Histone modifiers are oxygen sensors.

Hypoxia signals directly to chromatin via histone demethylases to alter gene expression</jats:p

Prognostic models turn the Heat(IT)up on FLT3ITD-mutated AML.

The presence of internal tandem duplications (ITDs) in the FLT3 receptor tyrosine kinase gene have long been known to confer a poor prognosis to acute myeloid leukemia (AML) patients. Now, specific structural features of the ITD are also suggested to alter patient outcome, including sensitivity to targeted therapies, prompting their evaluation in therapeutic algorithms.B.J.P. Huntly is supported by The European Research Council (COMAL: 647685) and Cancer Research UK (A25508). P. Gallipoli is supported by the Wellcome Trust (109967/Z/15/Z) and an ASH Global Research Award

Investigation of the role of autocrine and paracrine growth factors in the survival and proliferation of chronic myeloid leukaemia stem and progenitor cells

Chronic myeloid leukaemia (CML) is a clonal myeloproliferative disorder arising in a haemopoietic stem cell (HSC) as a result of the reciprocal translocation between the long arms of chromosomes 9 and 22 (t9;22), leading to the formation of the fusion oncogene BCR-ABL. BCR-ABL has constitutive tyrosine kinase (TK) activity which drives, at least during the chronic phase (CP) of the disease, myeloid progenitor cells expansion through terminally differentiated cells and is necessary for the transformed phenotype. The introduction at the end of the last century of BCR-ABL TK inhibitors (TKI) has dramatically changed the management of newly diagnosed CP CML patients as the vast majority achieve deep molecular responses while enjoying good quality of life when treated with TKI. However about 20% of patients still show various degree of resistance to all currently available TKI while in those achieving deep responses, there is compelling evidence of persistent minimal residual disease demanding lifelong treatment which has obvious implications in terms of compliance, adverse events and costs. It is now known that the main reason for disease persistence in CML patients treated with TKI lies in the insensitivity of the most primitive CML leukaemia stem cell (LSC). More recent evidence has demonstrated that, in contrast to more mature leukaemic progenitor cells, CML LSC are not addicted to BCR-ABL kinase activity but rather rely on other stem cell intrinsic pathways for their survival. The main focus in the CML field is therefore to identify these pathways while also trying to exploit them therapeutically to achieve CML LSC eradication and as a result disease cure. Growth factor (GF) signals are known to provide survival cues to CML stem and progenitor cells (SPC) and potentially support their survival even in the presence of TKI. Moreover CML SPC are also known to produce higher levels of some GFs via an autocrine loop and support their survival and proliferation through this mechanism. In this thesis, the characterisation of the autocrine GF production by CML SPC was extended while also investigating the role of several GFs and downstream signals in survival, proliferation and self-renewal of CML SPC. Whenever possible, the consequences of therapeutic targeting of these signals on CML SPC survival and proliferation were also assessed in vitro. In particular the role of the intracellular janus kinase (JAK) 2, which relays several myeloid GF signals, such as those from interleukin (IL)-3 and granulocyte macrophage colony-stimulating factor (GM-CSF), in CML SPC survival and proliferation was investigated mainly because higher levels of autocrine expression of GM-CSF by CML SPC relative to normal were demonstrated, while autocrine IL-3 production by CML SPC had already been shown. Moreover the cognate receptor of both GM-CSF and IL-3 (CSF2RB) was also shown to be expressed at higher levels in CML SPC relative to their normal counterparts, further supporting investigations on the role of JAK2 in CML SPC biology. Indeed targeting JAK2 with small molecule inhibitors in CML SPC in vitro, particularly in the presence of maximal BCR-ABL TK inhibition, resulted in increased apoptosis, reduced proliferation and colony output of CML SPC. The JAK2 inhibitor plus TKI combination treatment, compared to either single agent, further reduced survival of the more primitive quiescent LSCs in vitro, while also reducing engraftment of primary CML CD34+ cells in vivo in immunocompromised hosts. Although a degree of toxicity to normal haemopoietic stem and progenitor cells (HSPC) was observed, this was not as great as seen in CML SPC, thus suggesting that a therapeutic window for using JAK2 inhibitors in CML patients might be present when a carefully selected concentration of these compounds is chosen. Tumour necrosis factor (TNF)-α was another GF shown to be produced in an autocrine fashion at higher levels by CML SPC relative to normal HSPC. Moreover its levels of production by CML SPC were not modulated by BCR-ABL TK activity. Using a small molecule TNF-α inhibitor and exogenous TNF-α, it was shown that autocrine TNF-α acts as a survival and proliferative signal in CML SPC. Moreover its role became even more important in the presence of TKI, as combining TNF-α inhibition with TKI led to high levels of apoptosis in CML CD34+ cells, including the more primitive quiescent population, while also causing increased apoptosis in a population enriched for CML LSCs based on its surface marker expression (CD34+ CD38-). Finally given the known importance of quiescence and self-renewal pathways in CML LSC persistence following TKI treatment, the role of transforming growth factor (TGF)-β1 and novel neurotransmitter mediated pathways in CML LSC quiescence and self-renewal was investigated based on the findings of a genome and epigenome-wide screen of primary CML LSCs and normal HSCs carried out in our laboratory. Using in vitro assays the putative role of the neuromediators norepinephrine and acethylcoline in CML LSC self-renewal was demonstrated. Moreover the role of TGF-β1 in inducing primary CML LSC quiescence mainly by modulating the AKT pathway was also demonstrated. Overall the work presented in this thesis has furthered our understanding of the role of both autocrine and paracrine known and novel regulators of haemopoiesis in several aspects of CML SPC biology such as their survival, proliferation and self-renewal. Furthermore the efficacy in eradicating CML SPC of therapeutic strategies targeting some of these GF signals has been explored in vitro, thus providing evidence supporting their subsequent testing in in vivo assays and in due course in clinical studies. It is hoped therefore that the work presented will contribute to devise novel therapeutic strategies to eradicate CML LSC and in turn lead to a cure for CML patients

Extractive Conversation Summarization Driven by Textual Entailment Prediction

Summarizing conversations like meetings, email threads or discussion forums poses relevant challenges on how to model the dialogue structure. Existing approaches mainly focus on premise-claim entailment relationships while neglecting contrasting or uncertain assertions. Furthermore, existing techniques are abstractive, thus requiring a training set consisting of humanly generated summaries. With the twofold aim of enriching the dialogue representation and addressing conversation summarization in the absence of training data, we present an extractive conversation summarization pipeline. We explore the use of contradictions and neutral premise-claim relations, both in the same document or in different documents. The results achieved on four datasets covering different domains show that applying unsupervised methods on top of a refined premise-claim selection achieves competitive performance in most domains

Epigenetic regulators as promising therapeutic targets in acute myeloid leukemia.

Acute myeloid leukemia (AML), the most prevalent acute leukemia in adults, is an aggressive hematological malignancy arising in hematopoietic stem and progenitor cells. With the exception of a few specific AML subtypes, the mainstays of treatment have not significantly changed over the last 20 years, and are still based on standard cytotoxic chemotherapy. As a result, clinical outcome remains poor for the majority of patients, with overall long-term survival in the region of 20-30%. Recent successes in characterizing the genetic landscape of AML have highlighted that, despite its heterogeneity, many cases of AML carry recurrent mutations in genes encoding epigenetic regulators. Transcriptional dysregulation and altered epigenetic function have therefore emerged as exciting areas in AML research and it is becoming increasingly clear that epigenetic dysfunction is central to leukemogenesis in AML. This has subsequently paved the way for the development of epigenetically targeted therapies. In this review, we will discuss the most recent advances in our understanding of the role of epigenetic dysregulation in AML pathobiology. We will particularly focus on those altered epigenetic programs that have been shown to be central to the development and maintenance of AML in preclinical models. We will discuss the recent development of therapeutics specifically targeting these key epigenetic programs in AML, describe their mechanism of action and present their current clinical development. Finally, we will discuss the opportunities presented by epigenetically targeted therapy in AML and will highlight future challenges ahead for the AML community, to ensure that these novel therapeutics are optimally translated into clinical practice and result in clinical improvement for AML patients.We would like to thank all the members of the Huntly laboratory and our funders Leukaemia Lymphoma Research, Kay Kendall Leukaemia fund, the Medical Research Council UK, the Wellcome Trust, the Cambridge NIHR Biomedical Research Centre, Leukemia & Lymphoma Society US, the Academy of Medical Sciences UK and Lady Tata Memorial Trust. We apologise to writers whose work we have failed to cite due to space constraints.This is the author accepted manuscript. The final version is available via SAGE at http://dx.doi.org/10.1177/204062071557761

High prevalence of heparin induced thrombocytopenia with thrombosis among patients with essential thrombocytemia carrying V617F mutation.

Arterial and venous complications are major causes of morbidity and mortality in myeloproliferative neoplasms (MPNs). MPNs patients, frequently receive heparin. Heparin-induced thrombocytopenia (HIT) is a rare but potentially life-threatening complication resulting in a severe acquired thrombophilic condition. We carried out a retrospective analysis to evaluate occurrence of new thrombotic events during heparin therapy in essential thrombocythemia (ET) patients. We studied 108 ET patients on heparin for treatment of previous thrombotic events or in thromboprophilaxis. Fifty-eight of them carried JAK 2 V617F mutation while 50 patients were without V617F mutation. Ten patients, among those with JAK 2 V617F mutation after a median of 10 days from heparin treatment presented a platelet drop, new thrombotic events and in 10/10 cases heparin-related antibodies were found. In the other group, two patients (4%) presented a platelet drop, thrombotic manifestations and heparin related antibodies. Our data show that HIT is more frequent, during heparin treatment, in patients with ET carrying V617F mutation, as compared with patients without mutations (P = 0.029). ET with V617F mutation seems to be associated with higher risk of thrombotic complications during heparin treatment. Monitoring platelet counts very closely during the course of heparin is essential especially in ET patients in which platelet drop may be hidden by constitutional thrombocytosis

Contrasting requirements during disease evolution identify EZH2 as a therapeutic target in AML

This study demonstrates that EZH2 has stage-specific and diametrically opposite roles during the induction and maintenance stages of AML. However, different transcriptional programs are affected at each stage, identifying mutant EZH2 as a prognostic marker and paradoxically wild-type EZH2 as a potential therapeutic targetThe Huntly laboratory is funded by CRUK (Programme C18680/A25508), ERC (Grant 647685 COMAL), KKLF, MRC, Bloodwise, the Wellcome Trust (WT) and the Cambridge NIHR BRC. F.B. is a recipient of a Wellcome Trust PhD for Clinicians award. P.G. is funded by the Wellcome Trust (109967/Z/15/Z). We acknowledge the WT/MRC centre grant (097922/Z/11/Z) and support from WT strategic award 100140. Research in the laboratory is also supported by core funding from Wellcome and MRC to the Wellcome-MRC Cambridge Stem Cell Institute. We are grateful to Chiara Cossetti, Gabriela Grondys-Kotarba and Reiner Schulte at the CIMR Flow Cytometry Core for their invaluable help and advice with cell sorting. This research was supported by the Cambridge NIHR BRC Cell Phenotyping Hub. Patient samples were received from the UK NCRI AML trials. The authors declare no competing financial interests

Cohesin-dependent regulation of gene expression during differentiation is lost in cohesin-mutated myeloid malignancies.

Cohesin complex disruption alters gene expression, and cohesin mutations are common in myeloid neoplasia, suggesting a critical role in hematopoiesis. Here, we explore cohesin dynamics and regulation of hematopoietic stem cell homeostasis and differentiation. Cohesin binding increases at active regulatory elements only during erythroid differentiation. Prior binding of the repressive Ets transcription factor Etv6 predicts cohesin binding at these elements and Etv6 interacts with cohesin at chromatin. Depletion of cohesin severely impairs erythroid differentiation, particularly at Etv6-prebound loci, but augments self-renewal programs. Together with corroborative findings in acute myeloid leukemia and myelodysplastic syndrome patient samples, these data suggest cohesin-mediated alleviation of Etv6 repression is required for dynamic expression at critical erythroid genes during differentiation and how this may be perturbed in myeloid malignancies