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)

Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis by acting as a potent inducer of vascular permeability as well as serving as a specific endothelial cell mitogen. The importance of angiogenic factors such as VEGF, although clearly established in solid tumors, has not been fully elucidated in human hematopoietic neoplasms. We examined the expression of mRNA and protein for VEGF in 12 human hematopoietic tumor cell lines, representing multiple lineages and diseases, including leukemia, lymphoma, and multiple myeloma. Our results revealed that VEGF message was expressed in these cells and that the corresponding protein was secreted into the extracellular environment. Five of the 12 cell lines were also found to express the Flt-1 receptor for VEGF at a moderate to strong level, suggesting an autocrine pathway. When human vascular endothelial cells were exposed to recombinant human VEGF, there was an increase in the mRNA for several hematopoietic growth factors including macrophage colony-stimulating factor, granulocyte colony-stimulating factor and interleukin 6. Plasma cells in the bone marrow from patients diagnosed with multiple myeloma were found to express VEGF, whereas both the Flt-1 and KDR high affinity VEGF receptors were observed to be markedly elevated in the normal bone marrow myeloid and monocytic cells surrounding the tumor. These data raise the possibility that VEGF may play a role in the growth of hematopoietic neoplasms such as multiple myeloma through either a paracrine or an autocrine mechanism.
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PMID:Expression of vascular endothelial growth factor and its receptors in hematopoietic malignancies. 997 24

Vascular endothelial growth factor (VEGF), a multifunctional cytokine, potently stimulates angiogenesis including tumor neovascularization. Although well established in solid tumors, the role of VEGF in bone marrow neoangiogenesis and paracrine tumor-stromal cell interactions in lymphohematopoietic malignancies has not been fully elucidated. In multiple myeloma (MM), marrow neovascularization parallels disease progression. This parallel prompted us to investigate the expression and secretion of VEGF by myeloma cells and its potential effects in myeloma-marrow stroma interactions. The biologically active splice variants VEGF165 and VEGF121 were expressed and secreted by myeloma cell lines and plasma cells isolated from the marrow of patients with MM. As shown by immunocytochemistry or RT-PCR, myeloma cells did not express or weakly expressed the VEGF receptors FLT-1 and FLK-1/KDR, indicating that autocrine stimulation is unlikely. In contrast, FLK-1/KDR was abundantly expressed by marrow stromal cells. Therefore, we studied the effects of VEGF on marrow stroma, focusing on the secretion of interleukin-6 (IL-6), a potent growth factor for myeloma cells and an inhibitor of plasma cell apoptosis. Exposure of stromal and microvascular endothelial cells to recombinant human (rh) VEGF165 or VEGF121 induced a time- and dose-dependent increase in IL-6 secretion (14- to 27-fold at 50 ng/mL after 24 hours, P <.001). Conversely, rhIL-6 stimulated VEGF expression and secretion in myeloma cell lines (40%-60%; P <.05) and to a variable degree (up to 5.3-fold; P <.005) in plasma cells purified from the marrow of patients with MM. This mutual stimulation suggests paracrine interactions between myeloma and marrow stromal cells triggered by VEGF and IL-6. (Blood. 2000;95:2630-2636)
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PMID:Vascular endothelial growth factor and interleukin-6 in paracrine tumor-stromal cell interactions in multiple myeloma. 1075 44

Vascular endothelial growth factor (VEGF) is a potent angiogenic peptide with biologic effects that include regulation of hematopoietic stem cell development, extracellular matrix remodeling, and inflammatory cytokine generation. The importance of angiogenic factors such as VEGF, while clearly established in solid tumors, has not been fully elucidated in human hematopoietic neoplasms. Human hematopoietic tumor cell lines, representing multiple lineages and diseases, produce and secrete VEGF and express at least one of its two receptors. Exposure of human vascular endothelial cells to VEGF increased the expression of several hematopoietic growth factors known to be involved in myeloma including interleukin-6 (IL-6). Bone marrow samples from patients diagnosed with multiple myeloma were examined for expression of VEGF and its receptors. VEGF protein production was detected in malignant plasma cells from 78% of the myeloma patients studied. While expression of the Flt-1 and KDR receptors was not observed in the malignant plasma cells, both were markedly elevated in the normal marrow myeloid and monocytic cells surrounding the tumor. In bone marrow clot sections from normal allogeneic donors, low-intensity cytoplasmic VEGF expression was detected infrequently in isolated myelocytes, macrophages, and megakaryocytes. In vitro colony-forming assays using patient-derived material revealed that antibody neutralization of VEGF resulted in an inhibition of colony growth, whereas the addition of recombinant human VEGF stimulated colony formation. Neutralization of VEGF activity also suppressed the generation of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) from bone marrow mononuclear cells. These data raise the possibility that VEGF may play a role in the growth of hematopoietic neoplasms such as multiple myeloma through paracrine and perhaps autocrine mechanisms.
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PMID:Expression of vascular endothelial growth factor and its receptors in multiple myeloma and other hematopoietic malignancies. 1174 Aug 8

Our prior studies show that multiple myeloma (MM) cell lines and patient cells express high-affinity vascular endothelial growth factor (VEGF) receptor (VEGFR) Flt-1 but not Flk-1/KDR. Moreover, these studies have shown that VEGF induces proliferation and migration of MM cells, and we have begun to delineate the signaling cascades mediating those sequelae. In this study, we examined the activity of PTK787/ZK 222584 (PTK787), a molecule designed to bind specifically to the tyrosine kinase domain of VEGFR and inhibit angiogenesis. We show that PTK787 acts both directly on MM cells and in the bone marrow microenvironment. Specifically, PTK787 (1-5 micro M) inhibits proliferation of MM cells by 50%, as assayed by [(3)H]thymidine uptake. This effect of PTK787 is dose dependent in both MM cell lines and patient cells that are both sensitive and resistant to conventional therapy. PTK787 enhances the inhibitory effect of dexamethasone on growth of MM cells and can overcome the protective effect of interleukin 6 (IL-6) against dexamethasone-induced apoptosis. PTK787 (1 micro M) also blocks VEGF-induced migration of MM cells across an extracellular matrix. Importantly, PTK787 also inhibits the increased MM cell proliferation and increased IL-6 and VEGF secretion in cultures of MM cells adherent to bone marrow stem cells. These findings therefore demonstrate that PTK787 both acts directly on MM cells and inhibits paracrine IL-6-mediated MM cell growth in the bone marrow milieu. The demonstrated anti-MM activity of PTK787, coupled with its antiangiogenic effects, provides the framework for clinical trials of this agent to overcome drug resistance and improve outcome in MM.
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PMID:The vascular endothelial growth factor receptor tyrosine kinase inhibitor PTK787/ZK222584 inhibits growth and migration of multiple myeloma cells in the bone marrow microenvironment. 1220 56

Angiogenesis or new vessel formation is an essential component in the growth and progression of neoplasms and there is growing evidence of its importance in hematological malignancies including multiple myeloma (MM). Vascular endothelial growth factor (VEGF) is believed to play a role in tumor angiogenesis. We studied the expression of VEGF and its receptors (VEGFR1 or Flt-1 and VEGFR2 or Flk-1/KDR) by myeloma cell lines and plasma cells isolated from patients, using different methods. VEGF expression by the plasma cells was demonstrated by immunohistochemistry in 18 of 20 patients with MM. Enzyme-linked immunosorbent assay demonstrated VEGF secretion in all six different myeloma cell lines studied. Five patient marrow samples and seven different myeloma cell lines were then studied for VEGF mRNA expression by reverse-transcriptase polymerase chain reaction (RT-PCR), which was positive in all. We further evaluated the expression of both VEGFR1 and VEGFR2 in different myeloma cell lines and five sorted myeloma bone marrow samples by RT-PCR. All the myeloma cell lines expressed VEGFR1 and three of the cell lines expressed VEGFR2. VEGFR1 expression was detected in all and VEGFR2 in all but one of the sorted marrow samples. Increased expression of VEGF by the myeloma cells taken in the context of the suspected prognostic value of marrow angiogenesis suggests a pathogenetic role for this cytokine and presence of its receptors on myeloma cells points toward an autocrine mechanism. Demonstration of the presence of VEGFR2 in our study provides a potential biological explanation for the preclinical activity observed with VEGFR2 inhibitors.
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PMID:Expression of VEGF and its receptors by myeloma cells. 1451 53

Previous studies have shown that the multiple myeloma (MM) cell line and MM patient cells express high-affinity vascular endothelial growth factor (VEGF) receptor-1 or Fms-like tyrosine kinase-1 (Flt-1) but not VEGF receptor-2 or Flk-1/kinase insert domain-containing receptor (Flk-1/KDR) and that VEGF triggers MM cell proliferation through a mitogen-activated protein kinase (MAPK)-dependent pathway and migration through a protein kinase C (PKC)-dependent pathway. The present study evaluates the efficacy of the small molecule tyrosine-kinase inhibitor GW654652, which inhibits all 3 VEGF receptors with similar potency. We show that GW654652 acts directly on MM cells and in the bone marrow microenvironment. Specifically, GW654652 (1-10 microg/mL) inhibits, in a dose-dependent fashion, VEGF-triggered migrational activity and cell proliferation of MM cell lines that are sensitive and resistant to conventional therapy. As expected from our previous studies of VEGF-induced signaling and sequelae in MM cells, GW654652 blocked VEGF-induced Flt-1 phosphorylation and downstream activation of AKT-1 and MAPK-signaling cascades. Importantly, GW654652 also inhibits interleukin-6 and VEGF secretion and proliferation of MM cells induced by tumor cell binding to bone marrow (BM) stromal cells. The activity of a pan-VEGF receptor inhibitor against MM cells in the BM milieu, coupled with its lack of major toxicity in preclinical mouse models, provides the framework for clinical trials of this drug class to improve patient outcome in MM.
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PMID:GW654652, the pan-inhibitor of VEGF receptors, blocks the growth and migration of multiple myeloma cells in the bone marrow microenvironment. 1464 94

The expression/function of vascular endothelial growth factor (VEGF) and its receptor 2 (VEGFR-2/KDR) in multiple myeloma (MM)-associated angiogenesis is under scrutiny. We show here that bone marrow endothelial cells (EC) from 16 patients with MM (MMEC) highly expressed VEGF-A (the main VEGF isoform) and VEGFR-2 at both mRNA and protein level, whereas EC from 14 patients with monoclonal gammopathy unassociated/unattributable (MG[u]) (MG[u]EC) and 12 human umbilical veins (HUVEC) expressed very low mRNAs and/or proteins. MMEC showed constitutive autophosphorylation in both VEGFR-2 and the associated extracellular signal-regulated kinase-2 (ERK-2), whereas this was marginal in MG[u]EC and HUVEC. MMEC proliferated rapidly and formed a closely-knit capillary meshwork on Matrigel. These cell functions were reduced in the other EC. Autophosphorylation, proliferation and capillarogenesis were prevented by a neutralizing anti-VEGF-A antibody, and more efficaciously by an anti-VEGFR-2 antibody. Both antibodies had no effect or were poorly effective on the other EC. These findings as a whole suggest the existence of an autocrine loop of VEGF in MMEC. Since this is very likely a mechanism for the amplification of VEGF activity in neovascularization, it would constitute an appropriate target for antiangiogenic management in MM.
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PMID:A VEGF-dependent autocrine loop mediates proliferation and capillarogenesis in bone marrow endothelial cells of patients with multiple myeloma. 1558 54

Angiogenesis governs the progression of multiple myeloma (MM). Circulating endothelial cells (CECs) contribute to angiogenesis and comprise mature ECs and endothelial progenitor cells (EPCs). The present study sought to characterize CECs and their relation to disease activity and therapeutic response in 31 consecutive patients with MM. CECs, identified as CD34(+)/CD146(+)/CD105(+)/CD11b(-) cells, were 6-fold higher in patients compared to controls and correlated positively with serum M protein and beta(2)-microglobulin. Circulating EPCs displayed late colony formation/outgrowth and capillary-like network formation on matrigel; these processes were inhibited after effective thalidomide treatment. Co-expression of vascular endothelial growth factor receptor-2 (KDR) and CD133 characterized EPCs in MM, and KDR mRNA elevations correlated with M protein levels. In vitro exposure of ECs to thalidomide or its derivative CC-5013 inhibited gene expression of the receptors for transforming growth factor-beta and thrombin. Thus, elevated levels of CECs and EPCs covary with disease activity and response to thalidomide, underscoring the angiogenic aspect of MM and suggesting that angioblastlike EPCs are a pathogenic biomarker and a rational treatment target in MM. The results also highlight the anti-angiogenic properties of thalidomide and CC-5013 and further elucidate possible mechanisms of their effectiveness against MM. (Blood. 2005;105:3286-3294).
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PMID:Circulating endothelial progenitor cells in multiple myeloma: implications and significance. 1561 73

The aim of this study was to investigate the fibroblast growth factor receptor 3 (FGFR3) mRNA cleavage by ribozymes targeting FGFR3, effect of growth inhibition and associated with mechanism on multiple myeloma (MM). We designated two ribozyme-expressing plasmids that target the FGFR3 genes, Rz52 and Rz32. In vitro catalytic activity of Rz52 and Rz32 in KMS11 cells decreased FGFR3 mRNA expression to 45% (p < 0.05) and 80% (p < 0.5), respectively, of that of the control. In vivo examination of the Rz52-transfected KMS11 clone showed that FGFR3 mRNA expression decreased to 20% (p < 0.05) of the control. In the Rz52-transfected H929 clone, FGFR3 mRNA decreased to 50% of the control. Protein expression of FGFR3 decreased to 70% of the parental KMS11 and H929 clones. DNA synthesis in the Rz52-transfected KMS11 clone decreased to 20% of that of the control, whereas the viability of cells decreased to 2% (p < 0.01) of that of the control. Ribozyme cleavage-associated increase in apoptosis of Rz52 KMS11 transfectants was twice that of the control. The inhibition of FGFR3 expression by ribozymes was associated with decreased vascular endothelial growth factor (VEGF) expression and upregulation of Flt-1 but not of the KDR receptor. Our data indicate that FGFR3 is an important cell survival and antiapoptotic factor for MM cells and that ribozyme-targeted downregulation of FGFR3 might be useful as a novel therapeutic intervention in MM characterized by t(4;14).
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PMID:Ribozyme cleavage leads to decreased expression of fibroblast growth factor receptor 3 in human multiple myeloma cells, which is associated with apoptosis and downregulation of vascular endothelial growth factor. 1578 96

Protein kinases have emerged as one of the most promising targets for rational drug discovery. In a similar manner to imatinib mesylate (Gleevec), hematological malignancies offer multiple pharmacologic opportunities for manipulation of kinase-induced tumor cell proliferation. Certain kinases have been validated as targets for drug discovery in hematological malignancies (such as BCR-ABL and FLT3); other novel kinases hold considerable interest for targeted intervention: myeloid leukemias (KDR, KIT, CSF-1R, RAS and RAF), lymphoid leukemias (JAK2 fusion protein, TIE-1, CDK modulators), lymphoma (ALK, CDK modulators, mTOR), myeloproliferative disorders (PDGF-R or FGF-R fusion gene products, FGF-R1) and myeloma (FGF-R3, STAT3). Over the past five years, the number of kinase-targeted drug therapies undergoing clinical development has increased exponentially. This review will focus on novel kinase targets currently undergoing preclinical and clinical investigation.
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PMID:Kinases as drug discovery targets in hematologic malignancies. 1630 89


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