No description available.

Burkitt's lymphoma (BL) is a very aggressive, germinal center-derived B cell lymphoma. It mostly occurs in children from equatorial Africa who carry both the Epstein-Barr virus and the pathogens for malaria. Aside from this endemic form, there are also sporadic and immunosuppressive forms of BL. The most important characteristics are both the “starry sky” macrophages - from a histological point of view - and the translocation of MYC to one of the immunoglobulin enhancers at the molecular level. In addition to MYC overexpression several mutations, e.g. in p53 or cyclin D3, or constitutive active PI3-kinase signaling contribute to lymphoma genesis. Furthermore, NFAT factors seem also to play a crucial role. In human BL cell lines and murine Myc-driven tumors, the pro survival factor NFATc1 is highly expressed and present in the nuclei. To interfere with the NFAT pathway in lymphoma formation, I tested the “classical” way by inhibition of calcineurin (CN) with CsA, FK506 or VIVIT. Surprisingly, CN inhibition was not sufficient to induce a complete cytoplasmic translocation of NFATc1. Furthermore, CN inhibitors affected cellular survival and proliferation only at atypical high concentrations. Investigation of other pathways, like the PI3-kinase or JAK3, excluded the possibility that they promote NFATc1 activity. Finally, I treated NFATc1 over-expressing BL and pancreatic cancer cell lines with gallium nitrate that turned out to be a very potent inhibitor of cell survival. Gallium nitrate suppressed NFATc1 and MYC transcription though protein stability was not affected. Regarding the regulation of NFATc1 by MYC-overexpression, the data obtained in my work suggested that (1) NFATc1 mRNA level is down-regulated in murine cells, (2) NFATc1 protein level is up-regulated in both human and murine cells, and (3) MYC supports NFATc1’s nuclear residence. Finally, I discovered Myc-driven tumor cells as potential “starry sky” macrophages. Under certain conditions, mainly concerning calcium signaling, they change their outward appearance, surface marker expression, and gain the ability for phagocytosis. For the future, the discovery that gallium acts through NFATc1 in BL and probably numerous other cancer types opens up new strategies for therapeutic interventions. / Das Burkitt Lymphom (BL) ist ein sehr aggressives, aus dem Keimzentrum entsprungenes, B Zell Lymphom. Es tritt meisten in Kindern aus Äquatorialafrika auf, welche sowohl das EB-Virus als auch den Malariaerreger in sich tragen. Neben dieser endemischen Form gibt es auch eine sporadische und eine Immundefizienz-assozierte Form. Die wichtigsten Charakteristika sind aus Sicht der Histologie die "Sternenhimmelmakrophagen" und aus molekulargenetischer Sicht die Translokation des MYC-Onkogens in die Region eines Immunglobulingens. Zusätzlich zur MYC-Überexpression spielen viele weitere Mutationen, z. B. im p53 oder Cyclin D3 Gen, oder eine konstitutive PI3-Kinase eine wichtige Rolle in der Lymphomgenese. Des Weiteren spielen NFAT Faktoren eine wichtige Rolle: In BL Zelllinien und MYC-Tumoren aus der Maus sind die Überlebensfaktoren NFATc1 regelhaft vorhanden und im Zellkern, also in ihrer aktiven Form präsent. Um den NFAT Signalweg therapeutisch anzugehen, testete ich die "klassischen" Calcineurininhibitoren, wie CsA, FK506 und VIVIT. Überraschenderweise war eine Translokation von NFATc1 in das Zytoplasma nicht zu erreichen und nur atypisch hohe Konzentrationen der o.g. Wirkstoffe verhinderten das Wachstum der BL Zellen. Die Untersuchung anderer Signalwege, wie der PI3-Kinase- oder JAK3-Weg, zeigten keinen Einfluss auf NFATc1. Schlussendlich konnten BL-Zellen und Pankreaskarzinom-Zellen mit Galliumnitrat effektiv behandelt werden, welches sich als potentes Mittel herausstellte. Galliumnitrat unterdrückt dabei die Transkription von NFATc1 und MYC, wobei die Proteinstabilität unberührt bleibt. . MYC-Überexpression reguliert NFATc1 dahingehend, dass (1) NFATc1 mRNA Konzentrationen supprimiert werden (in Mauszellen), (2) NFATc1 Proteinkonzentrationen hochreguliert werden und (3) MYC die Kernlokalisation von NFATc1 unterstützt. Letztendlich konnte ich MYC-gesteuerte Tumorzellen als potenzielle "Sternenhimmelmakrophagen" entlarven: Unter bestimmten Umständen, hauptsächlich Kalzium- konzentrationen und signalwege betreffend, verändern sie ihr Aussehen, Oberflächenmarkerexpression und gewinnen die Fähigkeit zur Phagozytose. Zukünftig eröffnet die Entdeckung von Galliumsalzen als Krebstherapeutika und ihre Wirkung auf NFATc1 im Burkitt Lymphom weitere therapeutische Ansätze für zahlreiche weitere Tumorentitäten.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 6 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 1999. / Härtill 7 uppsatser.

Background: Burkitt lymphoma (BL) is a rare, highly aggressive B-cell malignancy treated most successfully with brief-duration, high-intensity chemotherapeutic regimens. The benefit of the addition of rituximab to these regimens remains uncertain. We sought to examine the effectiveness of chemotherapy with and without rituximab in patients with BL. Methods: This study is a retrospective cohort study of all adult patients with BL diagnosed and treated with modern, dose-intense chemotherapeutic regimens from 1998–2008 at two tertiary care institutions. All cases were confirmed by application of WHO 2008 criteria by hematopathologists. Medical records were reviewed for patient-, disease-, and treatment- related factors as well as treatment response and survival. Factors associated with survival were analyzed using Cox proportional hazards modeling. Results: A total of 35 patients were analyzed: 18 patients received rituximab with chemotherapy (R-chemo) and 17 received chemotherapy (chemo) alone. The median age was 42 (range 20–74 years); 57% were male; 71% had Ann Arbor Stage IV disease; 33% had central nervous system involvement; 78% had an Eastern Cooperative Oncology Group (ECOG) performance status of 0–1. R-chemo was associated with significantly longer overall survival (OS) than chemo alone (5-year OS 70% and 29%, respectively, p = 0.040). On multivariate regression analysis, poor performance status and central nervous system involvement were associated with poorer survival. The addition of rituximab to chemotherapy was associated with improved OS in patients with Burkitt lymphoma. Poor performance status and central nervous system involvement were prognostically significant on multivariate analysis.

Murine plasmacytoma models human cancers that involve deregulation of MYC. Overexpression and duplication of the immature colon carcinoma transcript 1 gene, Ict1, along with MYC deregulation may contribute to the aggressive mechanism for disease development in fast-onset mouse plasmacytomas. This study looks at Ict1 and c-MYC overexpression in mouse PreBmycER cells that serve as a cell culture model for MYC-dependent plasmacytomagenesis. An Ict1 inducible vector was transfected into the mouse PreBmycER cell line that contains inducible c-MYC. This allowed us to examine the effect of overexpression of ICT1 and c-MYC proteins simultaneously or each separately, on selected hallmark cancer cell traits such as increased proliferation, evasion of apoptosis and increased genomic instability. An increase in the number of cells in the S-phase was observed by 15 % and up to 20 % at 24 and 36 hours respectively, and cell doubling time shortened by almost 2 hours at 24 hours during peak ICT1 and c-MYC overexpression. Although, no noticeable change in apoptosis levels, or large scale genomic alterations were detected up to 96 hours post-ICT1 and c-MYC peak-overexpression, genomic instability was observed when MYC protein was overexpressed with or without ICT1 protein overexpression. Extrachromosomal elements increased in number and size during conditional MYC deregulation, and most of these elements (25 %) classified as Chromosome 11. These findings support Ict1 as a candidate gene that is selected for by MYC-deregulation during plasmacytomagenesis, and show promise that the experimental model of induced MYC and ICT1 overexpression in mouse PreB cells, deserves further investigation, specifically with in vivo studies. / October 2016

No description available.

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [85]-98).

Burkitt lymphoma is a highly aggressive B cell non-Hodgkin lymphoma characterized by the translocation t(8,14) and deregulation of the MYC gene on chromosome 8. The endemic (African) form presents classically as an expanding mass in the jaw. The nonendemic (European/North American) form often presents with an abdominal mass. We present an interesting case of Burkitt’s Lymphoma with atypical features. A thirty-five-year-old lady with no significant medical history presented to the hospital with a three week complaint of vaginal bleeding and lower abdominal pain/cramps associated with night sweats and chills. She underwent gynecologic workup with an ultrasound revealing endometrial thickening followed by a hysteroscopic Dilatation and Curettage procedure. Laboratory workup revealed direct hyperbilirubinemia and elevated liver enzymes. MRCP showed gallbladder wall thickening but no biliary obstruction. A diagnosis of acalculous cholecystitis was considered and she underwent a laproscopic cholecystectomy and liver biopsy. Her initial complete blood count revealed mild leukocytosis. Follow up lab work revealed worsening leukocytosis and a hematology consultation was sought. A peak WBC of 81,000 with peripheral blood blasts as high as 31% was noted. Peripheral smear exam revealed moderate sized immature wbc precursors/blasts with high nuclear-cytoplasmic ratio. Further hematological work up including bone marrow aspirate and biopsy was expedited. Pathology resulted positive for Burkitt's lymphoma/leukemia, positive molecular studies, t(8,14), involving bone marrow, gallbladder, liver and endometrium. Patient was emergently treated with dexamethasone and nitrogen mustard as elevated bilirubin levels precluded standard treatment. She was started on Rituxan as this neoplasm is a CD 20+ B cell malignancy but could not tolerate it. HyperCVAD multi-agent chemotherapy was subsequently initiated along with intrathecal chemotherapy (cytarabine and methotrexate). CSF cytology remained negative for lymphoma. Patient’s clinical condition has improved after 2 cycles of chemotherapy and she is currently receiving on going therapy. Burkitt’s lymphoma is one of the most aggressive neoplasms with a tumor doubling time of a few days. The usual presentation is with constitutional symptoms and adenopathy or a mass lesion, and sometimes may manifest solely in the peripheral circulation as an L3 variant of acute lymphoblastic leukemia. Hepatic parenchymal involvement is rare, but reported. Gallbladder involvement with endoluminal deposits is even rarer. Simultaneous hepatic, gallbladder, uterine, nodal and leukemic involvement at presentation is unique. Treatment is primarily with systemic chemotherapy and multi agent regimens effective in acute lymphoblastic leukemia and/or aggressive lymphomas have been used successfully in this condition with a complete response rate of 80%-90% with a long-term survival rate of approximately 60%. Therapy is fraught with risks of fatal tumor lysis syndrome, pancytopenia, infection/sepsis, and bleeding. Potential progression/relapse in the CNS with the CSF serving as a sanctuary site has been well documented necessitating prophylactic intra thecal chemotherapy administration as in our patient. Aggressive biology of this disease required urgent treatment, as delay in institution of combination chemotherapy could result in poor outcome. This case highlights the need to maintain an open mind while evaluating apparently routine symptoms and the importance of rapid diagnosis and treatment of a hematologic-oncologic emergency.

Background: We characterized B-cell non-Hodgkin lymphoma (NHL) cases over ten years at a tertiary children's hospital to contribute to the body of knowledge on pediatric lymphoma in developing countries with a high human immunodeficiency virus (HIV) burden. Methods: A retrospective cohort study using clinical and laboratory records of children newly diagnosed with B-cell NHL from January 2005 to December 2014. Results: Seventy-five children ≤ 15 years were included. The majority had Burkitt lymphoma (n = 61). Twenty-five percent (n = 19) were HIV positive and 16% (n = 12) had concurrent active tuberculosis. Bulky disease was present in 65.7% (n = 46) and 30.1% (n = 22) were classified as Lymphomes Malins B (LMB) risk group C. The five year survival estimates for HIV-negative and HIV-positive children were similar in our cohort: 81% vs. 79% for eventfree survival and 85% vs. 83.9% for overall survival. Of three children with Burkitt lymphoma, HIV and LMB group C, two died within one year. Conclusions: Irrespective of HIV status, the survival of children in our B-cell NHL cohort compares favorably with cure rates in developed nations, although advanced disease remains associated with a poor prognosis. Characterization of childhood NHL cases contributes to accurate risk stratification and tailored treatment.