ABCG2 C.421C>A Is Associated with Higher Trough Imatinib Plasma Levels in Patients with Chronic Myeloid Leukemia.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 110-110
Author(s):  
Naoto Takahashi ◽  
Masatomo Miura ◽  
Stuart A Scott ◽  
Kenichi Sawada
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Plasma Levels ◽  
Myeloid Leukemia ◽  
Drug Transport ◽  
Conflicts Of Interest ◽  
Nucleotide Polymorphisms ◽  
Wild Type ◽  
Large Patient

Abstract Abstract 110 [Background] Despite the excellent efficacy of imatinib for the treatment of chronic myeloid leukemia (CML), trough imatinib plasma levels can vary widely among patients. This may be due, in part, to inter-individual variation in imatinib metabolism and drug transport efficacy. To investigate the role of genetic variation in the pharmacokinetics of imatinib, we analyzed common single nucleotide polymorphisms within important imatinib pathway genes including ABCG2 (BCRP), ABCB1 (MDR1), ABCC2 (MRP2), CYP3A5, and SLC22A1 (OCT1) in 67 CML patients treated with imatinib. In addition, trough imatinib plasma levels were determined using high-performance liquid chromatography-tandem mass spectrometry. [Results] Distinct imatinib pharmacokinetics were identified in association with ABCG2 c.421C>A (p.Q141K; rs2231142) genotype. Specifically, the presence of the variant c.421A allele was significantly (p=0.024) associated with higher imatinib concentrations [median Cmin/Dose 2.70 (range: 1.50-8.30) ng/ml/mg; n=25] compared to patients with the wild-type ABCG2 (c.421C/C) genotype [median Cmin/Dose 2.27 (range: 0.37-5.30) ng/ml/mg; n=42]. ABCG2 is an efflux transporter for many xenobiotics, including imatinib, and is expressed at high levels in the human liver. Previous studies indicate that c.421A causes a 40% reduction in imatinib transport in vitro when compared to the wild-type genotype. Our data suggest that CML patients with ABCG2 c.421A allele may have deficient ABCG2 activity in vivo, resulting in reduced hepatic excretion of imatinib. Of note, although less common among Africans and individuals of European decent, the ABCG2 c.421C>A allele occurs at a high frequency in the Japanese (0.311) and Han Chinese (0.289) populations. [Conclusion] The association of ABCG2 c.421C>A with imatinib pharmacokinetics may explain why some Japanese CML patients administered less than 400 mg/day of imatinib have clinically sufficient trough imatinib plasma levels. Prospective studies are warranted to confirm the association between ABCG2 genotype and imatinib pharmacokinetics in large patient populations. Disclosures: No relevant conflicts of interest to declare.

Quantitative Phosphoproteomics Identified a New Syk-Lyn-Axl Signalling Pathway Involved In Resistance to Nilotinib In Chronic Myeloid Leukemia Cells.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3376-3376
Author(s):  
Romain Gioia ◽  
Cedric Leroy ◽  
Claire Drullion ◽  
Valérie Lagarde ◽  
Serge Roche ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Myeloid Leukemia ◽  
Conflicts Of Interest ◽  
Critical Role ◽  
Dependent Manner ◽  
Stable Isotope Labelling ◽  
Resistant Cells

Abstract Abstract 3376 Nilotinib has been developed to overcome resistance to imatinib, the first line treatment of chronic myeloid leukemia (CML). To anticipate resistance to nilotinib, we generate nilotinib resistant CML cell lines in vitro to characterize mechanisms and signaling pathways that may contribute to resistance. Among the different mechanisms of resistance identified, the overexpression of the Src-kinase Lyn was involved in resistance both in vitro, in a K562 cell line (K562-rn), and in vivo, in nilotinib-resistant CML patients. To characterize how Lyn mediates resistance, we performed a phosphoproteomic study using SILAC (Stable Isotope Labelling with Amino acid in Cell culture). Quantification and identification of phosphotyrosine proteins in the nilotinib resistant cells point out two tyrosine kinases, the spleen tyrosine kinase Syk and the UFO receptor Axl. The two tyrosine kinase Syk and Axl interact with Lyn as seen by coimmunopreciptation. Syk is phosphorylated on tyrosine 323 and 525/526 in Lyn dependent manner in nilotinib resistant cells. The inhibition of Syk tyrosine kinase by R406 or BAY31-6606 restores sensitivity to nilotinib in K562-rn cells. In parallel, the inhibition of Syk expression by ShRNA in K562-rn cells abolishes Lyn and Axl phosphorylation and then interaction between Lyn and Axl leading to a full restoration of nilotinib efficacy. In the opposite, the coexpression of Lyn and Syk in nilotinib sensitive K562 cells induced resistance to nilotinib whereas a Syk kinase dead mutant did not. These results highlight for the first time the critical role of Syk in resistance to tyrosine kinase inhibitors in CML disease emphasizing the therapeutic targeting of this tyrosine kinase. Moreover, Axl, which is already a target in solid tumor, will be also an interesting pathway to target in CML. Disclosures: No relevant conflicts of interest to declare.

siRNA/lipopolymer nanoparticles to arrest growth of chronic myeloid leukemia cells in vitro and in vivo

2018 ◽  
Vol 130 ◽  
pp. 66-70 ◽  
Author(s):  
Juliana Valencia-Serna ◽  
Hamidreza M. Aliabadi ◽  
Adam Manfrin ◽  
Mahsa Mohseni ◽  
Xiaoyan Jiang ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Leukemia Cells ◽  
Arrest Growth

Thymic Immunosuppressive Pentapeptide (TIPP) Showed Anticancer Activity in Breast Cancer and Chronic Myeloid Leukemia Both In Vitro and In Vivo

2021 ◽  
Vol 28 ◽  
Author(s):  
Muhammad Ijaz ◽  
Muhammad Shahbaz ◽  
Wenjie Jiang ◽  
Yikang Shi ◽  
Xiuli Guo ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Chronic Myeloid Leukemia ◽  
Anticancer Activity ◽  
Myeloid Leukemia ◽  
Map Kinases ◽  
Inflammatory Responses ◽  
Tumor Xenograft ◽  
Immunohistochemistry Analysis

Aim: Being the common cause and major burden of deaths globally, timely management of cancer is crucial. Background: Thymic immunosuppressive pentapeptide (TIPP) is a novel pentapeptide originally obtained from calf thymic immunosuppressive extract. Previously, TIPP has been proved to suppress the allergic and inflammatory responses in allergic mice via blocking MAP kinases/NF-κB signaling pathways. Objective: In this study, in vitro anticancer activity of TIPP was tested on two different types of cancers using MCF-7 and K562 cell lines. Methods: Tumor xenograft models for breast cancer and chronic myeloid leukemia were designed. In vivo anticancer activity of TIPP was investigated on both cancer types. The liver and tumor tissues of the mice were preserved for immunohistochemistry analysis. Results: In vitro anticancer activity of TIPP showed significant inhibition on cell viability of both breast cancer and chronic myeloid leukemia. In vivo anticancer effect of TIPP in both types of cancer models further proved the potent anticancer nature of TIPP. Immunohistochemistry analysis assured that TIPP is a safe drug for normal organs such as the liver. Conclusion: Our present study revealed that TIPP is a potent anticancer drug and an important treatment option for various diseases. Further work is needed to test the flexible and proficient activity of the novel peptide.

scholarly journals Detection of breakpoint cluster region- negative and nonclonal hematopoiesis in vitro and in vivo after transplantation of cells selected in cultures of chronic myeloid leukemia marrow

Blood ◽  
1990 ◽  
Vol 76 (11) ◽  
pp. 2404-2410 ◽  
Author(s):  
AG Turhan ◽  
RK Humphries ◽  
CJ Eaves ◽  
MJ Barnett ◽  
GL Phillips ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Hematopoietic Cells ◽  
Breakpoint Cluster Region ◽  
Cluster Region ◽  
Differentiated Cells ◽  
The One

Abstract Philadelphia (Ph1) chromosome-positive clonogenic progenitors usually disappear within 4 to 6 weeks in long-term cultures established from the marrow of patients with chronic myeloid leukemia (CML). In contrast, coexisting chromosomally normal hematopoietic cells are relatively well maintained. Thus, even though normal cells are initially undetectable, they may become the predominant population. Recently, we have begun to explore the potential of such cultures as a strategy for preparing CML marrow for autografting, and based on cytogenetic studies of the differential kinetics of Ph1-positive and Ph1-negative clonogenic cells, have chosen a 10-day period in culture to obtain maximal numbers of selectively enriched normal stem cells. Here we present the results of molecular analyses of the cells regenerated in vivo for the initial three CML patients to be treated using this approach by comparison with the differentiated cells generated by continued maintenance of an aliquot of the autograft in vitro (using a slightly modified culture feeding procedure to enhance the production and release of cells into the nonadherent fraction after 4 weeks) for the one patient whose genotype made molecular analysis of clonality status also possible. These analyses showed that cells with a rearranged breakpoint cluster region (BCR) gene were not detectable by Southern blotting in either in vitro or in vivo populations of mature cells that might be assumed to represent the progeny of primitive cells present at the end of the initial 10 days in culture. Production of BCR- negative cells was also shown to be temporally correlated with the appearance of nonclonal hematopoietic cells both in culture and in vivo. These findings provide support for the view that prolonged maintenance of CML marrow cells in long-term culture may allow molecular characterization of both the BCR-genotype and clonality status of cells with in vivo regenerative potential.

α1-Acid glycoprotein expressed in the plasma of chronic myeloid leukemia patients does not mediate significant in vitro resistance to STI571

Blood ◽  
2002 ◽  
Vol 99 (2) ◽  
pp. 713-715 ◽  
Author(s):  
Heather G. Jørgensen ◽  
Moira A. Elliott ◽  
Elaine K. Allan ◽  
Christine E. Carr ◽  
Tessa L. Holyoake ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Plasma Proteins ◽  
Myeloid Leukemia ◽  
Philadelphia Chromosome ◽  
Drug Efficacy ◽  
Acid Glycoprotein ◽  
Proliferation In Vitro ◽  
Normal Controls

Abstract Despite the efficacy of STI571 (Glivec, Novartis, Basle, Switzerland) in treating chronic myeloid leukemia (CML), drug resistance has already been noted both in vitro and in vivo. As plasma proteins, including alpha-1-acid glycoprotein (AGP), may reduce drug efficacy through binding, AGP was investigated for its ability to interact with STI571.  At all stages of CML, AGP plasma level was significantly higher than in normal controls (P < .05). The glycoprotein was purified from normal plasma and individual chronic myeloid leukemia (CML) patients' plasma by low-pressure chromatography. The influence of α1-acid glycoprotein (AGP), in the presence of STI571, on the proliferation of Philadelphia chromosome–positive (Ph+) cells was examined. Normal AGP, even at supraphysiological concentrations, did not block the effect of STI571 on K562-cell proliferation in vitro. Moreover, CML-derived AGP failed to block the effect of STI571 on Ph+ cells in vitro. Thus, these in vitro findings suggest that AGP will not abrogate the antileukemic activity of STI571.

Selective elimination of leukemic CD34+ progenitor cells by cytotoxic T lymphocytes specific for WT1

Blood ◽  
2000 ◽  
Vol 95 (7) ◽  
pp. 2198-2203 ◽  
Author(s):  
Liquan Gao ◽  
Ilaria Bellantuono ◽  
Annika Elsässer ◽  
Stephen B. Marley ◽  
Myrtle Y. Gordon ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Chronic Myeloid Leukemia ◽  
T Lymphocytes ◽  
Progenitor Cells ◽  
Cytotoxic T Lymphocytes ◽  
Colony Formation ◽  
Myeloid Leukemia ◽  
Leukemia Cell

Abstract Hematologic malignancies such as acute and chronic myeloid leukemia are characterized by the malignant transformation of immature CD34+ progenitor cells. Transformation is associated with elevated expression of the Wilm's tumor gene encoded transcription factor (WT1). Here we demonstrate that WT1 can serve as a target for cytotoxic T lymphocytes (CTL) with exquisite specificity for leukemic progenitor cells. HLA-A0201– restricted CTL specific for WT1 kill leukemia cell lines and inhibit colony formation by transformed CD34+ progenitor cells isolated from patients with chronic myeloid leukemia (CML), whereas colony formation by normal CD34+ progenitor cells is unaffected. Thus, the tissue-specific transcription factor WT1 is an ideal target for CTL-mediated purging of leukemic progenitor cells in vitro and for antigen-specific therapy of leukemia and other WT1-expressing malignancies in vivo.

Functional Alterations of NKT Cells in Chronic Myeloid Leukemia Patients Can Be Reversed by Imatinib Mesylate In Vitro.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2128-2128
Author(s):  
Alexis Rossignol ◽  
Anne Barra ◽  
Francois Guilhot ◽  
Ali G. Turhan ◽  
Jean-Marc Gombert
Keyword(s):  
T Cell ◽  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Proliferative Response ◽  
Nkt Cells ◽  
Nkt Cell ◽  
Healthy Donors ◽  
Cytogenetic Remission

Abstract Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by the presence of the pathognomonic Philadelphia chromosome and the chimeric BCR-ABL oncoprotein with deregulated tyrosine kinase activity. It has been shown previously that T cell immunity contributes to the control of CML, and several arguments suggest an implication of NKT cells in this anti-tumoral immunity. We thus compared frequency, phenotype and functions of blood NKT cells (defined by the CD1d tetramer+ Vα24+ staining) in healthy subjects and patients with CML. Three groups of patients were studied, including Patients in chronic phase (CP) (either at diagnosis or unresponsive to treatment) patients in major/complete cytogenetic remission induced by interferon-alpha (IFN-α) or patients in major/complete cytogenetic remission induced by imatinib mesylate (IM, a specific inhibitor of the BCR-ABL tyrosine kinase). Our results showed that blood NKT cells frequency was not significantly different between healthy donors (n = 17), CP patients (n = 14) and IM-treated patients (n = 16) (0.062 % versus 0.079 % versus 0.041 % respectively). On the other hand, this frequency defined as above was found to be dramatically decreased in patients in complete remission after IFN-α therapy ( 0.01 %, n = 15 patients). We have then analyzed from the phenotypic point of view NKT cells from these three groups. This ex vivo phenotypic study showed that NKT phenotype (expression of CCR7 and CD161) was clearly modified in the IFN-treated group as compared to IM-treated or CP patients and healthy donors, with a clear enrichment in CD161-CCR7+ NKT cells (49% versus 26%, 22% and18% respectively). This CD161-CCR7+ phenotype has been described as the central memory T cell phenotype, with increased lymph-node homing and antigen-presenting cell-stimulating capacities. We have then performed functional studies of NKT cells measuring their proliferative response to α-galactosylceramide (αGC) as a specific triggering antigen. NKT proliferative response to α-GC was abolished in CP patients (2-fold expansion versus 83-fold in healthy donors). This functional impairment was found to be restored in patients treated with IM and in patients treated with IFN-α (106-fold and 20-fold expansion respectively), although this latter group had a strongly depleted NKT compartment. More interestingly, the incubation of CP CML cells in the presence of IM (0.5 and 1 micromolar, n = 5) led to the partial restoration of the NKT cell reactivity to α-GC (29-fold expansion versus α-GC alone). Thus, our results suggest that IFN-α therapy leads to the generation of "central memory-like phenotype" NKT cells, which could play an important role in the long-term remissions observed in these patients. Moreover, our results strongly suggest that IM is able to partially restore the antigenic-response of CML NKT cells in vitro and in vivo, suggesting a role of BCR-ABL in the anergic state of these cells as this was observed at diagnosis. The IM-induced restoration of NKT cell proliferation defect in CP patients suggest that the antileukemic effect of IM could also be partially due to this action in vivo. Cellular mechanisms involved in this phenomenon are currently under study.

In Vitro Sensitivity to Tyrosine Kinase Inhibitors Is One of Possible Predictive Parameters for Therapy Switch In Patients with Chronic Myeloid Leukemia

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2747-2747
Author(s):  
Marketa Zackova ◽  
Tereza Lopotova ◽  
Zuzana Ondrackova ◽  
Hana Klamova ◽  
Jana Moravcova
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Kinase Inhibitors ◽  
Transcript Level ◽  
Molecular Response ◽  
Newly Diagnosed ◽  
Therapy Switch

Abstract Abstract 2747 Backround: Tyrosine kinase inhibitors (TKI) are very effective in chronic myeloid leukemia (CML) suppression, however, the problem with development of resistance in some patients exists. It is necessary to find optimal methods for therapy response prediction and for detection of resistance. Many studies on the resistance to imatinib therapy were performed on cell lines or model systems. However, these systems are not fully consistent with CML situation in vivo. Sensitivity to imatinib and its predictivity to molecular response in patients with de novo CML were tested in vitro on patients′ leukocytes by White et al. [Blood 2005; 106: 2520]. They found that IC50 values could be predictive mainly in patients with low Sokal score. Aims: To optimize in vitro method for evaluation of patients′ sensitivity to various TKIs and to test its predictivity for molecular response in therapy and/or after therapy change. Methods: The sensitivity to TKIs: imatinib, nilotinib and dasatinib were studied on leukocytes isolated from CML patients at diagnosis and various responses to treatment. Cell lines were used as controls. Isolated leukocytes/cell lines were cultivated with/without TKIs. Optimization of cultivation was performed on cell lines (ML-2, K562, CML-T2, JURL-MK1) and on leukocytes from CML newly diagnosed patients (15) and healthy donors (6). Various incubation times (4, 24, 48 and 72h) were tested. Concentrations of TKI were used in values near to physiological levels: 2 –3 concentrations for each inhibitor (1uM, 10uM imatinib, 0,5uM and 2uM nilotinib and 1nM, 10nM and 100nM dasatinib). In given time-points the cells were harvested and lysed for protein and mRNA analyses. Sensitivity to TKIs was tested by BCR-ABL kinase inhibition – via Crkl phosphorylation (western blots) and also by WT1 transcript level kinetics [Cilloni et al, Cancer 2004; 101: 979]. Quality of cultivation was tested by apoptosis level (RNA degradation, Annexin staining – Agilent Bioanalyzer 2100). Results: We found 48 h to be the optimal time for in vitro cultivation. This time was long enough to see TKIs dependent changes on protein as well as mRNA level. At this time the intensity of apoptosis was relatively low and did not influence results. The predictive ability of cultivation with TKIs was tested on patients at diagnosis (15), with optimal (5) and suboptimal response (5) and patient with therapy failure (13). The disease state of all patients was further monitored in range from 6 to 21 months (median 12 months) after cultivation. Mostly all of newly diagnosed patients were in vitro sensitive to all three TKIs, 10 of them achieved MMR (median 7 months, range 5 – 16) on imatinib. In patients with resistance to imanitib therapy the good sensitivity to one of 2nd generation TKI on in vitro tests represented the good response to this inhibitor, 4 patients from 10 on dasatinib achieved MMR (within 4 months), the other responded to therapy with continual decrease of BCR-ABL transcript level. Thus, the cultivation test can help with the therapy switch. However, the prognosis of patients with additive chromosomal aberration was poor even if they were sensitive to TKIs in vitro. Only one of 3 patients with 8 trisomy sensitive to dasatinib in vitro achieved MMR at 4th month after starting of dasatinib. Two patients with T315I were not sensitive to any of TKIs in vitro and in vivo, as it was expected. We continue to follow up of all patients. In conclusion, the results from in vitro cultivations of patients′ leukocytes with TKIs can help with the choice of efficient inhibitor for individual patient′s therapy, however, it is necessary to take into consideration the results of cytogenetic analyses of patients and other factors influencing CML. Supported by MZOUHKT2005. Disclosures: No relevant conflicts of interest to declare.

BCR-ABL-Induced Transcriptional Repression of the Interferon Regulatory Factor 8 (IRF-8/ICSBP) Leads to Depletion of Plasmocytoid Dendritic Cells (PDC), Which May Contribute to Leukemogenesis in a Murine Model of Chronic Myeloid Leukemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 36-36 ◽  
Author(s):  
Sabrina Inselmann ◽  
Simone Liebler ◽  
Cornelia A Brendel ◽  
Steffen Koschmieder ◽  
Andreas Neubauer ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Cpg Odn ◽  
Toll Like Receptor ◽  
Rt Pcr ◽  
Healthy Donors ◽  
Functional Relevance

Abstract Abstract 36 Introduction: Chronic myeloid leukemia (CML) is caused by the BCR-ABL oncogene. CML patients lack expression of IRF-8 - an interferon-regulated transcription factor that has been shown to exert tumor suppressor functions. IRF-8 is also critical for the development of a rare dendritic cell population, so called plasmocytoid dendritic cells (PDC). PDC are quantitatively significantly reduced or absent in the peripheral blood of first diagnosis CML patients. PDC are also the major producers of IFN-alpha (IFNa) in man. IFNa is a cytokine that has significant therapeutic efficiency in the treatment of CML patients. We here wished to experimentally test, whether BCR-ABL expression and loss of IRF-8 may be causally linked to a reduction of PDC in murine CML and whether there could be any functional relevance for PDC loss in CML development or treatment. Methods: PDC counts were studied from peripheral blood samples of primary CML patients at diagnosis, at the time of remission or from healthy donors. PDC function was assessed in vitro by treatment of magnetic bead-enriched PDC with Toll-like receptor 9-specific oligos (ODN 2216) and subsequent assessment of the intracellular IFNa expression in stimulated PDC. A supposed link between BCR-ABL expression, IRF-8 repression and loss of PDC counts was studied in vivo using a murine CML transduction-transplantation model (C57/Bl6 mice, 7Gy sub-lethal irradiation for conditioning). Multiparameter flow cytometry and cell sorting were performed to analyze and enrich, BCR-ABL-positive (GFP+) hematopoietic subpopulations and PDC in order to then quantitate their IRF-8 and BCR-ABL transcript level by RT-PCR. In order to also test the functional relevance of PDC during CML leukemogenesis, CML mice were injected intravenously, weekly from day +5 after transplantation with in vitro generated PDC. Mice were simultaneously also s.c.-injected weekly with ODN 2216 to stimulate IFNα secretion in adoptively transferred PDC in vivo. Results: As previously reported, newly diagnosed CML patients displayed a significantly reduced PDC count when compared to healthy donors (p<0.001). Upon remission induction with imatinib, PDC counts restored partially, but to a much lesser extend in patients successfully treated with IFNa therapy. Importantly, albeit significantly reduced in number, BCR-ABL-positive first diagnosis CML PDC seem to be functionally intact: CML and healthy donor PDC produced comparable amounts of IFNa in response to Toll-like receptor 9 -specific CpG ODN 2216 stimulation. This suggested that BCR-ABL may compromise PDC function by quantitative rather than qualitative dysregulation. CML mice developed a fatal, BCR-ABL-positive myeloproliferation within 13 to 29 days with 88% penetrance. Compared to control mice (n=8), CML mice (n=14) showed a 7-fold and 3-fold reduction of the frequency of B220+mPDCA-1+ PDC in bone marrow and spleen, respectively. This was associated with a statistically significant (4-fold) suppression of IRF8 mRNA expression in sorted BCR-ABL(GFP)-positive PDC relative to BCR-ABL-negative PDC from the same mice (n=3) or from control transplantations (n=5). By RT-PCR, there was a trend also for lower IRF8 expression in CML progenitor cells (Lin− c-Kit+ Sca-1- GFP+), but not in the stem cell enriching population (Lin− c-Kit+ Sca-1+ GFP+). This implied that IRF8 expression is lost during BCR-ABL-induced leukemogenesis in more mature compartments, which supposedly include PDC precursors. Intriguingly, a once weekly adoptive transfer of in vitro generated (to > 30% enriched) PDC for three successive weeks combined with a once weekly subcutaneous injection of CpG ODN 2216 for three weeks was sufficient to almost double survival of CML mice. Conclusions: Using a murine model of CML, we provide first experimental evidence that BCR-ABL induced myeloproliferation is causally linked to a quantitative suppression of PDC, and that this is associated with a BCR-ABL-mediated suppression of IRF8 transcription. Since adoptively transferred PDC were capable of counteracting murine CML development, BCR-ABL may facilitate leukemogenesis in part by obstructing PDC maturation. PDC could thus be a novel immunological effector cell population that exerts and/or integrates anti-leukemic immune responses in CML. Disclosures: No relevant conflicts of interest to declare.

The Mechanisms of Synergistically Cytotoxicity Induced by Homoharringtonine and Aclarubicin in Acute Myeloid Leukemia Cells

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4313-4313
Author(s):  
Lei Wang ◽  
Jie Jin
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Conflicts Of Interest ◽  
Akt Pathway ◽  
Apparent Difference ◽  
Akt Inhibitor ◽  
Simultaneous Exposure ◽  
Acute Myeloid

Abstract Abstract 4313 Previous studies showed HAA regime [HHT (homoharringtonine), cytarabine and ACR (aclarubicin)] resulted in a high complete remission (CR) rate and a better overall survival (OS) rate in patients with primary acute myeloid leukemia. To confirm if a synergistically cytotoxicity was found in AML cells, we investigated the antitumor effect relationship of HHT and ACR against AML cells. Using in vitro system, we demonstrated that simultaneous exposure to HHT and ACR resulted in strong synergistic anti-proliferative effect and apoptosis inducing in AML cells. In vivo, combination of HHT and ACR may be result in a favorable survival in AML xenograft mice. The assay of microarray gene expressing profiling highlighted apparent difference in expression of PI3K gene and WNT3a gene between cells treated by HHT and cells exposure to ACR. Furthermore, decreased expression of PI3K110 and P-AKT protein were observed in AML cells treated with HHT for 3h while no significant change in the expression of two proteins was observed in 90nM of ACR-treated cells. Western Blot analysis also showed ACR could obviously inhibit WNT3a and β-catenin protein levels in AML cells after 3 hours exposure. Although HHT could not inhibit WNT3a protein, it also could apparently down-regulate expression of β-catenin in AML cells. Simultaneous decrease of PI3K signal and WNT3a signal was induced by the combination of HHT and ACR in AML cell lines and primary AML cells. To explore possible targets of synergistically cytotoxity induced by combined HHT/ACR, we silenced wnt3a expression by RNA interference. Then we found suppression of wnt3a expression could enhance the cytotoxity of HHT and AKT inhibitor. Moreover, combining ACR with AKT inhibitor resulted in a synergistically cytotoxic effect too. β-catenin is a shared molecular in both AKT pathway and WNT pathway. Up-regulating of β-catenin expression failed to reduce cell apoptosis induced by HHT plus ACR while partially decrease the growth inhibition rate caused by combining treatment. β-catenin is required for the self-renewal of AML-LSC. Our study also suggests that combining HHT and ACR may synergistically induce apoptosis in LSC-enriched cells. These results indicate that simultaneously inhibiting activity of PI3K/AKT pathway and WNT/β-catenin pathway is a possible mechanism of synergistically cytotoxity induced combinated HHT/ACR in AML cells. Disclosures: No relevant conflicts of interest to declare.

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