Publications (6)29.82 Total impact
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Article: The effect of FK506 on transforming growth factor beta signaling and apoptosis in chronic lymphocytic leukemia B cells.
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ABSTRACT: Loss of response to transforming growth factor-beta (TGF-beta ) is thought to contribute to the progression of chronic lymphocytic leukemia. Recent findings of over-activation of the TGF-beta signal in FKBP12-knockout mouse prompted us to investigate whether FK506, the canonical ligand of FKBP, can activate the TGF-beta signal in chronic lymphocytic leukemia. We studied 62 chronic lymphocytic leukemia samples from patients with Rai/Binet stage 0 to 4 disease. The TGF-beta signal was investigated by western blotting and flow cytometry. The levels of Bcl2-family members and death-associated-protein kinase were also investigated by western blotting, whereas apoptosis was studied in flow cytometry. Down-modulation of FKBP12 was obtained by gene silencing with short interfering RNA. Twenty-two out of 62 chronic lymphocytic leukemia samples were sensitive to TGF-beta-induced apoptosis. All but two of the responsive samples underwent apoptosis also when cultured with FK506, but not with cyclosporine. Thirteen samples that were not sensitive to TGF-beta were sensitive to FK506. Overall, response to FK506 occurred in 33 samples. FK506 induced Smad2 phosphorylation and nuclear translocation. Accordingly, death-associated-protein kinase, a transcriptional target of Smad, was induced. At the same time, Bcl-2 and Bcl-xL levels decreased whereas the levels of Bim and Bmf increased. A loss of mitochondrial membrane potential preceded caspase activation and cell death. FK506 removed FKBP12 from its binding to the TGF-beta-receptor. FKBP12 release activated the receptor-kinase activity as suggested by the enhanced levels of phospho-Smad found in cells depleted of FKBP12. Our study shows that most chronic lymphocytic leukemia cells escape the homeostatic control of TGF-beta and that FK506 restores the TGF-beta signal in a proportion of non-responsive samples. We demonstrated that FK506 activates TGF-beta receptor I kinase activity in chronic lymphocytic leukemia, which transduces apoptosis by a mitochondrial-dependent pathway.Haematologica 08/2008; 93(7):1039-48. · 6.42 Impact Factor -
Article: Selective inhibition of PED protein expression sensitizes B-cell chronic lymphocytic leukaemia cells to TRAIL-induced apoptosis.
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ABSTRACT: B-cell chronic lymphocytic leukaemia (B-CLL) cells fail to undergo apoptosis. The mechanism underlying this resistance to cell death is still largely unknown. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) effectively kills tumour cells but not normal cells, and thus represents an attractive tool for the treatment of cancer. Unfortunately, lymphocytes from B-CLL patients are resistant to TRAIL-mediated apoptosis. Thus, we aimed to study the involvement of PED, a DED-family member with a broad antiapoptotic action, in this resistance. We demonstrate that B lymphocytes obtained from patients with B-CLL express high levels of PED. Treatment of B-CLL cells with specific PED antisense oligonucleotides, a protein synthesis inhibitor or HDAC inhibitors, induced a significant downregulation of PED and sensitized these cells to TRAIL-induced cell death. These findings suggest a direct involvement of PED in resistance to TRAIL-induced apoptosis in B-CLL. It also identifies this DED-family member as a potential therapeutic target for this form of leukaemia.International Journal of Cancer 04/2007; 120(6):1215-22. · 5.44 Impact Factor -
Article: Induction of CD95 upregulation does not render chronic lymphocytic leukemia B-cells susceptible to CD95-mediated apoptosis.
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ABSTRACT: B-cell chronic lymphocytic leukemia (B-CLL) is characterized by a progressive accumulation of long-lived and well-differentiated clonal B-lymphocytes in peripheral blood, lymphoid tissue and bone marrow. Although B-CLL pathogenesis is not entirely understood, the progressive increase in lymphocyte counts coupled with the very low proportion of proliferating cells suggests that B-CLL may be primarily determined by defective apoptosis. Consistently, freshly analyzed CLL B-cells express very low levels of membrane CD95, one of the best-known receptors involved in triggering apoptosis. In this study, CD95 upregulation on CLL B-cells was induced by culturing clonal B-cells in the presence of supernatants from preactivated autologous T-lymphocytes. Intracellular cytokine staining of preactivated autologous T-lymphocytes using monoclonal antibodies (moAbs) specific for Th1 or Th2 cytokines, namely interleukin (IL)-2, IL-4, IL-5, IL-10 and interferon (IFN)-gamma, showed these cells to be positive for IL-2 and IFN-gamma. Blocking experiments using moAbs specific for IL-2 and/or IFN-gamma revealed that CD95 upregulation on CLL B-cells was mainly driven by IFN-gamma. However, CD95-expressing CLL B-cells were demonstrated to be resistant to CD95-mediated apoptosis, thus arguing against strategies aimed at exploiting CD95-mediated apoptosis for immunotherapy of B-CLL.Immunology Letters 03/2005; 97(1):131-9. · 2.53 Impact Factor -
Article: GIMEMA ALL - Rescue 97: a salvage strategy for primary refractory or relapsed adult acute lymphoblastic leukemia.
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ABSTRACT: The outcome of adult patients with acute lymphoblastic leukemia (ALL) is discouraging, only about 30% of them becoming long-term survivors. A small fraction of patients are resistant to the first line treatment, while most patients relapse within two years of achieving complete remission (CR). No standard treatment exists for refractory or relapsed patients. The GIMEMA group designed a phase II trial for adult ALL patients with refractory or relapsed disease. Patients aged >15 years with primary refractory or relapsed ALL were eligible for this study. The salvage strategy included a single high dose of idarubicin combined with high dose cytarabine, followed by consolidation therapy leading to a stem cell transplant procedure according to donor availability. From 1998 to 2002, 135 patients were enrolled. Seventy-five patients (55%) achieved CR, including 12 Philadelphia-positive cases; 44 patients had persistent leukemia and 16 died during reinduction. Fifty patients received a stem cell transplant: 19 from an HL-A identical sibling, 16 from an unrelated donor, 7 from a haploidentical relative, 2 received cord blood, and 6 had an autotransplant. The median disease-free and overall survival were both short (5.0 and 6.4 months, respectively); however, after a median follow-up of 40 months, 13 patients are alive, 10 of whom are free of disease (9 transplanted), while 3 are alive with leukemia. Interpretation and The treatment induced CR in a high percentage of poor prognosis patients, thus rendering a transplant procedure feasible in most of them. However, significant rates of transplant-related mortality and post-transplant relapse encourage the search for more effective and less toxic conditioning regimens.Haematologica 02/2004; 89(2):145-53. · 6.42 Impact Factor -
Article: Effects of preactivated autologous T lymphocytes on CD80, CD86 and CD95 expression by chronic lymphocytic leukemia B cells.
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ABSTRACT: Profound immune dysfunction is a constant feature in B-cell chronic lymphocytic leukemia (B-CLL) patients. Immunological abnormalities include hypogammaglobulinemia, impaired immunoglobulin class switching and diminished germinal center formation. This state of immune suppression renders B-CLL patients highly susceptible to infections, which contribute greatly to morbidity and mortality in this disease. Impaired T cell function in B-CLL is well-documented and has been suggested to result from inhibitory effects exerted by malignant B lymphocytes. Because the presence of leukemic cells may represent a major obstacle to efficient T cell activation, T lymphocytes were separated from CLL B cells, stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin for 4h, and then cocultured with autologous leukemic B cells both at a 1:1 ratio or at the same ratio as in vivo for 24-40 h. CLL B cell expression of CD86 and CD95 was markedly upregulated using this approach, whereas CD80 expression was augmented only in a minority of patients; these effects were partially preserved even when preactivated T cells were rechallenged with CLL B cells at the same low T/B cell ratio as that observed in vivo. Finally, CD80 upregulation on CLL B cells appeared to be mainly dependent on CD40L-mediated stimulation, whereas CD86 and CD95 expression was efficiently augmented by soluble factors released by preactivated T lymphocytes. In conclusion, efficient activation of T lymphocytes in B-CLL may be achieved which, in turn, may result in enhanced antigen-presenting capacity and susceptibility to apoptosis of leukemic cells via CD86 and CD95 upregulation, respectively.Leukemia and Lymphoma 12/2003; 44(11):1963-71. · 2.58 Impact Factor -
Article: Acute lymphoblastic leukemia in the context of a disorder resembling X-linked lymphoproliferative (XLP) syndrome.
Haematologica 09/2002; 87(8):ELT36. · 6.42 Impact Factor
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