Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In addition to its inhibitory activity against viral DNA polymerases and reverse transcriptase, the acyclic nucleoside phosphonate 9-(2-phosphonylmethoxyethyl)adenine (PMEA) also markedly inhibits the replicative cellular DNA polymerases alpha, delta, and epsilon. We have previously shown that PMEA is a strong inducer of differentiation in several in vitro tumor cell models and has marked antitumor potential in vivo. To elucidate the molecular mechanism of the differentiation-inducing activity of PMEA, we have now investigated the effects of the drug on cell proliferation and differentiation, cell cycle regulation, and oncogene expression in the human erythroleukemia K562 cell line. Terminal, irreversible erythroid differentiation of PMEA-treated K562 cells was evidenced by hemoglobin production, increased expression of glycophorin A on the K562 cell membrane, and induction of acetylcholinesterase activity. After exposure to PMEA, K562 cell cultures displayed a marked retardation of S-phase progression, leading to a severe perturbation of the normal cell cycle distribution pattern. Whereas no substantial changes in c-myc mRNA levels and p21, PCNA, cdc2, and CDK2 protein levels were noted in PMEA-treated K562 cells, there was a marked accumulation of cyclin A and, most strikingly, cyclins E and B1. A similar picture of cell cycle deregulation was also observed in PMEA-exposed human myeloid THP-1 cells. However, in contrast to the strong differentiation-inducing activity of PMEA in K562 cells, the drug completely failed to induce monocytic maturation of human myeloid THP-1 cells. On the contrary, THP-1 cells underwent apoptotic cell death in the presence of PMEA, as demonstrated by prelytic, intracellular DNA fragmentation and the binding of annexin V to the cell surface. We hypothesize that, depending on the nature of the tumor cell line, PMEA triggers a process of either differentiation or apoptosis by the uncoupling of normally integrated cell cycle processes through inhibition of DNA replication during the S phase.
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PMID:9-(2-Phosphonylmethoxyethyl)adenine induces tumor cell differentiation or cell death by blocking cell cycle progression through the S phase. 1039 5

Water-soluble 20(S)-glycinate esters of two highly potent 10,11-methylenedioxy analogues of camptothecin (CPT) have been synthesized and evaluated for their ability to eradicate human breast cancer tumor xenografts. The glycinate ester moiety increases the water solubility of the 10,11-methylenedioxy analogues 4-16-fold. However, in contrast to CPT-11, a water-soluble CPT analogue that was recently approved for second line treatment of colorectal cancer, the 20(S)-glycinate esters do not require carboxylesterase for conversion to their active forms. The glycinate esters are hydrolyzed to their parent, free 20(S)-hydroxyl active analogues in phosphate buffer (pH 7.5) and in mouse and human plasma. The glycinate esters are also 20-40-fold less potent than CPT-11 in inhibiting human acetylcholinesterase. In vivo, we examined 20(S)-glycinate-10,11-methylenedioxycamptothecin, 20(S)-glycinate-7-chloromethyl-10,11-methylenedioxycamptothecin, and CPT-11. We found that the two 10,11-methylenedioxy analogues had antitumor activity against breast cancer xenografts that was comparable to that of CPT-11. Our results indicate that water-soluble 20(S)-glycinate esters of highly potent CPT analogues provide compounds that maintain biological activity, do not require interactions with carboxylesterases, and do not inhibit human acetylcholinesterase.
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PMID:Water soluble 20(S)-glycinate esters of 10,11-methylenedioxycamptothecins are highly active against human breast cancer xenografts. 1041 5

The natural product hypericin is a photosensitive polycyclic aromatic dione compound, which has been widely investigated because of its virucidal and antitumor properties. Although it has been suggested that singlet oxygen or a radical species might be responsible for its biological action, its mechanism of action remains unknown. Due to its amphiphilic characteristics, we considered the possibility that it might interact preferentially with partially unfolded proteins which exhibit exposed hydrophobic surfaces. We here demonstrate that hypericin binds to a molten globule species generated from Torpedo acetylcholinesterase, but not to the corresponding native enzyme. Irradiation with visible light, under aerobic conditions, causes chemical cross-linking of the catalytic subunits, to dimers and heavier species, under conditions where no cross-linking is observed for the native enzyme. Both anaerobiosis and sodium azide greatly reduce the extent of cross-linking, suggesting that singlet oxygen is responsible for the phenomenon. This agrees with our observation, using spin traps, that mainly singlet oxygen is produced by the complex of hypericin with the molten globule of acetylcholinesterase. Cross-linking is enhanced in the presence of liposomes to which the molten globule of acetylcholinesterase is quantitatively adsorbed. This may be due to high local concentrations of both hypericin and the protein resulting in close proximity, and hence in a high yield of cross-linking. Molten globule species are believed to be intermediates in both protein folding and translocation through biological membranes. Thus, hypericin may serve as a valuable tool for trapping such intermediates. This might also explain its therapeutic effectiveness toward virus-infected or tumor cells.
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PMID:Targeted cross-linking of a molten globule form of acetylcholinesterase by the virucidal agent hypericin. 1047 Dec 90

Apart from its catalytic function in hydrolyzing acetylcholine, acetylcholinesterase (AChE) affects cell proliferation, differentiation and responses to various insults, including stress. These responses are at least in part specific to the three C-terminal variants of AChE which are produced by alternative splicing of the single ACHE gene. 'Synaptic' AChE-S constitutes the principal multimeric enzyme in brain and muscle; soluble, monomeric 'readthrough' AChE-R appears in embryonic and tumor cells and is induced under psychological, chemical and physical stress; and glypiated dimers of erythrocytic AChE-E associate with red blood cell membranes. We postulate that the homology of AChE to the cell adhesion proteins, gliotactin, glutactin and the neurexins, which have more established functions in nervous system development, is the basis of its morphogenic functions. Competition between AChE variants and their homologs on interactions with the corresponding protein partners would inevitably modify cellular signaling. This can explain why AChE-S exerts process extension from cultured amphibian, avian and mammalian glia and neurons in a manner that is C-terminus-dependent, refractory to several active site inhibitors and, in certain cases, redundant to the function of AChE-like proteins. Structural functions of AChE variants can explain their proliferative and developmental roles in blood, bone, retinal and neuronal cells. Moreover, the association of AChE excess with amyloid plaques in the degenerating human brain and with progressive cognitive and neuromotor deficiencies observed in AChE-transgenic animal models most likely reflects the combined contributions of catalytic and structural roles.
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PMID:Structural roles of acetylcholinesterase variants in biology and pathology. 1049 Nov 13

The study included 82 patients with multiple myeloma (MM) to evaluate the diagnostic and prognostic significance of correlation between of levels of ceruloplasmin (CP), acetylcholinesterase (ACE) and total proteolytic activity (TPA) in blood serum and immunochemical pattern, tumor mass and response to chemotherapy. It was shown that CP, ACE and TPA determination may be used as additional markers to confirm therapeutic benefits, to timely detect relapse and to verify resistance to chemotherapy. It was also demonstrated that resultant decrease in CP and TPA and increase in ACE levels are reliable indicators of changes developing in MM course and remission fulfillment. High values for CP and low ones for ACE point to pathological activity. Both diagnostic and prognostic significance of the indices has been shown. The highest levels of CP and TPA in blood serum were identified in cases of A-myeloma and myeloma of Bence Jones while ACE concentrations in those patients were lower than in G-myeloma which correlated with median survival. Application of said assays might improve diagnosis, management and prognosis of MM.
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PMID:[Diagnostic and prognostic significance of blood-serum ceruloplasmin, acetylcholinesterase and total proteolytic activity in patients with multiple myeloma]. 1053 99

We evaluated the focal therapeutic effect of oily carcinostatic agents administered by transcatheter arterial infusion (TAI) as the initial therapy in patients with hepatocellular carcinoma in a randomized controlled clinical trial. Group A (19 patients) received 4 mg of styrene maleic acid neocarzinostatin in 4 ml of Lipiodol, and group B (18 patients) received 100 mg of epirubicin in 4 ml of Lipiodol via the tumor feeding arteries as peripherally as possible. The grade of Lipiodol accumulation and the tumor regression rate were determined 2 weeks after TAI by computerized tomography. Adverse effects within 2 weeks after TAI were evaluated by subjective signs and symptoms such as fever (maximum body temperature) and the frequency of shaking chills and abdominal pain, and by biochemical parameters such as albumin, prothrombin time, and aspartate and alanine aminotransferases. Lipiodol accumulation in the tumor was significantly greater in group A (12/19; 63.2% showing grade IV Lipiodol accumulation) than in group B (3/18; 16.7% showing grade IV) (P<0.05). The tumor regression rate was also significantly greater in group A (8/17; 47.1% showing more than 25% tumor regression) than in group B (1/13; 7.7% showing more than 25% tumor regression) (P<0.05). Although clinically significant elevations of aminotransferases and reductions of cholinesterase, and shaking chills were observed more often in group A than in group B (P<0.0001), these factors had little influence on the clinical outcome. Our results suggest that styrene maleic acid neocarzinostatin in Lipiodol exerts a more favorable focal therapeutic effect than does epirubicin in Lipiodol in the initial treatment of hepatocellular carcinoma.
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PMID:Focal therapeutic efficacy of transcatheter arterial infusion of styrene maleic acid neocarzinostatin for hepatocellular carcinoma. 1063 37

Cholinesterases are expressed non-synaptically during embryonic development, neoplasia and neurodegeneration. We have investigated the effects of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and, conversely, anti-AChE and -BChE antibodies and inhibitors on cell adhesion and neurite outgrowth in human neuroblastoma cells. Analysis of cholinesterase levels and isoforms in undifferentiated and differentiated cells indicated a significant rise in AChE levels on differentiation. This increase was related to both cell-associated and secreted enzyme, and was predominantly the G4 isoform. BChE levels and isoforms, on the other hand, showed no significant variation. Coating the tissue culture plate with AChE stimulated neurite outgrowth, while BChE had an anti-adhesive effect. Cell adhesion was affected by the BChE inhibitor, ethopropazine, and the AChE peripheral site inhibitor, BW284c51, but not by eserine which binds to the active site. This indicates that the adhesion function is non-cholinergic, a finding supported by the lack of effect of AE-2, a monoclonal antibody that inhibits AChE, on cell adhesion. Four out of a panel of nine anti-AChE antibodies inhibited adhesion to varying degrees. Of these antibodies, two are catalytic, with epitopes associated with the peripheral anionic site of AChE, and the remaining two have epitopes overlapping this site. Neither of the two anti-BChE antibodies used had any effect on adhesion. These results indicate the importance of AChE in neuroblastoma cell adhesion and neurite outgrowth, and suggest that the peripheral anionic site may be involved in these processes.
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PMID:Cholinesterases modulate cell adhesion in human neuroblastoma cells in vitro. 1115 47

The effect of malignant tumor growth on host's megakaryocytopoiesis and platelet production was studied in mice bearing transplantable Dalton's lymphoma. Tumor growth was paralleled by thrombocytosis, neutrophilia, and anemia. Platelet 51Cr half-life was normal but incorporation of 75Selenomethionine into circulating platelets was significantly enhanced in the tumor bearers suggesting stimulated thrombopoiesis while platelet life span remained unchanged. Megakaryocytes and their precursors, the small acetyl cholinesterase positive cells, were found in increased numbers in the bone marrow (BM) and particularly in the spleen where five to eight-fold rise was observed at the log phase of tumor growth. In addition, a remarkable increase in the number of megakaryocyte progenitors (CFU-MK and MK CFU-S) was observed both in the BM and spleen. Stimulation of these progenitors was more pronounced in the spleen than in the marrow, and the change was noticeable even from the third day of tumor bearing. Therefore, the results suggest that thrombocytosis associated with the growth of this experimental lymphoma was due to accelerated platelet production following stimulated megakaryocytopoiesis especially in the spleen.
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PMID:Stimulation of megakaryocytopoiesis and platelet production during growth of an experimental lymphoma. 1127 30

Eleven A-ring modified hexacyclic analogues of camptothecin (CPT) containing a 1,4-oxazine ring were synthesized from 10-hydroxycamptothecin (11a) and 7-ethyl-10-hydroxycamptothecin (3) (SN-38) in four to five steps and were subjected to the biological tests such as cytotoxicity, topoisomerase I (Topo I) inhibitory activity, acetylcholinesterase (AChE) inhibition, and stability in human plasma. Four compounds 15a, 15b, 16a, and 16c were about 2-fold more potent than topotecan and as potent as CPT toward human cancer cell lines A549, H128, WiDr, MKN45, SK-OV-3, and SK-BR-3 in vitro, even though the most active compound 15b was slightly less potent than SN-38. The potency of Topo I inhibition of these compounds showed relatively good correlation with their cytotoxicity. Most of the compounds exhibited AChE inhibitory activity weaker (9 +/- 2 to 20 +/- 3%) than CPT (23 +/- 5%) or topotecan (20 +/- 4%) and similar to SN-38 (13 +/- 2%), indicating that they might have little effect on causing early diarrhea. The stability of lactone forms of these compounds in human plasma seemed to be much higher than that of CPT and similar to that of topotecan but lower than that of SN-38. Among the new hexacyclic CPT analogues, compound 15b showed higher antitumor activity against human tumor xenograft, WiDr, in nude mice compared to that of SN-38. The most promising compound 15b has been selected for further development.
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PMID:Synthesis and biological evaluation of novel A-ring modified hexacyclic camptothecin analogues. 1133 69

Isolated glycosylphosphatidylinositol (GPI)-anchored proteins, when added to cells in vitro, incorporate into their surface membranes and, once incorporated, exert their native functions. Virtually any protein of interest, if expressed as a GPI-reanchored derivative, can be modified to acquire this capacity. Such transfer of proteins directly to cells, termed "protein engineering" or "painting" constitutes an alternative to conventional gene transfer for manipulating cell surface composition that has many potential applications. Previous studies with incorporated GPI-anchored proteins have focused almost entirely on their extracellular functions. In this study, biotinylated human erythrocyte (E(hu)) decay accelerating factor, E(hu) acetylcholinesterase, and GPI-reanchored murine B7-1 and B7-2 were used as GPI-anchored reporters to characterize their plasma membrane organization and cell signalling properties following addition to Hela or Chinese hamster ovary cells. For each reporter, three types of cell-association were documented; (1) nonphysiological attachment and/or incomplete insertion, (2) uncomplexed membrane integration, and (3) organization into TX-100-resistant microdomains. Transit from the first two compartments into the third, i.e., microdomains, progressed slowly, continuing even after 24 to 36 h and was associated with the acquisition of cell signalling capacity. All four reporters, incorporated in two different detergents, behaved similarly. When organized in microdomains, caveolin and other GPI proteins co-isolated with the incorporated reporter. These results have implications for protein engineering of cells in general, and in particular, for cells such as modified tumor cell immunogens administered to patients for therapeutic purposes.
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PMID:Properties of exogenously added GPI-anchored proteins following their incorporation into cells. 1152 49


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