Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    In: Blood, American Society of Hematology, Vol. 112, No. 11 ( 2008-11-16), p. 1616-1616
    Abstract: Heat shock proteins (Hsp) are increasingly employed as therapeutic targets in various solid tumors and leukemias. We have recently shown that Hsp32 is expressed in leukemic cells and serves as a survival-factor and molecular target in Ph+ chronic myeloid leukemia. In the present study, we examined the expression and functional role of Hsp32 in acute lymphoblastic leukemia (ALL). Leukemic cells were obtained from patients with Ph+ ALL (n=5) and Ph− ALL (n=5). In addition, Ph+ ALL cell lines (Z-119, BV-173, TOM-1, NALM-1) and Ph− ALL cell lines (RAJI, RAMOS, REH, BL-41) were used. As assessed by immunocytochemistry and qRT-PCR, leukemic cells were found to express the Hsp32 protein as well as Hsp32 mRNA in all patients and in all cell lines examined. The Hsp32-inductor hemin was found to promote the expression of Hsp32 in leukemic cells. To determine the functional role of Hsp32 in lymphoblasts, an siRNA against Hsp32 was applied. The siRNA-induced knock down of Hsp32 in RAJI cells was found to be associated with reduced growth and with an increase in apoptotic cells compared to a control siRNA against luciferase (p & lt;0.05). In a next step, two pharmacologic inhibitors of Hsp32, pegylated zinc protoporphyrine (PEG-ZnPP) and styrene maleic acid-micelle-encapsulated ZnPP (SMA-ZnPP), were applied. As assessed by 3H-thymidine uptake experiments, both drugs were found to inhibit proliferation in the BCR/ABL+ cell lines Z-119, BV-173, and TOM-1, and in the BCR/ABL-negative ALL cell lines RAJI, RAMOS, REH, and BL-41. The effects of PEG-ZnPP and SMA-ZnPP were dose-dependent with IC50 values ranging between 1 and 10 μM, and were found to be associated with apoptosis as determined by microscopy as well as by flow cytometry and AnnexinV-staining. In NALM-1 cells, PEG-ZnPP and SMA-ZnPP also produced apoptosis and growth arrest, but the IC50 for SMA-ZnPP was slightly higher compared to other cell lines (20 μM). Effects of Hsp32-targeting drugs were also observed in primary leukemic cells obtained from patients with Ph+ ALL and Ph− ALL, with IC50 values ranging between 1 and 10 μM. No major differences were found when comparing results in imatinib-sensitive and imatinib-resistant patients. In drug combination experiments, Hsp32-targeting drugs were found to cooperate with imatinib and with AMN107 (nilotinib) in producing growth-inhibition and apoptosis in all Ph+ ALL cell lines tested. Furthermore, we were able to demonstrate strong cooperative antileukemic effects when applying Hsp32-targeting drugs in combination with bendamustine. Overall, these results suggest that Hsp32 may be a novel molecular target in ALL.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2008
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    In: Blood, American Society of Hematology, Vol. 122, No. 21 ( 2013-11-15), p. 1518-1518
    Abstract: The International Prognostic Scoring System (IPSS) is commonly used for predicting the outcome of myelodysplastic syndrome (MDS) patients. Recently, a Revised IPSS (IPSS-R) has been developed to address the limitations of IPSS. IPSS-R identifies five different categories and stratifies patients better than IPSS. Although transfusion dependency is associated with inferior survival outcome, it has not been included in the risk stratification of IPSS-R mainly due to limited availability of transfusion data on patients used for deriving the IPSS-R. Aim To evaluate the impact of RBC transfusion on survival outcome in IPSS-R subgroups and assess the validity of IPSS-R in an independent cohort of patients. Materials and Methods To match the patient selection criteria used for generating the IPSS-R scoring system, primary MDS patients who were not treated with disease modifying agents or stem cell transplantation were included for this analysis. The impact of RBC transfusion on overall survival (OS) was assessed in IPSS-R subgroups. RBC transfusion dependency was defined as transfusion of at least 1 unit/8 weeks for at least 4 months. Results A total of 182 patients were included in this analysis. Their median age was 73 years (21 to 91 years) and 66% patients were male. 106 patients were in the Very Low or Low risk groups (termed ‘lower risk'). The median OS of IPSS-R Very Low, Low, Intermediate, High and Very High risk groups was 87.1, 63.9, 24.5, 17.2 and 7.8 months, respectively (Fig.1. p 〈 0.0001), consistent with previously published results (Greenberg et al, Blood 2012). Of the 182 patients, 115 (63%) patients were RBC transfusion dependent. RBC transfusion dependency was more frequent in Very High (18/18, 100%), High (25/28, 89%) and Intermediate (21/31, 68%) risk groups as compared to lower risk IPSS-R groups: Low (35/67, 52%) and Very Low (17/39, 43%). The mean pre-transfusion Hb was 79.1 ±12.3 gm/L, and the trigger for transfusion was Hb ≤90, 〉 90 to ≤100 and 〉 100 gm/L in 83%, 11% and 6% of episodes, respectively. In a multivariate analysis, RBC-transfusion dependency (HR 3.18; P 〈 0.0001) was associated with poor survival, independent of the IPSS-R category and age at diagnosis (Table 2). The median OS of transfusion-dependent patients (n=115) was significantly lower (23.8 vs. 117.8 months; p 〈 0.0001) than that of transfusion-independent patients (n=67). As the majority of IPSS-R higher risk patients were transfusion dependent, we restricted further assessment to IPSS-R lower risk groups. The median OS between Low and Very Low risk group was not significantly different (87.1 vs Low 63.2 months; p=0.1), hence they were grouped together. The median OS of transfusion-dependent lower risk IPSS-R patients (n=52) was significantly shorter than that of transfusion-independent (n=54) patients (52.7 vs 122.5 months; p=0.001). Conclusions We have demonstrated that transfusion dependency is associated with inferior survival even in Very Low and Low risk IPSS-R group patients. This warrants further refinement of IPSS-R scoring system specifically for lower risk group patients. IPSS-R scoring system is validated in our independent cohort of patients. Disclosures: Hiwase: Novartis Australia: Research Funding; Celgene Australia: Research Funding.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2013
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    In: Oncotarget, Impact Journals, LLC, Vol. 5, No. 5 ( 2014-03-15), p. 1198-1211
    Type of Medium: Online Resource
    ISSN: 1949-2553
    URL: Issue
    Language: English
    Publisher: Impact Journals, LLC
    Publication Date: 2014
    detail.hit.zdb_id: 2560162-3
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Online Resource
    Online Resource
    American Society of Hematology ; 2002
    In:  Blood Vol. 100, No. 3 ( 2002-08-01), p. 1105-1106
    In: Blood, American Society of Hematology, Vol. 100, No. 3 ( 2002-08-01), p. 1105-1106
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2002
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    In: Blood, American Society of Hematology, Vol. 92, No. 9 ( 1998-11-01), p. 3362-3367
    Abstract: The number of genetic lesions necessary to generate leukemia in humans is unknown, but it is possible that certain specific abnormalities, eg, fusion genes, known to be associated with acute and chronic leukemia are produced relatively frequently in human cells but require other events to occur before the leukemia becomes manifest. We investigated this possibility by studying peripheral blood leukocytes from normal individuals and various hematopoietic cell lines for the presence and expression of the p210 and the p190 types of the BCR-ABL gene associated with chronic myeloid leukemia (CML) and acute lymphoblastic leukemia. We used two-step reverse transcriptase-polymerase chain reaction (RT-PCR) assays in which batches of 108 cells per sample were tested in 40 replicate reactions. We estimate that this assay is 1.5 logs more sensitive than the two-step RT-PCR assays that we use routinely to assess minimal residual disease. BCR-ABL fusion gene transcripts of various configurations were found in circulating leukocytes from 12 of the 16 healthy adults analyzed. Transcripts with an e1a2 junction (p190 BCR-ABL) were present in 11 and p210-type transcripts with b2a2 and/or b3a2 junctions were detected in 4 individuals. The same RT-PCR assays in non-CML cell lines showed the presence of classical or aberrant p210-type mRNA in 3 of 7 lines and of p190-type transcripts in all 7 lines of hematopoietic origin (HL60, KG1, U937, Kasumi, Jurkat, JVM13, and JVM25), whereas the NIH3T3 murine fibroblast line was reproducibly negative for these fusion genes. These findings confirm and extend previous reports on the detection of leukemia-associated genes in normal leukocytes and suggest that certain fusion genes are generated relatively frequently in hematopoietic cells, but only infrequently do the cells acquire the additional changes necessary to produce leukemia in humans. Although there is only a small probability that such innocent BCR-ABL–carrying leukocytes are detected by conventional RT-PCR assays, they may be the source of some sporadically positive tests in leukemia patients in long-term remission. © 1998 by The American Society of Hematology.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 1998
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    In: Blood, American Society of Hematology, Vol. 118, No. 13 ( 2011-09-29), p. 3634-3644
    Abstract: We prove that the SH2-containing tyrosine phosphatase 1 (SHP-1) plays a prominent role as resistance determinant of imatinib (IMA) treatment response in chronic myelogenous leukemia cell lines (sensitive/KCL22-S and resistant/KCL22-R). Indeed, SHP-1 expression is significantly lower in resistant than in sensitive cell line, in which coimmunoprecipitation analysis shows the interaction between SHP-1 and a second tyrosine phosphatase SHP-2, a positive regulator of RAS/MAPK pathway. In KCL22-R SHP-1 ectopic expression restores both SHP-1/SHP-2 interaction and IMA responsiveness; it also decreases SHP-2 activity after IMA treatment. Consistently, SHP-2 knocking-down in KCL22-R reduces either STAT3 activation or cell viability after IMA exposure. Therefore, our data suggest that SHP-1 plays an important role in BCR-ABL–independent IMA resistance modulating the activation signals that SHP-2 receives from both BCR/ABL and membrane receptor tyrosine kinases. The role of SHP-1 as a determinant of IMA sensitivity has been further confirmed in 60 consecutive untreated patients with chronic myelogenous leukemia, whose SHP-1 mRNA levels were significantly lower in case of IMA treatment failure (P 〈 .0001). In conclusion, we suggest that SHP-1 could be a new biologic indicator at baseline of IMA sensitivity in patients with chronic myelogenous leukemia.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2011
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    In: Blood, American Society of Hematology, Vol. 96, No. 3 ( 2000-08-01), p. 1070-1079
    Abstract: Targeting the tyrosine kinase activity of Bcr-Abl with STI571 is an attractive therapeutic strategy in chronic myelogenous leukemia (CML). A few CML cell lines and primary progenitors are, however, resistant to this compound. We investigated the mechanism of this resistance in clones of the murine BaF/3 cells transfected with BCR-ABL and in 4 human cell lines from which sensitive (s) and resistant (r) clones were generated by various methods. Although the resistant cells were able to survive in the presence of STI571, their proliferation was approximately 30% lower than that of their sensitive counterparts in the absence of the compound. The concentration of STI571 needed for a 50% reduction in viable cells after a 3-day exposure was on average 10 times higher in the resistant (2-3 μmol/L) than in the sensitive (0.2-0.25 μmol/L) clones. The mechanism of resistance to STI571 varied among the cell lines. Thus, in Baf/BCR-ABL-r, LAMA84-r, and AR230-r, there was up-regulation of the Bcr-Abl protein associated with amplification of the BCR-ABL gene. In K562-r, there was no Bcr-Abl overexpression, but the IC50 for the inhibition of Bcr-Abl autophosphorylation was increased in the resistant clones. Sequencing of the Abl kinase domain revealed no mutations. The multidrug resistance P-glycoprotein (Pgp) was overexpressed in LAMA84-r, indicating that at least 2 mechanisms of resistance operate in this cell line. KCL22-r showed neither Bcr-Abl up-regulation nor a higher threshold for tyrosine kinase inhibition by STI571. We conclude that BCR-ABL–positive cells can evade the inhibitory effect of STI571 by different mechanisms, such as Bcr-Abl overexpression, reduced intake mediated by Pgp, and, possibly, acquisition of compensatory mutations in genes other than BCR-ABL.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2000
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    In: Blood, American Society of Hematology, Vol. 112, No. 11 ( 2008-11-16), p. 1086-1086
    Abstract: After 5 years of imatinib treatment, only a minority of newly diagnosed chronic myeloid leukemia chronic phase (CML-CP) patients achieve complete molecular response. Imatinib has antiproliferative effects, but may not be able to eradicate CML-stem cells. Preclinical studies of imatinib suggested that sustained BCR-ABL kinase inhibition was required to block proliferation and induce apoptosis in CML cells. This formed the rationale for treatment regimens that maintain continuous kinase inhibition. Clinical studies with dasatinib suggested that daily dosing achieves equivalent response to twice daily even though ABL kinase inhibition only persists for 4–6 hours. We have demonstrated that 30 minutes of exposure to 100 nM dasatinib or 30 μ M imatinib (equipotent) inhibit p-Crkl (surrogate marker of Bcr-Abl kinase activity) by 80 to 90% in Bcr-Abl +ve cell lines and CML-CD34+ cells (n=8). We then sought to compare antiproliferative and pro-apoptotic effects of short term (ST; cells were cultured with dasatinib/imatinib for 30 minutes and after thorough wash, were recultured without dasatinib/imatinib for 72 hours) and continuous (CT, cells were cultured with drugs continuously) dasatinib or imatinib in BCRABL +ve cell lines (K562, Meg 01) and CD34+ cells of CML-CP patients. Although Bcr- Abl kinase reactivated within 30 minutes of drug removal, ST 100 nM dasatinib (D100ST) or 30μ M of imatinib (IM30ST) induced apoptosis (~80%) and blocked cell proliferation equivalent to continuous dasatinib (10 nM; D10CT) or imatinib (2μ M, IM2CT) in Bcr-Abl +ve cell lines. The kinetics of cell death and caspase-3 activation over 72 hours of culture were similar in D100ST and D10CT. In the presence of 6-growth factors (GFs; IL-3, IL- 6, G-CSF, SCF, TPO, Flt-3) D100ST and IM30ST reduced cell viability and CFU-GM colonies of CML-CD34+ cells by only 25 to 30% of no drug control. Moreover in the presence of GFs, 30 to 40% CD34+ve cells were viable and retained CFU-GM potential in spite of continuous dasatinib 100 nM (D100CT) or 30 μ M of imatinib (IM30CT). However, in the absence of GFs, D100ST and IM30ST reduced viability by 60 to 70%, and CFU-GM by 95% of control (with GFs, no TKI control; Fig 1). Figure 1: Survival of CFU-GM according to growth factor and dasatinib exposure: Figure 1:. Survival of CFU-GM according to growth factor and dasatinib exposure: Conclusion: Short term intense inhibition of BCR-ABL kinase activity triggers apoptosis in CML cell lines, which demonstrate their Bcr-Abl oncogene dependence. However, in spite of & gt;80% kinase inhibition, D100ST and D100CT did not eliminate the majority of CML-CD34+ cells in the presence of GFs. In the absence of GFs, D100ST and IM30ST were able to inhibit cell proliferation, induce cell death and eliminate 95% of CFU-GM. This data suggests that oncogene dependence of CML CD34+ cells can be overcome by cytokines. Unlike CML cell lines where transient intense kinase inhibition leads to cell death, primary CML cells are only sensitive to this short term kinase inhibition in the absence of cytokines. Strategies that block cytokine pathways in combination with Bcr-Abl kinase inhibition may eliminate leukemic stem cells in-vivo even if only applied intermittently. CFU-GM colonies expressed as % of control. CML-CD34+ cells (n=3) were cultured with dasatinib in the presence (With GFs) or absence (No GFs) of 6-growth factors (GF) and CFU-GM colonies were plated on D3, using Methocult 4230 (Invitrogen) along with growth factors in all cases. Colonies were read after 14 days. In each patient values were normalised to cells cultured with GFs and no dasatinib. Short term (ST) and continuous (CT), Dasatinib 10 nM (D10), 100 nM (D100).
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2008
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Online Resource
    Online Resource
    American Society of Hematology ; 2005
    In:  Blood Vol. 106, No. 11 ( 2005-11-16), p. 2991-2991
    In: Blood, American Society of Hematology, Vol. 106, No. 11 ( 2005-11-16), p. 2991-2991
    Abstract: Transformation by the Bcr-Abl oncoprotein of CML is mediated by the activation of a variety of signalling pathways, leading to transcriptional regulation of genes conferring the malignant phenotype of increased proliferation, altered adhesion and inhibition of apoptosis. We previously reported that expression of the BACH2 gene is downregulated by Bcr-Abl. Bach2 is a B-lymphoid specific transcription factor, which regulates somatic hypermutation and class switch recombination of Ig genes. It is also a pro-apoptotic factor, coupling oxidative stress to transcription repression. It is possible that in an environment of increased genomic instability, Bcr-Abl transformed cells may repress pro-apoptotic signals by suppressing BACH2 transcription. To determine the direct association between Bcr-Abl and decreased BACH2 transcription, we infected human B-lymphoid cells with a retroviral vector expressing both p210Bcr-Abl and eGFP genes. Infected cells were treated with imatinib, an Abl tyrosine kinase inhibitor, prior to quantification of BACH2 transcripts by Real Time RT/PCR. Ectopic expression of BCR-ABL significantly decreased BACH2 mRNA levels, and this effect was completely abolished by imatinib. To investigate whether this regulation was exerted at the transcriptional level, we identified the BACH2 transcription initiation site (TIS), and then cloned and characterised a 3.9 Kb genomic DNA fragment including the BACH2 promoter region. By generating luciferase reporter constructs of various lengths of the BACH2 promoter we found that a region of 725 bp upstream the TIS conferred maximum promoter activity in human B-lymphoid cells. The effect of Bcr-Abl on promoter activity was demonstrated by co-transfection of the reporter and p210Bcr-Abl constructs. BACH2-promoter activity was reduced up to 60% in the presence of Bcr-Abl. Furthermore, when co-transfected cells were incubated with different concentrations of imatinib, the Bcr-Abl-mediated promoter repression was abrogated in a dose dependent manner, confirming the dependence of the effect on the tyrosine kinase activity of the oncoprotein. In support of these data, no effect on promoter activity was seen when the BACH2 promoter was co-transfected with a kinase-dead BCR-ABL construct. Moreover, treatment with imatinib of the BCR-ABL+ cell line BV173 transfected with the reporter induced a nearly 2-fold upregulation in its activity. Bioinformatics inspection of the promoter sequence revealed potential sites for the Pax5 B-cell differentiation factor and the Foxo3a transcription factor, a regulator of pro-apoptotic genes. In co-transfection experiments of either factor with the BACH2 promoter, both demonstrated a significant inducing effect on its activity. Gel shift and chromatin immunoprecipitation showed direct binding of Pax5 within the BACH2 promoter in vitro and in vivo. Moreover, Western analysis showed elevated Pax5 levels in BCR-ABL+ cell lines after imatinib treatment, indicating that inhibition of Bach2 expression by Bcr-Abl is mediated at least in part by Pax5. As to Foxo3a, it has been reported to be constitutively phosphorylated and inactivated in BCR-ABL+ cells, processes which prevent its translocation to the cell nucleus. Altogether, our data suggest that Bcr-Abl transcriptional repression of Bach2 via Pax5 could lead to a differentiation arrest in transformed B-cells, and that Foxo3a may induce imatinib-mediated apoptosis through up-regulation of the Bach2 apoptotic function.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2005
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Online Resource
    Online Resource
    American Society of Hematology ; 2003
    In:  Blood Vol. 101, No. 11 ( 2003-06-01), p. 4231-4231
    In: Blood, American Society of Hematology, Vol. 101, No. 11 ( 2003-06-01), p. 4231-4231
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2003
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages