c-Rel Is the Pivotal NF-κB Subunit in Germinal Center Diffuse Large B-Cell Lymphoma: A LYSA Study.

Relationships between c-Rel and GCB-DLBCLs remain unclear. We found that strong c-Rel DNA-binding activity was mostly found in GCBs on two independent series of 48 DLBCLs and 66 DLBCLs, the latter issued from the GHEDI series. c-Rel DNA-binding activity was associated with increased REL mRNA expression. Extending the study to the whole GHEDI and Lenz DLBCL published series of 202 and 233 cases, it was found that the c-Rel gene expression profile (GEP) overlapped partially (12%) but only with the GCB GEP and not with the GEP of ABC-DLBCLs. Cases with both overexpression of REL mRNA and c-Rel GEP were defined as those having a c-Rel signature. These cases were GCBs in 88 and 83% of the GHEDI or Lenz's DLBCL series respectively. The c-Rel signature was also associated with various recurrent GCB-DLBCL genetic events, including REL gains, BCL2 translocation, MEF2B, EZH2, CREBBP, and TNFRSF14 mutations and with the EZB GCB genetic subtype. By CGH array, the c-Rel signature was specifically correlated with 2p15-16.1 amplification that includes XPO1, BCL11A, and USP34 and with the 22q11.22 deletion that covers IGLL5 and PRAME. The total number of gene copy number aberrations, so-called genomic imbalance complexity, was decreased in cases with the c-Rel signature. These cases exhibited a better overall survival. Functionally, overexpression of c-Rel induced its constitutive nuclear localization and protected cells against apoptosis while its repression tended to increase cell death. These results show that, clinically and biologically, c-Rel is the pivotal NF-κB subunit in the GCB-DLBCL subgroup. Functionally, c-Rel overexpression could directly promote DLBCL tumorigenesis without need for further activation signals.

Prohibitin (PHB) expression is associated with aggressiveness in DLBCL and flavagline-mediated inhibition of cytoplasmic PHB functions induces anti-tumor effects.

BACKGROUND: Diffuse large B-cell lymphomas (DLBCLs) are aggressive lymphomas accounting for approximately a third of non-Hodgkin lymphomas. Prohibitin 1 (PHB1) and prohibitin 2 (PHB2) are scaffold proteins that promote mitochondria homeostasis and consequently cell survival, but biological functions of cytoplasmic PHBs remain largely unknown in DLBCL. METHODS: PHB expression was analyzed in 82 DLBCL biopsies and five DLBCL cell lines by immunohistochemistry (IHC) and Western blotting. Pharmacological inhibition of PHB using the synthetic flavagline FL3 was realized in vitro to gain insight PHB cellular functions. Effects of FL3 on DLBCL cell line viability, apoptosis, C-Raf-ERK-MNK-eIF4E signaling pathway and eIF4F complex formation and activity were evaluated by XTT assay, annexin V-FITC/PI dual staining and Western blotting respectively. Subcutaneous DLBCL xenograft model in SCID mice was also performed to determine in vivo FL3 effect. RESULTS: As in DLBCL cell lines, PHB1 and PHB2 were expressed in germinal center B-cell-like (GCB) and activated B-cell-like (ABC) subtypes. In patient samples, high PHB levels were associated with higher serum LDH (PHB1 and PHB2), IPIaa (PHB2), and Ki-67 (PHB2) expression. Higher PHB1 expression tends to be associated with shorter event-free survival (EFS) in patients, especially in male patients. FL3 induced apoptosis of DLBCL cell lines that was associated with inhibition of the ERK-MNK-eIF4E signaling pathway, including aggressive double/triple-hit DLBCL cell lines. This resulted in altered eIF4F complex formation and activity leading to a reduction of Bcl-2 and c-Myc expression levels. Moreover, FL3 strongly downregulated DLBCL cellular levels of Akt protein and AKT mRNA. FL3 antitumor activity was also confirmed in vivo in a murine xenograft model. CONCLUSION: Our data indicate that PHB overexpression is associated with markers of tumor aggressiveness in DLBCL, and that targeting PHBs may be a therapeutic option, notably in aggressive subtypes.

Anti-apoptotic role and clinical relevance of neurotrophins in diffuse large B-cell lymphomas.

BACKGROUND: Diffuse large B-cell lymphoma (DLBCL) is a fatal malignancy that needs to identify new targets for additional therapeutic options. This study aimed to clarify the clinical and biological significance of endogenous neurotrophin (nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF)) in DLBCL biopsy samples and cell lines. METHODS: We analysed expression of NGF, BDNF, and their receptors (Trk, p75(NTR)) in 51 biopsies and cell lines by immunohistochemistry, immunofluorescence, and western blotting. To investigate the biological role of BDNF/TrkB/p75(NTR) axis, effects of neurotrophin signalling inhibition were determined on tumour cell survival and vascular endothelial growth factor (VEGF) secretion. The pharmacological pan-Trk inhibitor K252a was used for in vitro and in vivo studies. RESULTS: A BDNF/TrkB axis was expressed in all biopsies, which was independent of the germinal centre B-cell (GCB)/non-GCB profile. p75(NTR), TrkB, and BDNF tumour scores were significantly correlated and high NGF expression was significantly associated with MUM1/IRF4, and the non-GCB subtype. Diffuse large B-cell lymphoma cell lines co-expressed neurotrophins and their receptors. The full-length TrkB receptor was found in all cell lines, which was also phosphorylated at Tyr-817. p75(NTR) was associated to Trk and not to its cell death co-receptor sortilin. In vitro, inhibition of neurotrophin signalling induced cell apoptosis. K252a caused cell apoptosis, decreased VEGF secretion, and potentiated rituximab effect, notably in less rituximab-sensitive cells. In vivo, K252a significantly reduced tumour growth and potentiated the effects of rituximab in a GCB-DLBCL xenograft model. CONCLUSIONS: This work argues for a pro-survival role of endogenous neurotrophins in DLBCLs and inhibition of Trk signalling might be a potential treatment strategy for rituximab resistant subgroups.

Efficacy of L-asparaginase with methotrexate and dexamethasone (AspaMetDex regimen) in patients with refractory or relapsing extranodal NK/T-cell lymphoma, a phase 2 study.

Extranodal NK/T-cell lymphoma, nasal type, is a rare and highly aggressive disease with a grim prognosis. No therapeutic strategy is currently identified in relapsing patients. We report the results of a French prospective phase II trial of an L-asparaginase-containing regimen in 19 patients with relapsed or refractory disease treated in 13 centers. Eleven patients were in relapse and 8 patients were refractory to their first line of treatment. L-Asparaginase-based treatment yielded objective responses in 14 of the 18 evaluable patients after 3 cycles. Eleven patients entered complete remission (61%), and only 4 of them relapsed. The median overall survival time was 1 year, with a median response duration of 12 months. The main adverse events were hepatitis, cytopenia, and allergy. The absence of antiasparaginase antibodies and the disappearance of Epstein-Barr virus serum DNA were significantly associated with a better outcome. These data confirm the excellent activity of L-asparaginase-containing regimens in extranodal NK/T-cell lymphoma. L-Asparaginase-based treatment should thus be considered for salvage therapy, especially in patients with disseminated disease. First-line L-asparaginase combination therapy for extranodal NK/T-cell lymphoma warrants evaluation in prospective trials. This trial is registered at www.clinicaltrials.gov as #NCT00283985.

Involvement of human herpesvirus-6 variant B in classic Hodgkin's lymphoma via DR7 oncoprotein.

PURPOSE: Hodgkin's lymphoma (HL) is associated with the presence of EBV in Reed-Sternberg (RS) cells in ∼40% of cases. Here, we studied the presence of human herpesvirus type 6 (HHV-6) variant B in RS cells of HL patients and correlated results with clinical parameters. We then examined the implication of HHV-6 DR7B protein in cell deregulation. EXPERIMENTAL DESIGN: HHV-6 DR7B protein was produced in a Semliki Forest virus system. Polyclonal antibodies were then generated and used for immunochemical HHV-6 localization in HL biopsies. Binding between DR7B and p53 was studied using a double-hybrid system. Transactivation of NFκB was observed after transient transfection using reporter gene assays. We looked for Id2 factor expression after stable transfection of the BJAB cell line by reverse transcription-PCR and Western blot analysis. RESULTS: HHV-6 was more common in nodular sclerosis subtype HL, and DR7B oncoprotein was detected in RS cells for 73.7% of EBV-negative patients. Colocalization of EBV and HHV-6 was observed in RS cells of doubly infected patients. DR7B protein bound to human p53 protein. p105-p50/p65 mRNA expression and activation of the NFκB complex were increased when DR7B was expressed. Stable expression of DR7B exhibited a strong and uniform expression of Id2. A slightly higher percentage of remission was observed in patients with RS cells testing positive for DR7B than in those testing negative. CONCLUSIONS: Collectively, these data provide evidence for the implication of a novel agent, HHV-6, in cases of nodular sclerosis HL.

Prognostic significance of BAD and AIF apoptotic pathways in diffuse large B-cell lymphoma.

BACKGROUND: To determine whether proapoptotic proteins were associated with clinicopathologic heterogeneity and influenced survival in patients with diffuse large B-cell lymphoma (DLBCL), we evaluated patterns of expression of the BCL-2 family member BAD, PP1alpha (the catalytic subunit of PP1 involved in activation of BAD), and apoptosis-inducing factor (AIF). PATIENTS AND METHODS: We retrospectively analyzed 46 patients all treated with standard chemotherapy ([CHOP] cyclophosphamide/doxorubicin/vincristine/prednisone-like); of these, 16 received rituximab. Immunohistochemical analyses were performed from biopsy samples of nodal DLBCL that were performed at initial diagnosis. Normal reactive lymph nodes were used as controls. RESULTS: BAD expression was found in 38 of 46 DLBCL cases and, though variable, was often strong. PP1alpha and AIF were detected in all tumors tested with a relative strong expression. Lower BAD expression was shown to be significantly associated with advanced clinical stages (Ann Arbor stage III + IV and International Prognostic Index intermediate-high to high; P = .006 and P = .0008, respectively). Moreover, BAD staining was positively correlated with BCL-2 (P = .022) and PP1alpha (P = .013) staining. Finally, high AIF expression proved to be predictive of a longer overall survival in non-rituximab-treated patients. CONCLUSION: Our study shows for the first time in DLBCL that differential BAD expression might play a role in the development of the disease, possibly reflecting its function as a tumor suppressor. Furthermore, our data highlight the interest in targeting BAD phosphatases and AIF-mediated mitochondrial apoptosis for new therapeutic strategies.

Gene expression profiling identifies emerging oncogenic pathways operating in extranodal NK/T-cell lymphoma, nasal type.

Biopsies and cell lines of natural killer/T-cell lymphoma, nasal type (NKTCL) were subject to combined gene expression profiling and array-based comparative genomic hybridization analyses. Compared with peripheral T-cell lymphoma, not otherwise specified, NKTCL had greater transcript levels for NK-cell and cytotoxic molecules, especially granzyme H. Compared with normal NKcells, tumors were closer to activated than resting cells and overexpressed several genes related to vascular biology, Epstein-Barr Virus-induced genes, and PDGFRA. Notably, platelet-derived growth factor receptor alpha and its phosphorylated form were confirmed at the protein level, and in vitro the MEC04 NKTCL cell line was sensitive to imatinib. Deregulation of the AKT, Janus kinase-signal transducers and activators of transcription, and nuclear factor-kappaB pathways was corroborated by nuclear expression of phosphorylated AKT, signal transducers and activators of transcription 3, and RelA in NKTCL, and several deregulated genes in these pathways mapped to regions of recurrent copy number aberrations (AKT3 [1q44], IL6R [1q21.3], CCL2 [17q12], TNFRSF21 [6p12.3]). Several features of NKTCL uncovered by this analysis suggest perturbation of angiogenic pathways. Integrative analysis also evidenced deregulation of the tumor suppressor HACE1 in the frequently deleted 6q21 region. This study highlights emerging oncogenic pathways in NKTCL and identifies novel diagnostic and therapeutic targets.

Peripheral T-cell lymphomas with a follicular growth pattern are derived from follicular helper T cells (TFH) and may show overlapping features with angioimmunoblastic T-cell lymphomas.

Rare cases of peripheral T-cell lymphomas with follicular growth pattern (PTCL-F) have been recently reported, and their association with t(5;9)(q33;q22) involving ITK and SYK has been suggested. However, the clinicopathologic aspects of PTCL-F are poorly described and the normal cell counterpart of this subgroup of lymphoma is still unknown. Therefore, we analyzed the pathologic, phenotypic, and cytogenetic features of a series of 30 patients (range: 33 to 88 y) that showed histopathologic features of PTCL-F in at least 1 biopsy (n=30), either at initial presentation (n=26) or at relapse (n=4). Neoplastic cells were medium-sized clear cells that were CD4+ (24/27, 89%), CD10+ (21/29, 72%), BCL-6+ (14/19, 74%), and expressed programed death-1 (27/27, 100%), CXCL13 (23/27, 85%), and ICOS (11/11, 100%), markers of follicular helper T cells (TFH). Four of 22 patients (18%) had t(5;9)(q33;q22) detected by fluorescence in situ hybridization. Patients with clinical data available had multiple lymphadenopathies (25/28, 89%), stage III to IV diseases (17/26, 65%), B symptoms (7/27, 26%), and skin lesions (6/23, 26%). Three patients with sequential biopsies disclosed clinical and histopathologic features of angioimmunoblastic T-cell lymphoma at initial presentation. Our results show that this rare form of PTCL-F (1) has an immunophenotype indicative of derivation from TFH cells, (2) is associated with t(5;9) in a proportion of cases, and (3) shows some overlapping features with angioimmunoblastic T-cell lymphoma, raising the question of a possible relationship.

Uncoupling between Ig somatic hypermutation and oncogene mutation in mouse lymphoma.

Burkitt lymphoma (BL) features translocations linking c-myc to the immunoglobulin heavy chain (IgH) locus. By inserting a c-myc gene under the control of the 3'IgH locus control region (LCR) into the mouse genome, we generated c-myc-3'LCR mice that develop clonal BL or diffuse anaplastic lymphoma. We show in the present study that while BL from c-myc-3'LCR mice would be classified as pre-germinal center (GC) cells due to the absence of both BCL-6 expression and somatic hypermutation (SHM) in V(H) sequences, they show a high level of SHM focused on the c-myc oncogene itself. This observation suggests that the c-myc-3'IgH LCR tandem association drives development of lymphoma from naïve B cells by specifically recruiting AID activity on c-myc in a process that early becomes independent from antigen selection and where the successive rounds of SHM rather rely on the selection of the most efficient mutations for oncogene deregulation. Similar to the translocated c-myc gene in human BL, mutations were found in first exon and 5' flanking sequences of transgenic c-myc and specially focused on negative regulatory elements, thus leading to high and constitutive oncogene expression. In conclusion while 3'IgH transcriptional enhancers in c-myc-3'LCR mice first simply act in cis to slightly stimulate c-myc transcription in untransformed B cells, the occurrence of lymphoma appears to result from an additional mechanism necessitating AID-driven mutations within the first exon and 5' flanking sequences which does not occur in parallel but rather circumvents antigen-driven selection.

Extraocular muscle involvement in marginal zone B-cell lymphomas of the orbit.

INTRODUCTION: Marginal zone B-cell lymphoma is the most frequent ocular adnexal lymphoma. It may involve the conjunctiva, lacrimal gland, eyelid, extraocular muscle, and orbital connective tissue. Extraocular muscle infiltration is rare. METHODS: We report here a series of 5 patients presenting with extraocular muscle infiltration due to marginal zone B-cell lymphoma, extracted from a retrospective study of 39 patients with primitive ocular adnexal marginal zone B-cell lymphoma presenting within a 15-year period, from 1993 to 2007, at two university hospitals. RESULTS: Out of 39 patients, two females and three males presented with extraocular muscle involvement (one levator muscle, one medial rectus muscle, one lateral rectus muscle, one inferior rectus muscle, and one inferior oblique muscle). In 4 cases, the right eye was involved. The median age of presentation was 60 years. Proptosis and diplopia were the main clinical signs. A mean duration of symptoms was 12 months before diagnosis was given. Three patients were stage IE at the diagnosis, according to Ann Arbor classification, and one was at stage IV. Three patients received radiotherapy and two received chemotherapy. Three patients underwent local relapses at a median time of 40 months. The patients with relapses were treated with chemotherapy alone in one case, radiotherapy alone in one case, and immunotherapy and chemotherapy in one case. The mean follow-up period was 54 months. DISCUSSION: When compared to other locations of marginal zone B-cell lymphomas of the orbit, extraocular involvement occurred in younger patients and had similar prognosis. CONCLUSION: Extraocular muscle involvement is a rare location of marginal zone B-cell lymphoma that had to be known and can simulate thyroid orbitopathy.

T cell receptor genotyping and HOXA/TLX1 expression define three T lymphoblastic lymphoma subsets which might affect clinical outcome.

PURPOSE: T lymphoblastic lymphomas (T-LBL) are rare disorders of immature T cells which predominantly involve the mediastinum. Their oncogenic pathways and prognostic variables are not clear. EXPERIMENTAL DESIGN: We undertook a retrospective study of 41 cytoplasmic CD3+ T-LBL (nine cases aged <16 years) by assessing stage of maturation arrest based on T cell receptor (TCR) immunogenotyping, immunohistochemistry, and quantification of the oncogenes thought to be important in immature T cell malignancies. RESULTS: Application of a TCR-based immunogenetic classification allowed the identification of three subcategories: 11 immature IM0/D-LBL showed no TCR or only incomplete TCRD DJ rearrangement and corresponded to cytoplasmic CD3+ precursors of uncertain lineage. Sixteen mature TCRD(del)-LBL showed biallelic TCRD deletion and both TCRG and TCRB rearrangement, consistent with TCRalphabeta lineage restriction. Fourteen intermediate LBL (Int-LBL) showed complete TCRD VDJ and TCRG VJ rearrangement, with TCRB VDJ rearrangement in the majority. All Int-LBL expressed HOX11/TLX1 or HOXA9 transcripts and a proportion of the latter were associated with CALM-AF10 or NUP214-ABL fusion transcripts. IM0/D-LBL were restricted to adults with extrathymic disease and bone marrow involvement, whereas Int-LBL and TCRD(del)-LBL were found in children and adults with predominantly thymic disease. In adults, the Int-LBL subgroup was associated with a significantly superior clinical outcome. This subgroup can be identified either by TCR immunogenotyping or HOXA9/TLX1 transcript quantification. CONCLUSION: Application of this molecular classification will allow the prospective evaluation of prognostic effects within pediatric and adult protocols.

The 3' IgH locus control region is sufficient to deregulate a c-myc transgene and promote mature B cell malignancies with a predominant Burkitt-like phenotype.

Burkitt lymphoma (BL) features translocations linking c-myc to an Ig locus. Breakpoints in the H chain locus (IgH) stand either close to J(H) or within switch regions and always link c-myc to the 3' IgH locus control region (3' LCR). To test the hypothesis that the 3' LCR alone was sufficient to deregulate c-myc, we generated mice carrying a 3' LCR-driven c-myc transgene and specifically up-regulating c-myc in B cells. Splenic B cells from mice proliferated exaggeratedly in response to various signals had an elevated apoptosis rate but normal B220/IgM/IgD expression. Although all Ig levels were lowered in vivo, class switching and Ig secretion proved normal in vitro. Beginning at the age of 12 wk, transgenic mice developed clonal lymphoblastic lymphomas or diffuse anaplastic plasmacytomas with an overall incidence of 80% by 40 wk. Lymphoblastic lymphomas were B220(+)IgM(+)IgD(+) with the BL "starry sky" appearance. Gene expression profiles revealed broad alterations in the proliferation program and the Ras-p21 pathway. Our study demonstrates that 3' IgH enhancers alone can deregulate c-myc and initiate the development of BL-like lymphomas. The rapid and constant occurrence of lymphoma in this model makes it valuable for the understanding and the potential therapeutic manipulation of c-myc oncogenicity in vivo.

HHV-6 and EBV DNA quantitation in lymph nodes of 86 patients with Hodgkin's lymphoma.

Human herpesvirus (HHV-6) and Epstein-Barr virus (EBV), are two ubiquitous human herpesviruses which share many common features although they belong to different sub-families. In particular, both viruses are found in lymph nodes of patients suffering from Hodgkin's lymphoma. The aim of this study was to detect and to quantify independently HHV-6 and EBV by a real-time PCR in lymph nodes from 86 patients with Hodgkin's lymphoma. EBV quantitative method was compared with LMP-1 protein detection among the same samples. EBV genome was detected for 61.6% of the patients (53/86) and the highest prevalence of this virus was observed in Hodgkin's lymphoma with mixed-cellularity histopathological type (80%). In contrast to that, HHV-6 genome was detected for 79.1% of the patients (68/86) and was most observed in the nodular-sclerosis group (83.6%). Among the 68 HHV-6 positive samples, 63 belonged to the B subtype. A large number of biopsies (47.7%) were positive for both viruses whereas a little number (7%) was negative for both. EBV quantitation and LMP-1 immunohistochemistry were correlated statistically but this latter technique was less sensitive. Among the nodular-sclerosis patients, HHV-6-/EBV+ patients were significatively older than HHV-6+/EBV- patients. Patients infected dually had higher values of quantitation for each virus than those positive for one virus. Data of the clinical follow-up obtained by diagnosis and during the treatment of 83 patients, were correlated with the virological findings.

Novel GALNT3 mutations causing hyperostosis-hyperphosphatemia syndrome result in low intact fibroblast growth factor 23 concentrations.

CONTEXT: Hyperostosis-hyperphosphatemia syndrome (HHS) is a rare metabolic disorder characterized by hyperphosphatemia and localized hyperostosis. HHS is caused by mutations in GALNT3, which encodes UDP-N-acetyl-alpha-D-galactosamine:polypeptide N- acetylgalactosaminyltransferase 3. Familial tumoral calcinosis (TC), characterized by ectopic calcifications and hyperphosphatemia, is caused by mutations in the GALNT3 or fibroblast growth factor 23 (FGF23) genes. OBJECTIVE: Our objective was to identify mutations in FGF23 or GALNT3 and determine serum FGF23 levels in an HHS patient. DESIGN: Mutation detection in FGF23 and GALNT3 was performed by DNA sequencing, and serum FGF23 concentrations were measured by ELISA. PATIENTS OR OTHER PARTICIPANTS: A 5-year-old French boy with HHS and his family members participated. RESULTS: The patient presented with painful cortical lesions in his leg. Radiographs of the affected bone showed diaphyseal hyperostosis. The lesional tissue comprised trabeculae of immature, woven bone surrounded by fibrous tissue. Biochemistry revealed elevated phosphate, tubular maximum rate for phosphate reabsorption per deciliter of glomerular filtrate, and 1,25-dihydroxyvitamin D levels. The patient was a compound heterozygote for two novel GALNT3 mutations. His parents and brother were heterozygous for one of the mutations and had no biochemical abnormalities. Intact FGF23 level in the patient was low normal, whereas C-terminal FGF23 was elevated, a pattern similar to TC. CONCLUSION: The presence of GALNT3 mutations and elevated C-terminal, but low intact serum FGF23, levels in HHS resemble those seen in TC, suggesting that HHS and TC are different manifestations of the same disorder. The absence of biochemical abnormalities in the heterozygous individuals suggests that one normal allele is sufficient for secretion of intact FGF23.

Indolent lymphoplasmacytic and marginal zone B-cell lymphomas: absence of both IRF4 and Ki67 expression identifies a better prognosis subgroup.

BACKGROUND AND OBJECTIVES: Small B-cell indolent lymphomas postulated to be of a post-germinal center origin include marginal zone lymphomas of the spleen (S-MZL) or lymph nodes (N-MZL) and mucosa-associated lymphoid tissue (MALT) lymphomas and lymphoplasmacytic lymphomas (LPL). The existence of rather aggressive cases stresses the need for new biological prognostic markers. DESIGN AND METHODS: We analyzed 90 tumors (20 LPL, 41 MALT lymphomas, 12 N-MZL, 17 S-MZL), investigating the expression of CD5, CD10, CD20, CD23, CD27, CD38, CD79a, CD138, Bcl6, cyclin D1, IRF4 and Ki67 antigens by immunohistochemistry. Results were compared to the histology, the standard clinical and biological parameters, and the global survival. RESULTS: Tumors were all positive for CD20 and CD79a, occasionally positive for CD5, CD23, CD138 and cyclin D1, and all negative for Bcl-6 and CD10. CD38, CD27 and IRF4 expression was heterogeneous. IRF4 expression was correlated with plasma-cell differentiation (p=0.0017). Ki67 expression was increased mainly in N-MZL (66%) and LPL (45%). In terms of overall survival, Ki67, IRF4 and C-reactive protein levels were found to be the 3 independent parameters associated with a worse outcome. Lack of both Ki67 and IRF4 expression was associated with a longer survival (median overall survival 9.8+/-1.1 years versus 3.6+/-1.3 years in the other group) (p=0.0011). INTERPRETATIONS AND CONCLUSIONS: Absence of expression of both Ki67 and IRF4 is likely to define a group of memory B-cell lymphomas with a better prognosis. This may have an important impact in the staging of patients since expression of these markers is easily assessed in routine diagnosis.

Brefeldin A induces apoptosis and cell cycle blockade in glioblastoma cell lines.

Brefeldin A (BFA), a fungal metabolite known to affect the structure and function of the Golgi apparatus, has recently been shown to induce apoptosis and cell growth inhibition in various human cell lines. Glioblastomas (GB) are cerebral tumors with poor prognosis, which display resistance to current therapies including radio- and chemotherapy. The objective of this study was to investigate BFA effects in three human GB cell lines (SA4, SA146 and U87MG cells). Compared with control cells, about 60% of cell growth inhibition was observed in BFA (100 ng/ml for 24 h)-exposed cells in the three cell lines. Furthermore, in SA4 and SA146 cells, BFA was able to induce a time- and dose-dependent apoptosis detected by DAPI staining, TUNEL assay and flow-cytometric analysis. Since p53 expression was not modified after BFA exposure, BFA-induced apoptosis may follow a p53-independent pathway, as already reported. In the same way, BFA did not alter Bcl-2, Bax and Mcl-1 expression. Cell cycle analysis revealed a cell cycle arrest in early G0/G1 phase with an increase in G0/G1 cell population (70% in control cells vs. 83% in exposed cells) associated with a decrease in the S cell population (14% in control cells vs. 5.5% in exposed cells). The Ki67 labeling index also confirmed the cell cycle blockade. Our results suggest that BFA may be a potent cell cycle modulator and inducer of apoptosis in GB cell lines, and therefore may become a promising candidate for the chemotherapeutic treatment of gliomas.

Aggressive systemic mastocytosis.

Systemic mastocytosis is a rare and occasionally aggressive condition that raises major diagnostic challenges. We report a case in a 72-year-old patient in whom the diagnosis of malignant mastocytosis required two bone marrow smears and three bone marrow biopsies examined using specific staining techniques. Despite interferon therapy, a mast-cell sarcoma of the sternum developed 1 year after symptom onset, followed 1 year later by acute myeloblastic leukemia, which was rapidly fatal.