In Vitro Activity of a Novel Fully Human Anti-CD40 Antibody CHIR-12.12 in Chronic Lymphocytic Leukemia: Blockade of CD40 Activation and Induction of ADCC.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2504-2504 ◽  
Author(s):  
Xia Tong ◽  
Georgios V. Georgakis ◽  
Long Li ◽  
O’Brien Susan ◽  
Younes Anas ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Cell Death ◽  
Chronic Lymphocytic Leukemia ◽  
Cell Line ◽  
Blood Donors ◽  
Lymphocytic Leukemia ◽  
Dependent Manner ◽  
Dose Dependent

Abstract B-cell chronic lymphocytic leukemia (CLL) is characterized by in vivo accumulation of long-lived CD5+ B cells. However when cultured in vitro CLL cells die quickly by apoptosis. Protection from apoptosis in vivo is believed to result from supply of survival signals provided by cells in the microenvironment. We and others have previously reported that CLL cells express CD40 receptor, and that CD40 stimulation of CLL cells may rescue CLL cells from spontaneous and drug-induced apoptosis in vitro. These observations suggested that blocking CD40-CD40L pathway might deprive CLL cells from survival signals and induce apoptosis. To test this hypothesis, we have generated a fully human anti-CD40 blocking monoclonal antibody in XenoMousemice (Abgenix, Inc.). The antibody CHIR-12.12 was first evaluated for its effect on normal human lymphocytes. Lymphocytes from all 10 healthy blood donors did not proliferate in response to CHIR-12.12 at any concentration tested (0.0001 mg/ml to 10 mg/ml range). In contrast, activating CD40 on normal B-lymphocytes by CD40L induced their proliferation in vitro. Importantly, CHIR-12.12 inhibited CD40L- induced proliferation in a dose dependent manner with an average IC50 of 51 ± 26 pM (n=10 blood donors). The antagonistic activity of CHIR-12.12 was then tested in primary CLL samples from 9 patients. CHIR-12.12 alone did not induce CLL cell proliferation. In contrast, primary CLL cells incubated with CD40L, either resisted spontaneous cell death or proliferated. This effect was reversed by co-incubation with CHIR-12.12 antibody, restoring CLL cell death (n=9). CHIR-12.12 was then examined for its ability to lyse CLL cell line EHEB by antibody dependent cell mediated cytotoxicity (ADCC). Freshly isolated human NK cells from normal volunteer blood donors were used as effector cells. CHIR-12.12 showed lysis activity in a dose dependent manner and produced maximum lysis levels at 0.1 mg/ml. When compared with rituximab, CHIR-12.12 mediated greater maximum specific lysis (27.2 % Vs 16.2 %, p= 0.007). The greater ADCC by CHIR-12.12 was not due to higher density of CD40 molecules on CLL cell line compared to CD20 molecules. The CLL target cells expressed 509053 ±13560 CD20 molecules compared to 48416 ± 584 CD40 molecules. Collectively, these preclinical data suggest that CHIR-12.12 monoclonal antibody may have a therapeutic role in patients with CLL.

scholarly journals TB-4 Antitumor effects of a novel curcumin derivative curcumin monoglucuronide on glioblastoma cells in vitro and in vivo

2021 ◽  
Vol 3 (Supplement_6) ◽  
pp. vi6-vi6
Author(s):  
Takashi Fujii ◽  
Shun Yamamuro ◽  
Masamichi Takahashi ◽  
Akihide Kondo ◽  
Yoshitaka Narita ◽  
...  
Keyword(s):  
Cell Death ◽  
Water Soluble ◽  
Dependent Manner ◽  
Antitumor Effects ◽  
Multiple Cell ◽  
Human Gbm ◽  
Dose Dependent ◽  
Novel Therapeutic

Abstract The therapeutic outcome of glioblastomas (GBMs) is still very poor. Therefore, invention of novel therapeutic methods against GBM cases is considered urgent. The antitumor effects of naturally-derived compounds are attracting attention recently, and therapeutic efficacy of curcumin, a plant-derived compound previously used for multiple purpose, has been indicated in many cancer systems; however, clinical application of curcumin is considered difficult because of its poor bioavailability (under 1 %). Curcumin monoglucuronide (CMG), a water-soluble prodrug of curcumin recently developed for overcoming this weakness, has been demonstrated excellent antitumor effects for several malignancies in vitro and in vivo; therefore, we investigated the effects of CMG against GBM cells. CMG induced cell death of human GBM cells lines (T98G, U251MG, and U87MG) by dose dependent manner by triggering multiple forms of cell death such as apoptosis and perthanatos. Immunoblotting of CMG-treated GBM cell lysates demonstrated activation of multiple cell death signaling. Furthermore, immunodeficiency mice harboring intracerebral U87MG cell xenografts systemically treated by CMG showed significantly prolonged survival compared with control mice. These results suggest CMG would be a novel therapeutic agent against GBM cases.

scholarly journals Involvement of CED-3/ICE Proteases in the Apoptosis of B-Chronic Lymphocytic Leukemia Cells

Blood ◽  
1997 ◽  
Vol 89 (9) ◽  
pp. 3378-3384 ◽  
Author(s):  
Beatriz Bellosillo ◽  
Mireia Dalmau ◽  
Dolors Colomer ◽  
Joan Gil
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Lymphocytic Leukemia ◽  
Interleukin 4 ◽  
Leukemia Cells ◽  
Parp Cleavage ◽  
Dependent Manner ◽  
Kinase C ◽  
Dose Dependent ◽  
Pkc Activation

Abstract B-chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of long-lived B lymphocytes that express high levels of Bcl-2. We examined the involvement of CED-3/ICE-like proteases in the apoptosis of B-CLL cells. One of the substrates of these proteases is poly(ADP [adenosine 5′-diphosphate]-ribose) polymerase (PARP). The effect of different factors that induce the apoptosis of B-CLL cells on the proteolytic cleavage of PARP has been studied. Treatment of B-CLL cells with different concentrations of dexamethasone (1 to 1,000 μmol/L) induced in a dose-dependent manner the cleavage of PARP. Dexamethasone induced PARP cleavage after 12 hours of incubation, which was almost complete at 48 hours. PARP cleavage during apoptosis of B-CLL cells was studied in cells from eight patients and a correlation was found between cell viability and the degree of PARP cleavage. Incubation in vitro of B-CLL cells with fludarabine for 48 hours induced PARP cleavage in all the cases studied. Protein kinase C (PKC) activation with 100 nmol/L TPA (12-O-tetradecanoylphorbol 13-acetate) or incubation with interleukin-4 (10 ng/mL) prevented either dexamethasone- or fludarabine-induced proteolysis of PARP. Incubation of B-CLL cells with the CED-3/ICE–like protease inhibitor Z-VAD.fmk inhibited spontaneous and dexamethasone-induced PARP cleavage and DNA fragmentation in a dose-dependent manner. Furthermore, Z-VAD.fmk prevented the cytotoxic effect of dexamethasone. These results indicate that CED-3/ICE–like proteases play an important role in the apoptosis of B-CLL cells.

scholarly journals Four ricin chain A-based immunotoxins directed against the common chronic lymphocytic leukemia antigen: in vitro characterization

Blood ◽  
1993 ◽  
Vol 82 (2) ◽  
pp. 536-543
Author(s):  
GB Faguet ◽  
JF Agee
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
T Lymphocytes ◽  
Ex Vivo ◽  
Lymphocytic Leukemia ◽  
Fab Fragment ◽  
In Vitro Characterization ◽  
The Common ◽  
Dose Dependent

The common B-chronic lymphocytic leukemia (B-CLL) antigen (cCLLa) appears to be ideal for targeted immunotherapy in that it is the most prevalent and disease-restricted marker in B-CLL. To assess this potential, we developed four immunotoxins (ITs) of anti-cCLLa monoclonal antibody CLL2m (an IgG2a kappa), using ricin chain A (RTA) or its deglycosylated derivative (dgA), each conjugated to either the whole IgG molecule or its Fab' fragment. Each IT was tested in vitro for specificity and cytotoxic activity (assessed by protein synthesis inhibition [PSI] and by cell kill [CK] in the clonogenic assay) against B-CLL cells. RTA-based anti-CD5 ITs and enriched normal B and T lymphocytes were used as controls. Each IT exhibited antigen-specific, dose-dependent activity. Thus, whereas B-CLL cells exhibited dose- dependent PSI and CK (whether the B-CLL clone was CD5+ or CD5-), normal B (cCLLa-/CD5-) and T lymphocytes (cCLLa-/CD5+) remained unaffected. IT potency was independent of toxin glycosylation, but was slightly influenced by antibody valence; divalent ITs were twice as potent as monovalent ITs (IC50, 2.3 v 7.1 x 10(-11) mol/L; CK, 2.6- v 2.0-log reached with 524 v 1,072 IT molecules bound/cell, respectively). In the presence of ammonium chloride or Verapamil, IT-induced CK was enhanced 10- to 80-fold. These data suggest that the cCLLa is a promising target for IT-based immunotherapy of B-CLL in vivo and ex vivo.

A Fibrin Specific Monoclonal Antibody which Interferes with the Fibrinolytic Effect of Tissue Plasminogen Activator

1988 ◽  
Vol 59 (03) ◽  
pp. 426-431 ◽  
Author(s):  
P E Gargan ◽  
V A Ploplis ◽  
J D Scheu
Keyword(s):  
Monoclonal Antibody ◽  
Cell Line ◽  
Specific Antibody ◽  
Myeloma Cell ◽  
Dependent Manner ◽  
Mouse Myeloma Cell Line ◽  
Release Assay ◽  
Dose Dependent ◽  
Mouse Myeloma

SummaryMonoclonal antibodies to human fibrin have been prepared from stable hybridomas, obtained by fusion of a mouse myeloma cell line (NS-1) and spleen cells of Balb/c mice immunized with a suspension of human fibrin. One cell line, DG1, producing a monoclonal antibody of the IgG1 κ subclass, reacted specifically with human fibrin (KD = 1.2 nM). Western blotting analysis indicates that DG1 crossreacts with the fibrin fragment D-dimer. Using both a chromogenic and an 125I-fibrin release assay it was illustrated that in the presence of the fibrin specific antibody the t-PA mediated generation of plasmin was significantly inhibited.An animal model system, developed to monitor thrombosis and induced reactive fibrinolysis, was used to investigate the interference of plasminogen activation, by the antibody, in vivo.This fibrin specific antibody prolonged the onset of reactive fibrinolysis in a dose dependent manner.

scholarly journals Docosahexaenoic acid induces apoptosis in primary chronic lymphocytic leukemia cells

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Romain Guièze ◽  
Emmanuel Gyan ◽  
Olivier Tournilhac ◽  
Christelle Halty ◽  
Richard Veyrat-Masson ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Docosahexaenoic Acid ◽  
Lymphocytic Leukemia ◽  
Dependent Manner ◽  
Omega 3 ◽  
Infectious Risk ◽  
Highly Active ◽  
Primary Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia is an indolent disorder with an increased infectious risk remaining one of the main causes of death. Development of therapies with higher safety profile is thus a challenging issue. Docosahexaenoic acid (DHA, 22:6) is an omega-3 fatty acid, a natural compound of normal cells, and has been shown to display antitumor potency in cancer. We evaluated the potential <em>in</em> <em>vitro</em> effect of DHA in primary CLL cells. DHA induces high level of <em>in</em> <em>vitro</em> apoptosis compared to oleic acid in a dose-dependent and time-dependent manner. Estimation of IC50 was only of 4.813 μM, which appears lower than those reported in solid cancers. DHA is highly active on CLL cells <em>in vitro.</em> This observation provides a rationale for further studies aiming to understand its mechanisms of action and its potent <em>in vivo</em> activity.

The Novel Histone Deacetylase Inhibitor OSU-HDAC42 Has Class I and II Histone Deacetylase (HDAC) Inhibitory Activity and Represents a Novel Therapy for Chronic Lymphocytic Leukemia.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2807-2807
Author(s):  
Derek A. West ◽  
David M. Lucas ◽  
Melanie E. Davis ◽  
Michael D. De Lay ◽  
Amy J. Johnson ◽  
...  
Keyword(s):  
Cell Death ◽  
Chronic Lymphocytic Leukemia ◽  
Histone Deacetylase ◽  
Inhibitory Activity ◽  
Hdac Inhibitors ◽  
Clinical Development ◽  
Lymphocytic Leukemia ◽  
In Vivo Efficacy

Abstract Inhibitors of histone deacetylase (HDAC) have generated major interest for the treatment of multiple cancers including B-cell Chronic Lymphocytic Leukemia (CLL). To date, HDAC inhibitors introduced for clinical development in CLL have been associated either with suboptimal activity relative to concentrations required to mediate cytotoxicity in vitro (Valproic Acid, MS-275, SAHA), or demonstrate unacceptable acute or long-term toxicities (depsipeptide) that limit their clinical potential. Fortunately, several alternative HDAC inhibitors are in pre-clinical or early clinical development. One such agent currently undergoing pre-clinical testing by the National Cancer Institute-sponsored RAID program is OSU-HDAC42 (s-HDAC-42), a novel, orally bioavailable phenylbutyrate-derived HDAC inhibitor with both in vitro and in vivo efficacy against prostate cancer cells. We therefore tested OSU-HDAC42 against CD19-positive cells obtained from patients with CLL to determine its potential in this disease. The LC50 of OSU-HDAC42 in CLL cells was 0.46 uM at 48 hours of continuous incubation by MTT assay, which was corroborated by annexin V-FITC/propidium iodide flow cytometry. To determine the minimum amount of time that OSU-HDAC42 must be present to induce cell death, cells were incubated for various times, washed, resuspended in fresh media without drug, then assessed by MTT at a total of 48 hours incubation. The effects of OSU-HDAC42 were eliminated in CLL cells when drug was removed after 4 or 6 hours. However, there was a gradual increase in effect over time, and by 16 hours, approximately 60% of the cytotoxicity achieved with continuous incubation was retained. OSU-HDAC42 induced acetylation of histone proteins H3 and H4 as early as 4 hours that was dose and time dependent. LC/MS interrogation of OSU-HDAC42-treated CLL cells is currently underway to determine specific post-translational modification changes of all histone proteins and variants. OSU-HDAC42 also was able to sensitize CLL cells to TNF-Related Apoptosis Inducing Ligand (TRAIL) at 24 hours in a dose-dependent manner, supporting its class I HDAC inhibitory activity as recently reported by Inoue and colleagues (Cancer Res.2006; 66:6785). Evidence of class II HDAC inhibitory activity was also observed with OSU-HDAC42 at 12 hours with acetylation of tubulin. Unlike depsipeptide, OSU-HDAC42 activated both caspase-8 and -9 followed by PARP processing. Cell death induced by OSU-HDAC42 was completely inhibited with pre-treatment by the pan-caspase inhibitor Z-VAD-FMK. In vivo experiments are underway to examine the efficacy of OSU-HDAC42 in several murine models of leukemia to confirm in vivo efficacy as well as influence on murine effector cells. Our data strongly support continued investigation of OSU-HDAC42 in CLL and related B-cell malignancies.

scholarly journals EXTH-62. PRECLINICAL EFFICACY OF THE IMIPRIDONE ONC-206 AGAINST MEDULLOBLASTOMA

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii100-ii101
Author(s):  
Tobey MacDonald ◽  
Anshu Malhotra ◽  
Jingbo Liu ◽  
Hongying Zhang ◽  
Matthew Schneiderjan ◽  
...  
Keyword(s):  
Cell Death ◽  
Malignant Glioma ◽  
Ex Vivo ◽  
Clinical Results ◽  
Normal Brain ◽  
Dependent Manner ◽  
Group 3 ◽  
Dose Dependent

Abstract Treatment for medulloblastoma (MB) is typically ineffective for MYC amplified or metastatic SHH, Group 3 and 4 subgroups. Promising preclinical and clinical results have been obtained for adult and pediatric malignant glioma treated with ONC-201, a selective antagonist of DRD2, a G-protein coupled receptor that regulates prosurvival pathways. Herein, we report the activity of ONC-201 and ONC-206, which has increased non-competitive antagonism of DRD2, against MB. We treated three different MB cell types representative of SHH- and Group 3-like cells, with varied levels of DRD2 expression, and consistently observed increased cell death in a dose-dependent manner at lower doses of ONC-206 compared to ONC-201. We also evaluated ClpP as an additional drug target in MB. ClpP is a mitochondrial protease that has been shown to directly bind and be activated by ONC 201, and is highly expressed at the protein level across pediatric MB, malignant glioma and ATRT, but not normal brain. We observed that similar to ONC-201, ONC-206 treatment of MB cells induces the restoration of mitochondrial membrane potential to the non-proliferative state, degradation of the mitochondrial substrate SDHB, reduction in survivin and elevation in ATF4 (integrated stress response). Importantly, ONC-206 treatment induced significant cell death of patient-derived SHH, WNT, and Group 3 tumors ex vivo and Group 4 cells in vitro, while having no observable toxicity in normal brain. ONC-206 treatment of a transgenic mouse model of Shh MB in vivo significantly reduces tumor growth and doubles survival time in a dose-dependent manner following 2 weeks of therapy. Additional in vivo data will be reported in preparation for a planned Phase I study of ONC-206 in children with malignant brain tumors.

The Valproic Acid-Fludarabine Combination Induces a Synergistic Response in Chronic Lymphocytic Leukemia Via a Mechanism Involving the Lysosomal Protease Cathepsin B.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2892-2892
Author(s):  
Ju-Yoon Yoon ◽  
David Szwajcer ◽  
Ganchimeg Ishdorj ◽  
Pat Benjaminson ◽  
James B Johnston ◽  
...  
Keyword(s):  
Valproic Acid ◽  
Cell Death ◽  
Chronic Lymphocytic Leukemia ◽  
Cathepsin B ◽  
Leukemic Cell ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells ◽  
Lysosomal Protease

Abstract Abstract 2892 Chronic Lymphocytic Leukemia (CLL) is the most common haematological malignancy in the western world. Fludarabine, a nucleoside analogue, is commonly used to treat Chronic Lymphocytic Leukemia (CLL) in untreated and relapsed CLL. However, patients commonly develop resistance to fludarabine. We hypothesize that the addition of Valproic Acid (VPA), an inhibitor of histone deacetylases (HDACs), can improve fludarabine-based therapy. The VPA-Fludarabine combination induced a synergistic response in human leukemic cells and primary CLL cells. Fludarabine also interacted synergistically with three other HDAC inhibitors, suberoylanilide hydroxamic acid (SAHA), Trichostatin A, and sodium butyrate, while the synergy was not observed with valpromide, the VPA analogue that does not inhibit HDACs. We confirmed that fludarabine treatment activates caspases-8, -9 and caspase-3, and we also show that fludarabine treatment activates caspase-2, an upstream caspase that has been implicated in cell death associated with lysosome membrane permeabilization (LMP). Activation of all four caspases was enhanced by the addition of VPA. Enhanced activation of caspases was associated with down-regulation of two prominent anti-apoptotic proteins, Mcl-1 and XIAP. The down-regulation of Mcl-1 and XIAP was dependent on the lysosomes, as their alkalinization using either chloroquine or NH4Cl partially stabilized both proteins, leading to reduced apoptosis. Chemical inhibition of a specific lysosomal protease, cathepsin B, using CA074-Me, was sufficient to stabilize Mcl-1 and XIAP, reduce caspase activation and apoptosis. Treatment with fludarabine or the VPA-fludarabine combination led to the loss of lysosome integrity, as visualized by fluorescent staining, thus suggesting a leakage of the lysosomal content into the cytosol in response to the drugs. Addition of purified cathepsin B to leukemic cell lysates led to the reduction in protein levels of Mcl-1, XIAP and pro-caspase-2, thus suggesting that the re-localization of cathepsin B into the cytosol is sufficient to drive cell death. VPA treatment enhanced cathepsin B levels in both leukemic cell lines and primary CLL cells. When cathepsin B activity was examined using zRR-AMC, a fluorogenic substrate of cathepsin B, VPA also increased cathepsin B activity, and this activity was abolished by the addition of CA074-Me. In parallel with the in vitro/ex vivo experiments, we had launched a phase II clinical trial at CancerCare Manitoba. Six relapsed CLL patients who had received at least one prior therapy with fludarabine were examined. No responses were seen after 28 days using VPA alone, in line with the in vitro observation of minimal cytotoxicity of VPA at low doses. However, in five patients who continued on VPA with fludarabine, three patients showed a >50% fall in lymphocyte/lymph node size after receiving five cycles of the combination. When the leukemic cells from VPA-treated CLL patients were examined, VPA administration induced increased levels of histone-3 acetylation and cathepsin B in vivo. In summary, a novel mechanism for fludarabine cytotoxicity has been elucidated, where fludarabine induces a loss of lysosomal integrity, leading to cathepsin B-dependent cell death. VPA interacted with fludarabine synergistically, and this synergy was associated with the VPA-induced increase in VPA level and activity. VPA induced increase in histone-3 acetylation and cathepsin B in vivo, and this induction of cathepsin B is likely to be contributing to the clinical response observed in fludarabine-relapsed/refractory CLL patients. Disclosures: Off Label Use: Valproic acid as adjunct therapy in Chronic Lymphocytic Leukemia. Johnston:Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

A6 Peptide Is Selectively Cytotoxic For Chronic Lymphocytic Leukemia Cells

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 5303-5303
Author(s):  
Suping Zhang ◽  
Hsien Lai ◽  
Grace Liu ◽  
Laura Rassenti ◽  
Michael Y. Choi ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Lymphocytic Leukemia ◽  
Surface Glycoprotein ◽  
Leukemia Cells ◽  
Dependent Manner ◽  
Cell Surface Glycoprotein

Abstract Chronic lymphocytic leukemia (CLL) cells express high levels of CD44, a cell-surface glycoprotein receptor for hyaluronic acid (HA). We found that a mAb specific for CD44 was directly cytotoxic for leukemia B cells, but had little effect on normal B cells. Moreover, this anti-CD44 mAb could induce CLL cells that expressed the zeta-associated protein of 70 kDa (ZAP-70) to undergo caspase-dependent apoptosis, independent of complement or cytotoxic effector cells (Proc Natl Acad Sci, USA 2013, PMID: 23530247). The cytotoxic effect of this mAb was not mitigated when the CLL cells were co-cultured with mesenchymal stromal cells (MSCs) or hyaluronic acid or when they were stimulated via ligation of the B-cell receptor with anti-µ. A6 (Angstrom Pharmaceuticals) is an 8-amino acid peptide that has marked homology with a linear sequence of CD44. A6 can bind CD44 within a region of the ligand-binding domain, leading to inhibition of the migration and metastatic potential of CD44-expressing cancer cells in vitro and in vivo (Mol Cancer Ther, 2011 PMID: 21885863). We evaluated the cytotoxic activity of A6 against primary leukemia cells of patients with CLL (n = 22). We found that A6 peptide also was directly cytotoxic for CLL cells isolated from different patients in a dose-dependent manner at concentrations that may be achieved in vivo. The A6 peptide appeared less cytotoxic for CLL cells than the intact anti-CD44 mAb, but still had greater direct cytotoxicity for CLL cells that expressed ZAP-70 than for CLL cells that were ZAP-70 negative. Furthermore, the A6 peptide had negligible effect on the viability of lymphocytes isolated from the blood of healthy donors (n = 3). Because clinical studies have found the A6 peptide to be well-tolerated and without dose-limiting toxicity in patients with solid tumors who have been treated to date (N = 40), a clinical study is planned to evaluate the safety and activity of the A6 peptide in the treatment of patients with CLL. Disclosures: Howell: Angstrom Phamaceuticals: Membership on an entity’s Board of Directors or advisory committees. Finlayson:Angstrom Phamaceuticals: Employment.

scholarly journals Expression of Apoptosis-Regulating Proteins in Chronic Lymphocytic Leukemia: Correlations With In Vitro and In Vivo Chemoresponses

Blood ◽  
1998 ◽  
Vol 91 (9) ◽  
pp. 3379-3389 ◽  
Author(s):  
Shinichi Kitada ◽  
Janet Andersen ◽  
Sophie Akar ◽  
Juan M. Zapata ◽  
Shinichi Takayama ◽  
...  
Keyword(s):  
Cell Death ◽  
Chronic Lymphocytic Leukemia ◽  
Caspase 3 ◽  
Single Agent ◽  
White Blood Cells ◽  
Lymphocytic Leukemia ◽  
In Vitro Chemosensitivity ◽  
Apoptotic Protein

Abstract B-cell chronic lymphocytic leukemia (B-CLL) represents a neoplastic disorder caused primarily by defective programmed cell death (PCD), as opposed to increased cell proliferation. Defects in the PCD pathway also contribute to chemoresistance. The expression of several apoptosis-regulating proteins, including the Bcl-2 family proteins Bcl-2, Bcl-XL, Mcl-1, Bax, Bak, and BAD; the Bcl-2–binding protein BAG-1; and the cell death protease Caspase-3 (CPP32), was evaluated by immunoblotting using 58 peripheral blood B-CLL specimens from previously untreated patients. Expression of Bcl-2, Mcl-1, BAG-1, Bax, Bak, and Caspase-3 was commonly found in circulating B-CLL cells, whereas the Bcl-XL and BAD proteins were not present. Higher levels of the anti-apoptotic protein Mcl-1 were strongly correlated with failure to achieve complete remission (CR) after single-agent therapy (fludarabine or chlorambucil) (P = .001), but the presence of only seven CRs among the 42 patients for whom follow-up data were available necessitates cautious interpretation of these observations. Higher levels of the anti-apoptotic protein BAG-1 were also marginally associated with failure to achieve CR (P = .04). Apoptosis-regulating proteins were not associated with patient age, sex, Rai stage, platelet count, hemoglobin (Hb) concentration, or lymph node involvement, although higher levels of Bcl-2 and a high Bcl-2:Bax ratio were correlated with high numbers (>105/μL) of white blood cells (WBC) (P = .01; .007) and higher levels of Bak were weakly associated with loss of allelic heterozygosity at 13q14 (P = .04). On the basis of measurements of apoptosis induction by fludarabine using cultured B-CLL specimens, in vitro chemosensitivity data failed to correlate with in vivo clinical response rates (n = 42) and expression of the various apoptosis-regulating proteins. Although larger prospective studies are required before firm conclusions can be reached, these studies show the expression in B-CLLs of multiple apoptosis-regulating proteins and suggest that the relative levels of some of these, such as Mcl-1, may provide information about in vivo responses to chemotherapy. In vitro chemosensitivity data, however, do not appear to be particularly useful in predicting responses in B-CLL.

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