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

2-Chloroethyl-N-nitrosoureas are highly active anti-neoplastic drugs in clinical use for many years. Therapy with these DNA cross-linking agents is limited by their toxic side effects, cumulative and delayed bone marrow toxicity being the main dose-limiting one. Since the intrinsic anti-tumour activity of the nitrosourea group is very high, coupling to appropriate carrier molecules represents a challenge for target-orientated chemotherapy. Many human tumours contain receptors for steroid hormones. Therefore, 2-chloroethyl-N-nitroso-carbamoyl(CNC)-amino acid derivatives have been developed that are linked to steroid hormones. In the series of oestradiol (E2)-linked analogues CNC-L-alanine-E2-17-ester was significantly superior to other E2-linked congeners and to the unlinked equimolar mixture when tested against hormone-dependent N-methyl-N-nitrosourea-induced mammary carcinoma of the rat. Relevance of E2 receptor contents for therapy with E2-linked drugs is evidenced by loss of superiority of this analogue in hormone-independent mammary carcinomas. Some androgen-linked CNC-amino acids showed substantial affinity to the androgen receptor and in part also to the progesterone receptor. A preliminary study in rat leukaemia L5222 revealed the CNC-L-alanine-dihydrotestosterone-17-ester to be highly active. Studies with hormone-dependent tumour models are under way.
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PMID:Development of more selective anti-cancer nitrosoureas. 336 4

Clonal analysis of FACS-purified primitive hematopoietic stem cells and of their progeny as assessed by the progenitors obtained from long-term cultures requires PCR-based approaches, mainly because of the low number of cells available. We have developed a non-radioactive androgen receptor (AR) assay which allows a simple and quantitative evaluation of the clonality of hematopoietic cells and progenitors. In this approach 5' AR primer is labelled by fluorescein and the amplified product is run on a sequencing gel which allows evaluation of the intensity of the fluorescent peaks generated. A computer software then analyzes the reduction of the intensity of the peaks on HpaII-digested samples. In order to determine the feasibility of the technique, we analyzed the clonality of leukemic cells from a patient with an acute-phase CMML which showed a typical clonal pattern of her leukemic DNA sample (WBC = 300 x 10(9)/I) using phosphoglycerate kinase (PGK) analysis. The same sample was then analyzed with either radioactive- or fluorescein-labelled AR primers, showing a typical clonal pattern (complete disappearance of one allele after HpaII digestion). A short-term clonogenic assay was then set up on methylcellulose and clonogenic progenitors were individually analyzed. All 24 colonies tested showed a typical clonal pattern with the disappearance of the same allele on each sample after HpaII digestion, indicating that they all derived from the same leukemic stem cell. Using this approach we then analyzed 94 patients with several hematologic malignancies and quantification of their fluorescent peaks. Fifty-four percent of the patients were clearly heterozygous (ie, a difference of > or = 2 CAG repeats was present between the two copies of the gene) and could be analyzed in an automatic sequencer using the fluorescent primers. Bone marrow mononuclear cells from all patients with acute myeloid leukemia (AML) showed a clonal or oligoclonal pattern at diagnosis whereas a polyclonal pattern was seen when remission was obtained. Similarly, out of 21 patients with a diagnosis of myelodysplastic syndrome (MDS), a clonal pattern was demonstrated in 10 whereas an oligoclonal or non-clonal pattern was shown in 11. These results show that this non-radioactive and safe technology can now be used on a large scale to evaluate the clonality of highly purified hematopoietic stem cells and their progenitors in hematopoietic malignancies and this might allow new insights into the targets of clonal amplification.
Leukemia 1995 Sep
PMID:Quantitative non-radioactive clonality analysis of human leukemic cells and progenitors using the human androgen receptor (AR) gene. 765 27

Quantification of X-chromosome inactivation patterns (XCIPs) using PCR amplification of the human androgen receptor (HUMARA) locus is potentially valuable in a range of haematological disorders. Of 236 females screened, 203 (86%) were heterozygous. For quantitative XCIPs it was necessary to limit the number of PCR cycles to 20 to reduce preferential amplification of shorter alleles. The optimized PCR method was compared with Southern blotting results using either PGK, HPRT or M27beta in 51 haematologically normal females and blast cells from 27 patients with acute myeloid leukaemia (AML). Reproducible XCIP results were obtained in all 78 samples using digestion with Hpa II prior to amplification (median difference in duplicate values 3%, range 0-17%) and they correlated well with Southern blotting results, r=0.966. Greater variability was observed in the results using Hha I digestion (median difference 4%, range 0-48%). There were marked inconsistencies in repeated analyses of three AML samples and although the HUMARA-Hha I results correlated well overall with Southern blotting in the remaining 75 samples (r=0.922), in nine samples there were still discrepancies with > or = 20% difference between the two values. These results suggest that PCR analysis of the HUMARA locus in Hpa II-digested DNA is suitable for the quantification of XCIPs in haematological samples but results with Hha I should be treated with caution.
Leukemia 1996 Feb
PMID:Quantification of X-chromosome inactivation patterns in haematological samples using the DNA PCR-based HUMARA assay. 863 49

B-cell leukemia/lymphoma (bcl-2) expression can override the apoptosis development in lymphoid and hormonally regulated tissue-like breast. The presence of estrogen receptor (ER), progesterone receptor (PR), and androgen receptor (AR) have revealed in breast carcinomas, but they have not been correlated to the bcl-2 protein expression and DNA fragmentation markers. We evaluated the immunohistochemical expression of bcl-2 protein and hormonal receptors (ER, PR, AR) and differentiation grade in 37 infiltrating ductal carcinomas of the breast for which frozen tissues were available for DNA extraction. The immunohistochemical reaction for bcl-2 was considered positive if more than 50% of neoplastic cells had intense cytoplasmic staining, whereas for steroid receptor evaluation Battifora's criteria were used. The DNA was extracted according to the phenol-chloroform procedure and used for bcl-2 gene rearrangement study of the major breakpoint region (Southern blot) and for membrane-based end-labeling using digoxigenin-labeled nucleotides and E. coli DNA polymerase I (Klenow fragment). The results were quantified by three different observers. Low-grade carcinomas were positive for bcl-2 protein (27/28, 96.4%) and ER (15/28, 53.6%), whereas the remaining neoplasms were negative for bcl-2 (9/9, 100.0%) and ER (8/9, 53.6%) (p < 0.001). No statistically significant differences were revealed at the bcl-2, PR and AR comparisons. The Southern blot analysis for bcl-2 major breakpoint region showed neither rearrangement nor genetic amplification (densitometric study). Only the membrane-based end-labeling of DNA fragments showed correlation with bcl-2 protein and ER expressions: all except one bcl-2-negative tumor and two bcl-2-positive tumors had positive labeling using 7 pg of DNA at dot blot analysis (p < 0.002). The bcl-2 protein expression would allow both proliferation and cell progression by blocking apoptosis in well-differentiated, ER-positive breast carcinomas. In these neoplasms, DNA fragmentation as a molecular marker of apoptosis was prevented by bcl-2 expression.
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PMID:Bcl-2 expression and DNA fragmentation in breast carcinoma, pathologic and steroid hormone receptors correlates. 936 Aug 41

Clonality analysis using the polymorphism of X-linked genes, such as the phosphoglycerate kinase (PGK), hypoxanthine phosphoribosyl transferase (HPRT) genes and CAG repeat of the human androgen receptor (HU-MARA) gene and the hypervariable DXS255 gene have been widely used in the assessment of many hematologic diseases. Monoclonal hematopoiesis was clearly demonstrated in myelodysplastic syndromes (MDS), myeloproliferative disorders (MPD) and leukemia by the X-inactivation analysis. Previous studies also found a higher incidence of monoclonality in aplastic anemia and 'clonal remission' in acute leukemia. However, recent studies have shown that clonal hematopoiesis in aplastic anemia or remission of leukemia is rarer than previously thought when skewed X-inactivation was extensively ruled out by comparison with T-lymphocytes as an internal control. However, a polyclonal pattern obtained by X-inactivation cannot exclude the possibility of a small clonal cell population presenting in aplastic anemia. However, recent studies have demonstrated that residual polyclonal (possibly normal) hematopoietic progenitor cells can be detected in the bone marrow of MDS and MPD patients whose peripheral blood granulocytes showed a monoclonal pattern. This may suggest a novel approach to treatment of these diseases.
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PMID:Clonality in hematopoietic disorders. 947 67

Microsatellites are unique highly polymorphic and informative genetic markers dispersed in the human genome. Their detection by PCR is rapid and a wide variety of DNA sources including archival material are available for diagnostic purposes. Microsatellite typing of haematological neoplasms may be applied to the search for loss of heterozygosity at loci possibly harbouring tumour suppressor genes, for example in acute lymphoblastic leukaemia. The technique may detect submicroscopical chromosomal deletions which are not visible in the leukaemic karyotype. RER+ tumours exhibiting microsatellite instability appear to be rare among haematological cancers with the possible exception of lymphoid tumours in immunosuppressed patients and lymphomas derived from mucosa-associated lymphoid tissue. An X-chromosomal microsatellite near the human androgen receptor gene (HUMARA) may be used for clonal X-inactivation analysis. Microsatellites therefore represent a collection of powerful genetic markers suitable to tackle questions relevant to basic research and clinical problems in leukaemia and lymphoma.
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PMID:Microsatellite markers in leukaemia and lymphoma: comments on a timely topic. 949 99

X chromosome inactivation and polymorphism of the human androgen receptor (HUMARA) gene has been applied for analyzing the clonality of blood cells. In the present study, the clonal relationship was investigated between peripheral blood polymorphonuclear cells (PMNCs) and marrow progenitor cells and the origin of ringed sideroblasts in patients with refractory anemia with ring sideroblasts (RARS) by polymerase chain reaction (PCR) of HUMARA gene. The X-inactivation patterns of circulating PMNCs and T lymphocytes as well as individual granulocyte colonies grown in vitro from bone marrow cells were analyzed. The development of ringed sideroblasts in erythroid colonies by iron staining and their X-inactivation pattern were also examined. All three RARS patients showed monoclonal PMNCs. In granulocyte colonies, however, two different X-inactivation patterns were observed in all patients, indicating that non-clonal progenitor cells remained in the bone marrow. All erythroid colonies consisted of ringed sideroblasts exclusively showed one pattern dominant in those of PMNCs. Our findings suggest that non-clonal progenitor cells persist in some RARS cases, that erythroid progenitors show mosaicism, and that ringed sideroblasts may be derived from an abnormal clone involved in the pathogenesis of this disease.
Leukemia 1999 Jan
PMID:Clonality analysis of refractory anemia with ring sideroblasts: simultaneous study of clonality and cytochemistry of bone marrow progenitors. 1004 48

We previously reported that the hypermethylation of the p15INK4B gene promoter was frequently observed in myelodysplastic syndromes (MDS), and that it may be associated with disease progression. An unanswered question is whether p15INK4B gene methylation is restricted to undifferentiated blastic cells, or whether differentiated cells such as granulocytes or erythrocytes of MDS origin also harbor this epigenetic alteration. In this study, we analyzed the methylation status of the p15INK4B gene in MDS by the methylation-specific PCR (MSP) method, which is more sensitive than Southern blotting. The bone marrow mononuclear cells (BM-MNCs) of 23 MDS patients were analyzed, and six of them showed p15INK4B methylation. Progenitor assay with methylcellulose medium was also performed in all patients. In two of the six patients with p15INK4B-methylated BM-MNCs, erythroid and/or non-erythroid colonies formed were subjected to molecular analysis. Colonies with and without p15INK4B methylation were detected in both patients. Furthermore, X-chromosome inactivation (XCI) pattern of each colony was simultaneously determined by MSP-based human androgen receptor gene analysis (HUMARA-MSP), and all p15INK4B-methylated colonies showed the same XCI pattern, which was dominant among the colonies, while p15INK4B-unmethylated colonies showed both patterns of XCI, in each of the two patients. We then examined the methylation status of the p15INK4B gene of granulocyte (PB-PMN) fractions from 10 patients with available peripheral blood cells. In all four patients with p15INK4B-methylated BM-MNCs, their PB-PMNs showed p15INK4B methylation. These results suggest that p15INK4B methylation in hematopoietic cells in MDS patients is restricted to the MDS clone but not necessarily to blast cells.
Leukemia 2000 Apr
PMID:Methylation status of the p15INK4B gene in hematopoietic progenitors and peripheral blood cells in myelodysplastic syndromes. 1076 43

Nuclear receptors comprise a family of transcription factors that regulate gene expression in a ligand dependent manner. They can activate or repress target genes by binding directly to DNA response elements as homo- or hetero-dimers or by binding to other classes of DNA-bound transcription factors. These activities have been linked to the formation of complexes with molecules that appear to serve as coactivators or corepressors, causing local modification of chromatin structure in order to regulate expression of their target genes. Several members of nuclear receptor family are directly associated with human malignancies including breast cancer, prostate cancer and leukaemia. The pathogenesis of each of these diseases is underpinned by the activities of a member of the superfamily; estrogen receptor-alpha (ER alpha) in breast cancer, androgen receptor (AR) in prostate cancer, and retinoic acid receptor alpha (RAR alpha) in acute promyelocytic leukaemia.
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PMID:Modulation of nuclear receptor dependent transcription. 1241 47

DNA methylation provides a major epigenetic code (besides histone modification) of the lineage- and development-specific genes (such as regulators of differentiation in the hematopoietic lineages) that control expression of normal cells. However, DNA methylation is also involved in malignancies because aberrant methylating gene activity occurs during leukemic transformation. Thus, genes such as tumor suppressor genes, growth-regulatory genes, and adhesion molecules are often silenced in various hematopoietic malignancies by epigenetic inactivation via DNA hypermethylation. This inactivation is frequently seen not only in transformed cell lines but also in primary leukemia cells. Because this defect is amenable to reversion by pharmacologic means, agents that inhibit DNA methylation have been developed to specifically target this hypermethylation defect in leukemia and preleukemia cases. The most clinically advanced agents, the azanucleosides 5-azacytidine and 5-aza-2'-deoxycytidine (decitabine), were discovered more than 25 years ago, when their methylation-inhibitory activities, even at low concentrations, became apparent. Although both of these agents, like cytarabine, had been clinically used until then at high doses, the redevelopment of these agents for low-dose schedules has revealed very interesting clinical activities for treating myelodysplasia (MDS) and acute myeloid leukemia (AML). Because these diseases occur mostly in patients over 60 years of age, low-dose schedules with these compounds provide a very promising approach in such patient groups by virtue of their low nonhematologic toxicity profiles. In the present review, we describe the development of treatments that target DNA hypermethylation in MDS and AML, and clinical results are presented. In addition, pharmacologic DNA demethylation may be viewed as a platform for biological modification of malignant cells to become sensitized (or resensitized) to secondary signals, such as differentiating signals (retinoids, vitamin D3) and hormonal signals (eg, estrogen receptor in breast cancer cells, androgen receptor in prostate cancer cells). Finally, an in vitro synergism between the reactivating potency of demethylating agents and inhibitors of histone deacetylation has been tested in several pilot studies of AML and MDS treatment. Finally, gene reactivation by either group of compounds results in therapeutically meaningful reactivation of fetal hemoglobin in patients with severe hemoglobinopathies, extending the therapeutic range of derepressive epigenetic agents to nonmalignant hematopoietic disorders.
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PMID:DNA methylation as a therapeutic target in hematologic disorders: recent results in older patients with myelodysplasia and acute myeloid leukemia. 1548 40


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