1,721,093 research outputs found
ANALYSIS OF SIGNALING PROFILES IN CHRONIC LYMPHOCYTIC LEUKEMIA
No full textChronic lymphocytic leukemia (CLL) patients exhibit a variable clinical course that reflects biological differences driven by intrinsic defects as well as external cues from the microenvironment. These events converge on the activation of regulatory signaling pathways involved in processes promoting resistance to apoptosis and overturning the control of proliferation. Indeed, CLL physiopathology is entwined with its microenvironment and the statuses of proteins involved in signal transduction represent a unique series of markers dynamically determined from microenvironment, indicating the cell capability to transduce information. To gain insights into the pathogenic role and clinical significance of microenvironment signals in CLL, we analyzed the phosphorylation status of proteins on the road of B-cell receptor (BCR) pathway, which represents a prominent pathogenic mechanism in CLL, using a multiparametric flow cytometry-based assay. This method allows to measure, simultaneously and quantitatively, at the single cell level, both extracellular surface markers and changes in signaling proteins in response to extracellular stimuli, thus providing a dynamic view of signaling responses to microenvironment. We showed that higher responsiveness of BCR signaling-protein was associated with poor clinical outcomes and signal profiles distinguished patients with indolent disease from those with a poor clinical course. Time-to-event modeling utilizing phosphorylation-status data identified Erk1/2 responsiveness as a significant, independent predictor of CLL disease progression. This result was independently confirmed in other test cohorts of CLL patients. Of interest, the presence of CXCR4 co-stimulation, another key pathway of CLL microenvironment cross- talk, induced a higher Erk1/2 phosphorylation response than the BCR alone. Also, Erk1/2 responsiveness induced by the BCR and CXCR4 co-stimulation was more powerful in discriminating different disease courses. Our data showed the utility of this flow cytometry-based assay for identification and independent verification of signaling profiles associated with prognosis in CLL. Moreover, these data support the pathogenic role and clinical relevance of microenvironment signals, highlighting the prominent role of BCR signaling, and suggest a critical role of Erk activation in CLL physiopathology
Signaling pathways activated by the B-cell receptor in chronic lymphocytic leukemia
No full textOver the past decade, several features of the B-cell receptor (BCR) complex have emerged as major markers for prognostic classification of B-cell chronic lymphocytic leukemia (B-CLL). In particular, the absence of somatic mutations within the immunoglobulin variable heavy chain genes (IGHV), the presence of ZAP-70 and a higher ability of the BCR to translate signals within the cell have been associated with an aggressive clinical course. Indeed, the stratification of patients with B-CLL based on BCR features suggests that heterogeneity of B-CLL clinical courses may reflect BCR signaling differences that have arisen during the evolution of leukemia. Therefore, characterizing BCR signaling profiles may help to identify signaling markers useful for patient stratification, disease monitoring and therapeutic targeting in B-CLL
Early decrease of interferon-gamma+ and interleukin-2+ T cells during combination treatment with interferon-alpha and ribavirin in patients with chronic hepatitis C.
No full textEarly decrease of interferon-gamma+ and interleukin-2+ T cells during combination treatment with interferon-alpha and ribavirin in patients with chronic hepatitis
Bone marrow-derived stromal cells inhibit spontaneous apoptosis and induce proliferation in blasts of T acute lymphoblastic leukaemia: the role of interleukin 7
No full textCell lineage-specific and developmental stage-specific controls of MHC class-II-antigen expression.
No full textIn this report we present evidence and we review data from our laboratory which indicate the genetic complexity of regulatory mechanisms controlling MHC class-II-gene expression. The MHC class-II genes can be expressed in 2 ways: in a constitutive fashion, as in B cells, and in an inducible fashion, as in macrophages, endothelial cells and certain tumors. In both cases the regulatory controls are mainly exerted at transcriptional level as a result of interactions between cis-acting regulatory DNA elements and trans-acting factors. The constitutive class-II-gene expression in B cells is under the control of developmentally regulated trans-acting factors with activator function and encoded by a series of genes, the AIR genes, one of which has been mapped in the mouse on chromosome 16. Interestingly, these regulatory mechanisms are conserved across species for at least 70 million years, because murine AIR-gene products can complement AIR gene defects of human B-cell mutants. The constitutive B-cell phenotype behaves as a dominant trait up to the plasma cell stage in which class-II-gene expression is lost because of the activation of suppressor factors which repress transcription and which, in turn, behave as a dominant trait in somatic cell hybrids between B cells and plasma cells. Thus positive and negative signals regulating class-II-gene expression may behave as dominant or recessive traits, depending upon the particular developmental stage of the cell in which they operate. The mechanisms controlling class-II expression in inducible cells are distinct from those mediating constitutive expression. Indeed, induction of these genes is not sufficient to complement AIR-gene defects in hybrids between macrophages and class-II-negative mutant B cells. In contrast, constitutive expression is dominant in hybrids between class-II-positive B cells and macrophages, suggesting that in uninduced cells class-II-gene activation does not take place more because of lack of activator factors than because of the presence of constitutive transcriptional suppressors. On the basis of these results, we propose a model for developmentally controlled MHC class-II-gene expression during ontogeny
Phospho-Specific Flow Cytometry Reveals Signaling Heterogeneity in T-Cell Acute Lymphoblastic Leukemia Cell Lines
Full text linkSeveral signaling pathways are aberrantly activated in T-ALL due to genetic alterations of their components and in response to external microenvironmental cues. To functionally characterize elements of the signaling network in T-ALL, here we analyzed ten signaling proteins that are frequently altered in T-ALL -namely Akt, Erk1/2, JNK, Lck, NF-κB p65, p38, STAT3, STAT5, ZAP70, Rb- in Jurkat, CEM and MOLT4 cell lines, using phospho-specific flow cytometry. Phosphorylation statuses of signaling proteins were measured in the basal condition or under modulation with H(2)O(2), PMA, CXCL12 or IL7. Signaling profiles are characterized by a high variability across the analyzed T-ALL cell lines. Hierarchical clustering analysis documents that higher intrinsic phosphorylation of Erk1/2, Lck, ZAP70, and Akt, together with ZAP70 phosphorylation induced by H(2)O(2), identifies Jurkat cells. In contrast, CEM are characterized by higher intrinsic phosphorylation of JNK and Rb and higher responsiveness of Akt to external stimuli. MOLT4 cells are characterized by higher basal STAT3 phosphorylation. These data document that phospho-specific flow cytometry reveals a high variability in intrinsic as well as modulated signaling networks across different T-ALL cell lines. Characterizing signaling network profiles across individual leukemia could provide the basis to identify molecular targets for personalized T-ALL therapy
DEATH RECEPTOR 3 EXPRESSION AND SERUM LEVEL OF SOLUBLE TL1A CORRELATE WITH INDOLENT, EARLY STAGE B-CELL CHRONIC LYMPHOCYTIC LEUKEMIA
No full textIntroduction. B-cell chronic lymphocytic leukemia (B-CLL) accounts for approximately 30% of leukemia diagnosed in the Western coun- tries and shows an increasing incidence with the age of the popula- tion. Analysis of survival times has led to the establishment of stag- ing systems according to various prognostic markers, including Rai stage, IGHV mutational status, expression of CD38 and Zap70. Clin- ically, B-CLL is a heterogeneous disease with variable presentation and evolution. Two major subtypes can be distinguished, indolent and aggressive, which require different treatment strategies. Howev- er, prediction of the clinical course of individual patients with the same stage and risk group remains variable. Receptors of the TNFR superfamily play a fundamental role in promoting the growth of B-cell chronic lymphocytic leukemia. Death receptor (DR) 3 is a TNFR- superfamily member expressed in lymphocyte-enriched tissues. DR3 and its ligand, TNF-like ligand 1A (TL1A), are implicated in regulato- ry mechanisms of adaptive immune response under physiological and pathological settings. Recently, we have demonstrated that DR3 is expressed on the surface of B cell receptor (BCR)-stimulated B cells and interaction of DR3 with TL1A reduces proliferation of suboptimally activated healthy B cells in vitro, without affecting cell survival. These findings prompted us to examine the expression of DR3 and TL1A in B-CLL and their possible role as risk factors for disease progression. Methods. DR3 surface expression of 37 B-CLL samples was measured by flow cytometry at baseline and following stimulation with F(ab’)2 anti-human IgM conjugated to latex microspheres. TL1A serum lev- els of 26 B-CLL samples were measured by ELISA. Correlation analy- sis with clinical and biological parameters were performed using GraphPad Prism software. Results. Here, our preliminary results show that DR3 is expressed on the surface of activated CLL B cells and TL1A is present in the serum of B-CLL patients. Moreover, we show that BCR-induced DR3 expression is more frequently detected in sam- ples with indolent, early-stage disease (Rai 0). The relevance of these findings has been confirmed by serum TL1A measurement showing that higher serum levels of TL1A are more frequently detected in B- CLL patients with favorable prognostic parameters (i.e. absence of CD38 expression) and early-stage disease. Conclusions. Taken togeth- er, these findings suggest that in B-CLL the TL1A/DR3 modulatory function on cell metabolism, in the presence of antigen stimulation, is a feature of indolent, early-stage disease. Thus, we can assume that these factors could be useful in monitoring disease activity and may be of prognostic relevance in B-CLL
Evidence for a trans-acting activator function regulating the expression of the human CD5 antigen
No full textInterspecies somatic cell hybrids were generated by fusing the mouse T-lymphoma cell line, BW5147, with normal human T lymphocytes at different stages of differentiation. Thymocytes, activated peripheral T lymphocytes, or an activated T-cell clone were used as human partners, respectively, in three independent fusions. Irrespective of the human cell partner used for fusion, a certain number of hybrids lost CD5 surface expression over a period of time in culture. Analysis at the phenotype and genetic level showed that lack of CD5 expression was due neither to segregation of human autosome 11, on which the CD5 gene has been mapped, nor to deletion of the CD5 structural gene. Furthermore, loss of CD5 surface expression correlated with the absence of specific mRNA. Since these hybrids preferentially segregate human chromosomes, these results indicate the existence of a non-syntenic trans-active locus, or loci, positively controlling the expression of the human CD5 gene
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