1,720,991 research outputs found
Monoclonal B-cell lymphocytosis: right track or red herring?
No full text"Monoclonal B-cell lymphocytosis (MBL), a newly recognized entity found in approximately 3% of normal persons, precedes chronic lymphocytic leukemia. However, MBLs progress into overt malignancy only in a very minor portion of cases, thus raising the clinical concern of whether and how we can discriminate at diagnosis which rare cases will evolve into a fully fledged tumor. Understanding the molecular\/biologic features underlying the risk of progression may significantly modify our strategies for correctly managing B-cell premalignant states. MBL cells bear the same chromosomal abnormalities of chronic lymphocytic leukemia. Genome-wide sequencing and animal models indicate that genetic abnormalities disrupting the control of cell growth and survival cooperate with microenvironment-triggered events, mainly represented by antigen-mediated B-cell receptor and co-receptor stimulation, to trigger and fuel clonal expansion. The initial functional activation of survival\/proliferation pathways may later become subsidized by autonomous genetic abnormalities (eg, a single mutation) affecting the same or parallel critical signaling pathway(s). (Blood. 2012;119(19):4358-4362)
Chronic lymphocytic leukemia: the pathologist's view of lymph node microenvironment
No full textChronic lymphocytic leukemia (CLL), an indolent B-cell malignancy frequently diagnosed in the elderly, is characterized by the relentless accumulation of CD5(+) monoclonal B cells that proliferate in the appropriate tissue microenvironments. Despite many advances achieved by molecular and functional studies, our knowledge of the reciprocal relationship between the CLL cell and its microenvironment at the tissue level is still largely incomplete. In this review we present the relevant current information on the tissue microenvironmental features of CLL, focusing on the events that appear to occur in the lymph node. Special attention is devoted to analyzing the properties of both neoplastic and nonneoplastic bystander cells within proliferation centers, the mysterious structures that likely represent the actual proliferative compartment. (C) 2011 Elsevier Inc. All rights reserved.Chronic lymphocytic leukemia (CLL), an indolent B-cell malignancy frequently diagnosed in the elderly, is characterized by the relentless accumulation of CD5(+) monoclonal B cells that proliferate in the appropriate tissue microenvironments. Despite many advances achieved by molecular and functional studies, our knowledge of the reciprocal relationship between the CLL cell and its microenvironment at the tissue level is still largely incomplete. In this review we present the relevant current information on the tissue microenvironmental features of CLL, focusing on the events that appear to occur in the lymph node. Special attention is devoted to analyzing the properties of both neoplastic and nonneoplastic bystander cells within proliferation centers, the mysterious structures that likely represent the actual proliferative compartment. (C) 2011 Elsevier Inc. All rights reserved. Z8 0 ZR 0 ZS 0 ZB 10"Chronic lymphocytic leukemia (CLL), an indolent B-cell malignancy frequently diagnosed in the elderly, is characterized by the relentless accumulation of CD5+ monoclonal B cells that proliferate in the appropriate tissue microenvironments. Despite many advances achieved by molecular and functional studies, our knowledge of the reciprocal relationship between the CLL cell and its microenvironment at the tissue level is still largely incomplete. In this review we present the relevant current information on the tissue microenvironmental features of CLL, focusing on the events that appear to occur in the lymph node. Special attention is devoted to analyzing the properties of both neoplastic and nonneoplastic bystander cells within proliferation centers, the mysterious structures that likely represent the actual proliferative compartment.
Xenograft models of chronic lymphocytic leukemia: problems, pitfalls and future directions.
No full text"Xenotransplantation of human tumour cells into immunodeficient mice has been a powerful pre-clinical tool in several hematologic malignancies, with the notable exception of Chronic Lymphocytic Leukemia (CLL). For several decades, this possibility was hampered by the inefficient and\/or short-term engrafment of CLL cells into available animals. The development of new generations of immunocompromised mice has allowed to partially overcome these constraints. Novel humanized animal models have been created that allow to recapitulate the pathogenesis of the disease and the complex in vivo relationships between leukemic cells and the microenvironment. In this review we discuss the development of xenograft models of CLL, how they may help elucidating the mechanisms that account for the natural history of the disease and facilitating the design of novel therapeutic approaches.
Xenograft models of chronic lymphocytic leukemia: problems, pitfalls and future directions
No full textXenotransplantation of human tumor cells into immunodeficient mice has been a powerful preclinical tool in several hematological malignancies, with the notable exception of chronic lymphocytic leukemia (CLL). For several decades, this possibility was hampered by the inefficient and/or short-term engrafment of CLL cells into available animals. The development of new generations of immunocompromised mice has allowed to partially overcome these constraints. Novel humanized animal models have been created that allow to recapitulate the pathogenesis of the disease and the complex in vivo relationships between leukemic cells and the microenvironment. In this review we discuss the development of xenograft models of CLL, how they may help elucidating the mechanisms that account for the natural history of the disease and facilitating the design of novel therapeutic approaches
Targeting the LYN/HS1 signaling axis in chronic lymphocytic leukemia
No full text"\"\\\"HS1 (Hematopoietic cell-specific Lyn substrate-1) is a cytoskeletal interactor in the B-cell receptor (BCR) signaling pathway whose phosphorylation correlates with prognosis in Chronic Lymphocytic Leukemia (CLL) patients. The differentially phosphorylated sites and the kinases that regulate HS1 activity in CLL remain poorly understood. We demonstrate that HS1 activity is differentially regulated by LYN kinase that, in a sizable subset of patients, phosphorylates HS1 on Tyrosine (Y)397, resulting in its activation. This correlates with increased cytoskeletal functionality in terms of migration, adhesion and F-actin polymerization. In these patients, LYN is also activated on Y396 residue and its inhibition with the Tyrosine Kinase Inhibitor Dasatinib abrogates HS1-Y397 phosphorylation. This results in the reduction of HS1 activation along with that of VAV1 and ERK also in the presence of microenvironmental stimuli including BCR and CXCR4 stimulation. Interestingly, targeting LYN\\\\\\\/HS1 axis in vitro with Dasatinib leads to the concomitant reduction of the cytoskeletal activity, BCR signaling and cell survival in the selected subset of patients with activated LYN\\\\\\\/HS1. Moreover in a transplantable mouse model based on the EμTCL1 transgenic mouse, LYN\\\\\\\/HS1 signaling pharmacological inhibition interferes with CLL progression and lymphoid organ infiltration. These data suggest that the LYN\\\\\\\/HS1 axis marks distinct signaling profiles and cytoskeletal-related features that may represent valuable targets for cytoskeleton-targeted therapeutic intervention in a sizable fraction of CLL patients.. . \\\"\"
Leukemic blasts secondary to myelodysplastic syndromes are molecularly programmed to differentiate into functionally mature dendritic cells
No full textDistinct Innate Immunity Pathways to Activation and Tolerance in Subgroups of Chronic Lymphocytic Leukemia with Distinct Immunoglobulin Receptors.
No full text"Subgroups of patients with chronic lymphocytic leukemia (CLL) have distinct expression profiles of Toll-like receptor (TLR) pathway-associated genes. To test the hypothesis that signaling through innate immunity receptors may influence the behavior of the malignant clone, we investigated the functional response triggered by the stimulaton of Toll-like receptors (TLRs) and NOD2 in 67 CLL cases assigned to different subgroups on the basis of IGHV gene usage, IGHV gene mutational status or B-cell receptor (BcR) stereotypy. Differences in the induction of co-stimulatory molecules and\/or apoptosis were observed in mutated vs. unmutated CLL. Different responses were also identified in subsets with stereotyped BcRs, underscoring the idea that "subset-biased" innate immunity responses may occur independently of mutational status. Additionally, differential modulation of kinase activities was induced by TLR stimulation of different CLL subgroups, revealing a TLR7-tolerant state for cases belonging to stereotyped subset #4. The distinct patterns of TLR\/NOD2 functional activity in cells from CLL subgroups defined by the molecular features of the clonotypic BcRs might prove relevant for elucidating the immune mechanisms underlying CLL natural history and for defining subgroups of patients who might benefit from treatment with specific TLR ligands.
In leukaemic CD5+ B cells the expression of BCL-2 gene family is shifted toward protection from apoptosis
No full textThis study further investigated the mechanisms that control apoptosis in leukaemic CD5+ B cells, and focused on the Bcl-2 gene family. The pattern of expression of Bcl-2, Bcl-xL, Bcl-xS and Bax genes, selected because of their interrelated role in the control of apoptosis, was analysed in a series of CD5+ B-cell chronic lymphoid leukaemias. Cells from 34 patients with chronic lymphoid leukaemia of B-cell type (23 B-chronic lymphocytic leukaemia (B-CLL) and 11 mantle cell lymphoma (MCL) in leukaemic phase) were investigated. High levels of Bcl-2 mRNA were observed by Northern blot and high levels of Bcl-2 protein were detected by cytofluorograph analysis with a specific monoclonal antibody (MAb) in all cases. Strong Bax expression was detected by RT-PCR in 20/2 3 B-CLL cases; Bax was also observed in 8/11 MCL in leukaemic phase with variable degree of intensity. In both B-CLL and MCL samples the presence of Bax protein was confirmed by cytofluorograph analysis. RT-PCR detected high levels of Bcl-xL in 16/23 BCLL and in 8/11 MCL in leukaemic phase, whereas Bcl-xS was detectable in low to trace amounts respectively in 13/23 B-CLL and in 6/11 MCL in leukaemic phase. According to the functional role of Bcl-2, Bcl-xL, Bcl-xS and Bax, these data indicate that the pattern of Bcl-2 family genes expression in leukaemic CD5+ B cells is skewed toward prevention of apoptosis and may thus favour the relentless accumulation of CD5+ leukaemic B cells
General population low-count CLL-like MBL persists over time without clinical progression, although carrying the same cytogenetic abnormalities of CLL.
No full text"Monoclonal B-cell lymphocytosis (MBL) is classified as chronic lymphocytic leukemia (CLL)-like, atypical CLL, and CD5(-) MBL. The number of B cells per microliter divides CLL-like MBL into MBL associated with lymphocytosis (usually detected in a clinical setting) and low-count MBL detected in the general population (usually identified during population screening). After a median follow-up of 34 months we reevaluated 76 low-count MBLs with 5-color flow cytometry: 90% of CLL-like MBL but only 44.4% atypical CLL and 66.7% CD5(-) MBL persisted over time. Population-screening CLL-like MBL had no relevant cell count change, and none developed an overt leukemia. In 50% of the cases FISH showed CLL-related chromosomal abnormalities, including monoallelic or biallelic 13q deletions (43.8%), trisomy 12 (1 case), and 17p deletions (2 cases). The analysis of the T-cell receptor beta (TRBV) chains repertoire showed the presence of monoclonal T-cell clones, especially among CD4(high)CD8(low), CD8(high)CD4(low) T cells. TRBV2 and TRBV8 were the most frequently expressed genes. This study indicates that (1) the risk of progression into CLL for lowcount population-screening CLL-like MBL is exceedingly rare and definitely lower than that of clinical MBL and (2) chromosomal abnormalities occur early in the natural history and are possibly associated with the appearance of the typical phenotype. (Blood. 2011; 118(25): 6618-6625)
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