scholarly journals Downregulation of Signal Regulatory Protein Alfa 1 in K562 Cells Results in the Aberrant Cell Growth in Low Serum Culture

2021 ◽  
Vol 15 ◽  
Author(s):  
Shinichiro Takahashi
Keyword(s):  
Cell Growth ◽  
Regulatory Protein ◽  
K562 Cells ◽  
Aberrant Cell ◽  
Low Serum

The Cellular Labile Iron Pool and Intracellular Ferritin in K562 Cells

Blood ◽  
1999 ◽  
Vol 94 (6) ◽  
pp. 2128-2134 ◽  
Author(s):  
Abraham M. Konijn ◽  
Hava Glickstein ◽  
Boris Vaisman ◽  
Esther G. Meyron-Holtz ◽  
Itzchak N. Slotki ◽  
...  
Keyword(s):  
Biological Effects ◽  
Ferritin Level ◽  
Regulatory Protein ◽  
Iron Chelation ◽  
K562 Cells ◽  
Iron Chelator ◽  
Labile Iron Pool ◽  
Cellular Iron ◽  
Labile Iron ◽  
Iron Pool

Abstract The labile iron pool (LIP) harbors the metabolically active and regulatory forms of cellular iron. We assessed the role of intracellular ferritin in the maintenance of intracellular LIP levels. Treating K562 cells with the permeant chelator isonicotinoyl salicylaldehyde hydrazone reduced the LIP from 0.8 to 0.2 μmol/L, as monitored by the metalo-sensing probe calcein. When cells were reincubated in serum-free and chelator-free medium, the LIP partially recovered in a complex pattern. The first component of the LIP to reappear was relatively small and occurred within 1 hour, whereas the second was larger and relatively slow to occur, paralleling the decline in intracellular ferritin level (t½= 8 hours). Protease inhibitors such as leupeptin suppressed both the changes in ferritin levels and cellular LIP recovery after chelation. The changes in the LIP were also inversely reflected in the activity of iron regulatory protein (IRP). The 2 ferritin subunits, H and L, behaved qualitatively similarly in response to long-term treatments with the iron chelator deferoxamine, although L-ferritin declined more rapidly, resulting in a 4-fold higher H/L-ferritin ratio. The decline in L-ferritin, but not H-ferritin, was partially attenuated by the lysosomotrophic agent, chloroquine; on the other hand, antiproteases inhibited the degradation of both subunits to the same extent. These findings indicate that, after acute LIP depletion with fast-acting chelators, iron can be mobilized into the LIP from intracellular sources. The underlying mechanisms can be kinetically analyzed into components associated with fast release from accessible cellular sources and slow release from cytosolic ferritin via proteolysis. Because these iron forms are known to be redox-active, our studies are important for understanding the biological effects of cellular iron chelation.

Variation of p21, P-Gp Expression in K562/A02 Cell Line with Tetrandrine

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5066-5066
Author(s):  
Bao-An Chen ◽  
Jing Li ◽  
Jian Cheng ◽  
Feng Gao ◽  
Wen-lin Xu ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Cell Growth ◽  
Cell Line ◽  
Clinical Application ◽  
K562 Cells ◽  
Rt Pcr ◽  
P21 Protein ◽  
Mtt Method ◽  
Mdr1 Mrna

Abstract Object: To study the variation of p21, P-gp expression in reversion of multidrug resistance of K562/A02 leukemic line with different concentration of tetrandrine(TET), to provide new theoretic evidence for the clinical application of TET. Methods: The IC50 (the concentration causing 50% inhibition of cell growth) of DNR was analyzed by MTT method; The Expressions of p21 were assayed by westernblot; The Expressions of P-gp were assayed by FCM; The expressions of mdr1 were assayed by RT-PCR; The variation of p21 was accentuation with the accrescence concentration of TET(P <0.05). Results: The variation of p21 protein in K562/A02 cells was accentuation with the accrescence concentration of TET(p<0.05), Mdr1 mRNA was lowly displayed in K562 cells and highly displayed in K562/A02 cells(p<0.01), the variation of mdr1 was attenuation with the accrescence concentration of TET(p<0.05); P-gp was lowly displayed in K562 cells and highly displayed in K562/A02 cells(p<0.01), the variation of P-gp was attenuation with the accrescence concentration of TET(p<0.05). Conclusion: TET may reverse multidrug resistance of K562/A02 cells by the regulation of p21,P-gp and mdr1.

Activity of the Aurora Kinase Inhibitor, MLN8237 (alisertib) Alone or in Combination with Ponatinib Against Imatinib-Resistant BCR-ABL-Positive Cells

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1333-1333
Author(s):  
Seiichi Okabe ◽  
Tetsuzo Tauchi ◽  
Seiichiro Katagiri ◽  
Yuko Tanaka ◽  
Kazuma Ohyashiki
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Growth Inhibition ◽  
Kinase Inhibitor ◽  
K562 Cells ◽  
Aurora Kinase ◽  
Dependent Manner ◽  
Cell Growth Inhibition ◽  
Cycle Arrest ◽  
T315i Mutation

Abstract Abstract 1333 Chronic myeloid leukemia (CML) is characterized by cytogenetic aberration (Philadelphia chromosome: Ph) and chimeric tyrosine kinase BCR-ABL. ABL tyrosine kinase inhibitor, imatinib has demonstrated the potency against CML patients. However, resistance to imatinib can develop in CML patients due to BCR-ABL point mutations. One of T315I mutation is resistant to currently available ABL tyrosine kinase inhibitors. Therefore, new approach against T315I mutant may improve the outcome of Ph-positive leukemia patients. Aurora kinases are serine/threonine kinases and upregulated in many malignancies including leukemia, and play an important role in cell cycle control and tumor proliferations. Because Aurora kinases are overexpressed in leukemia cells, Aurora kinases may present attractive targets for leukemia treatment. One of Aurora kinase inhibitor, MLN8237 (alisertib) is an oral and selective Aurora kinase A inhibitor and is currently being investigated in a pivotal phase 3 clinical trial against hematological malignancies. We suggested that alisertib mediated inhibition Aurora kinase activity and in combination with ponatinib, also known as AP24534 may abrogate the proliferation and survival of Ph-positive cells including T315I mutation. In this study, we investigated the combination therapy with a ponatinib and an alisertib by using the BCR-ABL positive cell line, K562, murine Ba/F3 cell line which was transfected with T315I mutant, ponatinib resistant Ba/F3 cells and T315I primary sample. Protein expression of Aurora A and B were increased in Ph-positive leukemia cells. 72 hours treatment of alisertib exhibits cell growth inhibition and induced apoptosis against K562 cells in a dose dependent manner. Alisertib also induced cell cycle arrest. The treatment of ponatinib exhibits cell growth inhibition partially against K562 cells in the presence of feeder cell (HS-5) conditioned media. We found that the treatment of alisertib abrogated the protective effects of HS-5 conditioned media in K562 cells. We investigated the alisertib activity against T315I positive cells. Alisertib potently induced cell growth inhibition of Ba/F3 cells ectopically expressing T315I mutation and induced cell cycle arrest. We investigated the efficacy between ponatinib and alisertib by using these cell lines. Combined treatment of Ba/F3 T315I cells with ponatinib and alisertib caused significantly more cytotoxicity than each drug alone. Ponatinib and alisertib were also effective against T315I primary samples. We examined the intracellular signaling of alisertib. Phosphorylation of Aurora A was inhibited in a time dependent manner. We also found the phosphorylation of histone H3 was also reduced in a dose dependent manner suggested that high concentration of alisertib also inhibits Aurora B activity. We next investigated by using ponatinib resistant Ba/F3 cells. In the ponatinib resistant cell lines, IC50 of ponatinib was up to 200 nM. BCR-ABL triple point mutations (T315I, E255K and Y253H) were detected by direct sequence analysis. The treatment of alisertib exhibits cell growth inhibition against Ba/F3 ponatinib resistant cells in the dose dependent manner. Alisertib induced cell cycle arrest in ponatinib resistant cells. Combined treatment of Ba/F3 ponatinib resistant cells with ponatinib and alisertib caused significantly more cytotoxicity. To assess the activity of alisertib and ponatinib, we performed to test on CML tumor formation in mice. We injected nude mice subcutaneously with 1×107 Ba/F3 T315I cells. A dose of 30 mg/kg/day p.o of ponatinib and 30 mg/kg/day p.o of alisertib inhibited tumor growth and reduced tumor volume compared with control mice. The treatments were well tolerated with no animal health concerns observed indicating the feasibility of alisertib combination strategies in the clinic. Data from this study suggested that administration of the ponatinib and Aurora inhibitor, alisertib may be a powerful strategy against BCR-ABL mutant cells including T315I. Disclosures: No relevant conflicts of interest to declare.

Dual HDAC and PI3K Inhibitor, CUDC-907 Alone or in Combination with ABL Tyrosine Kinase Inhibitor Against ABL Tyrosine Kinase Inhibitor Resistant Leukemia Cells

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3693-3693
Author(s):  
Seiichi Okabe ◽  
Tetsuzo Tauchi ◽  
Yuko Tanaka ◽  
Juri Sakuta ◽  
Kazuma Ohyashiki
Keyword(s):  
Cell Growth ◽  
Growth Inhibition ◽  
Tyrosine Kinase Inhibitor ◽  
Kinase Inhibitor ◽  
K562 Cells ◽  
Leukemia Cells ◽  
Cell Growth Inhibition ◽  
Abl Tyrosine Kinase ◽  
Abl Tyrosine Kinase Inhibitor ◽  
Dose Dependent

Abstract Introduction: Chronic myeloid leukemia (CML) is characterized by the t(9:22) translocation known as the Philadelphia chromosome (Ph). ABL tyrosine kinase inhibitor (TKI), imatinib and second-generation ABL TKIs, nilotinib and dasatinib have demonstrated the potency against CML patients. However, resistance to ABL TKI can develop in CML patients due to BCR-ABL point mutations. Moreover, ABL TKIs do not eliminate the leukemia stem cells (LSCs). Therefore, new approach against BCR-ABL mutant cells and LSCs may improve the outcome of Ph-positive leukemia patients. In eukaryotic cells, histone acetylation/deacetylation is important in transcriptional regulation. Chromatin acetylation is controlled by the opposing effects of two families of enzymes: histone acetyltransferases (HAT) and histone deacetylases (HDACs). Deregulation of HDAC activity may be a cause of malignant disease in humans. Phosphoinositide 3-kinase (PI3K) pathway also regulates cell metabolism, proliferation and survival. Furthermore, aberrant activation of PI3K signaling pathway has been shown to be important in initiation maintenance of human cancers. CUDC-907 is an oral inhibitor of class I PI3K as well as class I and II HDAC enzymes. CUDC-907 is currently being investigated in a pivotal phase 1 clinical trial against hematological malignancies such as malignant lymphoma. We suggested that CUDC-907 mediated inhibition PI3K and HDAC activity and in combination with ABL TKIs may abrogate the proliferation and survival of Ph-positive leukemia cells including T315I mutation and ABL TKI resistant. Materials and methods: In this study, we investigated the combination therapy with a CUDC-907 and an ABL TKIs (imatinib, nilotinib and ponatinib) by using the BCR-ABL positive cell line, K562, murine Ba/F3 cell line which was transfected with T315I mutant, nilotinib resistant K562 and ponatinib resistant Ba/F3 cells and primary samples. Results: The treatment of imatinib, nilotinib and ponatinib exhibits cell growth inhibition partially against K562 cells in the presence of feeder cell (HS-5). We found that mRNA of PI3K subunit is significantly increased after a co-culture with HS-5 in K562 and primary CD34 positive CML samples. 72 h treatment of CUDC-907 exhibits cell growth inhibition and induced apoptosis against K562 cells in a dose dependent manner. We examined the intracellular signaling after treatment of CUDC-907. Phosphorylation of JNK, histone acetylation and activity of caspase 3, poly (ADP-ribose) polymerase (PARP) was increased. Anti-apoptotic protein, Mcl-1 was decreased in a dose dependent. We next investigated the efficacy between imatinib and CUDC-907 by using these cell line. Combined treatment of K562 cells with imatinib and CUDC-907 caused significantly more cytotoxicity than each drug alone. Caspase activity was increased and Akt activity was reduced. Phosphorylation of BCR-ABL, Crk-L was reduced and cleaved PARP was increased after imatinib and CUDC-907 treatment. We investigated the CUDC-907 activity against T315I positive cells. CUDC-907 potently induced cell growth inhibition of Ba/F3 T315I cells in a dose dependent manner. Combined treatment of Ba/F3 T315I cells with ponatinib and CUDC-907 caused significantly more cytotoxicity than each drug alone. Caspase activity was increased and Akt activity was reduced after ponatinib and CUDC-907 treatment. To assess the activity of ponatinib and CUDC-907, we performed to test on tumor formation in mice. We injected nude mice subcutaneously with Ba/F3 T315I mutant cells. A dose of 20 mg/kg/day p.o of ponatinib and 30 mg/kg/day p.o of CUDC-907 inhibited tumor growth and reduced tumor volume compared with control mice. The treatments were well tolerated with no animal health concerns observed. We also found that the treatment of CUDC-907 exhibits cell growth inhibition against Ba/F3 ponatinib resistant cells, K562 nilotinib resistant cells, T315I mutant primary samples and CD34 positive CML samples. Conclusion: These results indicated that administration of the dual PI3K and HDAC inhibitor, CUDC-907 may be a powerful strategy against ABL TKI resistant cells including T315I mutation and enhance cytotoxic effects of ABL TKI against those Ph-positive leukemia cells. Disclosures No relevant conflicts of interest to declare.

Inhibitory Effect of RNAi on Expression of bcr/abl Oncogene in K562 Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4850-4850
Author(s):  
Chun Wang ◽  
Xiaoxia Ma ◽  
Ju Wei ◽  
Youwen Qin ◽  
Shike Yan
Keyword(s):  
Cell Growth ◽  
Transfection Efficiency ◽  
Mrna Level ◽  
Flow Cytometric Analysis ◽  
K562 Cells ◽  
Mrna Levels ◽  
Small Interfering Rnas ◽  
Obvious Effect ◽  
Western Blots ◽  
Oncogene Expression

Abstract The translocation t(9;22) can be found in 95% patients with chronic myeloid leukemia (CML). The resulting hybrid gene bcr/abl codes for a fusion protein with tyrosine kinase activity which activates signal transduction pathways, leading to uncontrolled cell growth. A promising anti-gene technology-RNA interference (RNAi) reported in recent years can disrupts the expression of the targeted cellular gene in a complicated manner in a variety of organisms and cell types. To inhibit CML bcr/abl oncogene expression with RNAi, we used chemically synthesized anti-bcr/abl small interfering RNAs( siRNAs), mismatch control siRNAs having the three point mutations to transfect the K562 cells for different time through the electroporation. EGFP plasmid was used as a positive control and the amount of fluorescently stained cells was determined by FCM. Inhibitory effects of siRNAs were demonstrated by real-time quantitative RT-PCR and Western blots. Cell proliferation was measured by means of MTT assay and apoptosis was determined by Annexin V-FITC assay. The transfection efficiency was about 70%. The synthesized siRNAs inhibited CML bcr/abl oncogene expression at both mRNA and protein levels. The anti-bcr/abl siRNAs reduced the bcr/abl mRNA level by 67%–72% without an obvious effect on abl mRNA levels. The K562 cells electroporated with anti-bcr/abl siRNAs contained less BCR/ABL protein than cells electroporated with mismatch control siRNAs or without any siRNAs. P210 was reduced to a very low level in Western blots, whereas the wild-type ABL protein was not influenced by the anti-bcr/abl siRNAs. Depletion of bcr/abl leading to increased apoptosis and reduction of cell viability. The flow cytometric analysis showed that the percentage of dead and apoptosic cells induced by anti-bcr/abl siRNAs for 24hrs and 48hrs were 42.10% and 53.33%, respectively, including 15.05% and 19.47% of the preliminary apoptosis cells, respectively. A significant induction of apoptosis was observed after transfection compared with untreated control(1.00%)and the mismatch control siRNAs (2.98%) (p<0.05). Anti-bcr/abl siRNAs inhibited cell growth of the K562 cells and the inhibitory rate was 47% and 56%, 24h and 48h after transfection respectively, whereas the mismatch control siRNAs had no such effect on K562 cells. At the cell level, inhibition of CML bcr/abl oncogene expression by chemically synthesized siRNAs provides the new method for anti-leukemia study. Therefore, siRNAs may be potent tools for gene-specific modality against CML.

Synthesis and Antiproliferative Activities of Novel 2-Phenylaminopyrimidine (PAP) Derivatives

2013 ◽  
Vol 834-836 ◽  
pp. 563-567
Author(s):  
Sheng Chang
Keyword(s):  
Cell Growth ◽  
Growth Inhibitor ◽  
K562 Cells ◽  
Hl60 Cells ◽  
Chronicmyeloid Leukemia ◽  
Antiproliferative Activities

A series of novel 2-phenylaminopyrimidine (PAP) derivatives structurally related to Imatinib were designed and synthesized. The abilities of these compounds to inhibit proliferation were tested in human chronicmyeloid leukemia K562 cells and HL60cells. Compound (10c) was the most effective cell growth inhibitor in inhibiting K562 cells and compound (10f) was the most effective cell growth inhibitor in inhibiting HL60 cells.

scholarly journals The hydroxyurea-induced small GTP-binding protein SAR modulates γ-globin gene expression in human erythroid cells

Blood ◽  
2005 ◽  
Vol 106 (9) ◽  
pp. 3256-3263 ◽  
Author(s):  
Delia C. Tang ◽  
Jianqiong Zhu ◽  
Wenli Liu ◽  
Kyung Chin ◽  
Jun Sun ◽  
...  
Keyword(s):  
Cell Growth ◽  
Molecular Mechanisms ◽  
Binding Protein ◽  
Globin Gene ◽  
K562 Cells ◽  
Pi3 Kinase ◽  
Erythroid Cell ◽  
Erythroid Cells ◽  
Gtp Binding Protein ◽  
Gtp Binding

AbstractHydroxyurea (HU), a drug effective in the treatment of sickle cell disease, is thought to indirectly promote fetal hemoglobin (Hb F) production by perturbing the maturation of erythroid precursors. The molecular mechanisms involved in HU-mediated regulation of γ-globin expression are currently unclear. We identified an HU-induced small guanosine triphosphate (GTP)–binding protein, secretion-associated and RAS-related (SAR) protein, in adult erythroid cells using differential display. Stable SAR expression in K562 cells increased γ-globin mRNA expression and resulted in macrocytosis. The cells appeared immature. SAR-mediated induction of γ-globin also inhibited K562 cell growth by causing arrest in G1/S, apoptosis, and delay of maturation, cellular changes consistent with the previously known effects of HU on erythroid cells. SAR also enhanced both γ- and β-globin transcription in primary bone marrow CD34+ cells, with a greater effect on γ-globin than on β-globin. Although up-regulation of GATA-2 and p21 was observed both in SAR-expressing cells and HU-treated K562 cells, phosphatidylinositol 3 (PI3) kinase and phosphorylated ERK were inhibited specifically in SAR-expressing cells. These data reveal a novel role of SAR distinct from its previously known protein-trafficking function. We suggest that SAR may participate in both erythroid cell growth and γ-globin production by regulating PI3 kinase/extracellular protein–related kinase (ERK) and GATA-2/p21-dependent signal transduction pathways.

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