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)

The very rapid development of techniques based on use of the polymerase chain reaction (PCR) for characterizing molecular lesions in leukaemia and lymphoma mow offers the opportunity for monitoring residual disease at a sensitivity of one malignant cell in 10(5) or 10(6) normal cells. Maximal specificity is achieved when the DNA sequences amplified are truly leukaemia-specific (i.e. BCR/ABL in CML, PML/RAR-alfa in APL, AML1/ETO in t(8; 21) AML and CBFB/MYH1 in inv(16) AML). A good level of sensitivity may also be achieved by using immunoglobin heavy chain (IGH) and T-cell receptor (TCR) gene rearrangements if a clonospecific probe can be generated. For clinical purposes the crucial issues are the following: can PCR techniques be used for confirmation of diagnosis and evaluation of extent of disease? Can PCR data obtained be developed to quantitate the PCR product and thereby increase its predictive value? These and other issues are still a matter of debate and several studies are presently in progress to address these points.
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PMID:Minimal residual disease detection in human leukemias: biologic and clinical significance. 765 31

In the t(15;17) translocation of acute promyelocytic leukemia (APL) at least three regions of the PML gene are involved in the reciprocal translocation between the PML and the RAR-alpha loci. The chimeric PML/RAR-alpha fusion transcripts can be demonstrated in all cases of APL, by a specific reverse-transcription PCR (RT-PCR). Previous studies found a correlation between expression of CD2 and involvement of the PML bcr3. In this study, we assessed this association in 43 children and adults with APL. A blind morphologic review of all smears was performed by four experienced hemopathologists who agreed the diagnosis of M3 vs M3v APL. CD2 expression on APL was detected by using different monoclonal antibodies (MoAbs) directed against specific CD2 epitopes by flow cytometry and in selected cases by Northern blot by the use of a specific CD2 cDNA probe. Nineteen of 43 cases displayed the typical microgranular features consistent with the diagnosis of M3v. Of these, 12 had the bcr3 breakpoint on chromosome 15, while seven had the bcr1 type. In 16 of the 19 patients, leukemic cells expressed both CD2 protein and the corresponding mRNA. Similarly, in the negative cases, Northern blot analysis failed to demonstrate the presence of specific mRNA. The remaining 24 patients, with the classic morphologic features of M3, were CD3 negative. These results point out that CD2 expression correlates with the FAB M3v and not with the PML breakpoints. During the course of all-trans retinoic treatment a down-modulation of CD2 expression was observed in three M3v cases. Overall, our findings might suggest a role of CD2 epitopes in the regulation of adhesion properties of APL blast cells.
Leukemia 1995 Sep
PMID:CD2 expression in acute promyelocytic leukemia is associated with microgranular morphology (FAB M3v) but not with any PML gene breakpoint. 765 12

All-trans retinoic acid (ATRA) has been used as a potent differentiation drug for acute promyelocytic leukemia (APL). Although the mechanism of its effectiveness upon APL remains unclear, the PML-retinoic acid receptor alpha (RARA) chimeric protein produced by t(15;17) is assumed to underlie the sensitivity of APL cells to ATRA. There are two major isoforms of PML-RARA transcripts; short (S) and long (L), according to the breakpoints in the PML gene. We therefore compared the clinical variables, the response to ATRA and the prognosis between 28 patients with type S and 68 patients with type L. Patients were treated in multi-institutional trials with ATRA, and chemotherapy was combined when peripheral blasts and leukocyte counts increased during the therapy. The clinical features at diagnosis were similar between the two molecular subtypes, and there was no significant difference in remission induction rates; 86% for the type S group and 90% for the type L group. There was no statistical difference in overall survival and CR duration as well as disease-free survival (DFS). In newly diagnosed patients, predicted 2-year DFS was 66% for the type S group and 67% for the type L group. In refractory or relapsed patients, it was 19 and 23%, respectively. These data indicated that isoforms of PML-RARA fused transcripts affect neither the clinical features of APL nor the prognosis after treatment with ATRA.
Leukemia 1995 Sep
PMID:Isoforms of PML-retinoic acid receptor alpha fused transcripts affect neither clinical features of acute promyelocytic leukemia nor prognosis after treatment with all-trans retinoic acid. The Leukemia Study Group of the Ministry of Health and Welfare (Kohseisho). 765 15

Retinoic acid (RA) is a vitamin A derivative with striking effects on development and cell differentiation. The identification of three RA receptors (RAR alpha, beta and gamma) as members of the nuclear receptor superfamily led to important insights into the molecular mechanism of action of retinoids. The nuclear receptors, that also include receptors for steroid hormone, vitamin D3 and thyroid hormone act as ligand-inducible transcription factors and are characterized by the presence of two well conserved DNA- and hormone-binding domains. One of the most intriguing properties of RA is its ability to induce in vivo differentiation of acute promyelocytic leukaemia (APL) cells into mature granulocytes, leading to morphological complete remissions. We and others have shown that the t(15;17) translocation specifically associated with APL fuses an as yet unidentified gene, named PML, to the retinoic acid receptor alpha locus. The resulting PML-RAR alpha hybrid protein that retains most of the functional domains of parental proteins exhibits altered transactivating functions when compared to the wild-type receptor; however the biological significance of this property in the transforming phenotype is still obscure. PML, whose function is unknown, belongs to a novel family of nuclear proteins characterized by the presence of a Cys/His-rich motif, named a RING finger, that include RNA-binding proteins, transcription factors and oncoproteins. A dimerization domain within PML is able to mediate the formation of PML-RAR alpha homodimers that can bind to target sequences with distinct DNA binding properties if compared with RAR alpha.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The t(15;17) translocation in acute promyelocytic leukemia. 767 45

Minimal residual disease (MRD) was prospectively monitored at the 10(-5) level by the reverse transcriptase-polymerase chain reaction (RT-PCR) of PML-retinoic acid receptor alpha (RARA) transcripts from 27 acute promyelocytic leukemia (APL) patients who achieved complete remission (CR) with all-trans retinoic acid and chemotherapy (previously untreated patients, 15; refractory to chemotherapy or relapsed, 12). The RNA quality from bone marrow cells was firstly assessed by gel electrophoresis to avoid false negativity because of the fragility of the APL cells and the PML-RARA transcripts. In 12 of 15 untreated patients, RT-PCR became negative during consolidation and intensification therapy 4-16 months after the initiation of therapy, whereas it remained positive in nine of 12 refractory patients. At the end of therapy, RT-PCR was negative in 14 patients and positive in 13 patients. The former patients remained in CR at median follow-up of 9 months after the end of therapy. In the latter, however, 10 patients relapsed at a median of 5 months after the end of therapy. These results suggest that the RT-PCR assay can evaluate the quality of CR in APL and predict subsequent relapse.
Leukemia 1995 Apr
PMID:Prognostic significance of the RT-PCR assay of PML-RARA transcripts in acute promyelocytic leukemia. The Leukemia Study Group of the Ministry of Health and Welfare (Kouseisho). 772 89

Altered sub-nuclear localisation of the nuclear body-associated PML protein in acute promyelocytic leukaemia, has been proposed to contribute to leukaemogenesis. We have recently shown that PML is a primary target gene of interferons. Here, it is shown that PML has growth suppressive properties and displays an altered expression pattern during human oncogenesis. PML is widely expressed in cell-lines and is cell-cycle regulated. Overexpression of the protein induces a sharp reduction in growth rates in vitro and in vivo. In contrast with cell-lines, in normal tissues (including those that rapidly proliferate) only a few cells have detectable PML levels. However, these can be upregulated by soluble factors (e.g. IFN, estrogens). Human epithelial tumors show a gradual increase of PML levels as the lesion progresses from benign dysplasia to carcinoma. A similar induction is found in the surrounding stroma and vessels, which likely results from paracrine interactions. Strikingly, when malignant cells turn invasive, they loose PML expression, while expression is conserved in the stromal compartment. These observations point to the existence of a consistent deregulation in the expression of the PML growth-suppressor during human oncogenesis.
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PMID:The PML growth-suppressor has an altered expression in human oncogenesis. 773 82

The retinoid receptors belong to a large superfamily of ligand-inducible transcription factors that include the steroid, vitamin D and thyroid hormone receptors, the peroxisome proliferator-activated receptor, the insect edysteroid receptor, and a number of orphan receptors whose ligands are unknown. All nuclear receptors have several well-characterized structural domains, including a conserved DNA-binding domain, and a ligand binding domain at the carboxyl terminus of the receptor. The RAR and RXR classes of nuclear retinoic acid receptors are each composed of alpha, beta and gamma subtypes with more than one isoform for each receptor subtype. Data from many investigators suggest there are RAR- and RXR-dependent gene pathways, and that the individual receptor subtypes may control distinct gene expression patterns. In addition, RXR has been found to heterodimerize with other nuclear receptors to form active transcriptional complexes, which influence the activity of a variety of gene pathways important in growth and differentiation. As a result, retinoids have been useful clinical agents in Dermatology and Oncology. However, upon prolonged exposure to retinoic acid, resistance to retinoids has often been encountered both in the clinical setting and in long-term cell culture (HL60R and RAC65 cells). In the latter case, retinoid resistance has been associated with a mutation in the RAR gene which transcribes a RAR receptor truncated at the C-terminal end. These mutated RAR receptors exhibit a reduced affinity for retinoic acid while retaining the ability to bind to a retinoic acid response element on DNA. As a result, these mutant receptors exhibit dominant-negative activity by binding to the DNA without activating transcription and by competing with other receptors for sites on the response element. In fact, dominant-negative activity may be very important in the development of many neoplastic diseases, including acute promyelocytic leukemia (APL), where a t(15;17) chromosomal translocation fuses the PML gene to the RAR gene, to produce a PML-RAR fusion protein in large excess in the cell. However, retinoid resistance in the patient is most probably the result of pharmacokinetic problems, whereby, with continuous retinoid treatment, the plasma levels of retinoic acid gradually decrease to below that required to maintain differentiation of leukemic cells in vivo. A major challenge for drug discovery is to design a drug which circumvents these pharmacokinetic problems either by designing novel drug delivery systems or by employing retinoids which do not bind to CRABP, such as 9-c-RA.(ABSTRACT TRUNCATED AT 400 WORDS)
Leukemia 1994
PMID:The retinoid receptors. 780 17

The current treatment of acute promyelocytic leukemia (APL, also called AML3 subtype) is focused on differentiating agents such as the vitamin A derivative all-trans retinoic acid (ATRA). This agent is a novel and very promising therapy for this disease characterized cytogenetically by a translocation t(15;17)(q21;q22) involving the alpha retinoic acid receptor on chromosome 17 and the PML gene on chromosome 15. Clinical trials have demonstrated that ATRA followed by or combined with conventional chemotherapy may be more beneficial than chemotherapy for inducing complete remission. Unfortunately, ATRA as a single agent, does not appear able to maintain patients in remission (median 5 months), and when relapse occurs resistance to a second induction of ATRA therapy is observed in almost all cases. Recently our laboratory investigated whether specific features of the AML3 cells at relapse could explain the in vivo resistance observed. We have demonstrated that AML3 patients' cells (from four patients) at relapse show high levels of CRABP, a cytosolic retinoic acid binding protein and this protein was not detected prior to ATRA therapy. Relapse-AML3 cells (n = 12) showed reduced differentiation induction when compared with 'virgin'-AML3 cells. Results from this study suggest that CRABP could modulate ATRA cellular concentrations reaching the nucleus. This induced ATRA hypercatabolytic state should be monitored during consolidation therapy and at relapse by evaluating CRABP and RA metabolite levels, in order to detect ATRA resistance in patients with AML3.
Leukemia 1994
PMID:In vitro all-trans retinoic acid (ATRA) sensitivity and cellular retinoic acid binding protein (CRABP) levels in relapse leukemic cells after remission induction by ATRA in acute promyelocytic leukemia. 781 31

In an ongoing study, we treated 79 patients with a molecular diagnosis of acute promyelocytic leukemia (APL) using all-trans retinoic acid (RA) for remission induction. Newly diagnosed patients received cytotoxic chemotherapy for consolidation, and previously treated patients received extended all-trans RA therapy, or a radionuclide-conjugated monoclonal antibody as post-remission treatment. Unlike studies in Europe, full-dose chemotherapy was not given during induction for patients who developed leukocytosis. Overall, 43 of 49 newly diagnosed patients (88%) and 25 of 30 previously treated patients (83%) achieved complete remission. We did not encounter de novo resistance to all-trans RA in any patient who was positive for PML/RAR-alpha rearrangements by reverse transcription polymerase chain reaction analysis. Ten patients died during induction from intracranial or pulmonary hemorrhage (six patients) or the 'retinoic acid syndrome' (four patients). The use of leukapheresis or low-dose chemotherapy (hydroxyurea or cytosine arabinoside) for drug-induced leukocytosis did not decrease early mortality. Compared to historical controls, early mortality was not affected by treatment with all-trans RA; however, both relapse-free and overall survival were significantly increased. Maintenance therapy with all-trans RA was associated with short remission duration, and relapses while taking the drug were universally associated with resistance to further retinoid treatment. We conclude that the use of all-trans RA for remission induction, with or without full-dose chemotherapy, has significantly increased the survival of patients with APL. While early mortality has not yet been reduced, the avoidance of full-dose chemotherapy during induction has significantly reduced early morbidity. The major outstanding clinical issue is the development of strategies that maximize safety in high-risk patients for whom intracranial hemorrhage remains the major cause of death.
Leukemia 1994
PMID:Treatment of acute promyelocytic leukemia with all-trans retinoic acid: an update of the New York experience. 781 34

A rearrangement between the PML and RAR-alpha genes underlies the acute promyelocytic leukemia (APL)-specific t(15;17) translocation, leading to the production of a chimeric mRNA. Recent development of a reverse-transcription polymerase chain reaction (RT-PCR) assay for the PML/RAR-alpha hybrid has proven useful for rapid diagnosis and monitoring of minimal residual disease (MRD) in APL patients. Preliminary studies in which the prognostic significance of RT-PCR was evaluated indicate that this test may identify patients at high risk of relapse.
Leukemia 1994
PMID:Monitoring of treatment outcome in acute promyelocytic leukemia by RT-PCR. 781 41


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