siRNA-mediated down-regulation of iASPP promotes apoptosis induced by etoposide and daunorubicin in leukemia cells expressing wild-type p53

2009 ◽  
Vol 33 (9) ◽  
pp. 1243-1248 ◽  
Author(s):  
Hang Liu ◽  
Min Wang ◽  
Shiyong Diao ◽  
Qing Rao ◽  
Xinwei Zhang ◽  
...  
Keyword(s):  
Leukemia Cells ◽  
Wild Type ◽  
Down Regulation ◽  
Wild Type P53

scholarly journals Down-regulation of Wild-type p53-induced Phosphatase 1 (Wip1) Plays a Critical Role in Regulating Several p53-dependent Functions in Premature Senescent Tumor Cells

2013 ◽  
Vol 288 (23) ◽  
pp. 16212-16224 ◽  
Author(s):  
Elvira Crescenzi ◽  
Zelinda Raia ◽  
Francesco Pacifico ◽  
Stefano Mellone ◽  
Fortunato Moscato ◽  
...  
Keyword(s):  
Dna Damage ◽  
Tumor Cells ◽  
Dna Damage Response ◽  
Critical Role ◽  
Wild Type ◽  
Down Regulation ◽  
Senescent Phenotype ◽  
Response To Chemotherapy ◽  
Damage Response ◽  
Wild Type P53

Premature or drug-induced senescence is a major cellular response to chemotherapy in solid tumors. The senescent phenotype develops slowly and is associated with chronic DNA damage response. We found that expression of wild-type p53-induced phosphatase 1 (Wip1) is markedly down-regulated during persistent DNA damage and after drug release during the acquisition of the senescent phenotype in carcinoma cells. We demonstrate that down-regulation of Wip1 is required for maintenance of permanent G2 arrest. In fact, we show that forced expression of Wip1 in premature senescent tumor cells induces inappropriate re-initiation of mitosis, uncontrolled polyploid progression, and cell death by mitotic failure. Most of the effects of Wip1 may be attributed to its ability to dephosphorylate p53 at Ser15 and to inhibit DNA damage response. However, we also uncover a regulatory pathway whereby suppression of p53 Ser15 phosphorylation is associated with enhanced phosphorylation at Ser46, increased p53 protein levels, and induction of Noxa expression. On the whole, our data indicate that down-regulation of Wip1 expression during premature senescence plays a pivotal role in regulating several p53-dependent aspects of the senescent phenotype.

KW-2449, a novel multikinase inhibitor, suppresses the growth of leukemia cells with FLT3 mutations or T315I-mutated BCR/ABL translocation

Blood ◽  
2009 ◽  
Vol 114 (8) ◽  
pp. 1607-1617 ◽  
Author(s):  
Yukimasa Shiotsu ◽  
Hitoshi Kiyoi ◽  
Yuichi Ishikawa ◽  
Ryohei Tanizaki ◽  
Makiko Shimizu ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Leukemia Cells ◽  
Significant Activity ◽  
Wild Type ◽  
Down Regulation ◽  
Multikinase Inhibitor ◽  
Growth Inhibitory ◽  
Imatinib Resistant ◽  
Flt3 Mutations ◽  
Potent Growth

Abstract KW-2449, a multikinase inhibitor of FLT3, ABL, ABL-T315I, and Aurora kinase, is under investigation to treat leukemia patients. In this study, we examined its possible modes of action for antileukemic effects on FLT3-activated, FLT3 wild-type, or imatinib-resistant leukemia cells. KW-2449 showed the potent growth inhibitory effects on leukemia cells with FLT3 mutations by inhibition of the FLT3 kinase, resulting in the down-regulation of phosphorylated-FLT3/STAT5, G1 arrest, and apoptosis. Oral administration of KW-2449 showed dose-dependent and significant tumor growth inhibition in FLT3-mutated xenograft model with minimum bone marrow suppression. In FLT3 wild-type human leukemia, it induced the reduction of phosphorylated histone H3, G2/M arrest, and apoptosis. In imatinib-resistant leukemia, KW-2449 contributed to release of the resistance by the simultaneous down-regulation of BCR/ABL and Aurora kinases. Furthermore, the antiproliferative activity of KW-2449 was confirmed in primary samples from AML and imatinib-resistant patients. The inhibitory activity of KW-2449 is not affected by the presence of human plasma protein, such as α1-acid glycoprotein. These results indicate KW-2449 has potent growth inhibitory activity against various types of leukemia by several mechanisms of action. Our studies indicate KW-2449 has significant activity and warrants clinical study in leukemia patients with FLT3 mutations as well as imatinib-resistant mutations.

Inhibition of p53-MDM2 Interaction by Small-Molecule Antagonist of MDM2 Effectively Induces Apoptosis in Leukemias.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2536-2536
Author(s):  
Kensuke Kojima ◽  
Marina Konopleva ◽  
Masato Shikami ◽  
Maria Cabreira-Hansen ◽  
C. Ellen Jackson ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Annexin V ◽  
Cell Number ◽  
Leukemia Cells ◽  
P53 Mutations ◽  
Wild Type ◽  
Cycle Arrest ◽  
Wild Type P53 ◽  
Induced Apoptosis

Abstract Alteration of the p53 gene is one of the most frequent events in human tumorigenesis and about 50% of all solid tumors have been reported to carry p53 mutations. The inactivation of p53 in cancer has been associated with poor survival, refractory disease and chemoresistance. p53 mutations rarely occur in hematopoietic malignancies. Instead, MDM2 which is a principal cellular antagonist of p53, is overexpressed in the majority of leukemias. Recently, potent and selective small-molecule antagonists of MDM2, Nutlins, have been identified (Science303:844–888, 2004). Nutlins bind MDM2 in the p53-binding pocket and activate the p53 pathway in human cancer cells with wild-type p53, leading to cell cycle arrest, apoptosis, and growth inhibition of human tumor xenografts in nude mice. In this study, we investigated the potential antileukemic activity of the MDM2 antagonist. Treatment of wild-type p53 OCI-AML-3 cells with 5 μM of an active compound (Nutlin-3a) induced cell cycle arrest and apoptosis as evidenced by flow-cytometric analysis (51% reduction of S-phase at 12 h, 27% sub-G1 DNA content and 57% Annexin V positivity at 48 h). Similar proapoptotic effects were observed in MOLM-13 cells which have wild-type p53, but not in p53-null (HL-60 and U937) or mutant p53 (Raji, Jurkat and NB-4) cells. Nutlin-3a induced apoptosis in a dose- and time-dependent manner, and induced maximal effect on cell cycle arrest at 1 μM. Western blot analysis showed that in OCI-AML-3 cells, wild-type p53 accumulated at 1 h after exposure to Nutlin-3a. Increased levels of MDM2, p21 and Noxa proteins were observed at 1 to 3h. This resulted in cleavage of caspase-9 followed by cleavage of caspase-3. A pharmacologic interaction study between MDM2 inhibitor and Ara-C using a fixed-ratio (1:1) experimental design showed highly synergistic cell growth inhibition (CI = 0.44) and induction of apoptosis (CI = 0.83) in OCI-AML-3 cells. Initial studies conducted in primary leukemia cells demonstrated that Nutlin-3a induced apoptosis in 4 of 5 AML samples tested (68–97% Annexin V induction and 65–93% cell number reduction) and 2 CLL samples (>50% Annexin V induction and 37% and 58% cell number reduction). Since MDM2 protein is overexpressed and p53 is not mutated in the majority of primary leukemia cells, this approach may have therapeutic utility in leukemias.

The Chimeric E2A-HLF Transcription Factor Abrogates p53-Induced Apoptosis in Myeloid Leukemia Cells

Blood ◽  
1998 ◽  
Vol 92 (4) ◽  
pp. 1397-1405
Author(s):  
Rachel A. Altura ◽  
Takeshi Inukai ◽  
Richard A. Ashmun ◽  
Gerard P. Zambetti ◽  
Martine F. Roussel ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
B Cells ◽  
Growth Factor ◽  
Myeloid Leukemia ◽  
Leukemic Cells ◽  
Leukemia Cells ◽  
Wild Type ◽  
Wild Type P53 ◽  
Induced Apoptosis

Leukemic lymphoblasts expressing the E2A-HLF oncoprotein possess wild-type p53 genes, but do not undergo apoptosis in response to DNA damage. Experimentally, E2A-HLF prevents apoptosis due to growth factor deprivation or γ-irradiation in interleukin-3 (IL-3)–dependent murine pro-B cells. To directly test the chimeric protein’s ability to abrogate p53-mediated cell death, we used mouse myeloid leukemia cells (M1p53tsval) that constitutively express a temperature-sensitive (ts) mutant p53 gene and undergo apoptosis when p53 assumes an active wild-type configuration. This effect is blocked by treatment with IL-6, which allows the cells to survive in culture despite wild-type p53 activation. We introduced E2A-HLF into M1p53tsval cells and found that they were resistant to p53-mediated apoptosis and that E2A-HLF effectively substituted for the survival functions of IL-6. The expression of p53-responsive genes such as p21 and Bax was upregulated normally, suggesting that E2A-HLF acts downstream of p53 to block execution of the p53-induced apoptotic program. NFIL3, a growth factor-regulated bZIP protein that binds to the same DNA-consensus site as E2A-HLF, delays apoptosis in IL-3–dependent pro-B cells deprived of growth factor. By contrast, in the present study, enforced expression of NFIL3 failed to protect M1p53tsval cells from p53-dependent apoptosis and actively antagonized the ability of IL-6 to rescue cells from that fate, consistent with its role as either a transcriptional repressor or activator, depending on the cell type in which it is expressed. We conclude that the E2A-HLF chimera abrogates p53-induced apoptosis in leukemic cells, possibly through the transcriptional modulation of cell death pathways that are activated by p53 in response to DNA damage. © 1998 by The American Society of Hematology.

The Chimeric E2A-HLF Transcription Factor Abrogates p53-Induced Apoptosis in Myeloid Leukemia Cells

Blood ◽  
1998 ◽  
Vol 92 (4) ◽  
pp. 1397-1405 ◽  
Author(s):  
Rachel A. Altura ◽  
Takeshi Inukai ◽  
Richard A. Ashmun ◽  
Gerard P. Zambetti ◽  
Martine F. Roussel ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
B Cells ◽  
Growth Factor ◽  
Myeloid Leukemia ◽  
Leukemic Cells ◽  
Leukemia Cells ◽  
Wild Type ◽  
Wild Type P53 ◽  
Induced Apoptosis

Abstract Leukemic lymphoblasts expressing the E2A-HLF oncoprotein possess wild-type p53 genes, but do not undergo apoptosis in response to DNA damage. Experimentally, E2A-HLF prevents apoptosis due to growth factor deprivation or γ-irradiation in interleukin-3 (IL-3)–dependent murine pro-B cells. To directly test the chimeric protein’s ability to abrogate p53-mediated cell death, we used mouse myeloid leukemia cells (M1p53tsval) that constitutively express a temperature-sensitive (ts) mutant p53 gene and undergo apoptosis when p53 assumes an active wild-type configuration. This effect is blocked by treatment with IL-6, which allows the cells to survive in culture despite wild-type p53 activation. We introduced E2A-HLF into M1p53tsval cells and found that they were resistant to p53-mediated apoptosis and that E2A-HLF effectively substituted for the survival functions of IL-6. The expression of p53-responsive genes such as p21 and Bax was upregulated normally, suggesting that E2A-HLF acts downstream of p53 to block execution of the p53-induced apoptotic program. NFIL3, a growth factor-regulated bZIP protein that binds to the same DNA-consensus site as E2A-HLF, delays apoptosis in IL-3–dependent pro-B cells deprived of growth factor. By contrast, in the present study, enforced expression of NFIL3 failed to protect M1p53tsval cells from p53-dependent apoptosis and actively antagonized the ability of IL-6 to rescue cells from that fate, consistent with its role as either a transcriptional repressor or activator, depending on the cell type in which it is expressed. We conclude that the E2A-HLF chimera abrogates p53-induced apoptosis in leukemic cells, possibly through the transcriptional modulation of cell death pathways that are activated by p53 in response to DNA damage. © 1998 by The American Society of Hematology.

scholarly journals Down-Regulation of β-Catenin by Activated p53

2001 ◽  
Vol 21 (20) ◽  
pp. 6768-6781 ◽  
Author(s):  
Einat Sadot ◽  
Benjamin Geiger ◽  
Moshe Oren ◽  
Avri Ben-Ze'ev
Keyword(s):  
Target Genes ◽  
Glycogen Synthase ◽  
Wnt Signaling Pathway ◽  
Inhibitory Effect ◽  
Dominant Negative ◽  
Wild Type ◽  
Adenomatous Polyposis Coli Protein ◽  
Down Regulation ◽  
P53 Expression ◽  
Wild Type P53

ABSTRACT β-Catenin is a cytoplasmic protein that participates in the assembly of cell-cell adherens junctions by binding cadherins to the actin cytoskeleton. In addition, it is a key component of the Wnt signaling pathway. Activation of this pathway triggers the accumulation of β-catenin in the nucleus, where it activates the transcription of target genes. Abnormal accumulation of β-catenin is characteristic of various types of cancer and is caused by mutations either in the adenomatous polyposis coli protein, which regulates β-catenin degradation, or in the β-catenin molecule itself. Aberrant accumulation of β-catenin in tumors is often associated with mutational inactivation of the p53 tumor suppressor. Here we show that overexpression of wild-type p53, by either transfection or DNA damage, down-regulates β-catenin in human and mouse cells. This effect was not obtained with transcriptionally inactive p53, including a common tumor-associated p53 mutant. The reduction in β-catenin level was accompanied by inhibition of its transactivation potential. The inhibitory effect of p53 on β-catenin is apparently mediated by the ubiquitin-proteasome system and requires an active glycogen synthase kinase 3β (GSK3β). Mutations in the N terminus of β-catenin which compromise its degradation by the proteasomes, overexpression of dominant-negative ΔF-β-TrCP, or inhibition of GSKβ activity all rendered β-catenin resistant to down-regulation by p53. These findings support the notion that there will be a selective pressure for the loss of wild-type p53 expression in cancers that are driven by excessive accumulation of β-catenin.

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