[Show abstract][Hide abstract] ABSTRACT: The Epstein-Barr virus (EBV) infects most of the world's adult population. In most cases primary infection and virus persistence are asymptomatic, the virus having evolved a sophisticated strategy to exist long-term in the B cell pool. However, EBV can contribute to the development of several human B-cell lymphomas, which include Hodgkin's lymphoma (HL), Burkitt's lymphoma, and a subset of diffuse large B cell lymphomas. EBV potently transforms resting B cells in vitro (Young & Murray, 2003; Young & Rickinson, 2004; Oyama et al., 2003; Oyama et al., 2007). Two questions central to our understanding of the origins of EBV-associated B cell lymphomas are; 1) how the host and virus interact to allow benign persistent latent infection, and 2) how perturbation of this normal homeostasis leads to neoplastic transformation. This review will summarise current knowledge of how the EBV life cycle is regulated in the B cells of the asymptomatic host. It will also discuss how the disruption of normal B cell homeostasis can contribute to the development of B cell lymphomas, focussing on several novel pathogenic mechanisms in EBV-associated HL which include the suppression of the virus lytic cycle and the activation of collagen receptor signalling.
Journal of General Virology 06/2014; · 3.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mutations of nucleophosmin 1 are frequently found in acute myeloid leukemia and lead to aberrant cytoplasmic accumulation of nucleophosmin protein. Immunohistochemical staining is therefore recommended as technique of choice in front-line screening. In this study, we assessed the sensitivity and specificity of immunohistochemistry on formalin fixed bone marrow biopsies compared with gold standard molecular analysis to predict nucleophosmin 1 mutation status in 119 acute myeloid leukemia patients. Discrepant cases were further characterized by gene expression analyses and fluorescence in situ hybridization. A large overlap between both methods was observed. Nevertheless, nine patients demonstrated discordant results at initial screening. Five cases demonstrated nuclear staining of nucleophosmin 1 by immunohistochemistry, but an nucleophosmin 1 mutation by molecular analysis. In three cases this could be contributed to technical issues and in two cases minor subpopulations of myeloblasts had been discovered initially. All tested cases exhibited the characteristic nucleophosmin-mutated gene expression pattern. Four cases had cytoplasmic nucleophosmin 1 staining and an nucleophosmin-mutated gene expression pattern without a detectable nucleophosmin 1 mutation. In two of these cases we found the chromosomal translocation t(3;5)(q25;q35) encoding the NPM-MLF1 fusion protein. In the other discrepant cases the aberrant cytoplasmic nucleophosmin staining and gene expression could not be explained. In total six patients (5%) had true discordant results between immunohistochemistry and molecular analysis. We conclude that cytoplasmic nucleophosmin localization is not always caused by a conventional nucleophosmin 1 mutation and that in the screening for nucleophosmin 1 abnormalities, most information will be obtained by combining immunohistochemistry with molecular analysis.
[Show abstract][Hide abstract] ABSTRACT: Acute Myeloid Leukemia (AML) bone marrow biopsies at diagnosis display enhanced angiogenesis and increased VEGFA expression. In a xenograft mouse model it was described that availability of free VEGFA versus bound VEGFA is related to different vascular morphology. In this study we investigate the relationship between vascular morphology within AML bone marrow biopsies and AML derived VEGFA levels.
Vessel count and surface area (Chalkley count) were calculated in AML bone marrow biopsies at diagnosis (n = 32), at remission (n = 8) and Normal Bone Marrow (n = 32) using immunohistochemical staining for FVIII, CD31, CTIV, SMA and VEGFA. VEGFA protein levels were measured.
High vessel count was associated with an immature vessel status. Combining vessel count and Chalkley count different vessel morphology patterns were quantified within AML bone marrow biopsies. Three different subgroups could be distinguished. The subgroup (37.5% of the samples) exhibiting a high vessel count and vessels with predominantly large lumen (normal Chalkley count) was associated with high secreted VEGFA protein levels.
Different vasculature patterns are seen in AML bone marrow biopsies, defined by combining number and size of vessel. These quantified morphology patterns, combined with VEGFA levels, might be of value in the success of VEGF/VEGFR-signaling interference approaches.
[Show abstract][Hide abstract] ABSTRACT: Patients with refractory anemia with ring sideroblasts and thrombocytosis (RARS-T) are difficult to treat because the cytoreductive treatment might be beneficial for the thrombocytosis component but harmful for the RARS component. As lenalidomide has shown to be efficacious in both myelodysplastic syndromes and myeloproliferative neoplasms, we have treated 2 RARS-T patients, who were transfusion dependent, with lenalidomide. We report the results of lenalidomide treatment in these patients and show that lenalidomide has clinical activity in this rare disorder. Both patients became transfusion independent, and 1 of the patients attained indeed a complete molecular remission.
[Show abstract][Hide abstract] ABSTRACT: Recent studies have shown that certain non-coding short RNAs, called miRNAs, play an important role in diffuse large B-cell lymphomas. Patients with diffuse large B-cell lymphoma have great diversity in both clinical characteristics, site of presentation and outcome. The aim of our study is to validate the differential expression in germinal center and non-germinal center diffuse large B-cell lymphoma,s and to study to the extent to which the primary site of differentiation is associated with the miRNA expression profile. We studied 50 cases of de novo diffuse large B-cell lymphoma for the expression of 15 miRNAs (miR-15a, miR-15b, miR-16, miR-17-3p, miR-17-5p, miR-18a, miR-19a, miR-19b, miR-20a, miR-21, miR-92, miR-127, miR-155, miR-181a and miR-221). Apart from 19 nodal cases without extranodal dissemination (stages I and II), we selected two groups with unambiguous stages I and II extranodal presentation; 9 cases of primary central nervous system, 11 cases of primary testicular and 11 cases of other primary extranodal diffuse large B-cell lymphomas. All cases were analyzed with qRT-PCR. In situ hybridization for the most differentially expressed miRNAs was performed to show miRNA expression in tumor cells, but not in background cells. MiR-21 and miR-19b showed the highest expression levels. No significant differences were seen between germinal center and non-germinal center diffuse large B-cell lymphomas in either the total or the nodal group for any of the 15 miRNAs. Two miRNAs showed significant differences in expression levels for diffuse large B-cell lymphoma subgroups according to the site of presentation. MiR-17-5p showed a significant higher expression level in the central nervous system compared with testicular and nodal diffuse large B-cell lymphomas (P<0.05). MiR-127 levels were significantly higher in testicular than in central nervous system and in nodal diffuse large B-cell lymphomas (P<0.05). We conclude that the location of diffuse large B-cell lymphoma is an important factor in determining the differential expression of miRNAs.
Modern Pathology 05/2009; 22(4):547-55. · 5.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mantle cell lymphoma (MCL) is characterized by genetic instability and a poor prognosis. Many blastoid variants are (hypo)tetraploid and have an even worse prognosis. We investigated the role of signalling by mitogen-activated protein kinases (MAPKs) in MCL. As compared to normal tonsil B cells, MCL cells showed higher activation of the JNK MAPK in both an MAPK array and a sandwich ELISA assay. Immunohistochemistry showed overexpression of phospho (p)-JNK (Thr183/Tyr185) in 30 of 37 MCL cases. Inhibition of p-JNK with SP600125 resulted in growth arrest in all four MCL cell lines (Jeko-1, HBL-2, UPN-1, Granta-519), which could be partly reversed by the addition of CD40L and IL-4. Furthermore, SP600125 led to G2/M phase arrest on day 1 and a striking increase in endoreduplication on day 2 and day 3, which was confirmed by karyotype analysis. G2/M arrest was associated with down-regulation of EGR1 and p21 protein expression. SP600125-induced polyploidy could be blocked by the BCL-2 inhibitor YC137. These data suggest that constitutive JNK activity is necessary to promote proliferation and maintain diploidy in MCL. JNK inhibition leads to cell cycle deregulation and endoreduplication, mimicking the tetraploid state seen in a subset of MCL cases. Thus, our data also provide an experimental model to study polyploid MCL cells.
The Journal of Pathology 02/2009; 218(1):95-103. · 7.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Chemotherapy with alemtuzumab and the combination of cyclophosphamide, adriamycin, oncovin, and prednisone (CHOP) has become experimental trial therapy for aggressive T-cell lymphoma. Several multicenter phase 3 trials will incorporate this scheme. As part of an ongoing phase 2 trial in which we recently treated 20 patients with 8 cycles of CHOP every 2 weeks with 3 additional doses of 30 mg alemtuzumab per cycle, we observed the development of Epstein-Barr virus (EBV)-positive lymphoproliferative disease, after completion of the immunochemotherapy in 3 patients with peripheral T-cell lymphoma. Because the occurrence of EBV-positive lymphoproliferative disease is rare after alemtuzumab monotherapy, such as is given for chronic lymphocytic leukemia, we think that early reporting of this potential side effect is warranted. It may be caused by intrinsic T-cell defects in patients with T-cell lymphoma, or by the combination of alemtuzumab with CHOP chemotherapy.
[Show abstract][Hide abstract] ABSTRACT: Several miRNAs have been reported to be associated with immunoglobulin heavy chain (IgH) mutation and ZAP-70 expression status in blood samples of B-cell chronic lymphocytic leukaemia/small lymphocytic lymphoma (B-CLL/SLL). In the bone marrow and lymphoid tissues, proliferation centres (PCs) represent an important site of activation and proliferation of the neoplastic cells, suggesting that these tissues better reflect the biology of CLL than circulating blood cells. We collected 33 lymph nodes and 37 blood CLL samples and analysed IgH mutation status and ZAP-70 expression status. Expression of 15 miRNAs was analysed by qRT-PCR and RNA-ISH. Sixty-three per cent of the lymph node cases contained mutated IgH genes and 49% of the lymph node cases were ZAP-70-positive, and a significant correlation was observed between ZAP-70 expression and IgH mutation status. Of the blood CLL samples, 49% contained mutated IgH sequences. The miRNA expression pattern in CLL lymph node and blood samples was very similar. Three of 15 miRNAs (miR-16, miR-21, and miR-150) showed a high expression level in both blood and lymph node samples. No difference was observed between ZAP-70-positive or -negative and between IgH-mutated or unmutated cases. No correlation was found between miR-15a and miR-16 expression levels and 13q14 deletion in the blood CLL samples. RNA in situ hybridization (ISH) revealed strong homogeneous staining of miR-150 in the tumour cells outside the PCs. In reverse BIC/pri-miR-155 expression was observed mainly in individual cells including prolymphocytes of the PCs. This reciprocal pattern likely reflects the different functions and targets of miR-150 and miR-155.
The Journal of Pathology 06/2008; 215(1):13-20. · 7.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A prompt distinction of Burkitt lymphoma (BL) versus diffuse large B cell lymphomas (DLBCL) has important clinical implications; however, this distinction can be difficult. We analyzed 74 adult gray zone and 10 reference pediatric BL using immunohistochemistry (Ki-67, CD10, bcl2, bcl6) and fluorescence in situ hybridization (FISH) for MYC, BCL2, and BCL6 breakpoints. Two algorithms for classification were followed: algorithm A used a two-step review by four hemato-pathologists and algorithm B a set of only biologic markers (Ki-67 > or = 90%, CD10+, bcl6+, bcl2-, MYC breakpoint+, BCL2 and BCL6 breakpoint-). Both algorithms categorized all reference cases as BL. In the adult group, algorithm A resulted in 21 adult BL and 52 DLBCL and algorithm B in 23 BL and 51 "non-Burkitt" lymphomas (nBL); 9 cases (12%) contained two different translocations and were categorized as nBL in algorithm B. Fifteen cases (20%) fulfilled the BL criteria of both algorithms. Although not considered as BL according to both algorithms, many other lymphomas showed nonetheless a phenotypic and/or genetic shift to BL. BL according to algorithm B was more homogeneous with respect to clinical presentation (gender and localization) than BL defined by algorithm A. Our data suggest that only a few cases of these gray zone lymphomas represent true de novo BL. Immunohistochemistry for Ki-67, CD10, and bcl2 with analysis of MYC and preferably also BCL2 and BCL6 may be advised as a marker panel for this diagnostic dilemma.
American Journal of Surgical Pathology 09/2005; 29(8):1086-94. · 4.87 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Immunophenotyping of B cell chronic lymphocytic leukaemia (B-CLL) is usually performed by flow cytometry on cell suspensions obtained from peripheral blood, bone marrow or biopsied tissue. Immunohistochemical analysis on routine sections is less commonly performed; however, this approach allows the pathologist and the researcher to appreciate the immuno-architecture of the involved tissues and to gain insight into some of the events that influence the biology of the disease. In this review the authors focus on the following issues: immuno-architecture of the proliferation centres, expression of CD23, MUM1/IRF-4 and cyclin D1, tyrosine phosphorylation and detection of the ZAP-70 kinase. Whenever possible, an attempt is made to interpret the immunohistochemical findings from a functional point of view.
Current topics in microbiology and immunology 02/2005; 294:91-107. · 4.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the present study the immunohistochemical expression of Bcl-xl, a downstream target of the IL-6-controlled signal transducer and activator of transcription-3 (Stat3) was studied in 40 multiple myeloma (MM) cases before treatment and 11 MM patients at relapse. Correlation analysis was performed between Bcl-xl expression, C-reactive protein (CRP) level, beta-2-microglobulin (beta2m), microvessel density (MVD), and clinical outcome. Before treatment 28 (70%) patients demonstrated a Bcl-xl expression similar to normal plasma cells ("normal pattern"), while 12 (30%) patients demonstrated an elevated expression in a subgroup of the malignant plasma cells. At relapse, no change in Bcl-xl expression was observed as compared to pretreatment sample. No correlation was observed between the Bcl-xl expression and the level of CRP and b2m. In addition, no significant correlation was observed between the Bcl-xl expression and the MVD, but MVD was significantly increased as compared to normal bone marrow biopsy specimens (p=0.02). Patients with an elevated or normal Bcl-xl expression showed no statistically significant difference in overall and event-free survival. In summary, these data indicate that Bcl-xl is elevated in a subgroup of MM patients that so far did not correlate with CRP, b2m, MVD, and clinical outcome.
Medical Oncology 02/2005; 22(2):183-90. · 2.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A chromosomal translocation involving the MYC gene is characteristic of Burkitt lymphoma (BL) and represents a molecular disease marker with diagnostic and clinical implications. The detection of MYC breakpoints is hampered by technical problems, including the distribution of the breakpoints over a very large genomic region of approximately 1,000 kb. In this article, we report on the testing and validation of a segregation fluorescence in situ hybridization (FISH) assay for MYC breakpoints on a large series of BLs. A contig of overlapping genomic clones was generated, and two probe sets flanking the MYC gene were selected. Both probe sets were tested in an interphase FISH segregation assay on 8 B-cell lymphoma cell lines and 32 lymphoma samples with proved 8q24/MYC abnormalities and validated in 47 BLs from The Netherlands, Brazil, and Uganda. MYC translocation breakpoints were identified in 98% of the tumors of the test series and in 89% of the cases of the validation series. In 89% of all positive samples, the breakpoints were located between 190 kb 5' and 50 kb 3' of MYC. Nine cases had more distant breakpoints, and in one patient an insertion of MYC into the IGH region was detected. In two of the three BLs lacking CD10 expression, no breakpoint could be detected, suggesting that CD10 is a discriminative marker of BL. We did not find consistent differences between BL and atypical BL in incidence of an MYC breakpoint.
Genes Chromosomes and Cancer 06/2004; 40(1):10-8. · 3.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Epithelioid cell granulomas have been reported in association with a wide range of neoplasms including malignant lymphomas. In lymphoma, this refers mainly to Hodgkin disease and T-cell-derived non-Hodgkin lymphomas where a granulomatous reaction is probably evoked by aberrant cytokine production in the tumor cells or other cells composing the tumor background. Here we report on four cases of sporadic Burkitt lymphoma with unusual florid granulomatous reaction. In all samples, the tumor cells were admixed with numerous epithelioid cells that formed clusters and granulomatous lesions. No microorganisms could be detected at the tissue level, and there were no clinical or laboratory indications of an underlying immunodeficiency. The lymphomas harbored a specific morphology and immunophenotype of Burkitt lymphoma, and the presence of translocation breakpoint in MYC gene was confirmed by interphase fluorescence in situ hybridization. In all four patients, the lymphoma was associated with Epstein-Barr virus infection, detected by EBER in situ hybridization and the latency I phenotype as defined by lack of expression of LMP1. All four patients were treated with polychemotherapy, achieved a complete remission, and are alive without evidence of disease. We draw attention to this unusual phenomenon as it caused difficulties in interpretation and delayed diagnosis and hypothesize on the possible role of Epstein-Barr virus products.
American Journal of Surgical Pathology 04/2004; 28(3):379-83. · 4.87 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although many patients with acute leukemia achieve a hematological complete remission with aggressive intensive therapy protocols, a large proportion shows reoccurrence of disease. Novel strategies are warranted. In acute leukemia new vessel formation is observed. New vessel formation is the result of angiogenesis and vasculogenesis. The degree of neovascularization in the bone marrow is correlated with vascular endothelial growth factor (VEGF) expression in the leukemic cells. The present review discusses the impact of new vessel formation related to acute leukemia, the relation with various angiogenic factors and will focus on VEGF/VEGF receptor signaling.
Leukemia and Lymphoma 11/2002; 43(10):1901-9. · 2.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present study demonstrated that the vessel number in bone marrow biopsies from acute myeloid leukaemia (AML) patients (n = 23) was significantly increased at diagnosis compared with normal bone marrow (P = 0.019) and was restored to normal levels after achieving complete remission (P = 0.03). The in vitro angiogenic potential of culture supernatant of AML cells was assessed using endothelial cell (EC) migration and proliferation assays. Increased EC migration and EC proliferation was induced in 7/20 and 19/20 AML supernatents respectively. The degree of in vivo neovascularization did not correlate with the ability of AML cells to stimulate in vitro endothelial cell migration and/or proliferation. This might be in part a result of the heterogeneous pattern of angiogenic factors produced by AML cells. The expression of different angiogenic factors was studied using reverse transcription polymerase chain reaction. Cells from 17/20 AML patients showed wide variation in spontaneous vascular endothelial growth factor (VEGF) expression, 4/19 expressed varied spontaneous blastic fibroblast growth factor mRNA levels and all patient samples showed spontaneous interleukin 8 mRNA expression. All AML samples expressed matrix metalloproteinase (MMP)-2 and/or MMP-9. VEGF mRNA expression correlated well with protein level (P = 0.006). A correlation was found between the degree of VEGF expression and neoangiogenesis (correlation coefficient = 0.448, P = 0.05). These results suggest that malignant cell proliferation, angiogenesis and VEGF expression are linked in AML and might contribute to the growth advantage of the malignant counterpart as a result of the paracrine production of growth factors produced by the surrounding endothelial cells.
British Journal of Haematology 06/2001; 113(2):296-304. · 4.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present study demonstrated that the vessel number in bone marrow biopsies from acute myeloid leukaemia (AML) patients (n = 23) was significantly increased at diagnosis compared with normal bone marrow (P = 0·019) and was restored to normal levels after achieving complete remission (P = 0·03). The in vitro angiogenic potential of culture supernatant of AML cells was assessed using endothelial cell (EC) migration and proliferation assays. Increased EC migration and EC proliferation was induced in 7/20 and 19/20 AML supernatents respectively. The degree of in vivo neovascularization did not correlate with the ability of AML cells to stimulate in vitro endothelial cell migration and/or proliferation. This might be in part a result of the heterogeneous pattern of angiogenic factors produced by AML cells. The expression of different angiogenic factors was studied using reverse transcription polymerase chain reaction. Cells from 17/20 AML patients showed wide variation in spontaneous vascular endothelial growth factor (VEGF) expression, 4/19 expressed varied spontaneous blastic fibroblast growth factor mRNA levels and all patient samples showed spontaneous interleukin 8 mRNA expression. All AML samples expressed matrix metalloproteinase (MMP)-2 and/or MMP-9. VEGF mRNA expression correlated well with protein level (P = 0·006). A correlation was found between the degree of VEGF expression and neoangiogenesis (correlation coefficient = 0·448, P = 0·05). These results suggest that malignant cell proliferation, angiogenesis and VEGF expression are linked in AML and might contribute to the growth advantage of the malignant counterpart as a result of the paracrine production of growth factors produced by the surrounding endothelial cells.
British Journal of Haematology 04/2001; 113(2):296 - 304. · 4.94 Impact Factor