Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P43146 (tumour suppressor)
 5,935 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Type I neurofibromatosis (NF1) is a common autosomal dominant disorder that affects tissues derived from the neural crest. The manifestations are varied, comprising generalised disorders of growth and development as well as an increased risk of benign and malignant tumours including phaeochromocytomas and neurofibrosarcomas. The NF1 locus has been mapped to chromosome bands 17q11-12, and recently the NF1 gene has been cloned. Deletions identified in the constitutional genotype of some patients have suggested that the NF1 phenotype may arise from loss of function mutations of the NF1 gene, consistent with the hypothesis that it is a tumour suppressor gene. To date, however, analysis of NF1 tumours has not revealed the frequent allele losses encompassing the NF1 locus, implying loss of the wild-type NF1 allele, which would support this hypothesis. We report allele losses with markers flanking the NF1 region in each of 7 NF1 phaeochromocytomas. In each of the 3 tumours for which this could be determined, the loss involved the wild-type chromosome. These results provide strong evidence that, in cells of the adrenal medulla at least, the NFI gene may act as a tumour suppressor.
 ...
PMID:Loss of NF1 alleles in phaeochromocytomas from patients with type I neurofibromatosis. 137 42

A 34-year-old woman who presented with hearing loss and tinnitus was found to have reduced vision bilaterally. Computed tomography scan revealed bilateral acoustic neuromas and bilateral optic nerve sheath meningiomas. The presence of bilateral acoustic neuromas fulfils the criteria for the diagnosis of central neurofibromatosis (neurofibromatosis type 2). Although this is the first report of bilateral optic nerve sheath meningioma in neurofibromatosis type 2, meningiomas are commoner in this dominantly inherited disorder, than in its absence and both forms of central nervous system tumour may be caused by loss of tumour suppressor genes on chromosome 22.
 ...
PMID:Bilateral optic nerve sheath meningiomas in a patient with neurofibromatosis type 2. 139 May 17

Bilateral acoustic neurofibromatosis (BANF) is a severe autosomal dominant disorder involving development of multiple tumours of the nervous system including meningiomas, gliomas, neurofibromas and particularly bilateral acoustic neuromas. We have used genetic linkage analysis with DNA markers to establish that the defective gene causing BANF is on chromosome 22, and is therefore distinct from the gene for the von Recklinghausen form of neurofibromatosis, which maps to chromosome 17. Linked DNA markers will be particularly valuable in BANF, facilitating early detection of tumours and thereby permitting more effective surgical intervention. In view of the reported loss of genes on chromosome 22 in meningiomas and acoustic neuromas, the genetic localization of the primary BANF defect strongly supports the concept that the disease locus encodes a 'tumour suppressor' gene. Isolation of this gene should provide insights into the pathogenesis of acoustic neuromas and other nervous system tumours, as well as into the control of proliferation and differentiation of neural crest cells.
 ...
PMID:Genetic linkage of bilateral acoustic neurofibromatosis to a DNA marker on chromosome 22. 288 21

Many tumours of the skull base, including schwannomas, paragangliomas, meningiomas and anterior pituitary tumours occur both as sporadic tumours and in clear cut familial syndromes. These cancers' highly penetrant dominantly inherited syndromes have proven to be a rich resource for locating tumour genes, most of which are of the tumour suppressor type. Recently, the gene for type 2 neurofibromatosis (NF2) was isolated by the technique of positional cloning. The NF2 gene has now been demonstrated to be involved in the pathogenesis of both familial and non-familial vestibular schwannomas as well as meningiomas. The presence of inactivating mutations within this gene suggests that it acts as a tumour suppressor and the mechanism has been shown to comply with a 'two hit' mutation model. Hereditary tumours constitute a small proportion of all cases, but evidence from studies of tumours such as vestibular schwannoma and meningioma have shown that their genes are also relevant to the much more common non-familial forms of the same tumour. This paper briefly describes the approach to locating tumour genes, and reviews our current knowledge regarding the chromosomal location and function of genes responsible for familial tumours involving the skull base. The genetic mechanisms of tumourigenesis are discussed as are the prospects for the development of novel forms of diagnosis and treatment.
 ...
PMID:Genetics of familial and non-familial skull base tumours. 778 35

Neurological tumours are common neoplasms of both adults and children. Recent studies have begun to delineate the genetic abnormalities that underlie such tumours, and have implicated two classes of genes, oncogenes and tumour suppressor genes. Most investigations have focused on those astrocytomas that affect the cerebral hemispheres of adults, since these are the most common and malignant brain tumours. The high-grade astrocytomas that affect adults, such as glioblastoma multiforme, often have amplification of the epidermal growth factor receptor (EGFR) oncogene and loss of a variety of chromosomal loci that probably harbour tumour suppressor genes. Of the various tumour suppressor gene loci, the p53 gene on chromosome 17p has been studied most closely and has been shown to be mutated in both low- and high-grade astrocytomas. These genetic alterations may provide a means for subdividing astrocytomas into diagnostic categories. For instance, p53 gene mutations occur more commonly in glioblastomas from young adults and women, while EGFR gene amplification is more common in glioblastomas from older adults and men. For the other primary CNS tumours, genetic studies remain in their infancy. The neurocutaneous syndromes, such as neurofibromatosis types 1 and 2, have provided unique insights into neurological oncogenesis. The NF1 gene on chromosomes 17q and its product, neurofibromin, may be important in the formation of neurofibrosarcomas, while the NF2 gene on chromosome 22q and its product, merlin, are probably involved in the formation of schwannomas and other nervous system tumours. The further characterization of these and other neurological tumour genes will undoubtedly illuminate many other areas in neurooncology.
 ...
PMID:Genetic basis of neurological tumours. 795 51

The aim of the present study was to investigate loss of heterozygosity (LOH) or microsatellite instability in chronic myeloid leukaemia (CML) blast crisis at genomic locations which are known or postulated to harbour tumour suppressor genes. We studied 48 patients in blast crisis of myeloid (n = 31), lymphoid (n = 15), megakaryocytic (n = 1), or mixed lineage (n = 1) phenotype by comparing constitutional DNA extracted from buccal epithelial cells or chronic phase leucocytes with DNA obtained from blast crisis leucocytes. Twelve variable number tandem repeat loci from six different chromosomes were amplified by polymerase chain reaction using labelled primers, and fractionated on polyacrylamide gels. After autoradiography, length as well as intensity of the amplified products were compared between constitutional and blast crisis samples. LOH was scored as complete, partial or none in informative patients. Complete LOH was found in one patient at 8p22 and another at 13q14; partial LOH was detected in three patients at 11p13 and/or 11p15. No LOH was found at 6q27, 8p21, 18q21, 22q11-12 and 22q13 in any patient. Furthermore, no consistent difference in allelic length was observed in 517 paired amplifications indicating no microsatellite instability. We conclude that the Rb gene at 13q14, the Wilms tumour gene at 11p13, the DCC gene at 18q21, the neurofibromatosis 2 gene at 22q11-13 and uncloned tumour suppressor genes at 6q27, 8p21-22 and 11p15, as well as genes responsible for microsatellite instability, are unlikely to be involved in the progression of CML to blast crisis in the majority of patients.
 ...
PMID:No evidence for microsatellite instability or consistent loss of heterozygosity at selected loci in chronic myeloid leukaemia blast crisis. 796 38

The neurofibromatosis 2 gene (NF2) has recently been isolated and predicted to encode a novel protein related to the moesin-ezrin-radixin family of cytoskeleton-associated proteins. Here we describe a novel isoform of the NF2 transcript that shows differential tissue expression and encodes a modified C terminus of the predicted protein. Mutations affecting both isoforms of the NF2 transcript were detected in multiple tumour types including melanoma and breast carcinoma. These findings provide evidence that alterations in the NF2 transcript occur not only in the hereditary brain neoplasms typically associated with NF2, but also as somatic mutations in their sporadic counterparts and in seemingly unrelated tumour types. The NF2 gene may thus constitute a tumour suppressor gene of more general importance in tumorigenesis.
 ...
PMID:Mutations in transcript isoforms of the neurofibromatosis 2 gene in multiple human tumour types. 816 73

We are studying the biological activity and regulation of mammalian Ras protein in tumours and in physiological signalling. We have shown that GAP (the GTPase-activating protein) is a potent negative regulator of normal Ras in cells. Reduction or loss of the NF1 gene product neurofibromin, in association with genetic abnormalities of the NF1 locus, has been identified in schwannoma cell lines from patients with neurofibromatosis and in melanoma and neuroblastoma lines from patients without neurofibromatosis. Although loss of neurofibromin in the schwannoma lines was associated with a high proportion of normal Ras protein in the active GTP-bound state, Ras-GTP appeared to be appropriately regulated in the melanoma and neuroblastoma lines, which contain normal levels of GAP. Therefore the GTPase-activating activity of neurofibromin is not essential for negative regulation of Ras in some cell types and the putative tumour suppressor function of neurofibromin in such cell types is independent of its GTPase-activating activity. Mitogen activation of Ras in fibroblasts is mediated primarily by exchange factors, which probably interact with a region on the Ras protein distinct from the region required for interaction with GAP. Multiple full-length cDNAs have identified a mouse gene whose products are related to yeast CDC25 guanine nucleotide exchange factor.
 ...
PMID:Cell transformation by ras and regulation of its protein product. 829 27

In a patient with neurofibromatosis (von Recklinghausen disease; NF1), normal lymphocytes, five cutaneous neurofibromas, and tumour tissue from a recurrence of a malignant schwannoma were analysed for genetic alterations. Eleven DNA markers located on chromosome 17 and nine randomly chosen markers representing chromosomes 1, 2, 3, 4, 5, 6, and 11, were analysed. High resolution Giemsa banding of lymphocytes revealed no chromosomal rearrangement. The DNA from the neurofibromas were all found to have the same restricted fragment length polymorphism pattern as the constitutional DNA from the patient. In the malignant schwannoma a complete loss of one allele was found at polymorphic loci on chromosome arm 17p. One gene copy of the TP53 gene (17p13.1) and the NF1 gene (17q11.2) was lost, as was one copy of the PGA gene (11q13). No mutations were detected in the mutational hotspots of the TP53 gene. Partial losses were detected at three loci on chromosomes 1, 2 and 6, indicating a clonal variation within the tumour since histological evaluation disclosed no normal tissue in the analysed specimen. Our data indicate that the NF1 gene may function as a tumour suppressor gene, and that, either by effect of dose reduction or complete inactivation, both the NF1 gene and the TP53 gene may be critical for the progression of a neurofibroma to a malignant schwannoma. The observations made are consistent with the concept of stepwise multigenetic changes in tumour progression.
 ...
PMID:Genetic alterations in a malignant schwannoma from a patient with neurofibromatosis (NF1). 835 Dec 50

A hallmark clinical feature of neurofibromatosis 1 (NF1) is multiple dermal neurofibromas, benign tumours that typically appear in early adolescence and increase in numbers throughout life. The pathogenesis of these tumours is not known. One domain of the NF1 gene product, neurofibromin, stimulates the intrinsic GTPase of Ras, and inactivation of both NF1 alleles has been demonstrated in specific malignancies. These observations support the contention that the NF1 gene product is a tumour suppressor that is involved in the Ras signal transduction pathway. Even though accumulating evidence demonstrates that NF1 acts as a tumour suppressor in some cells, mutations have not been identified in both NF1 alleles in dermal neurofibromas. Using standard techniques to analyse DNA extracted from benign neurofibromas, numerous investigators failed to identify loss of heterozygosity (LOH) in multiple tumours. In contrast to these reports, Colman et al. demonstrated NF1 LOH of dermal neurofibromas derived from 2 of 5 NF1 patients, yet the constitutional NF1 mutations in these patients were not identified, and the extent of the somatic deletions beyond the NF1 locus were not established. In this study, we show that a dermal neurofibroma from an NF1 individual who has a constitutional deletion of the entire NF1 locus harbours a 4-bp deletion of NF1 exon 4b in the other allele. This is the first definitive identification of a somatic mutation which is limited to the NF1 locus in a benign neurofibroma from an NF1 individual in whom the constitutional NF1 mutation is known.
 ...
PMID:Identification of NF1 mutations in both alleles of a dermal neurofibroma. 878 31


1 2 3 4 Next >>