AMPK. AMPK knockdown blocked the inhibitory functions of JMJD1C knockdown on Ang II-induced hypertrophic response, whereas metformin reduced the functions of JMJD1C and repressed the hypertrophic response in cardiomyocytes.

The Induction of a Permissive Environment to Promote T Cell Immune Evasion in Acute Myeloid Leukemia: The Metabolic Perspective

Acute myeloid leukemia (AML) is the acute leukemia with highest incidence amongst adults. Despite significant improvements in understanding the genomic landscape and the introduction of novel drugs, long-term outcome remains unsatisfactory. Recently, immunotherapeutic approaches have heralded a new era in cancer treatment. The success of allogeneic hematopoietic stem cell transplantation in AML highlights the disease's immunoresponsiveness. Several immunotherapeutic applications are currently under clinical evaluation and include immune checkpoint blockades, T cell-engaging antibodies, and genetically engineered T cells. However, immunoevasive mechanisms employed by AML blasts severely hamper our endeavors. A better understanding of the underlying mechanisms remains a prerequisite for improving treatment efficacy. One of the hallmarks of the cancer cells is metabolic reprogramming, introduced by Otto Warburg's seminal studies during the beginnings of the last century. Nowadays, it is well established that metabolic adaptation is not just an epiphenomenon during oncogenesis but rather a necessity for tumor development and progression. Furthermore, accumulating data suggest an important role of aberrant tumor cell metabolism for immune escape. AML blasts display a number of metabolic alterations that could be linked to immunoregulation, and these include competition over substrates, abundant release of bioactive metabolites, and an overall microenvironmental metabolic re-modeling that favors the induction or survival of immunoregulatory cell subsets such as regulatory T cells. In this review, we outline the immunoevasive character of the AML blasts' bioenergetics, set it into context with oncogenic mutations, and discuss potentially suitable countermeasures and their limitations.

MicroRNA-186-5p Inhibits Proliferation And Metastasis Of Esophageal Cancer By Mediating HOXA9

Objective

MicroRNA (miRNA) is an endogenous, non-coding small RNA that plays a key role in regulating organism biology and pathology. The aim of this study was to investigate the expression characteristics of microRNA-186-5p in esophageal cancer (ECa) and its correlation with clinical progression and prognosis, and to further explore its underlying mechanisms.

Methods

Real-time quantitative PCR (qRT-PCR) was used to detect microRNA-186-5p level in 45 pairs of ECa tissue samples and adjacent ones, and to analyze the expression of microRNA-186-5p and clinical progression of ECa and prognosis. The relationship between microRNA-186-5p level in ECa cell lines was further verified by qRT-PCR. Finally, the potential mechanism was explored using luciferase reporter gene assay and cell recovery experiment.

Results

QRT-PCR results revealed that the expression of microRNA-186-5p in ECa tissues was remarkably lower than that in adjacent tissues, and the difference was statistically significant. Compared with patients with high expression of microRNA-186-5p, patients with low expression of microRNA-186-5p had higher incidence of pathological stage and lower overall survival rate. Besides, compared with the miR-NC group, the microRNA-186-5p mimics group had a significant decrease in proliferation and metastasis ability of ECa cells. Subsequent qRT-PCR validation in ECa cell lines and tissues indicated a significant increase in HOXA9 expression and a negative correlation with microRNA-186-5p.

Conclusion

The expression of microRNA-186-5p was remarkably decreased in ECa, which was remarkably correlated with pathological stage, distant metastasis and poor prognosis of ECa. The results suggested that microRNA-186-5p may inhibit cell proliferation of ECa by regulating HOXA9.

Small molecular modulators of JMJD1C preferentially inhibit growth of leukemia cells

Histone demethylases are promising therapeutic targets as they play fundamental roles for survival of Mixed lineage leukemia rearranged acute leukemia (MLLr AL). Here we focused on the catalytic Jumonji domain of histone H3 lysine 9 (H3K9) demethylase JMJD1C to screen for potential small molecular modulators from 149,519 natural products and 33,765 Chinese medicine components via virtual screening. JMJD1C Jumonji domain inhibitor 4 (JDI-4) and JDI-12 that share a common structural backbone were detected within the top 15 compounds. Surface plasmon resonance analysis showed that JDI-4 and JDI-12 bind to JMJD1C and its family homolog KDM3B with modest affinity. In vitro demethylation assays showed that JDI-4 can reverse the H3K9 demethylation conferred by KDM3B. In vivo demethylation assays indicated that JDI-4 and JDI-12 could induce the global increase of H3K9 methylation. Cell proliferation and colony formation assays documented that JDI-4 and JDI-12 kill MLLr AL and other malignant hematopoietic cells, but not leukemia cells resistant to JMJD1C depletion or cord blood cells. Furthermore, JDI-16, among multiple compounds structurally akin to JDI-4/JDI-12, exhibits superior killing activities against malignant hematopoietic cells compared to JDI-4/JDI-12. Mechanistically, JDI-16 not only induces apoptosis but also differentiation of MLLr AL cells. RNA sequencing and quantitative PCR showed that JDI-16 induced gene expression associated with cell metabolism; targeted metabolomics revealed that JDI-16 downregulates lactic acids, NADP⁺ and other metabolites. Moreover, JDI-16 collaborates with all-trans retinoic acid to repress MLLr AML cells. In summary, we identified bona fide JMJD1C inhibitors that induce preferential death of MLLr AL cells.