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)

BAG-1 is an anti-apoptotic protein that interacts with Bcl-2, Bcl-XL, Hsp70/Hsc70, Raf-1 and numerous hormone or growth factor receptors. Recently, BAG-1 has been found to be overexpressed in a variety of human cancer cell lines and some tumors. However, the molecular mechanism of BAG-1 upregulation is still unclear. In this study, we cloned 0.9 kb of human genomic DNA, BGEV, 5' flanking the BAG-1 open reading frame. BGEV subcloned into a promoterless luciferase reporter vector conferred high promoter activity in various human cancer cell lines. Deletion analysis of this sequence localized the region of maximal BAG-1 promoter activity from nucleotide positions -353 to -54, upstream of the first start codon CTG. Sequence analysis of the BAG-1 promoter region showed the absence of a TATA box but identified a CCAAT box, several GC boxes, a CpG island and several transcriptional factor binding sites, which may be important in the regulation of BAG-1 transcription. Most importantly, functional characterization of the BAG-1 promoter in vivo demonstrated that gain-of-function p53 mutants derived from human tumors upregulated the transcription of BAG-1 RNA and the expression of a reporter gene from the BAG-1 promoter. These results indicated that we have isolated the functional constitutive BAG-1 promoter. Furthermore, the data suggested that overexpression of BAG-1 in some tumors may be due to upregulation of the human BAG-1 promoter by mutant p53.
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PMID:Cloning and characterization of the human BAG-1 gene promoter: upregulation by tumor-derived p53 mutants. 1046 99

The proportions of aneuploid/polyploid versus euploid cells formed after treatment with spindle poisons like nocodazole are of course dependent on the relative survival of cells with numerical chromosome aberrations. This work aimed at studying the survival of polyploid cells formed after treatment with a nocodazole concentration sufficient to significantly decrease tubulin polymerization (0.1 microg/ml). First, normal primary lymphocytes were analysed and the following complementary chromosomal parameters were quantified: mitotic index, frequency of abnormal mitoses, polyploid metaphases and apoptotic cells. The results clearly indicate a positive correlation between abnormal mitotic figures, apoptosis and the induction of polyploidy. They therefore led to a single cell approach in which both apoptosis and polyploidy induction could be scored in the same cell. For this purpose, actively proliferating cells are required and two human leukaemic cell lines were used, KS (p53-positive) and K562 (p53-negative), which have a near-triploid karyotype. Cells were separated into an apoptotic and a viable fraction by means of annexin-V staining and flow cytometry. In KS, treatment with nocodazole induced a similar fraction of hexaploid cells in both the viable and apoptotic fraction, but no dodecaploid cells were ever observed. In contrast, a population of dodecaploid cells (essentially viable) was clearly observed in the K562 cell line. The results in KS, as compared with K562, confirm that wild-type p53 can prevent further cycling of polyploid cells by blocking rereplication. The most probable explanation for these data is that not only the mitotic spindle but also interphase microtubules are sensitive to nocodazole treatment. Our data thus strongly suggest that besides the G(1)/S checkpoint under the control of p53, the G(2)/M transition may be sensitive to depolymerization of microtubules, possibly under the control of Cdc2, Bcl-2, Raf-1 and/or Rho.
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PMID:Induction of polyploidy and apoptosis after exposure to high concentrations of the spindle poison nocodazole. 1047 56

Inhibition of apoptosis is an important characteristic of oncogenic transformation. The Par-4 gene product has recently been shown to be upregulated in cells undergoing apoptotic cell death, and its ectopic expression was shown to be critical in apoptosis. We demonstrate that expression of oncogenic Ras promotes a potent reduction of Par-4 protein and mRNA levels through a MEK-dependent pathway. In addition, the expression of permanently active mutants of MEK, Raf-1 or zetaprotein kinase C but not of phosphatidylinositol 3-kinase (PI 3-kinase) is sufficient to decrease Par-4 levels. These effects are independent of p53, p16 and p19, and were detected not only in fibroblast primary cultures but also in NIH 3T3 and HeLa cells, indicating that they are not secondary to Ras actions on cell cycle regulation. Importantly, restoration of Par-4 levels to normal in Ras-transformed cells makes these cells sensitive to the pro-apoptotic actions of tumor necrosis factor-alpha under conditions in which PI 3-kinase is inhibited and also severely impairs colony formation in soft agar and tumor development in nude mice, as well as increases the sensitivity of these tumors to camptothecin. This indicates that the downregulation of Par-4 by oncogenic Ras is a critical event in tumor progression.
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PMID:The downregulation of the pro-apoptotic protein Par-4 is critical for Ras-induced survival and tumor progression. 1056 48

We have recently reported that there is a significant Raf-1 kinase dependency of paclitaxel resistance in human cervical tumor cell lines. In light of the possibility that Raf-1 kinase inhibitors could be used to enhance paclitaxel responsiveness in ovarian cancer, we have characterized the Raf-1 kinase dependency of paclitaxel resistance in ovarian cancer cells. The relationship between Raf-1 kinase activity and the sensitivity to clinically relevant paclitaxel concentrations was determined in four ovarian cancer cell lines (CA-OV3, SK-OV3, 2780/WT and OAW42/WT). Furthermore, in recognition that such a drug combination would initially be used in patients whose tumors have recurred following cisplatin/paclitaxel treatment, we also determined the Raf-1 kinase dependency of paclitaxel cytotoxicity in cisplatin resistant variants of two of the ovarian cell lines (2780/CP and OAW42/CP). In the two cell lines (2780/WT and OAW42/WT) that possess a wild-type TP53 (TP53wt), the relationship between Raf-1 kinase activity and paclitaxel resistance was different from that observed in the cervical tumor cell lines. In these cell lines, paclitaxel-induced far more cell killing than would have been predicted from their Raf-1 kinase activity. However, in the ovarian cancer cell lines (CA-OV3, SK-OV3, 2780/CP and OAW42/CP) that have a mutant TP53 (TP53mut), the cytotoxicity induced by 60 nM paclitaxel exhibited the same relationship to Raf-1 kinase activity as previously observed in cervical tumor cell lines. These data suggest that the therapeutic efficacy of paclitaxel in ovarian cancer patient whose tumors have TP53mut might be increased if it is administered in combination with Raf-1 kinase inhibitors, e.g., ISIS 5132.
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PMID:Raf-1 kinase activity predicts for paclitaxel resistance in TP53mut, but not TP53wt human ovarian cancer cells. 1085 51

The tumour suppressor gene, p53, and genes coding for positive signal transduction factors can influence transit through cell-cycle checkpoints and modulate radiosensitivity. Here we examine the effects of RAF1 protein on the rate of exit from a G2/M block induced by gamma-irradiation in relation to intrinsic cellular radiosensitivity in human cell lines expressing wild-type p53 (wtp53) protein as compared to mutant p53 (mutp53) protein. Cell lines which expressed mutp53 protein were all relatively radioresistant and exhibited no relationship between RAF1 protein and cellular radiosensitivity. Cell lines expressing wtp53 protein, however, showed a strong relationship between RAF1 protein levels and the radiosensitivity parameter SF2. In addition, when post-irradiation perturbation of G2/M transit was compared using the parameter T50 (time after the peak of G2/M delay at which 50% of the cells had exited from a block induced by 2 Gy of irradiation), RAF1 was related to T50 in wtp53, but not mutp53, cell lines. Cell lines which expressed wtp53 protein and high levels of RAF1 had shorter T50s and were also more radiosensitive. These results suggest a cooperative role for wtp53 and RAF1 protein in determining cellular radiosensitivity in human cells, which involves control of the G2/M checkpoint.
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PMID:Combined RAF1 protein expression and p53 mutational status provides a strong predictor of cellular radiosensitivity. 1099 58

Normal human fibroblasts have been shown to undergo a p16(Ink4a)-associated senescence-like growth arrest in response to sustained activation of the Ras/Raf/MEK/ERK pathway. We noted a similar p16(Ink4a)-associated, senescence-like arrest in normal human astrocytes in response to expression of a conditional form of Raf-1. While HPV16 E7-mediated functional inactivation of the p16(Ink4a)/pRb pathway in astrocytes blocked the p16(Ink4a)-associated growth arrest in response to activation of Raf-1, it also revealed a second p21(Cip1)-associated, senescence-associated, beta-galactosidase-independent growth arrest pathway. Importantly, the p21(Cip1)-associated pathway was present not only in normal astrocytes but also in p53-, p14(ARF)-, and p16(Ink4a)/pRb-deficient high grade glioma cells that lacked the p16(Ink4a)-dependent arrest mechanism. These results suggest that normal human cells have redundant arrest pathways, which can be activated by Raf-1, and that even tumors that have dismantled p16(Ink4a)-dependent growth arrest pathways are potentially regulated by a second p21(Cip1)-dependent growth arrest pathway.
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PMID:Dual growth arrest pathways in astrocytes and astrocytic tumors in response to Raf-1 activation. 1127 20

The p53-regulated stress-inducible gene GADD45 has been shown to participate in cellular response to DNA damage, including cell cycle checkpoint, apoptosis, and DNA repair. However, the regulation of GADD45 expression is complex and may involve both p53-dependent and -independent pathways. Recent findings have demonstrated that the p53-independent induction of GADD45 is mainly regulated by the transcription factors Oct-1 and NF-YA, which directly bind to their consensus motifs located at the GADD45 promoter region. Here, we report that mitogen-activated protein (MAP) kinases are involved in the induction of the GADD45 promoter after DNA damage. Inhibition of JNK1 and ERK kinase activities either by expression of the dominant negative mutant JNK1 or by treatment with a selective chemical inhibitor of ERK (PD098059) substantially abrogates the UV induction of the GADD45 promoter. In contrast, a p38 kinase inhibitor (SB203580) has little effect on GADD45 induction by UV. In addition, the GADD45 promoter is strongly activated following expression of JNK1; Raf-1, which is an upstream activator of the ERK pathway; or MEK1, an upstream activator of both the ERK and the JNK pathways. Activation of the GADD45 promoter by MAP kinases does not require normal p53 function. Interestingly, the MAP kinase-regulatory effect appears to be mediated via OCT-1 and CAAT motifs since disruption of these sites abrogates activation of the GADD45 promoter by MAP kinases. Therefore, these findings indicate that the MAP kinase pathways are involved in the regulation of the p53-independent induction of the GADD45 promoter, probably via interaction with transcription factors that directly bind to OCT-1 and CAAT motifs.
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PMID:Involvement of the MAP kinase pathways in induction of GADD45 following UV radiation. 1152 40

Heat shock protein 90 (Hsp90) is a molecular chaperone whose association is required for the stability and function of multiple mutated, chimeric and over-expressed signaling proteins that promote the growth and/or survival of cancer cells. Hsp90 client proteins include mutated p53, Bcr-Abl, Raf-1, Akt, ErbB2 and hypoxia-inducible factor 1 alpha (HIF-1 alpha). Hsp90 inhibitors, by interacting specifically with a single molecular target, cause the destabilization and eventual degradation of Hsp90 client proteins, and they have shown promising antitumor activity in preclinical model systems. One Hsp90 inhibitor, 17-allylaminogeldanamycin (17AAG), is currently in phase I clinical trial. Because of the chemoprotective activity of several proteins that are Hsp90 clients, the combination of an Hsp90 inhibitor with a standard chemotherapeutic agent could dramatically increase the in vivo efficacy of the therapeutic agent.
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PMID:Hsp90 inhibitors as novel cancer chemotherapeutic agents. 1192 89

Gene expression profiling with cDNA array allows simultaneous analysis of the gene expression pattern of a large number of genes and may enhance the investigation of the molecular mechanisms involved in the treatment of hepatocellular carcinoma with cisplatin. We used cDNA array technology to assess the gene expression profiles related to cell cycle regulation and apoptosis in human hepatoma Hep3B cells in response to cisplatin treatment. In Hep3B cells, apoptosis induced by cisplatin was p53-independent, and was associated with up-regulation of cell cycle regulators, pro-apoptotic genes, growth receptors, and genes involved in signal transduction. These included p33ING1, c-Abl, Bax, insulin-like growth factor binding protein 3, Siva, cyclin D1, RhoA, and Raf-1. Down-regulation of cell cycle regulator CDC2 was observed. Semi-quantitative reverse transcription-polymerase chain reaction and/or Western blot analysis performed on seven of these genes confirmed their upregulation of gene expression. Such global analysis of the cytotoxic response to chemotherapeutic drugs may yield insight into the mechanisms of drug action and allow rational design of more effective treatment strategies.
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PMID:Gene expression profiling by cDNA array in human hepatoma cell line in response to cisplatin treatment. 1199 Dec 55

We studied the roles of the phosphatidylinositol 3-kinase (PI-3K)-Akt-BAD cascade, ERK-BAD cascade, and Akt-Raf-1 cascade in the paclitaxel-resistant SW626 human ovarian cancer cell line, which lacks functional p53. Treatment of SW626 cells with paclitaxel activates Akt and ERK with different time frames. Interference with the Akt cascade either by treatment with PI-3K inhibitor (wortmannin or LY294002) or by exogenous expression of a dominant negative Akt in SW626 cells caused decreased cell viability following treatment with paclitaxel. Interference with the ERK cascade by treatment with an MEK inhibitor, PD98059, in SW626 cells also caused decreased cell viability following treatment with paclitaxel. Treatment of cells with paclitaxel also stimulated the phosphorylation of BAD at both the Ser-112 and Ser-136 sites. The phosphorylation of BAD at Ser-136 was blocked by treatment with wortmannin or cotransfection with the dominant negative Akt. On the other hand, the phosphorylation of BAD at Ser-112 was blocked by PD98059. We further examined the role of BAD in the viability following paclitaxel treatment using BAD mutants. Exogenous expression of doubly substituted BAD2SA in SW626 cells caused decreased viability following treatment with paclitaxel. Moreover, because paclitaxel-induced apoptosis is mediated by activated Raf-1 and the region surrounding Ser-259 in Raf-1 conforms to a consensus sequence for phosphorylation by Akt, the regulation of Raf-1 by Akt was examined. We demonstrated an association between Akt and Raf-1 and showed that the phosphorylation of Raf-1 on Ser-259 induced by paclitaxel was blocked by treatment with wortmannin or LY294002. Furthermore, interference with the Akt cascade induced by paclitaxel up-regulated Raf-1 activity, and expression of constitutively active Akt inhibited Raf-1 activity, suggesting that Akt negatively regulates Raf-1. Our findings suggest that paclitaxel induces the phosphorylation of BAD Ser-112 via the ERK cascade, and the phosphorylation of both BAD Ser-136 and Raf-1 Ser-259 via the PI-3K-Akt cascade, and that inhibition of either of these cascades sensitizes ovarian cancer cells to paclitaxel.
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PMID:Inhibition of phosphorylation of BAD and Raf-1 by Akt sensitizes human ovarian cancer cells to paclitaxel. 1208 97


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