Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P42345 (mTOR)
 26,049 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The increased levels of c-Myc protein observed previously in an ovarian carcinoma cell line stably transfected to express HER2 has suggested a role for the HER2 pathway in c-Myc expression. Analysis of HER2-transfected cells stimulated with heregulin beta1 (HRG) revealed increased c-Myc protein levels but not a corresponding increase in c-Myc mRNA expression or any change in c-Myc protein half-life. Transfection of HER2-overexpressing cells with a construct containing the 5' untranslated region (5'UTR) of c-Myc mRNA originated from the P2 promoter and placed upstream of the Renilla luciferase gene, enhanced reporter expression upon stimulation with HRG. The HRG-mediated increase in reporter activity correlated with the HRG-mediated induction observed for c-Myc protein, identifying the P2-derived leader (P2L) of c-Myc mRNA as the cis-element involved in c-Myc translational induction. Both the increase in c-Myc protein levels and P2L-enhanced translational activity were inhibited by the PI3K inhibitor wortmannin. Together, these results demonstrate that HRG stimulation of HER2 overexpressing cells leads to enhanced c-Myc protein synthesis through activation of the PI3K/Akt/mTOR pathway and that the P2L of c-Myc mRNA is the element responsible for induction of c-Myc translation.
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PMID:HER2 signaling enhances 5'UTR-mediated translation of c-Myc mRNA. 1513 60

Although significant improvements in standard therapy for ovarian carcinoma have been made over the past decade, current treatment is limited by the development of resistance to cytotoxic chemotherapy, and most women ultimately die of the disease. New knowledge of the biology of ovarian cancer has led to the identification of potential molecular targets that are differentially expressed in normal cells versus cancer cells, and advances in pharmacology have led to the development of novel agents that work differently from traditional cytotoxic chemotherapy by exploiting these targets. Many of these agents are being evaluated in clinical trials. This article discusses molecular targets that are important in ovarian carcinoma, including angiogenesis, tyrosine kinases, mitogen-activated protein kinases, and phosphatidylinositol-like kinases such as mammalian target of rapamycin, and the proteosome. This article reviews novel non-cytotoxic agents that target these pathways and are currently being evaluated in ovarian carcinoma treatment.
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PMID:Novel non-cytotoxic therapy in ovarian cancer: current status and future prospects. 1702 Jun 72

Mullerian Inhibiting Substance (MIS), a biological modifier that causes regression of Mullerian ducts in male embryos, is effective as a single agent in vitro and in vivo against human and mouse ovarian cancer cell lines expressing MIS type II receptor; however, little is known about how recombinant human MIS (rhMIS), now being scaled for preclinical trials, could be used in combination with cytotoxic or targeted chemotherapeutic agents. Mouse serous and endometrioid ovarian carcinoma cell lines were tested in vitro against rhMIS alone and with doxorubicin, paclitaxel, or cisplatin as agents in clinical use. Because MIS releases FK506 binding protein (FKBP12), which activates the mammalian target of rapamycin (mTOR) downstream of Akt, rhMIS and rapamycin combinations were tested. MIS increases p16 protein levels, and 5'-Aza-2'-deoxycytidine (AzadC) induces p16 mRNA; therefore, they were used in combination in vitro and in vivo with a human ovarian cancer cell line. A paclitaxel-resistant human ovarian cancer cell line and its parental line both respond to rhMIS in vitro. Additivity, synergy, or competition was observed with MIS and rapamycin, AzadC, doxorubicin, cisplatin, and paclitaxel, suggesting that MIS in combination with selective targeted therapies might achieve greater activity against ovarian cancer than the use of each individual agent alone. These assays and statistical analyses could be useful in selecting rhMIS and chemotherapeutic agent combinations that enhance clinical efficacy and reduce toxicity.
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PMID:Mullerian Inhibiting Substance enhances subclinical doses of chemotherapeutic agents to inhibit human and mouse ovarian cancer. 1708 39

Microglia of the central nervous system serve a variety of functions that may ultimately lead to the development or detriment of neighboring neuronal and vascular cells. These scavengers of the nervous system have been associated with a variety of neurodegenerative disorders, but the toxic potential of microglia is equally balanced by the protective nature of these cells to exclude foreign microorganisms and promote new tissue proliferation and reorganization. To this extent, our work outlines a series of endogenous microglial cellular pathways that can constitute protection for microglia against during oxygen-glucose deprivation (OGD). We demonstrate in both primary microglia and the microglial cell line EOC 2 that endogenous microglial protection against OGD relies upon the activation and expression of the phosphatidylinositol 3-kinase pathways of mammalian target of rapamycin (mTOR) and protein kinase B (Akt1), since pharmacological inhibition of mTOR or Akt1 as well as the gene silencing of Akt1 protein expression leads to significantly increased microglial apoptotic cell injury, DNA fragmentation, and membrane phosphatidylserine exposure. The mTOR pathway may offer endogenous protection through mechanisms that do not entirely rely upon inhibition of glycogen synthase kinase-3beta (GSK-3beta) activity while Akt1 appears to converge upon the necessary blockade of GSK-3beta. Closely aligned to these endogenous protective mechanisms is the subcellular presence and nuclear translocation of nuclear factor-kappaB p65 (NF-kappaB p65), since microglial cell injury is significantly increased during the gene silencing of NF-kappaB p65. Elucidating the underlying pathways that can afford endogenous protection and maintain functional integrity of microglia should offer new prospects for the treatment of a broad range of nervous system disorders.
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PMID:The pro-survival pathways of mTOR and protein kinase B target glycogen synthase kinase-3beta and nuclear factor-kappaB to foster endogenous microglial cell protection. 1720

The mammalian target of rapamycin (mTOR) is thought to play a critical role in regulating cell growth, cell cycle progression, and tumorigenesis. Because the AKT-mTOR pathway is frequently hyperactivated in ovarian cancer, we hypothesized that the mTOR inhibitor RAD001 (Everolimus) would inhibit ovarian tumorigenesis in transgenic mice that spontaneously develop ovarian carcinomas. We used TgMISIIR-TAg transgenic mice, which develop bilateral ovarian serous adenocarcinomas accompanied by ascites and peritoneal dissemination. Fifty-eight female TgMISIIR-TAg mice were treated with 5 mg/kg RAD001 or placebo twice weekly from 5 to 20 weeks of age. To monitor tumor development, mice were examined biweekly using magnetic resonance microimaging. In vivo effects of RAD001 on Akt-mTOR signaling, tumor cell proliferation, and blood vessel area were analyzed by immunohistochemistry and Western blot analysis. RAD001 treatment markedly delayed tumor development. Tumor burden was reduced by approximately 84%. In addition, ascites formation, together with peritoneal dissemination, was detected in only 21% of RAD001-treated mice compared with 74% in placebo-treated animals. Approximately 30% of RAD001-treated mice developed early ovarian carcinoma confined within the ovary, whereas all placebo-treated mice developed advanced ovarian carcinoma. Treatment with RAD001 diminished the expression of vascular endothelial growth factor in tumor-derived cell lines and inhibited angiogenesis in vivo. RAD001 also attenuated the expression of matrix metalloproteinase-2 and inhibited the invasiveness of tumor-derived cells. Taken together, these preclinical findings suggest that mTOR inhibition, alone or in combination with other molecularly targeted drugs, could represent a promising chemopreventive strategy in women at high familial risk of ovarian cancer.
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PMID:RAD001 (Everolimus) delays tumor onset and progression in a transgenic mouse model of ovarian cancer. 1736 57

Ovarian cancer is the leading cause of death from gynecologic cancer. Often, the disease has spread beyond the ovary to involve the peritoneal cavity and causes ascites. Whereas mammalian target of rapamycin (mTOR) functions to regulate protein translation, cell cycle progression, and metastasis, vascular endothelial growth factor promotes tumor angiogenesis, ascites formation, and metastasis in ovarian cancer. In this study, an i.p. model of human ovarian cancer was used to determine the antitumor activity of rapamycin, bevacizumab, and rapamycin plus bevacizumab (BEV/RAPA). We report that administration of rapamycin, bevacizumab, and BEV/RAPA in mice bearing peritoneal OV-90 ovarian carcinoma resulted in 74.6%, 82.4%, and 93.3% reduction in i.p. tumor burden, respectively. BEV/RAPA-induced reduction in microvessel density and inhibition of cell proliferation were associated with significant reduction in hypoxia-inducible factor-1alpha and cyclin D1 and inactivation of downstream targets of mTOR, p70S6 kinase, S6R, and 4E-binding protein 1. BEV/RAPA treatment was not only able to prolong life of i.p. mice but also more effective than rapamycin and bevacizumab to prevent the development of peritoneal carcinomatosis in adjuvant setting and reverse ascites accumulation in heavy peritoneal disease. Our data indicate that simultaneous inhibition of the vascular endothelial growth factor receptor and mTOR pathways with BEV/RAPA or their analogues may represent a novel approach for prevention of metastasis, recurrence, and treatment of ovarian cancer.
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PMID:Bevacizumab and rapamycin inhibit tumor growth in peritoneal model of human ovarian cancer. 1802 80

Vascular endothelial growth factor (VEGF)-A inhibitors exhibit unseen high responses and toxicity in recurrent epithelial ovarian cancer suggesting an important role for the VEGF/VEGFR pathway. We studied the correlation of VEGF signalling and AKT/mTOR signalling. Using a tissue microarray of clinical samples (N=86), tumour cell immunohistochemical staining of AKT/mTOR downstream targets, pS6 and p4E-BP1, together with tumour cell staining of VEGF-A and pVEGFR2 were semi-quantified. A correlation was found between the marker for VEGFR2 activation (pVEGFR2) and a downstream target of AKT/mTOR signalling (pS6) (R=0.29; P=0.002). Additional gene expression analysis in an independent cDNA microarray dataset (N=24) showed a negative correlation (R=-0.73, P<0.0001) between the RPS6 and the VEGFR2 gene, which is consistent as the gene expression and phosphorylation of S6 is inversely regulated. An activated tumour cell VEGFR2/AKT/mTOR pathway was associated with increased incidence of ascites (chi(2), P=0.002) and reduced overall survival of cisplatin-taxane-based patients with serous histology (N=32, log-rank test, P=0.04). These data propose that VEGF-A signalling acts on tumour cells as a stimulator of the AKT/mTOR pathway. Although VEGF-A inhibitors are classified as anti-angiogenic drugs, these data suggest that the working mechanism has an important additional modality of targeting the tumour cells directly.
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PMID:The VEGF pathway and the AKT/mTOR/p70S6K1 signalling pathway in human epithelial ovarian cancer. 1924 Jul 22

The epidermal growth factor receptor (EGFR) is dysregulated in various tumour types such as glioblastoma multiforme (GBM), breast cancer, ovarian carcinoma, non-small cell lung cancer and other cancers. As the intracellular tyrosine kinase of the EGFR activates signalling cascades leading to cell proliferation, angiogenesis and inhibition of apoptosis, the EGFR represents an attractive target in cancer therapy. In GBM which is the most common primary central nervous system tumour in adults, the EGFR is overexpressed in about 40 to 50% of cases, and almost half of these co-express the mutant receptor subtype EGFRvIII. This EGFR variant is constitutively activated, and thereby may contribute to the aggressive and refractory course of GBM which is associated with a median survival of only 40 to 60 weeks from diagnosis. Various trials are ongoing focusing on EGFR and EGFRvIII as new therapeutic targets in GBM. Anti-EGFR monoclonal antibodies (MAbs), e.g. cetuximab, and tyrosine kinase inhibitors (TKIs), e.g. erlotinib and gefitinib, are the most advanced in clinical development. Several trials are investigating MAbs or TKIs in combination with other agents such as inhibitors of the mammalian target of rapamycin. Other still preliminary approaches targeting the EGFR are small interfering RNA, antisense RNA and ribozymes, which lead to degradation of EGFR mRNA. Further studies are needed to define their clinical potential, to identify biological predictors of response and thus to characterize subgroups of patients who will benefit from treatment with these new agents.
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PMID:The epidermal growth factor receptor as a therapeutic target in glioblastoma multiforme and other malignant neoplasms. 1960 50

The transcription factor Forkhead Box P3 (Foxp3) has been shown to play important roles in the occurring of regulatory T cells (Tregs). Limited evidence indicated that it was also expressed in tissues other than thymus and spleen, while, very recently, it was identified as a suppressor gene in breast cancer. However, the precise role and molecular mechanism of the action of Foxp3 in ovarian cancer remained unclear. To elucidate the function of Foxp3, we examined the expression of Foxp3 in ovarian cancerous cells and the consequences of up-regulation of Foxp3 in epithelial ovarian cancer cell lines, respectively. By multiple cellular and molecular approaches such as gene transfection, CCK-8 assay, flow cytometry, RT-PCR, in-cell western, wound healing assay, and invasion assay, we found that Foxp3 was weakly/no expressed in ovarian cancerous cells. Up-regulation of Foxp3 inhibited cell proliferation, decreased cell migration, and reduced cell invasion. Compared with control, Foxp3 up-regulated cells showed decreased expression of Ki-67 and cyclin-dependent kinases (CDKs). Moreover, up-regulation of Foxp3 reduced the expression of matrix metalloproteinase-2 (MMP-2) and urokinase-type plasminogen activator (uPA), resulting in the inhibition of cell migration and invasion. In addition, Foxp3 up-regulation inhibited the activation of mammalian target of rapamycin (mTOR) and NF-kappaB signaling. These findings suggested that up-regulation of Foxp3 could be a novel approach for inhibiting ovarian cancer progression.
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PMID:Up-regulation of Foxp3 inhibits cell proliferation, migration and invasion in epithelial ovarian cancer. 1962 30

The AKT/mTOR signaling pathway is frequently overexpressed in human epithelial ovarian cancer and an attractive target for therapy. In vivo mouse models were confirmative for in vitro findings, where the administration of mTOR inhibitors in ovarian cancer xenografts showed antitumoral as well as antiangiogenic effects. Phase I - II trials are now ongoing with mTOR inhibitors in ovarian cancer patients, some in combination with conventional cytotoxic agents. If further development of mTOR inhibition in ovarian cancer is pursued, studying combinations of mTOR inhibitors with other new targeted therapies would be of interest. mTOR inhibitors in the adjuvant setting could have potential, since, for the moment, there is no standard maintenance therapy in ovarian cancer. A crucial challenge will be to identify strong predictive biomarkers. This review highlights the rationale for the use of mTOR inhibitors in ovarian cancer and summarizes the available preclinical findings.
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PMID:The rationale for mTOR inhibition in epithelial ovarian cancer. 1988 68


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