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)

We investigated the mechanism of radiation induction of murine thymic lymphomas by studying the characteristics of primary x-ray-induced thymic lymphoma (PXTL) cell lines and of their oncogene-induced, progressed progeny. It is widely thought that proto-oncogene alterations are associated with the induction of murine lymphomas; however, few, if any primary murine radiation-induced lymphomas possess (proto-)oncogene alterations. Independently derived cell lines grown directly (i.e., without in vivo transplantation) from thymic lymphomas of irradiated C57BL/6 mice possess the properties of immortalized pre-T cells and lack many of the characteristics of "tumor cells". PXTL cells are poorly tumorigenic upon transplantation, do not clone in methylcellulose cultures, are growth factor dependent and autocrine, and lack consistent chromosome and oncogene abnormalities. However, the thymic lymphomas are malignant and cause the death of each afflicted mouse. PXTL cells expressed two immunologically distinct forms of the tumor suppressor protein p53 that have moderately increased stability (t1/2 = 1 h) when compared with p53 of normal splenic T lymphocytes. Early PXTL cells could progress in vitro to a fully tumorigenic phenotype after infection with retroviruses encoding the c-myc and v-ras oncogenes. Progressed T-lymphoma cells acquired growth factor independence, a highly transplantable and tumorigenic phenotype, and the ability to quantitatively clone in methylcellulose cultures. Progressed lymphoma cells coordinately downregulated the expression of five T-cell differentiation markers, upregulated the expression of CD44 (Pgp-1), and harbored vastly elevated levels of two immunologically distinct forms of p53. Our results suggest that the early thymic lymphomas consist of differentiation-inhibited, immortal pre-T cells that are precursors to progressed, fully tumorigenic T-lymphoma cells.
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PMID:Association of induction of a fully tumorigenic phenotype in murine radiation-induced T-lymphoma cells with loss of differentiation antigens, gain of CD44, and alterations in p53 protein levels. 158 48

Myelodysplastic syndromes originate from a pluripotent stem cell. This view, previously suggested by G-6-PD and cytogenetic investigations, has been established unequivocally by X-chromosome inactivation analysis based on DNA polymorphisms and by studies of mutated oncogenes. Two genomic alterations associated with MDS have been analyzed in more detail. Activation of the RAS oncogenes, preferentially N-RAS, is demonstrated in approximately 35% of MDS patients. Mutations in the FMS gene, encoding the CSF-1 receptor, are found in 16% of cases. Interestingly, RAS and FMS mutations are predominantly observed in disorders of myelomonoctic differentiation, i.e., the CMML subtype in MDS and the AML FAB type M4. Moreover, homozygous deletion of the FMS gene may be an important event in the genesis of the MDS variant 5q- syndrome. Preliminary data indicate that defects in tumor-suppressor genes, namely p53, may also contribute to the development of MDS. Different lines of evidence suggest that clinical preleukemia is preceded by a phase in which genetic alterations accumulate without any hematologic change. Cases in point are the detection of RAS and FMS mutations in healthy individuals who had been treated in the past with cytotoxic therapy for lymphoma, the frequent observation of clonal remission in AML patients, or the identification of oncogene mutations in healthy individuals without even a history of malignancy or chemotherapy. Possibly, either germline mutations of oncogenes or tumor-suppressor genes and the process of genomic imprinting may constitute additional factors that predispose hematopoietic stem cells to malignant transformation. Limited as they are, the currently available data suggest that accumulation of genomic lesions, rather than their precise order of development with respect to one another, characterize the multistep process of leukemogenesis in which MDS already represent more advanced stages. The prognostic significance of oncogene mutations in MDS patients is controversially discussed. This issue awaits prospective analyses taking into account the influence of treatment modalities. However, the clinical relevance of molecularly defined parameters has already been established for their use as clonal markers in determining the mode of action and efficiency of different therapeutic approaches.
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PMID:Molecular genetic aspects of myelodysplastic syndromes. 161 6

Chronically immunosuppressed individuals are susceptible to lymphoreticular tumors. Up to 15% of patients with congenital deficiencies such as ataxia=telangiectasia may develop malignancies, mainly high-grade B cell non=Hodgkin's lymphomas (NHLs). AIDS lymphomas are comprised of NHLs including Burkitt's lymphoma (BL) and primary cerebral lymphomas (PCLs). Almost 3% of all AIDS patients (2824 of 97,258 cases) developed NHL. Epstein-Barr virus (EBV) as a co-factor in AIDS lymphomagenesis has been studied: in 12 cases of 24 AIDS lymphomas EBV by DNA in situ hybridization was found. In an analysis of 6 primary cerebral lymphomas, .5 were positive for EBV DNA by Southern blotting. In Burkitt's lymphoma the characteristic genetic alteration affects the c-myc oncogene. In 1/3 of BL p53 mutations were found but none in the 43 NHLs suggesting that p53 mutations and c-myc activation act synergistically in the pathogenesis of these tumors. Cytotoxic agents dideoxyinosine, dideoxycytosine, and zidovudine may cause secondary neoplasia. 8 of 55 AIDS patients under zidovudine treatment developed high-grade lymphoma 23.8 months subsequently; recently doses were reduced. PCL was found in 21 of 90 patients. A 5.2 months survival was associated with combined treatment with cyclophosphamide, Oncovin (vincristine), methotrexate, etoposide, and cytosine arabinoside compared with 11.3 months with chemotherapy. Colony-stimulating factors (CSFs) alleviate drug-induced myelotoxicity and zidovudine-induced neutropenia, however, l8 of 11 patients receiving granulocyte-macrophage CSF developed hematological toxicity. Interleukine-2 produced by T-helper cells enhancing tumor cells cytotoxicity has been used in AIDS-associated cryptosporidial diarrhea and in 4 patients with AIDS lymphoma with modest response, but its stimulation of the HIV-infected substrate may increase viral proliferation.
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PMID:AIDS lymphomas. 161 63

The gene encoding p53 phosphoprotein, originally believed to be an oncogene, recently has been proposed as a candidate antioncogene (tumor-suppressor gene). Abnormalities of the p53 gene expression have been demonstrated in different human malignancies including carcinomas and sarcomas, but little information concerning p53 immunoreactivity in human lymphomas is so far available. In this study immunohistochemical staining for p53-protein was performed on frozen- and paraffin-embedded samples from patients with Hodgkin's (HD) and non-Hodgkin's lymphomas (NHL). No p53 immunoreactivity could be demonstrated in any cell type in nonneoplastic lymphoid samples, including germinal center cells in reactive lymph nodes and cortical thymocytes. On the other hand, a significant proportion of p53+ neoplastic cells was observed in 23 of 31 cases of HD and 17 of 68 cases of NHL. All positive lymphoma cases were diagnosed as high-grade or CD30+ anaplastic NHL. The demonstration of abnormal expression of p53 protein in these diseases can contribute to addressing unresolved issues regarding the origin and pathogenesis of HD and CD30+ anaplastic lymphomas.
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PMID:Immunohistochemical evidence of abnormal expression of the antioncogene-encoded p53 phosphoprotein in Hodgkin's disease and CD30+ anaplastic lymphomas. 168 Jan 18

The clinical course of lymphoma patients in whom rearrangements or deletions of the short arm of chromosome 17 (17p) were evident by cytogenetics was rapidly progressive with a short survival. The gene for the protein designated p53 resides in 17p. We studied four lymphoma cell lines derived from human tumours, and 25 tumour samples of patients with lymphomas, for any evidence of p53 genomic changes by Southern blot technique. The four cell lines and four of the 25 tumour samples showed numerical changes of chromosome 17 or structural abnormalities of 17p (translocations or deletions). Allelic loss of the p53 gene was found in two of the four cell lines, and one of these in addition showed a rearrangement of the 3' end of the gene. Of the four tumours known to have chromosome 17 abnormality, one specimen showed allelic loss of the p53 gene. None of the remaining tumour samples showed any significant change. These studies suggest that acquisition of changes in the short arm of chromosome 17, which may be interrelated with the p53 gene, may carry a poor prognosis in patients with non-Hodgkin's lymphoma.
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PMID:Chromosome 17- and p53 changes in lymphoma. 177 79

Programmed cell death is a physiological, energy-consuming mechanism leading to suicide of the cell. Cell death is accomplished by the activation of endonucleases that fragment the cell's nuclear DNA. Some tumour cells remain susceptible to programmed death. These are hormone- and growth factor-dependent tumour cells. Hormone or growth factor deprivation induces signals leading to apoptosis. Other tumours gain strong resistance to apoptosis. One of the normal functions of the bcl-2 gene is to provide longevity to memory B cells. When this gene becomes translocated in follicular B cell lymphomas, it renders lymphoma cells resistant to apoptosis. Latent membrane protein encoded by an EBV gene, either by itself or by amplifying bcl-2, enables tumour cells (nasopharyngeal carcinoma; Reed-Sternberg cell of Hodgkin's disease) to resist apoptotic death. Loss of antioncogene p53 provides for resistance against programmed cell death. Breakdown of resistance to apoptosis in tumour cells can be achieved by oncolytic viruses; generation of lymphotoxin and tumour necrosis factor; monoclonal antibodies; transfection with plasmid vectors carrying p53; gamma irradiation; and certain chemotherapeutic agents.
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PMID:Programmed cell death (apoptosis): its virological and immunological connections (a review). 181 29

Oncogene dosage and expression were studied in 16 testicular neoplasms, 14 of germ cell and two of non-germ cell origin. In comparison with normal DNA, tumour DNA of a total of eight patients (seven with germ cell neoplasm and one with testicular lymphoma) showed increased dosages of KRAS2, PDGFA, EGFR, MET and PDGFB. The most frequent (occurring in six tumours) and prominent (up to 3-4-fold) increases were detected in the dosages of KRAS2 (on chromosome 12p) and PDGFA (chromosome 7p), relative to a reference locus from chromosome 2. Importantly, there was a similar increase in 12p dosage in general in these tumours, suggesting the presence of the characteristic isochromosome 12p marker. On the contrary, possible 7p polysomy (assessed by molecular methods) did not explain the PDGFA (or EGFR) changes in all cases. NRAS, MYCN, CSFIR, MYB, MYC, ABL, HRASI, TP53, and ERBB2 did not reveal any consistent alterations in tumour DNA. In RNA dot blot assays the expression of KRAS2, PDGFA, EGFR, or MYC was generally not increased in the tumour samples when compared to that in normal testicular tissue of the same patients although there was interindividual variation in mRNA levels. It thus appears that while oncogene dosage changes occur in a proportion of testis cancers, they are often part of changes in large chromosomal regions or whole arms and are seldom accompanied by altered expression.
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PMID:Oncogenes in human testicular cancer: DNA and RNA studies. 182 52

Twelve long-term cell lines were established from peripheral blood mononuclear cells (PBMC) or cerebrospinal fluid cells of patients with human T lymphotropic virus type I (HTLV-1) seropositive tropical spastic paraparesis (TSP) originating from the French West Indies, French Guyana or the Central African Republic. Most of these long-term interleukin-2-dependent cell lines exhibited a pattern characteristic of CD4(+)-activated T cells with high expression of CD2, CD3 and CD4 antigens, associated with a strong density of TAC and DR molecules. Nevertheless, in five cases CD8 expression was present at a significant level. HTLV-I antigens were never detected in uncultured PBMC, but they were expressed in a few cells after short-term culture and after 4 months the majority of the cells were HTLV-I positive, as demonstrated by indirect immunofluorescence (IF) using polyclonal or monoclonal anti-p19 and anti-p24 antibodies. Low and variable levels of reverse transcriptase activity were detected in supernatant fluids of these cell lines only after 4 months of culture, when at least 50% of the cells exhibited HTLV-I antigens by IF. However, numerous type C HTLV-I-like viral particles were detected, mostly in the extracellular spaces, with rare budding particles. Similar findings were found in three T cell lines derived from West Indian and African patients with adult T-cell leukaemia/lymphoma (ATLL). Differences in high Mr polypeptides were detected by Western blot in cell lysates when comparing TSP- or ATLL-derived T cell lines. Thus a signal of 62K was easily detectable in all the TSP lines, but not in the ATLL lines. In all cell lines bands corresponding to p53, p24 and p19 viral core polypeptides were present, as was the env gene-coded protein p46.
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PMID:Cell surface phenotype and human T lymphotropic virus type 1 antigen expression in 12 T cell lines derived from peripheral blood and cerebrospinal fluid of West Indian, Guyanese and African patients with tropical spastic paraparesis. 230 64

Epstein-Barr virus and the C3d fragment of the third component of complement are specific extracellular ligands for complement receptor type 2 (CR2). However, intracellular proteins that react specifically with CR2 and are involved in post-membrane signals remain unknown. We recently prepared polyclonal anti-idiotypic anti-CR2 antibodies (Ab2) by using the highly purified CR2 molecule as original immunogen. We showed that Ab2 contained anti-idiotypic specificities that mimicked extracellular domains of CR2 and detected two distinct binding sites on CR2 for its specific extracellular ligands, Epstein-Barr virus and C3d. We postulated that Ab2 might also contain specificities that could mimic intracellular domains of CR2. Here we report that Ab2, which did not react with Raji B-lymphoma cell surface components, detected specifically, among all components solubilized from Raji cell membranes, a single intracellular membrane protein of apparent molecular mass of 53 kDa. This protein was identified as the p53 cellular antioncogene-encoded membrane phosphoprotein by analyzing its antigenic properties with Pab1801, a monoclonal anti-p53 antibody, and by comparing its biochemical properties with those of p53. Additionally, solubilized and purified CR2 bound to solubilized p53 immobilized on Pab1801-Sepharose. p53, like CR2, was localized only in purified plasma membranes and nuclei of Raji cells. These data suggest strongly that p53, a cellular antioncogene-encoded phosphoprotein, reacted specifically with CR2 in Raji membranes. This interaction may represent one of the important steps through which CR2 could be involved in human B-lymphocyte proliferation and transformation.
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PMID:Epstein-Barr virus/complement fragment C3d receptor (CR2) reacts with p53, a cellular antioncogene-encoded membrane phosphoprotein: detection by polyclonal anti-idiotypic anti-CR2 antibodies. 255 14

We have investigated the mechanism of action of IL 1 on T cell activation. For this purpose, we analyzed the content of specific messenger RNA for lymphokines and other genes that are associated with T cell activation in the murine IL 1-dependent T cell lymphoma LBRM33-1A5. Using cloned genes for IL 2, IL 3, TGF-beta, TY5, IL 2 receptor, Ly-1, c-myc, and p53 as probes in the S1 nuclease protection assay, we compared the amount of specific transcripts among total RNA prepared from unstimulated cells, IL 1 alpha or PHA-stimulated cells, and PHA plus IL 1 alpha-stimulated cells. IL 1 alpha augmented the PHA-induced accumulation of IL 2 mRNA with a magnitude comparable to the amount of IL 2 produced, suggesting that IL 1 alpha modulates IL 2 gene expression at the RNA level. Similar results were obtained with IL 3. We also observed that Ly-1 mRNA appears after PHA treatment and its accumulation was augmented by IL 1 alpha addition. On the basis of the effects of IL 1 alpha and/or PHA treatments on gene expression, we classified these genes into four groups. In all cases, IL 1 alpha seemed to affect mRNA levels quantitatively. These observations support previously described characteristics of this cytokine as a co-stimulator of T cell activation.
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PMID:Interleukin 1 modulates messenger RNA levels of lymphokines and of other molecules associated with T cell activation in the T cell lymphoma LBRM33-1A5. 349 73


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