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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rabbit heteroantisera anti-Meth A sarcoma (H-2d) (RAMA) and rabbit anti-RBL-5 leukemia (H-2b) (RAR-5) have been used to study the presence of normal strain antigens on the surface of different murine tumour cells. RAR-5 detected H-2-like structures on TLX9 (H-bb) lymphoma, however RAMA did not on LSTRA leukemia (H-2d) mastocytoma. Neither RAR-5 nor RAMA contained antibodies against non-H-2 and differentiation antigens.
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PMID:[Strain-specific antigens detected on murine tumour cells by means of rabbit heteroantisera (author's transl)]. 31 51

The acute promyelocytic leukaemia (APL) 15;17 translocation generates a PML/RAR alpha chimeric gene which is transcribed as a fusion PML/RAR alpha mRNA. Molecular studies on a large series of APLs revealed great heterogeneity of the PML/RAR alpha transcripts due to: (i) variable breaking of chromosome 15 within three PML breakpoint cluster regions (bcr1, bcr2 and bcr3), (ii) alternative splicings of the PML portion and (iii) alternative usage of two RAR alpha polyadenylation sites. Nucleotide sequence analysis predicted two types of proteins: multiple PML/RAR alpha and aberrant PML. The PML/RAR alpha proteins varied among bcr1, 2 and 3 APL cases and within single cases. The fusion proteins contained variable portions of the PML N terminus joined to the B-F RAR alpha domains; the only PML region retained was the putative DNA binding domain. The aberrant PML proteins lacked the C terminus, which had been replaced by from two to ten amino acid residues from the RAR alpha sequence. Multiple PML/RAR alpha isoforms and aberrant PML proteins were found to coexist in all APLs. These findings indicate that two potential oncogenic proteins are generated by the t(15;17) and suggest that the PML activation pathway is altered in APLs.
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PMID:Genomic variability and alternative splicing generate multiple PML/RAR alpha transcripts that encode aberrant PML proteins and PML/RAR alpha isoforms in acute promyelocytic leukaemia. 131 66

It has become apparent that a number of genes disrupted by chromosomal rearrangements during leukaemogenesis encode protein factors involved in transcriptional regulation (20-25) and PML may be another such gene. The replacement of the NH2-terminal transactivation domain in RAR alpha by the PML putative DNA binding and transactivation domains in the PML/RARA fusion produces a novel chimeric protein which may act to block normal myeloid differentiation through disregulation of the genes normally regulated by either or both of the normal proteins.
Leukemia 1992
PMID:A previously uncharacterized gene, PML, is fused to the retinoic acid receptor alpha gene in acute promyelocytic leukaemia. 131 62

Tremendous advances in our understanding of acute leukemia have been made through the development of new technologies and close collaboration between immunologists, molecular biologists, and clinical oncologists. These technological advances have included the development of monoclonal antibodies (MoAb) reactive with surface antigens on leukemic cells which can help confirm the lineage and diagnosis of acute leukemia. More importantly, MoAb in conjunction with morphology and cytochemical stains have led to the identification of FAB-MO and the more common recognition of FAB-M7. MoAbs have also helped define prognostic groups, e.g., T-cell leukemia, mature B-cell leukemia, and rare groups such as CD7+ AML. However, the greatest advances in our understanding of acute leukemia has occurred with the application of genetic techniques. Disregulation of genes responsible for normal growth and differentiation initiates the molecular events that lead to the transformation and proliferation of cells recognized clinically as leukemia. Non-random cytogenetic abnormalities apparently contribute to this gene disregulation and specific abnormalities are associated with clinically important subgroups. In acute lymphoblastic leukemia (ALL), the t(9;22), t(1;19), and t(4;11) appear to have a poor prognosis. In acute myeloblastic leukemia (AML), -7/7q-;-5/5q-, 11q23 abnormalities have poor outcomes while t(15;17) and in some series t(9;11), t(8;21), and inv(16) have a good response to therapy. Molecular studies of somatic cell (immunoglobulin and T-cell receptor) gene rearrangements have assisted in the diagnosis and classification of ALL. The application of the polymerase chain reaction technique to specific gene rearrangements has provided a useful approach to minimal residual disease. Specific gene activation (N-myc, evi-1) or fusion genes such as the alpha retinoic acid receptor (alpha RAR) and pml have been identified as the specific cause of some cases of leukemia. The cloning of specific chromosomal breakpoints identified in leukemia (as has been done for CML) will result in specific probes which can be used to make the diagnosis rapidly at the molecular level. Because of the tremendous number of recent developments, this paper will focus only on major developments that will soon have a clinical impact.
Leukemia 1992 Nov
PMID:Pathology and immunology of acute leukemia. 143 16

We report the isolation of a maturation-resistant acute promyelocytic leukemia (APL) cell line. This permanent cell line, derived from the same patient as the maturation inducible NB4 cell line, is the first retinoid-resistant cell line with a t(15;17) chromosomal translocation. Morphological, immunocytochemical and molecular features of the maturation responsive (NB4) and unresponsive (NB4-RAr) cells are compared. The isolation of the NB4-RAr cell line occurred through a two-step process requiring the continuous selective pressure of all-trans-retinoic acid. Cells are also resistant to 13-cis-retinoic acid. Karyotypic and Southern-blot analyses show that the two cell lines are similar with respect to the translocation. Northern-blot analyses show that the chimeric fusion transcript PML-RAR alpha and the normal allelic PML and RAR alpha transcripts are similarly expressed in both cell lines. The molecular basis for unresponsiveness to retinoic acid is not known. This resistant cell line offers a cellular model for molecular biology studies on the mechanism of induction of APL cell maturation, as well as a means to elucidate the molecular mechanisms of resistance. It also furnishes a unique tool for designing and/or screening new therapeutic drugs to avoid or relieve retinoid maturation blockage.
Leukemia 1992 Dec
PMID:A retinoid acid 'resistant' t(15;17) acute promyelocytic leukemia cell line: isolation, morphological, immunological, and molecular features. 145 73

We have previously shown that all-trans retinoic acid therapy is an alternative therapy for acute promyelocytic leukemia (AML3) via differentiation of the leukemic cells. The t(15;17) translocation is specifically found in this leukemia. We and others have shown that through this translocation the RAR alpha gene is rearranged and its expression altered in AML3 cells. The gene is truncated and fused to a novel gene (PLM). This results in a fusion protein whose transactivating properties may be implicated in the leukemogenesis of this disease. Retinoic acid cytoplasmic binding proteins (CRABP and CRBP) are not detected by PAGE chromatography in normal or malignant hematopoietic cells. During all-trans RA therapy, a) all-trans RA plasma concentrations are within in vitro differentiating concentration (med. 0.4 microgram/ml); b) increased expression of the normal remaining RAR alpha allele is rapidly observed and may explain the paradoxical induction of RA differentiation in these cells; c) CRABPII is induced in the bone marrow cells of AML3 patients and remains detectable 1 month after withdrawal of RA. AML3 in relapse after RA therapy is always less sensitive to RA in vitro and in vivo. Our data suggest that modification of the metabolisation pathways of RA may be one of parameters linked to this resistance. It appears that the efficacy of all-trans RA is the resultant of multiple parameters (RA concentration, ratio of PML/RAR alpha transcripts to normal RAR alpha, CRABP) which need to be defined to efficiently monitor all-trans RA therapy in APL.
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PMID:[Biological parameters of the efficiency of retinoic acid in acute leukemia]. 182 94

The expression of the newly described human retinoic acid receptor alpha (RAR alpha) in six nonlymphoid and six lymphoid leukemia cell lines and nine freshly obtained samples of leukemia cells from patients with acute nonlymphoid leukemia was assessed by Northern blot analysis, using a full length cDNA clone of RAR alpha as probe. RAR alpha was expressed in all 12 cell lines and in all fresh leukemia samples as two major transcripts of 2.6 and 3.5 kb in size. Levels of RAR alpha expression and transcript sizes in retinoid-sensitive cells (such as HL60 or fresh promyelocytic leukemia cells) were not different from those in other samples. Moreover, expression of RAR alpha was not significantly modulated by exposure to cis-retinoic acid (cisRA) in either cisRA-responsive or unresponsive cells. By using a 3' fragment of the RAR alpha gene as a probe, we confirmed that the transcripts visualized did not represent the homologous RAR beta gene. RAR alpha appears to be expressed in most human leukemia cells regardless of the type of biologic response to retinoic acid.
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PMID:Expression of retinoic acid receptor alpha mRNA in human leukemia cells. 254 26

Specific [3H]retinoic acid (RA)-binding sites in nuclear and cytosolic extracts prepared from human myeloblastic leukemia HL-60 cells have been detected by sucrose density gradient sedimentation and size-exclusion high-performance liquid chromatography (HPLC) analyses. This RA-binding activity migrated as a single peak with an apparent molecular weight of 50,000 and greater than 95% of the total binding activity was associated with the nuclear extract. Nuclear extracts prepared from COS-1 cells transfected with an expression vector for the nuclear RA receptors RAR alpha or RAR beta were enriched (20- to 100-fold) with a RA-binding activity that coeluted by size-exclusion HPLC with the putative RAR from HL-60 cells. The HL-60 nuclear receptor exhibited high-affinity binding of RA and its benzoic acid analogs Ch55, Ch30, Ro 13-7410, and SRI 6409-40 and low-affinity binding of retinol, Ro 8-8717, and SRI 5442-60, correlating well with the biological activity of these compounds in HL-60 cells. Saturation binding and Scatchard plot analyses of the binding of RA to the nuclear HL-60 receptor yielded an apparent dissociation constant of approximately 0.46 nM and 1400 +/- 100 receptor sites per cell. Northern blot analyses of poly(A)+ RNA with cDNA probes specific for RAR alpha and RAR beta indicated that HL-60 cells contain predominantly transcripts encoded by the RAR alpha gene. Our results suggest that the observed nuclear RA-binding activity in HL-60 cells might mediate the action of RA in these cells.
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PMID:Identification and characterization of nuclear retinoic acid-binding activity in human myeloblastic leukemia HL-60 cells. 254 90

Receptors for IgE from peritoneal mast cells (RMC) of six strains of rats were studied and compared with those of rat basophilic leukemia cells (RBL). Receptors were isolated from surface iodinated and detergent solubilized cells by means of IgE-Sepharose, IgE and anti-IgE, and a rabbit antiserum specific for the receptors of RBL cells (RAR). Like RBL cells, RMC from all rate strains were shown to be associated with two receptor molecules H and R, having apparent m.w. of about 55,000 and 45,000, respectively. THe presence of both molecules could be clearly demonstrated with RAR. When IgE-Sepharose was used, the presence of H could only be unequivocally shown if large numbers of IgE molecules were bound to the RMC.
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PMID:The presence of two kinds of receptors for IgE on rat mast cells. 741 Aug 42

Acute promyelocytic leukemia (APL) serves as a paradigm in clinical and biological leukemia research. Firstly, APL represents a model for the new therapeutic approach of differentiation therapy, taking advantage of the ability of APL cells to respond to retinoic acid treatment by terminal differentiation. Secondly, the 15;17 chromosomal translocation specific for APL leads at the molecular genetic level to a chimeric gene fusing the PML and RAR alpha genes and appears to be an instrumental, if not actually the causative event, in the neoplastic process. These unique characteristics of an otherwise rather rare disease have recently attracted intense research interest. As in other types of leukemia where continuous cell lines are powerful research tools, studies using APL-derived cell lines have contributed a large body of relevant data in efforts to unravel the pathobiology and leukemogenesis of APL. Three cell lines have been reported to be derived from patients with APL: HL-60, NB-4 and PL-21. Both HL-60 and PL-21 lack t(15;17) while NB-4 carries this cytogenetic hallmark pathognomonic for APL. Morphological and immunophenotypical examinations of the cell lines do not permit a clear assignment to any stage of myelomonocytic differentiation. Some additional data, such as expression of myeloperoxidase, monocyte-specific esterase and annexin VIII, together with the cytogenetic and molecular biological information, suggest that NB-4 is the only genuine promyelocytic leukemia cell line, whereas HL-60 may represent a discrete stage of differentiation between the late myeloblasts and the promyelocyte; PL-21 has distinct features associated with monocytic cells. These cell lines provide unique in vitro model systems for studying the cellular and molecular events involved in the proliferation and differentiation of normal and leukemic myelomonocytic cells.
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PMID:Leukemia cell lines: in vitro models for the study of acute promyelocytic leukemia. 750 Jun 43


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