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)

Recombinant adenovirus (Adv)-mediated gene transduction is a powerful technology for cancer gene therapy. In this article, we report the generation of a fiber-mutant Adv vector, using the Adv genomic DNA-terminal protein complex (DNA-TPC) cotransfection method. First, a fiber-mutant construct in a plasmid carrying the right-side two-thirds of the human adenovirus type 5 (Ad5) genome (pTR) was cotransfected with Ad5 DNA-TPC, yielding the recombinant Adv with the desired fiber mutation. The DNA-TPC from the mutant Adv was then utilized to produce a second-step recombinant Adv with an expression cassette in the place of E1. By this procedure, we generated a fiber mutant, F/K20, that has a linker and a stretch of 20 lysine residues added at the C terminus of the fiber. By using Adv carrying a reporter lacZ gene (AxCAZ2) with either F/K20 or wild-type fiber (F/wt), we examined the transduction efficiency of F/K20-Adv. No significant difference in the transduction efficiency between F/K20 and F/wt-Adv was observed for a human fibroblast line, WI-38, or various tumor cell lines, including melanoma, prostate, esophageal, and pancreatic cancer lines. In clear contrast, F/K20-Adv showed a remarkably enhanced efficiency in genetic transduction of human glioma cells. In all four human glioma lines tested, the multiplicities of infection (MOIs) for transduction of 50% of the population (ED50) were decreased with F/K20-Adv compared with F/wt-Adv: 7-fold for T98G, 14-fold for U251, 9-fold for U373, and 42-fold for U87 cells. Therefore, we attempted to apply F/K20-Adv for gene therapy of malignant glioma. Glioma cells infected with F/K20-Adv carrying genes for interleukin 2 or interleukin 12 produced a high level of each cytokine at a much lower MOI than did cells infected with F/wt-Adv. Infection with F/K20-Adv carrying the wild-type p53 tumor suppressor gene resulted in an enhanced level of p53 protein expression and an increased incidence of F/K20-Adv in transduction efficiency for malignant glioma, providing promising tools for gene therapy.
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PMID:Generation of fiber-mutant recombinant adenoviruses for gene therapy of malignant glioma. 985 17

The p53 tumor suppressor protein is a sequence-specific transcription factor that modulates the response of cells to DNA damage. Recent studies suggest that full transcriptional activity of p53 requires the coactivators CREB binding protein (CBP)/p300 and PCAF. These coactivators interact with each other, and both possess intrinsic histone acetyltransferase activity. Furthermore, p300 acetylates p53 to activate its sequence-specific DNA binding activity in vitro. In this study, we demonstrate that PCAF also acetylates p53 in vitro at a lysine residue distinct from that acetylated by p300 and thereby increases p53's ability to bind to its cognate DNA site. We have generated antibodies to acetylated p53 peptides at either of the two lysine residues that are targeted by PCAF or p300 and have demonstrated that these antibodies are highly specific for both acetylation and the particular site. Using these antibodies, we detect acetylation of these sites in vivo, and interestingly, acetylation at both sites increases in response to DNA-damaging agents. These data indicate that site-specific acetylation of p53 increases under physiological conditions that activate p53 and identify CBP/p300 and PCAF as the probable enzymes that modify p53 in vivo.
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PMID:p53 sites acetylated in vitro by PCAF and p300 are acetylated in vivo in response to DNA damage. 989 Oct 54

A synthetic 22-mer peptide (peptide 46) derived from the p53 C-terminal domain can restore the growth suppressor function of mutant p53 proteins in human tumor cells (G. Selivanova et al., Nat. Med. 3:632-638, 1997). Here we demonstrate that peptide 46 binds mutant p53. Peptide 46 binding sites were found within both the core and C-terminal domains of p53. Lys residues within the peptide were critical for both p53 activation and core domain binding. The sequence-specific DNA binding of isolated tumor-derived mutant p53 core domains was restored by a C-terminal polypeptide. Our results indicate that C-terminal peptide binding to the core domain activates p53 through displacement of the negative regulatory C-terminal domain. Furthermore, stabilization of the core domain structure and/or establishment of novel DNA contacts may contribute to the reactivation of mutant p53. These findings should facilitate the design of p53-reactivating drugs for cancer therapy.
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PMID:Reactivation of mutant p53 through interaction of a C-terminal peptide with the core domain. 1020 63

Since the p53 gene function is critical to how a cell responds to DNA damage, we investigated the p53 status in Chinese hamster cell lines commonly used in genotoxicity tests for cytogenetic damage around the world. These included: Chinese hamster ovary K1 (CHO-K1), Chinese hamster ovary WBL (CHO-WBL), and Chinese hamster lung (CHL) cells. The results of DNA sequencing, protein analysis, and cell cycle analysis demonstrate that the CHO-K1 and CHO-WBL cell lines have mutant p53 sequence [a mutation in codon 211 in exon 6 resulting in a change from Thr (ACA) to Lys (AAA)], mutant protein (high spontaneous levels that are non-inducible after X-irradiation), and mutant function (lack of G1 checkpoint). Interestingly, the CHL cell line has a completely wild-type p53 DNA sequence. However, the CHL cells have an abnormally high spontaneous level of wild-type p53 protein expression that is not inducible after X-irradiation, yet there is some evidence of G1 delay after irradiation. The protein data suggests that p53 in CHL cells is not being regulated normally, and thus is probably not functioning normally. The mechanism leading to this abnormal regulation of p53 in CHL cells clearly does not involve mutation in the p53 gene. Overall, the CHL cell line may be similar to the CHO cell lines, in that they all appear to have abnormal p53 function. Further work is needed to determine whether the presence of spontaneously high levels of wild-type p53 in CHL cells results in a difference in response to DNA damage (quantitatively or qualitatively) compared to the p53 mutant CHO cell lines.
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PMID:Characterization of p53 in Chinese hamster cell lines CHO-K1, CHO-WBL, and CHL: implications for genotoxicity testing. 1032 Jul 50

It has been reported that Lysine-305 is needed for the nuclear import of the p53 protein (Liang et al., 1998). In the present study, further mutagenesis analyses were carried out between Lys-305 and the major nuclear localization signal (NLS I) of p53. It was found that a single mutation of Arg-306 resulted in the defect of p53 nuclear import. This effect is the same as that of Lys-305 mutation. Other mutations between Arg-306 and NLS I have no effect on the nuclear import of p53. However, deletions of more than two amino acids between this region abolished the transport of p53 into the nucleus. These results indicate that a basic domain other than the well defined NLS is required for the nuclear import of p53. A spacer between this basic domain and NLS I is necessary for the entrance of p53 into the cell nucleus.
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PMID:The nuclear import of p53 is determined by the presence of a basic domain and its relative position to the nuclear localization signal. 1032 42

Using polymerase chain reaction single strand conformation polymorphism analysis (PCR-SSCP), the authors mutations in exon 5, 7 and 8 of the p53 gene in lung cancer tissue from 15 of 36 silicotic patients. Mutations existed in exon 5, exon 7 and exon 8, but occured more frequently in exon 8. The authors also found that p53 gene mutation rate in lung adenocarcinomas of silicotic patients was higher than that of those without silicosis. A single base substitution was found by DNA sequencing analysis in sample C8. As a result, No. 144 codon was mutated from CAG to AAG, so Gln was substituted by Lys. The authors' data suggest that p53 mutation may play an important role in the pathogenesis of lung cancer of silicotic patients.
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PMID:[The research on p53 gene mutation in lung cancer tissue of silicotic patients by PCR-SSCR]. 1032 39

Paraffin embedded tissues from twenty-two Thai patients with non-small cell lung cancer were studied for p53 gene mutations in exon 5 to 8 using polymerase chain reaction and single-stranded conformation polymorphism (PCR-SSCP) followed by thermal cycle sequencing. Results showed that point mutations in this region of p53 gene were present in 3 cases. One harboured the base change from GAC to AAC at codon 281, changing amino acid from aspartic acid to asparagine, whilst the other cases were transversion of AAA (lysine) to ACA (threonine) at codon 292. All subjects with p53 mutation had a past history of tobacco smoking.
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PMID:p53 gene mutations in non-small cell lung cancer from Thai patients. 1041 Apr 79

An E1B 55-kDa gene-defective adenovirus (Adv), ONYX-015, has been reported to be a highly useful replication-competent Adv that shows cytopathic effect for cancers with an abnormal p53 gene, without damaging normal tissues. In this study, we combined this Adv (Adv-E1AdB) with a fiber mutation, F/K20, which has a stretch of 20 lysine residues added at the COOH-terminus of the fiber and shows high transduction efficiency to gliomas. In U-373 MG glioma cells, the transduction efficiency of Adv-F/ K20 for lacZ was nine times higher than that of the Adv with wild-type fiber (Adv-F/wt) for lacZ. At a multiplicity of infection of 30, the replication efficiency of Adv-E1AdB-F/K20 was 11 times higher than that of Adv-E1AdB with wt fiber (Adv-E1AdB-F/wt). The ED50 value of AdvE1AdB-F/K20 to U-373 MG cells, which is a measure of the in vitro cytopathic effect, was 32 times greater than that of Adv-E1AdB-F/wt. injection of Adv-E1AdB-F/K20 suppressed the in vivo growth of tumors. The antitumoral effect of Adv-E1AdB-F/K20 was remarkably stronger than that of Adv-E1AdB-F/wt. A greater quantity of replicated virus protein (hexon) by infection with Adv-E1AdB-F/K20 was demonstrated in vitro and in vivo, compared with that of Adv-E1AdB-F/wt. In conclusion, gene therapy using Adv-E1AdB-F/K20, which drastically augmented the antitumoral effect of Adv-E1AdB, will be a promising therapeutic approach for gliomas.
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PMID:Highly augmented cytopathic effect of a fiber-mutant E1B-defective adenovirus for gene therapy of gliomas. 1041 3

The cellular and molecular mechanisms of radiation-induced lung cancer are not known. In the present study, alterations of p53 in tumorigenic human papillomavirus-immortalized human bronchial epithelial (BEP2D) cells induced by a single low dose of either alpha-particles or 1 GeV/nucleon (56)Fe were analyzed by PCR-single-stranded conformation polymorphism (SSCP) coupled with sequencing analysis and immunoprecipitation assay. A total of nine primary and four secondary tumor cell lines, three of which were metastatic, together with the parental BEP2D and primary human bronchial epithelial (NHBE) cells were studied. The immunoprecipitation assay showed overexpression of mutant p53 proteins in all the tumor lines but not in NHBE and BEP2D cells. PCR-SSCP and sequencing analysis found band shifts and gene mutations in all four of the secondary tumors. A G-->T transversion in codon 139 in exon 5 that replaced Lys with Asn was detected in two tumor lines. One mutation each, involving a G-->T transversion in codon 215 in exon 6 (Ser-->lle) and a G-->A transition in codon 373 in exon 8 (Arg-->His), was identified in the remaining two secondary tumors. These results suggest that p53 alterations correlate with tumorigenesis in the BEP2D cell model and that mutations in the p53 gene may be indicative of metastatic potential.
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PMID:Alterations of p53 in tumorigenic human bronchial epithelial cells correlate with metastatic potential. 1042 2

Bcl-2 family proteins and interleukin-1-beta converting enzyme/Caenorhabditis elegans cell death gene-3 (ICE/CED-3) family proteases (caspases) represent the basic regulators of apoptosis. However, the precise mechanism by which they interact is unclear. In this study, we found that gamma-radiation-induced apoptosis of leukemia cells was associated with activation of multiple caspases and bax up-regulation. Membrane changes and caspase activities were suppressed by specific caspase inhibitors. Similarly, the serine protease inhibitors z-Ala-Ala-Asp-cmk (AAD) and tosyl-lysine chloromethyl ketone (TLCK) also prevented caspase activation and poly(ADP-ribose) polymerase cleavage in vivo but had no effect on caspase activity in vitro. TLCK also prevented bax up-regulation as a result of its inhibitory effect on p53 function. Inhibitors of caspases and serine proteases partially prevented cell death, suggesting a caspase involvement in Bax-mediated cell death. We propose an ordering of signaling events in Bax-mediated cell death, including steps upstream and downstream of p53 and bax up-regulation.
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PMID:Ionizing radiation-induced, Bax-mediated cell death is dependent on activation of cysteine and serine proteases. 1043 17


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