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)

Multiple myeloma (MM) is a B cell malignancy characterized by the expansion of monoclonal Ig-secreting plasma cells with low proliferative activity. It is postulated that inhibition of physiologic cell death is an underlying factor in the pathophysiology of MM. The development of chemoresistance is a common feature in patients with MM. In the present studies, hexamethylene bisacetamide (HMBA), a hybrid polar compound that is a potent inducer of terminal differentiation of various transformed cells, is shown to inhibit the growth of several human myeloma cell lines (ARP-1, U266, and RPMI 8226), including doxorubicin-resistant RPMI 8226 variants that overexpress the multidrug-resistance gene, MDR-1, and its product, p-glycoprotein. In addition to growth arrest and suppression of clonogenicity, HMBA induces apoptosis both in freshly isolated human myeloma cells and in cell lines, as determined by morphologic alterations, cell cycle distribution and endonucleosomal DNA fragmentation. Further, HMBA decreases BCL-2 protein expression in myeloma cells within 12-48 hr. Overexpression of BCL-2 protein in ARP-1 cells confers resistance to HMBA-induced apoptosis. Taken together, these data suggest that HMBA is a potent inducer of apoptosis in human myeloma cells, which may act through suppressing the anti-apoptotic function of the bcl-2 gene. HMBA, and related hybrid polar compounds, may prove useful in the management of this presently incurable disease.
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PMID:Hexamethylene bisacetamide induces programmed cell death (apoptosis) and down-regulates BCL-2 expression in human myeloma cells. 941 46

Eight myeloma cell lines with variable expression of bcl-2 were screened for the expression of the FAS antigen and for sensitivity to anti-FAS-induced apoptosis. Anti-FAS-induced apoptosis correlated positively (R = 0.89) with the level of expression of the FAS antigen, and was independent of the expression of bcl-2. Forced expression of bcl-2 in 8226 and ARP-1 multiple myeloma (MM) cell lines expressing relatively low levels of bcl-2, resulted in 1-2 log increase in resistance to dexamethasone (DEX)-induced apoptosis. However, sensitivity to anti-FAS-induced apoptosis was unchanged in ARP-1 cells or was increased in 8226 cells, compared to the parental cell lines. The increased sensitivity to anti-FAS-induced apoptosis in 8226 cells was due to the increase in FAS expression in the bcl-2 transfected cells and was proportionate to the increase in FAS expression. Furthermore, we observed manyfold increase in the expression of Fas, CD40, CD45 and CD19 antigens, in 8226 cells, concomitant with a significant decrease in the expression of CD38 antigen. Thus, 8226 cells overexpressing bcl-2 appear to have an immature myeloma cell phenotype, have higher growth-rate and increased sensitivity to anti-FAS-induced apoptosis.
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PMID:Fas (APO-1/CD95)-mediated apoptosis is independent of bcl-2: a study with cell lines overexpressing bcl-2 and with bcl-2 transfected cell lines. 945 7

Multiple myeloma (MM) is an incurable disease despite an initial response-rate of >60% with conventional or high-dose chemotherapy. Glucocorticosteroids such as dexamethasone (DEX) and alkylating agents such as melphalan (MEL) are capable of inducing complete responses (CR) in >50% of MM patients, however, resistance to these drugs develop rapidly, in >90% of patients, within 2 years of treatment. The exact mechanism of resistance to these drugs is not known. We investigated the mechanism of resistance to DEX and MEL. In particular, we investigated the role of bcl-2 in development of resistance to these two drugs. We tested the role of bcl-2 by transfecting 2 low bcl-2-expressing myeloma cell lines, ARP-1 and 8226, with a bcl-2 expression vector and compared the effects of DEX and MEL on apoptosis, cell cycle distribution and the levels of proapoptotic (bax) and antiapoptotic (bcl-2, bclx) proteins. The results indicate that the two drugs act by a different mechanism with respect to all the parameters tested. While DEX-induced apoptosis was dependent on the level of bcl-2 expression, MEL-induced apoptosis was independent of bcl-2 levels. Treatment with DEX of the low bcl-2-expressing cells (DEX-sensitive) resulted in a rapid apoptosis from all phases of the cell cycle. In contrast, treatment with MEL blocked the cells in late-S/G2 phase of the cell cycle and caused substantial apoptosis, regardless of bcl-2 expression. Major differences between DEX and MEL were also observed with respect to their effects on the levels of bcl-2 and p53. Whereas DEX induced an early (day 1) downregulation of bcl-2 (only in the cells with low bcl-2), treatment with MEL did not affect bcl-2 levels. The levels of bclx and bax remained unchanged following treatment with either MEL or DEX. These results, taken together, suggest that the two drugs target different cellular components and induce apoptosis by different pathways, and that resistance to DEX is associated with low levels of bcl-2, whereas resistance to MEL is independent of bcl-2, and therefore, in vivo resistance to MEL, observed in MM patients, might involve other mechanisms rather than bcl-2.
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PMID:Bcl-2 overexpression is associated with resistance to dexamethasone, but not melphalan, in multiple myeloma cells. 966 39

The molecular mechanisms by which multiple myeloma (MM) cells evade glucocorticoid-induced apoptosis have not been delineated. Using a human IgAkappa MM cell line (ARP-1), we found that dexamethasone (Dex)-induced apoptosis is associated with decreased NF-kappaB DNA binding and kappaB-dependent transcription. Both nuclear p50:p50 and p50:p65 NF-kappaB complexes are detected in ARP-1 cells by supershift electrophoretic mobility shift assay (EMSA). Dex-mediated inhibition of NF-kappaB DNA binding precedes a notable increase in annexin V binding, thereby indicating that diminished NF-kappaB activity is an early event in Dex-induced apoptosis. Overexpression of bcl-2 in ARP-1 cells prevents Dex-mediated repression of NF-kappaB activity and apoptosis. Sustained NF-kappaB DNA binding is also observed in two previously characterized Dex-resistant MM cell lines (RPMI8226 and ARH-77) that express moderate levels of endogenous bcl-2 and IkappaBalpha proteins. In addition, enforced bcl-2 expression in ARP-1 cells did not prevent the augmentation of IkappaBalpha protein by Dex. We also noted a possible association between Dex-mediated downregulation of NF-kappaB in freshly obtained primary myeloma cells and the patients' responsiveness to glucocorticoid-based chemotherapy. Collectively, our data suggest that the protective effects of bcl-2 in MM cells act upstream in the NF-kappaB activation-signaling pathway and the potential use of NF-kappaB as a biomarker in progressive MM.
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PMID:Role of NF-kappaB in the rescue of multiple myeloma cells from glucocorticoid-induced apoptosis by bcl-2. 1021 1

TRAIL, the ligand for the newly discovered DR-4 and DR-5 receptor, is a member of the TNF family of death signal transduction proteins with a mechanism of cell death similar to that of Fas and Fas ligand (Fas-L) system. We provide first time evidence that TRAIL is a potent inducer of apoptosis in multiple myeloma (MM) cell lines. TRAIL effectively induced extensive apoptosis in 8226 and ARP-1 MM cells in a time- and dose-dependent manner. Apoptosis with TRAIL reached about 80% within 48 h of treatment with a dose of 160 ng/ml. Furthermore, we provide first time evidence that similar to Fas, TRAIL-induced apoptosis is not blocked by bcl-2 in MM cell lines. Most importantly, TRAIL induced substantial apoptosis in freshly isolated, flow-sorted myeloma cells obtained from different MM patients expressing variable levels of bcl-2. Finally, we demonstrate for the first time that TRAIL is not cytotoxic to purified CD34+/CD45dim hematopoietic stem cells and does not inhibit CFU-GM or BFU-E colony formation in methylcellulose.
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PMID:TRAIL is a potent inducer of apoptosis in myeloma cells derived from multiple myeloma patients and is not cytotoxic to hematopoietic stem cells. 1055 57

TRAIL, the ligand for the newly discovered DR-4 and DR-5 receptor is a member of the tumour necrosis factor (TNF) family of death signal tranduction proteins with a mechanism of cell death, similar to the Fas and Fas ligand (Fas-L) system. Here, we provide first time evidence that TRAIL and TNF-alpha are potent inducers of apoptosis in multiple myeloma (MM) cell lines and freshly isolated myeloma cells. TRAIL effectively induced extensive apoptosis in 8226 and ARP-1 MM cells in a time- and dose-dependent manner reaching 80% within 48 h of treatment with a dose of 160 ng/ml. Bcl-2 transfected 8226 and ARP-1 cells were equally sensitive to apoptosis by TRAIL. Apoptosis with TNFalpha, reached >60% within 48 h of treatment with a dose of 160 ng/ml. In addition to MM cell lines, freshly isolated, flow-sorted myeloma cells from 8 different MM patients expressing variable levels of bcl-2 were equally sensitive to both TRAIL and TNF-alpha. We have previously shown that anti-Fas-induced apoptosis is not blocked by endogenous or ectopic bcl-2 in MM cell lines. Here we extend our observation with Fas to include TNF-alpha and TRAIL to the apoptotic signals that are not be blocked by bcl-2, in MM cells.
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PMID:Apoptosis-induced by TRAIL AND TNF-alpha in human multiple myeloma cells is not blocked by BCL-2. 1062 26

Accumulating evidence indicates that a graft-vs.-myeloma effect (GVM) and its associated clinical remission of the disease can be induced by donor lymphocyte infusion in myeloma patients who have relapsed after allogeneic bone marrow transplantation. Although it is believed that GVM is induced by allospecific T cells, T-cell subsets and the mechanisms involved in the killing of myeloma cells by donor T cells have not been studied. In this study, we generated allospecific cytotoxic T lymphocyte (CTL) lines against three different myeloma cell lines, ARK, ARP-1 and U266, from unmatched healthy donors and examined their cytotoxicity against the target cells. Our results demonstrate that the allospecific CTLs efficiently lysed myeloma cells. The observed cytotoxicity was mediated mainly by CD8+ T cells and inhibited by MHC class I-blocking antibody. Furthermore, the CTLs lysed the target cells via the perforin-mediated pathway, as concanamycin A, but not brefeldin A (the selective inhibitors for perforin- or Fas-mediated pathways respectively) or tumour necrosis factor-alpha (TNF-alpha)-blocking antibody, abrogated the cytolytic activity of the cells. These CTLs expressed and produced predominantly TNF-alpha and interferon-gamma (IFN-gamma), indicating that they belong to the type 1 T-cell subsets. Taken together, these results indicate that CD8+ allospecific T cells may be responsible for mediating GVM and that the granule-mediated lysis of target cells is the major pathway in the CD8+ T-cell response against myeloma cells.
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PMID:Myeloma-reactive allospecific cytotoxic T lymphocytes lyse target cells via the granule exocytosis pathway. 1116 40

High beta(2)-microglobulin (beta(2)m) levels in myeloma correlate with poor prognosis. We hypothesized that beta(2)m may affect myeloma cell growth and survival. In this study, we examined the in vitro effects of beta(2)m on myeloma cells. Primary myeloma cells freshly isolated from patients and myeloma cell lines were used, cultured in the presence of beta(2)m, and monitored for growth and survival. Beta(2)m suppressed the growth of primary tumour cells and myeloma cell lines (ARK-RS, ARP-1, RPMI-8226, U266, ARH-77 and IM-9). High concentrations of beta(2)m induced apoptosis and cell cycle arrest. Beta(2)m-induced apoptosis was dependent on activation of a caspase cascade, inhibited by interleukin 6, and did not involve the surface death receptors, as receptor-neutralizing antibodies had no inhibitory effect. Beta(2)m-induced growth arrest was associated with downregulation of cyclins A and D2. Surprisingly, anti-beta(2)m antibodies did not block the effect of beta(2)m but were synergistic with beta(2)m, resulting in 90% growth inhibition and 70% apoptosis of myeloma cells. Whereas beta(2)m treatment resulted in slight upregulation of surface beta(2)m and major histocompatibility complex class I alpha-chain expression, treatment of myeloma cells with anti-beta(2)m antibodies alone or with beta(2)m resulted in significant downregulation of surface beta(2)m and class I molecules, suggesting that class I molecules may be involved in signal transduction. Our data demonstrate that beta(2)m plays an important role in regulating the growth and survival of myeloma cells in vitro and warrants further investigation to delineate the mechanisms of beta(2)m and anti-beta(2)m antibody-induced growth regulation of myeloma cells.
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PMID:Beta(2)-microglobulin as a negative growth regulator of myeloma cells. 1213 38

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

The mechanisms underlying sperm protein 17 (Sp17) gene expression in myeloma cells remained unclear. Using reverse transcription-polymerase chain reaction (RT-PCR), Sp17 transcripts were detected in ARK-B, ARP-1, RPMI-8226 and KMS-11 but not in H929, IM-9, MM1-R and U266 cells. Using a panel of primer pairs in methylation-sensitive PCR to amplify overlapping gene segments, our screening studies showed that the HpaII sites at -359 and -350 are involved in the regulation of Sp17 gene expression. To confirm the differences in methylation status between Sp17-positive and Sp17-negative cell lines, KMS-11 cells (Sp17-positive) and IM-9 cells (Sp17-negative) were subjected to the more accurate method of bisulphite conversion. KMS-11 cells were more hypomethylated at these HpaII sites of exon 1 compared to IM-9 cells, indicating the association of hypomethylated promoter with Sp17 gene expression. In addition, the level of methylation at other CpG sites within the promoter sequence was also higher in IM-9 than KMS-11. Exon 1 was cloned into a reporter vector, pCAT*3 Enhancer. Chloramphenicol acetyl transferase (CAT) activity was restored in cells transfected with the recombinant plasmid, indicating the promoter function of exon 1. Exposure of Sp17-negative cell lines to the hypomethylating agent, 5-azacytidine, resulted in the upregulation of Sp17 gene expression. Our results therefore provide evidence for the regulation of Sp17 gene expression by promoter methylation.
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PMID:Sp17 gene expression in myeloma cells is regulated by promoter methylation. 1538 30

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