Phorbol ester–induced PKCϵ down-modulation sensitizes AML cells to TRAIL-induced apoptosis and cell differentiation

Blood ◽  
2009 ◽  
Vol 113 (13) ◽  
pp. 3080-3087 ◽  
Author(s):  
Giuliana Gobbi ◽  
Prisco Mirandola ◽  
Cecilia Carubbi ◽  
Cristina Micheloni ◽  
Chiara Malinverno ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Phorbol Ester ◽  
Phorbol Esters ◽  
Surface Expression ◽  
Low Concentrations ◽  
Differentiating Agents ◽  
Receptor Surface Expression ◽  
Induced Apoptosis ◽  
Necrosis Factor ◽  
Made In

AbstractDespite the relevant therapeutic progresses made in these last 2 decades, the prognosis of acute myeloid leukemia (AML) remains poor. Phorbol esters are used at very low concentrations as differentiating agents in the therapy of myeloid leukemias. Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL), in turn, is a death ligand that spares normal cells and is therefore currently under clinical trials for cancer therapy. Emerging evidence, however, suggests that TRAIL is also involved in nonapoptotic functions, like cell differentiation. PKCϵ is differentially modulated along normal hematopoiesis, and its levels modulate the response of hematopoietic precursors to TRAIL. Here, we investigated the effects of the combination of phorbol esters (phorbol ester 4-β-phorbol-12,13-dibutyrate [PDBu]) and TRAIL in the survival/differentiation of AML cells. We demonstrate here that PDBu sensitizes primary AML cells to both the apoptogenic and the differentiative effects of TRAIL via PKCϵ down-modulation, without affecting TRAIL receptor surface expression. We believe that the use of TRAIL in combination with phorbol esters (or possibly more specific PKCϵ down-modulators) might represent a significative improvement of our therapeutic arsenal against AML.

scholarly journals NF-κB Inducers Upregulate cFLIP, a Cycloheximide-Sensitive Inhibitor of Death Receptor Signaling

2001 ◽  
Vol 21 (12) ◽  
pp. 3964-3973 ◽  
Author(s):  
Sebastian Kreuz ◽  
Daniela Siegmund ◽  
Peter Scheurich ◽  
Harald Wajant
Keyword(s):  
Cell Lines ◽  
Death Receptor ◽  
Jurkat Cells ◽  
Negative Regulator ◽  
Inhibitory Protein ◽  
Iκb Kinase ◽  
Low Concentrations ◽  
Death Receptor Signaling ◽  
Induced Apoptosis ◽  
Necrosis Factor

ABSTRACT The caspase 8 homologue FLICE-inhibitory protein (cFLIP) is a potent negative regulator of death receptor-induced apoptosis. We found that cFLIP can be upregulated in some cell lines under critical involvement of the NF-κB pathway, but NF-κB activation was clearly not sufficient for cFLIP induction in all cell lines. Treatment of SV80 cells with the proteasome inhibitor N-benzoyloxycarbonyl (Z)-Leu-Leu-leucinal (MG-132) or geldanamycin, a drug interfering with tumor necrosis factor (TNF)-induced NF-κB activation, inhibited TNF-induced upregulation of cFLIP. Overexpression of a nondegradable IκBα mutant (IκBα-SR) or lack of IκB kinase γ expression completely prevented phorbol myristate acetate-induced upregulation of cFLIP mRNA in Jurkat cells. These data point to an important role for NF-κB in the regulation of the cFLIP gene. SV80 cells normally show resistance to TNF-related apoptosis-inducing ligand (TRAIL) and TNF, as apoptosis can be induced only in the presence of low concentrations of cycloheximide (CHX). However, overexpression of IκBα-SR rendered SV80 cells sensitive to TRAIL-induced apoptosis in the absence of CHX, and cFLIP expression was able to reverse the proapoptotic effect of NF-κB inhibition. Western blot analysis further revealed that cFLIP, but not TRAF1, A20, and cIAP2, expression levels rapidly decrease upon CHX treatment. In conclusion, these data suggest a key role for cFLIP in the antiapoptotic response of NF-κB activation.

scholarly journals RasGRP1 stimulation enhances ubiquitination and endocytosis of the sodium-chloride cotransporter

2010 ◽  
Vol 299 (2) ◽  
pp. F300-F309 ◽  
Author(s):  
Benjamin Ko ◽  
Erik-Jan Kamsteeg ◽  
Leslie L. Cooke ◽  
Lauren N. Moddes ◽  
Peter M. T. Deen ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Cell Surface ◽  
Phorbol Ester ◽  
Phorbol Esters ◽  
Surface Expression ◽  
Dominant Negative ◽  
Cell Surface Expression ◽  
Activity Regulation ◽  
Sodium Chloride Cotransporter ◽  
Radiotracer Uptake

The sodium-chloride cotransporter (NCC) is the principal salt-absorptive pathway in the distal convoluted tubule. Recently, we described a novel pathway of NCC regulation in which phorbol esters (PE) stimulate Ras guanyl-releasing protein 1 (RasGRP1), triggering a cascade ultimately activating ERK1/2 MAPK and decreasing NCC cell surface expression (Ko B, Joshi LM, Cooke LL, Vazquez N, Musch MW, Hebert SC, Gamba G, Hoover RS. Proc Natl Acad Sci USA 104: 20120–20125, 2007). Little is known about the mechanisms which underlie these effects on NCC activity. Regulation of NCC via changes in NCC surface expression has been reported, but endocytosis of NCC has not been demonstrated. In this study, utilizing biotinylation, internalization assays, and a dynamin dominant-negative construct, we demonstrate that the regulation of NCC by PE occurs via an enhancement in internalization of NCC and is dynamin dependent. In addition, immunoprecipitation of NCC and subsequent immunoblotting for ubiquitin showed increased ubiquitination of NCC with phorbol ester treatment. MEK1/2 inhibitors and gene silencing of RasGRP1 indicated that this effect was dependent on RasGRP1 and ERK1/2 activation. Inhibition of ubiquitination prevents any PE-mediated decrease in NCC surface expression as measured by biotinylation or NCC activity as measured by radiotracer uptake. These findings confirmed that the PE effect on NCC is mediated by endocytosis of NCC. Furthermore, ubiquitination of NCC is essential for this process and this ubiquitination is dependent upon RasGRP1-mediated ERK1/2 activation.

Ionizing radiation sensitizes erythroleukemic cells but not normal erythroblasts to tumor necrosis factor–related apoptosis-inducing ligand (TRAIL)–mediated cytotoxicity by selective up-regulation of TRAIL-R1

Blood ◽  
2001 ◽  
Vol 97 (9) ◽  
pp. 2596-2603 ◽  
Author(s):  
Roberta Di Pietro ◽  
Paola Secchiero ◽  
Rosalba Rana ◽  
Davide Gibellini ◽  
Giuseppe Visani ◽  
...  
Keyword(s):  
Tumor Necrosis Factor ◽  
Ionizing Radiation ◽  
Tumor Necrosis ◽  
K562 Cells ◽  
Surface Expression ◽  
Additive Effect ◽  
High Dose ◽  
Induced Apoptosis ◽  
Necrosis Factor ◽  
Erythroleukemic Cells

Abstract Cytotoxic activity of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL/Apo-2 ligand), used alone or in different combinations with either a low (1.5 Gy) or a high (15 Gy) single dose of ionizing radiation (IR), was investigated on erythroleukemic cells (K562, HEL, Friend, primary leukemic erythroblasts) and on primary CD34+-derived normal erythroblasts. Human recombinant TRAIL alone variably affected the survival/growth of erythroleukemic cells; K562 cells were the most sensitive. Moreover, all erythroleukemic cells were radio-resistant, as demonstrated by the fact that cytotoxicity was evident only after treatment with high-dose (15 Gy) IR. Remarkably, when IR and TRAIL were used in combination, an additive effect was noticed in all erythroleukemic cells. Augmentation of TRAIL-induced cell death by IR was observed with both low and high IR doses and required the sequential treatment of IR 3 to 6 hours before the addition of TRAIL. Conversely, both TRAIL and IR showed a moderate cytotoxicity on primary CD34+-derived normal erythroblasts when used alone, but their combination did not show any additive effect. Moreover, the cytotoxicity of IR plus TRAIL observed in erythroleukemic cells was accompanied by the selective up-regulation of the surface expression of TRAIL-R1 (DR4), and it was completely blocked by the z-Val-Ala-Asp (OMe)-CH2 (z-VAD-fmk) caspase inhibitor. On the other hand, the surface expression of TRAIL-R1 in CD34+-derived normal erythroblasts was unaffected by IR, which induced the up-regulation of the decoy TRAIL-R3. These data demonstrate that treatment with IR provides an approach to selectively sensitize erythroleukemic cells, but not normal erythroblasts, to TRAIL-induced apoptosis through the functional up-regulation of TRAIL-R1.

Induction of Monocytic Differentiation by Tumor Necrosis Factor in Phorbol Ester-resistant KG-1a Cells

1990 ◽  
Vol 2 (10) ◽  
pp. 327-332 ◽  
Author(s):  
Surender Kharbanda ◽  
Takashi Nakamura ◽  
Rakesh Datta ◽  
Matthew L. Sherman ◽  
Kufe Donald
Keyword(s):  
Tumor Necrosis Factor ◽  
Phorbol Ester ◽  
Tumor Necrosis ◽  
Monocytic Differentiation ◽  
Necrosis Factor

scholarly journals Inhibition of BCL11B induces downregulation of PTK7 and results in growth retardation and apoptosis in T-cell acute lymphoblastic leukemia

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Kehan Li ◽  
Cunte Chen ◽  
Rili Gao ◽  
Xibao Yu ◽  
Youxue Huang ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Growth Retardation ◽  
Lymphoblastic Leukemia ◽  
Downstream Target ◽  
B Cell Leukemia ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Induced Apoptosis ◽  
Necrosis Factor ◽  
Aggressive Subtype

AbstractT-cell acute lymphoblastic leukemia (T-ALL) is an aggressive subtype of leukemia with poor prognosis, and biomarkers and novel therapeutic targets are urgently needed for this disease. Our previous studies have found that inhibition of the B-cell leukemia/lymphoma 11B (BCL11B) gene could significantly promote the apoptosis and growth retardation of T-ALL cells, but the molecular mechanism underlying this effect remains unclear. This study intends to investigate genes downstream of BCL11B and further explore its function in T-ALL cells. We found that PTK7 was a potential downstream target of BCL11B in T-ALL. Compared with the healthy individuals (HIs), PTK7 was overexpressed in T-ALL cells, and BCL11B expression was positively correlated with PTK7 expression. Importantly, BCL11B knockdown reduced PTK7 expression in T-ALL cells. Similar to the effects of BCL11B silencing, downregulation of PTK7 inhibited cell proliferation and induced apoptosis in Molt-4 cells via up-regulating the expression of tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and p27. Altogether, our studies suggest that PTK7 is a potential downstream target of BCL11B, and downregulation of PTK7 expression via inhibition of the BCL11B pathway induces growth retardation and apoptosis in T-ALL cells.

Apoptosis in human cultured trophoblasts is enhanced by hypoxia and diminished by epidermal growth factor

2000 ◽  
Vol 278 (5) ◽  
pp. C982-C988 ◽  
Author(s):  
Roni Levy ◽  
Steven D. Smith ◽  
Kala Chandler ◽  
Yoel Sadovsky ◽  
D. Michael Nelson
Keyword(s):  
Cell Differentiation ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Fetal Growth ◽  
Fetal Growth Restriction ◽  
Caspase Inhibitor ◽  
Trophoblast Differentiation ◽  
Epidermal Growth ◽  
Induced Apoptosis

Preeclampsia and fetal growth restriction are associated with placental hypoperfusion and villous hypoxia. The villous response to this environment includes diminished trophoblast differentiation and enhanced apoptosis. We tested the hypothesis that hypoxia induces apoptosis in cultured trophoblasts, and that epidermal growth factor (EGF), an enhancer of trophoblast differentiation, diminishes hypoxia-induced apoptosis. Trophoblasts isolated from placentas of term-uncomplicated human pregnancies were cultured up to 72 h in standard ([Formula: see text]= 120 mmHg) or hypoxic ([Formula: see text] < 15 mmHg) conditions. Exposure to hypoxia for 24 h markedly enhanced trophoblast apoptosis as determined by DNA laddering, internucleosomal in situ DNA fragmentation, and histomorphology, as well as by the reversibility of the apoptotic process with a caspase inhibitor. Apoptosis was accompanied by increased expression of p53 and Bax and decreased expression of Bcl-2. Addition of EGF to cultured trophoblasts or exposure of more differentiated trophoblasts to hypoxia significantly lowered the level of apoptosis. We conclude that hypoxia enhances apoptosis in cultured trophoblasts by a mechanism that involves an increase in p53 and Bax expression. EGF and enhancement of cell differentiation protect against hypoxic-induced apoptosis.

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