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 biological activity and cellular metabolism of ZD1694, a novel folate-based thymidylate synthase (TS) inhibitor, were analyzed in a human leukemia cell line, MOLT-3, and its antifolate-resistant sublines with different mechanisms of resistance to methotrexate (MTX), trimetrexate (TMQ) and N10-propargyl-5,8-dideazafolic acid (CB3717). MOLT-3/CB3717(40), which was selected for CB3717 resistance, demonstrated impaired membrane drug transport via reduced folate carrier (RFC) and lower accumulation of [3H]ZD1694-polyglutamates in the cells with a shift in the polyglutamate distribution profile to shorter chain length polyglutamates, indicating an alteration in polyglutamation capacity in this subline. Impaired RFC and reduced rate of polyglutamation could explain the cross-resistance (12-fold) of this subline to ZD1694. On the other hand, there was little or no cross-resistance to this drug in a subline (MOLT-3/TMQ800) reportedly resistant to TMQ through impaired membrane transport for TMQ and an increase in dihydrofolate reductase (DHFR) activity. Total amount of ZD1694 polyglutamated to a level higher than diglutamate was approximately 1.7-fold higher in the TMQ-resistant cells than that in the parent cells, but a low degree of increase in TS activity in the cells counteracted the supposed increase in sensitivity to ZD1694. MOLT-3/TMQ800-MTX10000 cells, which were established by sequential exposure of the TMQ-resistant cells to MTX and were previously shown to amplify mutated DHFR with low affinity for MTX, showed a decreased accumulation of polyglutamated ZD1694 as compared with the parent line and this was consistent with cross-resistance to ZD1694 in this subline. Overproduction of variant DHFR scarcely influenced the sensitivity to this drug. These results indicate that ZD1694 could overcome antifolate resistance through a mechanism such as amplified DHFR activity, and the biological activity of this drug against the cells paralleled the amount of polyglutamated drug inside the cells. Determination of polyglutamation capacity in tumor cells may allow prediction of sensitivity to this drug.
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PMID:Biological activity and intracellular metabolism of ZD1694 in human leukemia cell lines with different resistance mechanisms to antifolate drugs. 869 29

The types of folates used during the development of resistance to methotrexate have been suggested to play an important role in the mechanisms of established resistance. In this study, effects of reduced and oxidized folates on the development of resistance to a thymidylate synthase (TS) inhibitor, N10-propargyl-5, 8-dideazafolic acid (CB3717), were examined in the human leukemia cell line MOLT-3. MOLT-3 cells were made resistant to CB3717 by soft-agar cloning in RPMI-1640 medium with either pteroylglutamic acid (PGA) or a more physiological folate (10 nM leucovorin). A 40-fold CB3717-resistant subline developed in PGA (MOLT-3/CB3717(40)-PGA) showed amplification of the TS gene with a concomitant increased level in the gene expression. A 200-fold CB3717-resistant subline (MOLT-3/CB3717(200)-PGA), which was derived from MOLT-3/CB3717(40)-PGA, showed further enhancement of amplification of the TS gene. In contrast, even a 200-fold CB3717-resistant subline developed in leucovorin (MOLT-3/CB3717(200)-LV) showed neither amplification nor overexpression of the TS gene. Both MOLT-3/CB3717(200)-PGA and MOLT-3/CB3717(200)-LV cells showed decreased membrane transport of PGA as well as methotrexate. These results suggest that the types of folates used during the development of CB3717 resistance may play a role in resistance, and that impaired transport of PGA, in CB3717-resistant MOLT-3 cells developed in PGA, might have accelerated amplification of the TS gene.
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PMID:Amplification of the thymidylate synthase gene in an N10-propargyl-5,8-dideazafolic-acid-resistant human leukemia, MOLT-3 cell line developed in pteroylglutamic acid, but not in leucovorin. 889 75

Cytotoxicity of trimetrexate (TMQ), a lipophilic dihydrofolate reductase inhibitor, was examined in antifolate-resistant human T-cell leukemia cell lines developed in oxidized or reduced folate. An approximately 60-fold methotrexate (MTX)-resistant subline was developed in oxidized folate (pteroylglutamic acid: PGA) (CCRF-CEM/MTX60-PGA) from human T-cell leukemia cell line CCRF-CEM; this line exhibited impaired membrane transport of the drug. Further enhancement of MTX resistance resulted in selection of an approximately 5000-fold MTX-resistant subline (CCRF-CEM/ MTX5000-PGA), which showed increased dihydrofolate reductase activity due to gene amplification in addition to further impairment of MTX transport. An approximately 140-fold MTX-resistant subline, and then a 1500-fold MTX-resistant subline were developed in reduced folate (10 nM leucovorin) (CCRF-CEM/MTX140-LV and CCRF-CEM/MTX1500-LV); they exhibited increased dihydrofolate reductase due to gene amplification accompanied by increased intracellular drug accumulation of MTX. While CCRF-CEM/MTX140-LV and CCRF-CEM/MTX1500-LV cells showed cross-resistance to TMQ, CCRF-CEM/MTX60-PGA and CCRF-CEM/MTX5000-PGA cells were at least as sensitive to TMQ as the parent cells. TMQ was more potent against approximately 200-fold N10-propargyl-5,8-dideazafolic-acid (CB3717)-resistant human T-cell leukemia MOLT-3 sublines developed in PGA (MOLT-3/CB3717(200)-PGA) or leucovorin (MOLT-3/CB3717(200)-LV), as compared to the parent cells; MOLT-3/CB3717(200)-PGA and MOLT-3/CB3717(200)-LV cells were resistant to CB3717 by virtue of impaired transport, only the former possessing gene amplification of thymidylate synthase. The cytotoxicity of TMQ in both MOLT-3/CB3717(200)-PGA and MOLT-3/CB3717(200)-LV cells was reduced by addition of leucovorin in a dose-dependent manner, suggesting intracellular folate deficiency as a cause of TMQ sensitivity. These results demonstrate that TMQ overcomes transport-impaired antifolate resistance, irrespective of gene amplification of dihydrofolate reductase or thymidylate synthase. Types of folate used during the development of antifolate resistance seem to be important in relation to the mechanism of TMQ responsiveness as well as that of antifolate resistance.
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PMID:Cytotoxicity of trimetrexate against antifolate-resistant human T-cell leukemia cell lines developed in oxidized or reduced folate. 936 39

1-[(2-Hydroxyethoxy)methyl]-5-fluorouracil (HEMFU) and 1-[(1,3-dihydroxy-2-propoxy)methyl]-5-fluorouracil (DHPFU) were prepared by alkylation of the di-O-TMS derivative of 5-fluorouracil and phosphorylated with the use of the wheat shoot phosphotransferase system to their monophosphates, HEMFUMP and DHPFUMP. 1-(2-Phosphonylmethoxyethyl)-5-fluorouracil (PMEFU) was obtained by condensation of diethyl-2-chloroethoxymethanephosphonate with 5-fluorouracil and cleavage of the alkylphosphoester with trimethylbromosilane. Inhibition of highly purified thymidylate synthase from mouse tumour Ehrlich carcinoma and leukemia L1210 cells by each of the nucleotide analogues, DHPFUMP, PMEFU and HEMFUMP, and of L5178Y mouse leukemia cell growth by the nucleoside (HEMFU) analogue, were studied. DHPFUMP proved to be the strongest inhibitor, non-competitive vs dUMP, with K(i)app 2.8 microM for time-independent interaction with the enzyme and N5,N10-methylenetetrahydrofolate (CH2H4PteGlu). In the presence of CH2H4PteGlu, DHPFUMP exhibited time-dependent inactivation of the enzyme, the inactivation rate plots being biphasic and pointing to Ki values in the microM range (10(3)-fold higher than for 5-fluoro-dUMP). HEMFUMP and PMEFU were much weaker inhibitors of the enzyme, with K(i)app values of 0.26 mM (non-competitive vs dUMP) and 30 mM (non-competitive vs dUMP), respectively. HEMFU, despite the weak interaction of its nucleotide analogue with the enzyme, proved to be a strong cell (L5178Y) growth inhibitor, with IC50 in the range 10(-5) M.
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PMID:Acyclic analogues of 5-fluoro-dUMP and 5-fluoro-2'-deoxyuridine: synthesis and inhibition of thymidylate synthase and tumour cell growth. 970 98

Six new B-ring analogues of the nonpolyglutamatable antifolate Nalpha-(4-amino-4-deoxypteroyl)-Ndelta-hemiphthaloy l-L-ornithine (PT523, 3) were synthesized with a view to determining the effect of modifications at the 5- and/or 8-position on dihydrofolate reductase (DHFR) binding and tumor cell growth inhibition. The 5- and 8-deaza analogues were prepared from methyl 2-L-amino-5-phthalimidopentanoate and 4-amino-4-deoxy-N10-formyl-5-deaza- and -8-deazapteroic acid, respectively. The 5,8-dideaza analogues were prepared from methyl 2-L-[(4-aminobenzoyl)amino]-5-phthalimidopentanoate and 2, 4-diaminoquinazoline-6-carbonitriles. The Ki for inhibition of human DHFR by the 5-deaza and 5-methyl-5-deaza analogues was about the same as that of 3 (0.35 pM), 11-fold lower than that of aminopterin (AMT, 1), and 15-fold lower than that of methotrexate (MTX, 2). However the Ki of the 8-deaza analogue was 27-fold lower than that of 1, and that of the 5,8-dideaza, 5-methyl-5,8-dideaza, and 5-chloro-5,8-dideaza analogues was approximately 50-fold lower. This trend was consistent with the published literature on the corresponding DHFR inhibitors with a glutamate side chain. In colony formation assays against the human head and neck squamous carcinoma cell line SCC25 after 72 h of treatment, the 5- and 8-deaza analogues were approximately as potent as 3, whereas the 5,8-dideaza analogue was 3 times more potent. 5-Methyl and 5-chloro substitution was also favorable, with the 5-methyl-5-deaza analogue being 2. 5-fold more potent than the 5-deaza analogue. However the effect of 5-methyl substitution was less pronounced in the 5,8-dideaza analogues than in the 5-deaza analogues. The 5-chloro-5,8-dideaza analogue of 3 was the most active member of the series, with an IC50 = 0.33 nM versus 1.8 nM for 3 and 15 nM for MTX. The 5-methyl-5-deaza analogue of 3 was also tested at the National Cancer Institute against a panel of 50 human tumor cell lines in culture and was consistently more potent than 3, with IC50 values in the low-nanomolar to subnanomolar range against most of the tumors. Leukemia and colorectal carcinoma cell lines were generally most sensitive, though good activity was also observed against CNS tumors and carcinomas of the breast and prostate. The results of this study demonstrate that B-ring analogues of 3 inhibit DHFR activity and tumor cell colony formation as well as, or better than, the parent compound. In view of the fact that 3 and its B-ring analogues cannot form polyglutamates, their high cytotoxicity relative to the corresponding B-ring analogues of AMT is noteworthy.
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PMID:Synthesis and potent antifolate activity and cytotoxicity of B-ring deaza analogues of the nonpolyglutamatable dihydrofolate reductase inhibitor Nalpha-(4-amino-4-deoxypteroyl)-Ndelta-hemiphthaloyl- L-ornithine (PT523). 985 98

GG-62 is a cell line previously thought to be derived from an atypical Ewing tumor (ET). Reverse-transcriptase polymerase chain reaction revealed an in-frame fusion between the Ewing sarcoma gene ( EWS) codon 325 and the activating transcription factor 1 gene ( ATF1) codon 65 which permits the production of chimeric EWS-ATF1 oncoproteins. We also identified the genomic breakpoint resulting from a reciprocal t(12;22)(q13;q12), which is the hallmark of malignant melanoma of soft parts (MMSP). We applied Affymetrix human cancer G110 arrays to compare the gene expression patterns of GG-62 and other cell lines derived from small blue round cell tumors of childhood. Hierarchical clustering of 463 differentially expressed genes distinguished GG-62 from the ETs, as well as the neuroblastomas, and revealed a cluster of 36 upregulated genes. Several of these genes are involved in signal transduction pathways that may be critical for maintaining cell transformation; some examples are avian erythroblastic leukemia viral oncogene homolog 3 ( ERBB3), neuregulin 1 ( NRG1), fibroblast growth factor 9 ( FGF9), and fibroblast growth factor receptor-1 ( FGFR1). Furthermore, genes near the chromosome-12q13 breakpoint exhibited increased expression of GG-62 including ERBB3, NR4A1 (nuclear receptor subfamily 4, group A, member 1), cyclin-dependent kinase 2 ( CDK2), and alpha 5 integrin ( ITGA5). Altogether our findings demonstrate the MMSP derivation of GG-62 and may shed light on the mechanisms of tumorigenesis in this rare disease.
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PMID:Characterization of the malignant melanoma of soft-parts cell line GG-62 by expression analysis using DNA microarrays. 1202 21

Tumors of thyroid follicular cells provide a very interesting model to understand the development of human cancer. It is becoming apparent that distinct molecular events are associated with specific stages in a multistep tumorigenic process with good genotype/ phenotype correlation. For instance, mutations of the gsp and thyroid-stimulating hormone receptor genes are associated with benign hyperfunctioning thyroid nodules and adenomas while alterations of other specific genes, such as oncogenic tyrosine kinase alterations (RET/PTC, TRK) in papillary carcinoma and the newly discovered PAX8/peroxisome proliferator-activated receptor gamma rearrangement, are distinctive features of cancer. Although activating RAS mutations occur at all stages of thyroid tumorigenesis, evidence is accumulating that they may also play an important role in tumor progression, a role that is well documented for p53. Environmental factors (iodine deficiency, ionizing radiations) have been shown to play a crucial role in promoting the development of thyroid cancer, influencing both its genotypic and phenotypic features. It is possible that the follicular thyroid cell has unique ways to respond to DNA damage. Similarly to leukemia or sarcomas (and unlike most epithelial cancers), numerous specific rearrangements are being discovered in thyroid cancer suggesting preferential activation of DNA repair instead of cell death programs after environmentally induced genetic alterations.
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PMID:Molecular pathobiology of thyroid neoplasms. 1266 46

Previous studies showed that progesterone receptor (PR), one of the hormone receptor superfamily, was only connected with the sex-correlated cancers such as breast cancer, endometrial cancer, prostate cancer, etc. This article deals with the PR gene in leukemia. We investigated the methylation status and the expression of the two different PR isoforms, PRA and PRB, in three leukemia cancer cell lines using methylation-specific polymerase chain reaction (MSP-PCR) and reverse transcription-PCR. The correlation of PR methylation and expression together with DNA methyltransferase (DNMT1) was further studied. We found that DNMT1 is required to maintain CpG methylation and aberrant gene silencing of PR gene in human leukemia cancer cells. The activity of 5-aza-2'-deoxycytidine in demethylation and gene reactivation may be through depleting cellular DNMT1 levels. In addition, extensive methylation of PRA and PRB was also observed in leukemia samples. Our results suggest that PR CpG island aberrant hypermethylation could be one molecular and genetic alteration in leukemia.
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PMID:Progesterone receptor gene inactivation and CpG island hypermethylation in human leukemia cancer cells. 1517 46

Nuclear receptors are ubiquitous eukaryotic ligand-activated transcription factors that modulate gene expression through varied interactions. However, the highly conserved functional sites known today seem insufficient to explain receptor specific recruitment of different coactivator and corepressor proteins and regulation of transcription. To search for new receptor-subtype specific functional sites, we applied difference evolutionary trace (difference ET) analysis to the ligand binding domain of steroid receptors, a subgroup of the nuclear receptor (NR) family. This computational approach identified a new functional site located on a surface opposite to currently known protein-protein interaction sites and distinct from the ligand binding pocket. Strikingly, the literature shows that in vivo variations at residues in the new site are linked to androgen resistance and leukemia, and our own targeted mutations to this site lower but do not eradicate transcriptional activation by estrogen receptor alpha (ERalpha), with reduced ligand binding affinity and SRC-1 interaction. Thus, these data demonstrate that this evolutionary important surface can function as an allosteric site that modulates some but not all receptor binding interactions. Evolutionary analysis further shows that this allosteric regulatory site is shared among all NRs from groups 2 (HNF4-like) and 4 (NGFIB-like), suggesting a role among many nuclear receptors. Its concave structure, hydrophobic composition, and residue variability among nuclear receptors further suggest that it would be amenable for specific drug design. This highlights the power of evolutionary information for the identification of new functional sites even in a protein family as well studied as NRs.
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PMID:Evolutionary identification of a subtype specific functional site in the ligand binding domain of steroid receptors. 1683 8

In T-cell acute lymphoblastic leukemia (T-ALL) the cardiac homeobox gene NKX2-5 (at 5q35) is variously deregulated by regulatory elements coordinating with BCL11B (at 14q32.2), or the T-cell receptor gene TRD (at 14q11.2), respectively. NKX2-5 is normally expressed in developing spleen and heart, regulating fundamental processes, including differentiation and survival. In this study we investigated whether NKX2-5 expression in T-ALL cell lines reactivates these embryonal pathways contributing to leukemogenesis. Among 18 known targets analyzed, we identified three genes regulated by NKX2-5 in T-ALL cells, including myocyte enhancer factor 2C (MEF2C). Knockdown and overexpression assays confirmed MEF2C activation by NKX2-5 at both the RNA and protein levels. Direct interactions between NKX2-5 and GATA3 as indicated by co-immunoprecipitation data may contribute to MEF2C regulation. In T-ALL cell lines LOUCY and RPMI-8402 MEF2C expression was correlated with a 5q14 deletion, encompassing noncoding proximal gene regions. Fusion constructs with green fluorescent protein permitted subcellular detection of MEF2C protein in nuclear speckles interpretable as repression complexes. MEF2C consistently inhibits expression of NR4A1/NUR77, which regulates apoptosis via BCL2 transformation. Taken together, our data identify distinct mechanisms underlying ectopic MEF2C expression in T-ALL, either as a downstream target of NKX2-5, or via chromosomal aberrations deleting proximal gene regions.
Leukemia 2008 Mar
PMID:MEF2C is activated by multiple mechanisms in a subset of T-acute lymphoblastic leukemia cell lines. 1807 34


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