Areas of Research
Epigenetic regulation of myeloma
Multiple myeloma is in many ways a disease driven by inappropriate gene expression. It is characterised by the aberrant activation of gene regulatory elements known as enhancers, stimulating the upregulation of key oncogenes. Blocking this behaviour is therefore a promising strategy for myeloma treatment, and many therapeutic strategies directly or indirectly target gene regulatory pathways.
The lab studies the epigenetic regulation of gene expression, focused on the way these processes are dysregulated in multiple myeloma. We have a particular interest in understanding the role of oncogenic enhancer activity in driving myeloma-specific transcriptional profiles, and identifying the factors responsible for this behaviour. A major goal of the lab is to identify potential therapeutic targets that could be developed as novel therapies for multiple myeloma.
We use a variety of high-throughput genomics techniques to study the chromatin landscape, including ChIP-seq, ATAC-seq and RNA-seq. We have optimised TOPmentation, a small cell-number technique that allows us to characterise the chromatin profile of myeloma patient samples. In addition, we use the 3C technology Micro-Capture-C to map the physical association of enhancers and promoters. By combining these techniques with genetic and pharmacological manipulation of myeloma cell lines, we are able to explore mechanistically enhancer function and regulation.
Mechanisms of myeloma drug resistance
Relapse is very common in myeloma after initial treatment. Patients typically enter remission following treatment, but invariably relapse, often with resistance to one or more of these drugs. There is therefore a pressing need to understand the mechanisms that drive this resistance to find ways to counteract it. We are working to identify and understand epigenetic mechanisms that drive drug resistance via changes in gene expression, which therefore may be reversed to resensitise cells to therapy.
Our team
Nick Crump (he/him)
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Nick Crump (he/him)
Kay Kendall Leukaemia Fund Intermediate Fellow
Jinglin Zhou (he/him)
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Jinglin Zhou (he/him)
PhD student
Jason Taslim (he/him)
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Jason Taslim (he/him)
Research assistant
Sophie Ball (she/her)
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Sophie Ball (she/her)
PhD student
Funders
Research Publications
Results
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Journal articleHarman JR, Thorne R, Jamilly M, et al., 2021,
A KMT2A-AFFI gene regulatory network highlights the role of core transcription factors and reveals the regulatory logic of key downstream target genes
, Genome Research, Vol: 31, Pages: 1159-1173, ISSN: 1054-9803Regulatory interactions mediated by transcription factors (TFs) make up complex networks that control cellular behavior. Fully understanding these gene regulatory networks (GRNs) offers greater insight into the consequences of disease-causing perturbations than can be achieved by studying single TF binding events in isolation. Chromosomal translocations of the lysine methyltransferase 2A (KMT2A) gene produce KMT2A fusion proteins such as KMT2A-AFF1 (previously MLL-AF4), causing poor prognosis acute lymphoblastic leukemias (ALLs) that sometimes relapse as acute myeloid leukemias (AMLs). KMT2A-AFF1 drives leukemogenesis through direct binding and inducing the aberrant overexpression of key genes, such as the anti-apoptotic factor BCL2 and the proto-oncogene MYC. However, studying direct binding alone does not incorporate possible network-generated regulatory outputs, including the indirect induction of gene repression. To better understand the KMT2A-AFF1-driven regulatory landscape, we integrated ChIP-seq, patient RNA-seq, and CRISPR essentiality screens to generate a model GRN. This GRN identified several key transcription factors such as RUNX1 that regulate target genes downstream of KMT2A-AFF1 using feed-forward loop (FFL) and cascade motifs. A core set of nodes are present in both ALL and AML, and CRISPR screening revealed several factors that help mediate response to the drug venetoclax. Using our GRN, we then identified a KMT2A-AFF1:RUNX1 cascade that represses CASP9, as well as KMT2A-AFF1-driven FFLs that regulate BCL2 and MYC through combinatorial TF activity. This illustrates how our GRN can be used to better connect KMT2A-AFF1 behavior to downstream pathways that contribute to leukemogenesis, and potentially predict shifts in gene expression that mediate drug response.
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Journal articleCrump NT, Hadjinicolaou A, Xia M, et al., 2021,
Chromatin accessibility governs the differential response of cancer and T cells to arginine starvation
, Cell Reports, Vol: 35, ISSN: 2211-1247Depleting the microenvironment of important nutrients such as arginine is a key strategy for immune evasion by cancer cells. Many tumors overexpress arginase, but it is unclear how these cancers, but not T cells, tolerate arginine depletion. In this study, we show that tumor cells synthesize arginine from citrulline by upregulating argininosuccinate synthetase 1 (ASS1). Under arginine starvation, ASS1 transcription is induced by ATF4 and CEBPβ binding to an enhancer within ASS1. T cells cannot induce ASS1, despite the presence of active ATF4 and CEBPβ, as the gene is repressed. Arginine starvation drives global chromatin compaction and repressive histone methylation, which disrupts ATF4/CEBPβ binding and target gene transcription. We find that T cell activation is impaired in arginine-depleted conditions, with significant metabolic perturbation linked to incomplete chromatin remodeling and misregulation of key genes. Our results highlight a T cell behavior mediated by nutritional stress, exploited by cancer cells to enable pathological immune evasion.
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Journal articleCrump NT, Ballabio E, Godfrey L, et al., 2021,
BET inhibition disrupts transcription but retains enhancer-promoter contact
, Nature Communications, Vol: 12, ISSN: 2041-1723Enhancers are DNA sequences that enable complex temporal and tissue-specific regulation of genes in higher eukaryotes. Although it is not entirely clear how enhancer-promoter interactions can increase gene expression, this proximity has been observed in multiple systems at multiple loci and is thought to be essential for the maintenance of gene expression. Bromodomain and Extra-Terminal domain (BET) and Mediator proteins have been shown capable of forming phase condensates and are thought to be essential for super-enhancer function. Here, we show that targeting of cells with inhibitors of BET proteins or pharmacological degradation of BET protein Bromodomain-containing protein 4 (BRD4) has a strong impact on transcription but very little impact on enhancer-promoter interactions. Dissolving phase condensates reduces BRD4 and Mediator binding at enhancers and can also strongly affect gene transcription, without disrupting enhancer-promoter interactions. These results suggest that activation of transcription and maintenance of enhancer-promoter interactions are separable events. Our findings further indicate that enhancer-promoter interactions are not dependent on high levels of BRD4 and Mediator, and are likely maintained by a complex set of factors including additional activator complexes and, at some sites, CTCF and cohesin.
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Journal articleGodfrey L, Crump NT, O'Byrne S, et al., 2021,
H3K79me2/3 controls enhancer–promoter interactions and activation of the pan-cancer stem cell marker PROM1/CD133 in MLL-AF4 leukemia cells
, Leukemia, Vol: 35, Pages: 90-106, ISSN: 0887-6924MLL gene rearrangements (MLLr) are a common cause of aggressive, incurable acute lymphoblastic leukemias (ALL) in infants and children, most of which originate in utero. The most common MLLr produces an MLL-AF4 fusion protein. MLL-AF4 promotes leukemogenesis by activating key target genes, mainly through recruitment of DOT1L and increased histone H3 lysine-79 methylation (H3K79me2/3). One key MLL-AF4 target gene is PROM1, which encodes CD133 (Prominin-1). CD133 is a pentaspan transmembrane glycoprotein that represents a potential pan-cancer target as it is found on multiple cancer stem cells. Here we demonstrate that aberrant PROM1/CD133 expression is essential for leukemic cell growth, mediated by direct binding of MLL-AF4. Activation is controlled by an intragenic H3K79me2/3 enhancer element (KEE) leading to increased enhancer–promoter interactions between PROM1 and the nearby gene TAPT1. This dual locus regulation is reflected in a strong correlation of expression in leukemia. We find that in PROM1/CD133 non-expressing cells, the PROM1 locus is repressed by polycomb repressive complex 2 (PRC2) binding, associated with reduced expression of TAPT1, partially due to loss of interactions with the PROM1 locus. Together, these results provide the first detailed analysis of PROM1/CD133 regulation that explains CD133 expression in MLLr ALL.
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Conference paperFidyt K, Cyran J, Pastorczak A, et al., 2020,
Pharmacological Induction of NOXA Sensitizes High-Risk B Cell Acute Lymphoblastic Leukemia Cells to Venetoclax
, 62nd Annual Meeting of the American-Society-of-Hematology (ASH), Publisher: ELSEVIER, ISSN: 0006-4971
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