Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The transfer of apoptosis genes to tumors is one of the most promising strategies for cancer gene therapy. We have shown that massive apoptosis occurs when wild-type p53 expression is induced in glioma cells carrying a p53 gene mutation. However, adenovirus-mediated p53 gene transfer is ineffective in causing apoptosis in glioma cells that retain a wild-type p53 genotype. We evaluated the effect of E2F-1 overexpression on the growth of gliomas in vitro and in vivo. In the in vitro study, the adenovirus-mediated transfer of exogenous E2F-1 protein precipitated generalized apoptosis in gliomas. The treatment with Ad5CMV-E2F-1 of nude mice carrying subcutaneous gliomas arrested tumor growth. Our results indicate that E2F-1 has anti-glioma activity in vitro and in vivo.
 ...
PMID:Overexpression of E2F-1 in glioma triggers apoptosis and suppresses tumor growth in vitro and in vivo. 962 77

Epstein-Barr virus (EBV) has been detected in the large majority of HIV-related primary central nervous system lymphomas (PCNSL) suggesting a pathogenetic role of the virus. Unlike HIV-related PCNSL, conflicting data exist with regard to the presence of EBV in non immunodeficiency-related (sporadic) PCNSL. For this reason, a population based material of 41 sporadic PCNSL was analysed for the presence of EBV genome (EBER, BHLF) using RNA in situ hybridisation (RISH). Furthermore, the expression of the gene products of the bcl-2 oncogene and the p53 tumor suppressor gene and the tumor growth fraction reactive with the monoclonal antibody Ki-67 have been evaluated. All cases but two were EBV genome negative. In the two positive cases less than 5% of tumor cells showed EBER positivity. In contrast, more than 75% of cells morphologically belonging to the tumor-cell population stained positively for EBER in two cases of HIV related PCNSL. Immunostaining for the bcl-2 oncoprotein was positive in 28 (72%) of 39 cases examined. In most cases more than 75% of tumor cells showed cytoplasmic expression. Of 37 cases investigated for p53 expression, 21 (57%) stained positively. However, in the large majority of positive cases less than 10% of the neoplastic cells stained. The percentage of Ki-67 positive cells ranged between 10% and 80% with a mean of 50%. The expression of the p53 and bcl-2 oncoproteins and the growth fraction did not have any prognostic impact. We conclude that the EBV genome is rarely detected in sporadic PCNSL, indicating that a pathogenetic role of EBV is unlikely. Like extracerebral B-cell lymphomas a large fraction of PCNSL expresses the p53 and bcl-2 oncoproteins, a feature, however, which does not seem to have prognostic implications.
 ...
PMID:Primary central nervous system lymphomas in immunocompetent individuals: histology, Epstein-Barr virus genome, Ki-67 proliferation index, p53 and bcl-2 gene expression. 966 83

p53 tumor suppressor gene therapy has been proposed for cancers characterized by inactivation of p53 function, and successful therapy will require efficient strategies for gene delivery. To maximize transgene expression in tumors, a clinical strategy has been proposed to treat neoplasms in the liver via hepatic artery administration of a recombinant adenovirus encoding wild-type p53 (rAd-p53). We have developed a syngeneic rat model using a p53mut hepatocellular carcinoma cell line (McA-RH7777) that results in multifocal liver tumor nodules to provide experimental support for this strategy. Treatment of McA-RH7777 cells with rAd-p53 in vitro resulted in efficient transgene expression, growth suppression, and apoptosis. Intrahepatic artery dosing with rAd-p53 or an adenovirus encoding beta-galactosidase (rAd-betagal) increased transgene expression in tumor tissue and decreased systemic exposure when compared with i.v. dosing. Daily hepatic artery dosing of rAd-p53 suppressed tumor growth when compared with untreated rats or animals treated with rAd-betagal. These data demonstrate the potential for arterial gene delivery to tumors using recombinant adenoviruses, and support continued investigation of rAd-p53 gene therapy for liver malignancies.
 ...
PMID:p53 gene therapy in a rat model of hepatocellular carcinoma: intra-arterial delivery of a recombinant adenovirus. 967 39

Tumor angiogenesis is a fundamental step in tumor growth and proliferation. Fumagillin is an anti-angiogenic agent which is secreted by Aspergillus, but is also toxic. A fumagillin analogue, TNP-470, has been developed which is a potent angiogenic inhibitor with few side effects. TNP-470 has inhibited tumor growth in Lewis lung cancer and melanoma in animal models. This study was designed to test this proven anti-angiogenic agent's effects on head and neck cancer growth. Fort,v Harlan nude mice were injected subcutaneously with cancer cells from a human oral squamous cell carcinoma. After 3 weeks of tumor growth 25 mice were injected with TNP-470 subcutaneously at a distant site every other day for 30 days while 10 control mice received saline injections. Five mice began TNP-470 injections at the time of tumor injection to determine if TNP-470 can prevent tumor development. The tumor growth and development was unaffected by TNP-470 as compared to the control group. Therefore, the use of an angiogenic inhibitor had no effect on oral cancer growth. Analysis of the cell line utilized found abnormal mRNA expression, which included high p53 expression and low cyclin Dl expression. These results suggest that oral cancers are less dependent on angiogenesis than other tumor types. The genetic abnormalities may explain the angiogenesis independence that was demonstrated. Results found in other tumor types with angiogenic inhibitors cannot be extrapolated to oral cancer since genetic mutations may allow oral tumors to grow without neovascularization.
 ...
PMID:Angiogenic inhibition for the treatment of head and neck cancer. 970 16

The p53 tumor supressor gene is the most frequently mutated gene in human cancers. Approximately 40% of astrocytic tumors have alterations of the p53 gene, which are considered to play an important role in tumorigenicity and malignant progression. Since the main functions of normal p53 are cell-cycle regulation and induction of apoptosis, p53 mutations are considered to be associated with rapid tumor growth and resistance to radiation and chemotherapy. Although in certain cancers, p53 mutations are considered a poor prognostic factor, the predictive role in astrocytic tumors is not clear. Immunohistochemical studies have shown conflicting results, probably because this technique fails to provide a reliable p53 gene status. Mutation analyses have shown the association between p53 mutations and shorter survival of high-grade gliomas only in pediatric patients, but not in adults. This may suggest that p53 mutations have a relatively lower impact on the survival of malignant astrocytomas than other gene alterations, which pediatric tumors rarely harbor.
 ...
PMID:Are p53 mutations and p53 overexpression prognostic factors for astrocytic tumors? 973 40

Development of gene therapy technologies is approaching clinical realization for the treatment of neoplastic diseases. The use of tumor suppressor genes has been one useful strategy in gene therapy. Modifications and development of vectors as well as increased knowledge of the anti-tumor mechanisms of the p53 will play a significant role in the further advancement of this therapy. Currently, several laboratories have demonstrated that intratumoral injection of a virus carrying the p53 gene decreases tumor size in pre-clinical and clinical studies. Our lab has focused on a tumor-bearing mouse model in which intravenous delivery of liposome: p53 complexes decreases tumor growth. Although a high transfection efficiency of the tumor was thought to be necessary for gene therapy to exhibit anti-tumor activity with tumor suppressor genes, marked inhibition of the tumor occurs even with a low transfection efficiency. p53 may exhibit its bystander anti-tumor effect, at least in part, through an antiangiogenic effect. We believe that understanding the mechanism by which the p53 tumor suppressor gene inhibits tumor growth will lead to improvement in cancer therapy.
 ...
PMID:Systemic gene therapy with p53 inhibits breast cancer: recent advances and therapeutic implications. 974 May 51

A high proportion of tumors arise due to mutation of the p53 tumor suppressor protein. A p53 hotspot mutation at amino acid position 273 from R to H, flanking a peptide epitope that spans residues 264-272, renders cells resistant to killing by human histocompatibility leukocyte antigen (HLA)-A*0201-restricted cytotoxic T lymphocytes (CTLs) specific for this epitope. Acquisition of the R to H mutation at residue 273 of the human p53 protein promotes tumor growth in vivo by selective escape from recognition by p53.264-272 peptide-specific CTLs. Synthetic 27-mer p53 polypeptides covering the antigenic nonamer region 264-272 of p53 were used as proteasome substrates to investigate whether the R to H mutation at the P1' position of the COOH terminus of the epitope affects proteasome-mediated processing of the protein. Analysis of the generated products by tandem mass spectrometry and the kinetics of polypeptide processing in conjunction with CTL assays demonstrate that the R to H mutation alters proteasomal processing of the p53 protein by inhibiting proteolytic cleavage between residues 272 and 273. This prevents the release of the natural CTL epitope that spans flanking residues 264-272 as well as a putative precursor peptide. These results demonstrate that mutation of p53 not only leads to malignant transformation but may also, in some instances, affect immune surveillance and should be considered in the design of cancer vaccines.
 ...
PMID:The sequence alteration associated with a mutational hotspot in p53 protects cells from lysis by cytotoxic T lymphocytes specific for a flanking peptide epitope. 974 20

Gene therapy with the tumor suppressor gene p53 induces cancer cell apoptosis in vitro and in vivo and inhibits tumor growth in nude mice. We hypothesized that, in addition to cancer cell apoptosis, a replication-deficient adenovirus vector which carries the cDNA for human wild-type p53 (AdCMV.p53) may also modulate endothelial cell function and inhibit angiogenesis. Human umbilical vein endothelial cells (HUVEC) were infected at different multiplicities of infection (MOI) with either AdCMV.p53, the control vector AdCMV.null or were not infected. Western blot analysis showed p53 overexpression up to 7 days after infection with AdCMV.p53. HUVEC proliferation was either not affected (20 and 50 MOI) or inhibited to comparable levels (100 MOI; P < 0.05) in AdCMV.p53- and AdCMV.null-infected versus uninfected cells. HUVEC differentiation into capillary-like structures on reconstituted basement membrane proteins (Matrigel) was assessed 48 h after infection (100 MOI). After 18 h on Matrigel the capillary-like network formed by AdCMV.p53-infected HUVEC was less extensive than that formed by both AdCMV.null-infected and uninfected control cells (P < 0.05 versus either control). In contrast, conditioned medium from AdCMV.p53-infected HUVEC did not modulate endothelial cell differentiation on Matrigel. The effect of AdCMV.p53 on angiogenesis in vivo was assessed by injecting this vector subcutaneously in mice; 3 days later Matrigel containing basic fibroblast growth factor (bFGF) was injected at the same site. In other experiments AdCMV.p53 was injected simultaneously with an Ad vector coding for vascular endothelial growth factor (AdCMV.VEGF165) into the rat perirenal fat tissue. AdCMV.p53 significantly inhibited neovascularization induced by bFGF within the Matrigel plugs (P < 0.05) or by AdCMV.VEGF165 in the fat tissue (P < 0.05). Thus, the anti-angiogenic effect of Ad-mediated wild-type p53 overexpression may contribute to the ability of this viral vector to inhibit tumor growth.
 ...
PMID:Adenovirus-mediated wild-type p53 overexpression inhibits endothelial cell differentiation in vitro and angiogenesis in vivo. 974 54

Anaplastic thyroid carcinomas very often harbor the mutations in the tumor suppressor gene p53. We have previously shown that wild-type (wt) p53 gene introduction led to cell growth arrest, but not apoptosis, in p53-null anaplastic thyroid carcinoma cells. The present studies were designed to evaluate other therapeutic effects of wt-p53 gene introduction on p53-null thyroid carcinoma cells, as chemo- and radiosensitization and inhibition of angiogenesis have also been described recently as additional therapeutic advantages of wt-p53 gene introduction in tumor cells with p53 mutations. A p53-null anaplastic thyroid carcinoma cell line, FRO, and a FRO subline stably expressing a temperature-sensitive (ts) mutant of p53 (p53Val138), tsFRO, were used. ts-p53 functions as mutant and wt at nonpermissive (37 C) and permissive (32 C) temperatures, respectively. tsFRO showed a prolonged cell doubling time compared to parental FRO when cultured at 32 C, but the cell growth rate was similar between FRO and tsFRO at 37 C. The cytotoxic and clonogenic assays demonstrated that although the sensitivity to three different anticancer agents (cisplatin, 5-fluorocytosine, and doxorubicin) was unaltered, radiosensitivity was enhanced in tsFRO compared to FRO at 32 C. Unexpectedly, in studies on angiogenesis, expression levels of vascular endothelial growth factor (an angiogenic factor) messenger ribonucleic acid were similar between FRO and tsFRO, and thrombospondin-1 (an antiangiogenic factor) messenger ribonucleic acid and protein levels were about 2.5-fold lower in tsFRO than FRO at 32 C, although any difference could not be detected in their ability to inhibit in vitro angiogenesis with the culture medium conditioned by tsFRO and FRO at 32 C. These results suggest that p53-defective thyroid carcinomas may benefit from the combination of p53 gene therapy and radiotherapy. However, further study will be necessary to clarify the pathological significance of thrombospondin-1 in angiogenesis and thyroid tumor growth.
 ...
PMID:Therapeutic usefulness of wild-type p53 gene introduction in a p53-null anaplastic thyroid carcinoma cell line. 976 82

Apoptosis induced by the p53 tumor suppressor can attenuate cancer growth in preclinical animal models. Inactivation of the pRb proteins in mouse brain epithelium by the T121 oncogene induces aberrant proliferation and p53-dependent apoptosis. p53 inactivation causes aggressive tumor growth due to an 85% reduction in apoptosis. Here, we show that E2F1 signals p53-dependent apoptosis since E2F1 deficiency causes an 80% apoptosis reduction. E2F1 acts upstream of p53 since transcriptional activation of p53 target genes is also impaired. Yet, E2F1 deficiency does not accelerate tumor growth. Unlike normal cells, tumor cell proliferation is impaired without E2F1, counterbalancing the effect of apoptosis reduction. These studies may explain the apparent paradox that E2F1 can act as both an oncogene and a tumor suppressor in experimental systems.
 ...
PMID:Key roles for E2F1 in signaling p53-dependent apoptosis and in cell division within developing tumors. 977 67


<< Previous 1 2 3 4 5 6 7 8 9 10