Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

MDM4 is a key regulator of p53, whose biological activities depend on both transcriptional activity and transcription-independent mitochondrial functions. MDM4 binds to p53 and blocks its transcriptional activity; however, the main cytoplasmic localization of MDM4 might also imply a regulation of p53-mitochondrial function. Here, we show that MDM4 stably localizes at the mitochondria, in which it (i) binds BCL2, (ii) facilitates mitochondrial localization of p53 phosphorylated at Ser46 (p53Ser46(P)) and (iii) promotes binding between p53Ser46(P) and BCL2, release of cytochrome C and apoptosis. In agreement with these observations, MDM4 reduction by RNA interference increases resistance to DNA-damage-induced apoptosis in a p53-dependent manner and independently of transcription. Consistent with these findings, a significant downregulation of MDM4 expression associates with cisplatin resistance in human ovarian cancers, and MDM4 modulation affects cisplatin sensitivity of ovarian cancer cells. These data define a new localization and function of MDM4 that, by acting as a docking site for p53Ser46(P) to BCL2, facilitates the p53-mediated intrinsic-apoptotic pathway. Overall, our results point to MDM4 as a double-faced regulator of p53.
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PMID:MDM4 (MDMX) localizes at the mitochondria and facilitates the p53-mediated intrinsic-apoptotic pathway. 1952 40

Primary bone diffuse large B-cell lymphomas (PB-DLBCL) are uncommon extranodal lymphomas. Herein, we report the clinical, pathologic, immunohistochemical, and molecular features of 21 cases of PB-DLBCL. The mean age of the patients was 54 years (range: 13 to 85 y). The male and female ratio was 1.6:1. The tumors consisted of diffuse sheets of large atypical cells or a polymorphous mixture of small-to-large cells with large multilobated nuclei, fine chromatin, and inconspicuous to prominent nucleoli. Twelve (57%) cases were non-germinal center B (GCB) and 9 (43%) were GCB subtype based on immunohistochemical classification. B-cell lymphomas (BCL)-2 was positive in 17/21 (81%), TP53 in 11/21 (52%) positive and the mean MIB-1 index was 57%. Polymerase chain reaction showed 10 cases with immunoglobulin heavy-chain (IGH) and 4 cases with IGH/BCL-2 gene rearrangement. The fluorescence in-situ hybridization analyses showed 14% of cases with BCL-6, 19% of cases with BCL-2, and 9% of cases with C-MYC gene rearrangement. Age <60 years and complete response to initial treatment were significant predictors of survival outcome (P< or =0.05). Even though no association was observed between the subtype of PB-DLBCL (GCB vs. non-GCB), BCL2, TP53, MIB1 index and overall survival (P>0.05), due to small sample size, and variability in treatment received, this analysis may be interpreted with caution.
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PMID:Primary bone diffuse large B-cell lymphoma: clinicopathologic study of 21 cases and review of literature. 1967 54

p53 is a crucial regulator of cell response to DNA damage. MDM4 and MDM2 are the two main negative regulators of p53 activity. Upon DNA damage, their constraint is released and p53 becomes activated and exerts its safeguard function by arresting cell growth or by killing excessively damaged cells. Under these conditions, increasing data suggest that MDM4 and MDM2 play novel roles. In this respect, we recently published that MDM4 exerts a positive activity towards p53 mitochondrial apoptosis. We observed that a fraction of MDM4 stably localizes at the mitochondria where upon lethal stress conditions, promotes the mitochondrial localization of p53 phosphorylated at Ser46 (p53Ser46(P)) and facilitates its binding to BCL2, cytochrome C release and apoptosis. Most importantly, we observed a correlation of MDM4 expression with cisplatin-resistance in a group of human ovarian cancers suggesting that MDM4 proapoptotic activity may have in vivo relevance. Here, we discuss about these and some new findings and compare them with previous data trying to settle some apparent contradictions. In addition, this review discusses the potential relevance of our data to the field of human cancer.
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PMID:Mitochondrial MDM4 (MDMX): an unpredicted role in the p53-mediated intrinsic apoptotic pathway. 1988 11

The putative tumor suppressor miR145 is transcriptionally regulated by TP53 and is downregulated in many tumors; however, its role in prostate cancer is unknown. On the other hand, BCL2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3) is overexpressed in various tumors, including prostate cancer, and may transcriptionally repress the apoptosis-inducing factor (AIF) gene. Although BNIP3 transcription is controlled by hypoxia-inducible factor 1alpha (also elevated in prostate cancer), we postulated the posttranscriptional regulation of BNIP3 by miR145 through bioinformatics analysis, and herein we experimentally showed that miR145 negatively regulated BNIP3 by targeting its 3'-untranslated region. Artificial overexpression of miR145 by using adenoviral vectors in prostate cancer PC-3 and DU145 cells significantly downregulated BNIP3, together with the upregulation of AIF, reduced cell growth, and increased cell death. Artificial overexpression of wild-type TP53 in PC-3 cells (which lack TP53 protein) and DU145 cells (in which mutated nonfunctioning TP53 is expressed) significantly upregulated miR145 expression with consequent effects on BNIP3 and cell behavior as with miR145 overexpression. Analysis of prostate cancer (n = 134) and benign prostate (n = 83) tissue sample showed significantly decreased miR145 and increased BNIP3 expression in prostate cancer (P < 0.001), particularly in those with tumor progression, and both molecular changes were associated with unfavorable outcome. Abnormalities of the miR145-BNIP3 pair as part of TP53-miR145-BNIP3-AIF network may play a major role in prostate cancer pathogenesis and progression.
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PMID:MicroRNA145 targets BNIP3 and suppresses prostate cancer progression. 2033 43

The chronic usage of nifedipine is associated with the appearance of gingival overgrowth (GO). The frequency of GO associated with chronic nifedipine therapy remains controversial and the possible subclinical effects of this drug on the gingival epithelium should be investigated. We investigated the epithelial proliferation index and apoptosis rate, and their association with epithelial enlargement. Proliferation (Ki67 and Cyclin B1) and apoptosis (BCL2, Bax and p53) markers were identified by immunohistochemistry in twenty-one samples of gingival tissue from patients undergoing chronic treatment with nifedipine and in eleven samples of gingival tissue from healthy patients who did not use drugs associated with GO (control). Our results show that the epithelial tissue of nifedipine users has considerably longer rete pegs compared to control (P = 0.01). However, the density of Ki67(+) and Cyclin B1(+) cells was similar in both groups. Regarding apoptosis, we found more BCL2(+) cells in the nifedipine group when compared to controls (P = 0.12). An increase in Bax(+) cells in the nifedipine group compared to control (P = 0.003) was also seen, and slightly lower levels of p53(+) expression were observed (P = 0.51). Our results suggest that the chronic use of nifedipine is not associated with subclinical changes in gingival tissue.
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PMID:Long-term effects of nifedipine on human gingival epithelium: a histopathological and immunohistochemical study. 2033 33

Apoptosis-related proteins play an important role in lymphoma cell death during chemotherapy. In our study, we investigated the prognostic significance of CD95, BCL2, and P53 expression in extranodal non-Hodgkin's lymphoma (NHL). We examined 71 patients with extranodal NHL [45 diffuse large B-cell lymphomas (DLBCLs) and 26 mucosa-associated lymphoid tissue lymphomas (MALTLs)], 35 male and 36 female, with a median age of 65.8 years. The most common site of origin was the stomach (N = 31). Paraffin-embedded specimens were analyzed immunohistochemically for CD95, BCL2, and P53 expression. Multivariate analysis revealed that in DLBCLs, positive CD95 and negative BCL2 expression were independent prognostic factors for overall survival. We reached the same conclusion for MALTLs, with positive CD95 and negative P53 expression. In DLBCLs, the 5-year overall survival rate was 71.5% for the CD95-positive cases and 35% for the CD95-negative cases (p = 0.004) and the 5-year overall survival was significantly better in BCL2-negative cases (70.8%) when compared to BCL2-positive cases (37%; p = 0.009). In MALTLs, the 5-year overall survival rate for the CD95-positive and CD95-negative groups was 89.5% and 42.9%, respectively (p = 0.004) and the 5-year overall survival rate was 50% for the P53-positive cases and 88.9% for the P53-negative cases (p = 0.016). In conclusion, positive CD95 expression proved to be a good prognostic factor of overall survival in both extranodal DLBCLs and MALTLs. In contrast, positive expression of BCL2 and P53 was found to be unfavorably associated with survival in extranodal DLBCLs and MALTLs, respectively.
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PMID:Prognostic significance of CD95, P53, and BCL2 expression in extranodal non-Hodgkin's lymphoma. 2035 31

To explore the mechanism of apoptosis induced by cisplatin, the expression of microRNAs (miRNAs) and regulating genes in K562 cells was analyzed using reverse transcription PCR, quantitative real-time PCR and enzyme-linked immunosorbent assays. Our results showed that miR-16, miR-34a-c, miR-17-5p and miR-125 were up-regulated, and their associated oncogenes (BCL2, E2F1 and E2F3, respectively) were down-regulated after cisplatin treatment. We also showed that miR-106 and miR-150 were down-regulated while their target genes (RB1 and P53, respectively) were up-regulated after cisplatin treatment. Moreover, miR-16, miR-34a-c and miR-17-5p proved to be upstream factors, regulating the expression of BCL2, E2F1 and E2F3, respectively. The oncogene E2F3 was down-regulated when RB1 expression was increased after treatment with antisense oligonucleotides (ASO). Similarly, BCL2 and E2F3 were down-regulated when P53 expression was elevated by ASO treatment. The study demonstrated that cisplatin induces K562 cells to apoptosis by reducing miR-106 which up-regulates RB1 or by inhibiting miR-150 which increases P53 expression.
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PMID:miRNA-regulated expression of oncogenes and tumor suppressor genes in the cisplatin-inhibited growth of K562 cells. 2042 27

Genomic alterations play a crucial role in the development and progression of diffuse large B-cell lymphomas (DLBCLs). We determined gene copy number alterations (GCNAs) of TP53, CDKN2A, CDKN1B, BCL2, MYC, REL, and RB1 with a single polymerase chain reaction (PCR) assay (quantitative multiplex PCR of short fragments [QMPSF]) in a cohort of 114 patients with DLBCL to assess their prognostic value and relationship with the gene expression profile. Losses of TP53 and CDKN2A, observed in 8% and 35% of patients, respectively, were significantly associated with a shorter survival after rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) treatment, independently of the International Prognostic Index and of the cell of origin. Analysis of the 9p21 genomic region indicated that transcripts encoding p14ARF and p16INK4A were both disrupted in most patients with CDKN2A deletion. These patients predominantly had an activated B-cell profile and showed a specific gene expression signature, characterized by dysregulation of the RB/E2F pathway, activation of cellular metabolism, and decreased immune and inflammatory responses. These features may constitute the molecular basis sustaining the unfavorable outcome and chemoresistance of this DLBCL subgroup. Detection of TP53 and CDKN2A loss by QMPSF is a powerful tool that could be used for patient stratification in future clinical trials.
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PMID:Diffuse large B-cell lymphomas with CDKN2A deletion have a distinct gene expression signature and a poor prognosis under R-CHOP treatment: a GELA study. 2043 84

The 'p53 signature' is a benign secretory cell outgrowth in the distal Fallopian tube that shares properties with ovarian serous cancer-including p53 mutations-and is a putative serous cancer precursor. We expanded the precursor definition to all secretory cell outgrowths (SCOUTs) of 30 or more cells and scored normal (N) and altered (A) expression of both p53 and PAX2, a gene down-regulated in ovarian and endometrial cancer. SCOUTs were identified by BCL2/p73 staining in tubes from women with serous carcinoma, inherited mutations in BRCA1 or BRCA2 and controls. SCOUTs were prevalent in both proximal and distal tube and significantly associated with serous carcinoma versus the others (p < 0.001); 89% were PAX2 (A) and 26% were PAX2 (A)/p53 (A) (p53 signatures). PAX2 (A)/p53 (N) SCOUTs were free of p53 mutations; however, 12 of 13 p53 signatures were PAX2 (A). A tubal carcinoma and contiguous SCOUT were p53 (A)/PAX2 (A) and shared the same p53 mutation. SCOUTs are discretely localized alterations commonly containing altered expression of multiple genes within histologically benign tubal epithelium. Geographic distribution in the tube varies by genotype and immunophenotype, from regionally unrestricted (PAX2) to greater likelihood specific area (fimbria) of shared prevalence (PAX2 and p53). This study reveals, for the first time, an entity (SCOUT) that is associated with serous cancer, expands the topography of altered PAX2 expression in the female genital tract mucosa and highlights another potential pathway disturbance involved in early serous carcinogenesis in the Fallopian tube.
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PMID:Secretory cell outgrowth, PAX2 and serous carcinogenesis in the Fallopian tube. 2059 68

Superb biological effectiveness and dose conformity represent a rationale for heavy-ion therapy, which has thus far achieved good cancer controllability while sparing critical normal organs. Immediately after irradiation, heavy ions produce dense ionization along their trajectories, cause irreparable clustered DNA damage, and alter cellular ultrastructure. These ions, as a consequence, inactivate cells more effectively with less cell-cycle and oxygen dependence than conventional photons. The modes of heavy ion-induced cell death/inactivation include apoptosis, necrosis, autophagy, premature senescence, accelerated differentiation, delayed reproductive death of progeny cells, and bystander cell death. This paper briefly reviews the current knowledge of the biological aspects of heavy-ion therapy, with emphasis on the authors' recent findings. The topics include (i) repair mechanisms of heavy ion-induced DNA damage, (ii) superior effects of heavy ions on radioresistant tumor cells (intratumor quiescent cell population, TP53-mutated and BCL2-overexpressing tumors), (iii) novel capacity of heavy ions in suppressing cancer metastasis and neoangiogenesis, and (iv) potential of heavy ions to induce secondary (especially breast) cancer.
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PMID:Recent advances in the biology of heavy-ion cancer therapy. 2067 39


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