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)

Astrocytic brain tumors are the most frequent human gliomas and they include a wide range of neoplasms with distinct clinical, histopathologic, and genetic features. Diffuse astrocytomas are predominantly located in the cerebral hemispheres of adults and have an inherent tendency to progress to anaplastic astrocytoma and (secondary) glioblastoma. The majority of glioblastomas develop de novo (primary glioblastomas), without an identifiable less-malignant precursor lesion. These subtypes of glioblastoma evolve through different genetic pathways, affect patients at different ages, and are likely to differ in their responses to therapy. Primary glioblastomas occur in older patients and typically show epidermal growth factor receptor (EGFR) overexpression, PTEN mutations, p16 deletions, and, less frequently, MDM2 amplification. Secondary glioblastomas develop in younger patients and often contain TP53 mutations as their earliest detectable alteration. Morphologic variants of glioblastoma were shown to have intermediate clinical and genetic profiles. The giant cell glioblastoma clinically and genetically occupies a hybrid position between primary (de novo) and secondary glioblastomas. Gliosarcomas show identical gene mutations in the gliomatous and sarcomatous tumor components, which strongly supports the concept that there is a monoclonal origin for gliosarcomas and an evolution of the sarcomatous component due to aberrant mesenchymal differentiation in a highly malignant astrocytic neoplasm.
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PMID:Phenotype vs genotype in the evolution of astrocytic brain tumors. 1066 4

In recent years, there have been great advances in our understanding of the genetic events and the molecular biology of human brain gliomas. Cytogenetic information has suggested that a pattern of non-random abnormalities involving numerical deviations such as the gain, partial deletion, or total loss of chromosomes as well as translocations and structural rearrangements of certain chromosome lesions are characteristic features for some tumors. In addition, the somatic activation of cellular oncogenes and inactivation of tumor suppressor genes represent important genetic alterations leading to progressive disorder of normal cellular growth control mechanisms. This review describes the abnormal chromosomal and molecular abnormalities that occur during formation of brain tumors of astrocytic origin, particularly fibrillary astrocytic neoplasms. The most frequent genetic alterations include inactivation of the p53, p16, Rb and PTEN genes, and overexpression of the CDK4, EGFR and VEGF genes. Other less well defined abnormalities include aberrations in chromosomes 1, 9, 10, 11, 19 and 22.
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PMID:Cytogenetic and molecular abnormalities in astrocytic gliomas (Review). 1067 94

The recently discovered tumor suppressor gene PTEN has been found mutated in many types of advanced tumors. When introduced into tumor cells that lack the wild-type allele of the gene, PTEN was able to suppress the growth of these cells. Here, we have analyzed how PTEN might alter cell cycle-regulatory controls to achieve this growth-inhibitory effect. We found that overexpression of PTEN stimulates the synthesis of three inhibitors of cyclin-dependent kinases, p21WAF1, p27KIP1, and p57KIP2. This effect is very specific, as the expression of other components of the cell cycle engine, various cyclins and cyclin-dependent kinases, is not affected. For p21WAF1 we show that this induction is due to the p53-independent transcriptional activation of its promoter. In addition, increased expression of PTEN rendered the cells more sensitive to apoptotic cell death. Therefore, our data suggest a two-fold mechanism of growth inhibition by PTEN: one that acts via the increased expression of CKIs such as p21WAF1, and another that augments the cellular propensity for apoptotic cell death.
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PMID:Transcriptional activation of p21WAF1 by PTEN/MMAC1 tumor suppressor. 1072 33

Permanent glioma cell lines are invaluable tools in understanding the biology of glioblastomas. The present study reports the establishment of a clonal human cell line, GBM6840, derived from a biopsy of paediatric cerebellar glioblastoma multiforme. GBM6840 had a doubling time of 32 h and grew as a monolayer of large round cells that retained immunopositivity for glial fibrillary acidic protein and vimentin. Karyotypic analysis revealed a modal chromosome number of 68 and polysomies of chromosomes 3, 5 and 20, as well as the presence of 3-4 marker chromosomes. GBM6840 also showed anchorage-independent growth in soft agar and tumour formation in nude mice. The p16(CDKN2A) gene was transcriptionally silenced by hypermethylation, consistent with the lack of protein expression observed in the original tumour and cultured cells. Western blot analysis revealed normal protein expression of pRb and CDK4. It appears that p16 is the major component altered in the cell cycle pathway and may confer these cells unrestrained proliferation potential. Neither EGFR gene amplification nor over-expression of the protein was detected in the cultured cells. Over-expression of the p53 protein was observed in the majority of cells, despite undetectable mutation (exons 5-8) in the gene. One allele of the PTEN gene was found to be mutated during in vitro cultivation. Telomerase activity was demonstrated in the cultured cells but not in the original tumour, supporting the hypothesis that telomerase is required for the in vitro immortalization process.
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PMID:Establishment and characterization of a human cell line from paediatric cerebellar glioblastoma multiforme. 1073 64

Historical observations have suggested that endometrial carcinomas vary in histopathologic appearance and clinical features. More recent, systematic studies have provided epidemiologic, clinicopathologic, and molecular support for these observations. Specifically, studies suggest that the most common type of endometrial carcinoma, endometrioid adenocarcinoma, develops from endometrial hyperplasia in the setting of excess estrogen exposure and usually pursues an indolent clinical course. In contrast, a minority of endometrial carcinomas, best represented by serous carcinoma, do not seem to be related to estrogenic risk factors or elevated serum hormone levels, and these tumors seem to develop from atrophic rather than hyperplastic epithelium. We have proposed that serous carcinomas develop from "endometrial intraepithelial carcinoma," a lesion representing malignant transformation of the endometrial surface epithelium. Whereas endometrioid carcinoma and endometrial hyperplasia are associated with microsatellite instability and ras and PTEN mutations, serous carcinoma and endometrial intraepithelial carcinoma are associated with p53 mutations and abnormal accumulation of p53 protein. Based on these data regarding the pathogenesis of endometrioid and serous carcinoma, we have proposed a dualistic model of endometrial carcinogenesis incorporating a "classic" estrogen-driven pathway and an "alternative" pathway seemingly unrelated to hormones. It is hoped that further studies may permit the extension and modification of this model and that these advances will lead to improved diagnosis, management, and prevention.
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PMID:Theories of endometrial carcinogenesis: a multidisciplinary approach. 1075 40

Alterations in the cell division:cell death ratio induce multiple autoimmune and transformation processes. Phosphoinositide 3-kinase (PI3K) controls cell division and cell death in vitro, but its effect on the function of the cellular immune system and on tumor formation in mammals is poorly characterized. Here we show that transgenic mice expressing in T lymphocytes an active form of PI3K derived from a thymic lymphoma, p65(PI3K), developed an infiltrating lymphoproliferative disorder and autoimmune renal disease with an increased number of T lymphocytes exhibiting a memory phenotype and reduced apoptosis. This pathology was strikingly similar to that described in mice exhibiting heterozygous loss of the tumor suppressor PTEN, a lipid and protein phosphatase. We show that overexpression of PTEN selectively blocks p65(PI3K)-induced 3T3 fibroblast transformation. Moreover, the early development of T cell lymphomas in p65(PI3K) Tg p53(-/-) mice indicated that PI3K contributes to tumor development. These observations demonstrate that constitutive activation of PI3K extends T cell survival in vivo, affects T cell homeostasis, and contributes to tumor generation, supporting a model in which selective increases in one type of PTEN substrate, the PI3K-derived lipid products, induce tumorigenesis. PI3K thus emerges as a potential target in autoimmune disease and cancer therapy.
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PMID:Increased phosphoinositide 3-kinase activity induces a lymphoproliferative disorder and contributes to tumor generation in vivo. 1078 43

Epidemiological studies suggest that some familial aggregations of glioma may be due to inherited predisposition. Many genes involved in familial cancers are frequently altered in the corresponding sporadic forms. We have investigated several genes known to be altered in sporadic gliomas for their potential contribution to familial glioma. Fifteen glioma patients with a family history of brain tumors were identified through the Mayo Clinic Department of Neurology (nine diffuse astrocytomas, two oligodendrogliomas, two mixed oligoastrocytomas, one pilocytic astrocytoma, and one pineal glioma). Eleven of the propositi had one or more first degree relative with a glioma. Lymphocyte DNA was derived from each of the patients and analyzed by polymerase chain reaction (PCR) and direct sequencing of the PTEN, p53, p16(INK4A)/p14(ARF), and CDK4 genes. In addition, fluorescence in situ hybridization (FISH) was performed on EBV-transformed lymphocytes from each affected individual to detect germline copy number of the p16(INK4A)/p14(ARF) tumor suppressor region. A p53 germline point mutation was identified in one family with some findings of Li-Fraumeni syndrome, and a hemizygous germline deletion of the p16(INK4A)/p14(ARF) tumor suppressor region was demonstrated by FISH in a family with history of both astrocytoma and melanoma. Thus, whereas germ-line mutations of PTEN, p53, p16(INK4A)/p14(ARF), and CDK4 are not common events in familial glioma, outside of familial cancer syndromes, point mutations of p53 and hemizygous deletions and other rearrangements of the p16(INK4A)/p14(ARF) tumor suppressor region may account for a subset of familial glioma cases. Collectively, these data lend genetic support to the heritable nature of some cases of glioma.
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PMID:Investigation of germline PTEN, p53, p16(INK4A)/p14(ARF), and CDK4 alterations in familial glioma. 1079 39

The medical histories of breast cancer-prone families have been described for over a century. The pattern of breast cancer occurrences in these families is most consistent with an autosomal dominant mode of inheritance. The location of a gene that could explain the pattern of transmission of the breast cancer trait in families averaging early (pre-menopausal) onset of breast cancer was reported in 1990. Since then, two genes have been identified: BRCA1 and BRCA2. Germ-line mutations in these two genes confer susceptibility to breast (female and male) and ovarian cancer, and account for a significant proportion of hereditary breast cancer in two cancer syndromes: site-specific breast cancer and the breast-ovarian cancer syndrome. Other hereditary syndromes that feature breast cancer are Li-Fraumeni syndrome, Cowden disease, and ataxia telangiectasia, whose carriers have been shown to harbor germ-line mutations in TP53, PTEN, and ATM, respectively. There may be other genetic factors that contribute to hereditary breast cancer, since not all families with multiple cases of breast cancer harbor germ-line BRCA1 or BRCA2 mutations. Host factors (such as lifestyle choices) and other genes may modulate risk of breast cancer in mutation carriers.
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PMID:Genes implicated in hereditary breast cancer syndromes. 1080 49

Alterations in the cellular genome affecting the expression or function of genes controlling cell growth and differentiation are considered to be the main cause of cancer. Genes that cause cancer are of two distinct types: oncogenes and onco-suppressor genes. The normal proto-oncogene can be converted into an active oncogene by deletion or point mutation in its coding sequence, gene amplification, and by specific chromosome rearrangements. Mutations and abnormal expression in ras, myc, c-erbB-2, and other oncogenes have been reported in several types of gynecological cancer. Onco-suppressor genes are involved in gynecological cancer, their functions are localized in different phases of the cell cycle. Structural changes and deletions of these genes can cause cancer. Mutations in the p53, BRCA1, DCC, and PTEN genes have been reported in gynecological cancers such as ovarian, cervical, and endometrial cancer. Human papillomaviruses are of major interest because specific types (HPV-16, -18, and several others) have been identified as causative agents in at least 90% of cancers of the cervix. In this study we summarize the available information regarding the implication of specific oncogenes, onco-suppressor genes, and HPV in the development of female genital malignancies.
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PMID:Molecular basis of gynecological cancer. 1081 92

Cyclin-dependent kinase inhibitors p16(INK4a), p21(Cip1), and p27(Kip1) are regarded as key effectors of cellular senescence. In this review, we describe three senescence-inducing pathways involving these inhibitors, namely, the p16(INK4a)/Rb pathway, the p19(ARF)/p53/p21(Cip1) pathway, and the PTEN/p27(Kip1) pathway. We emphasize the participation of tumor suppressors and oncogenes in the regulation of these senescence-inducing pathways. Finally, we discuss the impact of the Ras and Myc oncogenes on the above-mentioned pathways.
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PMID:Tumor suppressors and oncogenes in cellular senescence. 1083 53


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