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)

Neoplastic transformation occurs in all glial cell types of the human nervous system, producing a wide variety of clinico-pathological entities and morphological variants. Astrocytomas are most common and span an unusually wide spectrum, ranging from the slowly growing juvenile pilocytic astrocytoma to the highly malignant glioblastoma multiforme. Diffusely infiltrating astrocytomas of the cerebral hemispheres show an inherent tendency for progression towards a more malignant phenotype. This change is morphologically categorized in histologic grading schemes (e.g., WHO Grade II to IV) and is associated with the sequential acquisition of genetic alterations, including mutations in the p53 and homozygous deletions of the p16 tumour suppressor genes. Loss of heterozygosity on chromosomes 10 and 19q as well as amplification of the EGF receptor are largely restricted to malignant gliomas and thus considered late events in astrocytoma progression. Gliomas often show phenotypic expression of different glial cell lineages (e.g., oligoastrocytoma). Recent studies suggest that the occurrence of mixed gliomas is not indicative of a polyclonal origin but rather reflects altered gene expression, leading to a change in the balance of growth factors influencing glioma differentiation.
 ...
PMID:Histopathology, classification, and grading of gliomas. 858 58

Abnormalities of the p53 gene are the most common molecular change in human cancer. In the central nervous system, mutant p53 gene is frequently identified in the tumors with astrocytic differentiation. To investigate the relation between histologic subtypes and p53 protein overexpression, we examined 81 cases of astrocytic neoplasms (24 benign astrocytoma, 28 anaplastic astrocytoma and 29 glioblastoma multiforme) using the standard immunohistochemical method. All were formalin-fixed and paraffin-embedded tissue. The p53 immunoreactivity was found in 4/24 benign astrocytoma, 18/28 anaplastic astrocytoma, 22/29 glioblastoma multiforme. The degree of immunoreactivity closely correlated with histologic subtypes (p < 0.001). Overall p53 protein expression was most frequently detected in glioblastoma multiforme, but strong immunoreactivity (3+) was more frequently found in the anaplastic astrocytoma than in glioblastoma multiforme. Although the frequency of p53 protein expression is low, 4 benign astrocytoma showed distinct nuclear staining. In conclusion the malignant progression of astrocytic neoplasms may be associated with increasing expression of p53 protein.
 ...
PMID:p53 protein overexpression in astrocytic neoplasms. 859 54

Recent molecular biological studies have shown evidence for a distinct pathogenesis of pilocytic astrocytomas based on alterations other than mutations of the tumor suppressor gene p53. To prove these data, the authors screened a series of 42 astrocytic human brain tumors with a relatively high proportion (16.6%) of the pilocytic variant for the presence of p53 mutations, using the polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) analysis, followed by DNA sequencing. Mutations were found in one of seven (14.3%) pilocytic astrocytomas, in one of 18 (5.6%) low grade astrocytomas, and in one of four (25%) anaplastic astrocytomas, but in none of 13 glioblastomas. Sites of missense mutations were in exon 8 (codons 281 and 282), and exon 5 (codon 151). Silent mutation was found in exon 9 (codon 324), which was related to pilocytic astrocytoma. This is, to the authors' knowledge, the first report that shows a p53 mutation in pilocytic astrocytomas. However, the p53 mutation was only found in one of seven tumors of this entity and was a silent mutation, which does not lead to change of amino acids. Thus, the significance of this alteration for the development of this special tumor type seems to be low. Nevertheless, it may be a sign of genetic instability and is thus suggested to be of certain pathogenetic relevance. The p53 findings concerning the other tumors are in accordance with the view of p53 gene mutations to be early events in astrocytoma formation.
 ...
PMID:p53 gene mutations in human astrocytic brain tumors including pilocytic astrocytomas. 866 69

Gliofibromas are rarely encountered astrocytic neoplasms characterized by an admixture of astrocytic and fibroblastic cell components. The exact nature of these rare tumors are still a matter of considerable debate. This article reports a case of gliofibroma occurring in a 3-month-old boy. The astrocytic component of the tumor stained diffusely positive for glial fibrillary acidic protein (GFAP) and S-100 protein. Prominent reticulin staining was observed within the fibroblastic component of the tumor. The MIB1 labeling index (positive number of tumor cells divided by total tumor cells counted X 100) was low (0.9), supporting the general slow growth of these tumors. Immunohistochemical staining with antibody against p53 protein was negative. Gliofibromas seem to be a low-grade variant of an astrocytoma that shares many features with other desmoplastic astrocytic neoplasms (desmoplastic infantile astrocytoma, desmoplastic infantile ganglioglioma) including a generally favorable prognosis.
 ...
PMID:Gliofibroma: a distinct entity or a subtype of desmoplastic astrocytoma? 866 74

We describe molecular and clinical findings in an immunocompetent patient with an oligoastrocytoma and the concomitant presence of the human papovavirus, JC virus (JCV), which is the etiologic agent of the subacute, debilitating demyelinating disease, progressive multifocal leukoencephalopathy. Histologic review revealed a glial neoplasm consisting primarily of a moderately cellular oligodendroglioma with distinct areas of a fibrillary astrocytoma. Immunohistochemical analysis revealed nuclear staining of tumor cells with antibodies against the viral oncoprotein [tumor antigen (T antigen)], the proliferation marker (Ki67), and the cellular proliferation regulator (p53). Using primers specific to the JCV control region, PCR yielded amplified DNA that was identical to the control region of the Mad-4 strain of the virus. PCR analysis demonstrated the presence of the genome for the viral oncoprotein, T antigen, and results from primer extension studies revealed synthesis of the viral early RNA for T antigen in the tumor tissues. The presence of viral T antigen in the tumor tissue was further demonstrated by immunoblot assay. To our knowledge, this is the first report of the presence of JCV DNA, RNA, and T antigen in tissue in which viral T antigen is localized to tumor cell nuclei and suggests the possible association of JCV with some glial neoplasms.
 ...
PMID:Detection of JC virus DNA sequence and expression of the viral oncoprotein, tumor antigen, in brain of immunocompetent patient with oligoastrocytoma. 869 97

Tumor growth depends on cell division and cell death. To investigate the role of apoptosis in tumor cell death, we examined 83 cases of glial tumors using in situ nonradioactive tailing of DNA breaks. In addition, since p53 protein may participate in the regulation of apoptosis in glioblastoma, we compared the apoptosis ratio (AR) with the labeling index (LI) of p53 protein immunopositivity. The AR in glial tumor parenchyma ranged from 0 to 1.4%: mean AR +/- standard deviation was 0.4 +/- 0.4% (range, 0-1.4) for glioblastoma, 0.3 +/- 0.3% (range, 0.01-0.83) for anaplastic astrocytoma, 0.1 +/- 0.1% (range, 0-0.41) for low-grade astrocytoma, 0.006 +/- 0.008% (range, 0-0.02) for pilocytic astrocytoma, 0.2 +/- 0.2% (range, 0-0.62) for oligodendroglioma and 0.003 +/- 0.004% (range, 0-0.01) for ependymoma. ARs were significantly higher in higher-grade astrocytic tumors than in lower-grade tumors (Mann-Whitney U test: P = 0.0003), although wide variability in each group resulted in overlapping between the groups. p53 protein immunopositivity (more than 25% of nuclei) was found in 15 of 32 glioblastoma cases, while in the remaining 17 none or only a low percentage (up to 6%) of the nuclei were positive. In p53 protein-positive cases mean AR (0.51 +/- 0.47%) was not significantly higher than that in p53 protein-negative cases (0.22 +/- 0.23%; P = 0.1681).
 ...
PMID:Apoptosis in glial tumors as determined by in situ nonradioactive labeling of DNA breaks. 877 55

Genomic alterations associated with glioma progression were determined by comparative genomic hybridization (CGH) 30 tumors from 15 patients with primary gliomas of World Health Organization (WHO) grade II that on recurrence showed progression to malignant gliomas of WHO grades III or IV (five cases of astrocytoma grade II (A II) to grade III (AA III), five cases of A II to glioblastoma multiforme grade IV (GBM) and five cases of oligodendroglioma grade II (O II) to grade III (AO III)). All tumors were additionally screened for p53 mutations by single strand conformational polymorphism and heteroduplex analysis of exons 5-8, followed by direct sequencing. Mutations of p53 were found in the primary and recurrent tumors of all cases of A II progressing to GBM and three of five cases of A II recurring as AA III. Alterations identified by CGH in more than one primary A II included losses on Xp (3/10) and 5p (2/10), gains on 8q and 19p (2/10 each), and gain/amplification on 12p (2/10). Common progression associated changes found in AA III or GBM were losses on 4q, 9p, 10q, 11p, 13q (4/10 each) and gains on 1q, 6p, 20q (2/10 each). The most frequent amplification site was located on 12p13 (1/10 A II, 3/5 AA III, 1/5 GBM). Other amplified chromosomal regions were 13q32-q34 (1/10 AII, 2/5 GBM), 7q31-qter (1/5 AA III, 1/5 GBM), 12q22-qter and 18p (1/5 AA III). In contrast to the astrocytic gliomas, only one of five oligodendroglial cases showed a p53 mutation. Genetic abnormalities identified by CGH to occur more than once were restricted to four chromosomes (1, 4, 9 and 19). Our results provide a comprehensive overview of the genomic alterations associated with the progression of individual gliomas and substantiate the hypothesis that glioma progression is associated with a cumulative acquisition of multiple genetic changes.
 ...
PMID:Characterization of genomic alterations associated with glioma progression by comparative genomic hybridization. 880 88

To investigate the molecular mechanisms of tuberous sclerosis (TSC) histopathologic lesions, we have tested for loss of heterozygosity the two TSC loci (TSC1 and TSC2) and seven tumor suppressor gene-containing regions (TP53, NF1, NF2, BRCA1, APC, VHL, and MLM) in 20 hamartomas from 18 TSC patients. Overall, eight angiomyolipomas, eight giant cell astrocytomas, one cortical tuber, and three rhabdomyomas were analyzed. Loss of heterozygosity at either TSC locus was found in a large fraction of the informative patients, both sporadic (7/14) and familial (1/4). Interestingly, a statistically significant preponderance of loss of heterozygosity at TSC2 was observed in the sporadic group (P < 0.01). Among the possible explanations considered, the bias in the selection for TSC patients with the most severe organ impairment seems particularly appealing. According to this view, a TSC2 defect might confer a greater risk for early kidney failure or, possibly, a more rapid growth of a giant cell astrocytoma. None of the seven antioncogenes tested showed loss of heterozygosity, indicating that the loss of either TSC gene product may be sufficient to promote hamartomatous cell growth. Finally, the observation of loss of heterozygosity at different markers in an astrocytoma and in an angiomyolipoma from the same patient might suggest the multifocal origin of the second-hit mutation.
 ...
PMID:Apparent preferential loss of heterozygosity at TSC2 over TSC1 chromosomal region in tuberous sclerosis hamartomas. 882 21

The genes involved in the genesis and progression of adult astrocytic tumors have been an area of considerable investigation. The tumor suppressor gene, p53, has been implicated, as has the epidermal growth factor receptor gene. Additional currently unidentified genes lie on chromosomes 10 and 19. Interestingly, work on pediatric astrocytomas suggests that the genes involved are different. p53 is rarely mutated in pediatric tumors, the epidermal growth factor receptor gene is rarely amplified or mutated, and chromosome 10 deletions are rare. The only pediatric tumor that seems to mimic the findings in adult tumors is brainstem glioma, perhaps explaining the uniformly grim prognosis in this type of tumor. In the pilocytic astrocytoma of childhood, mutations in the neurofibromatosis type I gene have been implicated in tumor development. In this review, the oncogenesis of pediatric gliomas is discussed and compared and contrasted to what is known about tumors.
 ...
PMID:Molecular biology of pediatric gliomas. 883 57

Pleomorphic xanthoastrocytoma (PXA) is a low-grade glioma that may recur as a malignant diffuse astrocytoma such as glioblastoma (GBM). While the molecular genetic basis of diffuse astrocytomas has been studied extensively, PXAs have not been analyzed in detail. We, therefore analyzed DNA from archival primary and recurrent PXAs from eight patients (three grade II PXAs without recurrence, one grade II PXA with recurrence as grade II PXA, two grade II PXAs with progression to GBM, and two grade III anaplastic PXAs with recurrence as grade III anaplastic PXA or GBM) for genetic changes associated with diffuse astrocytomas. Single-strand conformation polymorphism analysis of p53 exons 5-8 revealed migration shifts in two cases, one primary PXA without recurrence and one recurrent grade II PXA in which the primary tumor did not show a shift. DNA sequencing showed two missense mutations in codons 220 (exon 6) and 292 (exon 8), respectively, mutations which have not been previously noted in astrocytomas. Differential polymerase chain reaction analysis demonstrated epidermal growth factor receptor gene amplification in only one tumor, a GBM without allelic loss of chromosome 10 that was the second GBM recurrence of an initial grade II PXA. Loss of heterozygosity studies on tumors from five patients, using three microsatellite polymorphisms on chromosome 10q and three on chromosome 19q, did not disclose allelic loss in any recurrent tumor. These findings suggest that the genetic events that underlie PXA formation and progression may differ significantly from those involved in diffuse astrocytoma tumorigenesis.
 ...
PMID:Molecular genetic alterations in pleomorphic xanthoastrocytoma. 883 42


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