Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0026764 (multiple myeloma)
 36,148 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The proteasome is a multicatalytic proteinase complex responsible for the degradation of most intracellular proteins, including proteins crucial to cell cycle regulation and programmed cell death, or apoptosis. In preclinical cancer models, proteasome inhibitors induce apoptosis, have in vivo antitumor efficacy, and sensitize malignant cells and tumors to the proapoptotic effects of conventional chemotherapeutics and radiation therapy. Interestingly, transformed cells display greater susceptibility to proteasome inhibition than nonmalignant cells. Therefore, proteasome inhibition holds promise as a novel approach to the treatment of cancer. Inhibitors of the proteasome impact on cells in part through down-regulation of nuclear factor kappaB, but also through modulation of cell cycle proteins and other pro- and antiapoptotic pathways. Bortezomib (VELCADE; formerly PS-341), the first such inhibitor to undergo clinical testing, has demonstrated impressive antitumor activity and manageable toxicities in Phase I and II trials both as a single agent, and in combination with other drugs. It has been approved recently by the Food and Drug Administration for therapy of patients with multiple myeloma who have received at least two prior regimens and progressed on the last of these. Ongoing preclinical evaluations of the mechanisms that underlie the antitumor effects of proteasome inhibitors, and clinical trials in a variety of tumor types, will allow additional refinement of the role these agents will play in cancer therapy. Below we discuss the rationale behind targeting the proteasome for cancer therapy, and review the preclinical and clinical data on proteasome inhibitors alone, and in combination with conventional chemotherapeutics.
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PMID:The proteasome as a target for cancer therapy. 1469 30

Histone deacetylases (HDACs) affect cell growth at the transcriptional level by regulating the acetylation status of nucleosomal histones. HDAC inhibition induces differentiation and/or apoptosis in transformed cells. We recently showed that HDAC inhibitors, such as suberoylanilide hydroxamic acid (SAHA), potently induce apoptosis of human multiple myeloma (MM) cells. In this study, we focused on MM as a model to study the transcriptional profile of HDAC inhibitor treatment on tumor cells and to address their pathophysiological implications with confirmatory mechanistic and functional assays. We found that MM cells are irreversibly committed to cell death within few hours of incubation with SAHA. The hallmark molecular profile of MM cells before their commitment to SAHA-induced cell death is a constellation of antiproliferative and/or proapoptotic molecular events, including down-regulation of transcripts for members of the insulin-like growth factor (IGF)/IGF-1 receptor (IGF-1R) and IL-6 receptor (IL-6R) signaling cascades, antiapoptotic molecules (e.g., caspase inhibitors), oncogenic kinases, DNA synthesis/repair enzymes, and transcription factors (e.g., XBP-1, E2F-1) implicated in MM pathophysiology. Importantly, SAHA treatment suppresses the activity of the proteasome and expression of its subunits, and enhances MM cell sensitivity to proteasome inhibition by bortezomib (PS-341). SAHA also enhances the anti-MM activity of other proapoptotic agents, including dexamethasone, cytotoxic chemotherapy, and thalidomide analogs. These findings highlight the pleiotropic antitumor effects of HDAC inhibition, and provide the framework for future clinical applications of SAHA to improve patient outcome in MM.
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PMID:Transcriptional signature of histone deacetylase inhibition in multiple myeloma: biological and clinical implications. 1469 87

Multiple myeloma is the second most common hematologic malignancy with currently no definitive treatment available. Although, therapy may include allogenic bone marrow transplantation, high-dose ablative chemotherapy followed by bone marrow or peripheral stem cell transplantation, melphalan/corticosteroid therapy, alpha-interferon treatment, and combined cytostatic chemotherapy, currently none of these alternatives offer cure for the disease. Introduction of thalidomide into the therapeutic arsenal provided a breakthrough in the treatment of refractory and/or relapsing disease, however, clinical experience indicated need for alternative treatments for thalidomide resistant disease as well as for intolerant patients. Proteasome inhibitors, hallmarked by bortezomib may represent one of the much needed therapeutic options. The results of the SUMMIT investigation that involved 202 heavily pretreated patients were convincing enough to prompt the FDA to register this drug for the treatment of multiple myeloma. Its European registration is also underway. In this review, the proteasome and its inhibition as a pharmacotherapeutic avenue are introduced. The most important clinical studies employing bortezomib and its combinations are also detailed. It is the hope of the authors that bortezomib and its derivatives will soon belong to the clinical armory against multiple myeloma.
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PMID:[Proteasome inhibition: a new therapeutic approach for the treatment of multiple myeloma]. 1497 77

PS-341 (bortezomib) represents a new class of therapeutics that targets the ubiquitin-proteasome pathway. It has broad-spectrum single-agent anticancer activity and can potentiate chemotherapy and radiation in preclinical models. Early phase clinical studies have shown tolerability and activity in multiple myeloma, lymphoma, prostate cancer, and lung cancers. By its mechanism of inhibiting protein degradation, PS-341 targets a wide range of pathways relevant to tumor progression and therapy resistance and can directly modulate expression of cyclins, p27(Kip1), p53, nuclear factor-kappaB, Bcl-2, and Bax. PS-341 is currently in phase I/II clinical development in both non-small cell lung cancer and small cell lung cancer. This article will review the preclinical and clinical experience with PS-341 as it relates to lung cancer.
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PMID:Proteasome inhibition with PS-341 (bortezomib) in lung cancer therapy. 1498 79

Proteasome inhibitor PS-341 induces growth arrest and apoptosis of multiple myeloma (MM) cells via inactivation of nuclear factor kappaB (NF-kappaB) in vitro. In addition, recent clinical studies of PS-341 have demonstrated some objective responses in individuals with relapsed, refractory MM. However, the activity of PS-341 against non-hematological malignancies remains to be fully elucidated. In this study, we found that PS-341 induced growth arrest and apoptosis of androgen-dependent human prostate cancer LNCaP cells in conjunction with markedly up-regulated levels of p21(waf1) and p53. In addition, we found that PS-341 down-regulated both 5alpha-dihydrotestosterone (DHT)- and interleukin-6 (IL-6)-induced expression of prostate-specific antigen (PSA) as measured by western blot analysis. PS-341 down-regulated basal levels of the androgen receptor (AR) in the nucleus; however, it did not affect DHT-induced nuclear translocation of AR in these cells. Reporter assays using a series of promoters of the PSA gene showed that down-regulation of PSA by PS-341 was caused by inhibition of the transcriptional activity of the androgen receptor response element (ARE) in these cells. Taken together, the results indicate that PS-341 induced growth arrest and apoptosis of LNCaP cells by blockade of the AR signaling pathway. The proteasome may be a molecular target for treatment of a variety of cancers including prostate cancer.
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PMID:Proteasome inhibitor PS-341 down-regulates prostate-specific antigen (PSA) and induces growth arrest and apoptosis of androgen-dependent human prostate cancer LNCaP cells. 1501 28

Monoclonal gammopathies are characterized by the overproduction of a monoclonal immunoglobulin (M-Protein), which may be detected in serum or urine by protein electrophoresis and immunofixation. The presence of an M-Protein results from the proliferation of a single abnormal clone of differentiated B lymphocytes or plasma cells, and is associated with a variety of clinical conditions, ranging from asymptomatic to malignant disease. Recent years have witnessed considerable advances in the treatment of plasma cell myeloma, the most common malignant disorder of the monoclonal gammopathies. As compared with conventional-dose treatments, high-dose chemotherapy with autologous stem-cell transplantation increases response rates and overall survival of patients with myeloma who are younger than 65 years of age. Progress in supportive therapies and the development of promising new drugs such as proteasome inhibitors and thalidomide analogues may provide further benefits for myeloma patients in the future.
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PMID:[Monoclonal gammopathies--from MGUS to myeloma]. 1501

The multicatalytic proteinase complex, or proteasome, is responsible for the majority of regulated eukaryotic protein turnover through the ubiquitin-proteasome pathway. Bortezomib (Velcade, Millennium Pharmaceuticals, Inc.), the first drug specifically designed to target the proteasome, has recently entered the clinical arena. Previous preclinical studies showed that bortezomib had a unique cytotoxicity profile and that proteasome inhibition in vivo could be achieved safely with concomitant antitumor efficacy. In clinical studies, bortezomib has shown remarkable single-agent activity against relapsed and refractory multiple myeloma in both Phase I and II trials. Based on the latter, bortezomib has been approved by the US Food and Drug Administration for patients who have received two prior regimens and progressed on the second of these. Early results with bortezomib as a front-line therapy for multiple myeloma have shown a high response rate and further studies are ongoing. Preclinical studies support the possibility that modulation of proteasome function has great potential as a strategy for chemosensitization. Preliminary clinical trial results suggest that combinations using standard chemotherapeutics with bortezomib may have higher response rates in multiple myeloma than bortezomib as a single agent. Furthermore, these combinations may be able to recapture a response in patients whose disease was previously resistant to the standard agent, or bortezomib, or both. If borne out by additional studies, these results suggest that older treatment paradigms, in which drugs were used once but then discarded from the armamentarium upon disease progression, may need to be reassessed. Bortezomib may provide significant benefits to patients both alone and in combination with other agents and at several time points during the natural history of multiple myeloma.
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PMID:Bortezomib and its role in the management of patients with multiple myeloma. 1505 47

The ubiquitin-proteasome system plays a crucial role in eukaryotic cells in maintaining protein homeostasis. Through the disruption of a variety of pathways and cell cycle checkpoints, proteasome inhibition leads to apoptosis and in experimental models can overcome chemoresistance. Bortezomib is the first of its class of proteasome inhibitors tested in humans that showed promising activity in several tumor types, and especially in hematologic malignancies, in phase I studies. The remarkable results obtained in phase II studies in multiple myeloma (MM) led to its fast-track approval by the US Food and Drug Administration in May 2003 for relapsed MM. More recent observation also revealed promising activity in non-Hodgkin's lymphoma. This review will explore the rationale for the use of bortezomib in hematologic malignancies as well as provide an update on the results of ongoing studies and future directions for the use of this new agent in hematologic malignancies. The mechanism of action of bortezomib and its nonoverlapping toxicity profile make it a very appealing drug for combination with other chemotherapeutic or biologic agents. Bortezomib represents an excellent example of how progress in understanding the biology of cancer cells can impact clinical practice and lead toward a new era of rational therapeutics.
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PMID:Update on the proteasome inhibitor bortezomib in hematologic malignancies. 1507 15

The ubiquitin-proteasome pathway plays a central role in the targeted destruction of cellular proteins, including cell cycle regulatory proteins. Because these pathways are critical for the proliferation and survival of all cells, and in particular cancerous cells, proteasome inhibition is a potentially attractive anticancer therapy. Based on encouraging cytotoxic activity, bortezomib was the first proteasome inhibitor to be evaluated in clinical trials. Efficacy and safety results from a phase 2 clinical trial contributed to approval of bortezomib for use in patients with relapsed and refractory multiple myeloma who have received at least 2 prior therapies and have demonstrated disease progression on their last therapy.
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PMID:The development of proteasome inhibitors as anticancer drugs. 1514 49

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


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