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)

It has been known for several years that DNA replication and histone synthesis occur concomitantly in cultured mammalian cells. Normally all five classes of histones are synthesized coordinately. However, mouse myeloma cells, synchronized by starvation for isoleucine, synthesize increased amounts of histone H1 relative to the four nucleosomal core histones. This unscheduled synthesis of histone H1 is reduced within 1 h after refeeding isoleucine, and is not a normal component of G1. The synthesis of H1 increases coordinately again with other histones during the S phase. The DNA synthesis inhibitors, cytosine arabinoside and hydroxyurea, block all histone synthesis in S-phase cells. The levels of histone H1 mRNA, relative to the other histone mRNAs, is increased in isoleucine-starved cells and decreases rapidly after refeeding isoleucine. The increased incorporation of histone H1 is at least partially due to the low isoleucine content of histone H1. Starvation of cells for lysine resulted in a decrease in H1 synthesis relative to core histones. Again the ratio was altered on refeeding the amino acid. 3T3 cells starved for serum also incorporated only H1 histones into chromatin. The ratio of different H1 proteins also changed. The synthesis of the H1(0) protein was predominant in G0 cells, and reduced in S-phase cells. These data indicate the metabolism of H1 is independent of the other histones when cell growth is arrested.
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PMID:Uncoordinate synthesis of histone H1 in cells arrested in the G1 phase. 715 89

Of 5 multiple myeloma patients with hyperammonemia, autopsy was performed in 4 patients, while amino acid metabolism was examined in 3 patients. As a result they were classified into the following 3 types; A, liver dysfunction and severe liver infiltration of myeloma cells. B, severe liver infiltration without liver dysfunction. C, Neither liver dysfunction nor severe liver infiltration. In one type A patient, isoleucine decreased. In two patients without liver dysfunction (one type C patient and another patient in whom autopsy was not performed) valine, leucine and isoleucine decreased, and tyrosine decreased slightly. The Fischer ratio decreased in these 2 patients, while it decreased slightly in a type A patient. Clinically, in 4 patients hyperammonemia was observed during periods of poor general condition and when refractory to chemotherapy. In an aggressive type case, consciousness disturbance was developed rapidly and multiple myeloma was diagnosed. In all patients, consciousness disturbance was noted. Hyperammonemia might have been caused by hepatic failure or systemic-portal shunt in patients with liver infiltration. In those without liver infiltration, it was suggested that hyperammonemia was caused by myeloma related humoral factors that influence amino acid metabolism.
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PMID:[Clinicopathological study of multiple myeloma associated with hyperammonemia]. 949 50

The polyneuropathy, organomegaly, endocrinopathy, M protein, skin changes (POEMS) syndrome is a rare multisystemic disorder associated with osteosclerotic myeloma and multicentric Castleman's disease (MCD). Human herpesvirus type 8 (HHV-8) DNA sequences have been detected in lymph nodes of about 40% of human immunodeficiency virus (HIV)-negative patients with MCD, and in bone marrow stromal cells of patients with multiple myeloma. Considering these data, we investigated the presence of HHV-8 in 18 patients with POEMS syndrome (9 with MCD), by nested polymerase chain reaction (N-PCR) to detect DNA sequenses in various cells and tissues obtained by biopsy or at autopsy (13 patients, of whom 7 had MCD), and by an immunofluorescence assay to detect anti-HHV-8 IgG antibodies in blood (18 patients, of whom 9 had MCD). Detection of HHV-8 DNA was performed using three different N-PCR, targeting nonoverlapping regions in open reading frame (ORF) 25 and ORF26. Seven of 13 (54%) POEMS patients had HHV-8 DNA sequences in their tissues, as assessed by all three N-PCR, and 9 of 18 (50%) had circulating anti-HHV-8 antibodies. HHV-8 was mainly detected in the subset of POEMS patients with MCD (6 of 7 [85%] for DNA sequences; 7 of 9 [78%] for antibodies). The percentage of positive N-PCR was higher in lymph nodes than in bone marrow samples (P <.02). Sequencing of amplicons showed a homogeneous restricted variability in the ORF26 region, characteristic of the minority subgroup B defined by Zong, and responsible for isoleucine and glycine substitutions at amino acid positions 134 and 167. These findings strongly suggest an association of HHV-8 infection with POEMS syndrome-associated MCD.
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PMID:Human herpesvirus 8 infection in patients with POEMS syndrome-associated multicentric Castleman's disease. 1033 70

The lessons learned from the remarkably successful use of the first-generation tyrosine kinase inhibitor (TKI) imatinib in patients with chronic myeloid leukemia resulted in a major paradigm shift in the treatment of many human cancers, and now further lessons are being learned from our enhanced understanding of the molecular mechanisms of resistance to imatinib and second-generation TKIs, particularly dasatinib and nilotinib. Although diverse mechanisms seem to be involved, the principal cause appears to be the emergence of point mutations in the Abl kinase domain that affect drug affinity and some of which impair the efficacy with which the drugs bind. Currently, > 50 different mutations have been identified, and the extent to which they confer resistance varies considerably. One of the more common mutations results from the substitution of isoleucine for threonine at Abl amino acid position 351, known as the T315I mutation. It appears that the precise position of the substitution within the kinase domain dictates the degree of resistance to TKIs, and patients with the T315I mutation develop almost complete resistance to imatinib, dasatinib, and nilotinib. Herein, we discuss the emerging strategies for circumventing resistance associated with the Bcr-Abl T315I mutation.
Clin Lymphoma Myeloma 2007 Mar
PMID:Emerging strategies for the treatment of mutant Bcr-Abl T315I myeloid leukemia. 1738 17

A 76-year-old Afro-Caribbean man presenting with heart failure was diagnosed with isolated cardiac amyloid. He had evidence of myeloma on bone marrow biopsy suggesting AL amyloid, the commonest type of systemic amyloidosis, as the underlying cause. He had no other myeloma-related organ damage. However, endocardial biopsy revealed amyloid fibrils composed of transthyretin and genetic typing established heterozygozity for the valine to isoleucine mutation at position 122 (Val122Ile). The diagnosis was therefore hereditary systemic amyloidosis as a result of a genetic transthyretin variant (ATTR) causing cardiac amyloidosis and coexistent asymptomatic myeloma. This requires symptomatic treatment of heart failure only. This article discusses a rare cause of heart failure and uses this case to illustrate that histological confirmation of the amyloid-causing protein is essential. Mistaken assumption of AL amyloid could have resulted in inappropriate cytotoxic therapy targeting the plasma cell clone.
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PMID:Coexistent asymptomatic myeloma and hereditary cardiac amyloidosis: an unusual case of heart failure. 2208 4

The immunomodulatory drugs (IMiDs) thalidomide, lenalidomide, and pomalidomide are approved drugs for the treatment of multiple myeloma. IMiDs induce cereblon (CRBN) E3 ubiquitin ligase-mediated ubiquitination and degradation of Ikaros transcription factors Ikaros (IKZF1) and Aiolos (IKZF3), which are essential for multiple myeloma. However, because of a single amino acid substitution of valine to isoleucine in mouse CRBN at position 391, mice are not susceptible to IMiD-induced degradation of neosubstrates. Here, we report that expression of human CRBN or the Crbn^I391V mutant enables IMiD-induced degradation of IKZF1 and IKZF3 in murine MOPC.315.BM.Luc.eGFP and 5T33MM multiple myeloma cells. Accordingly, lenalidomide and pomalidomide decreased cell viability in a dose-dependent fashion in murine multiple myeloma cells expressing Crbn^I391V in vitro. The sensitivity of murine cells expressing Crbn^I391V to IMiDs highly correlated with their dependence on IKZF1. After transplantation, MOPC.315.BM.Luc.eGFP cells expressing murine Crbn^I391V induced multiple myeloma in mice, and treatment with lenalidomide and pomalidomide significantly delayed tumor growth. This straightforward model provides a proof-of-concept for studying the effects of IMiDs in multiple myeloma in mice, which allows for in vivo testing of IMiDs and other CRBN E3 ligase modulators.
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PMID:Generation of a lenalidomide-sensitive syngeneic murine in vivo multiple myeloma model by expression of Crbn^I391V. 3318 26

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