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)

Establishing mammalian germ-cell lines capable of differentiation in vitro would greatly facilitate the study of gametogenesis and the meiotic process that is so fundamental for reproduction and the maintenance of genetic diversity of the species. We have established two germ-cell lines [GC-2spd(ts) and GC-3spc(ts)] by cotransfecting primary mouse testicular germ cells with the simian virus 40 large tumor antigen gene and the gene coding for a temperature-sensitive mutant of p53. Both cell lines express the germ cell-specific lactate dehydrogenase C4 isozyme and cytochrome ct isoform. At the permissive temperature of 37 degrees C, the GC-2spd(ts) line generates cells with a haploid DNA content and morphologic and biochemical features of round spermatids, including the appearance of an acrosomic granule. The identification of a flagellar axoneme when these cells are cultured at 32 degrees C further indicates that these cells correspond to the early spermatid stages of spermiogenesis.
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PMID:Immortalized germ cells undergo meiosis in vitro. 820 22

Nitric oxide (NO)-releasing compounds cause apoptotic cell death in RAW 264.7 macrophages. This is confirmed morphologically by chromatin condensation and biochemically by DNA laddering. With use of spontaneously decomposing NO donors known as NONOates we show that the integral of concentration over time accounts for the NO-donor damaging ability. A 30-min exposure to the rapidly decomposing NO-donor diethylamine-nitric oxide complex (DEA-NO) causes irreversible damage and apoptotic cell death after 6 to 8 h. For intermediate NO releasers like sodium nitroprusside, S-nitrosoglutathione (GSNO), and spermine-NO removal of the NO-donating compound halts fragmentation to a certain degree. The relatively stable diethylenetriamine-nitric oxide complex initiates fragmentation only after prolonged exposure. NO-mediated apoptotic signaling in macrophages neither decreases cellular NAD+, nor causes a drop in APT. Consistently, membrane integrity measured by lactate dehydrogenase release is preserved and inhibitors of poly(ADPribose) polymerase, like 3-aminobenzamide, are noneffective. The level of the tumor suppressor p53 increases in response to NO donors like GSNO and effectively senses NO intoxication in macrophages. GSNO removal concomitantly allows p53 to decline with only a small percentage of cells showing DNA fragmentation. Contrary, massive damage initiated by a 1-h exposure to DEA-NO is irreversible, with persistent p53 levels. NO-mediated apoptotic cell death in RAW 264.7 macrophages correlates with the degree of p53 accumulation, probably sensing the integrity of the genome.
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PMID:Nitric oxide (NO) in apoptotic versus necrotic RAW 264.7 macrophage cell death: the role of NO-donor exposure, NAD+ content, and p53 accumulation. 861 78

Alterations in the p53 tumor-suppressor gene occur in 35-60% of human glioblastomas, and re-introduction of p53 can suppress neoplastic growth. To evaluate the potential for p53 gene therapy of glioblastoma, we have analyzed the response of human glioblastoma cell lines in vitro and in vivo to experimental therapy with replication-deficient recombinant adenoviruses encoding wild-type p53 (rAd-p53). Western blot analyses showed high-level expression of p53 protein after treatment with rAd-p53, and transgene expression was dependent on promoter strength. A p53-specific dose-dependent inhibition of in vitro cellular proliferation was observed in 5 of 6 cell lines, and growth inhibition corresponded to adenovirus-mediated gene transfer and expression. p53-specific cell death was quantitated by release of the lactate dehydrogenase enzyme. Fragmentation of DNA into nucleosomal oligomers and the occurrence of a hypodiploid cell population detected by flow cytometry provided evidence for apoptosis. Studies in nude mice demonstrated that ex vivo infection with rAd-p53 suppressed the tumorigenic potential of human glioblastoma cells. Furthermore, direct injection of rAd-p53 into established s.c. xenografts inhibited tumor growth. Our observations suggest that re-introduction of wild-type p53 may have potential clinical utility for gene therapy of glioblastoma.
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PMID:Adenovirus-mediated p53 gene transfer suppresses growth of human glioblastoma cells in vitro and in vivo. 882 52

1. The effects of quercetin on drug metabolising enzymes and oxygen radicals were studied in human HepG2 cells. 2. Cytotoxicity of quercetin in HepG2 cells was seen at 50 microM and above as evaluated by lactate dehydrogenase (LDH) leakage, neutral red (NR) uptake, and 3-(4,5-dimethyl-thiazol-2yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction. 3. Quercetin inhibited activity of human cytochrome P-450 towards ethoxycoumarin and ethylresorufin at relatively low substrate concentrations (0.1 microM and above). 4. In comparison to induction by the positive control (beta-naphthoflavone; 1.0 microM), quercetin did not significantly induce the metabolism of ethoxycoumarin or glutathione-S-transferase (GST) protein or activity. 5. Response elements for human CYP1A1, GST lambda a, xenobiotic response element (XRE), fos, HSP70, CRE, p53, NF kappa B and DNA damage (GADD) in HepG2 cells were not activated by quercetin. 6. Quercetin exhibited antioxidant activity in HepG2 cells as evidenced by its ability to inhibit the oxidation of the fluorochrome dichlorofluorescin. 7. The results indicate a range of potential beneficial effects of quercetin with respect to the influence on carcinogen-metabolising enzymes, scavenging of reactive oxygen species and a lack of stress response in HepG2 cells.
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PMID:Effects of quercetin on drug metabolizing enzymes and oxidation of 2',7-dichlorofluorescin in HepG2 cells. 942 83

Mesangial cells undergo cell death both by apoptosis and necrosis during glomerular disease. Since nucleotides are released from injured and destroyed cells in the glomerulus, we examined whether extracellular ATP and its receptors may regulate cell death of cultured mesangial cells. Addition of extracellular ATP (300 microM to 5 mM) to cultured rat mesangial cells for 90 min caused a 5. 8-fold increase in DNA fragmentation (terminal deoxynucleotidyl transferase assay) and a 4.2-fold increase in protein levels of the tumor suppressor p53, which is thought to regulate apoptosis. Apoptotic DNA fragmentation was confirmed by the diphenylamine assay and by staining with the DNA-specific fluorochrome Hoechst 33258. The necrotic markers, release of lactate dehydrogenase and uptake of trypan blue, were not positive before 3 h of ATP addition. The effects of ATP on DNA fragmentation and p53 expression were reproduced by the purinergic P2Z/P2X7 receptor agonist, 3'-O-(4-benzoylbenzoyl)-ATP, and inhibited by the P2Z/P2X7 receptor blocker, oxidized ATP. Transcripts encoding the P2Z/P2X7 receptor were expressed by cultured mesangial cells as determined by Northern blot analysis. P2Z/P2X7 receptor-associated pore formation in the plasma membrane was demonstrated by the Lucifer yellow assay. We conclude that activation of P2Z/P2X7 receptors by extracellular ATP causes apoptosis and necrosis of cultured mesangial cells. Activation of purinergic P2Z/P2X7 receptors may play a role in causing death of mesangial cells during glomerular disease.
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PMID:Extracellular ATP causes apoptosis and necrosis of cultured mesangial cells via P2Z/P2X7 receptors. 984 14

A clinicopathologic study was conducted to assess the implication of HTLV-I infection, Strongyloides stercoralis (Ss) infection, and P53 overexpression in the development, response to treatment, and evolution of non-Hodgkin's lymphoma (NHL) in Martinique, French West Indies. Two groups of patients, with 22 and 41 participants with B-cell and T-cell lymphoma, respectively, were analyzed. HTLV-I antibodies were detected in 24 (59%) patients with T-cell lymphoma of whom 19 (46%) fulfilled diagnostic criteria of adult T-cell leukemia/lymphoma (ATLL). By comparison with other T-cell lymphomas, patients with ATLL were significantly younger (52 versus 63 years; p = .03), had a significantly higher incidence of hypercalcemia (60% versus 0%; p = .0001), a trend for higher incidence of digestive tract localization (21% versus 4%; p = .1) and significantly shorter median survival (6 versus 17 months; p = .03). Similar results were observed when all 24 HTLV-I-infected patients with T-cell lymphoma were compared with the 17 seronegative patients. Strongyloidiasis was diagnosed in 11 of 34 patients tested for Ss infection. All 4 Ss-infected (Ss-positive) ATLL patients treated with combination chemotherapy achieved complete remission (CR) versus only 2 of 7 Ss-negative ATLL patients (p = .04). In addition, survival of Ss-positive patients with ATLL was better than that of the uninfected patients: 27 versus 5 months, p = .04, respectively). P53 expression was assessed by immunohistochemistry on lymph node biopsies from 37 patients including 18 B-cell lymphomas, 14 ATLL, and 5 other T-cell lymphomas. P53 overexpression (P53-positive) was observed in 6 samples that corresponded in all 6 patients with ATLL. All P53-positive ATLL patients had stage IV disease with elevated lactate dehydrogenase (LDH) levels. By comparison with other ATLL patients studied for p53 expression, P53-positive ATLL were characterized by a lower response rate to combination chemotherapy (CR: 0 of 6 versus 4 of 6; p = .04) and a shorter survival (2 versus 9 months, p = .04). Our results suggest that ATLL represents almost 50% of T-cell lymphomas in Martinique; Ss infection during ATLL seems to be linked with a high response rate to chemotherapy and prolonged survival; and P53 overexpression is observed in almost 50% of aggressive ATLL from Martinique and, even in advanced clinical subtypes, is associated with resistance to chemotherapy and short-term survival.
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PMID:Implication of HTLV-I infection, strongyloidiasis, and P53 overexpression in the development, response to treatment, and evolution of non-Hodgkin's lymphomas in an endemic area (Martinique, French West Indies). 1009 85

The cytotoxic effect of high-linear-energy transfer (LET) carbon beams on two human glioblastoma cell lines (A172 and TK1) was analyzed, especially concerning cell death, including apoptosis. Gamma-ray radiation was used for comparison. The results of standard colony formation assay showed that the survival fraction of each cell line decreased in an LET-dependent manner. The results of other direct cytotoxic assays, dye exclusion test, and lactate dehydrogenase (LDH) release assay, also displayed a similar relationship between the cytotoxic effect of carbon beams and LET. The maximum values of the cell death index (CDI) were 50.2% in A172 and 37.5% in TK1, both obtained on day 7 after exposure to carbon beams of 80 keV/microm. Apoptosis was observed only on days 4 and 7 after carbon beam irradiation, with maximum values of 7% in A172 and 4.5% in TK1, and the induction of apoptosis after high-LET radiation could be p53-independent. This indicated that a combination of multiple assays to detect cell death was important in evaluating the radiosensitivity of tumor cells, because this approach could more precisely reflect the clinical effectiveness of radiotherapy.
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PMID:Cell death induced by high-linear-energy transfer carbon beams in human glioblastoma cell lines. 1032 42

Nitroxyl anion (NO(-)), the one-electron reduction product of nitric oxide (NO(.)), is formed under various physiological conditions. We have used four different assays (DNA strand breakage, 8-oxo-deoxyguanosine formation in calf thymus DNA, malondialdehyde generation from 2'-deoxyribose, and analysis of site-specific DNA damage using (32)P-5'-end-labeled DNA fragments of the human p53 tumor suppressor gene and the c-Ha-ras-1 protooncogene) to study the effects of NO(-) generated from Angeli's salt on DNA damage. It was found that strong oxidants are generated from NO(-), especially in the presence of H(2)O(2) plus Fe(III)-EDTA or Cu(II). NO(.) released from diethylamine-NONOate had no such effect. Distinct effects of hydroxyl radical (HO(.)) scavengers and patterns of site-specific DNA cleavage caused by Angeli's salt alone or by Angeli's salt, H(2)O(2) plus metal ion suggest that NO(-) acts as a reductant to catalyze the formation of the HO(.) from H(2)O(2) plus Fe(III) and formation of Cu(I)-peroxide complexes with a reactivity similar to HO(.) from H(2)O(2) and Cu(II). Angeli's salt and H(2)O(2) exerted synergistically cytotoxic effects to MCF-7 cells, determined by lactate dehydrogenase release assay. Thus NO(-) may play an important role in the etiology of various pathophysiological conditions such as inflammation and neurodegenerative diseases, especially when H(2)O(2) and transition metallic ions are present.
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PMID:Cytotoxicity and site-specific DNA damage induced by nitroxyl anion (NO(-)) in the presence of hydrogen peroxide. Implications for various pathophysiological conditions. 1040 35

The new human hepatocyte cell line HepZ was investigated with regard to use it for a mass cell cultivation. The cells were originally derived from a human liver biopsy and immortalized through lipofectamine-mediated transfection of albumin-promotor-regulated antisense constructions against the negative controlling cell cycle proteins Rb and p53 (pAlb asRb, pAIb asp53). Furthermore, plasmids including genes coding for the cellular transcription factor E2F and D1 cyclin (pCMV E2F, pSV2neo D1) were cotransfected to overcome the G1-restriction point. Cell cultivation was performed in a 2-liter bioreactor with a working volume of 1 liter. With CultiSpher G microcarriers used in a concentration of 3 g/l a maximal density of 7.1 x 10(6) cells/ml was achieved in a cultivation period of 20 days. The cells exhibited a maximal specific growth rate of 1.0 per day in the first 4 days. After 9 days of cultivation the stationary growth phase was reached with an average cell density of 5.5 x 10(6) cells/ml. The viability status of the culture was determined indirectly by measuring of the lactate dehydrogenase activity (LDH) at 37 degrees C. During the growth phase the activity rose slightly up to a value of 200 U/l. The cells were flat after first attachment on the gelatine microcarriers and spherical after growing into the three-dimensional inner matrix--both of which characteristics were verified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The liver-specific cytochrome P450 activity was challenged with a pulse of 7 micrograms/ml lidocaine at a cell density of 4.5 x 10(6) cells/ml. After an induction period of 3 days with 50 micrograms/ml of phenobarbital, 26 ng/ml MEGX were generated within one day compared to 5 ng/ml without induction. The new cell line HepZ has proven to retain liver-specific qualities and to be appropriate for mass cell cultivation for bioartificial devices.
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PMID:Cultivation and characterization of a new immortalized human hepatocyte cell line, HepZ, for use in an artificial liver support system. 1041 82

Oligodendrocytes (OLs) and their myelin membranes are the primary targets in the autoimmune disease multiple sclerosis (MS). The inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) has been implicated as a mediator of OL cell injury. TNF-alpha is detectable within MS lesions and induces apoptosis of mature human OLs in vitro. One possible mechanism by which TNF-alpha mediates cell death is through the activation of c-jun N-terminal kinase (JNK). We have previously shown that treatment of human OLs with TNF-alpha leads to activation of JNK. Here we provide evidence that p53, a regulator of the cell cycle and apoptosis, is a mediator of TNF-alpha-induced apoptosis of OLs. Although p53 was undetectable by western blot analysis in adult human OLs, its levels increased within 24 h after TNF-alpha treatment (100 ng/ml). The induced p53 was immunolocalized to the nucleus prior to the appearance of significant numbers of apoptotic cells. Overexpression of p53 by adenovirus-mediated gene transfer into human OLs in vitro resulted in marked apoptosis as revealed by in situ cleavage of DNA (TUNEL positive), decreased mitochondrial function, and release of lactate dehydrogenase into the culture medium. These in vitro studies demonstrate that increased p53 levels are associated with apoptosis of human OLs. The findings further implicate p53 as a target for the JNK pathway activated during TNF-alpha-mediated cell death of human adult OLs.
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PMID:p53 induction by tumor necrosis factor-alpha and involvement of p53 in cell death of human oligodendrocytes. 1042 56


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