UMLS:C0026764 - FACTA Search

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

Angiogenesis plays a significant role in a variety of malignant hematologic diseases, and it is recognized that it has prognostic value. However, the cellular mechanisms by which malignant hematologic cells induce angiogenesis are not well understood. In order to investigate the role of cells from B-cell chronic lymphocytic leukemia (B-CLL) and multiple myeloma (MM) in angiogenesis on human bone marrow endothelial cells (HBMEC), we analyzed the impact of factors secreted by B-CLL cells and by MM cells on HBMEC capillary tube formation on matrigel. It was found that, in addition to the secretion of angiogenic factors VEGF and b-FGF by B-CLL and MM cells, MM cells (but not B-CLL cells) induced a dramatic increase in expression of VEGFR-1 and VEGFR-3 on human bone marrow endothelial cells (HBMEC). It would seem that this increase in VEGFR-3 occurred via the ERK and mTOR pathways, since their respective inhibitors U0126, LY294002 or rapamycin were responsible for a decrease of VEGFR-3. In response to MM cells-increased VEGF receptors on HBMEC, endothelial cell migration was enhanced in a wound artificially produced in a semi-confluent HBMEC culture, a phenomenon which was also down-regulated by the same inhibitors that reversed the increase in VEGF receptors. The present study suggests that, in addition to the classic angiogenic pathway, another mechanism related to an increased expression of VEGFRs on HBMEC might exist in malignant hematopoietic angiogenesis.
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PMID:Malignant hematopoietic cells induce an increased expression of VEGFR-1 and VEGFR-3 on bone marrow endothelial cells via AKT and mTOR signalling pathways. 1695 14

The combined blockade of the IL-6R/STAT3 and the MAPK signaling pathways has been shown to inhibit bone marrow microenvironment (BMM)-mediated survival of multiple myeloma (MM) cells. Here, we identify the molecular chaperones heat shock proteins (Hsp) 90alpha and beta as target genes of both pathways. The siRNA-mediated knockdown of Hsp90 or treatment with the novel Hsp90 inhibitor 17-DMAG attenuated the levels of STAT3 and phospho-ERK and decreased the viability of MM cells. Although knockdown of Hsp90beta-unlike knockdown of Hsp90alpha-was sufficient to induce apoptosis, this effect was strongly increased when both Hsp90s were targeted, indicating a cooperation of both. Given the importance of the BMM for drug resistance and MM-cell survival, apoptosis induced by Hsp90 inhibition was not mitigated in the presence of bone marrow stromal cells, osteoclasts, or endothelial cells. These observations suggest that a positive feedback loop consisting of Hsp90alpha/beta and major signaling pathways supports the survival of MM cells. Finally, in situ overexpression of both Hsp90 proteins was observed in most MMs but not in monoclonal gammopathy of undetermined significance (MGUS) or in normal plasma cells. Our results underpin a role for Hsp90alpha and beta in MM pathogenesis.
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PMID:STAT3 and MAPK signaling maintain overexpression of heat shock proteins 90alpha and beta in multiple myeloma cells, which critically contribute to tumor-cell survival. 1831 31

We discovered that monoclonal antibodies (mAbs) specific to human beta(2)-microglobulin (beta(2)M) induce apoptosis in vitro and were therapeutic in mouse models of myeloma and other hematological tumor cells. Cell death occurred rapidly, without the need for exogenous immunological effector mechanisms. The mAbs induced cell death via recruiting MHC class I molecules to lipid rafts and activating Lyn and PLCgamma2, leading to activated JNK and inhibited PI3K/Akt and ERK, compromised mitochondrial integrity, and caspase-9-dependent cascade activation. Although the expression of beta(2)M on normal hematopoietic cells is a potential safety concern, the mAbs were selective to tumor-transformed cells and did not induce apoptosis of normal cells. Therefore, such mAbs offer the potential for a therapeutic approach to hematological malignancies.
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PMID:Targeting beta2-microglobulin for induction of tumor apoptosis in human hematological malignancies. 1704 7

The mechanisms by which multiple myeloma (MM) cells migrate and home to the bone marrow are not well understood. In this study, we sought to determine the effect of the chemokine SDF-1 (CXCL12) and its receptor CXCR4 on the migration and homing of MM cells. We demonstrated that CXCR4 is differentially expressed at high levels in the peripheral blood and is down-regulated in the bone marrow in response to high levels of SDF-1. SDF-1 induced motility, internalization, and cytoskeletal rearrangement in MM cells evidenced by confocal microscopy. The specific CXCR4 inhibitor AMD3100 and the anti-CXCR4 antibody MAB171 inhibited the migration of MM cells in vitro. CXCR4 knockdown experiments demonstrated that SDF-1-dependent migration was regulated by the P13K and ERK/ MAPK pathways but not by p38 MAPK. In addition, we demonstrated that AMD3100 inhibited the homing of MM cells to the bone marrow niches using in vivo flow cytometry, in vivo confocal microscopy, and whole body bioluminescence imaging. This study, therefore, demonstrates that SDF-1/CXCR4 is a critical regulator of MM homing and that it provides the framework for inhibitors of this pathway to be used in future clinical trials to abrogate MM trafficking.
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PMID:Mechanisms of regulation of CXCR4/SDF-1 (CXCL12)-dependent migration and homing in multiple myeloma. 1711 15

Currently, Arsenic Trioxide (ATO) is considered the treatment of choice for patients with relapsed acute promyelocytic leukemia (APL). Recently, a durable remission with minimal toxicity by single agent ATO or ATO + ATRA in newly diagnosed APL was reported by different groups. These regimens have minimal toxicity and can be administered on an outpatient basis after remission induction, thus they could become a real, less toxic and more economic option to ATRA + anthracyclines in particular in low risk APL, or in patients that cannot undergo chemotherapy because of age or comorbid conditions and in patients that refuse chemotherapy. Significantly, these therapies are a successful attempt to cure a tumoral disease without chemotherapy. The results of clinical trials of ATO administration as single agent in multiple myeloma (MM) and myelodisplastic syndromes (MDS) were encouraging and showed clinical effects but they were not close to APL success. On the contrary, results of clinical trials to treat non-APL acute myeloid leukemia (AML) were disappointing. We suggest that a combination therapy with drugs targeting specific pro-survival molecules or capable to enhance pro-apoptotic pathways may lead to an improvement of ATO efficacy against hematological malignancies, in particular AML. Our pre-clinical studies showed that ATO is capable to induce cell death in acute leukemia cells but the apoptotic function is limited since it can induce also a mechanism of cell defense by activating pro-survival molecules such as MEK-ERK, Bcl-xL, Bcl-2. By combining ATO with specific MEK inhibitors, we demonstrated that the block of MEK-ERK phosphorylation, the induction of Bad de-phosphorylation, and activation of p53AIP1 apoptotic pathway interrupt the pro-survival mechanisms of ATO and kill the leukemic cells by apoptotic synergism. Our results provide an experimental basis for combined or sequential treatment with MEK inhibitors and ATO in AML. The renaissance of ATO as a drug in moderne medicine may be considered, together with ATRA success, a victory of empirical analysis, that had (and has) great impact on Chinese culture.
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PMID:Arsenic trioxide in hematological malignancies: the new discovery of an ancient drug. 1716 55

Multiple myeloma (MM) cells inhibit certain T-cell functions. We examined the expression of B7-H1 (PD-L1), a B7-related protein that inhibits T-cell responses, in CD138-purified plasma cells isolated from MM patients, monoclonal gammopathy of undetermined significance patients, and healthy donors. We observed that B7-H1 was expressed in most MM plasma cells, but not cells isolated from monoclonal gammopathy of undetermined significance or healthy donors. This expression was increased or induced by IFN-gamma and Toll-like receptor (TLR) ligands in isolated MM plasma cells. Blocking the MEK/ERK pathway inhibited IFN-gamma-mediated and TLR-mediated expression of B7-H1. Inhibition of the MyD88 and TRAF6 adaptor proteins of the TLR pathway blocked not only B7-H1 expression induced by TLR ligands but also that mediated by IFN-gamma. IFN-gamma-induced STAT1 activation, via MEK/ERK and MyD88/TRAF6, and inhibition of STAT1 reduced B7-H1 expression. MM plasma cells stimulated with IFN-gamma or TLR ligands inhibited cytotoxic T lymphocytes (CTLs) generation and this immunosuppressive effect was inhibited by preincubation with an anti-B7-H1 antibody, the UO126 MEK inhibitor, or by transfection of a dominant-negative mutant of MyD88. Thus, B7-H1 expression by MM cells represents a possible immune escape mechanism that could be targeted therapeutically through inhibition of MyD88/TRAF6 and MEK/ERK/STAT1.
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PMID:Plasma cells from multiple myeloma patients express B7-H1 (PD-L1) and increase expression after stimulation with IFN-{gamma} and TLR ligands via a MyD88-, TRAF6-, and MEK-dependent pathway. 1736 36

Osteolytic lesions are rapidly progressive during the terminal stages of myeloma, and the bone pain or bone fracture that occurs at these lesions decreases the patients' quality of life to a notable degree. In relation to the etiology of this bone destruction, it has been reported recently that MIP-1alpha, produced in large amounts in myeloma patients, acts indirectly on osteoclastic precursor cells, and activates osteoclasts by way of bone-marrow stromal cells or osteoblasts, although the details of this process remain obscure. In the present study, our group investigated the mechanism by which RANKL expression is induced by MIP-1alpha and the effects of MIP-1alpha on the activation of osteoclasts. RANKL mRNA and RANKL protein expressions increased in both ST2 cells and MC3T3-E1 cells in a MIP-1alpha concentration-dependent manner. RANKL mRNA expression began to increase at 1 h after the addition of MIP-1alpha; the increase became remarkable at 2 h, and continuous expression was observed subsequently. Both ST2 and MC3T3-E1 cells showed similar levels of increased RANKL protein expression at 1, 2, and 3 days after the addition of MIP-1alpha. After the addition of MIP-1alpha, the amount of phosphorylated ERK1/2 and Akt protein expressions showed an increase, as compared to the corresponding amount in the control group. On the other hand, the amount of phosphorylated p38MAPK protein expression showed a decrease from the amount in the control group after the addition of MIP-1alpha. U0126 (a MEK1/2 inhibitor) or LY294002 (a PI3K inhibitor) was added to ST2 and MC3T3-E1 cells, and was found to inhibit RANKL mRNA and RANKL protein expression in these cells. When SB203580, a p38MAPK inhibitor, was added, RANKL mRNA and RANKL protein expression were increased in these cells. MIP-1alpha was found to promote osteoclastic differentiation of C7 cells, an osteoclastic precursor cell line, in a MIP-1alpha concentration-dependent manner. MIP-1alpha promoted differentiation into osteoclasts more extensively in C7 cells incubated together with ST2 and MC3T3-E1 cells than in C7 cells incubated alone. These results suggested that MIP-1alpha directly acts on the osteoclastic precursor cells and induces osteoclastic differentiation. This substance also indirectly induces osteoclastic differentiation through the promotion of RANKL expression in bone-marrow stromal cells and osteoblasts. The findings of this investigation suggested that activation of the MEK/ERK and the PI3K/Akt pathways and inhibition of p38MAPK pathway were involved in RANKL expression induced by MIP-1alpha in bone-marrow stromal cells and osteoblasts. This finding may be useful in the development of an osteoclastic inhibitor that targets intracellular signaling factors.
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PMID:Macrophage inflammatory protein-1alpha (MIP-1alpha) enhances a receptor activator of nuclear factor kappaB ligand (RANKL) expression in mouse bone marrow stromal cells and osteoblasts through MAPK and PI3K/Akt pathways. 1754 7

VEGF (vascular endothelial growth factor), a potent angiogenic molecule specific for vascular endothelial cells, is overexpressed in most tumours including MM (multiple myeloma) and closely associated with tumour growth and prognosis. It has been shown that a soluble fragment of the VEGF receptor Flt-1 (Fms-like tyrosine kinase-1) [sFlt-1 (soluble Flt-1)] has antiangiogenic properties by way of its antagonist activity against VEGF. VEGF and its receptors have been shown to be targets for treating tumours. In the present study, sFlt-1 gene was expressed in Pichia pastoris and the product was applied for studying the effect on KM3 MM cells. sFlt-1 gene was inserted into the pPICZalphaA vector and the expressed product was analysed by SDS/PAGE, immunoblot and ELISA. The sFlt-1 protein was expressed by 0.5% (v/v) methanol induction and it accumulated up to 23% of total proteins in the supernatant. The product was further purified with metal-chelating resin [Ni-NTA (Ni(2+)-nitrilotriacetate)]. The functional analysis of the sFlt-1 protein was performed with HUVEC (human umbilical-vein endothelial cells) proliferation assay. We next showed that the sFlt-1 protein acted directly on MM cells and inhibited the VEGF-induced proliferation of MM cells with MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] and (3)H uptake assay. The sFlt-1 protein blocked VEGF-induced ERK (extracellular-signal-regulated kinase) phosphorylation and inhibited the MAPK (mitogen-activated protein kinase) signalling cascades. The present study demonstrated that anti-MM activity of the sFlt-1 protein, coupled with its antiangiogenic effects, provides the basis for clinical trials of this agent to improve the outcome in MM.
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PMID:Expression of soluble Flt-1 gene in Pichia pastoris and the effect of the product on multiple-myeloma cells in vitro. 1761 89

To better understand the signaling properties of oncogenic FGFR3, we performed phospho-proteomics studies to identify potential downstream signaling effectors that are tyrosine phosphorylated in hematopoietic cells expressing constitutively activated leukemogenic FGFR3 mutants. We found that FGFR3 directly tyrosine phosphorylates the serine/threonine kinase p90RSK2 at Y529, which consequently regulates RSK2 activation by facilitating inactive ERK binding to RSK2 that is required for ERK-dependent phosphorylation and activation of RSK2. Moreover, inhibition of RSK2 by siRNA or a specific RSK inhibitor fmk effectively induced apoptosis in FGFR3-expressing human t(4;14)-positive myeloma cells. Our findings suggest that FGFR3 mediates hematopoietic transformation by activating RSK2 in a two-step fashion, promoting both the ERK-RSK2 interaction and subsequent phosphorylation of RSK2 by ERK.
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PMID:FGFR3 activates RSK2 to mediate hematopoietic transformation through tyrosine phosphorylation of RSK2 and activation of the MEK/ERK pathway. 1778 99

Elevated levels of C-reactive protein (CRP) are present in many disease situations including malignancies and may contribute to the pathogenesis of cardiovascular disorders. This study was undertaken in a myeloma setting to determine whether CRP affects tumor cell growth and survival. We show that CRP enhanced myeloma cell proliferation under stressed conditions and protected myeloma cells from chemotherapy drug-induced apoptosis in vitro and in vivo. CRP binds activating Fcgamma receptors; activates PI3K/Akt, ERK, and NF-kappaB pathways; and inhibits caspase cascade activation induced by chemotherapy drugs. CRP also enhanced myeloma cell secretion of IL-6 and synergized with IL-6 to protect myeloma cells from chemotherapy drug-induced apoptosis. Thus, our results implicate CRP as a potential target for cancer treatment.
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PMID:Human C-reactive protein binds activating Fcgamma receptors and protects myeloma tumor cells from apoptosis. 1778 6

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