Extrinsic Regulation Research Articles

Nurses’ Work Motivation and their Demographics: Basis for Human Resource Management

This study assessed the level of work motivation of 245 nurses generated through snowball sampling in a tertiary government hospital in Hail City, Kingdom of Saudi Arabia using the Multidimensional Work Motivation Scale. The results indicated that the nurses had a low level of amotivation, moderate levels of all subtypes of extrinsic regulation, and moderate levels of intrinsic regulation leading to an overall moderate level of work motivation. Significant differences in levels of work motivation were observed in the domain of amotivation when nurses were grouped according to work position; in the domain of extrinsic motivation-social when nurses were grouped according to civil status, monthly salary and years of experience in the institution; in the domain of extrinsic motivation-material when nurses were grouped according to years of experience in the institution; in the domain of introjected regulation when the nurses were grouped according to age and civil status; and in the domains of identified regulation and intrinsic motivation when they were grouped according to civil status (p≤0.05). Hospital administrators need to implement specific human resource management strategies such as: (1) the implementation of a fair system of staff performance appraisal through management by objectives; (2) the provision of training needs of staff for learning and career development; (3) mechanisms that foster social support among healthcare teams; (4) mechanisms that promote nurse engagement, autonomy and empowerment; and (5) a consistent and equitable system of rewards and promotions in order to enhance the level of work motivation of nurses.

Metabolic Analysis of Mouse Hematopoietic Stem and Progenitor Cells.

The intrinsic properties of self-renewal and differentiation of hematopoietic stem and progenitor cells (HSPCs) play a critical role in the regeneration of mature hematopoietic cells at steady state and in stress conditions including bleeding, inflammation and aging. Common techniques such as flow cytometry and genetic methods have answered many questions about their intrinsic and extrinsic regulation. Using these approaches, it was demonstrated that HSPCs in the bone marrow demonstrate low rates of proliferation and apoptosis. This dormant phenotype is associated with a low production of reactive oxygen species and low mitochondrial activity.Here, we describe the methodology to characterize the physiologic state of HSPCs isolated from their native hematopoietic organ using flow cytometry-based assays. These protocols allow evaluation of their ROS levels and activated signaling pathways under various conditions.

Genetic dissection of growth trajectories in forest trees: From FunMap to FunGraph.

Growth is the developmental process involving important genetic components. Functional mapping (FunMap) has been used as an approach to map quantitative trait loci (QTLs) governing growth trajectories by incorporating growth equations. FunMap is based on reductionism thinking, with a power to identify a small set of significant QTLs from the whole pool of genome-wide markers. Yet, increasing evidence shows that a complex trait is controlled by all genes the organism may possibly carry. Here, we describe and demonstrate a different mapping approach that encapsulates all markers into genetic interaction networks. This approach, symbolized as FunGraph, combines functional mapping, evolutionary game theory, and prey-predator theory into mathematical graphs, allowing the observed genetic effect of a locus to be decomposed into its independent component (resulting from this locus' intrinsic capacity) and dependent component (due to extrinsic regulation by other loci). Using FunGraph, we can visualize and trace the roadmap of how each locus interact with every other locus to impact growth. In a population-based association study of Euphrates poplar, we use FunGraph to identify the previously neglected genetic interaction effects that contribute to the genetic architecture of juvenile stem growth. FunGraph could open up a novel gateway to comprehend the global genetic control mechanisms of complex traits.

Machine Learning of Hematopoietic Stem Cell Divisions from Paired Daughter Cell Expression Profiles Reveals Effects of Aging on Self-Renewal.

Changes in stem cell activity may underpin aging. However, these changes are not completely understood. Here, we combined single-cell profiling with machine learning and invivo functional studies to explore how hematopoietic stem cell (HSC) divisions patterns evolve with age. We first trained an artificial neural network (ANN) to accurately identify cell types in the hematopoietic hierarchy and predict their age from single-cell gene-expression patterns. We then used this ANN to compare identities of daughter cells immediately after HSC divisions and found that the self-renewal ability of individual HSCs declines with age. Furthermore, while HSC cell divisions are deterministic and intrinsically regulated in young and old age, they are variable and niche sensitive in mid-life. These results indicate that the balance between intrinsic and extrinsic regulation of stem cell activity alters substantially with age and help explain why stem cell numbers increase through life, yet regenerative potency declines.

Mammary epithelial morphogenesis in 3D combinatorial microenvironments

Human mammary epithelial cells can proliferate and reorganize into polarized multi-cellular constructs in-vitro, thereby functioning as an important model system in recapitulating key steps of in-vivo morphogenesis. Current approaches to constructing such three-dimensional mimics of the in-vivo microenvironment have involved the use of complex and ill-defined naturally derived matrices, whose properties are difficult to manipulate independently, and which have therefore limited our ability to understand the extrinsic regulation of morphogenesis. Here, we employ an automated, high-throughput approach to array modular building blocks of synthetic components, and develop a systematic approach to analyze colonies resulting from these varied microenvironmental combinations. This methodology allows us to systematically map the relationship between microenvironmental properties and ensuing morphogenetic phenotypes. Our analysis reveals that apico-basal polarity of mammary epithelial cells occurs within a narrow range of matrix stiffness, and that phenotypic homogeneity is favored in matrices which are insensitive to MMP-mediated degradation. Furthermore, combinations of extracellular proteins in the matrix finely tune the morphology of the mammary colonies, suggesting that subtle disregulations of the microenvironment may play a significant role in pathological disease states. This approach, which leverages the combinatorial possibilities of modular synthetic artificial extracellular matrices with an automated technology platform, demonstrates how morphogenesis can be assessed systematically in 3D, and provides new insights into mammary epithelial multicellularity.

Effects of a teacher training intervention on teachers’ and students’ motivation to physical education class

The present study evaluated the effects of a teacher training intervention, based on Self-Determination Theory, on teachers’ and students’ motivation in physical education class. This is a pre-post quasi-experimental study with 4 physical education teachers and 611 students from four public schools. A handbook was developed and teacher training sessions were conducted. Statistical analysis consisted of paired t-tests and general linear model repeated measures to assess teachers’ self-determined motivation and linear mixed effect regression to evaluate students’ motivation. A significant increase in teachers’ and students’ motivation score was observed after the intervention. Among teacher, we verified an increase in self-determined motivation. Among students there were significant interaction time by group in Extrinsic Motivation Identified Regulation (F=5.6), Extrinsic Motivation External Regulation (F=7.41), Amotivation (F=5.32) and Self-determined Motivation (F=4.87). Also, Intrinsic Motivation significantly declined with age for boys (β= -0.151) and girls (β= -0.121) as well as Extrinsic Motivation Introjected Regulation for girls β= (-0.141). Training sessions can support teachers in planning lessons resulting in increasing teacher and students' motivation in physical education classes. However, this strategy was not enough to improve intrinsic motivation during the investigated period.

A Modern View of the Interstitial Space in Health and Disease.

Increases in the volume of the interstitial space are readily recognized clinically as interstitial edema formation in the loose connective tissue of skin, mucosa, and lung. However, the contents and the hydrostatic pressure of this interstitial fluid can be very difficult to determine even in experimental settings. These difficulties have long obscured what we are beginning to appreciate is a dynamic milieu that is subject to both intrinsic and extrinsic regulation. This review examines current concepts regarding regulation of interstitial volume, pressure, and flow and utilizes that background to address three major topics of interest that impact IV fluid administration. The first of these started with the discovery that excess dietary salt can be stored non-osmotically in the interstitial space with minimal impact on vascular volume and pressures. This led to the hypothesis that, along with the kidney, the interstitial space plays an active role in the long-term regulation of blood pressure. Second, it now appears that hypovolemic shock leads to systemic inflammatory response syndrome principally through the entry of digestive enzymes into the intestinal interstitial space and the subsequent progression of enzymes and inflammatory agents through the mesenteric lymphatic system to the general circulation. Lastly, current evidence strongly supports the non-intuitive view that the primary factor leading to inflammatory edema formation is a decrease in interstitial hydrostatic pressure that dramatically increases microvascular filtration.

Intrinsic and extrinsic regulators of oligodendrocyte progenitor proliferation and differentiation

Oligodendrocytes are highly specialized glial cells, responsible for producing myelin in the central nervous system (CNS). The multi-stage process of oligodendrocyte development is tightly regulated to ensure proper lineage progression of oligodendrocyte progenitor cells (OPCs) to mature myelin producing oligodendrocytes. This developmental process involves complex interactions between several intrinsic signaling pathways that are modulated by an array of extrinsic factors. Understanding these regulatory processes is of crucial importance, as it may help to identify specific molecular targets both to enhance plasticity in the normal CNS and to promote endogenous recovery following injury or disease. This review describes two major regulators that play important functional roles in distinct phases of oligodendrocyte development: OPC proliferation and differentiation. Specifically, we highlight the roles of the extracellular astrocyte/radial glia-derived protein Endothelin-1 in OPC proliferation and the intracellular Akt/mTOR pathway in OPC differentiation. Lastly, we reflect on how recent advances in neuroscience and scientific technology will enable greater understanding into how intrinsic and extrinsic regulators interact to generate oligodendrocyte diversity.

Mitochondria Control Cortical Cell Fate after Mitosis.

During brain development, the daughter cells of neural stem cells have to make a choice - either to become new stem cells or to differentiate into neurons. In a recent issue of Science, Iwata etal. (2020) show that these fate decisions can be determined after mitosis by mitochondrial remodeling.

Regulatory Role of Quiescence in the Biological Function of Cancer Stem Cells.

Quiescence in cancer cells is considered a therapeutic challenge as it confers dormancy in tumour, hence circumventing inherent anti-neoplastic surveillance system and standard-of-care cancer therapeutics including chemotherapy and radiotherapy. Since majority of the therapeutics target actively proliferating cancer cells, cancer cells eventually develop quiescent nature as mechanism of survival and cancer progression under both niche and therapeutic pressures. Quiescence state in cancer cells, eventually, confers resistant and aggressive nature to conventional cancer therapies, resulting in disease progression and relapse. Therefore, targeting quiescent cancer cells or cancer stem cells is a promising therapeutic approach, however an extensive review of the relevant information is needed in order to device an effective therapy. While the evidence of quiescence regulation in CSCs is rather a complex molecular and cellular network, herein, we aim to provide a comprehensive understanding of both intrinsic and extrinsic regulation in association with the function of CSCs. Findings on induction of quiescent state in CSCs population, its regulation at both cellular and molecular level, key molecular regulators, cellular events and processes including potential targets to develop therapeutics are extensively reviewed. This review also highlights the impact of CSC plasticity on quiescence which capturing the key challenge of targeting the cells in this state. Beyond understanding the mechanisms underlying quiescence nature of cancer cells, this review provides insightful perspective and future direction on insight in targeting these populations, hence collapse the tumour dormancy programme in order to eradicate tumour mass as a whole. Capability of CSCs to establish quiescent state as a mechanism of survival during unfavorable conditions, as well as its impact in cancer progression and subsequent relapse, including the potential therapeutic strategy to eradicate this CSCs sub-population in the tumor mass as an effective cancer therapy.

MicroRNA-135a-5p Promotes the Functional Recovery of Spinal Cord Injury by Targeting SP1 and ROCK

Emerging evidence indicates that microRNAs play a pivotal role in neural remodeling after spinal cord injury (SCI). This study aimed to investigate the mechanisms of miR-135a-5p in regulating the functional recovery of SCI by impacting its target genes and downstream signaling. The gene transfection assay and luciferase reporter assay confirmed the target relationship between miR-135a-5p and its target genes (specificity protein 1 [SP1] and Rho-associated kinase [ROCK]1/2). By establishing the H2O2-induced injury model, miR-135a-5p transfection was found to inhibit the apoptosis of PC12 cells by downregulating the SP1 gene, which subsequently induced downregulation of pro-apoptotic proteins (Bax, cleaved caspase-3) and upregulation of anti-apoptotic protein Bcl-2. By measuring the neurite lengths of PC12 cells, miR-135a-5p transfection was found to promote axon outgrowth by downregulating the ROCK1/2 gene, which subsequently caused upregulation of phosphate protein kinase B (AKT) and phosphate glycogen synthase kinase 3β (GSK3β). Use of the rat SCI models showed that miR-135a-5p could increase the Basso, Beattie, and Bresnahan (BBB) scores, indicating neurological function recovery. In conclusion, the miR-135a-5p-SP1-Bax/Bcl-2/caspase-3 and miR-135a-5p-ROCK-AKT/GSK3β axes are involved in functional recovery of SCI by regulating neural apoptosis and axon regeneration, respectively, and thus can be promising effective therapeutic strategies in SCI.

Abstract 5616: Characterization of a spectrum of DTR models for conditional depletion of specific immune cell lineages

Abstract Introduction: Cancer immunotherapy often works through more than one mechanism of action (MOA) mediated by multiple immune cell subsets. We have demonstrated that the antitumor effects of anti-PD-1 treatment, while predominately driven by CD8+ cytotoxic T cells (CTL), is also led by CD4+ effector T cells in some tumors. For anti-CTLA-4 treatment, it is still under debate whether efficacy is attributed to intrinsic CD8+ T cell activation, Treg depletion, or other extrinsic regulations. Other immune modulators have MOAs with even more potential to impact treatment outcomes, and may differ significantly in different tumor microenvironments. It is critical to dissect the MOA of specific treatments by clarifying their role through different immune cell lineages, which may guide on rational approaches for monotherapy as well as combination strategies. Methods: We have developed a series of immune lineage-DTR (diphtheria toxin receptor) transgenic mouse models, in which specific immune cell subsets can be easily depleted from the whole mouse following diphtheria toxin (DT) administration. These transgenic mice were engineered to express DTR-EGFP downstream of specific lineage markers, i.e. CD8a, CD4, FoxP3, Ncr-1, CD19, or CD11c. Therefore, expression of DTR and EGFP were both regulated in the same manner as endogenous lineage markers without disrupting their own expression. We have confirmed EGFP expression on specific immune cell lineages by FACS analysis. To test the depletion efficiency by DT in the mice, we engrafted MC38 tumors into DTR mice or naïve mice, treated the mice with DT, and monitored the depletion of specific immune cell lineages over time in blood, spleen, and tumor infiltrating lymphocytes (TILs). Results: Analysis of depletion efficiency showed that DT administration led to complete depletion of the targeted immune cell populations in blood by Day 2 to Day 6 post DT administration, while repopulation was observed from Day 13 for some lines (e.g. Ncr-1 and CD19). The proportion of the targeted immune cell subset in tumor and spleen remained lower than the naïve mice by study termination on Day 20. The DTR transgene did not affect MC38 tumor growth and the tumor take rate in these mice was 100%. MC38 tumor growth was significantly slower when CD4 and FoxP3 cell populations were depleted. In contrast, CD8 depletion led to a much faster tumor growth rate, whereas NK or B cell depletion appeared not to impact tumor growth. Conclusions: Taken together, immune cell specific DTR models provide important tools for examining the MOA of various cancer immunotherapies. They also benchmark the maximal tumor growth inhibition that can be achieved by manipulating specific immune cell lineages in specific syngeneic tumors. Citation Format: Ying Jin, Jiahua Zhou, Fengge Li, Ruilin Sun, Annie Xiaoyu An, Henry Q. X. Li, Davy Xuesong Ouyang. Characterization of a spectrum of DTR models for conditional depletion of specific immune cell lineages [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5616.

Abstract 694: PAWI-2 overcomes tumor stemness and drug resistance in pancreatic cancer stem cells

Abstract Today, pancreatic cancer (PC) remains a major health problem in the US and soon will be the second most common cause of mortality due to cancer. However, most of the front-line PC chemotherapies cause serious side effects and a majority of patients with PC are often resistant to clinical therapies. The fact that cancer stem cells (CSCs) become enriched after anti-cancer therapy implicates CSCs as key contributors to tumor dormancy, metastasis, and relapse in PC. Given the important role of human pancreatic cancer stem cells (hPCSCs) in PC, development of a novel treatment strategy that targets hPCSCs or their extrinsic and intrinsic regulators could be of great clinical utility to treat PC. Herein, we used a highly validated hPCSCs model (FGβ3 cells) to test a novel compound (PAWI-2) to target CSCs. In this hPCSC model, integrin αvβ3 expression was shown to be a marker/functional contributor to CSC progression and drug resistance attributed to its ability to trigger anchorage-independent cell survival and tumor metastasis. Specifically, integrin αvβ3 recruits KRAS and RalB to tumor cell plasma membranes to activate NF-κB signaling that triggers dysregulated KRAS-RalB-NF-κB pathways. This was shown to be a pharmacological target to reverse CSC-like properties or re-sensitize drug resistance (e.g., EGFR inhibitors, erlotinib) of established FGβ3 tumors. Compared to parental FG cells, PAWI-2 showed greater potency to inhibit cell viability and self-renewal capacity of FGβ3 cells. PAWI-2 inhibited dysregulated integrin β3-KRAS-RalB-NF-κB signaling independent of KRAS and Ral. This is clinically relevant because >90% of KRAS is activated by mutations in PC and RAS or Ral inhibitors have not proven effective clinically. PAWI-2 targeted downstream of KRAS signaling and was negatively regulated by other feedback mechanisms. This was further shown by genetic knockdown of key regulator and co-treatment of specific inhibitors. PAWI-2 overcomes erlotinib resistance in FGβ3 cells with greater potency than bortezomib. In the proposed mechanism of PAWI-2 action, key regulators link the inhibition of KRAS signaling and cell cycle arrest (G2/M). The great utility and pharmacological potency of PAWI-2 in FGβ3 cells (that possess stem-like properties) compared to FG cells provide a basis for further development. PAWI-2 as an efficient therapeutic to reverse tumor stemness and resensitize CSC tumors to drug inhibition. This work was supported by Inception Award from California Institute for Regenerative Medicine (CIRM) (DISC1-10583; J.R. Cashman) and by funds from the Human BioMolecular Research Institute. Citation Format: Jiongjia Cheng, John Cashman, Jorge Gomez-Galeno. PAWI-2 overcomes tumor stemness and drug resistance in pancreatic cancer stem cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 694.

Multispecies RNA tomography reveals regulators of hematopoietic stem cell birth in the embryonic aorta

AbstractThe defined location of a stem cell within a niche regulates its fate, behavior, and molecular identity via a complex extrinsic regulation that is far from being fully elucidated. To explore the molecular characteristics and key components of the aortic microenvironment, where the first hematopoietic stem cells are generated during development, we performed genome-wide RNA tomography sequencing on zebrafish, chicken, mouse, and human embryos. The resulting anterior-posterior and dorsal-ventral transcriptional maps provided a powerful resource for exploring genes and regulatory pathways active in the aortic microenvironment. By performing interspecies comparative RNA sequencing analyses and functional assays, we explored the complexity of the aortic microenvironment landscape and the fine-tuning of various factors interacting to control hematopoietic stem cell generation, both in time and space in vivo, including the ligand-receptor couple ADM-RAMP2 and SVEP1. Understanding the regulatory function of the local environment will pave the way for improved stem cell production in vitro and clinical cell therapy.

Stem Cells of the Aging Brain.

The adult central nervous system (CNS) contains resident stem cells within specific niches that maintain a self-renewal and proliferative capacity to generate new neurons, astrocytes, and oligodendrocytes throughout adulthood. Physiological aging is associated with a progressive loss of function and a decline in the self-renewal and regenerative capacities of CNS stem cells. Also, the biggest risk factor for neurodegenerative diseases is age, and current in vivo and in vitro models of neurodegenerative diseases rarely consider this. Therefore, combining both aging research and appropriate interrogation of animal disease models towards the understanding of the disease and age-related stem cell failure is imperative to the discovery of new therapies. This review article will highlight the main intrinsic and extrinsic regulators of neural stem cell (NSC) aging and discuss how these factors impact normal homeostatic functions within the adult brain. We will consider established in vivo animal and in vitro human disease model systems, and then discuss the current and future trajectories of novel senotherapeutics that target aging NSCs to ameliorate brain disease.

3020 – THE CLONAL AND MOLECULAR AETIOLOGY OF EMERGENCY DENDRITIC CELL DEVELOPMENT

Extrinsic regulation of single haematopoietic stem and progenitor cell (HSPC) fate is crucial for immune cell development. Here, we examine the aetiology of Flt3 ligand (Flt3L)-mediated emergency development of type 1 conventional dendritic cells (cDC1s), which results in enhanced immunity against infections and cancer. Using cellular barcoding, we demonstrate a predominant role of enhanced clonal expansion and moderate contribution via recruitment of additional cDC1-generating HSPCs. The selective cDC1 expansion occurs primarily via multi-/oligo-potent clones, without compromising output to other lineages. To understand the molecular hallmarks early during a Flt3L response, we develop Divi-Seq to simultaneously profile cell division history, surface phenotype and transcriptional state of single HSPCs. We discover that Flt3L-responsive HSPCs maintain a proliferative ‘early progenitor'-like state, which leads to selective emergence of CD11c+cKit+ transitional precursors with high cellular output to cDC1s. These findings inform the mechanistic action of Flt3L in natural immunity and immunotherapy at a clonal level.

1005 – REGULATION OF HEMATOPOIETIC STEM CELL BIRTH IN THE EMBRYONIC AORTA

In vertebrates, hematopoietic stem cell (HSC) emergence mainly occurs in the dorsal aorta of the embryo. HSCs arise from hemogenic endothelial (HE) cells via an endothelial-to-hematopoietic transition (EHT) and the formation of intra-aortic hematopoietic clusters (IAHCs). The molecular events controlling endothelial specification, EHT and IAHC formation, as it occurs <i>in vivo</i> inside the aorta, are very complex and still poorly understood. The defined location of IAHCs/HSCs within the aortic niche regulates their fate, behaviour, and molecular identity via a complex extrinsic regulation. We made use of genome-wide RNA sequencing and tomography sequencing to explore the molecular characteristics and key components of IAHCs and precursors and the complexity of the aortic microenvironment landscape. Through interspecies comparative RNA sequencing analyses of zebrafish, chicken, mouse, and human embryos, we identified novel conserved processes that control HSC generation and mapped interactions between the niche and IAHCs. Among the various factors interacting to spatiotemporally regulate HSC generation <i>in vivo,</i> we functionally identified the niche-secreted ligand ADM and its IAHCs expressed receptor RAMP2, as well as SVEP1. Next to cell-extrinsic regulators, we also recently highlighted the important role of so far unexplored cytoskeletal rearrangements and microtubule dynamics regulation during EHT, HSC precursor maturation and self-renewal. Understanding the different cellular and molecular aspects that regulate HSC birth <i>in vivo</i> will pave the way for improved HSC production <i>in vitro</i> and clinical cell therapy.

“Calm Down,” “Cheer Up”: How Age Influences the Way We Manage Emotion in Social Partners

This study examines how individuals (regulators) manage emotion in their social partners (targets) and whether the age of the regulator or the age of the target influences extrinsic emotion regulation strategy preference. An online questionnaire was used to assess extrinsic emotion regulation among 580 participants aged 18-87 years (M = 50.04, SD = 18.13). Participants (regulators) indicated the extent to which they would be likely to use different strategies when interacting with a younger or older target who was upset. Results of multi-level modeling showed that older regulators endorsed less use of situation modification than younger regulators, but age differences in regulators' use of other strategies were not significant. After adjustment for relationship-specific covariates, regulators endorsed less use of attentional deployment and cognitive change, for older targets than younger targets. Results are discussed in the context of lifespan perspectives on social behavior and emotion regulation.

Denatonium as a Bitter Taste Receptor Agonist Modifies Transcriptomic Profile and Functions of Acute Myeloid Leukemia Cells.

The contribution of cell-extrinsic factors in Acute Myeloid Leukemia (AML) generation and persistence has gained interest. Bitter taste receptors (TAS2Rs) are G protein-coupled receptors known for their primary role as a central warning signal to induce aversion toward noxious or harmful substances. Nevertheless, the increasing amount of evidence about their extra-oral localization has suggested a wider function in sensing microenvironment, also in cancer settings. In this study, we found that AML cells express functional TAS2Rs. We also highlighted a significant association between the modulation of some TAS2Rs and the poor-prognosis AML groups, i.e., TP53- and TET2-mutated, supporting a potential role of TAS2Rs in AML cell biology. Gene expression profile analysis showed that TAS2R activation with the prototypical agonist, denatonium benzoate, significantly modulated a number of genes involved in relevant AML cellular processes. Functional assay substantiated molecular data and indicated that denatonium reduced AML cell proliferation by inducing cell cycle arrest in G0/G1 phase or induced apoptosis via caspase cascade activation. Moreover, denatonium exposure impaired AML cell motility and migratory capacity, and inhibited cellular respiration by decreasing glucose uptake and oxidative phosphorylation. In conclusion, our results in AML cells expand the observation of cancer TAS2R expression to the setting of hematological neoplasms and shed light on a role of TAS2Rs in the extrinsic regulation of leukemia cell functions.

Epidermal growth factor receptor–dependent DNA repair promotes murine and human hematopoietic regeneration

AbstractChemotherapy and irradiation cause DNA damage to hematopoietic stem cells (HSCs), leading to HSC depletion and dysfunction and the risk of malignant transformation over time. Extrinsic regulation of HSC DNA repair is not well understood, and therapies to augment HSC DNA repair following myelosuppression remain undeveloped. We report that epidermal growth factor receptor (EGFR) regulates DNA repair in HSCs following irradiation via activation of the DNA-dependent protein kinase–catalytic subunit (DNA-PKcs) and nonhomologous end joining (NHEJ). We show that hematopoietic regeneration in vivo following total body irradiation is dependent upon EGFR-mediated repair of DNA damage via activation of DNA-PKcs. Conditional deletion of EGFR in hematopoietic stem and progenitor cells (HSPCs) significantly decreased DNA-PKcs activity following irradiation, causing increased HSC DNA damage and depressed HSC recovery over time. Systemic administration of epidermal growth factor (EGF) promoted HSC DNA repair and rapid hematologic recovery in chemotherapy-treated mice and had no effect on acute myeloid leukemia growth in vivo. Further, EGF treatment drove the recovery of human HSCs capable of multilineage in vivo repopulation following radiation injury. Whole-genome sequencing analysis revealed no increase in coding region mutations in HSPCs from EGF-treated mice, but increased intergenic copy number variant mutations were detected. These studies demonstrate that EGF promotes HSC DNA repair and hematopoietic regeneration in vivo via augmentation of NHEJ. EGF has therapeutic potential to promote human hematopoietic regeneration, and further studies are warranted to assess long-term hematopoietic effects.