Neurotensin receptor type 2 protects B-cell chronic lymphocytic leukemia cells from apoptosis.

B-cell chronic lymphocytic leukemia (B-CLL) cells are resistant to apoptosis, and consequently accumulate to the detriment of normal B cells and patient immunity. Because current therapies fail to eradicate these apoptosis-resistant cells, it is essential to identify alternative survival pathways as novel targets for anticancer therapies. Overexpression of cell-surface G protein-coupled receptors drives cell transformation, and thus plays a critical role in malignancies. In this study, we identified neurotensin receptor 2 (NTSR2) as an essential driver of apoptosis resistance in B-CLL. NTSR2 was highly expressed in B-CLL cells, whereas expression of its natural ligand, neurotensin (NTS), was minimal in both B-CLL cells and patient plasma. Surprisingly, NTSR2 remained in a constitutively active phosphorylated state, caused not by a mutation-induced gain-of-function but rather by an interaction with the oncogenic tyrosine kinase receptor TrkB. Functional and biochemical characterization revealed that the NTSR2-TrkB interaction acts as a conditional oncogenic driver requiring the TrkB ligand brain-derived neurotrophic factor (BDNF), which unlike NTS is highly expressed in B-CLL cells. Together, NTSR2, TrkB and BDNF induce autocrine and/or paracrine survival pathways that are independent of mutation status and indolent or progressive disease course. The NTSR2-TrkB interaction activates survival signaling pathways, including the Src and AKT kinase pathways, as well as expression of the anti-apoptotic proteins Bcl-2 and Bcl-xL. When NTSR2 was downregulated, TrkB failed to protect B-CLL cells from a drastic decrease in viability via typical apoptotic cell death, reflected by DNA fragmentation and Annexin V presentation. Together, our findings demonstrate that the NTSR2-TrkB interaction plays a crucial role in B-CLL cell survival, suggesting that inhibition of NTSR2 represents a promising targeted strategy for treating B-CLL malignancy.

IgM peak independently predicts treatment-free survival in chronic lymphocytic leukemia and correlates with accumulation of adverse oncogenetic events.

We examined the significance of IgM peaks in chronic lymphocytic leukemia (CLL), including its association with newly reported MYD88, BIRC3, NOTCH1 and SF3B1 mutations. A total of 27, 25, 41 and 57 patients with monoclonal IgM or IgG peaks (IgM and IgG groups), hypogammaglobulinemia (Hypo-γ group) and normal immunoglobulin serum levels (normal-γ group) were, respectively, included. IgM peaks were mainly associated with Binet stage C and the del(17p). Biased usage of IGHV3-48 was shared by both IgM and IgG groups. IGHV3-74 and IGHV4-39 gene rearrangements were specific for IgM and IgG peaks, respectively. SF3B1, NOTCH1, MYD88 and BIRC3 mutation frequencies were 12%, 4%, 2% and 2%, respectively, being over-represented in IgM, IgG and Hypo-γ groups for SF3B1, and being equal between normal-γ and IgM groups for MYD88. Overall, 76%, 87%, 49% and 42% of cases from IgM, IgG, Hypo-γ and normal-γ groups had at least one intermediate or poor prognosis genetic marker, respectively. By multivariate analysis, IgM peaks were associated with shorter treatment-free survival independently from any other univariate poor prognosis biological parameters, including IgG peaks, Hypo-γ, IGHV status, SF3B1 mutations, cytogenetics and lymphocytosis. Therefore, as with IgG peaks, IgM peaks aggravated the natural course of CLL, with increased accumulation of adverse genetic events.

RelA and RelB cross-talk and function in Epstein-Barr virus transformed B cells.

In this study, we determined the respective roles of RelA and RelB NF-κB subunits in Epstein-Barr virus (EBV)-transformed B cells. Using different EBV-immortalized B-cell models, we showed that only RelA activation increased both survival and cell growth. RelB activity was induced secondarily to RelA activation and repressed RelA DNA binding by trapping the p50 subunit. Reciprocally, RelA activation repressed RelB activity by increasing expression of its inhibitor p100. To search for such reciprocal inhibition at the transcriptional level, we studied gene expression profiles of our RelA and RelB regulatable cellular models. Ten RelA-induced genes and one RelB-regulated gene, ARNTL2, were repressed by RelB and RelA, respectively. Apart from this gene, RelB signature was included in that of RelA Functional groups of RelA-regulated genes were for control of energy metabolism, genetic instability, protection against apoptosis, cell cycle and immune response. Additional functions coregulated by RelA and/or RelB were autophagy and plasma cell differentiation. Altogether, these results demonstrate a cross-inhibition between RelA and RelB and suggest that, in fine, RelB was subordinated to RelA. In the view of future drug development, RelA appeared to be pivotal in both classical and alternative activation pathways, at least in EBV-transformed B cells.

IGHV gene features and MYD88 L265P mutation separate the three marginal zone lymphoma entities and Waldenström macroglobulinemia/lymphoplasmacytic lymphomas.

To clarify the relationships between marginal zone lymphomas (MZLs) and Waldenström macroglobulinemia/lymphoplasmacytic lymphomas (WM/LPLs), immunoglobulin heavy chain variable gene (IGHV) features were analyzed and the occurrence of MYD88 L265P mutations was identified in a series of 123 patients: 53 MZLs from the spleen (SMZLs), 11 from lymph nodes (NMZLs), 28 mucosa-associated lymphatic tissue (MALT) lymphomas and 31 WM/LPLs. SMZLs were characterized by overrepresentation of IGHV1-2 gene rearrangements with a canonical motif, without selection pressure and with long CDR3 segments. NMZLs had increased frequencies of IGHV3 genes. The IGHV gene was unmutated in most cases, often with long CDR3 segments. MALT lymphomas were usually associated with a mutated IGHV gene, but with the absence of selection pressure. WM/LPLs were associated with an IGHV3-23 overrepresentation and high IGHV mutation rate, with features of selection pressure and short CDR3 segments. MYD88 L265P mutations were almost restricted exclusively to WM/LPL patients. Taken all diagnoses together, all patients with MYD88 L265P mutations had an immunoglobulin M peak and almost all patients except one had bone marrow infiltration. These results demonstrate that the history of antigen exposure of the four entities studied was different and MYD88 L265P was specifically associated with WM/LPLs. WM/LPL may thus be functionally associated with constitutive nuclear factor-κB activation.

A new Leukemia Prognostic Scoring System for refractory/relapsed adult acute myelogeneous leukaemia patients: a GOELAMS study.

A simplified prognostic score is presented based on the multivariate analysis of 138 refractory/relapsed acute myeloid leukaemia (AML) patients (median age 55 years, range: 19-70) receiving a combination of intensive chemotherapy+Gemtuzumab as salvage regimen. Overall, 2-year event-free survival (EFS) and overall survival (OS) were 29±4% and 36±4%, respectively. Disease status (relapse <12 months, including refractory patients), FLT3-ITD-positive status and high-risk cytogenetics were the three strongest independent adverse prognostic factors for OS and EFS in this series. We then defined three subgroups with striking different outcomes at 2 years: no adverse factor (favourable, N=36): OS 58%, EFS 45%; one adverse factor (intermediate, N=54): OS 37%, EFS 31%; two or three adverse factors (poor, N=43): OS 12%, EFS 12% (P<10(-4), P=0.001). This new simplified Leukemia Prognostic Scoring System was then validated on an independent cohort of 111 refractory/relapsed AML patients. This new simplified prognostic score, using three clinical and biological parameters routinely applied, allow to discriminate around two third of the patients who should benefit from a salvage intensive regimen in the setting of refractory/relapsed AML patients. The other one third of the patients should receive investigational therapy.

L-asparaginase-based treatment of 15 western patients with extranodal NK/T-cell lymphoma and leukemia and a review of the literature.

BACKGROUND: Extranodal natural killer (NK)/T-cell lymphoma, nasal type, and aggressive NK-cell leukemia are highly aggressive diseases with a poor outcome. PATIENTS AND METHODS: We report a multicentric French retrospective study of 15 patients with relapsed, refractory, or disseminated disease, treated with L-asparaginase-containing regimens in seven French centers. Thirteen patients were in relapse and/or refractory and 10 patients were at stage IV. RESULTS: All but two of the patients had an objective response to L-asparaginase-based treatment. Seven patients reached complete remission and only two relapsed. CONCLUSION: These data, although retrospective, confirm the excellent activity of L-asparaginase-containing regimens in refractory extranodal NK/T-cell lymphoma and aggressive NK-cell leukemia. Therefore, L-asparaginase-based regimen should be considered as a salvage treatment, especially for patients with disseminated disease. First-line L-asparaginase combination therapy for extranodal NK/T-cell lymphoma and aggressive NK-cell leukemia should be tested in prospective trials.

Identification of a novel p53-dependent activation pathway of STAT1 by antitumour genotoxic agents.

Chemotherapeutic drugs such as fludarabine*, doxorubicin or cisplatin are very potent activators of the anti-oncogene p53. Convergent studies suggest that p53 and STAT1 (signal transducer and activator of transcription 1) cooperate in the induction of cell death. We show that these drugs are also activators of STAT1 in p53-expressing cells, but not in p53-null cells. STAT1 activation was obtained in the presence of both the secretion inhibitor brefeldine A and the inhibitor of RNA synthesis, actinomycin D. p53-dependent STAT1 activation was reversed by overexpression of MDM2 and siRNAs against p53. Genetic analysis of p53 showed that expression of transcriptionally inactive p53 punctual mutants markedly increased Y701-STAT1 phosphorylation, and suggests that the p53 DNA-binding domain was alternatively involved in STAT1 activation or p53 multimerization. Immunoprecipitation experiments showed that ataxia telangiectasia mutated, p53, STAT1 and c-Abl1 (Abelson murine leukaemia viral oncogene homologue 1) were associated together. Treatment of cells with the c-Abl1 tyrosine kinase inhibitor STI571 decreased STAT1 activation by genotoxic drugs. Finally, genotoxic agents sensitized cells in response to very low doses of both interferon alpha and gamma (IFNalpha and gamma). These results show that genotoxic drugs induce STAT1 activation, an effect that depends on p53 protein but not on p53 transcriptional activity, and point to a novel pathway of STAT1 activation by genotoxic drugs, with involvement of c-Abl1 tyrosine kinase in sensitizing cells to IFN response.

Thymoma-associated pancytopenia: effectiveness of cyclosporine A.

Aplastic anemia is a rare complication of thymoma and is properly documented in only few cases. Here, we report the case of a previously healthy, 65-year-old patient who was found simultaneously to have a spindle-cell thymoma and severe hypoplastic anemia with a mild infiltration of the bone marrow by CD4+ and CD8+ T lymphocytes, CD16+ natural killer cells, and a decrease in blood CD4/CD8 ratio. Cultures of marrow erythroid progenitors demonstrated serum inhibitor. While steroids, cyclophosphamide and antilymphocyte globulin failed to improve hematopoiesis, cyclosporine A (Cy-A) led to a partial, stable remission that was sustained for 4 years. Since Cy-A has been associated with good responses in three cases of thymoma-associated red cell aplasia, we recommend its use in cases of thymoma-associated cytopenias refractory to steroids and cyclophosphamide.

B cell compartments in multiple myeloma: flow cytometric analysis of their labelling indices and Bcl-2 protein expression.

Because recent reports have suggested that non plasmacytic tumor B cells are very rare in Multiple Myeloma (MM), we tried to characterize the B lineage in this disease by comparing by flow cytometry in the PB and BM of MM patients and of controls the proliferative activity (BrdU incorporation) and the Bcl-2 expression of different B cell subsets defined by cytoplasmic light chain, CD19 or CD10 antigen expression. The labelling indices (LI) of CD19+ and CD10+ BM cells in treated patients were higher than in controls and untreated patients. Plasma cell LI (PCLI) were close to previously published values of PCLI flow assays and did not correlate with the LI of BM B cells. Bcl-2 expression by BM CD19+ and CD10+ cells in patients was inferior to controls. These results agree with previously published data about the likely polyclonal nature of most pre PC B cells in MM.

Leukemia inhibitory factor concentrations in the bone marrow plasma of healthy subjects and patients with hematologic malignancies.

Several cytokines may play a role in the pathogenesis of various hematopoietic malignancies. As cytokines work locally, we have investigated leukemia inhibitory factor (LIF) concentrations in the bone marrow plasma of healthy subjects and patients with hematopoietic malignancies by using a specific enzyme-linked immunosorbent assay. LIF levels in patient's samples were significantly higher in bone marrow plasmas (330.3 +/- 43.6 pg/ml; n = 29) than LIF levels in blood plasmas (178.9 +/- 16.8 pg/ml; n = 43) (p = 0.0006, Mann-Whitney U-test). Marrow stromal cells which constitutively produce LIF and enhance their synthesis in response to LPS and PMA might be the cell source of the bone marrow-derived LIF. No statistical difference was documented between marrow plasma LIF concentrations of 24 patients with hematological malignancies and healthy controls. At the present time, the role of LIF in the human marrow cytokine network requires further evaluation.

Spontaneous and inducible production of macrophage colony-stimulating factor by human bone marrow stromal cells.

Macrophage Colony-Stimulating Factor (M-CSF), which is permanently present in blood and human bone marrow, regulates the proliferation, differentiation and functions of cells of the mononuclear-phagocytic lineage. By using Reverse-Transcriptase Polymerase Chain Reaction (RT-PCR) we demonstrate that human marrow stromal cells express two types of M-CSF transcripts that are translated into the secreted form and the membrane anchored form. By using a specific and sensitive ELISA, we found that the spontaneous production of M-CSF by human marrow stromal cells is enhanced after stimulation with lipopolysaccharide (LPS), phorbol myristic acetate (PMA) and most interestingly by the lipidic mediator of inflammation platelet-activating factor (PAF). Thus, marrow stromal cells might represent a regulated cell source of bone marrow-derived M-CSF. These results not only emphasize the importance of the bone marrow environment in the control of human hematopoiesis but also evidence, for the first time, the potential role of PAF in the marrow cytokine network during inflammatory processes.

Cytogenetic study of 30 patients with multiple myeloma: comparison of 3 and 6 day bone marrow cultures stimulated or not with cytokines by using a miniaturized karyotypic method.

Cytogenetics in multiple myeloma (MM) cases are generally difficult to perform due to the low proliferation index of malignant plasma cells (PC) in most cases. Although IL-6 and GM-CSF stimulate the in vitro proliferation of malignant plasma cells, their usefulness for improving cytogenetic results in multiple myeloma patients remains questionable, because results which compare various culture conditions in a sufficient number of patients are not available. By using a miniaturized karyotypic method, we compared in 30 multiple myeloma patients the number and percentage of clonal abnormal mitoses obtained from 3 and 6 d bone marrow cultures performed without or with two combinations of cytokines: IL-6 + GM-CSF or IL-6 + GM-CSF + IL-2 + IL-4 + TNFalpha. The percentage of patients with an abnormal karyotype, which varied with the Durie and Salmon stage of the disease, as well as the type of numerical and structural karyotypic abnormalities that we detected, were in agreement with published results. The detection of clonal karyotypic abnormalities was better after 3d of culture without cytokine than in all other culture conditions. The higher percentage of patients at all stages of MM with an abnormal karyotype in our study (76.6%) than in previous ones (20% to 60%) is largely explained by the large number of mitoses analysed in six different culture conditions due to the use of a miniaturized karyotypic method.

Tumour necrosis factor-alpha (TNFalpha) stimulates the growth of human bone marrow stromal cells.

This study reports that TNF-alpha is a potent mitogen for human bone marrow sternal cells in vitro (assessed by [(3)H]-thymidine incorporation into DNA and cell counts). In contrast, cytokines such as IL-1alpha, IL-1beta, IL-2, IL-3, IL-4, IL-6, LIF, SCF, M-CSF, G-CSF and GM-CSF had no effect. The effect of TNF-alpha on the growth of human bone marrow stromal cells could be of importance during inflammatory processes which take place in the marrow, for example marrow fibrosis.

A "miniaturized" method for the karyotypic analysis of bone marrow or blood samples in hematological malignancies.

Standard techniques of karyotypic analysis of bone marrow or peripheral blood cells generally use large numbers of cells. Thus, the quantity of cells harvested from one bone marrow or blood puncture frequently represents a limiting factor for other assays such as molecular biology or flow cytometry, which are often essential for the diagnosis of hematological diseases. To resolve this problem, we developed a "miniaturized technique" of cytogenetic analysis that we tested on bone marrow (BM) cells from 20 patients with multiple myeloma (MM), 5 patients with acute leukemia (AL), as well as on CD34+ cells purified from the blood of 8 patients with agnogenic myeloid metaplasia (AMM). We used 3 x 10(6) BM cells from MM patients (for testing 6 different culture conditions), 10(6) BM cells from AL (2 culture conditions) and 4 x 10(3) CD34+ cells from AMM patients. In most patients, 20 good quality metaphases per slide were easily analyzed, showing that a 10-40 times reduction of the number of cells used for cytogenetics allows a reliable karyotypic analysis in hematological malignancies.