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)

Stimulation of apoptosis by p53 is accompanied by induction of the BH-3-only proapoptotic member of the BCL-2 family, BIK, and ectopic expression of BIK in p53-null cells caused the release of cytochrome c from mitochondria and activation of caspases, dependent on a functional BH-3 domain. A significant fraction of BIK, which contains a predicted transmembrane segment at its COOH terminus, was found inserted in the endoplasmic reticulum (ER) membrane, with the bulk of the protein facing the cytosol. Restriction of BIK to this membrane by replacing its transmembrane segment with the ER-selective membrane anchor of cytochrome b(5) also retained the cytochrome c release and cell death-inducing activity of BIK. Whereas induction of cell death by BIK was strongly inhibited by the caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone, the inhibitor was without effect on the ability of BIK to stimulate egress of cytochrome c from mitochondria. This benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone-insensitive pathway for stimulating cytochrome c release from mitochondria by ER BIK was successfully reconstituted in vitro and identified the requirement for components present in the light membrane (ER) and cytosol as necessary for this activity. Collectively, the results identify BIK as an initiator of cytochrome c release from mitochondria operating from a location at the ER.
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PMID:BH-3-only BIK functions at the endoplasmic reticulum to stimulate cytochrome c release from mitochondria. 1188 14

The p16 tumor suppressor gene is frequently inactivated in human cancer tissues and cell lines. We previously reported that wild-type p16 expression from an adenovirus vector (Adv/p16) induced p53-dependent apoptotic cell death in non-small cell lung cancer (NSCLC) cell lines. Here we show the potential mechanism of apoptosis induced by Adv/p16 infection. Infection of human NSCLC cell line A549, which carries the wild-type p53 gene, with Adv/p16 resulted in activation of caspase-3, accompanied by the cleavage of its substrate poly (ADP-ribose) polymerase (PARP), on day 3 of infection. The retinoblastoma (Rb) cell cycle regulator protein was also cleaved after activation of caspase-3; when the levels of Rb significantly diminished, apoptosis began. When A549 cells were pretreated with the caspase-inhibitory peptide N-acetyl-asp-Glu-Val-Asp-CHO (aldehyde) (Ac-DEVD-CHO), Adv/p16-mediated apoptosis and Rb cleavage were greatly inhibited. Furthermore, MDM2, a negative regulator of p53 expression was upregulated 3 days after Adv/p16 infection, and MDM2 was subsequently cleaved by caspase-3; MDM2 cleavage was inhibited by Ac-DEVD-CHO treatment. These data implied that cleavage of Rb, in addition to activation of caspase-3, represented a mechanism by which Adv/p16 induced apoptotic cell death in human NSCLC cells. Our results support the clinical relevance of Adv/p16 as a treatment for p16-null human NSCLC that express wild-type p53.
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PMID:Activation of caspase-3 and cleavage of Rb are associated with p16-mediated apoptosis in human non-small cell lung cancer cells. 1196 Mar 84

We have previously reported that combretastatin-A4 prodrug (CA4P), anantitubulin/antiangiogenic agent isolated from the South African willow tree Combretum caffrum, induced cell death primarily through mitotic catastrophe in a panel of human B-lymphoid tumors. In this study, we investigated the molecular aspects of the mitotic catastrophe and whether or not it shares the same pathways of apoptosis. For this we studied the effect of CA4P on selected markers of apoptosis [caspases 9 and 3, poly(ADP-ribose) polymerase (PARP), bcl-2, and bax] and G2-M protein regulators (p53, MDM2, 14-3-3sigma, GADD45, cdc2, cdc25, chk1, wee1, p21, and cyclin B1). The chronic lymphocytic leukemia cell line WSU-CLL was used for this purpose. Western blot analysis showed that 24 h of CA4P (5 nM) exposure induces caspase 9 activation and PARP cleavage. However, the addition of Z-Val-Ala-Asp-fluoromethylketone (a general caspase inhibitor) or Z-Leu-Glu(OMe)-His-Asp(OMe)-CH2F (a caspase 9 inhibitor) before CA4P treatment did not block cell death. No change in bcl-2 or bax protein expression was observed. Exposure of WSU-CLL cells to 4 and 5 nM CA4P was associated with overproduction of total p53 and no dramatic change in MDM2, 14-3-3sigma, GADD45, the cyclin-dependent kinase cdc2, its inhibitory phosphorylation, the cdc2-inhibitory kinase (wee1), chk1, or cdc25 hyperphosphorylation. The overaccumulation of p21 and cyclin B1 protein was obvious at 24 h. Furthermore, CA4P treatment showed an increase in the expression of a marker of mitosis (mitotic protein monoclonal-2 antibody) and an overaccumulation of the cyclin B in the nucleus. Our findings suggest that CA4P induces mitotic catastrophe and arrest of WSU-CLL cells mostly in the M phase independent of p53 and independent of chk1 and cdc2 phosphorylation pathways. Apoptosis is a secondary mechanism of death in a small proportion of cells through activation of caspase 9 and PARP cleavage. The two mechanisms of cell death, i.e., mitotic catastrophe and apoptosis, are independent of each other in our model.
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PMID:Combretastatin-A4 prodrug induces mitotic catastrophe in chronic lymphocytic leukemia cell line independent of caspase activation and poly(ADP-ribose) polymerase cleavage. 1217 7

The role of Bax and Bak, 2 proapoptotic proteins of the Bcl-2 family, was analyzed in primary B-cell chronic lymphocytic leukemia (CLL) cells following in vitro treatment with fludarabine, dexamethasone, or the combination of fludarabine with cyclophosphamide and mitoxantrone (FCM). A strong correlation was found between the number of apoptotic cells and the percentage of cells stained with antibodies recognizing conformational changes of Bax (n = 33; r = 0.836; P <.001) or Bak (n = 10; r = 0.948; P <.001). Preincubation of CLL cells with Z-VAD.fmk (N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone), a broad caspase inhibitor, abolished caspase-3 activation, exposure of phosphatidylserine residues, and reactive oxygen species generation; partially reversed the loss of transmembrane mitochondrial potential (DeltaPsim); but did not affect Bax or Bak conformational changes. These results indicate that the conformational changes of Bax and Bak occur upstream of caspase activation or are caspase independent. Following drug-induced apoptosis, Bax integrates into mitochondria, as demonstrated by fluorescence microscopy and Western blot, without changes in the total amount of Bax or Bak protein. Fludarabine and FCM induce p53 stabilization, but do not seem to be essential in inducing Bax and Bak conformational changes, as they are also observed in dexamethasone-treated CLL cells. These results demonstrate that, in CLL cells, the change in the intracellular localization of Bax from cytosol to mitochondria and the conformational changes of Bax and Bak are among the early steps in the induction of cell death.
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PMID:Spontaneous and drug-induced apoptosis is mediated by conformational changes of Bax and Bak in B-cell chronic lymphocytic leukemia. 1217 4

To examine the p53-mediated biological activities and signalling pathways, we generated stable transfectants of the p53-null IW32 murine erythroleukemia cells expressing the temperature-sensitive p53 mutant DNA, tsp53(val135). Two clones with different levels of p53 protein expression were selected for further characterization. At permissive temperature, clone 1-5 cells differentiated along the erythroid pathway, and clone 3-2 cells that produced greater levels (3.5-fold) of p53 underwent apoptosis. Apoptosis of 3-2 cells was accompanied by mitochondrial cytochrome c release and caspase activation as well as by cleavage of caspase substrates. Bax protein was induced to a similar extent in these clones by wild-type p53; expression of p21(Cip1/Waf1) and p27(Kip1) proteins was also increased. However, significantly lesser extent of induction for both CDK inhibitors was detected in the apoptotic 3-2 clone. The general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (z-VAD.fmk) blocked the p53-induced apoptosis in 3-2 cells, with a concomitant elevation of p27(Kip1), suggesting that p27(Kip1) protein underwent caspase-dependent proteolysis in the apoptotic 3-2 cells. Together these results linked a pathway involving cytochrome c release, caspase activation and p27(Kip1) degradation to the p53-induced apoptosis in IW32 erythroleukemia cells.
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PMID:Modulation of caspase activation and p27(Kip1) degradation in the p53-induced apoptosis in IW32 erythroleukemia cells. 1222 Jun 22

Numerous upstream stimulatory and inhibitory signals converge to the pRb/E2F pathway, which governs cell-cycle progression, but the information concerning alterations of E2F-1 in primary malignancies is very limited. Several in vitro studies report that E2F-1 can act either as an oncoprotein or as a tumour suppressor protein. In view of this dichotomy in its functions and its critical role in cell cycle control, this study examined the following four aspects of E2F-1 in a panel of 87 non-small cell lung carcinomas (NSCLCs), previously analysed for defects in the pRb-p53-MDM2 network: firstly, the status of E2F-1 at the protein, mRNA and DNA levels; secondly, its relationship with the kinetic parameters and genomic instability of the tumours; thirdly, its association with the status of its transcriptional co-activator CBP, downstream target PCNA and main cell cycle regulatory and E2F-1-interacting molecules pRb, p53 and MDM2; and fourthly, its impact on clinical outcome. The protein levels of E2F-1 and its co-activator CBP were significantly higher in the tumour area than in the corresponding normal epithelium (p<0.001). E2F-1 overexpression was associated with increased E2F-1 mRNA levels in 82% of the cases examined. The latter finding, along with the low frequency of E2F-1 gene amplification observed (9%), suggests that the main mechanism of E2F-1 protein overexpression in NSCLCs is deregulation at the transcriptional level. Mutational analysis revealed only one sample with asomatic mutation at codon 371 (Glu-->Asp) and one carrying a polymorphism at codon 393 (Gly-->Ser). Carcinomas with increased E2F-1 positivity demonstrated a significant increase in their growth indexes (r=0.402, p=0.001) and were associated with adverse prognosis (p=0.033 by Cox regression analysis). The main determinant of the positive association with growth was the parallel increase between E2F-1 staining and proliferation (r=0.746, p<0.001), whereas apoptosis was not influenced by the status of E2F-1. Moreover, correlation with the status of the pRb-p53-MDM2 network showed that the cases with aberrant pRb expression displayed significantly higher E2F-1 indexes (p=0.033), while a similar association was noticed in the group of carcinomas with deregulation of the p53-MDM2 feedback loop. In conclusion, the results suggest that E2F-1 overexpression may contribute to the development of NSCLCs by promoting proliferation and provide evidence that this role is further enhanced in a genetic background with deregulated pRb-p53-MDM2 circuitry.
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PMID:Transcription factor E2F-1 acts as a growth-promoting factor and is associated with adverse prognosis in non-small cell lung carcinomas. 1223 72

This study examined the role of nitric oxide (NO) in cytokine-induced apoptosis in adult cardiac fibroblasts (CFbs). In cultured adult rat CFbs, IL-1beta (5 ng/ml), but not interferon-gamma (10 ng/ml) or tumor necrosis factor-alpha (10 ng/ml), induced inducible NO synthase (iNOS) expression and NO production that was associated with an increase in caspase-3 activity and apoptotic cell death. Apoptotic frequency was reduced by the iNOS inhibitor S-methylisothiourea (3 x 10(-5) M). Apoptosis in response to IL-1beta was attenuated by the caspase-3 inhibitor [Z-Asp-Glu-Val-Asp-fluoromethyl ketone (Z-DVED-FMK)] but not by inhibition of guanylyl cyclase with 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). IL-1beta-induced CFb apoptosis was associated with an increase in p53 and Bax protein expression with no changes in Bcl-2 or Bcl-x(L). Nuclear condensation and fragmentation occurred when isolated nuclei were exposed to an NO donor [Z-1[N-(2-aminoethyl)-N-(2-ammonoethyl)amino]diazen-1-ium-1,2-dioate (DETA-NONOate) 10(-5) M], an effect that was not blocked by the peroxynitrite scavenger Mn(III)tetrakis(4-benzoic acid) porphyrin chloride. Moreover, Mn(III)tetrakis(4-benzoic acid) porphyrin chloride attenuated but did not eliminate IL-1beta-induced CFb apoptosis, indicating that the proapoptotic effect of NO can occur independently of its conversion to peroxynitrite. Our results demonstrate that IL-1beta-induced iNOS expression can trigger NO-dependent apoptosis in adult CFbs, which appears to result from DNA damage and may be mediated by a p53-dependent apoptotic pathway.
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PMID:Mechanisms of cytokine induced NO-mediated cardiac fibroblast apoptosis. 1238 74

Previous studies have demonstrated the irradiation-induced phosphorylation of p53 at Thrl8 and Ser20, residues integral within an a-helical segment of the transactivation domain. Importantly, phosphorylation at either site has been correlated with decreased binding to the inhibitory partner Mdm-2 and enhanced transactivation of p53 target genes. In this study, we investigated the impact of Asp substitution at Thrl8 and Ser20 (p53Tl8D/S20D) on the functional regulation of p53. Asp substitution is commonly accepted as a means of mimicking phosphorylation due to the introduction of negative charge within the functional group. p53T18D/S20D was refractory to in vitro digestion by calpain, a protease recognizing a-helical structure within the transactivation domain. In addition, transfected p53T18D/S20D poorly bound GST-Mdm-2 in vitro, enhanced the endogenous expression of the p53 transactivation targets p21(Waf1/Cip1) and fas/APO-1, and significantly curtailed cell proliferation relative to wild-type p53 transfected cells. Thus, Asp substitution at Thr18 and Ser20 within the a-helical segment of the transactivation domain reduced Mdm-2 interaction, upregulating transactivation of cell-cycle and apoptotic regulatory targets, curtailing cellular proliferation.
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PMID:p53 Antiproliferative function is enhanced by aspartate substitution at threonine 18 and serine 20. 1243 78

We assessed the ability of cryptophycin 52 (LY355703), a novel antimicrotubule, to induce growth arrest and apoptosis in prostate cancer cell lines and investigated potential molecular mechanisms of death. LNCaP (androgen-dependent) and DU-145 (androgen-independent) cells accumulated in G(2)-M phase of the cell cycle and progressively acquired sub-G(0)-G(1) DNA content after 48 h of exposure to cryptophycin 52 (1-10 pM). Induction of apoptosis was confirmed by DNA ladder formation and detection of cytoplasmic nucleosomes. PC-3 (androgen-independent) cells were less responsive to cryptophycin 52-induced death. Apoptosis was associated with proteolytic processing and activation of the caspase-3-like subfamily proteins caspase-3 and caspase-7 and cleavage of the caspase substrate poly(ADP-ribose) polymerase. The pan-caspase inhibitor BOC-Asp(OMe)-fluoromethylketone effectively reduced cryptophycin 52-induced caspase-3-like protease activity and apoptosis in DU-145 cells. In contrast, BOC-Asp(OMe)-fluoromethylketone did not inhibit apoptosis induction in LNCaP cells by cryptophycin 52, even though both cryptophycin 52-induced caspase-3-like activity and staurosporine-induced death were blocked under identical conditions. Cryptophycin 52 induced phosphorylation of c-raf1 and bcl-2 and/or bcl-x(L) to comparable levels in all cell lines studied, and LNCaP cells overexpressing bcl-2 were more resistant to cryptophycin 52-induced apoptosis. Up-regulation of p53, bax, and p21 expression was induced in wild-type p53-expressing LNCaP cells only after cryptophycin 52 exposure. A sustained increase in c-Jun NH(2)-terminal kinase phosphorylation was also observed, the levels of which strongly correlated with apoptosis. We conclude that apoptosis induced by cryptophycin 52 in prostate cancer cells is androgen status independent, cell type specific for caspase requirement, modulated by the bcl-2 family, linked to but not dependent on p53, and strongly correlated with c-Jun NH(2)-terminal kinase phosphorylation. Cryptophycin 52-induced apoptosis in prostate cancer cells is therefore associated with multiple cell line-specific alterations in apoptosis-associated proteins and pathways.
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PMID:The novel antimicrotubule agent cryptophycin 52 (LY355703) induces apoptosis via multiple pathways in human prostate cancer cells. 1247 8

Azurin is a copper-containing protein involved in electron transfer during denitrification. We reported recently that purified azurin demonstrates cytotoxicity to macrophages by forming a complex with the tumour-suppressor protein p53, thereby stabilizing it and enhancing its function as an inducer of proapoptotic activity (Yamada, T., Goto, M., Punj, V., Zaborina, O., Kimbara, K., Das Gupta, T. K., and Chakrabarty, A. M. 2002, Infect Immun70: 7054-7062). It is, however, not known whether the oxidoreductase (redox) activity of azurin or the involvement of copper is important for its cytotoxicity. We have isolated apo-azurin devoid of copper and site-directed mutants that are redox negative because of either replacement of a cysteine residue (Cys-112) involved in co-ordination with copper or mutational replacement of two methionine residues (Met-44 and Met-64) that are present in the hydrophobic patch of azurin and allow interaction of azurin with its redox partner cytochrome c551. We demonstrate that, although the wild type (wt) and the Cys-112 Asp mutant azurin can form complexes with the tumour-suppressor protein p53 and generate high levels of reactive oxygen species (ROS), the redox-negative Met-44LysMet-64Glu mutant azurin is defective in complex formation with p53, generates low levels of ROS and lacks appreciable cytotoxicity towards macrophages. Thus, complex formation with p53 and ROS generation, rather than azurin redox activity, are important in the cytotoxic action of azurin towards macrophages.
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PMID:Induction of apoptosis in macrophages by Pseudomonas aeruginosa azurin: tumour-suppressor protein p53 and reactive oxygen species, but not redox activity, as critical elements in cytotoxicity. 1251 4


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