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)

Technological developments have made possible extension of polymerase chain reaction (PCR) analysis to individual cells to localize DNA/RNA with non-radioactive labels at the light microscopic level. This approach, in situ PCR, is particularly useful in resolving low-frequency message expression in mixed populations of cells and tissues. We have established a working protocol for direct in situ PCR and have utilized several controls to validate our results. In this report we outline the procedures for detecting either DNA or RNA in a rapid and reproducible manner. We evaluate the sequential steps required for this analysis, such as protease hydrolysis, DNAse digestion, "hot start" capabilities, and detection methods. We have applied these methods in several applications, including detection of the p53 gene in human tumor samples, localization of insulin-like growth factor-IA mRNA in cell lines with low levels of expression, and distribution of transferrin mRNA in lung cancer cell lines and tumors. We demonstrate from this study that the in situ PCR technique is an investigative approach capable of detecting specific DNA/RNA sequences at the cellular level and of identifying cells with low levels of mRNA expression.
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PMID:Non-radioactive localization of nucleic acids by direct in situ PCR and in situ RT-PCR in paraffin-embedded sections. 754 78

Transcriptional activation of target genes represents an important component of the tumour-suppressor function of p53 and provides a functional link between p53 and various growth-regulatory processes, including cell cycle progression (p21/WAF1), DNA repair (GADD45) and apoptosis (bax). Here we use a differential cloning approach to identify the gene encoding insulin-like growth factor binding protein 3 (IGF-BP3) as a novel p53-regulated target gene. Induction of IGF-BP3 gene expression by wild-type but not mutant p53 is associated with enhanced secretion of an active form of IGF-BP3 capable of inhibiting mitogenic signalling by the insulin-like growth factor IGF-1. Our results indicate that IGF-BP3 may link p53 to potential novel autocrine/paracrine signalling pathways and to processes regulated by or dependent on IGF(s), such as cellular growth, transformation and survival.
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PMID:Induction of the growth inhibitor IGF-binding protein 3 by p53. 756 79

The neuroendocrine protein 7B2 prevents premature activation of PC2, an enzyme involved in the processing of prohormones in the secretory pathway. We inquired if this chaperone-like function encompasses a broader role for 7B2 in the folding of hormone-like proteins. As a test, the fate of misfolded human insulin-like growth factor-1 (IGF1) was assessed, in the presence and absence of 7B2. Most of the recombinant IGF1 molecules, secreted from yeast, are a conglomeration of inactive multimers which are either disulfide-linked or mere physical aggregates. We find that yeast-produced 7B2 influences the in vitro conversion of inactive molecules into active monomers. However, the amounts of disulfide-linked dimers remain unaffected during this conversion. Interestingly, both 7B2 and the molecular chaperone DnaK interact with IGF1 in the yeast two-hybrid system. Like DnaK, 7B2 also binds the tumor suppressor protein p53. Binding of DnaK to exposed epitopes of aggregated proteins is known to be a prerequisite for deaggregation. It is conceivable that 7B2 participates in an analogous manner in the dissociation of non-covalently linked multimers of IGF1. Our results indicate that 7B2 might find an application in the deaggregation of potentially useful therapeutic proteins.
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PMID:The neuroendocrine protein 7B2 acts as a molecular chaperone in the in vitro folding of human insulin-like growth factor-1 secreted from yeast. 779 52

Findings from molecular genetic and cytogenetic investigations suggest that mutations in suppressor genes play a key role in osteosarcoma pathogenesis. RB and p53 are frequently involved and are speculated to be indispensable components. Alterations in putative suppressor genes on chromosomes 18q and 3q additionally may be involved in various patterns. The high resolution of magnetic resonance imaging in osteosarcoma imaging is confirmed, and the validity of dynamic gadolinium-enhanced imaging for estimation of tumor response is stated. The efficacy of single-drug high-dose methotrexate convincingly is shown to be 19%. Phase II trials with nonspecific immunostimulation using a synthetic liposomal mycobacterium-derived antigen (liposomal muramyl tripeptide phosphatidylethanolamine) do not yet allow us to draw conclusions on eventual efficacy. A novel and promising approach may be intervention in the endocrine or orthocrine and paracrine tumor growth regulation. Hypophysectomy in mice dramatically reduced plasma or insulin-like growth factor and local as well as systemic growth of transplanted osteosarcoma. The close interrelation between tumor response, surgical margins, and local control is demonstrated, as well as the fatal prognosis after local failure. Also, the validity of known risk factors in patients undergoing intensive chemotherapy has been confirmed. Interestingly, dose intensity was not found to influence prognosis.
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PMID:Osteosarcoma. 836 83

The molecular role of hepatitis C virus (HCV) in liver disease has yet to be clarified. In this study, we analyzed the relationship of HCV replication with mRNA expression of growth factors and mutation of tumor suppressor gene, ie, transforming growth factor-beta 1 (TGF-beta 1), which promotes cirrhotic changes; TGF-alpha, insulin-like growth factor-II (IGF-II), which are both related to hepatocyte transformation; and tumor suppressor gene p53, which is associated with HCC progression. A semiquantitative RNA polymerase chain reaction (RNA-PCR) was used to analyze genetic expression in 31 cirrhotic liver specimens from patients with HCV. In order to detect HCV replication, the minus-strand RNA of HCV, which serves as a template for the synthesis of genomic plus-strand RNA, was examined. The expression of the growth factors was semiquantified by RNA-PCR, and the mutation of p53 was detected using PCR-single-strand conformation polymorphism. According to the semiquantitative analysis, HCV replication was not associated with the expression of TGF-beta 1 but was significantly so with the overexpression of TGF-alpha (r = 0.74) and IGF-II (r = 0.65) in the HCV-positive cirrhotic livers. No mutation of p53 was recognized in any of the samples. Our investigation thus suggested that the replication of HCV might mediate the coexpression of TGF-alpha and IGF-II and act as a possible initiating factor for hepatocarcinogenesis.
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PMID:Hepatitis C virus replication is associated with expression of transforming growth factor-alpha and insulin-like growth factor-II in cirrhotic livers. 856 58

Human insulin-like growth factor (IGF)-II mRNA has been shown to be expressed at high levels in a variety of tumors, including rhabdomyosarcomas. In addition, many tumors have alterations in p53 expression. To investigate whether p53 regulates IGF-II gene expression, we transfected wild-type p53 expression vectors and luciferase constructs driven by IGF-II P3 promotors into multiple cell lines. We found that p53 reduced, in a dose-dependent manner, both endogenous IGF-II P3 transcripts and transfected P3 luciferase expression. The inhibition of P3 luciferase expression by p53 was more pronounced in the two cell lines that expressed mutant p53 protein, RD, and HTB114. The element responsible for this inhibition was mapped to the minimal promoter region. We also transfected an HPV-16 E6 expression plasmid into CCL13 cells containing functional p53 and found that E6 up-regulated IGF-II P3 activity. Wild-type, but not mutant, p53 interfered with the binding of TATA-binding protein to the TATA motif of P3, although both could directly associate with human TATA-binding protein. Our results suggest that p53 may play a role in regulation of IGF-II gene expression.
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PMID:Regulation of insulin-like growth factor II P3 promotor by p53: a potential mechanism for tumorigenesis. 864 Aug 27

mac25, a retinoic acid-inducible gene that is expressed at high levels in senescent epithelial cells, was initially cloned as a gene that is differentially expressed in meningioma. Although the homology of its product with members of family of insulin-like growth factor-binding proteins was suggested, the product also exhibits strong homology to follistatin, an activin-binding protein. However, a domain corresponding to the carboxyl terminus of follistatin is not found in mac25. The carboxyl-terminally truncated form of follistatin, generated by alternative splicing, has stronger activin-binding activity than the complete form. This result suggests that mac25 might act as an activated follistatin. Clonal growth of a p53-deficient osteosarcoma cell line was strongly inhibited when the murine mac25 gene, as well as the p53 gene, was introduced. Resembling activins that belong to the transforming growth factor-beta (TGF-beta) superfamily, mac25 and p53 might associate with similar but distinct targets, namely cyclin-dependent kinase inhibitors. However, there is no evidence for compensation of p53 function by mac25 in the development of p53-deficient mice, as judged from the pattern of expression of mac25 in mice. mac25 might act as a tumor suppressor, modulating signaling of the TGF-beta family, as does alpha-inhibin.
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PMID:A follistatin-like gene, mac25, may act as a growth suppressor of osteosarcoma cells. 864 39

There is strong evidence to suggest that insulin and insulin-like growth factor (IGF)-I may be important for tumor growth. Both the insulin and IGF-I receptors (IGF-IR) are overexpressed in breast cancer, and antibody blockade of the IGF-IR inhibits the growth of some breast cancer cell lines. Furthermore, expression of an insulin receptor (IR) in a normal mammary epithelia] cell line causes insulin-dependent transformation. Functional inactivation of p53 is also very frequent in many tumors. In this paper, we investigated whether inactivation of p53 might be involved in the overexpression of the IR in malignancy, specifically breast cancer. We demonstrate a positive correlation between IR and IGF-IR levels and p53 overexpression in primary human breast malignancies. To examine possible mechanisms by which p53 may regulate IR gene expression, we show that p53 can repress the IR promoter and that a dominant-negative p53 (248Q) can de-repress the promoter in cells containing normal p53. The p53 effect was shown to be mediated by C/EBP and Sp1 transcription factors. We also documented that p53-null mice had elevated levels of Sp1, but not C/EBPalpha, and that insulin binding to liver extracts was increased compared to wild-type controls. These results suggest that p53 inactivation may lead to an up-regulation of genes, such as the IR, that are dependent on these transcription factors.
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PMID:Repression of the insulin receptor promoter by the tumor suppressor gene product p53: a possible mechanism for receptor overexpression in breast cancer. 866 14

The p53 tumor suppressor protein is a sequence-specific transcriptional activator, a function which contributes to cell cycle arrest and apoptosis induced by p53 in appropriate cell types. Analysis of a series of p53 point mutants has revealed the potential for selective loss of the ability to transactivate some, but not all, cellular p53-responsive promoters. p53 175P and p53 181L are tumor-derived p53 point mutants which were previously characterized as transcriptionally active. Both mutants retained the ability to activate expression of the cyclin-dependent kinase inhibitor p2lcip1/waf1, and this activity correlated with the ability to induce a G1 cell cycle arrest. However, an extension of this survey to include other p53 targets showed that p53 175P was defective in the activation of p53-responsive sequences derived from the bax promoter and the insulin-like growth factor-binding protein 3 gene (IGF-BP3) promoter, while p53 181L showed loss of the ability to activate a promoter containing IGF-BP3 box B sequences. Failure to activate transcription was also reflected in the reduced ability of the mutants to bind the p53-responsive DNA sequences present in these promoters. These specific defects in transcriptional activation correlated with the impaired apoptotic function displayed by these mutants, and the results suggest that activation of cell cycle arrest genes by p53 can be separated from activation of genes with a role in mediating the p53 apoptotic response. The cellular response to p53 activation may therefore depend, at least in part, on which group of p53-responsive genes become transcriptionally activated.
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PMID:Differential activation of target cellular promoters by p53 mutants with impaired apoptotic function. 875 54

Human wild-type (wt) p53 can induce apoptosis in transiently transfected H1299 cells maintained at 37 degrees C, whereas tumor-derived mutant forms of p53 (with the mutation Ala-143, His-175, or Trp-248) fail to do so. At 37 degrees C, p53 with a mutation to Ala at amino acid 143 (p53Ala143) was transcriptionally inactive. However, at 32 degrees C, p53Ala143 strongly activated transcription from several physiologically relevant p53-responsive promoters, to extents similar or greater than that of wt p53. Unexpectedly, p53Ala143 was defective in inducing apoptosis in H1299 cells at 32 degrees C. Concomitantly with the loss of apoptotic activity, p53Ala143 was found to be deficient in its ability to activate transcription from the p53-responsive portions of the Bax and insulin-like growth factor-binding protein 3 gene promoters. It is proposed that there may exist distinct classes of p53-responsive promoters, whose ability to be activated by p53 can be regulated differentially. Such differential regulation may have functional consequences for the effects of p53 on cell fate.
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PMID:A mutant p53 that discriminates between p53-responsive genes cannot induce apoptosis. 875 55


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