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)

AML1/RUNX1 mutations have been reported frequently in myelodysplastic syndrome (MDS) patients, especially those diagnosed with refractory anemia with excess blast (RAEB), RAEB in transformation (RAEBt), or AML following MDS (these categories are defined as MDS/AML). Although AML1 mutations are suspected to play a pivotal role in the development of MDS/AML, acquisition of additional genetic alterations is also necessary. We analyzed gene alterations in MDS/AML patients with AML1 mutations, comparing them to alterations in those without an AML1 mutation. AML1 mutations were significantly associated with -7/7q-, whereas MDS/AML patients without AML1 mutations showed a high frequency of -5/5q- and a complex karyotype. Patients with AML1 mutations showed more mutations of their FLT3, N-RAS, PTPN11, and NF1 genes, resulting in a significantly higher mutation frequency for receptor tyrosine kinase (RTK)-RAS signaling pathways in AML1-mutated MDS/AML patients compared to AML1-wild-type MDS/AML patients (38% versus 6.3%, P < 0.0001). Conversely, p53 mutations were detected only in patients without AML1 mutations. Furthermore, blast cells of the AML1-mutated patients expressing surface c-KIT, and SHP-2 mutants contributed to prolonged and enhanced extracellular signal-regulated kinase activation following stem cell factor stimulation. Our results suggest that MDS/AML arising from AML1/RUNX1 mutations has a significant association with -7/7q- alteration, and frequently involves RTK-RAS signaling pathway activation.
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PMID:Hyperactivation of the RAS signaling pathway in myelodysplastic syndrome with AML1/RUNX1 point mutations. 1646 64

Epidermal melanocytes execute specific physiological programs in response to UV radiation (UVR) at the cutaneous interface. Many melanocytic responses, including increased dendrite formation, enhanced melanogenesis/melanization, and cell cycle arrest impact the ability of melanocytes to survive and to attenuate the UVR insult. Although some of the molecules that underlie these UVR programs are known, a coherent view of UVR-induced transcriptional changes is lacking. Using primary melanocyte cultures, we assessed for UVR-mediated alterations in over 47,000 transcripts using Affymetrix Human Genome U133 Plus 2.0 microarrays. From the 100 most statistically robust changes in transcript level, there were 84 genes that were suppressed >2.0-fold by UVR; among these transcripts, the identities of 48 of these genes were known. Similarly, there were 99 genes that were induced >2.0-fold by UVR; the identity of 57 of these genes were known. We then subjected these top 100 changes to the Ingenuity Pathway analysis program and identified a group of p53 targets including the cell cycle regulator CDKN1A (p21CIP), the WNT pathway regulator DKK1 (dickkopf homolog 1), the receptor tyrosine kinase EPHA2, growth factor GDF15, ferrodoxin reductase (FDXR), p53-inducible protein TP53I3, transcription factor ATF3, DNA repair enzyme DDB2, and the beta-adrenergic receptor ADBR2. These genes were also found to be consistently elevated by UVR in six independent melanocyte lines, although there were interindividual variations in magnitude. WWOX, whose protein product interacts and regulates p53 and p73, was found to be consistently suppressed by UVR. There was also a subgroup of neurite/axonal developmental genes that were altered in response to UVR, suggesting that melanocytic and neuronal arborization may share similar mechanisms. When compared to melanomas, the basal levels of many of these p53-responsive genes were greatly dysregulated. Three genes--CDKN1A, DDB2 and ADRB2--exhibited a trend towards loss of expression in melanomas thereby raising the possibility of a linked role in tumorigenesis. These expression data provide a global view of UVR-induced changes in melanocytes and, more importantly, generate novel hypotheses regarding melanocyte physiology.
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PMID:Expression profiling of UVB response in melanocytes identifies a set of p53-target genes. 1688 33

Small-cell lung cancer accounts for up to one-fifth of all lung cancers diagnosed. While the response rates to chemotherapy are high, ultimately the majority of patients will relapse and die from their disease. Long-term outcomes are poor. A number of new agents and novel strategies for the treatment of small-cell lung cancer are under evaluation, and this review outlines the current most promising agents and pivotal trials. Oblimersen, an antisense oligonuclide to the oncogene bcl-2, has been safely combined with chemotherapy. The proteosome inhibitor bortezomib has not demonstrated single-agent activity in phase II trials but is now being evaluated with proapoptotic triggers. A number of anti-angiogenic strategies have been evaluated in small-cell lung cancer. The vascular endothelial growth factor (VEGF) antibody bevacizumab and a number of VEGF receptor tyrosine kinase inhibitors are in the early phases of clinical trials. Results from trials have not demonstrated any survival advantage with the addition of matrix metalloproteinase inhibitors. A phase III trial has reported improvements in median survival with the addition of thalidomide to chemotherapy, but toxicity has been problematic. Immunotherapy with p53 vaccines and BEC2 antibodies have shown some promise and require further evaluation to determine whether humoral responses can predict for response. Trials with the immunoconjugate BB-10901 and temirolimus are ongoing.
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PMID:Novel therapies for the treatment of small-cell lung cancer: a time for cautious optimism? 1710 Apr 4

Whether ErbB2 receptor tyrosine kinase contributes to cervical cancer is controversial. We have examined the effects of E6 and E7 genes of human papillomaviruses type 16 (HPV-16) on ErbB2 expression in primary human cervical keratinocytes (HCK) immortalized with hTERT (HCK1T). In E6-positive cells (HCK1T-E6 and HCK1T-E6E7), ErbB2 expression levels increased with the cell density. HCK1T-E6E7 showed impaired contact inhibition and anchorage-independent growth in soft agar which were abrogated with introduction of ErbB2-specific short hairpin RNA (shRNA) or an ErbB2 specific inhibitor AG825. Furthermore, increased ErbB2 expression was also observed in HPV16 positive cervical cancer cell lines and this was diminished by introduction of HPV16E6- or E6AP-shRNA. At post-confluence cell densities, ErbB2 protein was stabilized in the presence of E6 whereas increased ErbB2 expression was not obvious with E6 mutants incapable of degrading p53. Furthermore, introduction of p53-shRNA to HCK1T resulted in increased ErbB2 protein stability, indicating possible ErbB2 regulation through p53. Finally, we showed that tumor formation of ErbB2-shRNA introduced SiHa cells were almost abolished. Taken together, these data indicate an important role of ErbB2 regulation by HPV16 E6 in oncogenic transformation of human cervical keratinocytes.
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PMID:HPV16 E6-mediated stabilization of ErbB2 in neoplastic transformation of human cervical keratinocytes. 1714 42

During development and tissue homeostasis, cells must integrate different signals. We investigated how cell behavior is controlled by the combined activity of transforming growth factor-beta (TGF-beta) and receptor tyrosine kinase (RTK) signaling, whose integration mechanism is unknown. We find that RTK/Ras/MAPK (mitogen-activated protein kinase) activity induces p53 N-terminal phosphorylation, enabling the interaction of p53 with the TGF-beta-activated Smads. This mechanism confines mesoderm specification in Xenopus embryos and promotes TGF-beta cytostasis in human cells. These data indicate a mechanism to allow extracellular cues to specify the TGF-beta gene-expression program.
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PMID:Integration of TGF-beta and Ras/MAPK signaling through p53 phosphorylation. 1723 15

c-Abl non-receptor tyrosine kinase has been implicated in many cellular processes including cell differentiation, stress response and regulating gene transcription. The mechanism by which c-Abl is involved in the regulation of gene transcription remains to be elucidated. In this study, we investigated the functions of c-Abl in the activation of p21 promoter. Our results showed that overexpression of c-Abl tyrosine kinase activated p21 promoter and endogenous p21 transcription in U2OS cells. We found that p53 is involved in the activation of p21 promoter by c-Abl, and integrative structure of p53 is required for regulating p21 transcription. In addition, the chromatin immunoprecipitation study demonstrated that c-Abl and p53 can be recruited to the region containing p53 binding site of p21 promoter, and c-Abl increases the DNA binding activity of p53 to the p21 promoter. Furthermore, not only the activation of p21 promoter but also the recruitment to p21 promoter by c-Abl is dependent on the interaction between c-Abl and p53 protein.
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PMID:c-Abl tyrosine kinase activates p21 transcription via interaction with p53. 1733 30

Friend erythroleukemia virus has long served as a paradigm for the study of the multistage progression of leukemia. Friend virus infects erythroid progenitor cells, followed by an initial polyclonal expansion of infected cells, which is driven by the activation of a naturally occurring truncated form of the Stk receptor tyrosine kinase (Sf-Stk). Subsequently, the accumulation of additional mutations in p53 and the activation of PU.1 result in full leukemic transformation. The early stages of transformation induced by Friend virus are characterized in vitro by the Epo-independent growth of infected erythroblasts. We have shown previously that this transforming event requires the kinase activity and Grb2 binding site of Sf-Stk and the recruitment of a Grb2/Gab2 complex to Sf-Stk. Here, we demonstrate that Stat3 is required for the Epo-independent growth of Friend virus-infected cells and that the activation of Stat3 by Sf-Stk is mediated by a novel Stat3 binding site in Gab2. These results underscore a central role for Stat3 in hematopoietic transformation and describe a previously unidentified role for Gab2 in the recruitment and activation of Stat3 in response to transforming signals generated by tyrosine kinases.
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PMID:A novel Stat3 binding motif in Gab2 mediates transformation of primary hematopoietic cells by the Stk/Ron receptor tyrosine kinase in response to Friend virus infection. 1735 74

One of the physiologic consequences of excessive UV radiation (UVR) exposure is apoptosis. This critical response serves to eliminate genetically injured cells and arises, in part, from activation of DNA damage and p53 signaling. Other contributory pathways, however, likely exist but have not been fully characterized. In a recent global screen of UVR response genes in melanocytes, we identified the receptor tyrosine kinase EPHA2. Using a combination of genetic and pharmacologic approaches, we set out to investigate the upstream regulation of EphA2 by UVR and the functional consequences of this effect. We found that the UVR-associated increase in EphA2 occurs in melanocytes, keratinocytes, and fibroblasts from both human and murine sources. More specifically, UVR effectively up-regulated EphA2 individually in p53-null, p63-null, and p73-null murine embryonic fibroblasts (MEF), suggesting that the p53 family of transcription factors is not essential for the observed effect. However, inhibition of mitogen-activated protein kinase (MAPK) signaling by U0126 and PD98059 significantly reduced the UVR response whereas overexpression of oncogenic NRAS led to an increase in EphA2. These results confirm that UVR induces EphA2 by a p53-independent, but MAPK-dependent, mechanism. In response to UV irradiation, Epha2(-/-) MEFs were highly resistant to UVR-mediated cytotoxicity and apoptosis whereas introduction of EphA2 into both wild-type and p53-null MEFs led to activation of an apoptotic program that can be blocked by caspase-8 inhibition. These functional findings suggest that EphA2 is in fact an essential p53-independent, caspase-8-dependent proapoptotic factor induced by UVR.
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PMID:EphA2 is an essential mediator of UV radiation-induced apoptosis. 1833 48

MUC1, a transmembrane mucin, is a key modulator of several signaling pathways that affect oncogenesis, motility, and cell morphology. The interaction of MUC1 cytoplasmic tail (MUC1CT) with signal transducers and its nuclear translocation and subsequent biological responses are believed to be regulated by phosphorylation status, but the precise mechanisms by which this occurs remain poorly defined. We detected a novel association between the Met receptor tyrosine kinase and the MUC1CT. Met catalyzed phosphorylation of tyrosine at YHPM in the MUC1CT. Stimulation of S2-013.MUC1F pancreatic cancer cells with hepatocyte growth factor facilitated nuclear localization of MUC1CT, as determined by real time confocal imaging analysis. MUC1 overexpression also facilitated faster turnover of Met. Phosphorylation of MUC1CT by Met enhanced its interaction with p53, which led to suppression of AP1 transcription factor activity through interactions at the MMP1 promoter, ultimately leading to reduced transcription of MMP1. This correlated with a decrease in hepatocyte growth factor-induced invasiveness when MUC1 was overexpressed. The results demonstrate that MUC1 modulates Met-mediated oncogenic signaling in cancer.
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PMID:Phosphorylation of MUC1 by Met modulates interaction with p53 and MMP1 expression. 1862 14

Abnormal activation of DNA repair pathways by deregulated signaling of receptor tyrosine kinase systems is a compelling likelihood with significant implications in both cancer biology and treatment. Here, we show that due to a potential substrate switch, mutated variants of the receptor for hepatocyte growth factor Met, but not the wild-type form of the receptor, directly couple to the Abl tyrosine kinase and the Rad51 recombinase, two key signaling elements of homologous recombination-based DNA repair. Treatment of cells that express the mutated receptor variants with the Met inhibitor SU11274 leads, in a mutant-dependent manner, to a reduction of tyrosine phosphorylated levels of Abl and Rad51, impairs radiation-induced nuclear translocation of Rad51, and acts as a radiosensitizer together with the p53 inhibitor pifithrin-alpha by increasing cellular double-strand DNA break levels following exposure to ionizing radiation. Finally, we propose that in order to overcome a mutation-dependent resistance to SU11274, this aberrant molecular axis may alternatively be targeted with the Abl inhibitor, nilotinib.
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PMID:Coupling of mutated Met variants to DNA repair via Abl and Rad51. 1863 30


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