Guy Pratt - Academia.edu (original) (raw)

Papers by Guy Pratt

Research paper thumbnail of T-cell number and subtype influence the disease course of primary chronic lymphocytic leukaemia xenografts in alymphoid mice

Disease models & mechanisms, Jan 20, 2015

Chronic lymphocytic leukaemia (CLL) cells require micorenvironmental support for their proliferat... more Chronic lymphocytic leukaemia (CLL) cells require micorenvironmental support for their proliferation. This can be recapitulated in highly immunocompromised hosts in the presence of T-cells and other supporting cells. Current primary CLL xenograft models suffer from limited duration of tumour cell engraftment coupled with gradual T-cell outgrowth. Thus, a greater understanding of the interaction between CLL and T-cells could improve their utility. In this study, using two distinct xenograft models, we investigated whether xenografts recapitulate CLL biology including natural environmental interactions with B-cell receptors and T-cells and whether manipulation of autologous T-cells can expand the duration of CLL engraftment. We observed that primary CLL xenografts recapitulated both the tumour phenotype and T-cell repertoire observed in patients and that engraftment was significantly shorter for progressive tumours. Reduction of patients' T-cells to 2-5% of the initial T-cell numb...

Research paper thumbnail of Time to redefine Myeloma

British journal of haematology, Jan 27, 2015

In November 2014 the International Myeloma Working Group (IMWG) revised the definition of multipl... more In November 2014 the International Myeloma Working Group (IMWG) revised the definition of multiple myeloma, such that asymptomatic patients with newly diagnosed multiple myeloma without any of the traditional 'CRAB' (hypercalcaemia, renal impairment, anaemia, bone disease) end organ damage criteria but with one of three new criteria would be recommended to start treatment. Previously, the standard of care for such patients was expectant management. These three new criteria are: greater than 60% clonal plasma cells on bone marrow biopsy, a serum free light chain (sFLC) ratio of >100 (the involved sFLC must be >100 mg/l) and greater than one unequivocal focal lesion on advanced imaging (low dose whole body computerized tomography, magnetic resonance imaging, (18) F fluorodeoxyglucose positron emission tomography). Although this would appear to affect a small number of patients, the impact of these changes are broad, leading to an increased use of advanced imaging, a deba...

Research paper thumbnail of Optimizing the management of patients with spinal myeloma disease

British Journal of Haematology, 2015

Myeloma is one of the most common malignancies that results in osteolytic lesions of the spine. C... more Myeloma is one of the most common malignancies that results in osteolytic lesions of the spine. Complications, including pathological fractures of the vertebrae and spinal cord compression, may cause severe pain, deformity and neurological sequelae. They may also have significant consequences for quality of life and prognosis for patients. For patients with known or newly diagnosed myeloma presenting with persistent back or radicular pain/weakness, early diagnosis of spinal myeloma disease is therefore essential to treat and prevent further deterioration. Magnetic resonance imaging is the initial imaging modality of choice for the evaluation of spinal disease. Treatment of the underlying malignancy with systemic chemotherapy together with supportive bisphosphonate treatment reduces further vertebral damage. Additional interventions such as cement augmentation, radiotherapy, or surgery are often necessary to prevent, treat and control spinal complications. However, optimal management is dependent on the individual nature of the spinal involvement and requires careful assessment and appropriate intervention throughout. This article reviews the treatment and management options for spinal myeloma disease and highlights the value of defined pathways to enable the proper management of patients affected by it.

Research paper thumbnail of Poor functional antibody responses are present in nearly all patients with chronic lymphocytic leukaemia, irrespective of total IgG concentration, and are associated with increased risk of infection

British Journal of Haematology, 2015

Research paper thumbnail of Targeting the Ataxia Telangiectasia Mutated-null phenotype in chronic lymphocytic leukemia with pro-oxidants

Haematologica, Jan 3, 2015

Inactivation of the Ataxia Telangiectasia Mutated gene in chronic lymphocytic leukemia results in... more Inactivation of the Ataxia Telangiectasia Mutated gene in chronic lymphocytic leukemia results in resistance to p53-dependent apoptosis and inferior responses to treatment with DNA damaging agents. Hence, p53-independent strategies are required to target Ataxia Telangiectasia Mutated-deficient chronic lymphocytic leukemia. As Ataxia Telangiectasia Mutated has been implicated in redox homeostasis, we investigated the effect of the Ataxia Telangiectasia Mutated-null chronic lymphocytic leukemia genotype on cellular responses to oxidative stress with a view to therapeutic targeting. We found that in comparison to Ataxia Telangiectasia Mutated-wild type chronic lymphocytic leukemia, pro-oxidant treatment of Ataxia Telangiectasia Mutated-null cells led to reduced binding of NF-E2 p45-related factor-2 to antioxidant response elements and thus decreased expression of target genes. Furthermore, Ataxia Telangiectasia Mutated-null chronic lymphocytic leukemia cells contained lower levels of a...

Research paper thumbnail of The interleukin-6 receptor alpha-chain (CD126) is expressed by neoplastic but not normal plasma cells

Blood, 2000

Interleukin-6 (IL-6) is reported to be central to the pathogenesis of myeloma, inducing prolifera... more Interleukin-6 (IL-6) is reported to be central to the pathogenesis of myeloma, inducing proliferation and inhibiting apoptosis in neoplastic plasma cells. Therefore, abrogating IL-6 signaling is of therapeutic interest, particularly with the development of humanized anti-IL-6 receptor (IL-6R) antibodies. The use of such antibodies clinically requires an understanding of IL-6R expression on neoplastic cells, particularly in the cycling fraction. IL-6R expression levels were determined on plasma cells from patients with myeloma (n = 93) and with monoclonal gammopathy of undetermined significance (MGUS) or plasmacytoma (n = 66) and compared with the levels found on normal plasma cells (n = 11). In addition, 4-color flow cytometry was used to assess the differential expression by stage of differentiation and cell cycle status of the neoplastic plasma cells. IL-6R alpha chain (CD126) was not detectable in normal plasma cells, but was expressed in approximately 90% of patients with myelom...

Research paper thumbnail of Arginine dependence of Acute Myeloid Leukaemia blast proliferation: a novel therapeutic target

Blood, Jan 20, 2015

Acute Myeloid Leukaemia (AML) is one of the most common acute leukaemias in adults and children, ... more Acute Myeloid Leukaemia (AML) is one of the most common acute leukaemias in adults and children, yet significant numbers of patients relapse and die of disease. In this study we identify the dependence of AML blasts on arginine for proliferation. We show AML blasts constitutively express the arginine transporters CAT-1 and CAT-2B, and that the majority of newly diagnosed patients' blasts have deficiencies in the arginine recycling pathway enzymes arginosuccinate synthase (ASS) and ornithine transcarbamylase (OTC), making them arginine auxotrophic. BCT-100, a pegylated human recombinant arginase, leads to a rapid depletion in extracellular and intracellular arginine concentrations, resulting in arrest of AML blast proliferation and a reduction in AML engraftment in vivo. BCT-100 as a single agent causes significant death of AML blasts from adults and children, and acts synergistically in combination with cytarabine. Using RNA-sequencing 20 further candidate genes which correlated...

Research paper thumbnail of Running Title: Anti-viral responses in human bone marrow

Research paper thumbnail of A genome-wide association study identifies multiple susceptibility loci for chronic lymphocytic leukemia

Research paper thumbnail of Genomic characterization of the chromosomal breakpoints of t(4;14) of multiple myeloma suggests more than one possible aetiological mechanism

Research paper thumbnail of Common variants at 2q37.3, 8q24.21, 15q21.3 and 16q24.1 influence chronic lymphocytic leukemia risk

Nature Genetics, 2010

To identify new risk variants for chronic lymphocytic leukemia (CLL), we conducted a genome-wide ... more To identify new risk variants for chronic lymphocytic leukemia (CLL), we conducted a genome-wide association study of 299,983 tagging SNPs, with validation in four additional series totaling 2,503 cases and 5,789 controls. We identified four new risk loci for CLL at 2q37.3 (rs757978, FARP2; odds ratio (OR) = 1.39; P = 2.11 x 10(-9)), 8q24.21 (rs2456449; OR = 1.26; P = 7.84 x 10(-10)), 15q21.3 (rs7169431; OR = 1.36; P = 4.74 x 10(-7)) and 16q24.1 (rs305061; OR = 1.22; P = 3.60 x 10(-7)). We also found evidence for risk loci at 15q25.2 (rs783540, CPEB1; OR = 1.18; P = 3.67 x 10(-6)) and 18q21.1 (rs1036935; OR = 1.22; P = 2.28 x 10(-6)). These data provide further evidence for genetic susceptibility to this B-cell hematological malignancy.

Research paper thumbnail of Common variation at 3q26.2, 6p21.33, 17p11.2 and 22q13.1 influences multiple myeloma risk

Nature Genetics, 2013

To identify variants for multiple myeloma risk, we conducted a genome-wide association study with... more To identify variants for multiple myeloma risk, we conducted a genome-wide association study with validation in additional series totaling 4,692 individuals with multiple myeloma (cases) and 10,990 controls. We identified four risk loci at 3q26.2 (rs10936599, P = 8.70 × 10(-14)), 6p21.33 (rs2285803, PSORS1C2, P = 9.67 × 10(-11)), 17p11.2 (rs4273077, TNFRSF13B, P = 7.67 × 10(-9)) and 22q13.1 (rs877529, CBX7, P = 7.63 × 10(-16)). These data provide further evidence for genetic susceptibility to this B-cell hematological malignancy, as well as insight into the biological basis of predisposition.

Research paper thumbnail of A genome-wide association study identifies six susceptibility loci for chronic lymphocytic leukemia

Nature Genetics, 2008

We conducted a genome-wide association study of 299,983 tagging SNPs for chronic lymphocytic leuk... more We conducted a genome-wide association study of 299,983 tagging SNPs for chronic lymphocytic leukemia (CLL) and performed validation in two additional series totaling 1,529 cases and 3,115 controls. We identified six previously unreported CLL risk loci at 2q13 (rs17483466; P ¼ 2.36 Â 10 À10 ), 2q37.1 (rs13397985, SP140; P ¼ 5.40 Â 10 À10 ), 6p25.3 (rs872071, IRF4; P ¼ 1.91 Â 10 À20 ), 11q24.1 (rs735665; P ¼ 3.78 Â 10 À12 ), 15q23 (rs7176508; P ¼ 4.54 Â 10 À12 )a n d 19q13.32 (rs11083846, PRKD2; P ¼ 3.96 Â 10 À9 ). These data provide the first evidence for the existence of common, lowpenetrance susceptibility to a hematological malignancy and new insights into disease causation in CLL.

Research paper thumbnail of The NF- B Inhibitor LC-1 Has Single Agent Activity in Multiple Myeloma Cells and Synergizes with Bortezomib

Molecular Cancer Therapeutics, 2010

Multiple myeloma remains incurable with conventional therapeutics. Thus, new treatments for this ... more Multiple myeloma remains incurable with conventional therapeutics. Thus, new treatments for this condition are clearly required. In this study we evaluated the novel NF-kappaB inhibitor LC-1 in multiple myeloma cell lines and plasma cells derived from multiple myeloma patients. LC-1 was cytotoxic to multiple myeloma cell lines H929, U266, and JJN3, and induced apoptosis in a dose-dependent manner with an overall LD(50) of 3.6 micromol/L (+/-1.8) after 48 hours in culture. Primary multiple myeloma cells, identified by CD38 and CD138 positivity, had a mean LD(50) for LC-1 of 4.9 micromol/L (+/-1.6); normal bone marrow cells were significantly less sensitive to the cytotoxic effects of LC-1 (P = 0.0002). Treatment of multiple myeloma cell lines with LC-1 resulted in decreased nuclear localization of the NF-kappaB subunit Rel A and the inhibition of NF-kappaB target genes. In addition, LC-1 showed synergy with melphalan, bortezomib, and doxorubicin (combination indices of 0.72, 0.61, and 0.78, respectively), and was more effective when cells were cultured on fibronectin. These data show that LC-1 has activity in multiple myeloma cell lines and primary multiple myeloma cells, and its ability to inhibit NF-kappaB seems important for its cytotoxic effects. Furthermore, LC-1-induced transcriptional suppression of survivin and MCL1 provides a potential explanation for its synergy with conventional agents.

Research paper thumbnail of Two germ line polymorphisms of the tumour suppressor gene p53 may influence the biology of chronic lymphocytic leukaemia

Leukemia Research, 2006

Chronic lymphocytic leukaemia (CLL) is characterised by the accumulation of mature B lymphocytes.... more Chronic lymphocytic leukaemia (CLL) is characterised by the accumulation of mature B lymphocytes. Defects in the tumour suppressor gene p53 pathway are known to be important in CLL and p53 inactivation is associated with a particularly aggressive form of CLL. A single nucleotide polymorphism (SNP) in codon 72 of TP53 leads to a single amino acid change leading to a change in apoptotic potential and alters prognosis in squamous carcinomas. A polymorphism within intron 6 of TP53 has been postulated to alter the susceptibility to lung cancer. Our study looked at the influence of these two polymorphisms in a cohort of approximately 200 CLL patients. The codon 72 polymorphism A2/A2 genotype (homozygous arginine) was associated with an increased susceptibility to CLL and CD38 negativity but did not appear to influence other biological behaviour or clinical response. The intron 6 polymorphism A2/A2 genotype was strongly associated with early stage disease, CD38 negativity and a longer time to first treatment. The effect on time to treatment did not retain significance in multivariate analysis and the polymorphism did not predict for overall survival (OS). Detailed investigation of the complete TP53 genotype is warranted to further characterise the role of SNPs in p53 and their influence on CLL.

Research paper thumbnail of Treatment of primary CLL cells with bezafibrate and medroxyprogesterone acetate induces apoptosis and represses the pro-proliferative signal of CD40-ligand, in part through increased 15dΔ12,14,PGJ2

Research paper thumbnail of Isolation and characterisation of recombination events involving immunoglobulin heavy chain switch regions in multiple myeloma using long distance vectorette PCR (LDV-PCR)

Leukemia, 1999

Immunoglobulin class switching occurs as a result of recombination between pairs of switch region... more Immunoglobulin class switching occurs as a result of recombination between pairs of switch region sequences located 5' to each constant heavy chain gene except Cdelta. In the B cell neoplasm multiple myeloma, tumour cells have generally undergone class switching and often contain oncogenic sequences translocated into switch regions, presumably as a result of aberrant switch recombination. We have developed a method (LDV-PCR) which combines long distance PCR with one-sided vectorette PCR that is capable of detecting and isolating both normal and aberrant switch recombination breakpoints from multiple myeloma cell lines and primary multiple myeloma tumour material. Using LDV-PCR we have directly cloned the translocation breakpoints present in two multiple myeloma cell lines and isolated a normal productive switch recombination event from a primary tumour. Furthermore, we have isolated a novel translocation t(14;22)(q32;q12) from a primary tumour sample and have demonstrated that internal deletions within switch regions can occur in multiple myeloma cells. Compared to a Southern blotting approach, LDV-PCR is simpler and more rapid to perform, allows the simultaneous detection and isolation of recombination events, and can also be applied to amounts of DNA which are too low to permit the conventional cloning of recombination breakpoints.

Research paper thumbnail of Highly purified CD38+ and CD38− sub-clones derived from the same chronic lymphocytic leukemia patient have distinct gene expression signatures despite their monoclonal origin

Leukemia, 2007

CD38 expression is an important prognostic marker in chronic lymphocytic leukemia (CLL) with high... more CD38 expression is an important prognostic marker in chronic lymphocytic leukemia (CLL) with high levels of CD38 associated with shorter overall survival. In this study, we used gene expression profiling and protein analysis of highly purified cell-sorted CD38(+) and CD38(-) chronic lymphocytic leukemia cells to elucidate a molecular basis for the association between CD38 expression and inferior clinical outcome. Paired CD38(+) and CD38(-) CLL cells derived from the same patient were shown to be monoclonal by V(H) gene sequencing but despite this, CD38(+) CLL cells possessed a distinct gene expression profile when compared with their CD38(-) sub-clones. Importantly, CD38(+) CLL cells relatively over expressed vascular endothelial growth factor (VEGF) and appeared to preferentially utilize an internal autocrine VEGF survival loop. Elevated VEGF expression was associated with increased expression of the anti-apoptotic protein Mcl-1. Inhibition of VEGF receptor signaling also resulted in a reduction in cell viability. In contrast, exogenous VEGF caused a significant increase in CD38(-) CLL cell viability and a marked induction of Mcl-1; both effects were less obvious in CD38(+) CLL cells. Taken together, our data provide a biological rationale for the poor prognosis of CD38(+) CLL and indicate that both VEGF and Mcl-1 may prove to be useful therapeutic targets.

Research paper thumbnail of Variant IRF4/MUM1 associates with CD38 status and treatment-free survival in chronic lymphocytic leukaemia

Research paper thumbnail of Lycorine sensitizes CD40 ligand-protected chronic lymphocytic leukemia cells to bezafibrate- and medroxyprogesterone acetate-induced apoptosis but dasatanib does not overcome reported CD40-mediated drug resistance

Haematologica, 2010

Tumor cells in chronic lymphocytic leukemia accumulate in the periphery through the proliferation... more Tumor cells in chronic lymphocytic leukemia accumulate in the periphery through the proliferation of a minority of cells in lymph nodes. The proliferative and survival signals in these proliferation centers include interactions with T lymphocytes expressing CD40 ligand. We have demonstrated that the low toxicity combination of bezafibrate and medroxyprogesterone acetate induces mitochondrial superoxide-mediated apoptosis of non-CD40-liganded cells but not of cells exposed to CD40 ligand. Here, we assessed the ability of dasatinib and lycorine to restore bezafibrate-and medroxyprogesterone acetate-induced apoptosis in cells exposed to CD40 ligand. In parallel experiments we compared the ability of dasatinib to induce apoptosis of cells co-treated with fludarabine.

Research paper thumbnail of T-cell number and subtype influence the disease course of primary chronic lymphocytic leukaemia xenografts in alymphoid mice

Disease models & mechanisms, Jan 20, 2015

Chronic lymphocytic leukaemia (CLL) cells require micorenvironmental support for their proliferat... more Chronic lymphocytic leukaemia (CLL) cells require micorenvironmental support for their proliferation. This can be recapitulated in highly immunocompromised hosts in the presence of T-cells and other supporting cells. Current primary CLL xenograft models suffer from limited duration of tumour cell engraftment coupled with gradual T-cell outgrowth. Thus, a greater understanding of the interaction between CLL and T-cells could improve their utility. In this study, using two distinct xenograft models, we investigated whether xenografts recapitulate CLL biology including natural environmental interactions with B-cell receptors and T-cells and whether manipulation of autologous T-cells can expand the duration of CLL engraftment. We observed that primary CLL xenografts recapitulated both the tumour phenotype and T-cell repertoire observed in patients and that engraftment was significantly shorter for progressive tumours. Reduction of patients' T-cells to 2-5% of the initial T-cell numb...

Research paper thumbnail of Time to redefine Myeloma

British journal of haematology, Jan 27, 2015

In November 2014 the International Myeloma Working Group (IMWG) revised the definition of multipl... more In November 2014 the International Myeloma Working Group (IMWG) revised the definition of multiple myeloma, such that asymptomatic patients with newly diagnosed multiple myeloma without any of the traditional 'CRAB' (hypercalcaemia, renal impairment, anaemia, bone disease) end organ damage criteria but with one of three new criteria would be recommended to start treatment. Previously, the standard of care for such patients was expectant management. These three new criteria are: greater than 60% clonal plasma cells on bone marrow biopsy, a serum free light chain (sFLC) ratio of >100 (the involved sFLC must be >100 mg/l) and greater than one unequivocal focal lesion on advanced imaging (low dose whole body computerized tomography, magnetic resonance imaging, (18) F fluorodeoxyglucose positron emission tomography). Although this would appear to affect a small number of patients, the impact of these changes are broad, leading to an increased use of advanced imaging, a deba...

Research paper thumbnail of Optimizing the management of patients with spinal myeloma disease

British Journal of Haematology, 2015

Myeloma is one of the most common malignancies that results in osteolytic lesions of the spine. C... more Myeloma is one of the most common malignancies that results in osteolytic lesions of the spine. Complications, including pathological fractures of the vertebrae and spinal cord compression, may cause severe pain, deformity and neurological sequelae. They may also have significant consequences for quality of life and prognosis for patients. For patients with known or newly diagnosed myeloma presenting with persistent back or radicular pain/weakness, early diagnosis of spinal myeloma disease is therefore essential to treat and prevent further deterioration. Magnetic resonance imaging is the initial imaging modality of choice for the evaluation of spinal disease. Treatment of the underlying malignancy with systemic chemotherapy together with supportive bisphosphonate treatment reduces further vertebral damage. Additional interventions such as cement augmentation, radiotherapy, or surgery are often necessary to prevent, treat and control spinal complications. However, optimal management is dependent on the individual nature of the spinal involvement and requires careful assessment and appropriate intervention throughout. This article reviews the treatment and management options for spinal myeloma disease and highlights the value of defined pathways to enable the proper management of patients affected by it.

Research paper thumbnail of Poor functional antibody responses are present in nearly all patients with chronic lymphocytic leukaemia, irrespective of total IgG concentration, and are associated with increased risk of infection

British Journal of Haematology, 2015

Research paper thumbnail of Targeting the Ataxia Telangiectasia Mutated-null phenotype in chronic lymphocytic leukemia with pro-oxidants

Haematologica, Jan 3, 2015

Inactivation of the Ataxia Telangiectasia Mutated gene in chronic lymphocytic leukemia results in... more Inactivation of the Ataxia Telangiectasia Mutated gene in chronic lymphocytic leukemia results in resistance to p53-dependent apoptosis and inferior responses to treatment with DNA damaging agents. Hence, p53-independent strategies are required to target Ataxia Telangiectasia Mutated-deficient chronic lymphocytic leukemia. As Ataxia Telangiectasia Mutated has been implicated in redox homeostasis, we investigated the effect of the Ataxia Telangiectasia Mutated-null chronic lymphocytic leukemia genotype on cellular responses to oxidative stress with a view to therapeutic targeting. We found that in comparison to Ataxia Telangiectasia Mutated-wild type chronic lymphocytic leukemia, pro-oxidant treatment of Ataxia Telangiectasia Mutated-null cells led to reduced binding of NF-E2 p45-related factor-2 to antioxidant response elements and thus decreased expression of target genes. Furthermore, Ataxia Telangiectasia Mutated-null chronic lymphocytic leukemia cells contained lower levels of a...

Research paper thumbnail of The interleukin-6 receptor alpha-chain (CD126) is expressed by neoplastic but not normal plasma cells

Blood, 2000

Interleukin-6 (IL-6) is reported to be central to the pathogenesis of myeloma, inducing prolifera... more Interleukin-6 (IL-6) is reported to be central to the pathogenesis of myeloma, inducing proliferation and inhibiting apoptosis in neoplastic plasma cells. Therefore, abrogating IL-6 signaling is of therapeutic interest, particularly with the development of humanized anti-IL-6 receptor (IL-6R) antibodies. The use of such antibodies clinically requires an understanding of IL-6R expression on neoplastic cells, particularly in the cycling fraction. IL-6R expression levels were determined on plasma cells from patients with myeloma (n = 93) and with monoclonal gammopathy of undetermined significance (MGUS) or plasmacytoma (n = 66) and compared with the levels found on normal plasma cells (n = 11). In addition, 4-color flow cytometry was used to assess the differential expression by stage of differentiation and cell cycle status of the neoplastic plasma cells. IL-6R alpha chain (CD126) was not detectable in normal plasma cells, but was expressed in approximately 90% of patients with myelom...

Research paper thumbnail of Arginine dependence of Acute Myeloid Leukaemia blast proliferation: a novel therapeutic target

Blood, Jan 20, 2015

Acute Myeloid Leukaemia (AML) is one of the most common acute leukaemias in adults and children, ... more Acute Myeloid Leukaemia (AML) is one of the most common acute leukaemias in adults and children, yet significant numbers of patients relapse and die of disease. In this study we identify the dependence of AML blasts on arginine for proliferation. We show AML blasts constitutively express the arginine transporters CAT-1 and CAT-2B, and that the majority of newly diagnosed patients' blasts have deficiencies in the arginine recycling pathway enzymes arginosuccinate synthase (ASS) and ornithine transcarbamylase (OTC), making them arginine auxotrophic. BCT-100, a pegylated human recombinant arginase, leads to a rapid depletion in extracellular and intracellular arginine concentrations, resulting in arrest of AML blast proliferation and a reduction in AML engraftment in vivo. BCT-100 as a single agent causes significant death of AML blasts from adults and children, and acts synergistically in combination with cytarabine. Using RNA-sequencing 20 further candidate genes which correlated...

Research paper thumbnail of Running Title: Anti-viral responses in human bone marrow

Research paper thumbnail of A genome-wide association study identifies multiple susceptibility loci for chronic lymphocytic leukemia

Research paper thumbnail of Genomic characterization of the chromosomal breakpoints of t(4;14) of multiple myeloma suggests more than one possible aetiological mechanism

Research paper thumbnail of Common variants at 2q37.3, 8q24.21, 15q21.3 and 16q24.1 influence chronic lymphocytic leukemia risk

Nature Genetics, 2010

To identify new risk variants for chronic lymphocytic leukemia (CLL), we conducted a genome-wide ... more To identify new risk variants for chronic lymphocytic leukemia (CLL), we conducted a genome-wide association study of 299,983 tagging SNPs, with validation in four additional series totaling 2,503 cases and 5,789 controls. We identified four new risk loci for CLL at 2q37.3 (rs757978, FARP2; odds ratio (OR) = 1.39; P = 2.11 x 10(-9)), 8q24.21 (rs2456449; OR = 1.26; P = 7.84 x 10(-10)), 15q21.3 (rs7169431; OR = 1.36; P = 4.74 x 10(-7)) and 16q24.1 (rs305061; OR = 1.22; P = 3.60 x 10(-7)). We also found evidence for risk loci at 15q25.2 (rs783540, CPEB1; OR = 1.18; P = 3.67 x 10(-6)) and 18q21.1 (rs1036935; OR = 1.22; P = 2.28 x 10(-6)). These data provide further evidence for genetic susceptibility to this B-cell hematological malignancy.

Research paper thumbnail of Common variation at 3q26.2, 6p21.33, 17p11.2 and 22q13.1 influences multiple myeloma risk

Nature Genetics, 2013

To identify variants for multiple myeloma risk, we conducted a genome-wide association study with... more To identify variants for multiple myeloma risk, we conducted a genome-wide association study with validation in additional series totaling 4,692 individuals with multiple myeloma (cases) and 10,990 controls. We identified four risk loci at 3q26.2 (rs10936599, P = 8.70 × 10(-14)), 6p21.33 (rs2285803, PSORS1C2, P = 9.67 × 10(-11)), 17p11.2 (rs4273077, TNFRSF13B, P = 7.67 × 10(-9)) and 22q13.1 (rs877529, CBX7, P = 7.63 × 10(-16)). These data provide further evidence for genetic susceptibility to this B-cell hematological malignancy, as well as insight into the biological basis of predisposition.

Research paper thumbnail of A genome-wide association study identifies six susceptibility loci for chronic lymphocytic leukemia

Nature Genetics, 2008

We conducted a genome-wide association study of 299,983 tagging SNPs for chronic lymphocytic leuk... more We conducted a genome-wide association study of 299,983 tagging SNPs for chronic lymphocytic leukemia (CLL) and performed validation in two additional series totaling 1,529 cases and 3,115 controls. We identified six previously unreported CLL risk loci at 2q13 (rs17483466; P ¼ 2.36 Â 10 À10 ), 2q37.1 (rs13397985, SP140; P ¼ 5.40 Â 10 À10 ), 6p25.3 (rs872071, IRF4; P ¼ 1.91 Â 10 À20 ), 11q24.1 (rs735665; P ¼ 3.78 Â 10 À12 ), 15q23 (rs7176508; P ¼ 4.54 Â 10 À12 )a n d 19q13.32 (rs11083846, PRKD2; P ¼ 3.96 Â 10 À9 ). These data provide the first evidence for the existence of common, lowpenetrance susceptibility to a hematological malignancy and new insights into disease causation in CLL.

Research paper thumbnail of The NF- B Inhibitor LC-1 Has Single Agent Activity in Multiple Myeloma Cells and Synergizes with Bortezomib

Molecular Cancer Therapeutics, 2010

Multiple myeloma remains incurable with conventional therapeutics. Thus, new treatments for this ... more Multiple myeloma remains incurable with conventional therapeutics. Thus, new treatments for this condition are clearly required. In this study we evaluated the novel NF-kappaB inhibitor LC-1 in multiple myeloma cell lines and plasma cells derived from multiple myeloma patients. LC-1 was cytotoxic to multiple myeloma cell lines H929, U266, and JJN3, and induced apoptosis in a dose-dependent manner with an overall LD(50) of 3.6 micromol/L (+/-1.8) after 48 hours in culture. Primary multiple myeloma cells, identified by CD38 and CD138 positivity, had a mean LD(50) for LC-1 of 4.9 micromol/L (+/-1.6); normal bone marrow cells were significantly less sensitive to the cytotoxic effects of LC-1 (P = 0.0002). Treatment of multiple myeloma cell lines with LC-1 resulted in decreased nuclear localization of the NF-kappaB subunit Rel A and the inhibition of NF-kappaB target genes. In addition, LC-1 showed synergy with melphalan, bortezomib, and doxorubicin (combination indices of 0.72, 0.61, and 0.78, respectively), and was more effective when cells were cultured on fibronectin. These data show that LC-1 has activity in multiple myeloma cell lines and primary multiple myeloma cells, and its ability to inhibit NF-kappaB seems important for its cytotoxic effects. Furthermore, LC-1-induced transcriptional suppression of survivin and MCL1 provides a potential explanation for its synergy with conventional agents.

Research paper thumbnail of Two germ line polymorphisms of the tumour suppressor gene p53 may influence the biology of chronic lymphocytic leukaemia

Leukemia Research, 2006

Chronic lymphocytic leukaemia (CLL) is characterised by the accumulation of mature B lymphocytes.... more Chronic lymphocytic leukaemia (CLL) is characterised by the accumulation of mature B lymphocytes. Defects in the tumour suppressor gene p53 pathway are known to be important in CLL and p53 inactivation is associated with a particularly aggressive form of CLL. A single nucleotide polymorphism (SNP) in codon 72 of TP53 leads to a single amino acid change leading to a change in apoptotic potential and alters prognosis in squamous carcinomas. A polymorphism within intron 6 of TP53 has been postulated to alter the susceptibility to lung cancer. Our study looked at the influence of these two polymorphisms in a cohort of approximately 200 CLL patients. The codon 72 polymorphism A2/A2 genotype (homozygous arginine) was associated with an increased susceptibility to CLL and CD38 negativity but did not appear to influence other biological behaviour or clinical response. The intron 6 polymorphism A2/A2 genotype was strongly associated with early stage disease, CD38 negativity and a longer time to first treatment. The effect on time to treatment did not retain significance in multivariate analysis and the polymorphism did not predict for overall survival (OS). Detailed investigation of the complete TP53 genotype is warranted to further characterise the role of SNPs in p53 and their influence on CLL.

Research paper thumbnail of Treatment of primary CLL cells with bezafibrate and medroxyprogesterone acetate induces apoptosis and represses the pro-proliferative signal of CD40-ligand, in part through increased 15dΔ12,14,PGJ2

Research paper thumbnail of Isolation and characterisation of recombination events involving immunoglobulin heavy chain switch regions in multiple myeloma using long distance vectorette PCR (LDV-PCR)

Leukemia, 1999

Immunoglobulin class switching occurs as a result of recombination between pairs of switch region... more Immunoglobulin class switching occurs as a result of recombination between pairs of switch region sequences located 5' to each constant heavy chain gene except Cdelta. In the B cell neoplasm multiple myeloma, tumour cells have generally undergone class switching and often contain oncogenic sequences translocated into switch regions, presumably as a result of aberrant switch recombination. We have developed a method (LDV-PCR) which combines long distance PCR with one-sided vectorette PCR that is capable of detecting and isolating both normal and aberrant switch recombination breakpoints from multiple myeloma cell lines and primary multiple myeloma tumour material. Using LDV-PCR we have directly cloned the translocation breakpoints present in two multiple myeloma cell lines and isolated a normal productive switch recombination event from a primary tumour. Furthermore, we have isolated a novel translocation t(14;22)(q32;q12) from a primary tumour sample and have demonstrated that internal deletions within switch regions can occur in multiple myeloma cells. Compared to a Southern blotting approach, LDV-PCR is simpler and more rapid to perform, allows the simultaneous detection and isolation of recombination events, and can also be applied to amounts of DNA which are too low to permit the conventional cloning of recombination breakpoints.

Research paper thumbnail of Highly purified CD38+ and CD38− sub-clones derived from the same chronic lymphocytic leukemia patient have distinct gene expression signatures despite their monoclonal origin

Leukemia, 2007

CD38 expression is an important prognostic marker in chronic lymphocytic leukemia (CLL) with high... more CD38 expression is an important prognostic marker in chronic lymphocytic leukemia (CLL) with high levels of CD38 associated with shorter overall survival. In this study, we used gene expression profiling and protein analysis of highly purified cell-sorted CD38(+) and CD38(-) chronic lymphocytic leukemia cells to elucidate a molecular basis for the association between CD38 expression and inferior clinical outcome. Paired CD38(+) and CD38(-) CLL cells derived from the same patient were shown to be monoclonal by V(H) gene sequencing but despite this, CD38(+) CLL cells possessed a distinct gene expression profile when compared with their CD38(-) sub-clones. Importantly, CD38(+) CLL cells relatively over expressed vascular endothelial growth factor (VEGF) and appeared to preferentially utilize an internal autocrine VEGF survival loop. Elevated VEGF expression was associated with increased expression of the anti-apoptotic protein Mcl-1. Inhibition of VEGF receptor signaling also resulted in a reduction in cell viability. In contrast, exogenous VEGF caused a significant increase in CD38(-) CLL cell viability and a marked induction of Mcl-1; both effects were less obvious in CD38(+) CLL cells. Taken together, our data provide a biological rationale for the poor prognosis of CD38(+) CLL and indicate that both VEGF and Mcl-1 may prove to be useful therapeutic targets.

Research paper thumbnail of Variant IRF4/MUM1 associates with CD38 status and treatment-free survival in chronic lymphocytic leukaemia

Research paper thumbnail of Lycorine sensitizes CD40 ligand-protected chronic lymphocytic leukemia cells to bezafibrate- and medroxyprogesterone acetate-induced apoptosis but dasatanib does not overcome reported CD40-mediated drug resistance

Haematologica, 2010

Tumor cells in chronic lymphocytic leukemia accumulate in the periphery through the proliferation... more Tumor cells in chronic lymphocytic leukemia accumulate in the periphery through the proliferation of a minority of cells in lymph nodes. The proliferative and survival signals in these proliferation centers include interactions with T lymphocytes expressing CD40 ligand. We have demonstrated that the low toxicity combination of bezafibrate and medroxyprogesterone acetate induces mitochondrial superoxide-mediated apoptosis of non-CD40-liganded cells but not of cells exposed to CD40 ligand. Here, we assessed the ability of dasatinib and lycorine to restore bezafibrate-and medroxyprogesterone acetate-induced apoptosis in cells exposed to CD40 ligand. In parallel experiments we compared the ability of dasatinib to induce apoptosis of cells co-treated with fludarabine.