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)

Abnormalities precipitated by a targeted truncation in the murine gene Brca2 define its involvement in DNA repair. In culture, cells harboring truncated Brca2 exhibit a proliferative impediment that worsens with successive passages. Arrest in the G1 and G2/M phases is accompanied by elevated p53 and p21 expression. Increased sensitivity to genotoxic agents, particularly ultraviolet light and methylmethanesulfonate, shows that Brca2 function is essential for the ability to survive DNA damage. But checkpoint activation and apoptotic mechanisms are largely unaffected, thereby implicating Brca2 in repair. This is substantiated by the spontaneous accumulation of chromosomal abnormalities, including breaks and aberrant chromatid exchanges. These findings define a function of Brca2 in DNA repair, whose loss precipitates replicative failure, mutagen sensitivity, and genetic instability reminiscent of Bloom syndrome and Fanconi anemia.
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PMID:Involvement of Brca2 in DNA repair. 966 Sep 19

DNA repair status is recognized as an important determinant of the clinical efficacy of cancer chemotherapy. To assess the role that a mammalian DNA glycosylase plays in modulating the toxicity and clastogenicity of the chemotherapeutic DNA cross-linking alkylating agents, we compared the sensitivity of wild-type murine cells to that of isogenic cells bearing homozygous null mutations in the 3-methyladenine DNA glycosylase gene (Aag). We show that Aag protects against the toxic and clastogenic effects of 1,3-bis(2-chloroethyl)-1-nitrosourea and mitomycin C (MMC), as measured by cell killing, sister chromatid exchange, and chromosome aberrations. This protection is accompanied by suppression of apoptosis and a slightly reduced p53 response. Our results identify 3-methyladenine DNA glycosylase-initiated base excision repair as a potentially important determinant of the clinical efficacy and, possibly, the carcinogenicity of these widely used chemotherapeutic agents. However, Aag does not contribute significantly to protection against the toxic and clastogenic effects of several chemotherapeutic nitrogen mustards (namely, mechlorethamine, melphalan, and chlorambucil), at least in the mouse embryonic stem cells used here. We also compare the Aag null phenotype with the Fanconi anemia phenotype, a human disorder characterized by cellular hypersensitivity to DNA cross-linking agents, including MMC. Although Aag null cells are sensitive to MMC-induced growth delay and cell cycle arrest, their sensitivity is modest compared to that of Fanconi anemia cells.
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PMID:Mammalian 3-methyladenine DNA glycosylase protects against the toxicity and clastogenicity of certain chemotherapeutic DNA cross-linking agents. 973 10

Apoptosis is associated with caspase-mediated proteolysis of Type I (K18 and K19) cytokeratins. We previously showed a positive association between the levels of tissue polypeptide antigen (TPA), that recognizes cytokeratins K8, K18, and K19 fragments, and induced apoptosis in breast cancer cell lines. The aim of the present study was to evaluate the interrelationships between TPA, steroid receptors, and p53, and their joint prognostic role in node-negative breast cancer patients not treated with adjuvant therapies. Age and pT were also considered since they are known prognostic factors. Five hundred and ninety-nine cases with N- breast cancer were evaluated (median follow-up: 60 months). TPA was measured by an immunoradiometric assay and p53 by an immunochemiluminescent assay in tumor cytosol. Multiple correspondence analysis was used to study the associations among variables. Their prognostic role (univariate analysis) and their joint effect (multivariate analysis) on RFS were investigated with Cox regression models. TPA showed a direct association with ER and PgR. Higher p53 values were weakly associated to low values of ER, PgR, and TPA. Younger age was related to low and intermediate values of ER and PgR and to low p53 values, while older age was related to high values of ER. Multivariate analysis showed a significant prognostic impact for pT, age, ER, and TPA. Among the interactions considered clinically relevant, only that between ER and age was found. RFS estimated values were poorer in cases with lower than in those with higher TPA values, both in patients expected to have a poor (pT2, young age, low ER) and a better prognosis (pT1, older age, high ER). From the findings of the present study we can draw the following conclusions: The relationship of TPA with prognosis gives an additional contribution to pT, age, and steroid receptors in N- breast cancer; TPA may be considered the first marker of apoptosis measured with a fully standardized quantitative method in tumor cytosol and could be evaluated in prognostic indexes including markers related to different biological mechanisms.
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PMID:Quantitative measurement of soluble cytokeratin fragments in tissue cytosol of 599 node negative breast cancer patients: a prognostic marker possibly associated with apoptosis. 1083 91

Wild-type p53 protein has been shown to inhibit angiogenesis through thrombospondin in the preclinical setting. Here, we determined the associations between the expression of the angiogenic factor vascular endothelial growth factor (VEGF) and the p53 status, including different mutation sites and types, in primary breast cancer. Cytosols from 224 primary breast cancer patients were analyzed with an enzyme immunoassay for determination of human VEGF165 protein content. p53 status was determined by cDNA-based sequencing of the entire coding region, by immunohistochemistry (IHC), and by a p53 luminometric immunoassay (LIA) method. Statistically significant associations was found between higher VEGF content and non-wild-type p53 status for all methods; sequence-based data (P = 0.0019), IHC data (P = 0.0068), and the LIA method (r = 0.427; P > 0.001). Highest VEGF values were detected in tumors with p53 insertions, deletions, and stop codon mutations (P = 0.0043). Combining p53 status and VEGF content resulted in additional prognostic information, relapse-free survival (RFS; P = 0.0377), overall survival (OS; P = 0.0319), and breast cancer corrected survival (BCCS; P = 0.0292). In multivariate analysis, the relative hazard increased when the VEGF data were added to the p53 status, with a relative hazard of 1.7 for RFS and 3.0 for BCCS, compared with 1.1 for RFS and 1.4 for BCCS among the patients with either high VEGF content or p53 mutation. Higher VEGF content was statistically significantly correlated with a worse outcome for patients with estrogen receptor-positive tumors receiving adjuvant tamoxifen: RFS (P = 0.0471), OS (P = 0.0134), BCCS (P = 0.0064), as well as in multivariate analysis with point estimates of 3.4 and 2.1 for BCCS and RFS, respectively. VEGF expression is related to p53 status in human breast cancer patients. Combining VEGF with p53 status resulted in better prognostic prediction.
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PMID:The expression of vascular endothelial growth factor correlates with mutant p53 and poor prognosis in human breast cancer. 1128 Jul 95

To evaluate whether cellular markers predict the responsiveness to neoadjuvant chemotherapy (NAC) in cervical cancer, 21 patients with stages I and II cervical carcinomas treated by NAC before surgery were followed up for a mean of 52.3 months. Pre-NAC biopsy and operative specimens were subjected to counting of apoptotic (AI/V) and mitotic (MI/V) indices, detection of human papillomavirus (HPV) DNA, and immunohistochemical analysis of cell cycle and proliferation markers (p21, p53, pRb, proliferating cell nuclear antigen [PCNA], Ki-67) and multidrug resistance gene (MDR1), as related to NAC response (RAC), recurrence-free (RFS), and overall (OS) survival. Adenosquamous histology and lymph node involvement were significant determinants of nonsurvival. All carcinomas contained HPV DNA. In univariate analysis, p21, pRb, and MDRI in the biopsy specimen and PCNA, Ki-67, and pRb in the surgical sample significantly predicted RAC, while age, AI/V number of lymph nodes removed, and MI/V predicted RFS. Highly significant predictors of OS were AI/V number of lymph nodes removed, post-NAC MDR1 expression, MI/V and recurrence. Multivariate analysis confirmed the strong post-NAC effects of histologic type, AI/V, and MDR1 expression for RFS, and recurrence, age, and Ki-67 expression for OS. NAC responders with slightly decreased AI/V and increased MI/V had a poor prognosis.
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PMID:Neoadjuvant chemotherapy in cervical carcinoma: regulators of cell cycle, apoptosis, and proliferation as determinants of response to therapy and disease outcome. 1171 Jun 91

Fanconi anemia (FA) is a recessive genomic instability syndrome characterized by developmental defects, progressive bone marrow failure, and cancer. FA is genetically heterogeneous, however; the proteins encoded by different FA loci interact functionally with each other and with the BRCA1, BRCA2, and ATM gene products. Although patients with FA are highly predisposed to the development of myeloid leukemia and solid tumors, the alterations in biochemical pathways responsible for the progression of tumorigenesis in these patients remain unknown. FA cells are hypersensitive to a range of genotoxic and cellular stresses that activate signaling pathways mediating apoptosis. Here we show that ionizing radiation (IR) induces modestly elevated levels of p53 in cells from FA type C (Fancc) mutant mice and that inactivation of Trp53 rescues tumor necrosis factor alpha-induced apoptosis in myeloid cells from Fancc-/- mice. Further, whereas Fancc-/- mice failed to form hematopoietic or solid malignancies, mice mutant at both Fancc and Trp53 developed tumors more rapidly than mice mutant at Trp53 alone. This shortened latency was associated with the appearance of tumor types that are found in patients with FA but not in mice mutant at Trp53 only. Collectively, these data demonstrate that p53 and Fancc interact functionally to regulate apoptosis and tumorigenesis in Fancc-deficient cells.
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PMID:Fanconi anemia type C and p53 cooperate in apoptosis and tumorigenesis. 1285 57

Fanconi anemia is an autosomal recessive disorder characterized by congenital malformations, bone marrow failure, and the development of squamous cell carcinomas (SCCs) and other cancers. Recent clinicopathologic evidence has raised the possibility that an environmental factor such as human papillomavirus (HPV) may be involved in the pathogenesis of SCCs in Fanconi anemia patients. Given the high prevalence of p53 mutations in SCCs among the general population and the lack of p53 mutations in HPV-related carcinogenesis, we evaluated the role of HPV and p53 mutations and polymorphisms in SCC from Fanconi anemia patients. We used polymerase chain reaction (PCR) screening and real-time PCR to detect and quantify HPV DNA in DNA extracted from microdissected SCCs obtained from 24 Fanconi anemia patients (n = 25 SCCs; case subjects) and 50 age-, sex-, and tumor site-matched SCC patients without Fanconi anemia (n = 50 SCCs; control subjects). We PCR-amplified and sequenced exons 4-9 of the p53 gene from SCC DNA. We detected HPV DNA in 84% of the SCC specimens from the case subjects and in 36% of the SCC specimens from the control subjects (P<.001). The prevalence of p53 mutations in SCCs from the case subjects (0%, 0/25) was statistically significantly lower than that of SCCs from the control subjects (36%, 12/33; P<.001). A greater proportion of patients with Fanconi anemia and SCC were homozygous for Arg72, a p53 polymorphism that may be associated with increased risk for HPV-associated human malignancies, than an ethnically-matched cohort of Fanconi anemia patients without SCC (75% versus 51%; P =.05). These data suggest that Fanconi anemia is associated with increased susceptibility to HPV-induced carcinogenesis.
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PMID:Human papillomavirus DNA and p53 polymorphisms in squamous cell carcinomas from Fanconi anemia patients. 1519 19

Mechanisms underlying the multiple developmental defects observed in Fanconi anemia (FA) patients are not well defined. We have identified the zebrafish homolog of human FANCD2, which encodes a nuclear effector protein that is monoubiquitinated in response to DNA damage, targeting it to nuclear foci where it preserves chromosomal integrity. Fancd2-deficient zebrafish embryos develop defects similar to those found in children with FA, including shortened body length, microcephaly, and microophthalmia, which are due to extensive cellular apoptosis. Developmental defects and increased apoptosis in Fancd2-deficient zebrafish were corrected by injection of human FANCD2 or zebrafish bcl2 mRNA, or by knockdown of p53, indicating that in the absence of Fancd2, developing tissues spontaneously undergo p53-dependent apoptosis. Thus, Fancd2 is essential during embryogenesis to prevent inappropriate apoptosis in neural cells and other tissues undergoing high levels of proliferative expansion, implicating this mechanism in the congenital abnormalities observed in human infants with FA.
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PMID:Knockdown of zebrafish Fancd2 causes developmental abnormalities via p53-dependent apoptosis. 1466 12

This study was designed to investigate the possible relationship between the protein expression of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) with p53 status, breast cancer prognostic factors, metastatic site, and survival after adjuvant therapy. Basic fibroblast growth factor and VEGF expression were determined by enzyme-linked immunosorbent assays in cytosol specimens obtained from 1307 patients with T1-3 primary breast cancer (789 node-negative, 518 node-positive) diagnosed between 1990 and 1997. The median follow-up time was 70 months. Increased bFGF expression was more frequently found in tumors with low VEGF expression (r = -0.286; P = 0.095). Increased bFGF was associated with smaller tumors (P < 0.001), absence of axillary metastasis (P = 0.003), low S-phase fraction (P < 0.001), and longer recurrence-free survival (RFS; P = 0.0038) and overall survival (OS; P = 0.0316). Vascular endothelial growth factor was a prognostic factor for RFS (P < 0.0001) and OS (P < 0.0001) in univariate and multivariate analyses (RFS: 95% CI, 1.1-1.7; P = 0.036; OS: 95% CI, 1.2-2.2; P = 0.002), whereas bFGF expression was not correlated with RFS or OS. Increased VEGF content was correlated with shorter survival after adjuvant endocrine therapy (RFS, P = 0.0004; OS, P = 0.0009). Patients with estrogen receptor-negative disease were excluded from the analysis. Basic fibroblast growth factor was not a prognostic factor after adjuvant systemic therapy, nor was it related to metastatic site. Expression of VEGF is an independent prognostic factor for patients with primary breast cancer. High bFGF expression was related to good prognostic features and longer survival times, but did not add prognostic information in multivariate analysis. The results might implicate that different angiogenic pathways exist in human breast cancer.
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PMID:Prognostic correlation of basic fibroblast growth factor and vascular endothelial growth factor in 1307 primary breast cancers. 1471 9

Fanconi anemia (FA) is a complex, heterogeneous genetic disorder composed of at least 11 complementation groups. The FA proteins have recently been found to functionally interact with the cell cycle regulatory proteins ATM and BRCA1; however, the function of the FA proteins in cell cycle control remains incompletely understood. Here we show that the Fanconi anemia complementation group C protein (Fancc) is necessary for proper function of the DNA damage-induced G2/M checkpoint in vitro and in vivo. Despite apparently normal induction of the G2/M checkpoint after ionizing radiation, murine and human cells lacking functional FANCC did not maintain the G2 checkpoint as compared with wild-type cells. The increased rate of mitotic entry seen in Fancc-/-mouse embryo fibroblasts correlated with decreased inhibitory phosphorylation of cdc2 kinase on tyrosine 15. An increased inability to maintain the DNA damage-induced G2 checkpoint was observed in Fancc -/-; Trp53 -/-cells compared with Fancc -/-cells, indicating that Fancc and p53 cooperated to maintain the G2 checkpoint. In contrast, genetic disruption of both Fancc and Atm did not cooperate in the G2 checkpoint. These data indicate that Fancc and p53 in separate pathways converge to regulate the G2 checkpoint. Finally, fibroblasts lacking FANCD2 were found to have a G2 checkpoint phenotype similar to FANCC-deficient cells, indicating that FANCD2, which is activated by the FA complex, was also required to maintain the G2 checkpoint. Because a proper checkpoint function is critical for the maintenance of genomic stability and is intricately related to the function and integrity of the DNA repair process, these data have implications in understanding both the function of FA proteins and the mechanism of genomic instability in FA.
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PMID:A role for the Fanconi anemia C protein in maintaining the DNA damage-induced G2 checkpoint. 1537 54


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