The Heat Shock Protein 32 (Hsp32)/HO-1-Targeting Drug SMA-ZnPP and the Triterpenoid CDDO-Me Exert Synergistic Growth-Inhibitory Effects on TKI-Resistant Leukemic Cells in Ph+ CML

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4414-4414
Author(s):  
Karoline V. Gleixner ◽  
Harald Herrmann ◽  
Katharina Blatt ◽  
Winfried F Pickl ◽  
Marina Konopleva ◽  
...  
Keyword(s):  
Heat Shock ◽  
Growth Inhibition ◽  
Synergistic Effects ◽  
K562 Cells ◽  
Leukemic Cells ◽  
Drug Resistant ◽  
Inhibitory Effects ◽  
Growth Inhibitory ◽  
Imatinib Resistant ◽  
Ic50 Values

Abstract Abstract 4414 Resistance against one or more tyrosine kinase inhibitors (TKI) prevents eradication of Ph+ chronic myeloid leukemia (CML). In many patients BCR/ABL1 mutations are detectable. We have recently identified two targeted drugs that exert major growth-inhibitory effects on drug-resistant CML cells, the triterpenoid CDDO-Me (Bardoxolone-methyl, REATA Pharma) that blocks several signalling molecules including mTOR, Akt, and STAT3, and upregulates expression of heat shock protein 32 (Hsp32 = heme oxygenase 1, HO-1), and styrene-maleic acid-copolymer micelle-encapsulated ZnPP (SMA-ZnPP), a water-soluble inhibitor of Hsp32/HO-1. In the current project, we asked whether CDDO-Me exerts inhibitory effects on growth of TKI-resistant CML cells and whether the combination of CDDO-Me and SMA-ZnPP would produce synergistic effects in drug-resistant CML cells. As determined by 3H-thymidine incorporation, CDDO-Me was found to inhibit the proliferation of imatinib-responsive and imatinib-resistant K562, imatinib-resistant KCL-22, KU812, and Ba/F3 cells transfected with various TKI-resistant mutants of BCR/ABL1 (T315I, E255K, Y253F, H396P). In each case, IC50 values <1 μM were obtained without major differences between imatinib-responsive and imatinib-resistant cells. Growth-inhibition was accompanied by apoptosis as assessed by combined AnnexinV/PI staining as well as by an increase in expression of HO-1 in KU812 and KCL-22 cells. CDDO-Me was also found to inhibit proliferation of leukemic cells in all patients with TKI-resistant CML (n=4), with IC50 values ranging between <0.1 and 0.5 μM. No differences in IC50 values were observed between treatment-naïve and TKI-resistant cells. Next, we applied the combination CDDO-Me+SMA-ZnPP and found that this combination acts highly synergistically on imatinib-responsive and imatinib-resistant K562 cells as well as primary CML cells isolated from imatinib-naïve CML patients (n=2) or from patients with imatinib-resistant CML (n=2), including one patient in whom BCR/ABL1 T315I was detected. We also examined whether CDDO-Me would exert synergistic effects on CML cells when combined with BCR/ABL1 TKI. In these experiments, we applied the combinations CDDO-Me+dasatinib and CDDO-Me+nilotinib on K562 cells. Both combinations were found to synergistically induce growth inhibition. In conclusion, CDDO-Me inhibits the proliferation of imatinib-resistant BCR/ABL1+ cells, including primary CML cells isolated from untreated patients and cells derived from patients with TKI-resistant CML carrying the BCR/ABL1 mutant T315I. Our data also show that CDDO-Me + SMA-ZnPP and CDDO-Me + BCR/ABL1 TKI synergize in producing growth inhibition in CML cells. Whether these drug combinations also produce synergistic effects in vivo in patients with TKI-resistant CML remains to be evaluated. Disclosures: Valent: Novartis: Consultancy, Honoraria, Research Funding.

Nilotinib and Dasatinib Produce Synergistic Growth-Inhibitory Effects In Imatinib-Resistant CML Cells, Including Subclones Bearing the Multi-Resistant BCR/ABL Mutant T315I

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2280-2280
Author(s):  
Karoline V. Gleixner ◽  
Harald Herrmann ◽  
Irina Sadovnik ◽  
Karina Schuch ◽  
Winfried F Pickl ◽  
...  
Keyword(s):  
Stem Cells ◽  
Research Funding ◽  
Synergistic Effects ◽  
Chronic Phase ◽  
Leukemic Cells ◽  
Inhibitory Effects ◽  
Blast Phase ◽  
Drug Concentrations ◽  
Growth Inhibitory ◽  
Imatinib Resistant

Abstract Abstract 2280 In most patients with chronic myeloid leukemia (CML), complete cytogenetic remission can be achieved with the BCR/ABL tyrosine kinase inhibitor (TKI) imatinib. However, not all patients are long-term responders. A major cause of acquired resistance against imatinib is the development of BCR/ABL mutations in subclones. In most of these patients, a second generation TKI is prescribed. However, the T315I mutant of BCR/ABL introduces resistance against most TKI, including nilotinib and dasatinib. One approach to overcome drug resistance in BCR/ABL T315I+ CML cells may be to apply drug combinations. Recent data suggest that the mechanisms through which dasatinib and nilotinib act on BCR/ABL differ from each other and that both drugs act on multiple additional targets in CML cells. Here, we show that dasatinib and nilotinib cooperate with each other in producing growth inhibition in imatinib-sensitive and imatinib-resistant CML cells, including subclones bearing BCR/ABL T315I. The drug combination was tested on leukemic cells obtained from 9 patients with chronic phase (CP) CML and 3 with blast phase (PB) of CML. Samples were assessed from 4 patients at the time of diagnosis, and against cells from 8 patients (CP, n=5; BP, n=3) who had developed resistance against one or more BCR/ABL TKI. In all 3 patients in PB, the T315I mutant was detectable. As expected, nilotinib and dasatinib failed to inhibit proliferation of cells harbouring BCR/ABL T315I when applied as single agents. However, the combination xnilotinib+dasatinibx produced synergistic effects in most samples, including primary CML cells and Ba/F3 cells harbouring BCR/ABL T315I. Interestingly, in all 3 patients with BP (BCR/ABL T315I+), strong cooperative or even synergistic growth-inhibitory effects were observed in primary CML cells, resulting in substantial anti-leukemic effects seen at reasonable (pharmacologic) drug concentrations (< 1 μ M) (figure). Based on these results, we treated one patient with TKI-resistant CML in hematologic relapse in whom 2 BCR/ABL mutant-bearing subclones, one clinically resistant against nilotinib (F359V) and one clinically resistant against dasatinib (F317L) had been detected, with a combination of nilotinb (800 mg p.o. daily) and dasatinib (50 mg/day p.o., days 1–5 every third week). A transient hematologic response was obtained in this patient, and except for mild bone pain, no side effects were recorded. Moreover, we were able to show that during treatment with xnilotinib+dasatinibx, the number of CD34+/CD38-/CD33+ CML stem cells decreased from clearly measurable levels (0.005%) to nearly undetectable levels (0.0002%). Finally, ex vivo analyses of leukemic blood cells confirmed, that the combination xnilotinib+dasatinibx produced strong cooperative growth-inhibitory effects in both disease-components, i.e. the F359V-bearing subclone and the F317L-bearing subclone. In summary, our data show that the combination of dasatinib and nilotinib can override acquired TKI resistance in CML, and can suppress growth of various imatinib-resistant subclones including cells that bear BCR/ABL T315I or other BCR/ABL mutants. Whether this combination can suppress imatinib-resistant subclones in CML for prolonged time periods or even can eradicate neoplastic stem cells remains in CML patients to be determined. Synergistic effects of nilotinib and dasatinib on primary leukemic cells obtained from a patient with a BCR/ABL T315I+ blast phase of CML Disclosures: Valent: Novartis: Research Funding; Bristol-Myers Squibb: Research Funding.

The Heme Oxygenase-1-Targeting Compound PEG-ZnPP Inhibits Growth of Imatinib-Resistant BCR/ABL-Transformed Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1986-1986 ◽  
Author(s):  
Matthias Mayerhofer ◽  
Karl J. Aichberger ◽  
Stefan Florian ◽  
Maria-Theresa Krauth ◽  
Sophia Derdak ◽  
...  
Keyword(s):  
Heme Oxygenase ◽  
Kinase Inhibitor ◽  
K562 Cells ◽  
Pi3 Kinase ◽  
Leukemic Cells ◽  
Heme Oxygenase 1 ◽  
Zinc Protoporphyrin ◽  
Inhibitory Effects ◽  
Growth Inhibitory ◽  
Imatinib Resistant

Abstract Chronic myeloid leukemia (CML) is a myeloproliferative disease characterized by the BCR/ABL oncogene and an increased survival of leukemic cells. The BCR-ABL tyrosine kinase inhibitor imatinib has successfully been introduced as a treatment of CML. However, resistance after an intitial response is common in patients with advanced disease, and it is not yet clear if responses in early disease phases will be durable. Therefore, current studies focus on novel potential drug-targets in CML cells. We have recently identified heme oxygenase-1 (HO-1) as a novel BCR/ABL-dependent survival-molecule in primary CML cells. In this study, we analyzed signal transduction pathways underlying BCR/ABL-induced expression of HO-1 and evaluated the role of HO-1 as a potential new target of drug therapy. We found that the PI3-kinase inhibitor LY294002 and MEK inhibitor PD98059 downregulate expression of HO-1 in CML cells. In addition, constitutively active Ras- and Akt -mutants were found to promote expression of HO-1 in Ba/F3 cells, further supporting the involvement of the PI3-kinase/Akt as well as the MAPK pathway in regulating HO-1 expression. To establish a role for HO-1 in survival of CML cells, expression of HO-1 was silenced by siRNAs which resulted in apoptosis of K562 cells. Next, HO-1 was targeted in CML cells by pegylated zinc protoporphyrin (PEG-ZnPP), a competitive inhibitor of HO-1. Exposure to PEG-ZnPP resulted in growth inhibition and induction of apoptosis in primary CML cells as well as in the CML-derived cell lines K562 and KU812 with IC50 values ranging between 1–10 μM. The growth-inhibitory effects of PEG-ZnPP were not only observed in CML cells responsive to imatinib, but also in imatinib-resistant K562 cells and Ba/F3 cells expressing various imatinib-resistant mutants of BCR/ABL (T315I, E255K, M351T, Y253F, Q252H, H396P). Moreover, imatinib and PEG-ZnPP were found to exert synergistic growth inhibitory effects on imatinib-resistant leukemic cells. Together, these data suggest that HO-1 represents a novel drug target in cells expressing BCR/ABL, including those with resistance to imatinib.

Effects of Bosutinib (SKI-606) in CML: Kinase Target Profile, Effects on BCR/ABL Mutants, and Synergism with Dasatinib in T315I+ Cells

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3195-3195
Author(s):  
Karoline Veronika Gleixner ◽  
Lily L Remsing Rix ◽  
Christian Baumgartner ◽  
Uwe Rix ◽  
Alexander Gruze ◽  
...  
Keyword(s):  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Synergistic Effects ◽  
K562 Cells ◽  
Leukemic Cells ◽  
Kinase Assay ◽  
Thymidine Uptake ◽  
Dependent Manner ◽  
Growth Inhibitory ◽  
Imatinib Resistant

Abstract Chronic myeloid leukemia (CML) is a stem cell disease characterized by the BCR/ABL oncoprotein. The ABL kinase inhibitor imatinib is effective in most patients and considered standard first line therapy. However, not all patients show a long-lasting response. Treatment failure is usually associated with the occurrence of imatinib-resistant mutants of BCR/ABL. For these patients, novel multi-kinase inhibitors such as dasatinib represent alternative treatment options. Still, however, not all patients respond to these drugs, especially when leukemic cells bear the BCR/ABL mutant T315I that confers resistance against most kinase-blockers. Bosutinib is a novel multi-kinase inhibitor that has been described to act growth-inhibitory in ABL-transformed leukemias. In the current study, we examined the effects of bosutinib alone and in combination with dasatinib on growth and survival of CML cells. Bosutinib was found to inhibit 3H-thymidine uptake and thus proliferation in imatinib-sensitive and imatinib-resistant K562 cells in a dose-dependent manner, with identical IC50 values (10–100 nM). Moreover, bosutinib was found to inhibit the growth of primary CML cells and Ba/F3 cells bearing various imatinibresistant mutants of BCR/ABL, except the T315I mutant (IC50&gt;1 μM). The growth-inhibitory effects of bosutinib were found to be associated with signs of apoptosis. Dasatinib showed similar effects on CML cells, and again did not block the growth of subclones bearing BCR/ABL T315I. Unexpectedly, however, we found that bosutinib and dasatinib synergize with each other in producing growth inhibition in primary CML cells exhibiting BCR/ABL T315I at pharmacologic concentrations (0.01–1 μM). Clear synergistic effects were also observed in imatinib-sensitive and imatinib-resistant K562 cells as well as in Ba/F3 cells bearing BCR/ABL T315I. In parallel, we performed multiplexed kinase assays as well as chemical proteomics analysis and mass spectrometry using K562 cells and primary CML cells and coupleable dasatinib and bosutinib analogues. In these experiments, dasatinib and bosutinib were found to express an overlapping, but non-identical profile of target kinases. As expected, both drugs were found to bind to wt ABL, SRC kinases, and TEC-family kinases including BTK. Specific targets preferentially bound and inhibited by bosutinib were STE20s, the FES/FER family, CAMKIIG, PYK2 and TBK1. We were also able to confirm that the dasatinib-targets KIT and PDGFRA are not recognized by bosutinib. Interestingly, whereas wt ABL (IC50&lt;0.5 nM) and most of the ABL mutants tested (H396P, M351T, Q252H, and Y253F) were all completely inhibited by both drugs at 1 μM in the kinase assay, the ABL T315I mutant was inhibited by bosutinib (IC50=26 nM) almost 70 times more potently than by dasatinib. Together, these data show that bosutinib and dasatinib synergize with each other in producing antileukemic effects on CML cells including BCR/ABL T315I+ subclones. These synergistic effects may be explained by differential target kinase profiles and by the fact that bosutinib retains some activity against the BCR/ABL T315I mutant kinase.

The Multi-Kinase/ABL Inhibitor R763/AS703569 Induces DNA Endoreduplication and Apoptosis In Imatinib-Resistant CML Cells and Synergizes with Nilotinib, Dasatinib, and the Plk-1 Inhibitor BI 2536, In Producing Growth Inhibition.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3394-3394
Author(s):  
Karoline V. Gleixner ◽  
Harald Herrmann ◽  
Barbara Peter ◽  
Katharina Blatt ◽  
Karina Schuch ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Research Funding ◽  
Kinase Inhibitors ◽  
K562 Cells ◽  
Aurora Kinase ◽  
Inhibitory Effects ◽  
Growth Inhibitory ◽  
Imatinib Resistant ◽  
Resistant Mutants ◽  
Bi 2536

Abstract Abstract 3394 Resistance to imatinib is a major clinical problem and challenge in advanced chronic myeloid leukemia (CML). In most patients, drug-resistant mutants of BCR/ABL are detectable. Although most of these mutants still are responsive to second generation BCR/ABL kinase inhibitors (KI) such as nilotinib or dasatinib, drug responses are often short-lived. The BCR/ABL mutant T315I confers resistance against all available BCR/ABL KI, including nilotinib and dasatinib. More recent data suggest that several Aurora kinase (AuK) inhibitors block the kinase activity of BCR/ABL T315I. We have examined the growth-inhibitory effects of the AuK/ABL inhibitor R763/AS703569 (Merck-Serono, Darmstadt, Germany) on primary CML cells (chronic phase, n=12), the CML cell line K562, and Ba/F3 cells transfected with various imatinib-resistant mutants of BCR/ABL. As assessed by 3H-thymidine-uptake, R763/AS703569 was found to inhibit proliferation in imatinib-sensitive and imatinib-resistant primary CML cells in all donors tested, in imatinib-resistant and imatinib-responsive K562 cells, and in Ba/F3 cells harbouring various mutants of BCR/ABL (E255K, Y253F, H396P, T315I). The effects of R763/AS703569 on BCR/ABL-transformed cells were dose-dependent with IC50 values ranging between 0.001–0.1 μ M in K562 cells, <0.001-1 μ M in primary CML cells, and 0.001–0.1 μ M in BCR/ABL+ Ba/F3 cells. In all three patients in whom an imatinib-resistant BCR/ABL mutation was detected (one with V379I, one with F359V, and one with T315), R763/AS703569 was found to inhibit growth of primary CML cells at pharmacologic concentrations (IC50: 0.5, 0.005, and 0.05 μ M, respectively). As assessed by flow cytometry, the growth-inhibitory effects of R763/AS703569 were accompanied by DNA endoreduplication and consecutive apoptosis. Western blot experiments using anti-pCrkL antibody were performed and confirmed that R763/AS703569 blocks BCR/ABL activity at 1 μ M in K562 cells and BCR/ABL-transformed Ba/F3 cells. In addition, R763/AS703569 was found to block Aurora kinase A and Lyn phosphorylation in CML cells. By contrast, no effect of R763/AS703569 on phosphorylation or expression of Polo-like kinase-1 (Plk-1) was seen. In a next step, we explored the effects of drug combinations on growth of K562 cells and BCR/ABL-transformed Ba/F3 cells. In these experiments, R763/AS703569 was found to synergize with the ABL/multi-kinase inhibitors nilotinib (Novartis, Basel Switzerland) and dasatinib (Bristol-Myers Squibb, Princeton, NJ) in producing growth inhibition in CML cells (figure). Moreover, R763/AS703569 and the Plk-1 inhibitor BI 2536 (Boehringer Ingelheim, Vienna, Austria) were found to produce synergistic growth-inhibitory effects on CML cells in all samples tested. Synergistic effects of the KI applied were also seen in Ba/F3 cells exhibiting BCR/ABL T315I. In summary, our data show that the novel AuK/ABL inhibitor R763/AS703569 produces growth inhibition and apoptosis in BCR/ABL-transformed cells including those harbouring BCR/ABL T315I or other imatinib-resistant BCR/ABL mutants. Moreover, our data show that R763/AS703569 synergize with other multi-kinase/ABL inhibitors as well as with the Plk-1 inhibitor BI 2536 in producing growth inhibition in imatinib-resistant CML cells. Whether R763/AS703569, applied alone or in combination with other targeted drugs, can produces anti-leukemic effects in patients with advanced CML remains to be determined in clinical trials. Synergistic growth-inhibitory effects of R763/AS703569 and nilotinib in BCR/ABL T315I+ Ba/F3 cells (left), and R763/AS703569 and dasatinib in K562 cells (right). Disclosures: Valent: Novartis: Research Funding; Bristol-Myers Squibb: Research Funding; Merck-Serono: Research Funding.

Ponatinib Exerts Growth-Inhibitory Effects on Neoplastic Mast Cells and Synergizes with Midostaurin in Producing Growth Arrest and Apoptosis,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3497-3497
Author(s):  
Karoline V. Gleixner ◽  
Katharina Blatt ◽  
Barbara Peter ◽  
Emir Hadzijusufovic ◽  
Peter Valent
Keyword(s):  
Mast Cells ◽  
Growth Inhibition ◽  
Leukemia Cell Line ◽  
Dependent Manner ◽  
Inhibitory Effects ◽  
Relative Resistance ◽  
Growth Inhibitory ◽  
Ic50 Values ◽  
Dose Dependent ◽  
Kit D816v

Abstract Abstract 3497 Aggressive systemic mastocytosis (ASM) and mast cell leukemia (MCL) have a poor prognosis. In these patients, neoplastic mast cells (MC) usually harbor the D816V-mutated variant of KIT and are resistant to conventional cytoreductive drugs and to several tyrosine kinase inhibitors (TKI) such as imatinib. More recently, various KIT kinase blockers including midostaurin (PKC412), have been described to overcome KIT D816V-mediated resistance in neoplastic MC. However, despite encouraging first results observed in clinical trials, these novel kinase blockers are unable to induce long-lasting complete remissions in all patients with ASM and MCL. One reason for the poor response in these patients may be the expression and activation of additional KIT-independent pro-oncogenic signalling molecules and pathways that trigger survival of neoplastic MC. Therefore, current research is seeking novel broadly acting drugs and drug combinations directed against the pro-oncogenic signaling machinery of neoplastic MC. Ponatinib (AP24534) is a broadly acting novel multikinase inhibitor that has been shown to exert major anti-leukemic effects in chronic myeloid leukemia. The aim of our current study was to evaluate the effects of ponatinib on growth and survival of neoplastic MC. Ponatinib was applied as single agent or in combination with midostaurin (PKC412). As assessed by Western blotting, ponatinib was found to inhibit KIT-phosphorylation in both subclones of the human MC leukemia cell line HMC-1, namely HMC-1.1 harboring KIT G560V but not KIT D816V, and HMC-1.2 cells harboring KIT G560V and KIT D816V. Interestingly, the D816V mutation of KIT was found to induce relative resistance against ponatinib. Ponatinib was also found to counteract the phosphorylation of Lyn, a Src-kinase that serves as a major KIT-independent signalling molecule and survival factor in neoplastic MC. Activated STAT5 in MC was also blocked by ponatinib in a dose-dependent manner. In a next step, we examined the effects of ponatinib on proliferation of neoplastic MC by 3H-thymidine uptake experiments. Ponatinib was found to induce dose-dependent growth inhibition in both HMC-1 subclones, with higher IC50-values in HMC-1 cells harbouring KIT D816V (IC50: 100–500 nM) compared to cells lacking KIT D816V (IC50: 1–10 nM). Furthermore, ponatinib was found to inhibit the proliferation of primary neoplastic MC isolated from patients with indolent SM (ISM, n=2) and ASM (n=1), with IC50-values ranging between 50 nM and 500 nM. Growth inhibitory effects of ponatinib on neoplastic MC were accompanied by induction of apoptosis as assessed by light microscopy, flow cytometry, and TUNEL assay. Finally, we were able to demonstrate that ponatinib synergizes with midostaurin in producing growth-inhibition and apoptosis in HMC-1.1 cells and HMC-1.2 cells. Synergistic effects obtained with suboptimal concentrations of single agents were accompanied by a complete blockage of all relevant kinase targets tested including KIT, Lyn, and STAT5. In conclusion, ponatinib exerts major growth-inhibitory effects on neoplastic MC. KIT D816V-expressing MC are less sensitive to ponatinib. This relative resistance of MC against ponatinib can be overcome by combining ponatinib with midostaurin in an in vitro assay. Whether the drug-combination also exerts major anti-neoplastic effects in vivo in patients with ASM and MCL remains to be determined. Disclosures: Valent: Novartis: Consultancy, Honoraria, Research Funding.

The Plk-1 Inhibitor BI 2536 Counteracts Proliferation and Viability of CML Cells and Synergizes with Imatinib and Nilotinib (AMN107) in Producing Growth Inhibition.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1046-1046 ◽  
Author(s):  
Karoline V. Gleixner ◽  
Veronika Ferenc ◽  
Alexander Gruze ◽  
Michael Kneidinger ◽  
Christian Baumgartner ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Tyrosine Kinase ◽  
Growth Inhibition ◽  
Peripheral Blood ◽  
Myeloid Leukemia ◽  
K562 Cells ◽  
Mitotic Arrest ◽  
Leukemic Cells ◽  
Imatinib Resistant ◽  
Bi 2536

Abstract Chronic myeloid leukemia (CML) is a hematopoietic stem cell disease in which BCR/ABL enhances growth and survival of leukemic cells. In most patients, the disease can be kept under control by the BCR/ABL tyrosine kinase inhibitor imatinib (STI571; Novartis Basel, Switzerland). However, resistance or intolerance against imatinib may occur during therapy. Therefore, current research is focusing on novel targets and targeted drugs in CML. Polo-like kinase 1 (Plk-1) is a serine/threonine kinase that plays an essential role in mitosis and is expressed in activated/phosphorylated form in various malignancies including acute myeloid leukemia (AML). BI 2536 (Boehringer Ingelheim GmbH, Germany) is a novel selective inhibitor of Plk-1, that is currently tested in AML-trials. In this study, we have evaluated expression and the potential role of Plk-1 as a novel target in CML cells. As assessed by PCR, Plk-1 mRNA was found to be expressed abundantly in primary CML cells and in the CML cell line K562, whereas normal peripheral blood cells did not express detectable levels of Plk-1 mRNA. The Plk-1 protein was detected in primary CML cells and K562 cells by immunocytochemistry. In consecutive experiments, we were able to show that CML cells display phosphorylated Plk-1. As assessed by 3H-thymidine-uptake experiments, BI 2536 was found to inhibit the proliferation of K562 cells in a dose-dependent manner (IC50 5–15 nM). Moreover, BI 2536 was found to inhibit the proliferation of both imatinib-naive (n=6) and imatinib-resistant (n=3) primary CML cells (IC50: 1–15 nM). The growth-inhibitory effect of BI 2536 on CML cells was found to be associated with mitotic arrest, a G2-M cell cycle arrest, and consecutive apoptosis. In normal bone marrow or peripheral blood mononuclear cells, neither mitotic cell arrest nor apoptosis were observed after exposure to BI 2536. In further experiments, primary CML cells were coincubated with BI 2536 plus imatinib or with BI 2536 plus nilotinib (AMN107; Novartis) at fixed ratio of drug concentrations. In these experiments, BI 2536 was found to synergize with both tyrosine kinase inhibitors in counteracting the proliferation of CML cells. In conclusion, our data show that Plk-1 is expressed in activated form in CML cells and plays a role in cell cycle progression and cell viability. Targeting Plk-1 with BI 2536 leads to mitotic arrest, growth inhibition, and apoptosis in imatinib-naive and imatinib-resistant leukemic cells. Moreover, BI 2536 synergizes with imatinib and nilotinib in counteracting the growth of neoplastic cells in CML. Targeting of Plk-1 may be a novel interesting pharmacologic approach to counteract growth of CML cells.

scholarly journals Antiproliferative and Apoptosis-Inducing Activities of Benchalokawichian Remedy Against Doxorubicin-Sensitive and -Resistant Erythromyelogenous Leukemic Cells

2021 ◽  
Vol 20 (3) ◽  
Author(s):  
Wipob Suttana ◽  
Chatubhong Singharachai ◽  
Rawiwan Charoensup ◽  
Narawadee Rujanapun ◽  
Chutima Suya
Keyword(s):  
Cell Cycle ◽  
Multidrug Resistance ◽  
Cell Cycle Arrest ◽  
Cancer Cells ◽  
K562 Cells ◽  
Leukemic Cells ◽  
Drug Resistant ◽  
Normal Cells ◽  
Root Extracts ◽  
Cycle Arrest

Chemotherapy can cause multidrug resistance in cancer cells and is cytotoxic to normal cells. Discovering natural bioactive compounds that are not cytotoxic to normal cells but inhibit proliferation and induce apoptosis in drug- sensitive and drug-resistant cancer cells could overcome these drawbacks of chemotherapy. This study investigated the antiproliferative effects of crude extracts of Benchalokawichian (BLW) remedy and its herbal components against drug-sensitive and drug-resistant cancer cells, cytotoxicity of the extracts toward normal cells, and their ability to induce apoptosis and cell cycle arrest in drug-sensitive and drug-resistant cancer cells. The extracts exhibited antiproliferative activity against doxorubicin-sensitive and doxorubicin-resistant erythromyelogenous leukemic cells (K562 and K562/adr). Tiliacora triandra root, BLW, and Harrisonia perforata root extracts displayed an IC50 of 77.00 ± 1.30, 79.33 ± 1.33, and 87.67 ± 0.67 µg/mL, respectively, against K562 cells. In contrast, Clerodendrum petasites, T. triandra, and H. perforata root extracts displayed the lowest IC50 against K562/adr cells (68.89 ± 0.75, 78.33 ± 0.69, and 86.78 ± 1.92 µg/mL, respectively). The resistance factor of the extracts was lower than that of doxorubicin, indicating that the extracts could overcome the multidrug resistance of cancer cells. Importantly, the extracts were negligibly cytotoxic to peripheral mononuclear cells, indicating minimal adverse effects in normal cells. In addition, these extracts induced apoptosis of K562 and K562/adr cells and caused cell cycle arrest at the G0/G1 phase in K562 cells. Keywords: Antiproliferative, Apoptosis, Benchalokawichian, Cell cycle, Multidrug resistance

scholarly journals Isoform Selective HDAC8 Inhibitor (OCH3) Shows Potency in Selectively Targeting Primary AML Cells

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2944-2944
Author(s):  
Amal Mechaal ◽  
Amudha Ganapathy ◽  
Dolores Mahmud ◽  
Taha Y Taha ◽  
Rajeev Ranjan ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Ex Vivo ◽  
Vehicle Control ◽  
Leukemia Cells ◽  
Apoptotic Cells ◽  
Histone H4 ◽  
Inhibitory Effects ◽  
Growth Inhibitory ◽  
Cd34 Cells

Abstract The treatment outcomes for patients diagnosed with acute myeloid leukemia (AML) are still dismal. Recent advances in understanding AML indicate that the lack of efficacy is primarily due to non-specificity of currently used chemotherapeutics targeting both leukemic stem/progenitor cells (LSC) and normal hematopoietic stem cells (HSC). Thus, a critical barrier is the identification of innovative therapies that selectively target LSC. Histone deacetylase 8 (HDAC8) has been shown to enhance p53 protein deacetylation, which results in inactivation of p53, promoting LSC survival. We hypothesize that enzymatic/non-enzymatic role of HDAC8 is critical for LSC survival but not for HSCs. Then, we characterized our two tetrahydroisoquinoline (TIQ)-based selective HDAC8 inhibitors (HDAC8i) BIP and OCH3 for growth inhibition, apoptosis, activation of caspase 3, integrity of mitochondrial membrane potential (MMP), and acetylation of histone H4 in human leukemia cell lines. The growth inhibitory effects observed in cell lines were validated using bone marrow (BM) or peripheral blood (PB) cells from AML patients. Colony forming cell (CFC) assays were performed using AML BM/PB cells treated with OCH3 or BIP. OCH3 and BIP were also tested for hematotoxicity using normal CB CD34+ cells. Furthermore, we compared class I HDAC isoform engagement in human normal cord blood (CB) CD34+ cells and in SET-2 leukemia cells using our novel photoreactive probe TH1143. In CD34+ cells, TH1143 had higher level of engagement for HDAC1 and 2, whereas engagement of HDAC3 and 8 was minimal. In SET-2 cells, HDAC3 and HDAC8 displayed relatively higher engagement with TH1143 indicating HDAC engagement is likely cell type specific. The biological efficacies of OCH3 at 50uM and BIP at 25uM were noted to exert &gt;50% growth inhibition in KG1 and in K562 leukemia cells. Both OCH3 and BIP significantly increased the number of apoptotic cells and there was an enhanced active caspase-3 activity. Furthermore, OCH3 and BIP treated cells displayed lower red/green ratio in comparison to control, indicative of poor MMP and depolarization to induce apoptosis (Table 1.a). OCH3 and BIP were further validated by using BM/PB cells from AML patients showing growth inhibition. This was also accompanied by increase in apoptotic cells by OCH3 and BIP. In contrast to BIP, OCH3 spared CB CD34+ cells as demonstrated by notably lower growth inhibition, apoptotic cells vs control when compared with primary AML cells from patients. Both OCH3 and BIP displayed minimal inhibition of CFU growth in CD34+ cells. However, HDAC8i induced significant CFU growth inhibition in primary AML samples suggesting that HDAC8i spares normal CFU progenitors but not leukemia progenitors (Table 1.b). Notably, both BIP and OCH3 lack ability to exert acetylation of histone H4, unlike broad spectrum HDAC inhibitor TSA (MFI with OCH3=0.96±0.03, BIP=0.77±0, TSA =1.63±0.15) which is consistent with isoform selectivity of OCH3 and BIP. The leukemia growth inhibitory effects at LSC level was demonstrated using ex vivo OCH3 treated AML patient derived BM/PB cells transplantation in humanized immunodeficient NSGS mice. After 10 to 12 weeks of transplantation mice receiving untreated AML cells had 7.73±2.18% while with OCH3 treatment mice had 4.84±1.37% human CD34+ leukemia cells, a 38% reduction in CD34+ leukemia cells, despite only a single ex vivo exposure to OCH3. Furthermore, in a second model, NSGS humanized mice were transplanted (IV) with primary leukemia cells from AML patients and after 4 weeks injected (IP) with OCH3 or vehicle control. After 12 weeks of transplantation in this second model human primary AML cell burden was 5.74±1.31% (OCH3) and 18.13±12.76% (vehicle control), while mice transplanted with normal CD34+ cells treated similarly with OCH3 or vehicle control displayed no detectable inhibition of human myeloid cell chimerism (OCH3:12.28 ± 3.31% vs vehicle control: 17.92±11.96%). Taken together, our data indicate that HDAC8 isoform inhibitor, OCH3 displayed significant inhibition of primary AML patient derived leukemia cells growth in vitro and in vivo in contrast to normal CD34+ cells. Selective inhibition of HDAC8 is sufficient to cause growth inhibition in primary AML progenitors including LSCs in vivo while sparing normal HSCs thus offer opportunities for further development of HDAC8i as new experimental therapeutics in AML. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Synergistic growth inhibitory effects of interferon-α and lovastatin on bcr-abl positive leukemic cells

2003 ◽  
Author(s):  
Carsten Müller-Tidow ◽  
Michael Kiehl ◽  
Jürgen Sindermann ◽  
Michael Probst ◽  
Nicola Banger ◽  
...  
Keyword(s):  
Leukemic Cells ◽  
Interferon Α ◽  
Inhibitory Effects ◽  
Growth Inhibitory

Relationship between the As2O3 Induced Expression of NF-κB and Drug Resistance in K562/ADR Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4414-4414
Author(s):  
Xiao-hong Zhang ◽  
Li-da Su ◽  
Xiao-ying Zhao ◽  
Qing-hua Lv
Keyword(s):  
Flow Cytometry ◽  
Drug Resistance ◽  
K562 Cells ◽  
Suppressive Effect ◽  
Resistance Mechanisms ◽  
Leukemic Cells ◽  
Ic50 Values ◽  
Induced Apoptosis ◽  
The Relationship ◽  
Cells Cultured

Abstract Summery: Anti-apoptosis is one of drug resistance mechanisms in leukemic cells. It was found in our early study that As2O3 can induce apoptosis of K562 cells, and this effect involve the degradation of IκB-αand consequently the activation of NF-κB. The relationship between drug resistance of leukemic cells and the expression of both IκB-αand NF-κB associated with apoptosis induced by arsenic trioxide(As2O3) was studied in K562 and K562/ADR cells. Methods: Apoptosis was induced in K562 and K562/ADR cells cultured with As2O3 in different concentrations. Western blot was used to analyze the expression of NF-κB in nuclear and IκB-α in cytoplasm of these cells. Apoptosis and degradation of IκB-αprotein were also observed by flow cytometry. Results: The suppressive effect of As2O3 on proliferation of K562/ADR was lower than that in K562 cell, IC50 values were 19.07μmol/L and 5.26μmol/L, respectively. After exposure to As2O3, the ratio of apoptosis cells increased with the concentration of As2O3 in K562 cells, from(13.25±1.83)% to (50.56±8.62)% with variation of As2O3 from 1μmol/L to 4μmol/L(P<0.05). The ratio of apoptosis cells in K562/ADR cultured with 4μmol/L As2O3 was significantly lower than that in K562 cells, (8.00±1.47)% vs. (50.56±8.62)%, (P<0.05). The level of IκB-α in K562 cytoplasm was down-regulated from (88.07±0.99)% to (49.21±0.95)%, (P<0.01) after As2O3 stimulation, while NF-κB in nuclear was up-regulated, that was not found in K562/ADR cells. Conclusion: As2O3 could induce apoptosis of K562 cells, associated with the degradation of IκB-αand the activation of NF-κB. There were resistance to As2O3 induced apoptosis and an abnormal regulation of NF-κB expression by As2O3 in K562/ADR cells.

Sign in / Sign up

Export Citation Format

Share Document