Incidence and outcome of BCR-ABL mutated chronic myeloid leukemia patients who failed to tyrosine kinase inhibitors.

Purpose: To assess the incidence of BCR-ABL kinase domain (KD) mutation detection and its prognostic significance in chronic phase chronic myeloid leukemia (CP-CML) patients treated with tyrosine kinase inhibitors (TKIs).

Patients And Methods: We analyzed characteristics and outcome of 253 CP-CML patients who had at least one mutation analysis performed using direct sequencing. Of them, 187 patients were early CP (ECP) and 66 were late CP late chronic phase (LCP) and 88% were treated with Imatinib as first-line TKI.

Dasatinib-Loaded Erythrocytes Trigger Apoptosis in Untreated Chronic Myelogenous Leukemic Cells: A Cellular Reservoir Participating in Dasatinib Efficiency.

Dasatinib is an ABL1 tyrosine kinase inhibitor (TKI) with a short in vivo plasmatic half-life but with good efficiency, which is not fully understood. We investigated the possibility that circulating erythrocytes store and then provide dasatinib to target cells. In vitro coincubation of dasatinib-treated cells with naïve leukemic cells followed by analysis of kinase inhibition, apoptosis induction, fluorescent molecule exchanges, and dasatinib dosage were performed.

A new mechanism of resistance to ABL1 tyrosine kinase inhibitors in a BCR-ABL1-positive cell line.

Tyrosine kinase inhibitors (TKI) constitute the frontline treatment for chronic myeloid leukemia patients. Dasatinib, a second-generation TKI, was developed to overcome TKI resistances. However, dasatinib resistances are also described but remain less characterized.

Synergistic cooperation between ABT-263 and MEK1/2 inhibitor: effect on apoptosis and proliferation of acute myeloid leukemia cells.

In spite of intensive research to improve treatment of acute myeloid leukemia (AML) more than half of all patients continue to develop a refractory disease. Therefore there is need to improve AML treatment. The overexpression of the BCL-2 family anti-apoptotic members, like BCL-2 or BCL-xL has been largely reported in lymphoid tumors but also in AML and other tumors.

Telomerase functions beyond telomere maintenance in primary cutaneous T-cell lymphoma.

Telomere erosion may be counteracted by telomerase. Here we explored telomere length (TL) and telomerase activity (TA) in primary cutaneous T-cell lymphoma (CTCL) by using quantitative polymerase chain reaction and interphase quantitative fluorescence in situ hybridization assays. Samples from patients with Sézary syndrome (SS), transformed mycosis fungoides (T-MF), and cutaneous anaplastic large cell lymphoma were studied in parallel with corresponding cell lines to evaluate the relevance of TL and TA as target candidates for diagnostic and therapeutic purposes.

A single nucleotide polymorphism in cBIM is associated with a slower achievement of major molecular response in chronic myeloid leukaemia treated with imatinib.

Purpose: BIM is essential for the response to tyrosine-kinase inhibitors (TKI) in chronic myeloid leukaemia (CML) patients. Recently, a deletion polymorphism in intron 2 of the BIM gene was demonstrated to confer an intrinsic TKI resistance in Asian patients. The present study aimed at identifying mutations in the BIM sequence that could lead to imatinib resistance independently of BCR-ABL mutations.

Cyclopamine cooperates with EGFR inhibition to deplete stem-like cancer cells in glioblastoma-derived spheroid cultures.

Putative cancer stem cells have been identified in glioblastoma (GBM), associated with resistance to conventional therapies. Overcoming this resistance is a major challenge to manage this deadly brain tumor. Epidermal growth factor receptor (EGFR) is commonly amplified, over-expressed, and/or mutated in GBM, making it a compelling target for therapy.

ABT-737 increases tyrosine kinase inhibitor-induced apoptosis in chronic myeloid leukemia cells through XIAP downregulation and sensitizes CD34(+) CD38(-) population to imatinib.

Chronic myeloid leukemia (CML) tumorigenicity is driven by the oncogenic BCR-ABL tyrosine kinase. Specific tyrosine kinase inhibitors (TKI) have been designed and are now used for the treatment of CML. These TKI induce apoptosis in leukemic cells in a BIM-dependent mechanism.

Autophagy inhibition cooperates with erlotinib to induce glioblastoma cell death.

Gliomas are the most common malignant primary brain tumors in adults. The median survival never exceeds 12 months, owing to inherent resistance to both radio and chemotherapies. Epidermal Growth Factor Receptor (EGFR) is amplified, overexpressed, and/or mutated in glioblastomas (GBM), making it a rational for therapy.

Recombinant differential anchorage probes that tower over the spatial dimension of intracellular signals for high content screening and analysis.

Recombinant fluorescent probes allow the detection of molecular events inside living cells. Many of them exploit the intracellular space to provide positional signals and, thus, require detection by single cell imaging. We describe here a novel strategy based on probes capable of encoding the spatial dimension of intracellular signals into "all-or-none" fluorescence intensity changes (differential anchorage probes, DAPs).

Evidence that resistance to nilotinib may be due to BCR-ABL, Pgp, or Src kinase overexpression.

Targeting the tyrosine kinase activity of Bcr-Abl is an attractive therapeutic strategy in chronic myeloid leukemia (CML) and in Bcr-Abl-positive acute lymphoblastic leukemia. Whereas imatinib, a selective inhibitor of Bcr-Abl tyrosine kinase, is now used in frontline therapy for CML, second-generation inhibitors of Bcr-Abl tyrosine kinase such as nilotinib or dasatinib have been developed for the treatment of imatinib-resistant or imatinib-intolerant disease. In the current study, we generated nilotinib-resistant cell lines and investigated their mechanism of resistance.

Overexpression of high molecular weight FGF-2 forms inhibits glioma growth by acting on cell-cycle progression and protein translation.

In order to clarify the role of HMW FGF-2 in glioma development and angiogenesis, we over-expressed different human FGF-2 isoforms in C6 rat glioma cell line using a tetracycline-regulated expression system. Phenotypic modifications were analyzed in vitro and compared to untransfected cells or to cells over-expressing 18 kDa FGF-2 or all FGF-2 isoforms. In particular, we demonstrate that HMW FGF-2 has unique features in inhibiting glioma cell proliferation.

Triptolide cooperates with chemotherapy to induce apoptosis in acute myeloid leukemia cells.

Objective: Triptolide has shown antitumor activity in a broad range of solid tumors and on leukemic cells in vitro.

Materials And Methods: The THP1 cell line and primary acute myeloid leukemia (AML) cells were cultured with triptolide alone or in association with AraC or idarubicin in increasing concentrations. Apoptosis was measured by flow cytometry using DiOC6(3) for the cell line and fluorescein isothiocyanateAnnexin-V and CD45 labeling for fresh blast cells.

Imatinib and nilotinib induce apoptosis of chronic myeloid leukemia cells through a Bim-dependant pathway modulated by cytokines.

It is an important challenge to better understand the mechanisms of tyrosine kinase inhibitors-induced apoptosis in CML cells. Thus, we have investigated how this apoptosis can be modulated by extracellular factors. Apoptosis induced by imatinib and nilotinib was determined in BCR-ABL expressing cell lines and primary CML CD34+ cells.

Hypoxia-inducible factor-1alpha, a key factor in the keratinocyte response to UVB exposure.

Hypoxia-inducible factor-1 (HIF-1) is a major transcription factor sensitive to oxygen levels, which responds to stress factors under both hypoxic and nonhypoxic conditions. UV irradiation being a common stressor of skin, we looked at the effect of UVB on HIF-1alpha expression in keratinocytes. We found that UVB induces a biphasic HIF-1alpha variation through reactive oxygen species (ROS) generation.

Proteasome inhibition specifically sensitizes leukemic cells to anthracyclin-induced apoptosis through the accumulation of Bim and Bax pro-apoptotic proteins.

Proteasome inhibitors are a novel class of compounds that might increase sensitivity to chemotherapy for acute myeloid leukemia (AML). We quantified apoptosis in THP-1 cells incubated with idarubicin (IDA) alone or together with a low concentration of MG132 or bortezomib. The combination of both drugs yielded a percentage of apoptotic cells that was significantly higher than the additive effect of both drugs administered separately (p < 0.

Activation of mesangial cells by platelets in systemic lupus erythematosus via a CD154-dependent induction of CD40.

Background: Platelets are potential contributors to glomerular injury via the release of chemotactic and/or mitogenic mediators upon activation or through direct CD154/CD40-dependent interaction with cell components of the glomerulus. We examined whether platelets could activate mesangial cells and the potential role of the platelet-associated CD154.

Methods: Thrombin-activated platelets from systemic lupus erythematosus (SLE) patients or from disease or healthy controls were grown with human mesangial cells in the presence or not of a neutralizing anti-CD154 antibody either in contact or in a noncontact setting, the platelets and mesangial cells being separated by a pore size semipermeable membrane.

Oxygen concentration influences mRNA processing and expression of the cd34 gene.

CD34 is a cell surface glycoprotein expressed on hematopoietic stem and progenitor cells that disappears with their maturation. This gene is transcribed in two alternatively spliced mRNAs that encode full length and truncated form of CD34 cell surface antigen. Some publications suggested that CD34 full length plays a role in the maintenance of their self renewal capacity.

Very low O2 concentration (0.1%) favors G0 return of dividing CD34+ cells.

Physiological bone marrow oxygen concentrations are everywhere lower than 4% and almost null in some areas. We compared the effects of 20%, 3%, and 0.1% O2 concentrations on cord blood CD34+ cell survival, cycle, and functionality in serum-free cultures for 72 hours with or without interleukin-3 (IL-3).

From molecular characteristics to cellular events in apoptosis-resistant HL-60 cells.

The ability to induce apoptosis in tumor cells is critical to elicit a positive response to cytotoxic chemo-therapy. In this study, we investigated the effect of the topoisomerase I inhibitors camptothecin and SN-38, known to cause an unusual form of DNA damage, on apoptotic pathways using the leukemic cell line HL-60 and its vincristine-resistant variant HL-60 VCR. Both camptothecin and SN-38 induced high levels of apoptosis in sensitive cells when compared to the multidrug-resistant ones.

Overproduction of BCR-ABL induces apoptosis in imatinib mesylate-resistant cell lines.

Background: Imatinib mesylate, a BCR-ABL tyrosine kinase inhibitor, induces apoptosis in chronic myeloid leukemia cells. Resistance to imatinib is currently the most important concern of this treatment. One of the main mechanisms of this resistance is overexpression of BCR-ABL.

Rapid detection of phosphotyrosine proteins by flow cytometric analysis in Bcr-Abl-positive cells.

Background: Constitutive tyrosine phosphorylation derived from Bcr-Abl kinase activity is the major characteristic of Bcr-Abl positive cells. In this study, we developed a method to detect the phosphotyrosine proteins by flow cytometry and we asked whether phosphorylation was affected by imatinib mesylate treatment.

Methods: Cells were treated or not with imatinib mesylate, fixed and permeabilized by PFA followed by saponin, then stained with anti-phosphotyrosine (p-tyr) monoclonal antibody and analyzed by flow cytometry.

Simultaneous maintenance of human cord blood SCID-repopulating cells and expansion of committed progenitors at low O2 concentration (3%).

In the present work, we tested the hypothesis that liquid cultures (LCs) of cord blood CD34+ cells at an appropriate low O2 concentration could simultaneously allow colony-forming cell (CFC) expansion and nonobese diabetic/severe combined immunodeficiency mice-repopulating cell (SRC) maintenance. We first found that 3% was the minimal O2 concentration, still allowing the same rate of CFC expansion as at 20% O2. We report here that 7-day LCs of cord blood CD34+ cells at 3% O2 maintain SRC better than at 20% O2 and allow a similar amplification of CFCs (35- to 50-fold) without modifying the CD34+ cell proliferation.

Platelet-associated CD154 in immune thrombocytopenic purpura.

CD40-ligand (CD154) is expressed on activated CD4+ T lymphocytes and is essential for the T cell-dependent activation of B lymphocytes. CD154 is also expressed at the activated platelet surface. In this study, we show that platelet-associated CD154 is increased in immune thrombocytopenic purpura (ITP), a disease characterized by an autoimmune response against proteins of the platelet membrane.