1
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Bedier H, Theriault J, Conrad DM. A circulating proplatelet identified in an iron-deficient patient. Int J Lab Hematol 2024. [PMID: 38369894 DOI: 10.1111/ijlh.14247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 01/29/2024] [Indexed: 02/20/2024]
Affiliation(s)
- Helbies Bedier
- Division of Hematology, McGill University Health Centre, Montreal, Quebec, Canada
| | - Jessica Theriault
- Division of Hematopathology, QEII Health Sciences Centre, Halifax, Nova Scotia, Canada
| | - David M Conrad
- Division of Hematopathology, QEII Health Sciences Centre, Halifax, Nova Scotia, Canada
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2
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Conrad DM, Hilchie AL, McMillan KAM, Liwski RS, Hoskin DW, Power Coombs MR. The Acute Phase Protein Hepcidin Is Cytotoxic to Human and Mouse Myeloma Cells. Anticancer Res 2021; 41:601-608. [PMID: 33517264 DOI: 10.21873/anticanres.14811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 01/04/2021] [Accepted: 01/07/2021] [Indexed: 11/10/2022]
Abstract
BACKGROUND/AIM Hepcidin is a cationic acute phase reactant synthesized by the liver. It has bactericidal properties and is a major regulator of iron homeostasis. Cationic antimicrobial peptides represent an innate antimicrobial defense system. We hypothesized that, like other cationic antimicrobial peptides, hepcidin is cytotoxic to cancer cells. MATERIALS AND METHODS The cytotoxicity of human hepcidin against myeloma cells was assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and DNA fragmentation assays. Plasma membrane damage was quantified by propidium iodide (PI) staining. Cell membrane changes were visualized by scanning electron microscopy. RESULTS Hepcidin impaired myeloma cell survival and induced DNA fragmentation. PI staining and scanning electron microscopy revealed hepcidin-induced disruption of the plasma membrane. CONCLUSION Human hepcidin is an anti-cancer peptide that induces myeloma cell lysis, and therefore may play a role in innate anticancer immunity. To our knowledge, this is the first biological function ascribed to human hepcidin that is not related to its antimicrobial and iron-regulatory properties.
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Affiliation(s)
- David M Conrad
- Department of Pathology & Laboratory Medicine, Division of Hematopathology, Queen Elizabeth II Health Sciences Centre, Halifax, NS, Canada.,Department of Pathology, Dalhousie University, Halifax, NS, Canada.,Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada
| | | | | | - Robert S Liwski
- Department of Pathology & Laboratory Medicine, Division of Hematopathology, Queen Elizabeth II Health Sciences Centre, Halifax, NS, Canada.,Department of Pathology, Dalhousie University, Halifax, NS, Canada.,Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada
| | - David W Hoskin
- Department of Pathology, Dalhousie University, Halifax, NS, Canada.,Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada.,Department of Surgery, Dalhousie University, Halifax, NS, Canada
| | - Melanie R Power Coombs
- Department of Pathology, Dalhousie University, Halifax, NS, Canada.,Biology Department, Acadia University, Wolfville, NS, Canada
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3
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Nix KM, Harrison KJ, Shivakumar SP, Shawwa AA, Conrad DM. Mixed phenotype acute leukemia, B/myeloid, NOS with near-tetraploidy: a case report. Int J Clin Exp Pathol 2017; 10:11206-11210. [PMID: 31966471 PMCID: PMC6965837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 05/20/2017] [Indexed: 06/10/2023]
Abstract
Acute leukemia in adults is usually associated with a myeloid phenotype, and less commonly presents as an acute lymphocytic leukemia. Rarely, the leukemic blast cells express more than one lineage phenotype and satisfy the diagnostic criteria for an acute leukemia of ambiguous lineage (ALAL), further subclassified as mixed phenotype acute leukemia (MPAL). Near-tetraploidy is an unusual presentation of acute leukemia where the blasts contain 80-104 chromosomes. More commonly associated with acute lymphocytic leukemia, near-tetraploidy has been described in only a limited number of cases of acute myeloid leukemias, and near-tetraploid ALAL is rare. We describe the first report of near-tetraploid MPAL, B/myeloid, not otherwise specified.
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Affiliation(s)
- Kimberley M Nix
- Department of Medicine, Dalhousie UniversityHalifax, Nova Scotia, Canada
| | - Karen J Harrison
- Department of Pathology and Laboratory Medicine, Dalhousie UniversityHalifax, Nova Scotia, Canada
- IWK Health CentreHalifax, Nova Scotia, Canada
| | - Sudeep P Shivakumar
- Department of Medicine, Dalhousie UniversityHalifax, Nova Scotia, Canada
- QEII Health Sciences CentreHalifax, Nova Scotia, Canada
| | - Allam A Shawwa
- Department of Pathology and Laboratory Medicine, Dalhousie UniversityHalifax, Nova Scotia, Canada
- QEII Health Sciences CentreHalifax, Nova Scotia, Canada
| | - David M Conrad
- Department of Pathology and Laboratory Medicine, Dalhousie UniversityHalifax, Nova Scotia, Canada
- QEII Health Sciences CentreHalifax, Nova Scotia, Canada
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4
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Quinn JG, Conrad DM, Cheng CK. Process mining is an underutilized clinical research tool in transfusion medicine. Transfusion 2017; 57:501-503. [PMID: 28164303 DOI: 10.1111/trf.13995] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 11/29/2016] [Accepted: 11/29/2016] [Indexed: 11/28/2022]
Abstract
BACKGROUND To understand inventory performance, transfusion services commonly use key performance indicators (KPIs) as summary descriptors of inventory efficiency that are graphed, trended, and used to benchmark institutions. STUDY DESIGN AND METHODS Here, we summarize current limitations in KPI-based evaluation of blood bank inventory efficiency and propose process mining as an ideal methodology for application to inventory management research to improve inventory flows and performance. RESULTS The transit of a blood product from inventory receipt to final disposition is complex and relates to many internal and external influences, and KPIs may be inadequate to fully understand the complexity of the blood supply chain and how units interact with its processes. Process mining lends itself well to analysis of blood bank inventories, and modern laboratory information systems can track nearly all of the complex processes that occur in the blood bank. CONCLUSION Process mining is an analytical tool already used in other industries and can be applied to blood bank inventory management and research through laboratory information systems data using commercial applications. Although the current understanding of real blood bank inventories is value-centric through KPIs, it potentially can be understood from a process-centric lens using process mining.
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Affiliation(s)
- Jason G Quinn
- Department of Pathology and Laboratory Medicine, Division of Hematopathology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - David M Conrad
- Department of Pathology and Laboratory Medicine, Division of Hematopathology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Calvino K Cheng
- Department of Pathology and Laboratory Medicine, Division of Hematopathology, Dalhousie University, Halifax, Nova Scotia, Canada
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5
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Gallivan CD, Conrad DM, Kew AK. A case of congenital TTP presenting with microganiopathy in adulthood. BMC Hematol 2014; 14:16. [PMID: 25243071 PMCID: PMC4168056 DOI: 10.1186/2052-1839-14-16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Accepted: 09/10/2014] [Indexed: 12/02/2022]
Abstract
Background Congenital thrombotic thrombocytopenic purpura (TTP), also known as Upshaw-Schulman Syndrome is a rare inherited deficiency of ADAMTS13. Unlike the more common acquired TTP which is characterized by an acquired inhibitor of ADAMTS13, patients with congenital TTP have an absolute deficiency of ADAMTS13 without an inhibitor. Congenital TTP generally presents in infancy with repeat episodes of acute hemolysis and evidence of microangiopathy, these episodes are usually triggered by illness or physiological stress. Congenital TTP can be effectively treated with plasma infusion either during acute episodes or on a prophylactic schedule to prevent episodes. Case presentation We present a case of a 25 year old Caucasian woman with no know family history of hematological disorders with congenital TTP. She presented with episodes of hemolysis since infancy, but without clear evidence of microangiopathy until the age of 25. At presentation to our center the patient was documented to have thrombocytopenia, elevated creatinine, and schistocytes. She was initially treated with plasma infusion at a rate of 60 ml/hr continuously for a 24 hr period with resolution of her thrombocytopenia and hemolysis. At the time of writing this article she is maintained on a prophylactic schedule of biweekly plasma infusions at 10 mg/kg and is maintaining a normal platelet count with no evidence of hemolysis. Conclusion Congenital TTP is a rare condition, and the above case is atypical as the patient did not present with clear evidence of microangiopathy until adulthood. Although this a rare condition it is important for physicians to be aware of as it, especially the possibility of atypical presentations, as the condition is potentially fatal and effective treatment exists.
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Affiliation(s)
- Chris D Gallivan
- Department of Medicine, Division of Hematology, Division of Hematopathology, Queen Elizabeth II Health Sciences Centre, Capital District Health, Authority and Dalhousie University, Halifax, Nova Scotia Canada
| | - David M Conrad
- Department of Pathology and Laboratory Medicine, Division of Hematopathology, Queen Elizabeth II Health Sciences Centre, Capital District Health, Authority and Dalhousie University, Halifax, Nova Scotia Canada
| | - Andrea K Kew
- Department of Medicine, Division of Hematology, Division of Hematopathology, Queen Elizabeth II Health Sciences Centre, Capital District Health, Authority and Dalhousie University, Halifax, Nova Scotia Canada
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6
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Hilchie AL, Conrad DM, Coombs MRP, Zemlak T, Doucette CD, Liwski RS, Hoskin DW. Pleurocidin-family cationic antimicrobial peptides mediate lysis of multiple myeloma cells and impair the growth of multiple myeloma xenografts. Leuk Lymphoma 2013; 54:2255-62. [PMID: 23350892 DOI: 10.3109/10428194.2013.770847] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Abstract Multiple myeloma is a common hematological malignancy that urgently requires new approaches to treatment, since the disease is not curable using current chemotherapeutic regimens. The aim of this study was to determine whether human and mouse multiple myeloma cells are killed by the pleurocidin-like cationic antimicrobial peptides NRC-03 and NRC-07, previously shown to be active against breast cancer cells. We demonstrate here that NRC-03 and NRC-07 bound to and rapidly killed multiple myeloma cells by causing extensive membrane damage, as well as DNA cleavage. NRC-03 showed greater binding to multiple myeloma cells and a more potent cytotoxic effect than NRC-07. In addition, intratumoral injections of NRC-03 impaired the growth of multiple myeloma xenografts in immune-deficient mice. We conclude that NRC-03 warrants further investigation for its possible use in the treatment of multiple myeloma.
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7
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Forward NA, Conrad DM, Power Coombs MR, Doucette CD, Furlong SJ, Lin TJ, Hoskin DW. Curcumin blocks interleukin (IL)-2 signaling in T-lymphocytes by inhibiting IL-2 synthesis, CD25 expression, and IL-2 receptor signaling. Biochem Biophys Res Commun 2011; 407:801-6. [DOI: 10.1016/j.bbrc.2011.03.103] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 03/23/2011] [Indexed: 12/11/2022]
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8
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Conrad DM, Furlong SJ, Doucette CD, West KA, Hoskin DW. The Ca(2+) channel blocker flunarizine induces caspase-10-dependent apoptosis in Jurkat T-leukemia cells. Apoptosis 2010; 15:597-607. [PMID: 20094800 DOI: 10.1007/s10495-010-0454-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Flunarizine is a Ca(2+) channel blocker that can be either cytoprotective or cytotoxic, depending on the cell type that is being examined. We show here that flunarizine was cytotoxic for Jurkat T-leukemia cells, as well as for other hematological maligancies, but not for breast or colon carcinoma cells. Treatment of Jurkat cells with flunarizine resulted in caspase-3 activation, poly (ADP-ribose) polymerase cleavage, and laddering of DNA fragments, all of which are hallmarks of apoptosis. Flunarizine-induced DNA fragmentation was inhibited by the caspase-3 inhibitor z-DEVD-fmk, the caspase-8/caspase-10 inhibitor z-IETD-fmk, and the caspase-10 inhibitor z-AEVD-fmk, but was not reduced in caspase-8-deficient Jurkat cells, indicating the involvement of caspase-10 upstream of caspase-3 activation. Interestingly, FADD recruitment to a death receptor was not involved since flunarizine caused DNA fragmentation in FADD-deficient Jurkat cells. Flunarizine treatment of Jurkat cells also resulted in reactive oxygen species production, dissipation of mitochondrial transmembrane potential, release of cytochrome c from mitochondria, and caspase-9 activation, although none of these events were necessary for apoptosis induction. Collectively, these findings indicate that flunarizine triggers apoptosis in Jurkat cells via FADD-independent activation of caspase-10. Flunarizine warrants further investigation as a potential anti-cancer agent for the treatment of hematological malignancies.
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Affiliation(s)
- David M Conrad
- Department of Microbiology & Immunology, Dalhousie University, Halifax, Nova Scotia, B3H 1X5, Canada
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9
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Conrad DM, Furlong SJ, Doucette CD, Boudreau RT, Hoskin DW. Role of mitogen-activated protein kinases in Thy-1-induced T-lymphocyte activation. Cell Signal 2009; 21:1298-307. [DOI: 10.1016/j.cellsig.2009.03.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 03/03/2009] [Accepted: 03/16/2009] [Indexed: 11/17/2022]
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10
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Bezuhly M, Howlett A, Colp P, Conrad DM, Walsh N, Rowden G, Morris SF, Langley RG. Quantitative HLA-G expression in metastasising and non-metastasising primary thin cutaneous melanomas. Dermatology 2008; 217:281-3. [PMID: 18688170 DOI: 10.1159/000150602] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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11
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Conrad DM, Robichaud MRJ, Mader JS, Boudreau RTM, Richardson AM, Giacomantonio CA, Hoskin DW. 2-Chloro-2'-deoxyadenosine-induced apoptosis in T leukemia cells is mediated via a caspase-3-dependent mitochondrial feedback amplification loop. Int J Oncol 2008; 32:1325-33. [PMID: 18497995 DOI: 10.3892/ijo_32_6_1325] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
2-Chloro-2'-deoxyadenosine (CdA; cladribine) is a chemotherapeutic agent used in the treatment of certain leukemias. However, the signalling events that govern CdA-mediated cytotoxicity in leukemia cells remain unclear. We show here that CdA treatment caused Jurkat human T leukemia cells to die via apoptosis in a dose- and time-dependent fashion. Bcl-2 overexpression protected Jurkat T leukemia cells from CdA-induced apoptosis and loss of mitochondrial transmembrane potential (Delta Psi m). Furthermore, mitochondria that were isolated from Jurkat T leukemia cells and then exposed to CdA showed a loss of Delta Psi m, indicating that CdA directly compromised outer mitochondrial membrane integrity. CdA treatment of Jurkat T leukemia cells resulted in the activation of caspase-3, -8, and -9, while inhibition of these caspases prevented the CdA-induced loss of Delta Psi m, as well as DNA fragmentation. In addition, caspase-3 inhibition prevented caspase-8 activation while caspase-8 inhibition prevented caspase-9 activation. Death receptor signalling was not involved in CdA-induced apoptosis since cytotoxicity was not affected by FADD-deficiency or antibody neutralization of either Fas ligand or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Taken together, these data suggested that CdA-induced apoptosis in Jurkat T leukemia cells was mediated via a caspase-3-dependent mitochondrial feedback amplification loop. CdA treatment also increased p38 mitogen-activated protein (MAPK) and extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation in Jurkat T leukemia cells. Although ERK1/2 inhibition did not affect CdA-mediated cytotoxicity, inhibition of p38 MAPK had an enhancing effect, which suggested a cytoprotective function for p38 MAPK. Agents that inhibit p38 MAPK might therefore increase the effectiveness of CdA-based chemotherapy.
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Affiliation(s)
- David M Conrad
- Department of Microbiology & Immunology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, B3H 1X5, Canada
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12
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Hoskin DW, Mader JS, Furlong SJ, Conrad DM, Blay J. Inhibition of T cell and natural killer cell function by adenosine and its contribution to immune evasion by tumor cells (Review). Int J Oncol 2008. [PMID: 18292929 DOI: 10.3892/ijo.32.3.527] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The resistance of many human cancers to immune-based therapies, including adoptive immunotherapy and the administration of therapeutic cancer vaccines, has been attributed to tumor-associated immune suppression, due in part to immunosuppressive molecules located within the tumor microenvironment. Adenosine is a purine nucleoside found within the interstitial fluid of solid tumors at concentrations that are able to inhibit cell-mediated immune responses to tumor cells. It is well established that extracellular adenosine inhibits T lymphocyte activation and effector function, including T cell adhesion to tumor cells and cytotoxic activity, by signaling primarily through A2a and A3 adenosine receptors on the surface of T cells. Importantly, A2a adenosine receptor-deficient mice exhibit enhanced anti-tumor immune responses by CD8+ T cells, as well as a dramatic reduction in the growth of experimental tumors in comparison to wild-type controls. A2a adenosine receptor signaling has also been implicated in adenosine-mediated inhibition of cytokine production and cytotoxic activity by activated natural killer (NK) cells, although the process of NK cell granule exocytosis is apparently suppressed via a distinct and as yet uncharacterized adenosine receptor. In this report, we review the evidence that adenosine is a potent inhibitor of cellular immune responses and may therefore be a major barrier to the successful immunotherapy of human carcinomas. The signaling pathways through which adenosine exerts its inhibitory effects on cell-mediated immune responses are also discussed. The accumulated evidence suggests that the effectiveness of immune-based therapies for solid tumors may be enhanced by selective antagonism of the adenosine receptor subtypes through which adenosine inhibits the anti-tumor activity of T lymphocytes and NK cells.
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Affiliation(s)
- David W Hoskin
- Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada.
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13
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Boudreau RTM, Conrad DM, Hoskin DW. Differential involvement of reactive oxygen species in apoptosis caused by the inhibition of protein phosphatase 2A in Jurkat and CCRF-CEM human T-leukemia cells. Exp Mol Pathol 2007; 83:347-56. [PMID: 17936751 DOI: 10.1016/j.yexmp.2007.09.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2007] [Accepted: 09/14/2007] [Indexed: 12/16/2022]
Abstract
A better understanding of dysregulated signaling pathways in cancer cells may suggest novel strategies to prevent tumor development and/or progression. Here we show that Jurkat and CCRF-CEM human T-leukemia cell lines were more sensitive than normal human T cells to the cytotoxic effect of inhibiting protein phosphatase 2A (PP2A). Inhibition of PP2A by okadaic acid (OA) caused T-leukemia cells to die by apoptosis, as indicated by DNA fragmentation, caspase-3 activation, loss of mitochondrial membrane potential (DeltaPsi(m)), and changes in nuclear morphology that were consistent with apoptosis. PP2A might therefore be a useful intracellular target for the treatment of T cell-derived leukemias. We also observed that reactive oxygen species (ROS) were generated in response to PP2A inhibition in T-leukemia cells. However, loss of DeltaPsi(m) that resulted from PP2A inhibition was not prevented by exogenous antioxidants (glutathione and N-acetyl-cysteine), indicating that OA-induced changes in mitochondrial membrane permeability were not a consequence of ROS production. Moreover, exogenous antioxidants protected CCRF-CEM T-leukemia cells from apoptosis caused by PP2A inhibition but failed to prevent OA-induced apoptosis in Jurkat T-leukemia cells, indicating a differential role for ROS in apoptosis caused by PP2A inhibition in two different human T-leukemia cell lines.
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Affiliation(s)
- Robert T M Boudreau
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada B3H 1X5
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14
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Boudreau RTM, Conrad DM, Hoskin DW. Apoptosis induced by protein phosphatase 2A (PP2A) inhibition in T leukemia cells is negatively regulated by PP2A-associated p38 mitogen-activated protein kinase. Cell Signal 2007; 19:139-51. [PMID: 16844342 DOI: 10.1016/j.cellsig.2006.05.030] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Revised: 05/29/2006] [Accepted: 05/31/2006] [Indexed: 01/21/2023]
Abstract
Serine/threonine phosphatase regulation of phosphorylation-mediated intracellular signaling controls a number of important processes in mammalian cells. In this study, we show that constitutively active protein phosphatase 2A (PP2A), which is a serine/threonine phosphatase, is essential for T leukemia cell survival. Jurkat and CCRF-CEM T leukemia cells treated with the PP2A-selective inhibitor okadaic acid (OA) showed a dose- and time-dependent induction of apoptosis, as indicated by loss of mitochondrial transmembrane potential (delta psi(m)), cleavage-induced activation of caspase-3, -8, and -9, and DNA fragmentation. In addition, caspase-8 or caspase-9 inhibition with z-IETD-fmk or z-LEHD-fmk, respectively, largely prevented OA-induced apoptosis. Although OA treatment did not affect constitutive Bcl-2 expression, overexpression of Bcl-2 prevented both OA-induced DNA fragmentation and dissipation of delta psi(m). Furthermore, inhibition of caspase-3, -8, or -9 partially protected against OA-induced loss of delta psi(m). In addition, caspase-9 and caspase-3 inhibition largely prevented procaspase-3 and procaspase-8 cleavage, respectively, while caspase-8 inhibition partially interfered with procaspase-9 cleavage in OA-treated T leukemia cells. Thus, PP2A inhibition triggered the intrinsic pathway of apoptosis, which was enhanced by a mitochondrial feedback amplification loop. PP2A has also been implicated in the regulation of p38 mitogen-activated protein kinase (MAPK). Co-immunoprecipitation analysis revealed a physical association between the catalytic subunit of PP2A and p38 MAPK in T leukemia cells. Moreover, OA treatment caused p38 MAPK to be phosphorylated in a dose- and time-dependent fashion, indicating that PP2A prevented p38 MAPK activation. Although p38 MAPK activation usually promotes apoptosis, pharmacologic inhibition of p38 MAPK exacerbated OA-induced DNA fragmentation and loss of delta psi(m) in T leukemia cells, suggesting that, in this instance, the p38 MAPK signaling pathway promoted cell survival. Collectively, these findings indicate that PP2A and p38 MAPK have coordinate effects on signaling pathways that regulate the survival of T leukemia cells.
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Affiliation(s)
- Robert T M Boudreau
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University, Sir Charles Tupper Medical Building, 5850 University Ave., Halifax, Nova Scotia, Canada B3H 1X5
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15
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Haeryfar SMM, Conrad DM, Musgrave B, Hoskin DW. Antibody blockade of Thy-1 (CD90) impairs mouse cytotoxic T lymphocyte induction by anti-CD3 monoclonal antibody. Immunol Cell Biol 2005; 83:352-63. [PMID: 16033530 DOI: 10.1111/j.1440-1711.2005.01342.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thy-1 (CD90) expressed by mouse T cells is known to have signal transducing properties, but the ability of Thy-1 to enhance cytotoxic T lymphocyte (CTL) development is not well understood. Here we show that stimulation of mouse T cells with monoclonal antibodies (mAb) to CD3, CD28 and Thy-1 (clone G7), which were coimmobilized on polystyrene microbeads, resulted in a greater proliferative response than stimulation with only anti-CD3 and anti-CD28 mAb, indicating that Thy-1 cross-linking enhanced T cell receptor/CD28-driven T cell activation. Consistent with this finding, Thy-1 blockade with a soluble nonactivating anti-Thy-1 mAb (clone 30-H12) inhibited anti-CD3-induced proliferation of CD4+ and CD8+ T cells, and the induction of cytotoxic effector cells in a dose-dependent fashion. Interleukin-2 synthesis and CD25 expression were also impaired by Thy-1 blockade. The inhibitory effect involved a defect at or before the level of protein kinase C activation because the addition of phorbol ester ablated the anti-Thy-1-mediated inhibition of anti-CD3-induced T cell activation. The CTL that were induced in the presence of blocking anti-Thy-1 mAb adhered to target cells but showed reduced expression of granzyme B and perforin. In contrast, Fas ligand expression and function was not affected by Thy-1 blockade. We conclude that Thy-1 signalling promotes the in vitro generation of CTL that kill in a granule-dependent fashion.
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MESH Headings
- Animals
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/pharmacology
- Antigens, Differentiation/genetics
- CD3 Complex/immunology
- Cell Proliferation/drug effects
- Endopeptidases/genetics
- Gene Expression Regulation/drug effects
- Granzymes
- Interleukin-2/genetics
- Interleukin-2/pharmacology
- Membrane Proteins/genetics
- Mice
- Mice, Inbred C57BL
- Pore Forming Cytotoxic Proteins
- Protein Kinase C/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Interleukin-2/metabolism
- T-Lymphocytes, Cytotoxic/cytology
- T-Lymphocytes, Cytotoxic/drug effects
- T-Lymphocytes, Cytotoxic/immunology
- T-Lymphocytes, Cytotoxic/metabolism
- Thy-1 Antigens/immunology
- Thy-1 Antigens/metabolism
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Affiliation(s)
- S M Mansour Haeryfar
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University, Halifax, Canada
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16
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El-Darahali A, Fawcett H, Mader JS, Conrad DM, Hoskin DW. Adenosine-induced apoptosis in EL-4 thymoma cells is caspase-independent and mediated through a non-classical adenosine receptor. Exp Mol Pathol 2005; 79:249-58. [PMID: 16168410 DOI: 10.1016/j.yexmp.2005.08.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Accepted: 08/01/2005] [Indexed: 12/01/2022]
Abstract
Cell death caused by the accumulation of extracellular adenosine is believed to contribute to the profound loss of T lymphocytes in patients with severe combined immunodeficiency disease due to adenosine deaminase deficiency. Although adenosine is known to trigger apoptosis in thymocytes and peripheral T cells, the molecular basis of this effect is not understood. In this study, we show that adenosine-induced apoptosis in mouse EL-4 thymoma cells was associated with the generation of reactive oxygen species and a reduction in mitochondrial transmembrane potential. In addition, cell death was by a caspase-independent mechanism because caspase inhibitors did not protect EL-4 cells from adenosine-induced cytotoxicity. Although reverse transcriptase polymerase chain reaction revealed that EL-4 cells expressed A2b and A3 adenosine receptor subtypes, blockade of A2b and A3 adenosine receptors with receptor-selective antagonists did not attenuate adenosine-induced cell death. Nevertheless, the failure of nucleoside transport inhibitors to prevent adenosine cytotoxicity suggested that adenosine was acting through a cell-surface receptor. In addition, adenosine-induced apoptosis was not due to an accumulation of intracellular cyclic adenosine monophosphate (cAMP) since neither forskolin nor 8-Br-cAMP was cytotoxic for EL-4 cells. Adenosine therefore acts through a non-classical receptor at the cell surface to trigger caspase-independent apoptosis in mouse thymoma cells.
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Affiliation(s)
- Asile El-Darahali
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
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17
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Abstract
Bovine lactoferricin (LfcinB) is a cationic, amphipathic peptide that is cytotoxic for human and rodent cancer cells. However, the mechanism by which LfcinB causes the death of cancer cells is not well understood. Here, we show that in vitro treatment with LfcinB rapidly induced apoptosis in several different human leukemia and carcinoma cell lines as determined by DNA fragmentation assays and phosphatidylserine headgroup inversion detected by Annexin V binding to the surface of cancer cells. Importantly, LfcinB treatment did not adversely affect the viability of untransformed human lymphocytes, fibroblasts, or endothelial cells. Studies with different LfcinB-derived peptide fragments revealed that the cytotoxic activity of LfcinB resided within the amino acid sequence FKCRRWQWRM. Treatment of Jurkat T leukemia cells with LfcinB resulted in the production of reactive oxygen species followed by caspase-2-induced dissipation of mitochondrial transmembrane potential and subsequent activation of caspase-9 and caspase-3. Selective inhibitors of caspase-2 (Z-VDVAD-FMK), caspase-9 (Z-LEHD-FMK), and caspase-3 (Z-DEVD-FMK) protected both leukemia and carcinoma cells from LfcinB-induced apoptosis. Conversely, a caspase-8 inhibitor (Z-IETD-FMK) had no effect, which argued against a role for caspase-8 and was consistent with the finding that death receptors were not involved in LfcinB-induced apoptosis. Furthermore, Jurkat T leukemia cells that overexpressed Bcl-2 were less sensitive to LfcinB-induced apoptosis, which was characterized by mitochondrial swelling and the release of cytochrome c from mitochondria into the cytosolic compartment. We conclude that LfcinB kills cancer cells by triggering the mitochondrial pathway of apoptosis at least in part through the generation of reactive oxygen species.
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Affiliation(s)
- Jamie S Mader
- Department of Pathology, Faculty of Medicine, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova Scotia, Canada B3H 1X5
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18
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Conrad DM, Hanniman EA, Watson CL, Mader JS, Hoskin DW. Ryanodine receptor signaling is required for anti-CD3-induced T cell proliferation, interleukin-2 synthesis, and interleukin-2 receptor signaling. J Cell Biochem 2005; 92:387-99. [PMID: 15108363 DOI: 10.1002/jcb.20064] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Ryanodine receptors (RyR) are involved in regulating intracellular Ca(++) mobilization in T lymphocytes. However, the importance of RyR signaling during T cell activation has not yet been determined. In this study, we have used the RyR-selective antagonists, ruthenium red and dantrolene, to determine the effect of RyR blockade on T cell receptor-mediated activation events and cytokine-dependent T cell proliferation. Both ruthenium red and dantrolene inhibited DNA synthesis and cell division, as well as the synthesis of interleukin (IL)-2 by T lymphocytes responding to mitogenic anti-CD3 antibody. Blockade of RyR at initiation of culture or as late as 24 h after T cell receptor stimulation inhibited T cell proliferation, suggesting a requirement for sustained RyR signaling during cell cycle progression. Although flow cytometry revealed that RyR blockade had little effect on activation-induced expression of the alpha chain (CD25) of the high affinity IL-2 receptor, the inhibitory effect of RyR antagonists could not be reversed by the addition of exogenous IL-2 at initiation of culture. In addition, both ruthenium red and dantrolene had a strong inhibitory effect on IL-2-dependent proliferation of CTLL-2 T cells. These data indicate that RyR are involved in regulating IL-2 receptor signaling that drives T cell progression through the cell cycle. We conclude that RyR-associated Ca(++) signaling regulates T cell proliferation by promoting both IL-2 synthesis and IL-2-dependent cell cycle progression.
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Affiliation(s)
- David M Conrad
- Department of Microbiology & Immunology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, B3H 1X5 Canada
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19
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Zhang H, Conrad DM, Butler JJ, Zhao C, Blay J, Hoskin DW. Adenosine acts through A2 receptors to inhibit IL-2-induced tyrosine phosphorylation of STAT5 in T lymphocytes: role of cyclic adenosine 3',5'-monophosphate and phosphatases. J Immunol 2004; 173:932-44. [PMID: 15240680 DOI: 10.4049/jimmunol.173.2.932] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Adenosine is a purine nucleoside with immunosuppressive activity that acts through cell surface receptors (A(1), A(2a), A(2b), A(3)) on responsive cells such as T lymphocytes. IL-2 is a major T cell growth and survival factor that is responsible for inducing Jak1, Jak3, and STAT5 phosphorylation, as well as causing STAT5 to translocate to the nucleus and bind regulatory elements in the genome. In this study, we show that adenosine suppressed IL-2-dependent proliferation of CTLL-2 T cells by inhibiting STAT5a/b tyrosine phosphorylation that is associated with IL-2R signaling without affecting IL-2-induced phosphorylation of Jak1 or Jak3. The inhibitory effect of adenosine on IL-2-induced STAT5a/b tyrosine phosphorylation was reversed by the protein tyrosine phosphatase inhibitors sodium orthovanadate and bpV(phen). Adenosine dramatically increased Src homology region 2 domain-containing phosphatase-2 (SHP-2) tyrosine phosphorylation and its association with STAT5 in IL-2-stimulated CTLL-2 T cells, implicating SHP-2 in adenosine-induced STAT5a/b dephosphorylation. The inhibitory effect of adenosine on IL-2-induced STAT5a/b tyrosine phosphorylation was reproduced by A(2) receptor agonists and was blocked by selective A(2a) and A(2b) receptor antagonists, indicating that adenosine was mediating its effect through A(2) receptors. Inhibition of STAT5a/b phosphorylation was reproduced with cell-permeable 8-bromo-cAMP or forskolin-induced activation of adenylyl cyclase, and blocked by the cAMP/protein kinase A inhibitor Rp-cAMP. Forskolin and 8-bromo-cAMP also induced SHP-2 tyrosine phosphorylation. Collectively, these findings suggest that adenosine acts through A(2) receptors and associated cAMP/protein kinase A-dependent signaling pathways to activate SHP-2 and cause STAT5 dephosphorylation that results in reduced IL-2R signaling in T cells.
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Affiliation(s)
- Hong Zhang
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
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20
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Hurt GJ, McQuellon RP, Michielutte R, Conrad DM, Carter S, Anderson H. Risk assessment of first-degree relatives of women with breast cancer: a feasibility study. Oncol Nurs Forum 2001; 28:1097-104. [PMID: 11517843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
PURPOSE/OBJECTIVES To measure psychological distress and test the feasibility of a psychological intervention to reduce distress in patients undergoing risk assessment. DESIGN Descriptive. SETTING A comprehensive cancer center located in the southeastern United States. SAMPLE 20 first-degree relatives of women diagnosed with breast cancer (X age = 42; range = 21-70) completed the risk assessment process. Three were lost to follow-up at three months, leaving a total of 17 evaluable patients. METHODS Data collection was by means of family/medical history forms and questionnaires administered at baseline and one and three months. Participants were randomized to either a control group consisting of standard education about risk for breast cancer or to an intervention group consisting of standard education plus a psychological intervention designed to teach stress-management skills. MAIN RESEARCH VARIABLES Psychological distress, depressive symptoms, intrusive thoughts about breast cancer, and perceived risk for developing breast cancer. FINDINGS Delivery of a psychological intervention proved feasible. Although no statistically significant differences existed between the intervention and control groups on distress and depressive symptoms, the intervention group reported fewer intrusive thoughts about breast cancer at follow-up. Risk did not predict anxiety levels. A large majority (73%) of the women overestimated the risk of breast cancer at baseline. CONCLUSIONS This study demonstrated the feasibility of a multidisciplinary team approach to breast cancer risk assessment and counseling and management of psychological distress in first-degree relatives of women with breast cancer. The data suggest that a psychological intervention may reduce cancer-specific psychological distress in women at increased risk for breast cancer. IMPLICATIONS FOR NURSING PRACTICE Oncology nurses can play an important role in the delivery of interventions to educate and reduce distress in women undergoing breast cancer risk assessment.
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Affiliation(s)
- G J Hurt
- Cancer Patient Support Program, Comprehensive Cancer Center, School of Medicine, Wake Forest University, Winston-Salem, NC, USA
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