HHEX promotes myeloid transformation in cooperation with mutant ASXL1

Additional sex combs-like 1 (ASXL1), an epigenetic modulator, is frequently mutated in myeloid neoplasms. Recent analyses of mutant ASXL1 conditional knock-in (ASXL1-MT-KI) mice suggested that ASXL1-MT alone is insufficient for myeloid transformation. In our previous study, we utilized retrovirus-mediated insertional mutagenesis, which exhibited susceptibility of ASXL1-MT-KI hematopoietic cells to transform into myeloid leukemia cells. In this screening, we identified Hematopoietically expressed homeobox (HHEX) gene as one of the common retrovirus integration sites. In this study, we investigated the potential cooperation between ASXL1-MT and HHEX in myeloid leukemogenesis. Expression of HHEX enhanced proliferation of ASXL1-MT expressing HSPCs by inhibiting apoptosis and blocking differentiation, whereas it showed only modest effect in normal HSPCs. Moreover, ASXL1-MT and HHEX accelerated the development of RUNX1-ETO9a and FLT3-ITD leukemia. Conversely, HHEX depletion profoundly attenuated the colony-forming activity and leukemogenicity of ASXL1-MT-expressing leukemia cells. Mechanistically, we identified MYB and ETV5 as downstream targets for ASXL1-MT and HHEX by using transcriptome and ChIP-seq analyses. Moreover, we found that expression of ASXL1-MT enhanced the binding of HHEX to the promoter loci of MYB or ETV5 via reducing H2AK119ub. Depletion of MYB or ETV5 induced apoptosis or differentiation in ASXL1-MT-expressing leukemia cells, respectively. In addition, ectopic expression of MYB or ETV5 reversed the reduced colony-forming activity of HHEX-depleted ASXL1-MT-expressing leukemia cells. These findings indicated that the HHEX-MYB/ETV5 axis promotes myeloid transformation in ASXL1-mutated preleukemia cells.

Download Full-text

Inhibition of Bcl-2 antiapoptotic members by obatoclax potently enhances sorafenib-induced apoptosis in human myeloid leukemia cells through a Bim-dependent process

Blood ◽

10.1182/blood-2011-09-378141 ◽

2012 ◽

Vol 119 (25) ◽

pp. 6089-6098 ◽

Cited By ~ 66

Author(s):

Mohamed Rahmani ◽

Mandy Mayo Aust ◽

Elisa Attkisson ◽

David C. Williams ◽

Andrea Ferreira-Gonzalez ◽

...

Keyword(s):

Myeloid Leukemia ◽

Fluorescent Protein ◽

Ectopic Expression ◽

Leukemia Cells ◽

Down Regulation ◽

Multikinase Inhibitor ◽

Cd34 Cells ◽

Human Acute Myeloid Leukemia ◽

Induced Apoptosis ◽

Green Fluorescent

Abstract Interactions between the multikinase inhibitor sorafenib and the BH3-mimetic obatoclax (GX15-070) were examined in human acute myeloid leukemia (AML) cells. Treatment with sorafenib/obatoclax induced pronounced apoptosis in and reduced the clonogenic growth of multiple AML lines and primary AML cells but not normal CD34+ cells. Sorafenib triggered rapid and pronounced Mcl-1 down-regulation accompanied by enhanced binding of Bim to Bcl-2 and Bcl-xL, effects that were abolished by obatoclax coadministration. Notably, shRNA knockdown of Bim, Bak, or Bax, but not Noxa, significantly attenuated obatoclax/sorafenib lethality, whereas ectopic expression of Mcl-1 exerted a protective effect. Furthermore, exposure of leukemia cells to sorafenib and obatoclax markedly induced autophagy, reflected by rapid and pronounced LC3 processing and LC3–green fluorescent protein (GFP) punctate formation. Multiple autophagy inhibitors or VPS34 knockdown, significantly potentiated sorafenib/obatoclax lethality, indicating a cytoprotective role for autophagy in this setting. Finally, studies in a xenograft mouse model revealed that combined sorafenib/obatoclax treatment markedly reduced tumor growth and significantly prolonged survival in association with Mcl-1 down-regulation and apoptosis induction, whereas agents administered individually had only modest effects. These findings suggest that combining sorafenib with agents that inhibit Mcl-1 and Bcl-2/Bcl-xL such as obatoclax may represent a novel and potentially effective strategy in AML.

Download Full-text

Mechanistic role of heat shock protein 70 in Bcr-Abl–mediated resistance to apoptosis in human acute leukemia cells

Blood ◽

10.1182/blood-2004-05-2041 ◽

2005 ◽

Vol 105 (3) ◽

pp. 1246-1255 ◽

Cited By ~ 100

Author(s):

Fei Guo ◽

Celia Sigua ◽

Purva Bali ◽

Prince George ◽

Warren Fiskus ◽

...

Keyword(s):

Heat Shock ◽

Heat Shock Protein ◽

Myeloid Leukemia ◽

Blast Crisis ◽

Ectopic Expression ◽

Binding Activity ◽

Dominant Negative ◽

Leukemia Cells ◽

Dna Binding Activity ◽

Induced Apoptosis

AbstractBcr-Abl–expressing primary or cultured leukemia cells display high levels of the antiapoptotic heat shock protein (hsp) 70 and are resistant to cytarabine (Ara-C), etoposide, or Apo-2L/TRAIL (TNF-related apoptosis-inducing ligand)–induced apoptosis. Conversely, a stable expression of the cDNA of hsp70 in the reverse orientation attenuated not only hsp70 but also signal transducers and activators of transcription 5 (STAT5) and Bcl-xL levels. This increased apoptosis induced by cytarabine, etoposide, or Apo-2L/TRAIL. Ectopic expression of hsp70 in HL-60 cells (HL-60/hsp70) inhibited Ara-C and etoposide-induced Bax conformation change and translocation to the mitochondria; attenuated the accumulation of cytochrome c, Smac, and Omi/HtrA2 in the cytosol; and inhibited the processing and activity of caspase-9 and caspase-3. Hsp70 was bound to death receptors 4 and 5 (DR4 and DR5) and inhibited Apo-2L/TRAIL-induced assembly and activity of the death-inducing signaling complex (DISC). HL-60/hsp70 cells exhibited increased levels and DNA binding activity of STAT5, which was associated with high levels of Pim-2 and Bcl-xL and resistance to apoptosis. Expression of the dominant negative (DN) STAT5 resensitized HL-60/hsp70 cells to cytarabine, etoposide, and Apo-2L/TRAIL–induced apoptosis. Collectively, these findings suggest that hsp70 inhibits apoptosis upstream and downstream of the mitochondria and is a promising therapeutic target for reversing drug-resistance in chronic myeloid leukemia-blast crisis and acute myeloid leukemia cells. (Blood. 2005;105:1246-1255)

Download Full-text

Inhibition of Autophagy Enhances the Antitumor Effect of Thioridazine in Acute Lymphoblastic Leukemia Cells

Life ◽

10.3390/life11040365 ◽

2021 ◽

Vol 11 (4) ◽

pp. 365

Author(s):

Carina Colturato-Kido ◽

Rayssa M. Lopes ◽

Hyllana C. D. Medeiros ◽

Claudia A. Costa ◽

Laura F. L. Prado-Souza ◽

...

Keyword(s):

Cell Death ◽

Acute Lymphoblastic Leukemia ◽

Lymphoblastic Leukemia ◽

Clinical Problem ◽

Jurkat Cells ◽

Leukemia Cells ◽

Peripheral Mononuclear Blood ◽

Induced Apoptosis ◽

Cure Rates

Acute lymphoblastic leukemia (ALL) is an aggressive malignant disorder of lymphoid progenitor cells that affects children and adults. Despite the high cure rates, drug resistance still remains a significant clinical problem, which stimulates the development of new therapeutic strategies and drugs to improve the disease outcome. Antipsychotic phenothiazines have emerged as potential candidates to be repositioned as antitumor drugs. It was previously shown that the anti-histaminic phenothiazine derivative promethazine induced autophagy-associated cell death in chronic myeloid leukemia cells, although autophagy can act as a “double-edged sword” contributing to cell survival or cell death. Here we evaluated the role of autophagy in thioridazine (TR)-induced cell death in the human ALL model. TR induced apoptosis in ALL Jurkat cells and it was not cytotoxic to normal peripheral mononuclear blood cells. TR promoted the activation of caspase-8 and -3, which was associated with increased NOXA/MCL-1 ratio and autophagy triggering. AMPK/PI3K/AKT/mTOR and MAPK/ERK pathways are involved in TR-induced cell death. The inhibition of the autophagic process enhanced the cytotoxicity of TR in Jurkat cells, highlighting autophagy as a targetable process for drug development purposes in ALL.

Download Full-text

Blue light-induced apoptosis of human promyelocytic leukemia cells via the mitochondrial-mediated signaling pathway

Oncology Letters ◽

10.3892/ol.2018.8162 ◽

2018 ◽

Cited By ~ 1

Author(s):

Jianjian Zhuang ◽

Yange Liu ◽

Qingxia Yuan ◽

Junsong Liu ◽

Yan Liu ◽

...

Keyword(s):

Signaling Pathway ◽

Blue Light ◽

Promyelocytic Leukemia ◽

Leukemia Cells ◽

Induced Apoptosis

Download Full-text

Cancer cells activate p53 in response to 10-formyltetrahydrofolate dehydrogenase expression

Biochemical Journal ◽

10.1042/bj20050533 ◽

2005 ◽

Vol 391 (3) ◽

pp. 503-511 ◽

Cited By ~ 27

Author(s):

Natalia V. Oleinik ◽

Natalia I. Krupenko ◽

David G. Priest ◽

Sergey A. Krupenko

Keyword(s):

Cancer Cells ◽

Ectopic Expression ◽

A549 Cells ◽

Dominant Negative ◽

G1 Arrest ◽

Transactivation Domain ◽

Downstream Target ◽

Formyltetrahydrofolate Dehydrogenase ◽

Induced Apoptosis ◽

Hct116 Cells

A folate enzyme, FDH (10-formyltetrahydrofolate dehydrogenase; EC 1.5.1.6), is not a typical tumour suppressor, but it has two basic characteristics of one, i.e. it is down-regulated in tumours and its expression is selectively cytotoxic to cancer cells. We have recently shown that ectopic expression of FDH in A549 lung cancer cells induces G1 arrest and apoptosis that was accompanied by elevation of p53 and its downstream target, p21. It was not known, however, whether FDH-induced apoptosis is p53-dependent or not. In the present study, we report that FDH-induced suppressor effects are strictly p53-dependent in A549 cells. Both knockdown of p53 using an RNAi (RNA interference) approach and disabling of p53 function by dominant-negative inhibition with R175H mutant p53 prevented FDH-induced cytotoxicity in these cells. Ablation of the FDH-suppressor effect is associated with an inability to activate apoptosis in the absence of functional p53. We have also shown that FDH elevation results in p53 phosphorylation at Ser-6 and Ser-20 in the p53 transactivation domain, and Ser-392 in the C-terminal domain, but only Ser-6 is strictly required to mediate FDH effects. Also, translocation of p53 to the nuclei and expression of the pro-apoptotic protein PUMA (Bcl2 binding component 3) was observed after induction of FDH expression. Elevation of FDH in p53 functional HCT116 cells induced strong growth inhibition, while growth of p53-deficient HCT116 cells was unaffected. This implies that activation of p53-dependent pathways is a general downstream mechanism in response to induction of FDH expression in p53 functional cancer cells.

Download Full-text

Phloretin-induced Apoptosis in B16 Melanoma 4A5 Cells and HL60 Human Leukemia Cells

Bioscience Biotechnology and Biochemistry ◽

10.1271/bbb.63.719 ◽

1999 ◽

Vol 63 (4) ◽

pp. 719-725 ◽

Cited By ~ 50

Author(s):

Masuko KOBORI ◽

Keiko IWASHITA ◽

Hiroshi SHINMOTO ◽

Tojiro TSUSHIDA

Keyword(s):

B16 Melanoma ◽

Leukemia Cells ◽

Human Leukemia ◽

Human Leukemia Cells ◽

Induced Apoptosis

Download Full-text

Mechanism of patulin-induced apoptosis in human leukemia cells (HL-60)

Toxicology Letters ◽

10.1016/j.toxlet.2008.09.018 ◽

2008 ◽

Vol 183 (1-3) ◽

pp. 105-111 ◽

Cited By ~ 54

Author(s):

T WU ◽

Y LIAO ◽

F YU ◽

C CHANG ◽

B LIU

Keyword(s):

Leukemia Cells ◽

Human Leukemia ◽

Human Leukemia Cells ◽

Induced Apoptosis

Download Full-text

β2-Microglobulin induces apoptosis in CCRF-HSB-2 leukemia cells by molecular mechanisms different than doxorubicin- and Taxol-induced apoptosis mechanisms

European Journal of Cancer ◽

10.1016/s0959-8049(02)81216-3 ◽

2002 ◽

Vol 38 ◽

pp. S167

Keyword(s):

Molecular Mechanisms ◽

Leukemia Cells ◽

Β2 Microglobulin ◽

Induced Apoptosis

Download Full-text

Ectopic expression of homeotic genes caused by the elimination of the Polycomb gene in Drosophila imaginal epidermis

Development ◽

10.1242/dev.104.4.713 ◽

1988 ◽

Vol 104 (4) ◽

pp. 713-720 ◽

Cited By ~ 19

Author(s):

A. Busturia ◽

G. Morata

Keyword(s):

Ectopic Expression ◽

Homeotic Genes ◽

Sex Combs Reduced ◽

Hierarchical Order ◽

Sex Combs ◽

Morphological Patterns

The morphological patterns in the adult cuticle of Drosophila are determined principally by the homeotic genes of the bithorax and Antennapedia complexes. We find that many of these genes become indiscriminately active in the adult epidermis when the Pc gene is eliminated. By using the Pc3 mutation and various BX-C mutant combinations, we have generated clones of imaginal cells possessing different combinations of active homeotic genes. We find that, in the absence of BX-C genes, Pc- clones develop prothoracic patterns; this is probably due to the activity of Sex combs reduced which overrules Antennapedia. Adding contributions of Ultrabithorax, abdominal-A and Abdominal-B results in thoracic or abdominal patterns. We have established a hierarchical order among these genes: Antp less than Scr less than Ubx less than abd-A less than Abd-B. In addition, we show that the engrailed gene is ectopically active in Pc- imaginal cells.

Download Full-text