Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have analysed the radiation response of a human medullary thyroid carcinoma cell line (MTT), characterized by the absence of a functional p53 protein, and the consequences of MDM2 overexpression in this process. We show that the product of the mdm2 proto-oncogene is able to sensitize MTT cells to ionizing radiation. After radiation treatment, MTT cells display histograms consistent with a G2M arrest. MTT cells expressing MDM2 (MTT-mdm2) are unable to respond to DNA damage with G2M arrest, and display a high percentage of apoptosis. MTT-mdm2 cells show high levels of E2F-1 protein, suggesting that the induction of apoptosis observed upon MDM2 overexpression could be dependent on E2F-1. This observation is further supported with assays showing that E2F-1 binding to specific DNA sequences is enhanced in MTT-mdm2 cells. Likewise, transactivation of reporter constructs exclusively dependent on E2F-1 is also elevated after transfection with MDM2. This effect can be reverted by transient transfection with p19ARF. To link the expression of E2F-1 with the induction of apoptosis, we generated clonal cell lines overexpressing E2F-1. Transfection with E2F-1 results in a low number of outgrowing colonies with reduced proliferation rates, indicating that E2F-1 is deleterious for cell growth. This negative regulation correlates with an increase in the percentage of the cell population with DNA content below 2N, suggesting that E2F-1 promotes apoptosis. Finally, overexpression of E2F-1 sensitizes MTT cells to radiation exposure. We conclude that the effects observed by MDM2 overexpression could be mediated by E2F-1.
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PMID:The mdm2 proto-oncogene sensitizes human medullary thyroid carcinoma cells to ionizing radiation. 1194 21

Glucocorticoids are integral to successful treatment of childhood acute lymphoblastic leukemia (ALL) and other lymphoid malignancies. A large body of data indicates that in various model systems, elevation of cyclic adenosine monophosphate (cAMP) can potentiate glucocorticoid response, although this has not been well evaluated as a potential leukemia treatment. Although cAMP analogs have been studied, little data exist regarding the potential toxicity to leukemia cells of pharmacologic elevation of cAMP levels in leukemic blasts. Using MTT assays of cell proliferation on CEM ALL cells, we found that aminophylline and other nonspecific phosphodiesterase (PDE) inhibitors suppress cell growth. This effect is replicated by the PDE4-specific PDE inhibitor rolipram, but not by specific inhibitors of the PDE1 or PDE3 classes. We found that PDE inhibitors cause increased dexamethasone sensitivity and a synergistic effect with the adenylyl cyclase activator forskolin. We observed several important cellular characteristics associated with this treatment, including elevation of cAMP, induction of p53 and p21(WAF1/CIP1) proteins, G(1) and G(2)/M cell cycle arrest, and increased apoptosis. Sensitivity to forskolin and rolipram is shared by at least 2 pediatric ALL cell lines, CEM and Reh cells. Some cell lines derived from adult-type lymphoid malignancies also show sensitivity to this treatment. These findings suggest that PDE inhibitors have therapeutic potential in human ALL and characterize the molecular mechanisms that may be involved in this response.
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PMID:Inhibition of PDE4 phosphodiesterase activity induces growth suppression, apoptosis, glucocorticoid sensitivity, p53, and p21(WAF1/CIP1) proteins in human acute lymphoblastic leukemia cells. 1196 8

This paper describes the first synthesis of phosmidosine and phosmidosine B, i.e., nucleotide antibiotics composed of 8-oxoadenosine and L-proline which are connected via a unique N-acyl phosphoramidate linkage. Phosmidosine has a yet-undetermined chiral center at the phosphorus atom of the N-acyl phosphoramidate linkage. Phosmidosine B is a demethylated phosmidosine derivative with no chirality on the phosphorus. Phosmidosine B was successfully synthesized by the reaction of an N-acetyl-8-oxoadenosine 5'-O-phosphoramidite derivative with an N-protected prolinamide in the presence of 5-(3,5-dinitrophenyl)-1H-tetrazole. The successful synthesis of phosmidosine was achieved by use of a tert-butoxycarbonyl (Boc) group, which was found to be selectively introduced into the 7-NH function of 8-oxoadenosine and to serve as a pseudo-protecting group due to its steric effect in such manner that the unmasked 6-amino group was not phosphitylated. Final coupling reaction of the 8-oxoadenosine 5'-phosphoramidite derivative with N-tritylprolinamide followed by full deprotection gave a mixture of phosmidosine and its diastereoisomer. The (13)C NMR spectra of the diastereomers suggest that the slow-eluted diastereomer 1b is the naturally occurring phosmidosine. The growth inhibitory activity of phosmidosine 1b, its diastereomer 1a, and phosmidosine B in various tumor cell lines was evaluated by the MTT assay. As the result, phosmidosine B showed high anticancer activities and both the diastereomers 1a and 1b of phosmidosine isolated were found to have similar but approximately 10 times higher anticancer activities than phosmidosine B. Moreover, it turned out that these phosmidosine derivatives showed characteristic inhibitory activities against cancer cells independent of their p53 phenotypes. These results suggest that phosmidosine and its related compounds would be promising as a new type of anticancer agents having a wide range of inhibitory activities against tumor cells.
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PMID:First synthesis and anticancer activity of phosmidosine and its related compounds. 1200 38

We investigated supra-additive cytotoxic effects of 5-fluorouracil (5FU) on gastric and colon cancer cells with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in vitro. p53 wild- and mutant-type gastric and colon cancer cell lines were treated by 5FU alone, TRAIL alone, and a combination of 5FU and TRAIL, and cell viability after each treatment was determined by MTT assay. The p53 wild-type cells were more sensitive to 5FU alone or to TRAIL alone than p53 mutant-type cells. The cell growth inhibitory effects of the combined treatment were supra-additive and more significant in proportion to the increasing concentrations of TRAIL as compared with 5FU alone both in p53 wild- and mutant-type cells. Furthermore, TRAIL could cause a decrease in 5FU IC(50) to within the range of clinically relevant doses, particularly in p53 wild-type cells. This is the first demonstration of the supra-additive antitumor activity of 5FU with TRAIL on gastric cancer cells, giving evidence that TRAIL can reduce the requirement for 5FU that ultimately results in minimizing risks for systemic side effects while increasing the antitumor activity of 5FU, suggesting the clinical applicability of this combination for gastric and colon cancers.
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PMID:Supra-additive antitumor activity of 5FU with tumor necrosis factor-related apoptosis-inducing ligand on gastric and colon cancers in vitro. 1216 12

Induction of apoptosis is an attractive strategy in cancer therapy but it clinical practice is not yet sufficient in choriocarcinoma. The quinolinone derivative, vesnarinone, is a novel inotropic agent used for treating congestive heart failure and may also have a potential anticancer activity. It induces apoptosis and differentiation in some tumor cell lines. We examined the antitumor effect of vesnarinone in eight cell lines established from human choriocarcinoma and hydatidiform mole using MTT assay and also analyzed the nuclear fragmentation of tumor cells by DNA electrophoresis assay. Vesnarinone inhibited the proliferation of choriocarcinoma cell lines in a dose-dependent manner and induced DNA fragmentation in cells. However, the BM cell line prepared by subcultivation from hydatidiform mole showed no growth suppression or DNA fragmentation in response to vesnarinone. On the other hand, PCR-SSCP analysis and direct DNA sequencing have shown that a human choriocarcinoma cell line, SCH, has a mutant p53 gene at codon 249. When SCH cells were treated with vesnarinone cellular proliferation was significantly inhibited. Vesnarinone suppressed the proliferation of all choriocarcinoma cell lines and induced apoptosis, regardless of the existence of p53 mutation. In addition, it has been found by RT-PCR that expression of c-Myc mRNA is upregulated by treating choriocarcinoma cells with vesnarinone. The finding suggests that vesnarinone might induce expression of c-Myc gene in choriocarcinoma cells, the product of which may be associated with the inhibition of cell growth and induce apoptosis. These results suggest that vesnarinone is a useful reagent for the treatment of choriocarcinoma.
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PMID:Induction of apoptosis in human choriocarcinoma cell lines by treatment with 3,4-dihydro-6-[4-(3,4-dimethoxybenzoyl)-1-piperazinyl]-2(1H)-quinolinone (vesnarinone). 1237 38

DNA structure and expression of p53 gene in human hepatoma cell lines SMMC-7721, YY-8103 and a spontaneously transformed liver cell line L-02 were analysed using the following method: analysis of allelic losses on chromosome 17p, PCR/SSCP, Northern blot and immunoprecipitation. There was no point mutation found in the exons 4-9 of the p53 gene, and a low level of expression of p53 gene was detected in the three cell lines. These observations were in agreement to the reported results of the relevant experiment using the human hepatoma cell line QGY-7703. Sensitivities of these cell lines and other eight human hepatoma cell lines (QGY-7703, PLC/PRF/5, Tong/HCC, Huh-7, FOCUS, Hep3B, SK-Hep-1, HepG2) with known p53 backgrounds to parvovirus H-1 was assayed using MTT method. Abnormality in the structure and/or function was observed in all of the cell lines examined except HepG2. The cell line HepG2 with normal structure and function of the p53 gene was found to be the least sensitive to H-1 in comparison to all the cell lines which have defeated structure and/or function of the p53 gene. The present study serves as a preliminary evidence that enhancement of the sensitivity of human hepatoma cell lines to H-1 is correlated to the abnormality of the structure and/or function of the p53 gene.
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PMID:[p53 gene expression of human hepatoma cell lines and their sensitivities to parvovirus H-1]. 1254 91

Phyllanthus urinaria (P. urinaria), a widely used herb medicine, was tested for the anticancer effect in its water extract for the first time. The water extract of P. urinaria significantly decreased the number of Lewis lung carcinoma cells in a dose-and time-dependent manner as determined by MTT assay. However, the water extract of P. urinaria did not exert any cytotoxic effect on normal cells such as endothelial cells and liver cells. Result from flow cytometry revealed a dose-dependent increase of dead cells 24 hours after treating Lewis lung carcinoma cells with P. urinaria extract. The anticancer activity of P. urinaria extract was due to the apoptosis induced in Lewis lung carcinoma cells, which was demonstrated by DNA fragmentation analysis and increased caspase-3 activity. The apoptosis triggered by P. urinaria extract in Lewis lung carcinoma cells was associated with the down-regulation of Bcl-2 gene expression, but not with p53, p21 and Bax. Furthermore, the partial inhibition of P. urinaria-induced apoptosis in Lewis lung carcinoma cells by pretreatment with cyclosporin A, a mitochondria permeability transition pore inhibitor, suggesting that P. urinaria extract induced the apoptosis of Lewis lung carcinoma cells, at least in part, through a mitochondria-associated intrinsic pathway.
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PMID:Phyllanthus urinaria triggers the apoptosis and Bcl-2 down-regulation in Lewis lung carcinoma cells. 1255 92

In this study we investigated the induction of apoptotic cell death and its potential mechanisms in cultured cortical neurons in response to deltamethrin exposure. The cultured cortical neurons were treated at 7 days with deltamethrin at concentrations of 10, 100, and 1000 nM, respectively. MTT assay showed that higher concentrations of deltamethrin (100 and 1000 nM) decreased neuronal viability in a time- and dose-dependent way. TUNEL staining revealed that numerous apoptotic cells appeared in the treated cultures compared to controls at 24, 48, and 72 h after treatment of 100 nM deltamethrin. Western blot analysis demonstrated that p53 and Bax expression were dramatically increased at the same time points, whereas Bcl-2 expression was significantly reduced at all time points after deltamethrin treatment. Further, we found that nitric oxide synthase inhibitor N(G)-nitro-L-arginine prevented deltamethrin-induced neuronal apoptosis and altered expression of p53, Bax, and Bcl-2. These results suggest that nitric oxide synthase might mediate deltamethrin-elicited neuronal apoptosis through modulating the expression of apoptosis-related genes.
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PMID:Deltamethrin induces apoptotic cell death in cultured cerebral cortical neurons. 1262 84

We investigated the anti-proliferative effects of luteolin and apigenin, isolated from Ixeris sonchifolia Hance, on HepG2 human hepatocellular carcinoma cells. In MTT assay luteolin showed more efficient anti-proliferative effects on cells than apigenin did. According to propidium iodide staining and flow cytometry studies, we postulated that these effects might be a result of cell cyde arrest. Hence we examined the changes of protein expressions related to cell cycle arrest. Western blotting data demonstrated that the down-regulated expression of CDK4 was correlated to the increase of p53 and CDK inhibitor p21(WAF1/CIP1) protein. These data suggest that luteolin may have potential as an anti-cancer agent.
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PMID:Inhibitory effects of luteolin isolated from Ixeris sonchifolia Hance on the proliferation of HepG2 human hepatocellular carcinoma cells. 1264 93

To evaluate the effects of wild-type p53 gene on the growth and chemotherapeutic sensitivity of human glioma cells, plasmid PC53-SN3 carrying wild-type p53 gene was transfected into U251 cells. p53 gene expression in transfected cells was detected by RT-PCR, the cell growth inhibition and apoptosis in either the absence or the presence of cisplatin was assessed by MTT and flow cytometry. The transfection of p53 gene into U251 cells was confirmed by RT-PCR. MTT showed that p53 gene by itself induced strong inhibition effect on the growth of U251 cells [inhibition rate, IR (79.60 +/- 5.69)%]. The killing effects of cisplatin by itself on U251 cells was not strong [IR (19.40 +/- 6.69)%, (24.41 +/- 2.68)%, (51.84 +/- 13.38)%, (66.22 +/- 5.02)%] and increased with the increase of cisplatin concentration (1, 2, 4, 8 micrograms/ml). When combined treatment of wild-type p53 gene transfection and cisplatin was used, that was significantly increased [IR (91.64 +/- 1.00)%, (94.98 +/- 1.67)%, (95.32 +/- 2.01)%, (95.65 +/- 1.00)%]. The apoptosis rate of U251 cells induced by p53 gene transfection was 17.38%. That induced by cisplatin increased (5.71%, 5.93%, 6.27%, and 6.81%) with the increase of cisplatin concentration (1, 2, 4, 8 micrograms/ml). The apoptosis rate was also significantly increased (23.50%, 23.54%, 23.89%, and 28.88%) after combined treatment of p53 and cisplatin with different concentration (1, 2, 4, 8 micrograms/ml). It is concluded that wild-type p53 gene and cisplatin could result in synergistic inhibition effects on the growth of human glioma cells.
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PMID:The effects of wild-type p53 gene transfection on the growth and chemotherapeutic sensitivity of human glioma cells. 1265 81


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