Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Interactions between the small molecule Bcl-2 inhibitor HA14-1 and proteasome inhibitors, including bortezomib (Velcade; formerly known as PS-341) and MG-132, have been examined in human multiple myeloma cells. Sequential (but not simultaneous) exposure of MM.1S cells to bortezomib or MG-132 (10 h) followed by HA14-1 (8 h) resulted in a marked increase in mitochondrial injury (loss of DeltaPsim, cytochrome c, Smac/DIABLO, and apoptosis-inducing factor release), activation of procaspases-3, -8, and -9, and Bid, induction of apoptosis, and loss of clonogenicity. Similar interactions were observed in U266 and MM.1R dexamethasone-resistant myeloma cells. These events were associated with Bcl-2 cleavage, Bax, Bak, and Bad accumulation, mitochondrial translocation of Bax, abrogation of Mcl-1, Bcl-xL, and XIAP upregulation, and a marked induction of JNK and p53. Bortezomib/HA14-1 treatment triggered an increase in reactive oxygen species (ROS), which, along with apoptosis, was blocked by the free radical scavenger N-acetyl-L-cysteine (L-NAC). L-NAC also opposed bortezomib/HA14-1-mediated JNK activation, upregulation of p53 and Bax, and release of cytochrome c and Smac/DIABLO. Finally, bortezomib/HA14-1-mediated apoptosis was unaffected by exogenous IL-6. Together, these findings indicate that sequential exposure of myeloma cells to proteasome and small molecule Bcl-2 inhibitors such as HA14-1 may represent a novel therapeutic strategy in myeloma.
Leukemia 2003 Oct
PMID:The proteasome inhibitor bortezomib promotes mitochondrial injury and apoptosis induced by the small molecule Bcl-2 inhibitor HA14-1 in multiple myeloma cells. 1451 55

Interactions between proteasome and cyclin-dependent kinase inhibitors have been examined in human leukemia cells in relation to induction of apoptosis. Simultaneous exposure (24 h) of U937 myelomonocytic leukemia cells to 100 nM flavopiridol and 300 nM MG-132 resulted in a marked increase in mitochondrial injury (cytochrome c, Smac/DIABLO release, loss of deltaPsi(m)), caspase activation, and synergistic induction of cell death, accompanied by a marked decrease in clonogenic potential. Similar effects were observed with other proteasome inhibitors (e.g., Bortezomib (VELCADE trade mark bortezomib or injection), lactacystin, LLnL) and cyclin-dependent kinase inhibitors (e.g., roscovitine), as well as other leukemia cell types (e.g., HL-60, Jurkat, Raji). In U937 cells, synergistic interactions between MG-132 and flavopiridol were associated with multiple perturbations in expression/activation of signaling- and survival-related proteins, including downregulation of XIAP and Mcl-1, activation of JNK and p34(cdc2), and diminished expression of p21(CIP1). The lethal effects of MG-132/flavopiridol were not reduced in leukemic cells ectopically expressing Bcl-2, but were partially attenuated in cells ectopically expressing dominant-negative caspase-8 or CrmA. Flavopiridol/proteasome inhibitor-mediated lethality was also significantly diminished by agents and siRNA blocking JNK activation. Lastly, coadministration of MG-132 with flavopiridol resulted in diminished DNA binding of NF-kappaB. Notably, pharmacologic interruption of the NF-kappaB pathway (e.g., by BAY 11-7082, PDTC, or SN-50) or molecular dysregulation of NF-kappaB (i.e., in cells ectopically expressing an IkappaBalpha super-repressor) mimicked the actions of proteasome inhibitors in promoting flavopiridol-induced mitochondrial injury, JNK activation, and apoptosis. Together, these findings indicate that proteasome inhibitors strikingly lower the apoptotic threshold of leukemic cells exposed to pharmacologic CDK inhibitors, and suggest that interruption of the NF-kappaB cytoprotective pathway and JNK activation both play key roles in this phenomenon. They also raise the possibility that combining proteasome and CDK inhibitors could represent a novel antileukemic strategy.
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PMID:Proteasome inhibitors potentiate leukemic cell apoptosis induced by the cyclin-dependent kinase inhibitor flavopiridol through a SAPK/JNK- and NF-kappaB-dependent process. 1456 39

The hierarchy of events accompanying induction of apoptosis by the proteasome inhibitor Bortezomib was investigated in Jurkat lymphoblastic and U937 myelomonocytic leukemia cells. Treatment of Jurkat or U937 cells with Bortezomib resulted in activation of c-Jun-N-terminal kinase (JNK) and p38 MAPK (mitogen-activated protein kinase), inactivation of extracellular signal-regulating kinase 1/2 (ERK1/2), cytochrome c release, caspase-9, -3, and -8 activation, and apoptosis. Bortezomib-mediated cytochrome c release and caspase activation were blocked by the pharmacologic JNK inhibitor SP600125, but lethality was not diminished by the p38 MAPK inhibitor SB203580. Inducible expression of a constitutively active MEK1 construct blocked Bortezomib-mediated ERK1/2 inactivation, significantly attenuated Bortezomib lethality, and unexpectedly prevented JNK activation. Conversely, pharmacologic MEK/ERK1/2 inhibition promoted Bortezomib-mediated JNK activation and apoptosis. Lastly, the antioxidant N-acetyl-l-cysteine (LNAC) attenuated Bortezomib-mediated reactive oxygen species (ROS) generation, ERK inactivation, JNK activation, mitochondrial dysfunction, and apoptosis. In contrast, enforced MEK1 and ERK1/2 activation or JNK inhibition did not modify Bortezomib-induced ROS production. Together, these findings suggest that in human leukemia cells, Bortezomib-induced oxidative injury operates at a proximal point in the cell death cascade to antagonize cytoprotective ERK1/2 signaling, promote activation of the stress-related JNK pathway, and to trigger mitochondrial dysfunction, caspase activation, and apoptosis. They also suggest the presence of a feedback loop wherein Bortezomib-mediated ERK1/2 inactivation contributes to JNK activation, thereby amplifying the cell death process.
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PMID:The hierarchical relationship between MAPK signaling and ROS generation in human leukemia cells undergoing apoptosis in response to the proteasome inhibitor Bortezomib. 1509 52

Graft-versus-host disease (GVHD) represents a major hurdle impeding the efficacy of allogeneic bone marrow transplantation (BMT). Bortezomib is a proteasome inhibitor that was recently approved for treatment of myeloma. We found that bortezomib potently inhibited in vitro mixed lymphocyte responses and promoted the apoptosis of alloreactive T cells. Bortezomib given at the time of allogeneic BMT in mice resulted in significant protection from acute GVHD. Reductions in GVHD-associated parameters and biological evidence of proteasome inhibition were observed with this regimen but with no adverse effects on long-term donor reconstitution. Assessment of graft-versus-tumor responses in advanced leukemia-bearing mice demonstrated that only the combination of allogeneic BMT and T cells with bortezomib promoted significant increases in survival. Increased cytotoxic T cell killing of the tumor was also observed. Thus, the combination of proteasome inhibition with selective immune attack can markedly increase the efficacy of BMT in cancer.
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PMID:Inhibition of acute graft-versus-host disease with retention of graft-versus-tumor effects by the proteasome inhibitor bortezomib. 1514 7

Adult T-cell leukemia (ATL) is a fatal neoplasm derived from CD4-positive T-lymphocytes, and regardless of intensive chemotherapy, its mean survival time is less than 1 year. Nuclear factor-kappaB (NF-kappaB) activation was reported in HTLV-I associated cells, and has been implicated in oncogenesis and resistance to anticancer agents and apoptosis. We studied the effect of a proteasome inhibitor, bortezomib (formerly known as PS-341), on ATL cells in vitro and in vivo. Bortezomib could inhibit the degradation of IkappaBalpha in ATL cells, resulting in suppression of NF-kappaB and induction of cell death in ATL cells in vitro. Susceptibilities to bortezomib were well correlated with NF-kappaB activation, suggesting that suppression of the NF-kappaB pathway was implicated in the cell death induced by bortezomib. Although the majority of the cell death was apoptosis, necrotic cell death was observed in the presence of a caspase inhibitor, z-VAD-fmk. When bortezomib was administered into SCID mice bearing tumors, it suppressed tumor growth in vivo, showing that bortezomib was effective against ATL cells in vivo. These studies revealed that bortezomib is highly effective against ATL cells in vitro and in vivo by induction of apoptosis, and its clinical application might improve the prognosis of patients with this fatal disease.
Leukemia 2004 Aug
PMID:Proteasome inhibitor, bortezomib, potently inhibits the growth of adult T-cell leukemia cells both in vivo and in vitro. 1519 Feb 57

Hematologic malignancies, including multiple myeloma (MM), will account for more than 100,000 new cases of cancer and over 57,000 deaths in the United States in 2003. Treatment of MM is a serious challenge, because despite a variety of available therapies, median survival is short. A new therapeutic area focuses on inhibiting the activity of the proteasome, a 26S protease complex involved in cell cycle regulation, cell adhesion, inflammation, and protein turnover. The novel proteasome inhibitor, bortezomib (Velcade), was recently approved for use in patients with refractory and relapsed MM and to date is the only proteasome inhibitor to have entered clinical trials. Bortezomib has demonstrated activity with manageable toxicity in a variety of hematologic malignancies in addition to MM, including leukemia and non-Hodgkin's lymphoma. This article reviews clinical information on bortezomib in hematologic malignancies both as monotherapy and in combination with dexamethasone. Preliminary reports of bortezomib in combination with Doxil (pegylated liposomal doxorubicin), melphalan, and thalidomide are discussed, and current trials are described. Available data suggest that bortezomib will be useful in the treatment of a variety of hematologic malignancies.
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PMID:Proteasome inhibition in hematologic malignancies. 1522 57

Primary effusion lymphomas (PELs) are a rare type of non-Hodgkin's lymphoma that are resistant to cytotoxic chemotherapy. PELs manifest constitutive activation of nuclear factor kappa B (NF-kappaB), and inhibition of NF-kappaB induces apoptosis of PELs and sensitizes to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced death. Bortezomib (PS-341), a peptidyl boronic acid inhibitor of the proteasome, is a potent agent against a wide range of hematologic malignancies and has been shown to inhibit NF-kappaB. Thus, we examined the cytotoxic effects of bortezomib alone and in combination with various drugs. Bortezomib potently inhibited NF-kappaB in PEL cells in a dose-dependent manner. In addition, bortezomib inhibited growth and induced apoptosis of PEL cell lines (IC(50) values of 3.4-5.0 nM). Results of drug interactions between bortezomib and chemotherapy (doxorubicin and Taxol) were schedule-dependent: synergistic interactions were generally observed when PEL cells were pretreated with bortezomib prior to chemotherapy, whereas additive or even antagonistic interactions occurred with chemotherapy pretreatment or simultaneous treatment with bortezomib and chemotherapy. Most schedules of bortezomib and dexamethasone were synergistic, although pretreatment with dexamethasone resulted in additive interactions. Effects of combinations of bortezomib and TRAIL were generally additive. Thus, bortezomib represents a promising potential therapy for the treatment of PEL.
Leukemia 2004 Oct
PMID:Antitumor effects of bortezomib (PS-341) on primary effusion lymphomas. 1534 45

Bortezomib (VELCADE) is a proteasome inhibitor, which has been recently used for the treatment of relapsed/refractory multiple myeloma (MM) with encouraging results. Tumour lysis syndrome (TLS) has been described during chemotherapy for many haematological malignancies, such as acute lymphoblastic leukaemia and high-grade lymphomas. TLS is very rare in MM with ten reported cases, including approximately 1% of patients receiving high-dose chemotherapy with stem cell support (ASCT). We report here a patient with refractory MM and deletion 13q, who had received more than four lines of previous treatment, including two ASCT, and had relapsed. The patient received bortezomib, as a single agent, at a dose of 1.3 mg/m(2) twice per week for 2 weeks, in a 3-week cycle, and developed TLS after the second dose of cycle one. Bortezomib therapy, due to the rapidity of its action, may result in TLS in myeloma patients who have rapidly proliferative disease with a high tumour burden. Therefore, TLS should be looked for during the first cycle of bortezomib treatment and suitable precautions should be considered.
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PMID:Tumour lysis syndrome in multiple myeloma after bortezomib (VELCADE) administration. 1544 88

Bortezomib is a highly selective, reversible inhibitor of the 26S proteasome that is indicated for single-agent use in the treatment of patients with multiple myeloma who have received at least 2 prior therapies and are progressing on their most recent therapy. Clinical investigations have been completed or are under way to evaluate the safety and efficacy of bortezomib alone or in combination with chemotherapy in multiple myeloma, both at relapse and presentation, as well as in other cancer types. The antiproliferative, proapoptotic, antiangiogenic, and antitumor activities of bortezomib result from proteasome inhibition and depend on the altered degradation of a host of regulatory proteins. Exposure to bortezomib has been shown to stabilize p21, p27, and p53, as well as the proapoptotic Bid and Bax proteins, caveolin-1, and inhibitor kappaB-alpha, which prevents activation of nuclear factor kappaB-induced cell survival pathways. Bortezomib also promoted the activation of the proapoptotic c-Jun-NH2 terminal kinase, as well as the endoplasmic reticulum stress response. The anticancer effects of bortezomib as a single agent have been demonstrated in xenograft models of multiple myeloma, adult T-cell leukemia, lung, breast, prostate, pancreatic, head and neck, and colon cancer, and in melanoma. In these preclinical in vivo studies, bortezomib treatment resulted in decreased tumor growth, angiogenesis, and metastasis, as well as increased survival and tumor apoptosis. In several in vitro and/or in vivo cancer models, bortezomib has also been shown to enhance the antitumor properties of several antineoplastic treatments. Importantly, bortezomib was generally well tolerated and did not appear to produce additive toxicities when combined with other therapies in the dosing regimens used in these preclinical in vivo investigations. These findings provide a rationale for further clinical trials using bortezomib alone or in combination regimens with chemotherapy, radiation therapy, immunotherapy, or novel agents in patients with hematologic malignancies or solid tumors.
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PMID:Preclinical evaluation of the proteasome inhibitor bortezomib in cancer therapy. 1592 91

The proteasome inhibitor PSI is potently cytotoxic in vitro against human chronic myeloid leukemia (CML) and acute myeloid leukemias (AML). Here, we have tested proteasome inhibitor I (PSI) in a panel of 11 human multiple myeloma (MM) cell lines and found that it has antiproliferative activity, with an IC50 between 4.5 and 557 nM at 48 h. PSI potentiated the toxicity of a number of chemotherapeutic agents in myeloid leukemia but not in MM cell lines, while in combination with therapeutic proteasome inhibitor PS-341 (Bortezomib) it had a synergistic effect. PSI suppressed the growth of AML cell lines more effectively than PS-341. CFU-GM colony assays revealed that CD34+ bone marrow progenitors from CML and AML patients were more sensitive to PSI than those from normal subjects (IC50: 5, 15 and 50 nM for AML, CML and normal, respectively). Moreover, the growth of normal primitive progenitors (LTC-IC) was unaffected by 15 nM PSI (P=0.576). PSI-induced cell death required RNA transcription and protein synthesis, but not DNA replication, was accompanied by the upregulation of Bcl-2 and modest reduction of Bax and Bcl-XL proteins, and involved the activation of caspases 2, 3, 7 and 8. These findings lend additional support to preclinical investigations with PSI.
Leukemia 2005 Dec
PMID:Sensitivity of human multiple myelomas and myeloid leukemias to the proteasome inhibitor I. 1622 84


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