Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have performed gene rearrangement studies on the leukemic blasts of a patient with acute pre-B-cell leukemia. The patient had a 5 year history of follicular lymphoma, which developed into acute pre-B-cell leukemia. The leukemic blasts revealed a karyotype with two translocations, t(8; 14) and t(14; 18), characteristic for Burkitt's lymphoma and follicular lymphoma. The cells are TdT positive, do not possess surface immunoglobulin, and they show immunoglobulin gene rearrangement. The mu heavy chain and kappa light chain constant (C mu and C kappa) loci are deleted, while the gamma and lambda light chain constant (C gamma and C lambda) region genes are rearranged. Both alleles of the heavy chain joining segment (JH) are rearranged on chromosome 14q+, one of them with the bcl-2 oncogene from chromosome 18. The breakpoint of the t(14; 18) translocation occurs in the major breakpoint cluster region in the 3' untranslated region of bcl-2. On chromosome 8 a c-myc rearrangement was mapped immediately 5' to the c-myc first exon in a region involved in sporadic Burkitt lymphoma. The data are consistent with our previous hypothesis on the evolution of B-cell malignancies: a rare pre-B cell develops a t(14; 18) translocation during immunoglobulin VDJ joining that results in an expansion of a follicular lymphoma clone carrying an activated bcl-2 gene. Within the clone of pre-B cells a second translocation, t(8; 14), occurs during heavy chain isotype switching that results in the deregulation of the c-myc involved in the translocation.
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PMID:Pre-B-cell leukemia with a t(8; 14) and a t(14; 18) translocation is preceded by follicular lymphoma. 313 17

We have determined that the bcl-2 (B-cell leukemia/lymphoma 2) gene is transcribed into three overlapping mRNAs, and we have cloned bcl-2 cDNA sequences. Sequence analysis of the bcl-2 cDNA clones and comparison of their sequences to their genomic counterparts indicate that the bcl-2 gene contains at least two exons. The three bcl-2 transcripts, which are 8.5, 5.5, and 3.5 kilobases (kb) long, overlap within the first exon, but only the 8.5-kb and 5.5-kb transcripts contain sequences of the second exon. The 8.5-kb and 5.5-kb transcripts seem to use different polyadenylylation sites. Sequence analysis of the cDNA clones corresponding to the 5.5-kb and 3.5-kb mRNAs indicates that the two bcl-2 transcripts carry two overlapping open reading frames, one of which is 717 nucleotides long and codes for a protein (bcl-2 alpha) of 239 amino acids and a molecular mass of 26 kDa, while the other codes for a protein of 205 amino acids (bcl-2 beta, molecular mass 22 kDa) that is identical to bcl-2 alpha except at the carboxyl terminus. The bcl-2 protein products in follicular lymphomas with or without bcl-2 rearrangements are identical to the normal bcl-2 products.
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PMID:Analysis of the structure, transcripts, and protein products of bcl-2, the gene involved in human follicular lymphoma. 352 87

One of the most common karyotypic abnormalities is the t(14;18) translocation, which is found in many lymphomas that have a characteristic follicular morphology. Recent molecular studies have shown that this chromosomal translocation results in the juxtaposition of the candidate proto-oncogene bcl-2 (B-cell leukemia-lymphoma) on chromosome 18 with the immunoglobulin heavy-chain locus on chromosome 14. However, because performing accurate cytogenetic studies in solid hematolymphoid neoplasms is difficult, knowledge of the prevalence of the t(14;18) translocation and, by association, the extent of bcl-2 involvement in human lymphomas is limited. We used a number of chromosome-18 DNA probes to analyze various subtypes of Hodgkin's and non-Hodgkin's lymphomas and test for structural abnormalities near or within the bcl-2 gene. Molecular features of the t(14;18) translocation were found in virtually all follicular neoplasms and about 28 percent of diffuse large-cell lymphomas. No changes in bcl-2 were found in several other subtypes of Hodgkin's and non-Hodgkin's lymphomas, including those previously suggested to originate from follicular-center cells and those about which cytogenetic data have been difficult to obtain. Our findings suggest a close pathogenetic relation between bcl-2 and a large group of non-Hodgkin's lymphomas, both with and without a follicular morphology. The methods employed in this study may be useful in improving the accuracy of diagnosis and subclassification of malignant lymphomas.
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PMID:Molecular analysis of the t(14;18) chromosomal translocation in malignant lymphomas. 365 90

From an acute B-cell leukemia cell line, a DNA probe was obtained that was specific for chromosome 18 and flanked the heavy chain joining region of the immunoglobulin heavy chain locus on chromosome 14. This probe detected rearrangement of the homologous DNA segment in the leukemic cells and in follicular lymphoma cells with the t(14:18) chromosome translocation but not in other neoplastic or normal B or T cells. The probe appears to identify bcl-2, a gene locus on chromosome 18 (band q21) that is unrelated to known oncogenes and may be important in the pathogenesis of B-cell neoplasms with this translocation.
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PMID:Cloning of the chromosome breakpoint of neoplastic B cells with the t(14;18) chromosome translocation. 609 63

The expression of the proto-oncogene bcl-2 was examined in a panel of 75 continuous human leukemia-lymphoma cell lines originated from different hematopoietic cell types. The presence of the bcl-2 protein, as evidenced by Western blotting, and its mRNA, as determined by Northern blotting, were not restricted to cells with the chromosomal translocation t(14;18)(q32;q21), but were also detected in a large number of cell lines without t(14;18). The amount of the bcl-2 protein and mRNA in the cell lines with t(14;18) was in the same order of magnitude as in other bcl-2 expressing cell lines of the same lineage, but without the translocation. Bcl-2 was found in all types of hematopoietic cell lines which were assigned to the following lineages based on their phenotypical characteristics: pre-B, B, plasma, T, myeloid, monocytic, erythroid-megakaryocytic and Hodgkin's lymphoma derived cell lines. The levels of accumulated mRNA and protein corresponded fairly well in most of the cell lines examined. Our results suggest the notion that bcl-2 expression is widely present in hematopoietic cell lines without restriction to single lineages and, in fact, clearly independent of the chromosomal aberration t(14;18). It is conceivable that bcl-2 expression is a common feature in established hematopoietic cell lines and may contribute to their unlimited growth in vitro.
Leukemia 1995 Nov
PMID:Expression of bcl-2 mRNA and protein in leukemia-lymphoma cell lines. 747 72

By suppressing apoptosis, hemopoietic growth factors (HGFs) promote the survival of CD34+, HLA-DR+ marrow cells that are enriched for hemopoietic progenitor cells (HPC). In the present studies, we have examined the effects of pIXY321, a genetically engineered fusion protein of GM-CSF and IL-3 (GM-CSF/IL-3), on high-dose Ara-C (HIDAC) and taxol-induced apoptosis and survival of a multilineage HPC, the CFU-GEMM. Exposure to 1.0 mumol/l taxol for 24 h or HIDAC > or = 10 mumol/l for 4 h induced internucleosomal DNA fragmentation and the morphologic features of apoptosis in CD34+, HLA-DR+ cells. These treatments were associated with > or = 50% inhibition of the assayable CFU-GEMM colony numbers. Incubation in serum-free medium (SFM) alone for 24 h also induced apoptosis of CD34+, HLA-DR+ cells, which was associated with reduced intracellular levels of the bcl-2 gene product p26BCL-2. Co-treatment with pIXY321 (10 ng/ml) inhibited apoptosis of CD34+, HLA-DR+ cells incubated in SFM, without significantly increasing the intracellular p26BCL-2 levels. Furthermore, co-treatment with pIXY321 significantly reduced taxol- and Ara-C-induced apoptosis and promoted the survival of CFU-GEMM (P < 0.05). Taxol and Ara-C mediated apoptosis of CD34+, HLA-DR+ cells, and its inhibition by pIXY321, was not accompanied by any significant alteration in the intracellular p26BCL-2 levels. By demonstrating that co-treatment with pIXY321 confers significant protection against apoptosis of CD34+, HLA-DR+ cells as well as promotes survival of normal HPC exposed to clinically relevant schedules and concentrations of taxol of Ara-C, these results support the design of chemotherapy regimens incorporating pIXY321 plus taxol and/or high-dose Ara-C for solid tumors and/or acute leukemias. It is hoped that the use of such a cytokine might maintain normal HPC numbers following chemotherapy, therefore avoiding prolonged suppression.
Leukemia 1995 Nov
PMID:pIXY321 protects against Ara-C or taxol-induced apoptosis and loss of clonogenic survival of normal human bone marrow progenitor cells. 747 74

Apoptin, a small protein encoded by chicken anemia virus (CAV) was expressed in various human hematologic malignant cell lines derived from leukemias and lymphoma. Three of these cell lines contain bcl-2 or BCR-ABL proteins, known to block apoptosis induced by chemotherapeutic compounds. By immunofluorescence and propidium-iodide staining apoptin was shown to induce apoptosis in all analysed cell lines. Early after expression, apoptin exhibited a fine-granular distribution in the still intact nucleus. Later, apoptin became aggregated and the nucleus segmented. The data with truncated apoptin indicate that for optimal induction of apoptosis apoptin has to be located in the nucleus.
Leukemia 1995 Oct
PMID:Apoptin, a protein encoded by chicken anemia virus, induces cell death in various human hematologic malignant cells in vitro. 747 2

E mu-bcl-2 transgenic mice bearing the bcl-2 proto-oncogene linked to the immunoglobulin enhancer (E mu) sporadically develop B or T cell lymphomas after a long latent period. To identify genes that play important roles in development of lymphoid malignancies, proviral insertional mutagenesis with Moloney murine leukemia virus (MMuLV) was carried out in two lines of transgenic mice expressing the bcl-2 gene primarily in B or T cells. MMuLV infection of non-transgenic mice induced primarily mature T cell lymphomas. By contrast, infection of newborn E mu-blc-2 mice with the virus accelerated lymphomagenesis, and nearly all of the mice eventually succumbed to clonal pre-B, B, or mainly immature T cell lymphoma, indicating the active contribution of the bcl-2 gene in lymphomagenesis. Southern blot analysis of tumor DNA from MMuLV-infected transgenic mice revealed a proviral insertion at the c-myc gene in 26% (9/35) of tumors, at the pim-1 gene in 6% (2/35) and at the pim-2 (recently renamed tic-1) gene in 23% (8/35). Some tumors carried two activated oncogenes. No insertion was detected at the bmi-1 gene. These data suggest the usefulness of this transgenic system for analysis of lymphomagenesis involving the activated bcl-2 gene.
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PMID:Moloney murine leukemia virus infection accelerates lymphomagenesis in E mu-bcl-2 transgenic mice. 747

We studied a variant CD5- B cell chronic lymphocytic leukemia (CLL) cell population that produces pathologic IgM kappa rheumatoid factor autoantibodies. In contrast to common CD5+ B cell CLL, this variant leukemia cell population displays intraclonal diversity in its expressed Ig V genes, similar to that noted for follicular B cell non-Hodgkin's lymphomas. Also, in contrast to common B cell CLL, these leukemia cells rapidly undergo cell death hours after being placed in tissue culture. We find that addition of Ag (aggregated human IgG) enhances significantly the survival of these cells in vitro. Leukemia cell survival also could be enhanced by exogenous IFN-gamma or anti-CD40 presented on Fc gamma RII (CDw32)-expressing L cells, but not by exogenous IL-4, IL-6, or monomeric human IgG. We find that Ag acts directly on the leukemia B cells to inhibit apoptosis. This effect could be mimicked by cross-linking the leukemia cells' surface IgM receptors with immobilized murine mAb specific for human Ig mu-chains, but not by immobilized mAb of irrelevant specificity. In contrast to most follicular NHL, this leukemia B cell population does not have evidence of bcl-2 gene rearrangement. Also, in contrast to non-Hodgkin's lymphomas and most B cell CLL, these cells do not express detectable amounts of bcl-2. Finally, although capable of inhibiting apoptosis, surface Ig receptor cross-linking does not induce expression of bcl-2 in these variant leukemia cells. We hypothesize that the lack of bcl-2 expression may render these leukemia cells particularly dependent upon the survival signal(s) derived from surface Ig receptor cross-linking. This state may represent an early stage in leukemia/lymphomagenesis, possibly accounting for the intraclonal diversity observed in the Ig V genes expressed by certain CD5- B cell leukemias and lymphomas.
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PMID:Autoantigen inhibits apoptosis of a human B cell leukemia that produces pathogenic rheumatoid factor. 750 24

It has been reported that human promyelocytic leukemic HL-60 cells which undergo differentiation fail to respond by apoptosis when treated with antitumor drugs, predominantly DNA topoisomerase inhibitors. Because S phase cells are selectively sensitive to these drugs, and during differentiation there is a reduction in the proportion of cells in S phase, the reported decrease in the number of apoptotic cells could simply be a reflection of the paucity of sensitive cells in these cultures. Using cytometric methods which allow apoptosis to be related to cell cycle position, we have compared the apoptotic response of HL-60 cells growing exponentially and induced to myeloid differentiation by dimethyl sulfoxide (DMSO). The cells were treated with: (i) the DNA topoisomerase I inhibitor camptothecin (CAM), which selectively triggers apoptosis or S phase cells; (ii) the nucleoside antimetabolite 5-azacytidine (AZC) and hyperthermia, both of which preferentially affects G1 cells; and (iii) gamma radiation, which causes apoptosis predominantly of G2 + M cells. The cells exposed to 1.4% DMSO for 24 or 48 h were significantly more resistant to response by apoptosis, regardless of the nature of the agent and regardless of their position in the cell cycle. Thus, induction of differentiation lowers the cell's ability to respond to a variety of damaging agents by apoptosis and this effect is not correlated with cell cycle position. In addition, the difference in response was unrelated to expression of the apoptosis-modulating protein bcl-2, which appeared unchanged following 48 h exposure to DMSO. On the other hand, when the cells were pretreated with low concentrations of CAM or AZC, washed free of drug, and then treated with DMSO, the proportion of cells undergoing apoptosis was markedly increased, relative to drug-treated cells returned to DMSO-free medium. The present data may indicate that while the drug-induced damage screening mechanisms, which are linked to triggering apoptosis, may be more proficient in proliferating cells, the effectors of apoptosis are more expressed in cells undergoing differentiation. The data also suggest that the efficiency of chemotherapeutic agents or radiation may be reduced if a differentiating agent is used in combination therapy and is administered first. An enhancement of apoptosis, however, may be expected if the differentiating drug is administered in the reverse sequence.
Leukemia 1994 Feb
PMID:Altered susceptibility of differentiating HL-60 cells to apoptosis induced by antitumor drugs. 750 35


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