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)

Antineoplaston A10 (3-phenylacetylamino-2,6-piperidinedion) is a naturally occurring substance and was the first antineoplaston in the human body to be chemically identified. The effect of antineoplaston A10 on human hepatocellular carcinoma cell lines HepG2 and HLE has been examined. Antineoplaston A10 displayed anti-proliferative action inhibiting cell growth in a dose- and time-dependent manner in vitro as measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and clonogenic assays. Incubation with antineoplaston A10 for 48 h induced apoptotic events such as a typical apoptotic morphology, formation of a characteristic ladder pattern of DNA migration and accumulation of sub-G1 phase cells. Next, hepatoma xenografts in nude mice were employed to study the antitumor effects of antineoplaston A10 in vivo. Oral administration of antineoplaston A10 delayed the growth of HepG2 and HLE cells in the mice without a reduction in body weight. A higher proportion of apoptotic cells in xenografts was observed by means of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining. In addition, the level of expression of apoptotic marker p53 increased while that of anti-apoptotic protein bcl-2 decreased, as evaluated with immunohistochemical staining in the xenografts. These results suggested that antineoplaston A10 may inhibit the growth of human hepatoma cells through the induction of apoptosis.
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PMID:Induction of apoptosis in human hepatocellular carcinoma cells by synthetic antineoplaston A10. 1769 34

A ubiquitin protein ligase (E3), E3(Histone)/LASU1 (Mule/ARF-BP1/HUWE1), was recently identified that mediates ubiquitination of core histones, the Mcl-1 anti-apoptotic protein, and the p53 tumor suppressor protein. However, the expression of E3(Histone)/LASU1 remains poorly studied. Because we identified E3(Histone)/LASU1 from the testis, we explored its regulation during spermatogenesis. In the first wave of rat spermatogenesis, E3(Histone)/LASU1 mRNA and protein had peak expression at days 10 and 20, respectively, and decreased with age. Consistent with these findings, immunohistochemistry revealed that E3(Histone)/LASU1 was highly expressed in nuclei from spermatogonia to mid-pachytene spermatocytes. There was no obvious staining in spermatids, when histones are ubiquitinated and degraded. E3(Histone)/LASU1 was also expressed in other tissues. However, except in neuronal cells of the brain, expression was cytoplasmic. Thus, E3(Histone)/LASU1 may play a role in chromatin modification in early germ cells of the testis, but also has functions in other tissues.
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PMID:Regulated expression of the ubiquitin protein ligase, E3(Histone)/LASU1/Mule/ARF-BP1/HUWE1, during spermatogenesis. 1782 42

UV irradiation triggers apoptosis through both the membrane death receptor and the intrinsic apoptotic signaling pathways. Bax, a member of the Bcl-2 family of proteins, translocates from the cytosol to the mitochondrial membrane during UV-induced apoptosis, but the regulation of Bax translocation by UV irradiation remains elusive. In this study, we show that Bax translocation, caspase-3 activation and cell death by UV irradiation are not affected by Z-IETD-fmk (caspase-8 inhibitor), but delayed by Pifithrin-alpha (p53 inhibitor), although Bid cleavage could be completely abolished by Z-IETD-fmk. Co-transfecting YFP-Bax and Bid-CFP into human lung adenocarcinoma cells, we demonstrate that translocation of YFP-Bax precedes that of Bid-CFP, there is no significant FRET (fluorescence resonance energy transfer) between them. Similar results are obtained in COS-7 cells expressing YFP-Bax and Bid-CFP. Furthermore, using acceptor photobleaching technique, we observe that there is no interaction between YFP-Bax and Bid-CFP in both healthy and apoptotic cells. Additionally, during UV-induced apoptosis there is downregulation of Bcl-x(L), an anti-apoptotic protein. Overexpression of Bcl-x(L) in cells susceptible to UV-induced apoptosis prevents Bax translocation and cell death, repression of Bid protein with siRNA (small interfering RNA) do not inhibit cell death by UV irradiation. Taken together, these data strongly suggest that Bax translocation by UV irradiation is a Bid-independent event and inhibited by overexpression of Bcl-x(L).
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PMID:Bid is not required for Bax translocation during UV-induced apoptosis. 1785 51

Triptolide, derived from the traditional Chinese herb, Tripterygium wilfordii, sensitizes cancer cells to apoptosis. Glioblastoma multiforme (GBM), which accounts for most cases of central nervous malignancy, has a very poor prognosis and lacks effective therapeutic inventions. We, therefore, investigated the effects of different concentrations of, and different periods of exposure to, triptolide on cell proliferation and apoptosis in the glioma cell lines, U251MG and U87MG, and in normal human fetal astrocytes. Cell proliferation was investigated by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) assay and growth curve analysis, and apoptosis was assessed from genomic DNA fragmentation. Triptolide showed dose-dependent inhibition of cell proliferation and induction of apoptosis in glioma cells. It also increased the ratio of the pro-apoptotic protein, Bax, to the anti-apoptotic protein, Bcl-2. Since U87MG has the wild-type p53 gene whereas U251MG harbours a mutated p53 gene, our results indicate that triptolide induces apoptosis in GBM cells via a p53-independent pathway. The dose-dependent inhibition of cell proliferation and induction of apoptosis by triptolide may involve upregulation of Bax and downregulation of Bcl-2.
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PMID:The effect of triptolide on apoptosis of glioblastoma multiforme (GBM) cells. 1790 Apr 3

TIP30 (Tat-interacting protein 30), a newly found proapoptotic factor, appears to be involved in multiple functions including metabolic suppression, apoptosis induction, and diminishing angiogenic properties. In the present study, we reported that mitochondrial events were required for apoptosis induced by TIP30 in hepatocellular carcinoma cells (HCC cells). Translocation of Bax was essential for TIP30-induced apoptosis, whereas overexpression of the anti-apoptotic protein Bcl-xL delayed both second mitochondria-derived activator of caspases (Smac/DIABLO) release and onset of apoptosis. Furthermore, TIP30-induced apoptosis was dependent on caspase activity because the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp (OMe)-fluoromethyl ketone (z-VAD-fmk) blocked DNA fragmentation. Release of Smac/DIABLO from the mitochondria through the TIP30-P53-Bax cascade was required to remove the inhibitory effect of XIAP (X-linked Inhibitor of Apoptosis) and allowed apoptosis to proceed. Our results showed for the first time that Bax-dependent release of Smac/DIABLO, cytochrome c and AIF from the mitochondria mediated the contribution of the mitochondrial pathway to TIP30-mediated apoptosis. Our data suggested that adenovirus-mediated overexpression of TIP30 was capable of inducing therapeutic programmed cell death in vitro by activating the mitochondrial pathway of apoptosis. On the basis of these studies, elucidating the mechanism by which TIP30 induces cell death might establish it as an anticancer approach.
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PMID:Tip30-induced apoptosis requires translocation of Bax and involves mitochondrial release of cytochrome c and Smac/DIABLO in hepatocellular carcinoma cells. 1799 90

Senescent cells are known to be resistant to apoptosis induced by genotoxic stress. Here we examine apoptosis in human diploid fibroblasts that are old but not yet senescent. We found that as cells aged, they became progressively more resistant to UV-induced apoptosis with an eventual apoptosis reduction of 10-20-fold. This behavior tracked a progressive disruption of the normal balance between pro- and anti-apoptotic proteins. In young cells, the level of anti-apoptotic protein BCL-xL quickly fell after UV irradiation while pro-apoptotic protein BAX rose. The increase in BAX tracked the level of P53, a transcriptional regulator of BAX. In older cells, the scenario was quite different. Instead of decreasing, the level of BCL-xL increased dramatically after UV stress so that the ratio of pro-apoptotic BAX to anti-apoptotic BCL-xL remained low. RNAi against BCL-xL restored the UV-sensitivity of old cells, indicating that BCL-xL is itself responsible for the pre-senescence decline in the ability of a genotoxic stress to induce apoptosis.
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PMID:Progressive apoptosis resistance prior to senescence and control by the anti-apoptotic protein BCL-xL. 1826 22

In pediatric acute lymphoblastic leukemia (ALL), overexpression of murine double minute 2 (MDM2) protein by leukemic cells is typically associated with a wild-type (wt)-p53 phenotype and chemoresistance. A recently developed small-molecule antagonist of MDM2, nutlin-3, inhibits the MDM2-p53 interaction, resulting in induction of p53 activity and apoptosis. In this study, we evaluated the cytotoxic effect of nutlin-3 on ALL cells with different p53 status and MDM2 expression, using 18 cell lines and 30 primary leukemia samples. We found that both ALL cell lines and primary ALL samples with wt-p53 are sensitive to nutlin-3. No cytotoxic effect of nutlin-3 was detected in ALL cells with either p53-mutant or -null phenotype. In wt-p53 ALL cells, there was a significant positive correlation between MDM2 expression levels and sensitivity to nutlin-3. Nutlin-3-induced cell death was mediated by p53-induced activation of proapoptotic proteins and by p53-induced repression of the anti-apoptotic protein survivin. As p53 function is inhibited by MDM2 in chemoresistant, MDM2-overexpressing ALL cells, potent killing of these cells by nutlin-3 suggests that this agent may be a novel therapeutic for refractory ALL.
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PMID:MDM2 antagonist nutlin-3 is a potent inducer of apoptosis in pediatric acute lymphoblastic leukemia cells with wild-type p53 and overexpression of MDM2. 1827 46

Triptolide, a purified diterpenoid triepoxide compound derived from a traditional Chinese medicine, Tripterygium wilfordii HOOK. f (TWHf), has been used in the treatment of autoimmune and inflammatory diseases. However, the toxicity of triptolide limits its application to a great extent. In the present study, we treated human normal liver L-02 cells (L-02 cells) with triptolide in vitro and investigated its toxic effects. The cytotoxicity was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for cellular viability and by flow cytometry and Hoechst 33258 staining for apoptosis. The mitochondrial membrane potential (delta psi m) was evaluated by flow cytometry with JC-1 as probe. After treatment with triptolide, a decrease in the viability of L-02 cells and increase in apoptosis were observed. Triptolide-induced apoptosis was accompanied by loss of mitochondrial membrane potential and release of cytochrome c (cyt-c) from the mitochondria to the cytosol and down-regulation of anti-apoptotic protein Bcl-2 levels with concurrent up-regulation in pro-apoptotic protein Bax levels and tumor suppressor protein p53 levels. Triptolide-increased activity of caspase 9 and caspase 3 was also observed. These results indicate that triptolide induced cytotoxicity in L-02 cells by apoptosis, which is mediated through mitochondrial pathway.
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PMID:Involvement of mitochondrial pathway in triptolide-induced cytotoxicity in human normal liver L-02 cells. 1837 47

To investigate the anti-proliferative and chemosensitizing effects of luteolin on human gastric cancer, gastric cancer AGS cells were treated with luteolin and/or other chemotherapeutic agents. Cell growth was assessed by MTT assay, cell cycle and apoptosis were assessed by flow-cytometric analysis, and the expression of major proteins regulating cell cycle and apoptosis was also detected. The results showed that luteolin inhibited the growth of gastric cancer cells in a dose- and time-dependent manner. Flow cytometry revealed that the percentage of cells at G2/M phase increased dose-dependently. The protein levels of Cdc2, Cyclin B1 and Cdc25C were reduced and p21/cip1 was up-regulated after the treatment with luteolin. Furthermore, luteolin induced apoptosis in gastric cancer AGS cells. Western blotting showed that luteolin treatment significantly increased the levels of pro-apoptotic proteins, including Caspase-3, 6, 9, Bax, and p53, and decreased the levels of anti-apoptotic protein Bcl-2, thus shifting the Bax/Bcl ratio in favor of apoptosis. It was also demonstrated that a combinational treatment of cisplatin and luteolin induced more effectively cell growth inhibition, compared to cisplatin treatment alone. These findings indicate the anti-proliferative and chemosensitizing effects of luteolin on human gastric cancer AGS cells and luteolin may be a promising candidate agent used in the treatment of gastric cancer.
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PMID:Anti-proliferative and chemosensitizing effects of luteolin on human gastric cancer AGS cell line. 1839 71

Autophagy is a cellular process of bulk degradation of damaged organelles, protein aggregates and other macromolecules in the cytoplasm. It is thought to be a general response to stress contributing to cell death; alternatively it might act as a cytoprotective mechanism. Here we found that administration of cisplatin induced the formation of autophagic vesicles and autophagosomes in mouse kidneys. In cultured proximal tubular cells, the nephrotoxin caused autophagy in a dose- and time-dependent manner prior to apoptosis. Notably, autophagy occurred within hours of cisplatin administration but this was partially suppressed by the p53 inhibitor pifithrin-alpha, suggesting that p53 is involved in autophagic signaling. This cisplatin-induced autophagy was attenuated in renal cells stably transfected with Bcl-2, suggesting an anti-autophagic role for this well-known anti-apoptotic protein. Blockade of autophagy with pharmacological inhibitors (3-methyladenine or bafilomycin) or shRNA knockdown of the autophagic gene Beclin increased tubular cell apoptosis during cisplatin treatment. Our study has found that autophagy occurs in acute kidney injury and this may be an important protective mechanism for cell survival.
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PMID:Autophagy is cytoprotective during cisplatin injury of renal proximal tubular cells. 1909 18


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