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)

Overexpression of p53 protein, epidermal growth factor receptor (EGF-R), and c-erbB-2 protein was assessed by immunohistochemical staining of formalin-fixed, paraffin-embedded tissue from 64 invasive breast tumors. The correlation between abnormal expression of each protein and various disease parameters, including lymph node metastasis and histopathologic type and grade was analyzed. Despite the previous proposal, no significant correlation was found between lymph node metastases and overexpression of each gene in the primary tumors. In addition, some metastatic lesions did not always exhibit overexpression, even if it was evident in the primary tumors. Overexpression of c-erbB-2 protein correlated well with Bloom's histological grading. p53 expression was detected most often in tumors with hyperchromatism and more frequent mitosis. Overexpression of c-erbB-2 protein occurred more frequently in p53-positive tumors. The results indicate that abnormal expression of p53 protein causes genetic instability in the early stage of tumor development, resulting in subsequent overexpression of other oncogenes.
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PMID:Overexpression of p53, c-erbB-2 and epidermal growth factor receptor in human breast carcinomas. 1084 49

Infiltrating lobular carcinoma (ILC) and infiltrating ductal carcinoma (IDC) are similar in many respects and their histologic features occasionally overlap. Despite the many similarities, some clinical follow-up data and the patterns of metastasis suggest that ILC and IDC are biologically distinct. Unfortunately, most breast cancer research has focused almost exclusively on the ductal subtype or has not stressed the biologic or molecular genetic distinctions between breast carcinoma subtypes. Several reports have suggested the possibility that ILCs and IDCs differ with respect to expression of antigens involved in proliferation and cell cycle regulation. Therefore, we undertook an immunohistochemical evaluation of cell cycle related antigens in ILCs, including histologic variants thought to represent aggressive neoplasms, and IDCs matched for histologic grade (Modified Bloom-Richardson Grade I). We believe that different antigen expression profiles could elucidate the biological distinctiveness of breast carcinoma subtypes and possibly provide diagnostically relevant information. We studied the expression of the following antigens in 28 archived, formalin-fixed ILCs and 34 well-differentiated IDCs: estrogen receptor (ER), progesterone receptor (PR), Her 2-neu, mib-1, cyclin D1, p27, p53, mdm-2 and bcl-2. 94% of ILCs and 100% of IDCs expressed ER; 75% of ILCs and 76% of IDCs expressed PR; 4% of ILCs and 13% of IDCs expressed c cerb B-2; ILCs and IDCs both expressed mib-1 in approximately 10% of lesional cells; 82% of ILCs and 54% of IDCs expressed cyclin D1; 90% of ILCs and 83% IDCs expressed p27 strongly; 4% of ILCs and 4% of IDCs expressed p53, 25% of ILCs and 33% of IDCs expressed mdm-2; 96% of ILCs and 100% of IDCs expressed bcl-2. None of the apparent differences were statistically significant. The ILC variants demonstrated immunophenotypes that were essentially similar to ILCs of the usual type. We conclude that ILCs and well-differentiated IDCs show similar proliferation and cell cycle control antigen profiles. Despite their unusual histologic features, most ILC variants appear to maintain a characteristic ILC immunophenotype.
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PMID:A comparison of cell cycle markers in well-differentiated lobular and ductal carcinomas. 1094 2

The average length of telomere repeats at the ends of chromosomes in most normal human somatic cells has been found to decrease by 50-200 base pairs with each cell division. The loss of telomere repeats has been causally linked to replicative senescence by the demonstration that overexpression of the enzyme telomerase can result in the elongation or maintenance of telomeres and immortalization of somatic cells with a diploid and apparently normal karyotype. Major questions that remain are related to the actual mechanism by which telomere shortening induces replicative senescence and the importance of telomere shortening and replicative senescence in the homeostasis of cells in renewal tissues and aging. This perspective is concerned with the consequences of telomere shortening at individual chromosomes in individual cells. Experimental evidence indicates that short telomeres accumulate prior to senescence and that replicative senescence is not triggered by the first telomere to reach a critical minimal threshold length. These observations are compatible with limited repair of short telomeres by telomerase-dependent or telomerase-independent DNA repair pathways. Deficiencies in telomere repair may result in accelerated senescence and aging as well as genetic instability that facilitates malignant transformation. Examples of molecules that may have a role in the repair of telomeric DNA prior to replicative senescence include ATM, p53, PARP, DNA-PK, Ku70/80, the human hRad50-hMre11-p95 complex, BRCA 1 and 2 and the helicases implicated in Bloom's and Werner's syndrome.
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PMID:Repair of telomeric DNA prior to replicative senescence. 1098 22

Nuclear domains called ND10 or PML nuclear bodies consist of an aggregation of several proteins, most notably PML and Sp100. PML is essential in the nucleation and formation of ND10 as well as in the recruitment of other ND10-associated proteins such as Daxx, pRb, BLM and Sp100. In cells induced to overexpress Sp100, ND10 binding of Sp100 was saturable and excess Sp100 formed new aggregation sites devoid of other ND10-associated proteins, suggesting that homo-oligomerization is the basis for aggregation. To determine whether Sp100 binds to ND10 through hetero- or oligomerization, Sp100 deletion variants fused with GFP were transfected into cells with and without endogenous Sp100, and the localization of the GFP-labeled fragments was determined relative to ND10. Amino acids 29-152 were sufficient for deposition of the GFP-labeled fragments at ND10 in the absence of endogenous Sp100 (heterologous binding) and for self-aggregation (formation of new Sp100 deposits). None of the shorter fragments was deposited at ND10 or self-aggregated. The 29-152 amino acid fragment and some larger fragments, but not the full-size Sp100, induced elongation of ND10, which at their ends contain only Sp100, probably due to self-aggregation. By fusing a peptide consisting of the p53-binding domain from hMDM2 to the Sp100(29-152) fragment, this self-aggregation could be blocked while retaining the limited ND10 binding capacity, indicating that the Sp100 self-aggregation domain and the ND10 binding domain are separate entities. This fusion peptide was used to demonstrate the potential of ND10 to recruit p53 as a protein not usually present at this site. Such deposited p53 was protected from turnover. The capacity of ND10 to recruit Sp100 may serve primarily to reduce its availability.
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PMID:Evidence for separate ND10-binding and homo-oligomerization domains of Sp100. 1111 90

This paper examines the genetic defects associated with inherited cancer syndromes and their relevance to oral cancer. Tumour suppressor genes are now thought of as either gatekeepers or caretakers according to whether they control cell growth directly by inhibiting cell proliferation and/or promoting cell death (gatekeepers) or whether they maintain the integrity of the genome by DNA repair mechanisms (caretakers). In disorders such as xeroderma pigmentosum, ataxia telangiectasia, Bloom syndrome and Fanconi's anaemia, where there are defective caretaker genes, there is an increased incidence of second primary malignancies, including oral cancer. By contrast, with the exception of Li Fraumeni syndrome, abnormalities of gatekeeper genes do not predispose to oral cancer. Not only do Li Fraumeni patients develop second primary malignancies, but defects of the p53 pathway (p53 mutation, MDM2 over-expression, CDKN2A deletion) appear to be a ubiquitous feature of sporadic oral cancer as it occurs in the West. The findings suggest that genetic instability is of fundamental importance in the pathogenesis of oral cancer.
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PMID:A review of inherited cancer syndromes and their relevance to oral squamous cell carcinoma. 1185 72

Bloom's syndrome (BS), a rare genetic disease, arises through mutations in both alleles of the BLM gene which encodes a 3'-5' DNA helicase identified as a member of the RecQ family. BS patients exhibit a high predisposition to development of all types of cancer affecting the general population and BLM-deficient cells display a strong genetic instability. We recently showed that BLM protein expression is regulated during the cell cycle, accumulating to high levels in S phase, persisting in G2/M and sharply declining in G1, suggesting a possible implication of BLM in a replication (S phase) and/or post-replication (G2 phase) process. Here we show that, in response to ionizing radiation, BLM-deficient cells exhibit a normal p53 response as well as an intact G1/S cell cycle checkpoint, which indicates that ATM and p53 pathways are functional in BS cells. We also show that the BLM defect is associated with a partial escape of cells from the gamma-irradiation-induced G2/M cell cycle checkpoint. Finally, we present data demonstrating that, in response to ionizing radiation, BLM protein is phosphorylated and accumulates through an ATM-dependent pathway. Altogether, our data indicate that BLM participates in the cellular response to ionizing radiation by acting as an ATM kinase downstream effector.
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PMID:ATM-dependent phosphorylation and accumulation of endogenous BLM protein in response to ionizing radiation. 1114 46

Deficiency in a helicase of the RecQ family is found in at least three human genetic disorders associated with cancer predisposition and/or premature ageing. The RecQ helicases encoded by the BLM, WRN and RECQ4 genes are defective in Bloom's, Werner's and Rothmund-Thomson syndromes, respectively. Cells derived from individuals with these disorders in each case show inherent genomic instability. Recent studies have demonstrated direct interactions between these RecQ helicases and human nuclear proteins required for several aspects of chromosome maintenance, including p53, BRCA1, topoisomerase III, replication protein A and DNA polymerase delta. Here, we review this network of protein interactions, and the clues that they present regarding the potential roles of RecQ family members in DNA repair, replication and/or recombination pathways.
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PMID:DNA helicase deficiencies associated with cancer predisposition and premature ageing disorders. 1125 7

Bloom syndrome (BS) is an autosomal recessive disorder characterized by a high incidence of cancer and genomic instability. BLM, the protein defective in BS, is a RecQ-like helicase, presumed to function in DNA replication, recombination, or repair. BLM localizes to promyelocytic leukemia protein (PML) nuclear bodies and is expressed during late S and G2. We show, in normal human cells, that the recombination/repair proteins hRAD51 and replication protein (RP)-A assembled with BLM into a fraction of PML bodies during late S/G2. Biochemical experiments suggested that BLM resides in a nuclear matrix-bound complex in which association with hRAD51 may be direct. DNA-damaging agents that cause double strand breaks and a G2 delay induced BLM by a p53- and ataxia-telangiectasia mutated independent mechanism. This induction depended on the G2 delay, because it failed to occur when G2 was prevented or bypassed. It coincided with the appearance of foci containing BLM, PML, hRAD51 and RP-A, which resembled ionizing radiation-induced foci. After radiation, foci containing BLM and PML formed at sites of single-stranded DNA and presumptive repair in normal cells, but not in cells with defective PML. Our findings suggest that BLM is part of a dynamic nuclear matrix-based complex that requires PML and functions during G2 in undamaged cells and recombinational repair after DNA damage.
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PMID:Regulation and localization of the Bloom syndrome protein in response to DNA damage. 1130 17

The Bloom syndrome (BS) protein, BLM, is a member of the RecQ DNA helicase family that also includes the Werner syndrome protein, WRN. Inherited mutations in these proteins are associated with cancer predisposition of these patients. We recently discovered that cells from Werner syndrome patients displayed a deficiency in p53-mediated apoptosis and WRN binds to p53. Here, we report that analogous to WRN, BLM also binds to p53 in vivo and in vitro, and the C-terminal domain of p53 is responsible for the interaction. p53-mediated apoptosis is defective in BS fibroblasts and can be rescued by expression of the normal BLM gene. Moreover, lymphoblastoid cell lines (LCLs) derived from BS donors are resistant to both gamma-radiation and doxorubicin-induced cell killing, and sensitivity can be restored by the stable expression of normal BLM. In contrast, BS cells have a normal Fas-mediated apoptosis, and in response to DNA damage normal accumulation of p53, normal induction of p53 responsive genes, and normal G(1)-S and G(2)-M cell cycle arrest. BLM localizes to nuclear foci referred to as PML nuclear bodies (NBs). Cells from Li-Fraumeni syndrome patients carrying p53 germline mutations and LCLs lacking a functional p53 have a decreased accumulation of BLM in NBs, whereas isogenic lines with functional p53 exhibit normal accumulation. Certain BLM mutants (C1055S or Delta133-237) that have a reduced ability to localize to the NBs when expressed in normal cells can impair the localization of wild type BLM to NBs and block p53-mediated apoptosis, suggesting a dominant-negative effect. Taken together, our results indicate both a novel mechanism of p53 function by which p53 mediates nuclear trafficking of BLM to NBs and the cooperation of p53 and BLM to induce apoptosis.
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PMID:Functional interaction of p53 and BLM DNA helicase in apoptosis. 1139 66

Bloom syndrome (BS) is characterized by premature aging and high predisposition to various types of cancer. BLM is the causative gene for BS. BLM functions as a DNA helicase in the direction of 3' to 5' and small subsets of telomeres colocalize with BLM protein. We investigated telomerase activity and telomere repeat length in the cells from BS patients. In Epstein-Barr-virus (EBV) transformed lymphoblastoid cell lines and lymphoma cells from BS patients, telomerase activity was detected as in the control and compared. The metastatic tumor from BS patient, which had a 9-bp deletion of p53 DNA showed the strongest telomerase activity. Telomere repeat length in BS cells showed that there is no large difference compared with normal cells. Collectively, the results show that the BLM gene is not a major structural and regulatory factor in maintaining telomere repeat length and telomerase activity.
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PMID:Telomerase activity in cell lines and lymphoma originating from Bloom syndrome. 1169 6


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