scholarly journals Microenvironmental stromal cells abrogate NF-κB inhibitor-induced apoptosis in chronic lymphocytic leukemia

Haematologica ◽  
2017 ◽  
Vol 103 (1) ◽  
pp. 136-147 ◽  
Author(s):  
Carl Philipp Simon-Gabriel ◽  
Katharina Foerster ◽  
Shifa Saleem ◽  
Dorothee Bleckmann ◽  
Marco Benkisser-Petersen ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Stromal Cells ◽  
Lymphocytic Leukemia ◽  
Induced Apoptosis

Standardizing Co-Culture Conditions Between Chronic Lymphocytic Leukemia Cells and Marrow Stromal Cells: Towards a Reliable and Reproducible System to Assess Cell Adhesion-Mediated Drug Resistance

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3149-3149
Author(s):  
Antonina Kurtova ◽  
Maite P. Quiroga ◽  
William G. Wierda ◽  
Michael Keating ◽  
Jan A. Burger
Keyword(s):  
Bone Marrow ◽  
Drug Resistance ◽  
Cell Adhesion ◽  
Chronic Lymphocytic Leukemia ◽  
Stromal Cells ◽  
Lymphocytic Leukemia ◽  
Marrow Stromal Cells ◽  
Hpv E6 ◽  
Induced Apoptosis

Abstract Contact between chronic lymphocytic leukemia (CLL) cells and accessory stromal cells in tissue microenvironments is considered to play a major role in regulating CLL cell survival and disease progression. Stromal cells of various origins and species, and variable stromal-CLL cell ratios have been used in the past to study CLL-stromal cell interactions and to assess cell-adhesion mediated drug resistance (CAM-DR). Because of the heterogeneity of the currently used in vitro systems to study CLL-MSC interactions, and the importance of these co-culture systems for development and testing of novel agents, we tested a panel of murine and human MSC lines for their capacities to support CLL cell survival and CAM-DR, using various CLL-MSC ratios and fludarabine (F-ara-A) to induce CLL cell apoptosis. We tested four murine, non-transformed MSC lines derived from bone marrow: M210B4, KUM4, ST-2 and KUSA-H1. Also, we tested three human transformed cell lines: Stroma-NKtert, derived from bone marrow and immortalized by human telomerase reverse transcriptase (hTERT), UE6E7-T2 derived from bone marrow and transformed with human papilloma viruses (HPV) E6, E7 and hTERT, and UCB408E6E7Tert33 derived from umbilical cord blood and transformed with hTERT and HPV E6, E7. CLL cells were isolated from peripheral blood of untreated patients and each cell line was tested with at least three different patients according to the following protocol: viability of CLL was tested after 24, 48 and 72 hours by flow cytometry after staining with DiOC6 and propidium iodide. The following conditions were assayed on each of the MSC lines: CLL cells in suspension culture, CLL cells in suspension culture with 10 mM F-ara-A, CLL cells in co-culture with MSC, and CLL cells in co-culture with MSC and with 10 mM F-ara-A. Firstly, we performed titration experiments in order to identify the most appropriate ratio between stromal and CLL cells, using CLL-MSC ratios of 5:1, 10:1, 20:1, 50:1 and 100:1. We found a decline in MSC-derived CLL cell protection at the highest ratio of 100:1, suggesting that ratios of 50:1 or lower provide optimal conditions for in vitro assays. Results shown in Table 1 were assayed using a 20:1 ratio and represented relative viabilities when compared to untreated controls (mean±SEM). Regarding the protective effect of different MSC, we found that all MSC lines demonstrated remarkable protection of CLL cells from spontaneous and F-ara-A-induced apoptosis. We also found that stromal cells that had round shape morphology and easily formed confluent monolayer (M210B4, KUSA-H1, Stroma-NKTert) showed more prolonged protective effect in comparison to cell lines with more spindle shaped morphology (ST-2, KUM4, UE6E7-T2). The failure of UE6E7-T2 and UCB408E6E7Tert33 to demonstrate long-term protection of CLL cells could be related to their own sensitivity to F-ara-A. In this comparative study we demonstrated that both murine and human MSC provide substantial and comparable levels of protection from spontaneous and drug-induced apoptosis. CLL:MSC ratios of 50:1 or lower can be considered ideal for co-culture experiments. Further experiments have to be done to determine the levels of MSC-derived protection in a larger series of CLL samples and in different laboratories for validation. Collectively, in these co-culture assays we can study CLL-MSC interactions and CLL drugs under more standardized conditions that may allow us to evaluate the efficacy of new treatments that target the CLL microenvironment. Time points 24 hours 48 hours 72 hours +Flu + MSC + MSC +Flu +Flu + MSC + MSC +Flu +Flu +MSC + MSC +Flu M210B4 85.2±2.4 117.2±5.0 110.5±4.9 30.8±12.6 138.1±9.5 113.0±2.2 5.2±3.1 138.1±5.1 120.4±3.4 ST-2 93.6±3.0 99.9±2.6 103.1±0.5 51.6±9.4 111.9±2.6 89.8±8.7 13.9±6.3 112.6±5.7 87.0±16.4 KUM-4 93.6±3.0 106.4±1.8 104.2±1.9 51.6±9.4 112.4±2.6 100.8±2.8 13.9±6.3 111.8±6.7 88.5±11.4 KUSA-H1 79.4±7.4 125.1±3.7 118.2±2.0 33.9±10.9 136.0±3.6 107.2±7.0 11.3±6.1 133.6±5.4 84.9±7.6 Stroma-NKTert 79.3±7.0 118.6±7.0 111.0±7.0 30.5±9.5 130.7±9.5 115.6±8.0 7.1±4.3 133.0±11.5 122.7±9.0 UE6E7-T2 79.3±7.0 113.4±3.9 109.3±3.0 30.5±9.5 118.4±4.8 85.0±7.1 7.1±4.3 119.2±6.9 51.0±10.1 UCB408 E6E7Tert33 81.5±7.2 120.2±5.4 111.8±2.7 36.7±9.4 123.7±6.3 86.7±7.7 8.5±6.7 119.7±6.1 50.8±13.0 Table 1. Flu: fludarabine (10mM/ml), MSC: marrow stromal cells

scholarly journals Homoharringtonine reduced Mcl-1 expression and induced apoptosis in chronic lymphocytic leukemia

Blood ◽  
2011 ◽  
Vol 117 (1) ◽  
pp. 156-164 ◽  
Author(s):  
Rong Chen ◽  
Lei Guo ◽  
Yuling Chen ◽  
Yingjun Jiang ◽  
William G. Wierda ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Stromal Cells ◽  
Single Agent ◽  
Myeloid Cell ◽  
Lymphocytic Leukemia ◽  
Caspase Cleavage ◽  
Translation Inhibition ◽  
Transcription Inhibitor ◽  
Induced Apoptosis ◽  
Elongation Phase

Abstract Homoharringtonine (HHT) is a plant alkaloid that inhibits the elongation phase of translation that is currently in clinical trials. Because the intrinsically short-lived antiapoptotic protein myeloid cell leukemia-1 (Mcl-1) has been reported to support the survival of chronic lymphocytic leukemia (CLL) cells, we hypothesized that inhibition of protein synthesis by HHT would decrease Mcl-1 expression and induce apoptosis in CLL. In primary CLL cells, HHT induced significant apoptosis independent of the prognostic characteristics of the patients. This was associated with inhibition of translation and decreased Mcl-1 levels in CLL cells. Mcl-1 reduction was evident as early as 2 hours and continued to decrease in the next 6-8 hours, whereas cell death started in 2 hours and continued to increase for 24 hours. Reduction of the Mcl-1 level was due to translation inhibition and proteasome degradation rather than to transcription inhibition or caspase cleavage. HHT and the transcription inhibitor SNS-032 induced synergistic cell killing. Although stromal cells induced Mcl-1 expression and protected CLL cells from the toxicity of fludarabine, this induction was reversed by HHT, which overcame stromal cell–mediated protection. Thus, these results provide a rationale for clinical development of HHT in CLL as single agent or in combinations.

BMS-936564 (MDX1338): A Fully Human Anti-CXCR4 Antibody Induces Apoptosis in an in Vitro Model of Stromal – Leukemia Cell Interaction for Chronic Lymphocytic Leukemia.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2887-2887
Author(s):  
Manoj Kumar Kashyap ◽  
Deepak Kumar ◽  
Harrison Jones Jones ◽  
Michael Y. Choi ◽  
Johanna Melo-Cardenas ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Stromal Cells ◽  
Leukemia Cell ◽  
Cell Interaction ◽  
Lymphocytic Leukemia ◽  
Leukemia Cells ◽  
Drug Induced ◽  
Induced Apoptosis ◽  
Cells Cultured

Abstract Abstract 2887 Chronic lymphocytic leukemia (CLL) remains incurable despite advances in the biology and treatment of this disease. Current data support the notion that resistance to therapy is promoted by a “protective” tumor microenvironment in which non-leukemia cells produce factors that enhance the resistance of CLL cells to spontaneous or drug-induced apoptosis. One such factor is the chemokine CXCL12, which interacts with its receptor CXCR4 on CLL cells to promote cancer cell survival. To examine the therapeutic potential of blocking CXCL12-CXCR4 interactions, we studied the effect of BMS-936564, a fully human IgG4 anti-CXCR4 antibody, using an in vitro co-culture model of human bone marrow derived stomal-NKter cells – leukemia cell interaction. Such stromal-NKter cells secrete CXCL12 and enhance the resistance of CLL cells to apoptosis in vitro. We observed that primary CLL cells co-cultured with stromal-NKter cells had significantly greater viability than CLL cells cultured alone (20–60% above baseline at 48 hours). Moreover, CLL cells co-cultured with stromal cells had enhanced resistance to drug-induced apoptosis. We found that BMS-936564 antibody at concentrations of 2–200nM could enhance the rate of apoptosis of CLL cells cultured alone or in the presence of stromal cells. CLL cells that expressed unmutated IgVH genes or ZAP-70 appeared equally susceptible to treatment with BMS-936564 as did CLL cells that lack these adverse prognostic markers, as did CLL cells that harbored deletions in 17p13.2 and that were resistant to chemotherapeutic agents, such a fludarabine monophosphate. BMS-936564 antibody inhibited CXCL12 mediated F-Actin polymerization in CLL cells at lower concentrations (20–200nM) compared to AMD-3100 (Mozobil), a small molecule CXCR4 inhibitor (50–150μM). In addition, AMD-3100 did not induce apoptosis in CLL cells (10–300μM). In summary, we observed that the anti-CXCR4 antibody BMS-936564 inhibited CXCL12 mediated activation of the CXCR4 receptor in CLL cells and induced apoptosis in leukemia cells. The pro-apoptotic activity of BMS-936564 was observed in cells cultured alone or together with stromal cells suggesting that this antibody had direct cytotoxic effect on leukemia cells and that it can overcome the protective tumor microenvironment. More over, the activity of BMS-936564 was independent of the presence of poor prognostic factors such as del(17p) suggesting that its mechanism of action is P53 independent. These findings show evidence that the CXCR4-CXCL12 pathway is a valid therapeutic target in CLL and provide additional biological rationale for ongoing clinical trials in CLL and other hematological malignancies using BMS-936564. Disclosures: Kuhne: Bristol-Myers Squibb: Employment. Sabbatini:Bristol-Myers Squibb: Employment. Cohen:Bristol-Myers Squibb: Employment. Shelat:Bristol-Myers Squibb: Employment. Cardarelli:Bristol-Myers Squibb: Employment. Kipps:Abbott: Consultancy, Research Funding.

Small peptide inhibitors of the CXCR4 chemokine receptor (CD184) antagonize the activation, migration, and antiapoptotic responses of CXCL12 in chronic lymphocytic leukemia B cells

Blood ◽  
2005 ◽  
Vol 106 (5) ◽  
pp. 1824-1830 ◽  
Author(s):  
Meike Burger ◽  
Tanja Hartmann ◽  
Myriam Krome ◽  
Justyna Rawluk ◽  
Hirokazu Tamamura ◽  
...  
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Stromal Cells ◽  
Chemokine Receptors ◽  
Actin Polymerization ◽  
Leukemia Cell ◽  
Lymphocytic Leukemia ◽  
Mitogen Activated Protein Kinase ◽  
Cxcr4 Antagonists ◽  
Induced Apoptosis

Abstract Growth and survival of chronic lymphocytic leukemia (CLL) B cells are favored by interactions between CLL and nontumoral accessory cells. CLL cells express CXCR4 chemokine receptors that direct leukemia cell chemotaxis. Marrow stromal cells or nurselike cells constitutively secrete CXCL12, the ligand for CXCR4, thereby attracting and rescuing CLL B cells from apoptosis in a contact-dependent fashion. Therefore, the CXCR4-CXCL12 axis represents a potential therapeutic target in CLL. We evaluated the most active CXCR4-specific antagonists (T140, TC14012, TN14003) for their capacity to inhibit CXCL12 responses in CLL cells. T140, or its analogs, inhibited actin polymerization, chemotaxis, and migration of CLL cells beneath stromal cells. CXCL12-induced phosphorylation of p44/42 mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription 3 (STAT3) was abolished by CXCR4 antagonists. TC14012 and TN14003 antagonized the antiapoptotic effect of synthetic CXCL12 and stromal cell-mediated protection of CLL cells from spontaneous apoptosis. Furthermore, we found that stromal cells protected CLL cells from chemotherapy-induced apoptosis. Treatment with CXCR4 antagonists resensitized CLL cells cultured with stromal cells to fludarabine-induced apoptosis. These findings demonstrate that CXCR4 blocking agents effectively antagonize CXCL12-induced migratory and signaling responses and stromal protection of CLL cells from spontaneous or fludarabine-induced apoptosis. As such, small molecular CXCR4 antagonists may have activity in the treatment of patients with this disease. (Blood. 2005;106:1824-1830)

Importance of PI3 Kinase Family for Crosstalk between Chronic Lymphocytic Leukemia B Cells and the Stromal Microenvironment: Therapeutic Implications.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1125-1125
Author(s):  
Matthias T.W. Niedermeier ◽  
Justyna Rawluk ◽  
Zachary Knight ◽  
Kevan Shokat ◽  
William G. Wierda ◽  
...  
Keyword(s):  
Cell Migration ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Stromal Cells ◽  
Therapeutic Potential ◽  
Dominant Role ◽  
Lymphocytic Leukemia ◽  
Drug Induced ◽  
Cxcr4 Signaling ◽  
Induced Apoptosis

Abstract Nontumoral accessory cells such as marrow stromal cells (MSC) or nurselike cells (NLC), which constitute the leukemia microenvironment, constitutively secrete the chemokine stromal cell-derived factor-1 (SDF-1/CXCL12). CXCL12 transduces signals via its receptor CXCR4, which is expressed at high levels by Chronic Lymphocytic Leukemia (CLL) B cells. Via the CXCL12-CXCR4 axis, CLL cells migrate and adhere to stromal cells. Adhesion to stromal cells protects CLL cells from spontaneous and drug-induced apoptosis in a contact-dependent fashion. Signaling pathways regulating these processes in CLL B cells are largely unknown. Here, we examined the importance of phosphatidyl-inositide 3-kinases (PI3-K) for migration and viability of CLL B cells using non-specific and isoform-specific PI3-K inhibitors. The importance of PI3-K for migration of CLL cells to CXCL12 was determined by transwell chemotaxis and pseudoemperipolesis (PEP) assays. Inhibition of PI3-K resulted in a significant reduction of CLL cell migration in chemotaxis and PEP assays. In comparison to untreated CLL cells, Ly 294002 inhibited chemotaxis to 65 ± 4.6% of untreated controls. Using a panel of isoform-specific PI 3-K inhibitors (PI-103, PIK-90, IC87114, TGX-115, ZK-75), we observed inhibition of chemotaxis by the multi-targeted compounds PI-103 (51.4 ± 0.2%) and PIK-90 (57.5 ± 8.9%), whereas p110beta and delta inhibition had no effect. We conclude from this part of the study that PI3-kinases play an important role for CXCR4 signaling in CLL B cells, mediating migratory responses and protection from apoptosis. Experiments with inhibitors of PI3-K with higher target selectivity suggest a dominant role for the class I PI3-K p110alpha for migration in response to CXCL12. Because adhesion to stroma mediates protection from chemotherapeutic drugs, we tested PI3-K inhibitors alone and in combination with fludarabine in CLL-stroma co-cultures. Pre-treatment of CLL cells with the PI3-K inhibitors Ly 294002, PI-103, and PIK-90 resulted in a significant decrease in viability of CLL cells co-cultured with and without stroma. Moreover, PI3-K isoform specific inhibitors enhance the cytotoxicity of Fludarabine and partially reverse the protective effect of stromal cells on fludarabine-induced apoptosis. Collectively, this study establishes that PI3-Ks play an important role in CXCR4 signaling for CLL cell migration and adhesion to stromal cells. New, isoform-specific PI3-K inhibitors enhance the cytotoxicity of fludarabine in suspension cultures and in co-cultures with stromal cells. Therefore, the therapeutic potential of PI3-K inhibitors alone or in combination with fludarabine should further be investigated. Figure. Figure.

scholarly journals Akt Inhibitors Induce Apoptosis in Chronic Lymphocytic Leukemia Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1731-1731
Author(s):  
Mercè de Frias ◽  
Daniel Iglesias-Serret ◽  
Ana M Cosialls ◽  
Llorenç Coll-Mulet ◽  
Antonio F Santidrián ◽  
...  
Keyword(s):  
T Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Conflicts Of Interest ◽  
Therapeutic Option ◽  
Mrna Level ◽  
Lymphocytic Leukemia ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Healthy Donors ◽  
Induced Apoptosis

Abstract Abstract 1731 Poster Board I-757 Phosphatidylinositol-3-kinase (PI3K)/Akt pathway has been described to be critical in the survival of chronic lymphocytic leukemia (CLL) cells. Here, we have analyzed the effect of two selective chemical inhibitors of Akt (Akti-1/2 and A-443654) in the survival of CLL cells. We studied by cytometric analysis the cytotoxic effects of Akt inhibitors on peripheral B and T lymphocytes from patients with CLL and from healthy donors. Both inhibitors induced apoptosis in CLL cells in a dose-dependent manner. Moreover, B cells from CLL samples were more sensitive to Akt inhibitors than T cells from CLL samples, and B or T cells from healthy donors. Survival factors for CLL cells, such as IL-4 and SDF-1a, were not able to block the apoptosis induced by both Akt inhibitors. We studied the changes induced by Akti-1/2 and A-443654 at mRNA level by performing reverse transcriptase multiplex ligation–dependent probe amplification (RT-MLPA). Akti-1/2 did not induce any change in the mRNA expression profile of genes involved in apoptosis, while A-443654 induced some changes, including an increase in NOXA and PUMA mRNA levels, suggesting the existence of additional targets for A-443654. We also studied the changes induced by both Akt inhibitors in some BCL-2 protein family members on CLL cells by Western blot. Both inhibitors induced an increase in PUMA and NOXA protein levels, and a decrease in MCL-1 protein level. Moreover, Akti-1/2 and A-443654 induced apoptosis irrespective of TP53 status. These results demonstrate that Akt inhibitors induce apoptosis of CLL cells and might be a new therapeutic option for the treatment of CLL. Disclosures No relevant conflicts of interest to declare.

Triggering of CD40 Antigen Inhibits Fludarabine-Induced Apoptosis in B Chronic Lymphocytic Leukemia Cells

Blood ◽  
1998 ◽  
Vol 92 (3) ◽  
pp. 990-995 ◽  
Author(s):  
Maria Fiammetta Romano ◽  
Annalisa Lamberti ◽  
Pierfrancesco Tassone ◽  
Fiorella Alfinito ◽  
Silvia Costantini ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Consensus Sequence ◽  
Significant Proportion ◽  
Lymphocytic Leukemia ◽  
Antiapoptotic Effect ◽  
Apoptotic Effect ◽  
American Society ◽  
Induced Apoptosis ◽  
Decoy Oligonucleotide

Abstract We analyzed the effect of CD40 triggering on the fludarabine-induced apoptosis of B chronic lymphocytic leukemia (B-CLL) cells. Peripheral blood samples obtained from 15 patients were incubated with fludarabine in the absence or the presence of the anti-CD40 monoclonal antibody (MoAb) G28-5. In 12 patients a significant proportion of apoptotic cells, ranging from 22% to 38% (mean ± SE: 28.5 ± 1.6), were detected after 3 days of culture. In 9 of these samples, the addition of G28-5 reduced apoptosis by at least 30.1% and by 57.1% ± 7.8% on average (P = .0077). Because the CD40 antigen activates NF-κB/Rel transcription factors in B cells, and NF-κB/Rel complexes can inhibit cell apoptosis, we investigated whether the antiapoptotic effect of G28-5, in our system, could be related to modulation of NF-κB/Rel activity. As expected, B-CLL cells displayed significant levels of nuclear NF-κB/Rel activity; p50, RelA, and c-Rel components of the NF-κB/Rel protein family were identified in these complexes. After exposure to fludarabine, NF-κB/Rel complexes were decreased in the nuclei. The addition of G28-5 upregulated the NF-κB/Rel levels. To determine the involvement of NF-κB/Rel activity in the G28-5–mediated inhibition of apoptosis, we blocked the transcription factor with a decoy oligonucleotide, corresponding to the NF-κB/Rel consensus sequence. Cells incubated with the anti-CD40 MoAb in the presence of the decoy oligonucleotide but not a control oligonucleotide displayed a complete impairment of the G28-5 antiapoptotic effect, indicating that NF-κB/Rel activity was required for the inhibition of apoptosis. These results suggest that CD40 triggering in vivo could counteract the apoptotic effect of fludarabine on B-CLL cells and that its neutralization, or the use of NF-κB/Rel inhibitors, could improve the therapeutic effect of fludarabine. © 1998 by The American Society of Hematology.

Theophylline synergizes with chlorambucil in inducing apoptosis of B- chronic lymphocytic leukemia cells

Blood ◽  
1996 ◽  
Vol 88 (6) ◽  
pp. 2172-2182 ◽  
Author(s):  
F Mentz ◽  
MD Mossalayi ◽  
F Ouaaz ◽  
S Baudet ◽  
F Issaly ◽  
...  
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Apoptotic Cell ◽  
Protein A ◽  
Phosphodiesterase Inhibitor ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Lymphocytic Leukemia ◽  
Interleukin 4 ◽  
Induced Apoptosis

We tested the effects of theophylline, a phosphodiesterase inhibitor inducing intracellular accumulation of cyclic adenosine monophosphate (cAMP), on malignant B cells from 15 patients with B-chronic lymphocytic leukemia (B-CLL). We observed a large increase in apoptotic cell numbers (mean, 90% v 20% in medium alone) in the presence of theophylline (100 micrograms/mL) or chlorambucil (10 mumol/L) after 72 hours of incubation. Maximal apoptosis (90%) was reached after 36 hours when the two drugs were used together at fourfold lower concentrations, indicating a synergistic effect; no effect was observed with normal B cells, suggesting that the combination might have therapeutic interest. Chlorambucil induced intracellular Ca+2 influx, pointing to the involvement of two signaling pathways that might explain its synergy with theophylline through their effects on oncogenes. The expression of bcl-2 protein, a proto-oncogene inhibiting apoptosis, decreased after incubation with the drugs, while c-myc, recently described as having a potent role in apoptosis, was overexpressed. For p53 we observed an overexpression in the presence of chlorambucil or both theophylline- chlorambucil and a decrease after theophylline incubation. Chlorambucil- and theophylline-induced apoptosis was partially inhibited by interleukin-4 (IL-4), which also abrogated the effects on oncogene expression. These results provide insight into the mechanisms underlying B-CLL apoptosis and suggest that the theophylline- chlorambucil combination may be of therapeutic value in this setting.

Reconstitution of PTEN activity by CK2 inhibitors and interference with the PI3-K/Akt cascade counteract the antiapoptotic effect of human stromal cells in chronic lymphocytic leukemia

Blood ◽  
2010 ◽  
Vol 116 (14) ◽  
pp. 2513-2521 ◽  
Author(s):  
Medhat Shehata ◽  
Susanne Schnabl ◽  
Dita Demirtas ◽  
Martin Hilgarth ◽  
Rainer Hubmann ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Chronic Lymphocytic Leukemia ◽  
Stromal Cells ◽  
Molecular Mechanisms ◽  
Mononuclear Cells ◽  
Lymphocytic Leukemia ◽  
Therapeutic Concept ◽  
Antiapoptotic Effect ◽  
Human Stromal Cells ◽  
Ck2 Inhibitors

Abstract Evidence suggests that tumor microenvironment is critically involved in supporting survival of chronic lymphocytic leukemia (CLL) cells. However, the molecular mechanisms of this effect and the clinical significance are not fully understood. We applied a microenvironment model to explore the interaction between CLL cells and stromal cells and to elucidate the role of phosphatidylinositol 3 kinase (PI3-K)/Akt/phosphatase and tensin homolog detected on chromosome 10 (PTEN) cascade in this process and its in vivo relevance. Primary human stromal cells from bone marrow, lymph nodes, and spleen significantly inhibited spontaneous apoptosis of CLL cells. Pan–PI3-K inhibitors (LY294002, wortmannin, PI-103), isotype-specific inhibitors of p110α, p110β, p110γ, and small interfering RNA against PI3-K and Akt1 counteracted the antiapoptotic effect of the stromal cells. Induction of apoptosis was associated with a decrease in phosphatidylinositol-3,4,5-triphosphate, PI3-K–p85, and dephosphorylation of phosphatidylinositol-dependent kinase-1 (PDK-1), Akt1, and PTEN. Freshly isolated peripheral blood mononuclear cells from patients with CLL (n = 44) showed significantly higher levels of phosphorylated Akt1, PDK-1, PTEN, and CK2 than healthy persons (n = 8). CK2 inhibitors (4,5,6,7-tetrabromo-1H-benzotriazole, apigenin, and 5,6-dichloro-1-β-D-ribofuranosylbenzimidazol) decreased phosphorylation of PTEN and Akt, induced apoptosis in CLL cells, and enhanced the response to fludarabine. In conclusion, bone marrow microenvironment modulates the PI3-K/Akt/PTEN cascade and prevents apoptosis of CLL cells. Combined inhibition of PI3-K/Akt and recovery of PTEN activity may represent a novel therapeutic concept for CLL.

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