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)

The p53 protein has a highly evolutionarily conserved role in metazoans as 'guardian of the genome', mediating cell-cycle arrest and apoptosis in response to genotoxic injury. In large, long-lived animals with substantial somatic regenerative capacity, such as vertebrates, p53 is an important tumour suppressor--an attribute thought to stem directly from its induction of death or arrest in mutant cells with damaged or unstable genomes. Chemotherapy and radiation exposure both induce widespread p53-dependent DNA damage. This triggers potentially lethal pathologies that are generally deemed an unfortunate but unavoidable consequence of the role p53 has in tumour suppression. Here we show, using a mouse model in which p53 status can be reversibly switched in vivo between functional and inactive states, that the p53-mediated pathological response to whole-body irradiation, a prototypical genotoxic carcinogen, is irrelevant for suppression of radiation-induced lymphoma. In contrast, delaying the restoration of p53 function until the acute radiation response has subsided abrogates all of the radiation-induced pathology yet preserves much of the protection from lymphoma. Such protection is absolutely dependent on p19(ARF)--a tumour suppressor induced not by DNA damage, but by oncogenic disruption of the cell cycle.
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PMID:The pathological response to DNA damage does not contribute to p53-mediated tumour suppression. 1697 34

Epigenetic silencing of tumour suppressor genes (TSG) inactivates TSG functions. Previously, we identified PCDH10 as a methylated TSG in carcinomas. Here, we detected its frequent silencing and methylation in lymphoma cell lines including 100% Burkitt, 100% diffuse large B cell, 86% Hodgkin, 100% nasal natural killer/T-cell lymphoma and 1/3 of leukaemia cell lines, and in primary tumours but not in normal peripheral blood mononuclear cells or lymph nodes. PCDH10 silencing could be reversed by demethylation with 5-aza-2'-deoxycytidine. Methylation was further detected in 14% of Hodgkin lymphoma sera. Thus, PCDH10 methylation is frequently involved in lymphomagenesis and could serve as a tumour-specific biomarker.
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PMID:Frequent epigenetic silencing of protocadherin 10 by methylation in multiple haematologic malignancies. 1734 Dec 68

Intravascular angiotropic lymphoma (IVL) is a rare variant of non-Hodgkin's lymphoma. Diagnosis in most cases is only achieved at post-mortem. We present a patient with pyrexia of unknown origin diagnosed with angiotropic lymphoma by bone marrow biopsy. We also review the limited published literature on associated chromosomal abnormalities. We provide further support for previously proposed non-random changes in IVL, namely, structural aberrations of chromosomes 1, 6 and 10, as well as identify further aberrations that may be non-random in chromosomes 4, 5 and 8, and postulate that the 6q21-24 region may be the site of a tumour suppressor gene. B-cell angiotropic lymphoma is a rare, but important, cause of pyrexia of unknown origin and we advocate that prolonged fever that has resisted diagnosis should prompt histological and immunocytochemical examination of bone marrow to facilitate rapid diagnosis and early institution of treatment.
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PMID:Angiotropic lymphoma: Associated chromosomal abnormalities. 1769 34

MicroRNAs are a recently discovered class of short (approximately 22 nucleotide) naturally occurring RNA molecules that negatively regulate gene expression post-transcriptionally. There has been an explosion of interest in the microRNA field as these molecules have been found to play key roles in a wide range of biological processes and to be aberrantly expressed in many types of cancer, including haematological malignancies. Cancer-associated microRNAs can act as both tumour suppressor molecules (e.g., miR-15a and miR-16-1) and have oncogenic properties (e.g., miR-155 and miR-17-92 cluster). In this review the authors discuss the rapidly accumulating evidence for the central role that microRNAs play in both haematopoiesis and haematological malignancy, in particular focusing on their role in lymphoma.
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PMID:MicroRNA expression in lymphoma. 1772 26

Neuroblastoma (NB) is, next to acute lymphoblastic leukaemia, brain tumours and lymphoma the most frequent paediatric tumour (8-10%). Our research group aims to contribute to the unravelling of the genetic basis of NB. Insight into the genes and signalling pathways involved in tumour formation and development can represent an essential step towards the development of more efficient molecular targeted therapies. A first part of our research work was devoted to the analysis of genomic alterations in NB. By means of a new highly sensitive method for detecting gains and losses of chromosomal segments, we recognised three major prognostic relevant genomic subtypes of NB. In addition smaller subgroups with deviating genomic patterns were detected. In addition, this work yielded important information regarding delineation of critical regions of gain and loss in NB which should facilitate further selection of candidate oncogenes or tumour suppressor genes. A second important part of our work focussed on the gene expression profiling of NB precursor cells. We were able as the first to isolate these cells and determine their transcriptome, a finding of fundamental importance for future expression studies in NB. Another study focussed on the identification of MYCN transcriptional target genes. Gene expression analyses of model systems developed in our lab and of a large panel of cell lines and tumours allowed us to subtract a list of candidate genes which are now under further study. Finally, we initiated research towards the understanding of the role of methylation in NB oncogenesis. From this, we were able to create a list of potentially relevant methylated genes in NB. From the above it is clear that our team has made important contributions to the understanding of the complex biology and clinical behaviour of NB. Also, a broad technically innovative research platform has been developed which will allow us to dissect NB genetics with greater speed and accuracy.
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PMID:[New insights into the genetic basis of neuroblastoma]. 1782 57

ZBTB7A (Pokemon) is a member of the POK family of transcriptional repressors. Its main function is the suppression of the p14ARF tumour suppressor gene. Although ZBTB7A expression has been found to be increased in various types of lymphoma, there are no reports dealing with its expression in solid tumours. Given that p14(ARF) inhibits MDM2, the main negative regulator of p53, we hypothesized that overexpression of ZBTB7A could lead indirectly to p53 inactivation. To this end, we examined the status of ZBTB7A and its relationship with tumour kinetics (proliferation and apoptosis) and nodal members of the p53 network in a panel of 83 non-small cell lung carcinomas (NSCLCs). We observed, in the majority of the samples, prominent expression of ZBTB7A in the cancerous areas compared to negligible presence in the adjacent normal tissue elements. Gene amplification (two- to five-fold) was found in 27.7% of the cases, denoting its significance as a mechanism driving ZBTB7A overproduction in NSCLCs. In the remaining non-amplified group of carcinomas, analysis of the mRNA and protein expression patterns suggested that deregulation at the transcriptional and post-translational level accounts for ZBTB7A overexpression. Proliferation was associated with ZBTB7A expression (p = 0.033) but not apoptosis. The association with proliferation was reflected in the positive correlation between ZBTB7A expression and tumour size (p = 0.018). The overexpression of ZBTB7A in both p53 mutant and p53 wild-type cases, implies either a synergistic effect or that ZBTB7A exerts its oncogenic properties independently of the p14(ARF)-MDM2-p53 axis. The concomitant expression of ZBTB7A with p14(ARF) (p = 0.039), instead of the anticipated inverse relation, supports the latter notion. In conclusion, regardless of the pathway followed, the distinct expression of ZBTB7A in cancerous areas and the association with proliferation and tumour size pinpoints a role for this novel cell cycle regulator in the pathogenesis of lung cancer.
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PMID:Gene amplification is a relatively frequent event leading to ZBTB7A (Pokemon) overexpression in non-small cell lung cancer. 1790 53

Tyrosine kinase Fyn, the expression of which is epigenetically regulated, has been proposed to be a tumour suppressor gene. A frequent deletion at the 6q chromosomal region encoding the Fyn gene in lymphomas has been reported. Therefore, we assessed the impact of 5-Aza-2'-deoxycytidine (5-dAzaC), a DNA methyltransferase (DNMTs) inhibitor on Fyn expression in Hut-78 T-lymphoma cells. Using reverse transcription, real-time quantitative PCR (RQ-PCR), and western blot analyses, we found that 5-dAzaC significantly increased transcript and protein levels of Fyn in Hut-78 T-lymphoma cells. However, bisulfite sequencing revealed that Hut-78 T-lymphoma cells cultured in the absence of 5-dAzaC contained unmethylated cytosine in the cytosine-guanosine dinucleotide island of the Fyn promoter. Our results suggest that the DNMTs activity may have an indirect influence on the expression of Fyn without altering the methylation level of its promoter in Hut-78 T-lymphoma cells.
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PMID:Inhibition of DNA methyltransferase activity upregulates Fyn tyrosine kinase expression in Hut-78 T-lymphoma cells. 1833 55

Evasion of apoptosis contributes importantly to c-Myc-induced tumorigenesis. The BH3-only Bcl-2 family members Puma and Noxa are critical pro-apoptotic transcriptional targets of p53, a major mediator of Myc-induced apoptosis and suppressor of Myc-induced tumorigenesis. Hence, we have explored the impact of their individual or combined loss on myc-driven lymphomagenesis. Notably, Puma deficiency both increased B-lineage cells and accelerated the development of B lymphoma, accompanied by leukaemia, but not of pre-B lymphoma. Noxa deficiency alone also increased B-lineage cells but did not accelerate lymphomagenesis. However, its deficiency combined with loss of one puma allele produced more rapid onset of both pre-B and B lymphomas than did loss of a single puma allele alone. Nevertheless, the acceleration evoked by loss of both genes was not as marked as that caused by p53 heterozygosity. These results show that Puma imposes a significant, and Noxa a minor barrier to c-Myc-driven lymphomagenesis. They also indicate that additional BH3-only proteins probably also drive Myc-induced apoptosis and that non-apoptotic functions of p53 may contribute substantially to its tumour suppressor role.
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PMID:Puma and to a lesser extent Noxa are suppressors of Myc-induced lymphomagenesis. 1914 84

Diffuse large B-cell lymphoma (DLBCL), the most common form of lymphoma in adulthood, comprises multiple biologically and clinically distinct subtypes including germinal centre B-cell-like (GCB) and activated B-cell-like (ABC) DLBCL. Gene expression profile studies have shown that its most aggressive subtype, ABC-DLBCL, is associated with constitutive activation of the NF-kappaB transcription complex. However, except for a small fraction of cases, it remains unclear whether NF-kappaB activation in these tumours represents an intrinsic program of the tumour cell of origin or a pathogenetic event. Here we show that >50% of ABC-DLBCL and a smaller fraction of GCB-DLBCL carry somatic mutations in multiple genes, including negative (TNFAIP3, also called A20) and positive (CARD11, TRAF2, TRAF5, MAP3K7 (TAK1) and TNFRSF11A (RANK)) regulators of NF-kappaB. Of these, the A20 gene, which encodes a ubiquitin-modifying enzyme involved in termination of NF-kappaB responses, is most commonly affected, with approximately 30% of patients displaying biallelic inactivation by mutations and/or deletions. When reintroduced in cell lines carrying biallelic inactivation of the gene, A20 induced apoptosis and cell growth arrest, indicating a tumour suppressor role. Less frequently, missense mutations of TRAF2 and CARD11 produce molecules with significantly enhanced ability to activate NF-kappaB. Thus, our results demonstrate that NF-kappaB activation in DLBCL is caused by genetic lesions affecting multiple genes, the loss or activation of which may promote lymphomagenesis by leading to abnormally prolonged NF-kappaB responses.
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PMID:Mutations of multiple genes cause deregulation of NF-kappaB in diffuse large B-cell lymphoma. 1941 64

B-lymphoma Moloney murine leukaemia virus insertion region-1 (BMI1) is a member of the polycomb group of transcription repressors, which functions in stem cell maintenance and oncogenesis through the inhibition of the INK4A/ARF tumour suppressor locus. Overexpression of BMI1 is associated with poor prognosis in several human cancers, including breast cancer. We have previously shown that BMI1 collaborates with H-RAS to induce transformation of MCF10A human mammary epithelial cells through dysregulation of multiple growth pathways independent of the INK4A/ARF locus. In this study, we show that BMI1 collaborates with H-RAS to promote increased proliferation, invasion and resistance to apoptosis in vitro, and an increased rate of spontaneous metastases from mammary fat pad xenografts including novel metastases to the brain. Furthermore, in collaboration with H-RAS, BMI1 induced fulminant metastatic disease in the lung using a tail vein model of haematogenous spread through accelerated cellular proliferation and inhibition of apoptosis. Finally, we show that knockdown of BMI1 in several established breast cancer cell lines leads to decreased oncogenic behaviour in vitro and in vivo. In summary, BMI1 collaborates with H-RAS to induce an aggressive and metastatic phenotype with the unusual occurrence of brain metastasis, making it an important target for diagnosis and treatment of aggressive breast cancer.
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PMID:BMI1 cooperates with H-RAS to induce an aggressive breast cancer phenotype with brain metastases. 1954 17


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