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

Mutations in the human Tsc1 and Tsc2 genes predispose to tuberous sclerosis complex (TSC), a disorder characterized by the wide spread of benign tumors. Tsc1 and Tsc2 proteins form a complex and serve as a GTPase-activating protein (GAP) for Rheb, a GTPase regulating a downstream kinase, mTOR. The genome of Schizosaccharomyces pombe contains tsc1(+) and tsc2(+), homologs of human Tsc1 and Tsc2, respectively. In this study we analyzed the gene expression profile on a genomewide scale and found that deletion of either tsc1(+) or tsc2(+) affects gene induction upon nitrogen starvation. Three hours after nitrogen depletion genes encoding permeases and genes required for meiosis are less induced. Under the same condition, retrotransposons, G1-cyclin (pas1(+)), and inv1(+) are more induced. We also demonstrate that a mutation (cpp1-1) in a gene encoding a beta-subunit of a farnesyltransferase can suppress most of the phenotypes associated with deletion of tsc1(+) or tsc2(+). When a mutant of rhb1(+) (homolog of human Rheb), which bypasses the requirement of protein farnesylation, was expressed, the cpp1-1 mutation could no longer suppress, indicating that deficient farnesylation of Rhb1 contributes to the suppression. On the basis of these results, we discuss TSC pathology and possible improvement in chemotherapy for TSC.
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PMID:A defect in protein farnesylation suppresses a loss of Schizosaccharomyces pombe tsc2+, a homolog of the human gene predisposing to tuberous sclerosis complex. 1662 1

CD28-deficient T cells arrest at the G1-S transition of the cell cycle. Here we show that this is controlled by the kinase aurora B, which exists in a complex with survivin and mammalian target of rapamycin (mTOR). Expression of aurora B in Cd28-/- T cells augmented phosphorylation of mTOR substrates, expression of cyclin A, hyperphosphorylation of retinoblastoma protein and activation of cyclin-dependent kinases 1 and 2 and promoted cell cycle progression. Interleukin 2 enhanced aurora B activity, and inactive aurora B prevented interleukin 2-induced proliferation. Moreover, expression of aurora B restored Cd28-/- T cell proliferation and promoted inflammation in vivo. These data identify aurora B, along with survivin and mTOR, as a regulator of the G1-S checkpoint in T cells.
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PMID:The kinases aurora B and mTOR regulate the G1-S cell cycle progression of T lymphocytes. 1712 76

Mantle cell lymphoma (MCL) is an aggressive form of B-cell non-Hodgkin's lymphoma, with a mean survival of only 3-5 years and suboptimal therapeutic options. MCL is characterized by a balanced translocation t(11;14)(q13;q32), resulting in overexpression of cyclin D1, a G(1) cyclin regulated by the PI3K/Akt/mammalian target of rapamycin (mTOR) signaling pathway. As improved therapy for MCL is required and the mTOR pathway may be involved in its pathophysiology, the antiproliferative effects of RAD001 (everolimus), an mTOR inhibitor, against three MCL cell lines were investigated. As a single agent, RAD001 inhibited proliferation in MCL cell lines (Jeko1, SP49 and NCEB1) approximately 40-65% compared to diluent control cells. This was associated with G(1) cell-cycle arrest and reduced phosphorylation of the mTOR downstream target, 4E-BP1. Furthermore, combination drug studies revealed predominantly synergistic cytotoxicity with RAD001 and several secondary agents, including doxorubicin, vincristine or rituximab (components of the standard MCL regimen), as well as paclitaxel, vorinostat and bortezomib. These data indicate that single agent RAD001 is effective in inhibiting growth of MCL cells in vitro and combination studies with secondary agents further demonstrate synergistic cytotoxicity. Thus, these findings support future clinical studies of RAD001 in the treatment of MCL.
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PMID:Antiproliferative activity of RAD001 (everolimus) as a single agent and combined with other agents in mantle cell lymphoma. 1713 16

Somatic mutations in the tuberous sclerosis complex-2 (TSC2) gene are associated with pulmonary lymphangioleiomyomatosis (LAM), a disorder characterized by benign lesions of smooth muscle and/or smooth muscle-like cells in the lung. However, the cellular mechanisms underlying LAM disease are largely unknown. Given that the TSC2 gene product tuberin is involved in the regulation of cell growth and proliferation, the present study was designed to investigate the potential roles of TSC2 in regulation of the cell cycle. We studied cell cycle profiles of pulmonary vascular smooth muscle cells (SMCs) derived from Eker rats (Tsc2(+/EK)), a genetic model carrying a germline insertional deletion in one copy of the Tsc2 gene, and the wild-type rats (Tsc2(+/+)), a noncarrier counterpart. We found that Tsc2(+/EK), but not Tsc2(+/+), SMCs displayed increases in cells with > or =4N DNA content (> or =4N cells) and in the bromodeoxyuridine (BrdU) incorporation of > or =4N cells. Centrosome number was also increased in Tsc2(+/EK) SMCs, but the mitotic index was comparable between Tsc2(+/+) and Tsc2(+/EK) SMCs. Furthermore, Tsc2(+/EK) SMCs showed elevated phosphorylation of p70S6K and increased expression of cell cycle regulatory proteins Cdk1, cyclin B, Cdk2, and cyclin E. Inhibition of the mammalian target of rapamycin (mTOR) pathway by rapamycin not only inhibited the phosphorylation of p70(S6K) and the expression of cell cycle regulatory proteins but also reduced accumulation of > or =4N cells and BrdU incorporation of >4N cells. Therefore, our results demonstrate that Tsc2(+/EK) SMCs are predisposed to undergo tetraploidization, involving activation of the mTOR pathway. These findings suggest an important role of Tsc2 in regulation of the cell cycle.
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PMID:Predisposition to tetraploidy in pulmonary vascular smooth muscle cells derived from the Eker rats. 1757 14

Hepatocellular carcinoma (HCC) is a frequent neoplasia which still misses a therapeutical gold standard. Recently, new acquisitions in cancerogenesis process evidenced the genetic and epigenetic alterations of genes involved in the different metabolic pathways of liver cancer suggesting that antibodies, small molecules, demethylating agents, etc. specifically acting against molecular target can be utilized alone or in combination in clinical practice. The main altered targets are: cell membrane receptors, in particular tyrosine kinase receptors, factors involved in cell signalling, specifically Wnt/beta-catenin, Ras/Raf/MEK/ERK and PI3K/Akt/mTOR pathways, proteins linked to cell cycle regulation pathway (i.e. p53, p16/INK4, cyclin/cdk complex) or in invasiveness (EMT, TGFbeta) and proteins involved in DNA metabolism. Genetic or epigenetic changes in these molecules have been used in preclinical settings and, some of them also in clinical trials of phase II and III. This scenario opens new avenues for the prevention and the treatment of HCC. In the present review the main metabolic pathways and molecular alterations have been described together with recent advances in molecular and gene therapy.
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PMID:Molecular pathways and related target therapies in liver carcinoma. 1804 79

Under steady-state conditions, major histocompatibility complex (MHC) I molecules are associated with self-peptides that are collectively referred to as the MHC class I peptide (MIP) repertoire. Very little is known about the genesis and molecular composition of the MIP repertoire. We developed a novel high-throughput mass spectrometry approach that yields an accurate definition of the nature and relative abundance of unlabeled peptides presented by MHC I molecules. We identified 189 and 196 MHC I-associated peptides from normal and neoplastic mouse thymocytes, respectively. By integrating our peptidomic data with global profiling of the transcriptome, we reached two conclusions. The MIP repertoire of primary mouse thymocytes is biased toward peptides derived from highly abundant transcripts and is enriched in peptides derived from cyclins/cyclin-dependent kinases and helicases. Furthermore, we found that approximately 25% of MHC I-associated peptides were differentially expressed on normal versus neoplastic thymocytes. Approximately half of those peptides are derived from molecules directly implicated in neoplastic transformation (e.g., components of the PI3K-AKT-mTOR pathway). In most cases, overexpression of MHC I peptides on cancer cells entailed posttranscriptional mechanisms. Our results show that high-throughput analysis and sequencing of MHC I-associated peptides yields unique insights into the genesis of the MIP repertoire in normal and neoplastic cells.
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PMID:The MHC class I peptide repertoire is molded by the transcriptome. 1829

The calcium/calmodulin-dependent kinase that phosphorylates and inactivates eukaryotic elongation factor 2 (eEF2 kinase; eEF2K) is subject to multisite phosphorylation, which regulates its activity. Phosphorylation at Ser359 inhibits eEF2K activity even at high calcium concentrations. To identify the kinase that phosphorylates Ser359 in eEF2K, we developed an extensive purification protocol. Tryptic mass fingerprint analysis identified it as cdc2 (cyclin-dependent kinase 1). cdc2 co-purifies with Ser359 kinase activity and cdc2-cyclin B complexes phosphorylate eEF2K at Ser359. We demonstrate that cdc2 contributes to controlling eEF2 phosphorylation in cells. cdc2 is activated early in mitosis. Kinase activity against Ser359 in eEF2K also peaks at this stage of the cell cycle and eEF2 phosphorylation is low in mitotic cells. Inactivation of eEF2K by cdc2 may serve to keep eEF2 active during mitosis (where calcium levels rise) and thereby permit protein synthesis to proceed in mitotic cells. Amino-acid starvation decreases cdc2's activity against eEF2K, whereas loss of TSC2 (a negative regulator of mammalian target of rapamycin complex 1(mTORC1)) increases it. These data closely match the control of Ser359 phosphorylation and indicate that cdc2 may be regulated by mTORC1.
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PMID:cdc2-cyclin B regulates eEF2 kinase activity in a cell cycle- and amino acid-dependent manner. 1833 51

The mammalian target of rapamycin (mTOR) pathway plays a central role in regulating protein synthesis, ribosomal protein translation, and cap-dependent translation. Deregulations in mTOR signaling are frequently associated with tumorigenesis, angiogenesis, tumor growth and metastasis. This review highlights the role of the mTOR in anticancer drug resistance. We discuss the network of signaling pathways in which the mTOR kinase is involved, including the structure and activation of the mTOR complex and the pathways upstream and downstream of mTOR as well as other molecular interactions of mTOR. Major upstream signaling components in control of mTOR activity are PI3K/PTEN/AKT and Ras/Raf/MEK/ERK pathways. We discuss the central role of mTOR in mediating the translation of mRNAs of proteins related to cell cycle progression, those involved in cell survival such as c-myc, hypoxia inducible factor 1* (HIF-1*) and vascular endothelial growth factor (VEGF), cyclin A, cyclin dependent kinases (cdk1/2), cdk inhibitors (p21(Cip1) and p27(Kip1)), retinoblastoma (Rb) protein, and RNA polymerases I and III. We then discuss the potential therapeutic opportunities for using mTOR inhibitors rapamycin, CCI-779, RAD001, and AP-23573 in cancer therapy as single agents or in combinations to reverse drug resistance.
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PMID:Role of mTOR in anticancer drug resistance: perspectives for improved drug treatment. 1844 Aug 54

Chemoprevention represents a promising strategy to reducing the incidence of prostate cancer which afflicts more than 240,000 males annually in the U.S. 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO) and its C-28 methyl ester (CCDO-Me) and C-28 imidazole (CDDO-Im) derivatives are synthetic oleanane triterpenoids that exhibit several-fold more potent antiinflammatory activity than naturally occurring oleanolic acid, but have not been investigated for prevention of the prostate. In order to evaluate the anticancer activity of CDDOs for prostate cancer, we have investigated the effect of synthetic oleanane triterpenoids on molecular targets relevant to the chemoprevention and treatment of prostate cancer in vitro in TRAMPC-1 cells derived from the primary tumor in the prostate of a transgenic adenocarcinoma of the mouse prostate (TRAMP) mouse. Data demonstrate that CDDOs strongly inhibit the proliferation of TRAMPC-1 cells with a potency order of CDDO-Me>CDDO-Im>CDDO. Because CDDO-Me showed the most growth inhibitory activity it was further analyzed for the anticancer activity. CDDO-Me induced apoptosis in TRAMPC-1 cells as shown by the increased binding of annexin V-FITC and cleavage of procaspases 3, -8, and -9. It effectively inhibited the molecular targets such as p-Akt, NF-kappaB, and p-mTOR and downstream effectors of mTOR (p-S6K1, cyclin-D1, and cdk4). Further, CDDO-Me inhibited NF-kappaB-regulated antiapoptotic Bcl-2, Bcl-xL, and XIAP and proangiogenic VEGF. Taken together, these data demonstrate that CDDO-Me is potentially a potent chemopreventive agent that inhibits several molecular targets that are known to play critical roles in the development and progression of prostate cancer.
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PMID:CDDO-Me inhibits proliferation, induces apoptosis, down-regulates Akt, mTOR, NF-kappaB and NF-kappaB-regulated antiapoptotic and proangiogenic proteins in TRAMP prostate cancer cells. 1847 40

Although zinc is one of the most important trace elements in the body, the mechanisms underlying zinc-induced cell proliferation have yet to be unraveled. Thus, we investigated the effect of zinc chloride (ZnCl(2)) on mouse embryonic stem (ES) cell proliferation and related signaling pathways. ZnCl(2) (40 microM) significantly increased [(3)H]-thymidine incorporation after 12 h of treatment. At moderate concentrations (> or =4 microM), ZnCl(2) increased cell cycle regulatory protein levels, [(3)H]-thymidine incorporation, and total cell numbers, but higher doses of ZnCl(2) (> or =200 microM) blocked this proliferative effect. ZnCl(2) induced the phosphorylation of Akt, c-Jun N-terminal kinases/stress-activated protein kinases (JNK/SAPK), p44/42 MAPKs, and mammalian target of rapamycin (mTOR) in a time-dependent manner. Pretreatment of LY 294002 (a PI3K inhibitor, 10(-6) M), wortmannin (a PI3K inhibitor, 10(-7) M), or an Akt inhibitor (10(-5) M), which inhibited the activation of JNK/SAPK and p44/42 MAPKs, blocked the ZnCl(2)-induced expression of cyclins and cyclin-dependent kinases (CDKs). Furthermore, pretreatment with PD 98059 (a p44/42 inhibitor, 10(-5) M) or SP 600125 (a JNK inhibitor, 10(-6) M) inhibited ZnCl(2)-induced activation of mTOR, p70S6K, and 4E-BP1. In addition, rapamycin (an mTOR inhibitor, 10(-8) M) blocked the ZnCl(2)-induced increase in [(3)H]-thymidine incorporation and cell cycle regulatory protein expression. In conclusion, ZnCl(2) stimulated ES cell proliferation through the PI3K/Akt, p44/42 MAPKs, JNK/SAPK, and mTOR signal pathways.
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PMID:Zinc chloride stimulates DNA synthesis of mouse embryonic stem cells: involvement of PI3K/Akt, MAPKs, and mTOR. 1898 95


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