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

Bone marrow (BM) cells from two transgenic mice carrying the human c-myc oncogene were separately harvested, and each sample was injected into 25 lethally irradiated mice. We observed the contribution of the myc gene to the occurrence of hemopoietic neoplasms in the BM-repopulated mice, establishing a new experimental system for analyzing oncogene expression in the hemopoietic system in vivo. The hybrid gene that was transferred into the original transgenic mice was a combination of the human c-myc gene with a regulatory unit consisting of a murine immunoglobulin-heavy chain with an SV40 early-T promoter gene (Ig/Tp-myc). Among the transgenic lines, the tested BM cells were chosen from two lines that had been low-prone in leukemia; in these lines hemopoietic neoplasms did not appear for greater than or equal 200 days after birth. Lethally irradiated controls received BM cells from litters of transgenic mice that did not carry c-myc. The lifetime incidence of hemopoietic neoplasms was 94% and 91% in the two groups of mice repopulated with myc+ BM. By contrast, only 15% of control mice with myc- BM developed hemopoietic lesions. The incidence of hemopoietic malignancies combined with nonthymic lymphomas and myeloma cases (88% and 65%) was higher in the repopulated mice than the incidence of pre-B cell lymphomas in the original transgenic lines (56%). Thirty-two of the 40 myc+ mice that were examined showed the presence of the transferred gene in either the normal hemopoietic tissue or in the hemopoietic neoplasm. Furthermore, 18 of 22 hemopoietic neoplasms studied by Northern hybridization expressed mRNA from the transgenic gene; in other four neoplasms, expression was weak or absent.
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PMID:Hemopoietic neoplasms in lethally irradiated mice repopulated with bone marrow cells carrying the human c-myc oncogene: a repopulation assay. 154 84

We have used nuclear run-on and DNase I sensitivity analyses to study the activity of the N-myc genes in cell lines that represent different stages of B-cell development. Both transformed pre-B-cell lines and a nontransformed pre-B-cell clone transcribe the N- and c-myc genes at substantial levels; in the nontransformed clone, transcription of these genes is regulated by the pre-B-cell growth factor interleukin-7. In contrast, transformed cell lines that represent the more mature stages of the B-cell pathway and mitogen-stimulated normal splenic B lymphocytes express the c-myc gene but do not express the N-myc gene at detectable levels. Down-regulation of N-myc expression in these cells occurs at the level of transcriptional initiation. Correspondingly, a set of DNase I-hypersensitive sites present in the 5' region of the N-myc promoter of pre-B-cell lines are absent in B-cell lines. To further elucidate this process, we have constructed fusion cell lines between an N-myc-expressing pre-B-cell line and a nonexpressing myeloma line; the hybrid cell lines transcriptionally down-regulate the pre-B copies of the N-myc gene. Lack of N-myc expression in a number of nonlymphoid cell lines also resulted from lack of N-myc transcription. Together, our findings demonstrate that the down-regulation of N-myc expression in the later stages of B-cell development is mediated primarily at the level of transcriptional initiation. They further show that dominant, trans-acting factors present in more mature B-lineage cell lines act to down-regulate the transcription of N-myc.
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PMID:Transcriptional down-regulation of N-myc expression during B-cell development. 154 13

Deregulated c-myc expression, as a consequence of translocation of the c-myc gene to one of the immunoglobulin loci, appears to play an important role in the pathogenesis of several B-cell tumors, including Burkitt's lymphoma, mouse plasmacytoma and rat immunocytoma. This study investigated the expression of c-myc and 2 other members of the myc gene family, L- and N-myc, at the mRNA and protein level, and analyzed for possible rearrangements of these genes in the human counterpart to the mouse plasmacytoma--multiple myeloma (MM). Nine well-characterized MM cell lines were examined by using Northern- and Southern-blot analysis and immunoprecipitation. The c-myc gene was found to be highly expressed in most MM cell lines. The level of expression was comparable to that observed in the COLO 320 and HL-60 cell lines, carrying amplified c-myc genes, and to that of B-cell lines with a higher proliferative activity than the MM cell lines. In the U-266 MM cell line, L-myc, but no c-myc mRNA or protein, was found. The L-myc gene was expressed in both early- and late-passage U-266 cells, suggesting that the L-myc expression was not the result of the in vitro cultivation. N-myc was not expressed in any of the MM cell lines. No rearrangements of c-myc or L-myc genes were found. We thus conclude that (a) in contrast to the corresponding mouse and rat B-cell tumors, c-myc is not frequently rearranged in MM; (b) c-myc is highly expressed in most MM lines; and (c) L-myc but not c-myc is expressed in the U-266 MM cell line.
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PMID:Expression of myc-family genes in established human multiple myeloma cell lines: L-myc but not c-myc gene expression in the U-266 myeloma cell line. 156 31

The natural history of multiple myeloma and related human plasma cell tumors is compared to the process of plasmacytomagenesis in mice. Intriguing new findings are beginning to give a more complete picture of the evolution of these tumors. Mouse plasmacytomas consistently develop chromosomal translocations that dysregulate c-myc, but consistent oncogenic mutations have not yet been defined in multiple myeloma.
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PMID:Perspectives on the origins of multiple myeloma and plasmacytomas in mice. 158 69

A 58-year-old female was admitted to our hospital because of anemia in March 1987. Monoclonal protein (IgA, kappa) was detected and a diagnosis of multiple myeloma was made. Partial remission was obtained after VAD therapy with alpha-interferon. In December 1989, she was readmitted because of a pathological fracture of the left humerus. A white blood cell count was 4400/microliters with 30% myeloma cells and the urine protein (Bence Jones protein) was 26 g/day. Systemic chemotherapy was not effective. She developed pleural and pericardial effusions, bone mass, disturbance of consciousness and died of respiratory failure only 3 months after readmission. The pleural and pericardial fluids contained many myeloma cells. c-myc gene rearrangement was detected in myeloma cells obtained from the pleural fluid using c-myc exon1 and exon2 probes. The levels of interleukin-6 (IL-6) measured by ELISA was 107.4 pg/ml in serum, 56.2 pg/ml in pleural fluid and 780.0 pg/ml in pericardial fluid. Because of the lack of any overt infectious focus, the level of IL-6 appears to have been related to aggressive proliferation of myeloma cells. It was of interest that C-reactive protein, induced by IL-6, was a good marker reflecting disease activity.
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PMID:[A high serum level of interleukin-6 in a patient with aggressive multiple myeloma]. 175 53

We have studied the tumorigenic potential of a series of independent intraspecies hybrid clones derived from fusion of murine myeloma (BALB/c) and normal fibroblasts (C3H). All of these hybrids grew as adherent cells and thus resembled the fibroblast phenotype. As judged by chromosome enumeration, these hybrids appear to retain the full complement of their parental cells. Three out of 4 hybrids tested were able to form colonies in soft agar and to grow as tumors in either nude or (BALB/c x C3H) F1 mice, albeit at a reduced rate. The 4th hybrid did not grow in agar, was non-tumorigenic and may have had a 2:1 fibroblast to myeloma genomic equivalence ratio. In contrast to the parental myeloma cells, all the hybrids exhibited restricted growth rates in serum-free medium. As in our previous sets of hybrids formed between myeloma and L-cells, expression of the Ig genes was inhibited in the new hybrids and the derived tumors. The constitutive expression of the translocated myc gene in the myeloma parental cells was decreased in the hybrids and in all their derived tumors. In contrast, all of the hybrid cell lines and the tumors express high levels of the intracisternal A particle mRNAs. Our results show that the tumorigenic phenotype of myeloma cells is either fully or partially suppressed in myeloma x fibroblast hybrids and that this may be due to the fact that expression of the translocated c-myc is suppressed. We suggest that, in addition to the translocated myc gene, myeloma cells contain other activated oncogene(s), and that the latter are responsible for the residual tumorigenic potential of the myeloma x fibroblast hybrids.
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PMID:Suppression of the translocated myc gene and expression of intracisternal A-particle genes in tumorigenic and non-tumorigenic hybrids between murine myeloma and normal fibroblasts. 190 5

Oncogene analyses of four human myeloma cell lines provided no indication of gene amplification or rearrangement using DNA probes for the met, raf, abl, mos, erb B, Her-2-neu, fos, myb-7, fms, L-myc, sis, and myb-1 genes. However, a consistent elevation of up to 23-fold in the level of c-myc mRNA was observed in all of the cell lines studied. No restriction fragment length polymorphism (in exons one, two, or three) or c-myc gene amplification has as yet been demonstrated to account for the c-myc mRNA elevation. The c-myc mRNA has a half-life of 25 min which is comparable to that observed in other systems. The elevation in c-myc mRNA is further evidence for the role of the c-myc proto-oncogene in the pathogenesis of myeloma.
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PMID:Elevated c-myc messenger RNA in multiple myeloma cell lines. 198 Feb 37

Alteration and abnormal expression of the c-myc oncogene were investigated in human multiple myeloma. Human myeloma cells were highly purified (more than 95%) from bone marrow aspirates in 14 cases of advanced multiple myelomas and one case of plasma cell leukaemia. Southern blotting revealed that a rearranged configuration of c-myc gene was found in only one case of them, but this was a novel truncation of the gene in its coding exon II; a rearranged 3.4 kb band was detected by digestion with Xba I using c-myc exon II probe, but no rearranged band was found using exon III probe. In this case, the truncated c-myc allele was not transcribed; normal sized (2.4 kb) c-myc mRNA was markedly expressed, but no aberrant mRNA was detected. On the other hand, by Northern blotting, the nine cases, including the case with the rearranged c-myc gene, showed increased expression of normal sized (2.4 kb) c-myc mRNA. Elevated c-myc mRNA expressions were well related to the in vitro proliferation (3H-TdR uptake), but not to IL-6 response. Interestingly, extremely high expressions of c-myc mRNA were detected in two cases of aggressive myelomas, including the case with the rearranged c-myc gene, and in one of plasma cell leukaemia. These two cases of aggressive myelomas were the ones who showed the markedly high 3H-TdR uptakes, and had the common clinical features with the formation of an extramedullary mass and very short survival. These results suggest that the activation of c-myc gene could induce high proliferative activities and the subsequent aggressive transformation of myeloma cells.
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PMID:Increased expression of the c-myc gene may be related to the aggressive transformation of human myeloma cells. 202 78

The c-myc gene plays a pivotal role in mediating the competence state for cell cycle transversion. This biologic role is in contradiction to reports of elevated expression of the gene in multiple myeloma, a tumor with restricted self-renewal capacity. To more clearly define the role of this gene in plasma cells of myeloma patients, c-myc messenger RNA (mRNA) and/or oncoprotein expression were semiquantitatively analyzed on the single cell level in 19 cases of multiple myeloma, among them 1 biclonal case and 1 case with coexistent chronic lymphocytic leukemia (CLL). Performing anti-sense/mRNA in situ hybridization, mature c-myc gene transcripts were detected in 92% (12 of 13) of cases and could definitely be attributed to the plasma cells by our study. The number of Ki 67-positive plasma cells actively passing the cell cycle was less than 1% and independent of c-myc gene expression. However, because the presence of the 152-c-MYC epitope was correlated to extent of marrow plasmacytosis (r = .64; P = .043) and content of plasmablasts (P = .09), the c-myc gene might serve a function different from proliferative activity, but also associated with tumor cell mass. In CLL cells (21 of 22 cases) and their benign counterparts, ie, bone marrow and peripheral blood lymphocytes, the anti-sense/c-myc mRNA hybridization signals remained below the threshold considered as cutpoint between negative and positive. The low amounts of c-myc transcripts were correlated to neither stage of disease (P = .52) nor lymphocyte counts (P = .24). Because the numbers of peripheral blood lymphoma cells were independent of tumor mass and of c-myc gene transcripts expressed, peripheral blood lymphocytosis might more likely reflect homing processes than proliferative activity in CLL.
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PMID:Expression of the c-myc proto-oncogene in multiple myeloma and chronic lymphocytic leukemia: an in situ analysis. 207 52

Centrocytic lymphoma is a B-cell non-Hodgkin's lymphoma (NHL) composed of lymphocytes resembling cleaved follicular center cells (centrocytes). Previous studies have suggested an association between t(11;14) chromosomal translocations and bcl-1 rearrangement in centrocytic and related intermediate lymphocytic lymphomas. To further characterize the association between bcl-1 and centrocytic lymphoma, Southern blot analysis was performed on samples from 23 patients using four separate bcl-1 breakpoint probes spanning 63 kb of the chromosome 11 bcl-1 locus. Rearrangements were identified in six patients with the major translocation cluster (MTC) probe and in another six with probe p94PS, located about 24 kb 5' of MTC. Eleven of these 12 cases showed comigration of rearranged bcl-1 and Ig heavy chain-joining genes, consistent with the t(11;14) chromosomal translocation. No rearrangements were observed with the bcl-1 locus probes p210 or p11EH located 5' of p94PS, nor with bcl-2 or c-myc oncogene probes. No bcl-1 rearrangements were identified in B-cell follicular NHL (15), small noncleaved cell (Burkitt's and non-Burkitt's) NHL (8), T-cell NHL (4), multiple myeloma (14), and pre-B-cell acute lymphoblastic leukemia (9). One of 23 B-cell NHL of large cell type and one of 19 chronic lymphocytic leukemias or small lymphocytic NHL had MTC rearrangement. Thus, bcl-1 rearrangement occurred at MTC or p94PS in 12 of 23 centrocytic lymphomas (52%), confirming a nonrandom association and suggesting a pathogenetic role for the bcl-1 locus in this immunohistologic subtype of NHL.
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PMID:Rearrangement of the chromosome 11 bcl-1 locus in centrocytic lymphoma: analysis with multiple breakpoint probes. 207 85


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