Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During terminal differentiation of human and murine cells, telomerase activity and parallel transcription of telomerase reverse transcriptase (hTERT) are inhibited. In this study, we used in vitro and in vivo analyses to determine the role of hTERT promoter elements and associated factors during differentiation-induced inhibition of telomerase expression in RD, a human rhabdomyosarcoma cell line. Assay of telomerase enzyme activity, hTERT mRNA, and reporter gene assays confirmed that the hTERT promoter was silenced during 12-O-tetradecanoylphorbol-13-acetate-induced myogenic differentiation of telomerase-positive RD cells. Promoter deletion and mutation analyses revealed that two E-boxes and an AP-2 site present in a 320-bp region of the promoter were essential for the transcriptional activity of the hTERT gene. Electrophoretic mobility shift assays identified several factors that interact with this region of DNA, including the muscle-specific transcription factors Myf5, Myf6, and myogenin and the ubiquitously expressed factors Sp1 and AP-2. Ectopic expression of the E-box binding factors c-Myc and Mad did influence promoter activity in these cells; indeed, the presence of endogenous c-Myc protein was altered after differentiation. Our findings suggest that the acute regulation of hTERT transcription is primarily controlled by E-box elements, which bind a series of factors during the phased phenotypic changes occurring during the differentiation of RD human muscle cells.
Mol Cancer Res 2003 Aug
PMID:Telomerase reverse transcriptase promoter regulation during myogenic differentiation of human RD rhabdomyosarcoma cells. 1293 99

We compared the extent to which apoptosis is induced and clonogenicity reduced in three tumour cell lines - the human melanoma Me45 and promyelocytic leukaemia HL-60, and the rat rhabdomyosarcoma R1 - after exposure to the anticancer drugs etoposide and cis-platinum or to gamma radiation; each induces different types of DNA damage. Cells which readily underwent apoptosis did not necessarily show a correlated loss of clonogenicity; for example, Me45 cells showed the highest sensitivity to all three agents in clonogenic assays but much lower levels of apoptotic cells than R1 or HL-60 cells. These results show that the efficiency of the eradication of clonogenic cells by genotoxic agents does not solely depend on the induction of apoptotic processes, and suggest that the induction of apoptosis and suppression of clonogenicity are independent processes.
Cell Mol Biol Lett 2003
PMID:Apoptosis and clonogenic survival in three tumour cell lines exposed to gamma rays or chemical genotoxic agents. 1294 6

The diagnosis of small round cell sarcomas is often very difficult, especially when only small biopsy specimens are available for examination. Recent studies have shown that some sarcomas have specific recurrent chromosomal translocations producing chimeric gene fusions, which can be detected by reverse transcription-polymerase chain reaction (RT-PCR), fluorescent in situ hybridization (FISH), or cytogenetic analysis. In this study, 12 cases of well-defined sarcomas including Ewings sarcoma/primitive neuroectodermal tumors (ES/PNET), synovial sarcoma (SS), alveolar rhabdomyosarcoma (ARMS), and desmoplastic small round cell tumors (DSRCT) were used to collect specific numbers of cells by laser capture microdissection (LCM), subsequently used for RT-PCR to detect specific chimeric gene transcripts. Tumor cells from fresh-frozen (FS) tissue sections and paraffin-embedded (PS) tissue sections from the same cases were compared directly to evaluate the sensitivity of FS and PS sections as the starting material for analysis. Samples were used for RNA extraction, RT-PCR analysis, and Southern hybridization with fluorescein-labeled internal probes followed by enhance chemiluminescence (ECL) detection. The fusion gene transcripts could be detected using 50 cells from FS materials in all cases and from 1 cell in 9 of 12 cases. For PS, a positive signal could be detected using 200 to 1000 cells in all cases, while weaker signals were detected using 50 cells in most cases. These results indicate that the fusion gene products from small round cell sarcomas can be detected by RT-PCR with 10 to 200 cells from FS and PS tissues. The sensitivity of RT-PCR with FS was 10- to 50-fold greater than with PS. These results also suggest that RT-PCR analysis for sarcoma fusion gene products can be successfully performed when only a few cells are available for analysis, although this is not recommended for routine clinical use.
Diagn Mol Pathol 2003 Dec
PMID:Detection of fusion gene transcripts in fresh-frozen and formalin-fixed paraffin-embedded tissue sections of soft-tissue sarcomas after laser capture microdissection and rt-PCR. 1463 8

Previously it has been reported that caveolin-1 (cav-1) has antiapoptotic activities in prostate cancer cells and functions downstream of androgenic stimulation. In this study, we demonstrate that cav-1 overexpression significantly reduced thapsigargin (Tg)-stimulated apoptosis. Examination of the phosphatidylinositol 3-kinase (PI3-K)/Akt signaling cascade revealed higher activities of PDK1 and Akt but not PI3-K in cav-1-stimulated cells compared to control cells. We subsequently found that cav-1 interacts with and inhibits serine/threonine protein phosphatases PP1 and PP2A through scaffolding domain binding site interactions. Deletion of the cav-1 scaffolding domain significantly reduces phosphorylated Akt and cell viability compared with wild-type cav-1. Analysis of potential substrates for PP1 and PP2A revealed that cav-1-mediated inhibition of PP1 and PP2A leads to increased PDK1, Akt, and ERK1/2 activities. We demonstrate that increased Akt activities are largely responsible for cav-1-mediated cell survival using dominant-negative Akt mutants and specific inhibitors to MEK1/MEK and show that cav-1 increases the half-life of phosphorylated PDK1 and Akt after inhibition of PI3-K by LY294002. We further demonstrate that cav-1-stimulated Akt activities lead to increased phosphorylation of multiple Akt substrates, including GSK3, FKHR, and MDM2. In addition, overexpression of cav-1 significantly increases translocation of phosphorylated androgen receptor to nucleus. Our studies therefore reveal a novel mechanism of Akt activation in prostate cancer and potentially other malignancies.
Mol Cell Biol 2003 Dec
PMID:Caveolin-1 maintains activated Akt in prostate cancer cells through scaffolding domain binding site interactions with and inhibition of serine/threonine protein phosphatases PP1 and PP2A. 1464 48

Identification of the key regulatory molecules in metastasis is crucial for understanding tumor dissemination and for the development of novel interventions. The recent identification of ezrin as a necessary component in the metastasis of osteosarcoma and rhabdomyosarcoma is, therefore, an important advance. Ezrin has been implicated in many roles, for example, as a conduit for signals between metastasis-associated cell-surface molecules and signal transduction components. This suggests that ezrin and, potentially, other members of the ERM (ezrin-radixin-moesin) family have key roles in the coordination of signals and cellular complexes that are required for the successful metastasis of these and other malignancies.
Trends Mol Med 2004 May
PMID:Ezrin, a key component in tumor metastasis. 1517 87

Skeletal muscle size depends upon a dynamic balance between anabolic (or hypertrophic) and catabolic (or atrophic) processes. Previously, no link between the molecular mediators of atrophy and hypertrophy had been reported. We demonstrate a hierarchy between the signals which mediate hypertrophy and those which mediate atrophy: the IGF-1/PI3K/Akt pathway, which has been shown to induce hypertrophy, prevents induction of requisite atrophy mediators, namely the muscle-specific ubiquitin ligases MAFbx and MuRF1. Moreover, the mechanism for this inhibition involves Akt-mediated inhibition of the FoxO family of transcription factors; a mutant form of FOXO1, which prevents Akt phosphorylation, thereby prevents Akt-mediated inhibition of MuRF1 and MAFbx upregulation. Our study thus defines a previously uncharacterized function for Akt, which has important therapeutic relevance: Akt is not only capable of activating prosynthetic pathways, as previously demonstrated, but is simultaneously and dominantly able to suppress catabolic pathways, allowing it to prevent glucocorticoid and denervation-induced muscle atrophy.
Mol Cell 2004 May 07
PMID:The IGF-1/PI3K/Akt pathway prevents expression of muscle atrophy-induced ubiquitin ligases by inhibiting FOXO transcription factors. 1512 42

The nuclear receptors CAR and PXR activate hepatic genes in response to therapeutic drugs and xenobiotics, leading to the induction of drug-metabolizing enzymes, such as cytochrome P450. Insulin inhibits the ability of FOXO1 to express genes encoding gluconeogenic enzymes. Induction by drugs is known to be decreased by insulin, whereas gluconeogenic activity is often repressed by treatment with certain drugs, such as phenobarbital (PB). Performing cell-based transfection assays with drug-responsive and insulin-responsive enhancers, glutathione S-transferase pull down, RNA interference (RNAi), and mouse primary hepatocytes, we examined the molecular mechanism by which nuclear receptors and FOXO1 could coordinately regulate both enzyme pathways. FOXO1 was found to be a coactivator to CAR- and PXR-mediated transcription. In contrast, CAR and PXR, acting as corepressors, downregulated FOXO1-mediated transcription in the presence of their activators, such as 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) and pregnenolone 16alpha-carbonitrile, respectively. A constitutively active mutant of the insulin-responsive protein kinase Akt, but not the kinase-negative mutant, effectively blocked FOXO1 activity in cell-based assays. Thus, insulin could repress the receptors by activating the Akt-FOXO1 signal, whereas drugs could interfere with FOXO1-mediated transcription by activating CAR and/or PXR. Treatment with TCPOBOP or PB decreased the levels of phosphoenolpyruvate carboxykinase 1 mRNA in mice but not in Car(-/-) mice. We conclude that FOXO1 and the nuclear receptors reciprocally coregulate their target genes, modulating both drug metabolism and gluconeogenesis.
Mol Cell Biol 2004 Sep
PMID:Nuclear receptors CAR and PXR cross talk with FOXO1 to regulate genes that encode drug-metabolizing and gluconeogenic enzymes. 1534 55

The chemotherapeutic activity of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU or carmustine) may be improved by the addition of O6-benzylguanine (O6-BG). The reaction of O6-BG with O6-alkylguanine-DNA alkyltransferase (AGT) prevents the repair of O6-chloroethyl lesions caused by BCNU. In clinics, the combination of O6-BG and BCNU is now being tested for the treatment of brain tumors. However, the effectiveness of this drug regimen may be limited by drug resistance acquired during treatment. To understand the possible mechanisms of resistance of brain tumor cells to the O6-BG/BCNU combination, we generated medulloblastoma cell lines (D283 MED, D341 MED, and Daoy) resistant to the combination of O6-BG and BCNU [O6-BG/BCNU resistant (OBR)]. DNA sequencing showed that all of the parent cell lines express wild-type AGTs, whereas every OBR cell line exhibited mutations that potentially affected the binding of O6-BG to the protein as evidenced previously by in vitro mutagenesis and structural studies of AGT. The D283 MED (OBR), Daoy (OBR), and D341 MED (OBR) cell lines expressed G156C, Y114F, and K165T AGT mutations, respectively. We reported previously that rhabdomyosarcoma TE-671 (OBR) also expresses a G156C mutation. These data suggest that the clonal selection of AGT mutants during treatment with O6-BG plus an alkylator may produce resistance to this intervention in clinical settings.
Mol Cancer Ther 2004 Sep
PMID:Brain tumor cell lines resistant to O6-benzylguanine/1,3-bis(2-chloroethyl)-1-nitrosourea chemotherapy have O6-alkylguanine-DNA alkyltransferase mutations. 1536 7

Endometriosis is a polygenic gynaecological condition affecting 5-15% of women of childbearing age. Major symptoms of the disease are pelvic pain and infertility. No clear link has been established between symptoms and the stage of the disease. Although some aspects have begun to be clarified, clinical understanding of endometriosis remains partial at the molecular level. In this perspective, we targeted isolation of differentially expressed genes in the eutopic endometrial tissue. Our assumption was that the endometrial cells of patients presented an unusual gene expression profile, allowing their implantation and survival in an ectopic site, leading to endometriotic lesions. Here, we report that mRNA steady-state levels of two key transcription factors are modulated in endometriosis. FOXO1 (also known as FKHR) levels were 1.6-fold lower in endometriosis compared to the control group at the onset of the secretory phase (day 15-21), while c-jun mRNA was present at higher amounts in endometriosis (1.5-fold) at the proliferative phase of the menstrual cycle. These results were derived from a large sample composed of 157 control subjects and 209 patients with endometriosis. Gene profiling was conducted by real-time quantitative PCR, and data were quality controlled before statistical analysis. Whether protein levels are affected as well remains to be investigated.
Mol Hum Reprod 2004 Dec
PMID:FOXO1 and c-jun transcription factors mRNA are modulated in endometriosis. 1550 4

Knowledge on molecular systems involved in myogenic precursor cell (mpc) fusion into myotubes is fragmentary. Previous studies have implicated the a disintegrin and metalloproteinase (ADAM) family in most mammalian cell fusion processes. ADAM12 is likely involved in fusion of murine mpc and human rhabdomyosarcoma cells, but it requires yet unknown molecular partners to launch myogenic cell fusion. ADAM12 was shown able to mediate cell-to-cell attachment through binding alpha9beta1 integrin. We report that normal human mpc express both ADAM12 and alpha9beta1 integrin during their differentiation. Expression of alpha9 parallels that of ADAM12 and culminates at time of fusion. alpha9 and ADAM12 coimmunoprecipitate and participate to mpc adhesion. Inhibition of ADAM12/alpha9beta1 integrin interplay, by either ADAM12 antisense oligonucleotides or blocking antibody to alpha9beta1, inhibited overall mpc fusion by 47-48%, with combination of both strategies increasing inhibition up to 62%. By contrast with blockade of vascular cell adhesion molecule-1/alpha4beta1, which also reduced fusion, exposure to ADAM12 antisense oligonucleotides or anti-alpha9beta1 antibody did not induce detachment of mpc from extracellular matrix, suggesting specific involvement of ADAM12-alpha9beta1 interaction in the fusion process. Evaluation of the fusion rate with regard to the size of myotubes showed that both ADAM12 antisense oligonucleotides and alpha9beta1 blockade inhibited more importantly formation of large (> or =5 nuclei) myotubes than that of small (2-4 nuclei) myotubes. We conclude that both ADAM12 and alpha9beta1 integrin are expressed during postnatal human myogenic differentiation and that their interaction is mainly operative in nascent myotube growth.
Mol Biol Cell 2005 Feb
PMID:ADAM12 and alpha9beta1 integrin are instrumental in human myogenic cell differentiation. 1557 85


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