Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0026764 (multiple myeloma)
36,148 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bortezomib, a proteasome inhibitor, shows substantial anti-tumor activity in a variety of tumor cell lines, is in phase I, II, and III clinical trials and has recently been approved for the treatment of patients with multiple myeloma. The sequence of events leading to apoptosis following proteasome inhibition by bortezomib is unclear. Bortezomib effects on components of the mitochondrial apoptotic pathway were examined: generation of reactive oxygen species (ROS), alteration in the mitochondrial membrane potential (Delta psi m), and release of cytochrome c from mitochondria. With human H460 lung cancer cells, bortezomib exposure at 0.1 microM showed induction of apoptotic cell death starting at 24 h, with increasing effects after 48-72 h of treatment. After 3-6 h, an elevation in ROS generation, an increase in Delta psi m, and the release of cytochrome c into the cytosol, were observed in a time-dependent manner. Co-incubation with rotenone and antimycin A, inhibitors of mitochondrial electron transport chain complexes I and III, or with cyclosporine A, an inhibitor of mitochondrial permeability transition pore, resulted in inhibition of bortezomib-induced ROS generation, increase in Delta psi m, and cytochrome c release. Tiron, an antioxidant agent, blocked the bortezomib-induced ROS production, Delta psi m increase, and cytochrome c release. Tiron treatment also protected against the bortezomib-induced PARP protein cleavage and cell death. Benzyloxycarbonyl-VAD-fluoromethyl ketone, an inhibitor of pan-caspase, did not alter the bortezomib-induced ROS generation and increase in Delta psi m, although it prevented bortezomib-induced poly(ADP-ribose) polymerase cleavage and apoptotic death. In PC-3 prostate carcinoma cells (with overexpression of Bcl-2), a reduction of bortezomib-induced ROS generation, Delta psi m increase was correlated with cellular resistance to bortezomib and the attenuation of drug-induced apoptosis. The transient transfection of wild type p53 in p53 null H358 cells caused stimulation of the bortezomib-induced apoptosis but failed to enhance ROS generation and Delta psi m increase. Thus ROS generation plays a critical role in the initiation of the bortezomib-induced apoptotic cascade by mediation of the disruption of Delta psi m and the release of cytochrome c from mitochondria.
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PMID:Reactive oxygen species generation and mitochondrial dysfunction in the apoptotic response to Bortezomib, a novel proteasome inhibitor, in human H460 non-small cell lung cancer cells. 1282 77

These studies explore the molecular effect of arsenicals on MM cells. Freshly isolated cells derived from patients with advanced, chemo-refractory myeloma as well as human myeloma cell lines, ARP-1, RPMI-8226 and H929 were exposed to the organic arsenical melarsoprol and to the inorganic compound AT. Both agents potently induced apoptosis in myeloma cells. Exposure to 1-5 microM AT or melarsoprol for 6 hours suppressed NF-kappa B DNA binding and enhanced of c-Jun kinase (JNK) activity. Arsenic also activated caspase-3 resulting in the cleavage of poly (ADP-ribose) polymerase (PARP) and Fas/TNF alpha related receptor interacting protein (RIP). In contrast to reported observations in acute promyelocytic leukemia, myeloma cell apoptosis was not associated with either the downregulation of Bcl-2 protein or with alterations in the expression of other Bcl-2 family members, Bax, Bak, Bag, and Bcl-xl. This study first shows that arsenic induces apoptotic signaling in MM through the cleavage of TNF alpha related receptor interacting protein (RIP). RIP is a key downstream protein in FasL/ TNF alpha /TRAIL induced apoptosis and a major antiapoptotic adaptor of pathways through NF-kappa B and JNK. RIP has not been previously characterized in myeloma. This study supports the hypothesis that arsenicals share common mediators (RIP, NF-kappa B, PARP, caspase-3) with death receptor induced apoptosis. These studies provide an important insight into the molecular mechanism of AT induced apoptosis and can be used in the development of adjuvant therapy for MM, presently an incurable disease.
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PMID:RIP kinase is involved in arsenic-induced apoptosis in multiple myeloma cells. 1531 84

Myeloid cell leukemia-1 (MCL-1) acts as a key survival factor for chronic lymphocytic leukemia (CLL) cells. In addition, dissipation of cellular bioenergy may impose a lethal effect on these quiescent cells. Previously, in multiple myeloma cell lines we demonstrated that halogenated adenosine (8-Cl-Ado) was phosphorylated to triphosphate (8-Cl-adenosine triphosphate [ATP]), which preferentially incorporated into mRNA and inhibited RNA synthesis by premature transcription termination. Furthermore, 8-Cl-ATP accumulation was associated with a decline in cellular bioenergy. Based on these actions, we hypothesized that 8-Cl-Ado would be ideal to target CLL lymphocytes. In the present study we demonstrate that leukemic lymphocytes incubated with 8-Cl-Ado display time- and dose-dependent increase in the accumulation of 8-Cl-ATP, with a parallel depletion of the endogenous ATP pool. Inhibition of global RNA synthesis resulted in a significant decline in the expression of transcripts with a short half-life such as MCL1. Consistent to this, protein expression of MCL-1 but not B-cell lymphoma-2 (BCL-2) was decreased. Furthermore, 8-Cl-ATP induced programmed cell death, as suggested by caspases activation, cleavage of caspase 3, and PARP (poly-adenosine diphosphate [ADP]-ribose polymerase), and increased DNA fragmentation. In conclusion, 8-Cl-Ado induces apoptosis in CLL lymphocytes by targeting cellular bioenergy as well as RNA transcription and translation of key survival genes such as MCL1.
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PMID:Cell death of bioenergetically compromised and transcriptionally challenged CLL lymphocytes by chlorinated ATP. 1571 23

In this study we report that R-etodolac (SDX-101), at clinically relevant concentrations, induces potent cytotoxicity in drug-sensitive multiple myeloma (MM) cell lines, as well as in dexamethasone (MM.1R)-, doxorubicin (Dox40/RPMI8226)-, and bortezomib (DHL4)-resistant cell lines. Immunoblot analysis demonstrates that R-etodolac induces apoptosis characterized by caspase-8, -9, and -3 and PARP (poly-ADP [adenosine diphosphate]-ribose polymerase) cleavage and down-regulation of cyclin D1 expression. Subcytotoxic doses of R-etodolac up-regulate myeloid cell leukemia-1 proapoptotic variant (Mcl-1S), while enhancing dexamethasone (Dex)-induced caspase activation and apoptosis. The combination of R-etodolac with Dex results in a highly synergistic cytotoxic effect. R-etodolac also induces apoptosis against primary cells isolated from patients with MM refractory to chemotherapy. Although interleukin 6 (IL-6) and insulin-like growth factor-1 (IGF-1) abrogate Dex-induced MM cell cytotoxicity, neither IL-6 nor IGF-1 protects against R-etodolac-induced cytotoxicity in MM cells. R-etodolac also inhibits viability of MM cells adherent to bone marrow stromal cells (BMSCs), thereby overcoming a mechanism of drug resistance commonly observed with other conventional chemotherapeutic agents. Our data, therefore, indicate that R-etodolac circumvents drug resistance in MM cells at clinically relevant concentrations, targets Mcl-1, and can be synergistically combined with Dex.
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PMID:SDX-101, the R-enantiomer of etodolac, induces cytotoxicity, overcomes drug resistance, and enhances the activity of dexamethasone in multiple myeloma. 1580 27

Thalidomide alone or in combination with steroids has significant activity in multiple myeloma (MM). However, given its teratogenic potential, analogs have been synthesized, retaining the anti-MM activity without these side effects. We examined the anti-MM activity of two thalidomide analogs, CPS11 and CPS49. Direct cytotoxicity of the drugs on myeloma cell lines and patient myeloma cells was examined using thymidine uptake. Tumor cell apoptosis was evaluated by flow cytometry as well as Western blotting for caspase and PARP cleavage. Cellular signaling events were examined by immunoblotting for phosphorylated proteins. Both drugs inhibit proliferation of several MM cell lines sensitive and resistant to conventional therapies. They decrease secretion of IL-6, IGF, and VEGF by marrow stromal cells. Importantly, they inhibit proliferation of MM cells adherent to stromal cells. These drugs induce caspase-mediated apoptosis in MM cell lines, as well as patient MM cells. They inhibit the PI3K/Akt and JAK/STAT (signal transducers and activators of transcription) pathways in MM cells and are antiangiogenic in matrigel-based assays. CPS11 and CPS49 have potent antimyeloma activity and can overcome protective effects of the tumor microenvironment. They have potent antiangiogenic activity and direct effect on bone marrow stroma. These encouraging preclinical data provide the basis for further evaluation in the clinic.
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PMID:Antimyeloma activity of two novel N-substituted and tetraflourinated thalidomide analogs. 1585 15

Multiple myeloma is a clonal malignancy of plasma cells that invariably progresses to a chemoresistant state. The PI3K/Akt pathway mediates signals downstream of several growth factors involved in myeloma pathogenesis, and constitutive activation of Akt was observed in myeloma cells. We now report that a staurosporine derivative, N-benzoylated staurosporine or PKC412, induces cell death in myeloma cell lines (RPMI8226S, U266, MM1S and MM1R) with loss of mitochondrial membrane potential Delta psi m, caspase 3 and PARP cleavage. ZVAD.fmk, but not interleukin-6, rescued these cells from PKC412 effects. Upstream of the mitochondria, PKC412 inhibited Bad phosphorylation and attenuated Akt kinase activity by suppressing its phosphorylation on serine residue in its activation loop. Reduced phosphorylation of downstream Akt substrates GSK3 alpha/beta and FKHR was also noted. Stable transfection of 8226S cells with constitutively active Akt (8226S-myAkt) partially protected against PKC412 cytotoxicity. Primary myeloma cells isolated from refractory myeloma patients (n=4), were equally sensitive to PKC412 treatment. More importantly, PKC412 did not affect CFU-GM or BFU-E colony formation. In summary, our results demonstrate that PKC412 suppresses Akt kinase activation and induces apoptosis in myeloma cell lines, as well as primary resistant cells. PKC412 is an appropriate candidate for novel treatment protocols for multiple myeloma.
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PMID:N-benzoylstaurosporine (PKC412) inhibits Akt kinase inducing apoptosis in multiple myeloma cells. 1601 36

Histone deacetylase (HDAC) inhibitors have shown cytotoxicity as single agents in preclinical studies for multiple myeloma (MM) cells. LBH589 is a novel hydroxamic acid derivative that at low nanomolar concentrations induces apoptosis in MM cells resistant to conventional therapies via caspase activation and poly-(ADP-ribose) polymerase (PARP) cleavage. Significant synergistic cytotoxicity was observed with LBH589 in combination with bortezomib against MM cells that were sensitive and resistant to dexamethasone (Dex), as well as primary patient MM cells. LBH589 at low nanomolar concentrations also induced alpha-tubulin hyperacetylation. Aggresome formation was observed in the presence of bortezomib, and the combination of LBH589 plus bortezomib induced the formation of abnormal bundles of hyeracetylated alpha-tubulin but with diminished aggresome size and apoptotic nuclei. These data confirm the potential clinical benefit of combining HDAC inhibitors with proteasome inhibitors, and provide insight into the mechanisms of synergistic anti-MM activity of bortezomib in combination with LBH589.
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PMID:Aggresome induction by proteasome inhibitor bortezomib and alpha-tubulin hyperacetylation by tubulin deacetylase (TDAC) inhibitor LBH589 are synergistic in myeloma cells. 1672 95

In studies of multiple myeloma cells, atiprimod was shown to block Stat3 activation and inhibited colony-forming cell proliferation. We hypothesized that atiprimod may also inhibit activation of intracellular signaling pathways in AML cells resulting in apoptosis and growth inhibition. We demonstrate that atiprimod inhibited clonogenic growth of AML cell lines and fresh AML marrow cells whereas it did not significantly affect growth of normal hematopoietic progenitors from marrow samples of healthy controls. Atiprimod decreased phosphorylation of Stat3 and Stat5, and protein levels of Jak2, whereas gene expression of Jak2 was not affected. Atiprimod further induced apoptosis by cleavage of caspase 3 and PARP. In summary, our data suggest that atiprimod has a significant antiproliferative and proapoptotic effect on AML cells. This effect may be facilitated by inhibition of the Jak-Stat signaling pathway. Further evaluation of atiprimod in clinical trials of AML should be considered.
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PMID:Atiprimod blocks phosphorylation of JAK-STAT and inhibits proliferation of acute myeloid leukemia (AML) cells. 1682 65

Studies in our laboratory demonstrate that vitamin D (1,25 dihydroxycholecalciferol or calcitriol) has significant antitumor activity in vitro and in vivo in murine and human squamous cell, prostate, lung, pancreatic and myeloma model systems. Calcitriol induces G0/G1 arrest, modulates p27 and p21, the cyclin-dependent kinase (cdk) inhibitors implicated in G1 arrest, and induces cleavage of caspase 3, PARP and the mitogen-activated protein kinase (MEK) in a caspase-dependent manner. Calcitriol also decreases phospho-Erk (P-Erk) and phospho-Akt (P-Akt), kinases that regulate cell survival pathways and up-regulate the pro-apoptotic signaling molecule, MEKK-1. Glucocorticoids enhance calcitriol-mediated activities pre-clinically in vitro and in vivo. Dexamethasone (dex) significantly potentiated the antitumor effect of calcitriol and decreased calcitriol-induced hypercalcemia. Both in vitro and in vivo, dex increased vitamin D receptor (VDR) ligand binding in the tumor while decreasing binding in intestinal mucosa, the site of calcium absorption. These studies demonstrated that calcitriol has significant antiproliferative activity in a number of pre-clinical model systems and form the groundwork for on-going clinical studies investigating calcitriol as an anticancer agent.
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PMID:The antitumor efficacy of calcitriol: preclinical studies. 1688 62

The effect and mode of action of the protein kinase C (PKC) inhibitor PKC412 on human multiple myeloma (MM) cell lines (HMCLs) and primary MM cells was explored. We found that PKC412 induced apoptosis of HMCLs and primary MM cells with variable efficacy; however, some activity was seen against all HMCLs and primary MM cells with at least 0.5 microM PKC412. PARP cleavage and decreased PKC activity was observed in all HMCLs tested. Furthermore, PKC412 inhibited C-FOS transcription and nuclear protein expression, induced reactive oxygen species (ROS) production, and induced both sustained C-JUN expression and phosphorylation. The latter was inhibited by cotreatment with the JNK inhibitor SP600125, which similarly abrogated PKC412-induced apoptosis, suggesting that PKC412-induced apoptosis is a JNK-dependent event. PKC412 treatment secondarily induced prosurvival stress responses as evidenced by activation of NFkappaB and increased expression of the heat shock proteins HSP70 and HSP90. Consistent with the former, sequential inhibition of NFkappaB activation with bortezomib or SN50 synergistically enhanced cell killing. Our results demonstrate that PKC412 induces JNK-dependent apoptosis of HMCLs and primary MM cells and that this effect is enhanced by NFkappaB inhibition. The further evaluation of PKC412 in the treatment of MM is justified.
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PMID:PKC412 demonstrates JNK-dependent activity against human multiple myeloma cells. 1703 22


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