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 first liver transplantation (LT) was conducted in 1963. After a two-decade development phase with the improvement of surgical and anesthesia-resuscitation techniques, and a better control of allograft rejection, LT has become the benchmark treatment for the majority of end-stage liver diseases. Since the 1980s, indications of LT have gradually expanded and the current main indications in adults are hepatocellular carcinoma at an early stage (15 to 30% of indications), C cirrhosis (15 to 40% of indications) and alcoholic cirrhosis (20 to 25% of indications). Five thousand LTs are performed yearly in Europe, including 1000 LTs in France, with, over the 2000-2006 period, survival rates of 86, 75 and 68% at one, five and 10 years, respectively. Several advances have accompanied the increasing number of indications and these excellent results: (a) the development of more specific immunosuppressive drugs to prevent rejection, the incidence of which is currently less than 20%: tacrolimus, mycophenolic acid, anti-IL2 receptor antibodies, mTOR inhibitors, (b) a policy of active recruitment of organs together with surgical innovations (split liver, domino LT, living donor transplantation) contributing to the expansion of the pool of organs, (c) standardization of organ allocation policies, based on the sickest first policy. The applicability of LT, however, remains limited by the shortage of organs and the occurrence of long-term complications of immunosuppression. Due to the lack of effective alternative perspectives to LT for the treatment of end-stage liver diseases, the two major challenges for the liver transplant community should be the optimization of organ recruitment and the development of innovative immunosuppressive regimens able to overcome the side effects of current immunosuppressive drugs. The development of non heart beating donation and appropriate use of intrafamilial donation could partly compensate for the organ shortage in the midterm. The identification of molecular signatures in tolerant patients in whom immunosuppression could be stopped, and induction of tolerance, trough lymphocyte depletion or T lymphocyte costimulation blockade, are the most advanced research ways to reduce complications of immunosuppression.
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PMID:[Hepatic transplantation]. 1955 84

Tyrosine Kinase Inhibitors (TKI) have significantly changed the landscape of current cancer therapy. Understanding of mechanisms of aberrant TK signaling and strategies to inhibit TKs in cancer, further promote the development of novel agents.ABT-869, a novel ATP-competitive receptor tyrosine kinase inhibitor is a potent inhibitor of members of the vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) receptor families. ABT-869 showed potent antiproliferative and apoptotic properties in vitro and in animal cancer xenograft models using tumor cell lines that were "addicted" to signaling of kinases targeted by ABT-869. When given together with chemotherapy or mTOR inhibitors, ABT-869 showed at least additive therapeutic effects. The phase I trial for ABT-869 was recently completed and it demonstrated respectable efficacy in solid tumors including lung and hepatocellular carcinoma with manageable side effects. Tumor cavitation and reduction of contrast enhancement after ABT-869 treatment supported the antiangiogenic activity. The correlative laboratory studies conducted with the trial also highlight potential biomarkers for future patient selection and treatment outcome.Parallel to the clinical development, in vitro studies on ABT-869 resistance phenotype identified novel resistance mechanism that may be applicable to other TKIs. The future therapeutic roles of ABT-869 are currently been tested in phase II trials.
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PMID:ABT-869, a promising multi-targeted tyrosine kinase inhibitor: from bench to bedside. 1964 98

In the previous studies, (-)-epigallocatechin-3-gallate (EGCG) has been shown to have anticarcinogenic effects via modulation in protein expression of p53. Using p53 positive Hep G2 and p53 negative Hep 3B cells, we found that treatment of EGCG resulted in dose-dependent inhibition of cellular proliferation, which suggests that the interaction of EGCG with p53 may not fully explain its inhibitory effect on proliferation. Caloric restriction (CR) reduces the incidence and progression of spontaneous and induced tumors in laboratory rodents. EGCG has multiple beneficial activities similar to those associated with CR. One key enzyme thought to be activated during CR is AMP-activated kinase (AMPK), a sensor of cellular energy levels. Here, we showed that EGCG activated AMPK in both p53 positive and negative human hepatoma cells. The activation of AMPK suppressed downstream substrates, such as mammalian target of rapamycin (mTOR) and eukaryotic initiation factor 4E-binding protein-1 (4E-BP1) and a general decrease in mRNA translation. Moreover, EGCG activated AMPK decreases the activity and/or expression of lipogenic enzymes, such as fatty acid synthase (FASN) and acetyl-CoA carboxylase (ACC). Interestingly, the decision between apoptosis and growth arrest following AMPK activation is greatly influenced by p53 status. In p53 positive Hep G2 cells, EGCG blocked the progression of cell cycle at G1 phase by inducing p53 expression and further up-regulating p21 expression. However, EGCG inducted apoptosis in p53 negative Hep 3B cells. Based on these results, we have demonstrated that EGCG has a potential to be a chemoprevention and anti-lipogenesis agent for human hepatoma cells.
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PMID:EGCG inhibits protein synthesis, lipogenesis, and cell cycle progression through activation of AMPK in p53 positive and negative human hepatoma cells. 1966 44

5'AMP-activated protein kinase (AMPK) and the mammalian target of rapamycin (mTOR) are two serine/threonine protein kinases responsible for cellular energy homeostasis and translational control, respectively. Evidence suggests that these two kniases are potential targets for cancer chemotherapy against hepatocellular carcinoma (HCC). Antroquinonol that is isolated from Antrodia camphorate, a well-known Traditional Chinese Medicine for treatment of liver diseases, displayed effective anticancer activity against both HBV DNA-positive and -negative HCC cell lines. The rank order of potency against HCCs is HepG2>HepG2.2.15>Mahlavu>PLC/PRF/5>SK-Hep1>Hep3B. Antroquinonol completely abolished cell-cycle progression released from double-thymidine-block synchronization and caused a subsequent apoptosis. The data were supported by down-regulation and reduced nuclear translocation of G1-regulator proteins, including cyclin D1, cyclin E, Cdk4 and Cdk2. Further analysis showed that the mRNA expressions of the G1-regulator proteins were not modified by antroquinonol, indicating an inhibition of translational but not transcriptional levels. Antroquinonol induced the assembly of tuberous sclerosis complex (TSC)-1/TSC2, leading to the blockade of cellular protein synthesis through inhibition of protein phosphorylation including mTOR (Ser(2448)), p70(S6K) (Thr(421)/Ser(424) and Thr(389)) and 4E-BP1 (Thr(37)/Thr(46) and Thr(70)). Furthermore, the AMPK activity was elevated by antroquinonol. Compound C, a selective AMPK inhibitor, significantly reversed antroquinonol-mediated effects suggesting the crucial role of AMPK. Besides, the loss of mitochondrial membrane potential and depletion of mitochondrial content indicated the mitochondrial stress caused by antroquinonol. In summary, the data suggest that antroquinonol displays anticancer activity against HCCs through AMPK activation and inhibition of mTOR translational pathway, leading to G1 arrest of the cell-cycle and subsequent cell apoptosis.
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PMID:Antroquinonol displays anticancer potential against human hepatocellular carcinoma cells: a crucial role of AMPK and mTOR pathways. 1972 12

The mammalian target of rapamycin (mTOR) is an intracellular serine/threonine protein kinase positioned at a central point in a variety of cellular signaling cascades. The established involvement of mTOR activity in the cellular processes that contribute to the development and progression of cancer has identified mTOR as a major link in tumorigenesis. Consequently, inhibitors of mTOR, including temsirolimus, everolimus, and ridaforolimus (formerly deforolimus) have been developed and assessed for their safety and efficacy in patients with cancer. Temsirolimus is an intravenously administered agent approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMEA) for the treatment of advanced renal cell carcinoma (RCC). Everolimus is an oral agent that has recently obtained US FDA and EMEA approval for the treatment of advanced RCC after failure of treatment with sunitinib or sorafenib. Ridaforolimus is not yet approved for any indication. The use of mTOR inhibitors, either alone or in combination with other anticancer agents, has the potential to provide anticancer activity in numerous tumor types. Cancer types in which these agents are under evaluation include neuroendocrine tumors, breast cancer, leukemia, lymphoma, hepatocellular carcinoma, gastric cancer, pancreatic cancer, sarcoma, endometrial cancer, and non-small-cell lung cancer. The results of ongoing clinical trials with mTOR inhibitors, as single agents and in combination regimens, will better define their activity in cancer.
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PMID:Targeting tumorigenesis: development and use of mTOR inhibitors in cancer therapy. 1986 Sep 3

Though several naphthalimide derivatives have exhibited antitumor activity in clinical trials, some issues such as toxicity prompted further structural modifications on the naphthalimide backbone. A series of naphthalimides conjugated with polyamines were synthesized to harness the polyamine transporter (PAT) for drug delivery, which was beneficial for the tumor cell selectivity. Bioevaluation in human hepatoma HepG2 cells treated with alpha-difluoromethylornithine (DFMO) or spermidine (Spd), human hepatoma Bel-7402 and normal QSG-7701 hepatocyte confirmed the PAT recognition and cell selectivity. In addition, the novel naphthalimide polyamine conjugate kills cells via apoptosis, and the Akt/mTOR signal pathway was first identified as the upstream cellular target through the apoptotic mechanism research. The presence of DFMO or Spd only either elevated or attenuated the cell apoptosis, but did not change the signal pathway. Collectively, the proper polyamine recognition element (i.e., homospermidine) mediated effective drug delivery via the PAT, and helped the proper cytotoxic goods (i.e., diverse naphthalimides) exert antitumor properties.
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PMID:Conjugation of substituted naphthalimides to polyamines as cytotoxic agents targeting the Akt/mTOR signal pathway. 1986 1

Nutrient overload is associated with the development of obesity, insulin resistance, and type II diabetes. High plasma concentrations of amino acids have been found to correlate with insulin resistance. At the cellular level, excess amino acids impair insulin signaling, the mechanisms of which are not fully understood. Here, we report that STAT3 plays a key role in amino acid dampening of insulin signaling in hepatic cells. Excess amino acids inhibited insulin-stimulated Akt phosphorylation and glycogen synthesis in mouse primary hepatocytes as well as in human hepatocarcinoma HepG2 cells. STAT3 knockdown protected insulin sensitivity from inhibition by amino acids. Amino acids stimulated the phosphorylation of STAT3 at Ser(727), but not Tyr(705). Replacement of the endogenous STAT3 with wild-type, but not S727A, recombinant STAT3 restored the ability of amino acids to inhibit insulin signaling, suggesting that Ser(727) phosphorylation was critical for STAT3-mediated amino acid effect. Furthermore, overexpression of STAT3-S727D was sufficient to inhibit insulin signaling in the absence of excess amino acids. Our results also indicated that mammalian target of rapamycin was likely responsible for the phosphorylation of STAT3 at Ser(727) in response to excess amino acids. Finally, we found that STAT3 activity and the expression of its target gene socs3, known to be involved in insulin resistance, were both stimulated by excess amino acids and inhibited by rapamycin. In conclusion, our study reveals STAT3 as a novel mediator of nutrient signals and identifies a Ser(727) phosphorylation-dependent and Tyr(705) phosphorylation-independent STAT3 activation mechanism in the modulation of insulin signaling.
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PMID:Signal transducer and activator of transcription 3 (STAT3) mediates amino acid inhibition of insulin signaling through serine 727 phosphorylation. 1987 58

Patients with advanced hepatocellular carcinoma (HCC) have shown to benefit from tamoxifen treatment. The mechanisms of tamoxifen effects in HCC, however, are not yet clearly understood. The PI3K/Akt/mTOR signal pathway is involved in cell proliferation, tumorigenesis, and apoptosis. Over-expression of survivin has played an important role in leading to antiapoptosis. The current study investigated changes in mTOR pathway and survivin expression in hepatocarcinoma cell line HepG2 treated with tamoxifen. We detected apoptosis of hepatocarcinoma cells by flow cytometry assay. Survivin transcription level and p70S6k was demonstrated by PCR, dual-luciferase reporter assay and western blot analysis respectively. Our results are showed as follows: tamoxifen leads to apoptosis of the cells, and reduction in survivin expression, as well as a dramatic reduction in the activated form of p70S6 kinase. Twenty micromoles tamoxifen treatment significantly depresses transcription of survivin mRNA. Treating HepG2 cells with rapamycin, a specific mTOR inhibitor, significantly reduce survivin protein level but did not affect survivin transcription, which indicated that tamoxifen and rapamycin were synergistic in regards to down-regulation of survivin expression in hepatocellular carcinoma cells. Our results suggest that tamoxifen down-regulate survivin expression in HepG2 cells is mediated by transcriptional and posttranscriptional level via PI3K/Akt/mTOR pathway to induce apoptosis.
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PMID:Involvement of mTOR and survivin inhibition in tamoxifen-induced apoptosis in human hepatoblastoma cell line HepG2. 1993 98

Liver transplantation is considered the best treatment of hepatocellular carcinoma but its efficacy depends on the risk of tumour recurrence. The risk of recurrence depends on tumour characteristics but is also influenced by immunosuppressive regimens. Immunosuppressants of the mTOR inhibitors family share anti-tumour properties which are already taken into account in the treatment of renal carcinoma and advanced hepatocellular carcinoma. These features make interesting their use in liver transplantation for hepatocellular carcinoma, with the following goals: to reduce the risk of post-transplant tumour recurrence, to expand the indications of liver transplantation for hepatocellular carcinoma and eventually to slow down tumour growth during the waiting period. However, to date, the potential role of mTOR inhibitors after liver transplantation for hepatocellular carcinoma is only based on small encouraging proof of concept studies. Large randomized studies are therefore required to further define the specific indications of these compounds. The demonstration of a beneficial impact of mTOR inhibitors in the setting of liver transplantation for hepatocellular carcinoma would be a major therapeutical advance.
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PMID:[Liver transplantation for hepatocellular carcinoma and potential application of PSI]. 2000 32

The mammalian target of rapamycin (mTOR) is implicated in cell growth especially during cancer development and progression. Its action is dependent on well known oncogenic pathways that regulate tumor cell growth and cell cycle progression, in response to different stimuli. Sirolimus, temsirolimus and everolimus are specific inhibitors of mTOR that have originally been characterized by their antifungal and immunosuppressive properties, but also significantly inhibit cancer cells'proliferation, invasion, and metastasis, and promote apoptosis. In addition, mTOR inhibitors display potent antiangiogenic properties by the suppression of vascular endothelial growth factor signal transduction. The antitumoral effects of mTOR inhibitors, as a monotherapy or in combination with tyrosine kinase inhibitors or usual cytotoxic agents, have been extensively suggested in preclinical studies, including animal models. In a clinical setting, preliminary reports have demonstrated that mTOR inhibitors use is associated with an acceptable safety profile. Currently, mTOR inhibitors are tested in multiple trials and various cancer types, usually in intermittent schedules to avoid significant immunosuppression. Of particular interest is the use of mTOR inhibitors in the field of organ transplantation, including liver transplantation, in preventive or curative strategies, for the treatment of recurrent hepatocellular carcinoma and de novo post-transplantation malignancies.
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PMID:[Antitumoral effect of proliferation signal inhibitors]. 2000 33


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