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)

The controversial role of interleukin-6 (IL-6) as an auto- or paracrine growth factor for human multiple myeloma (MM) cells was studied using a panel of six well characterized feeder-cell dependent and independent MM cell lines as models. With respect to the effect of IL-6 on growth and survival, three types of lines were found: (1) U-1958, dependent on IL-6 both for growth and survival; (2) U-1996, dependent on IL-6 for growth but not survival; and (3) U-266-1984, Fravel, L363, and Karpas 707, independent of IL-6. Feeder-cell supernatants were as efficient as feeder-cell monolayers in stimulating growth and contained IL-6 as the only growth promoting activity. IL-6 was growth stimulatory and sustained the growth of U-1958 only when the medium contained fetal calf serum. The nature of the serum factor(s) is unknown, but it was excluded to be the IL-6 carrier protein a2-macroglobulin. IL-1, IL-2, IL-3, TNF-alpha, GM-CSF, IGF-1, and insulin were neither co-stimulatory with IL-6 nor stimulated growth on their own. Only U-266-1984 expressed IL-6 mRNA. IL-6 receptor mRNA was expressed in all lines except the L363 and Fravel. We conclude that the response to IL-6 is heterogeneous among the MM lines and that IL-6 acts as a paracrine growth factor for two of six lines. In a third line, U-266-1984, the IL-6 mRNA expression suggests the possibility of an autocrine growth stimulation.
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PMID:Heterogeneity in response to interleukin 6 (IL-6), expression of IL-6 and IL-6 receptor mRNA in a panel of established human multiple myeloma cell lines. 170 69

Monoclonal antibodies were raised against pregnancy-associated endometrial alpha 1-globulin (alpha 1-PEG), a 32 KD insulin-like growth factor binding protein (IGF-BP), which represents a major secretory product of the human decidualized endometrium during pregnancy. This class of IGF-BP has been implicated in the modulation of action, inhibitory and stimulatory, of insulin-like growth factors. Immunization with the protein purified from pregnancy endometrium resulted after myeloma fusion in the isolation of six hybridoma clones and the antibodies produced were characterized. The Ka of the antibodies ranged between 4.75 x 10(9) M-1 and 0.7 x 10(8) M-1. In Western blots all monoclonal antibodies reacted with purified protein of molecular weight 32 KD and specifically detected this IGF-BP species in culture medium and cytosolic extracts of pregnancy endometrium and amniotic fluid. The monoclonal antibodies appear to define three epitope-bearing regions as evidenced by their reactivity to polypeptide fragments of the protein. After synthesis and secretion by tissue explants in vitro the protein is susceptible to cleavage into fragments possessing different monoclonal antibody-defined reactivity. Employing immunohistochemical techniques the protein was principally localized to decidual cells in tissue sections of pregnancy endometrium and solely to these cells after enzymic digestion of the tissue. The implications of these results are discussed with respect to potential role of IGF-BP in the action of IGF upon the IGF-1 receptor-bearing populations, including lymphocytes and trophoblast cells, D in the decidua.
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PMID:Monoclonal antibodies to human secretory "pregnancy-associated endometrial alpha 1-globulin," an insulin-like growth factor binding protein: characterization and use in radioimmunoassay, Western blots, and immunohistochemistry. 248 Jan 40

Peripheral sensory and autonomic neurons are known to possess insulin receptors. These have been considered to be of the peripheral type, i.e. similar to those of hepatic and fat cells rather than of the brain type which show dual specificity for both insulin and insulin-like growth factor (IGF-1). We have examined the localisation of insulin and IGF-1 receptors in cultured sensory and sympathetic ganglion cells using confocal microscopy and indirect labelling with FITC (fluorescein isothiocyanate) and TRITC (tetramethyl rhodamine isothiocyanate) respectively. We have shown that in cultured U266B1 multiple myeloma cells these receptors display separate localisation, whereas they are colocalised in IM-9 lymphocytes which are known to possess hybrid receptors. We have confirmed the sequestration of insulin and IGF-1 receptors in the cytoplasm of sensory and sympathetic neurons, consistent with a brain-type receptor. The colocalisation of insulin and IGF-1 receptors in sensory and sympathetic ganglion cells is consistent with the view that they are hybrid receptors, similar to those present in the CNS. The function of these receptors, as suggested for the CNS, may be related to trophic support for neurons.
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PMID:Colocalisation of insulin and IGF-1 receptors in cultured rat sensory and sympathetic ganglion cells. 941

Osteoporosis is increasingly recognised in men. Low bone mass, risk factors for falling and factors causing fractures in women are likely to cause fractures in men. Bone mass is largely genetically determined, but environmental factors also contribute. Greater muscle strength and physical activity are associated with higher bone mass, while radial bone loss is greater in cigarette smokers or those with a moderate alcohol intake. Sex hormones have important effects on bone physiology. In men, there is no abrupt cessation of testicular function or 'andropause' comparable with the menopause in women; however, both total and free testosterone levels decline with age. A common secondary cause of osteoporosis in men is hypogonadism. There is increasing evidence that estrogens are important in skeletal maintenance in men as well as women. Peripheral aromatisation of androgens to estrogens occurs and osteoblast-like cells can aromatise androgens into estrogens. Human models exist for the effects of estrogens on the male skeleton. In men aged > 65 years, there is a positive association between bone mineral density (BMD) and greater serum estradiol levels at all skeletal sites and a negative association between BMD and testosterone at some sites. It is crucial to exclude pathological causes of osteoporosis, because 30 to 60% of men with vertebral fractures have another illness contributing to bone disease. Glucocorticoid excess (predominantly exogenous) is common. Gastrointestinal disease predisposes patients to bone disease as a result of intestinal malabsorption of calcium and colecalciferol (vitamin D). Hypercalciuria and nephrolithiasis, anticonvulsant drug use, thyrotoxicosis, immobilisation, liver and renal disease, multiple myeloma and systemic mastocytosis have all been associated with osteoporosis in men. It is possible that low-dose estrogen therapy or specific estrogen receptor-modulating drugs might increase BMD in men as well as in women. In the future, parathyroid hormone peptides may be an effective treatment for osteoporosis, particularly in patients in whom other treatments, such as bisphosphonates, have failed. Men with idiopathic osteoporosis have low circulating insulin-like growth factor-1 (IGF-1; somatomedin-1) concentrations, and IGF-1 administration to these men increases bone formation markers more than resorption markers. Studies of changes in BMD with IGF-1 treatment in osteoporotic men and women are underway. Osteoporosis in men will become an increasing worldwide public health problem over the next 20 years, so it is vital that safe and effective therapies for this disabling condition become available. Effective public health measures also need to be established and targeted to men at risk of developing the disease.
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PMID:Osteoporosis in men. New insights into aetiology, pathogenesis, prevention and management. 988 98

The growth factor-dependent myeloma cell line OH-2, which has previously been shown to be responsive to interleukin (IL)-6, tumour necrosis factor (TNF)-alpha and lymphotoxin, was examined for response to other growth factors. Enhanced proliferation was found in the presence of IL-10, IL-15, IL-2 and insulin growth factor (IGF)-1. Proliferation was strongest in response to IL-6, intermediate and roughly equipotent in response to IL-15, IL-10 and TNF-alpha, and modest in response to IL-2 and IGF-1. IL-15 was synergistic with TNF-alpha, whereas combinations of IL-15 and the other cytokines were merely additive. IL-15-induced proliferation could not be blocked by neutralizing antibody against gp 130, the common transducer chain of IL-6 and related cytokines. IL-15 and IL-6 prevented apoptosis equally well, both better than TNF-alpha, IL-10, and IGF-1. In four out of six samples of purified primary cells, IL-15 and IL-6 induced proliferation. Furthermore, IL-15 mRNA was detected by RT-PCR in most myeloma cell lines and freshly isolated purified patient samples. IL-15 protein was detectable only in one out of about 20 tested cell supernatants from patients and myeloma cell lines. The OH-2 cell line is multi-responsive to cytokines and is a good system for the study of integration of cytokine signal transduction and growth control in myeloma. IL-15 represents a novel modality of growth regulation in myeloma.
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PMID:Interleukin-15 blocks apoptosis and induces proliferation of the human myeloma cell line OH-2 and freshly isolated myeloma cells. 1044 59

Several signaling pathways are activated by interferon alpha (IFNalpha) in hematopoietic cells, including the Jak-Stat and the insulin receptor substrate (IRS) pathways. It has been previously shown that IFNalpha activates the phosphatidylinositol (PI) 3'-kinase via an interaction of the p85 subunit of PI 3'-kinase with IRS proteins. Other studies have proposed that Stat-3 also functions as an adapter for p85. We sought to identify the major pathway that regulates IFNalpha activation of the PI3'-kinase in hematopoietic cells. Our data demonstrate that IFNalpha induces the interaction of p85 with IRS-1 or IRS-2, but not Stat-3, in various hematopoietic cell lines in which IRS-1 and/or IRS-2 and Stat-3 are activated by IFNalpha. In addition, inhibition of PI 3'-kinase activity by preincubation of cells with the PI 3'-kinase inhibitor LY294002 does not affect IFN-dependent formation of SIF complexes that contain Stat-3. To determine whether phosphorylation of tyrosine residues in the IFN receptor is required for activation of the PI 3'-kinase, we performed studies using mouse L929 fibroblasts transfected with mutated human IFNAR1 and/or IFNAR2 subunits of the Type I IFN receptor, lacking tyrosine phosphorylation sites. The serine kinase activity of the PI-3K was activated by human IFNalpha in these cells, suggesting that phosphorylation of the Type I IFN receptor is not essential for PI3K activation. We then determined whether IFNalpha activates the Akt kinase, a known downstream target for PI 3'-kinase that mediates anti-apoptotic signals. Akt was activated by insulin or IGF-1, but not IFNalpha, in the IFNalpha-sensitive U-266 myeloma cell line. Altogether, our data establish that the IRS pathway and not the Stat pathway, is the major pathway regulating engagement of PI 3'-kinase in hematopoietic cells. Furthermore, the selective activation of Akt by insulin/IGF-1 suggests the existence of distinct regulatory activities of PI3'-kinase in growth factor versus interferon signaling.
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PMID:Interferon-dependent activation of the serine kinase PI 3'-kinase requires engagement of the IRS pathway but not the Stat pathway. 1073 21

The presence of myeloma cells in the blood circulation. implicates that these cells must have the potential to extravasate and home to the bone marrow environment. Using the 5T2 MM mouse model, we could demonstrate that the restricted localization of myeloma cells in the bone marrow is the result of selective migration of myeloma cells in the bone marrow combined with a selective growth of the tumour cells in the bone marrow microenvironment. Moreover, we showed that 5T2 MM cells bind in vitro selectively to bone marrow-derived endothelial cells (EC) and not to lung-derived EC. In order to identify which chemotactic molecules mediate the transendothelial migration of myeloma cells, we examined the motility-inducing effect of different extracellular matrix proteins on myeloma cell lines. We found that laminin-1 a major component of the basement membrane, triggers the motility of both human myeloma cells and 5T2 MM cells, through the 67 kD laminin receptor. Because of the broad distribution of laminin in extracellular matrices throughout the body, it is clear that this molecule on itself can not be the only factor that determines the specificity of myeloma cell homing. In the 5T2 MM model we identified IGF-1 as a more specific bone marrow derived chemoattractant for myeloma cells. In addition we demonstrated that the marrow microenvironment can upregulate the expression of the IGF-1 receptor on 5T mouse myeloma cells. In the end phase of the disease, increasing numbers of myeloma cells are detectable in the peripheral blood and extramedullary tumour growth can occur. We found that the stroma-independent variant of the human MM5 myeloma cell line showed an increased in vitro motility as compared to the stroma-dependent variant. By representational difference analysis we demonstrated that the stroma-dependent MM5 cells show a downregulation of the motility-related protein (MRP-I CD9) which might reflect the involvement of this molecule in the regulation of myeloma cell extravasation.
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PMID:Homing of the myeloma cell clone. 1114 31

As survival regulation is a key process in multiple myeloma biology, we have studied the Bcl-2 family proteins that can be regulated by three myeloma cell survival factors: interleukin-6 (IL-6), interferon-alpha (IFN-alpha) and insulin-like growth factor (IGF-1). Eleven myeloma cell lines, whose survival and proliferation are dependent on addition of IL-6, variably expressed 10 anti-apoptotic or pro-apoptotic proteins of the Bcl-2-family. When myeloma cells from four cell lines were IL-6 starved and activated with IL-6 or IFN-alpha, we observed that only Mcl-1 expression was up-regulated with myeloma cell survival induction. Nor was obvious regulation of these 10 pro-apoptotic or anti-apoptotic proteins found with IGF-1, another potent myeloma cell survival factor. Our results indicate that the myeloma cell survival activity of IL-6 linked to Bcl-xL regulation cannot be generalized and emphasize that Mcl-1 is the main target of IL-6 and IFN-alpha stimulation. However, other changes in the activity of the Bcl-2 protein family or other apoptosis regulators must be identified to elucidate the IGF-1 action mechanism. Cell Death and Differentiation (2000) 7, 1244 - 1252.
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PMID:Regulation of Bcl-2-family proteins in myeloma cells by three myeloma survival factors: interleukin-6, interferon-alpha and insulin-like growth factor 1. 1117 62

Multiple myeloma (MM) is a plasma cell malignancy preliminary localized in the bone marrow and characterized by its capacity to disseminate. IL-6 and IGF-1 have been shown to mediate proliferative and anti-apoptotic signals in plasmocytes. However, in primary plasma-cell leukemia (PCL) and in end-stage aggressive extramedullar disease, the cytokine requirement for both effects may be not mandatory. This suggests that constitutive activation of signaling pathways occurs. One of the signaling pathways whose deregulation may play an oncogenic role in MM is the phosphatidylinositol 3-kinase (PI 3-K) pathway. In human growth factor-independent MM cell lines OPM2 and RPMI8226, we show that the PI 3-K inhibitors LY294002 and Wortmannin strongly inhibited cell proliferation, whereas inhibition of the mammalian Target Of Rapamycin (mTOR)/P70-S6-kinase (P70(S6K)) pathway with rapamycin or of the Mitogen-Activated Protein Kinase (MAPK) pathway with PD98059 had minimal effect on proliferation. In both cell lines, constitutive activation of the PI 3-K/Akt/FKHRL-1, mTOR/P70(S6K) and MAPK pathways was detected. LY294002 inhibited phosphorylation of Akt, FKHRL-1 and P70(S6K) but had no effect on ERK1/2 phosphorylation, indicating that the PI 3-K and MAPK pathways are independent. IGF-1 but not IL-6 increased phosphorylation of Akt, FKHRL-1 and P70(S6K). Purified plasmocytes from four patients with MM and two patients with primary PCL were studied. In three of them including the two patients with PCL, constitutive phosphorylation of Akt, FKHRL-1 and P70(S6K) was present, inhibited by LY294002 and enhanced by IGF-1. In these patients with constitutive Akt activation, normal PTEN expression was detected. PI 3-K inhibition induced caspase-dependent apoptosis as confirmed by inhibition with the large spectrum caspase inhibitor Z-VAD-FMK and cleavage of pro-caspase-3. Both cell lines spontaneously expressed Skp2 and cyclin D1 proteins at high levels but no p27(Kip1) protein. In the presence of LY294002, cell-cycle arrest in G0/G1 was observed, p27(Kip1) protein expression was up-regulated whereas the expression of both Skp2 and cyclin D1 dramatically diminished. PI 3-K-dependent GSK-3alpha/beta constitutive phosphorylation was also detected in OPM2 cells that may contribute to high cyclin D1 expression. Overall, our results suggest that PI 3-K has a major role in the control of proliferation and apoptosis of growth factor-independent MM cell lines. Most of the biological effects of PI 3-K activation in these cell lines may be mediated by the opposite modulation of p27(Kip1) and Skp2 protein expression. Moreover, constitutive activation of this pathway is a frequent event in the biology of MM in vivo and may be more frequently observed in PCL.
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PMID:Role of the phosphatidylinositol 3-kinase/Akt and mTOR/P70S6-kinase pathways in the proliferation and apoptosis in multiple myeloma. 1224 56

The proteasome inhibitor PS-341 inhibits IkappaB degradation, prevents NF-kappaB activation, and induces apoptosis in several types of cancer cells, including chemoresistant multiple myeloma (MM) cells. PS-341 has marked clinical activity even in the setting of relapsed refractory MM. However, PS-341-induced apoptotic cascade(s) are not yet fully defined. By using gene expression profiling, we characterized the molecular sequelae of PS-341 treatment in MM cells and further focused on molecular pathways responsible for the anticancer actions of this promising agent. The transcriptional profile of PS-341-treated cells involved down-regulation of growth/survival signaling pathways, and up-regulation of molecules implicated in proapoptotic cascades (which are both consistent with the proapoptotic effect of proteasome inhibition), as well as up-regulation of heat-shock proteins and ubiquitin/proteasome pathway members (which can correspond to stress responses against proteasome inhibition). Further studies on these pathways showed that PS-341 decreases the levels of several antiapoptotic proteins and triggers a dual apoptotic pathway of mitochondrial cytochrome c release and caspase-9 activation, as well as activation of Jun kinase and a Fas/caspase-8-dependent apoptotic pathway [which is inhibited by a dominant negative (decoy) Fas construct]. Stimulation with IGF-1, as well as overexpression of Bcl-2 or constitutively active Akt in MM cells also modestly attenuates PS-341-induced cell death, whereas inhibitors of the BH3 domain of Bcl-2 family members or the heat-shock protein 90 enhance tumor cell sensitivity to proteasome inhibition. These data provide both insight into the molecular mechanisms of antitumor activity of PS-341 and the rationale for future clinical trials of PS-341, in combination with conventional and novel therapies, to improve patient outcome in MM.
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PMID:Molecular sequelae of proteasome inhibition in human multiple myeloma cells. 1239 22

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