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)

Inhibition of the phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway is an appealing method for decreasing the immunoresistance and augmenting T cell-mediated immunotherapy. A major impediment to this strategy is the impact of conventional PI3K/mTOR pathway inhibitors on T cell function. In particular, rapamycin, is a well-known immunosuppressant that can decrease the activity of the PI3K/mTOR pathway in tumor cells, but also has a profound inhibitory effect on T cells. Here we show that Honokiol, a natural dietary product isolated from an extract of seed cones from Magnolia grandiflora, can decrease PI3K/mTOR pathway-mediated immunoresistance of glioma, breast and prostate cancer cell lines, without affecting critical proinflammatory T cell functions. Specifically, we show that at doses sufficient to down-regulate levels of phospho-S6 and the negative immune regulator B7-H1 in tumor cells, Honokiol does not significantly impair T cell proliferation or proinflammatory cytokine production. In contrast to classic inhibitors, including LY294002, wortmannin, AKT inhibitor III and rapamycin, Honokiol specifically decreases the PI3K/mTOR pathway activity in tumor cells, but not in freshly stimulated T cells. Collectively, our data define a unique application for Honokiol and provide the impetus to more fully elucidate the mechanism by which T cells are resistant to the effects of this particular inhibitor. Honokiol is clinically available for human testing and may serve to augment T cell-mediated cancer immunotherapy.
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PMID:Honokiol-mediated inhibition of PI3K/mTOR pathway: a potential strategy to overcome immunoresistance in glioma, breast, and prostate carcinoma without impacting T cell function. 2063 86

The recent introduction of drugs that inhibit angiogenesis or the mTOR has provided new options for the treatment of metastatic renal cell carcinoma, a disease which often has a poor prognosis. Chemotherapy and cytokine therapy are largely ineffective. The 5-year survival rate is under 10%. Everolimus, an immunosuppressive drug widely used for the prevention of allograft rejection and an mTOR inhibitor, is one of the latest drugs undergoing clinical trials in metastatic renal cell carcinoma. It has been tested in patients with progressive disease after therapy with tyrosine kinase receptor inhibitors (sunitinib, sorafenib or both), which interfere with signaling pathways, such as the VEGF pathway. Clinical efficacy results (progression-free survival) for everolimus are promising and the safety profile is good.
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PMID:Everolimus (RAD001): an mTOR inhibitor for the treatment of metastatic renal cell carcinoma. 1949 7

The pharmacological management of systemic lupus erythematosus (SLE) is challenging owing to its unpredictable clinical course, the variable organ system involvement and the lack of clear understanding of disease pathogenesis. The widely used corticosteroids and immunosuppressive drugs, which can control disease activity, have serious, potentially fatal, side effects. In the last decade, a better understanding of lupus pathogenesis has led to the development of biological agents that are directed at biomarkers. However, these biologicals also exert side effects due to infections resulting from completely eliminating immune cells (e.g., B cells) or cytokine signals (e.g., interferon-alpha) or affecting molecular targets outside the immune system (CD40L on platelets). New biomarker-driven clinical trials are ongoing to evaluate the safety and efficacy of B-cell depletion, blocking of interferon signaling, inhibition of the mTOR pathway, and restoration of glutathione deficiency in lupus T cells.
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PMID:Pharmacotherapy of systemic lupus erythematosus. 1950 15

Acute and chronic GVHD after allogeneic hematopoetic stem cell transplantation are still associated with significant morbidity and mortality. For prophylaxis of acute GVHD calcineurin inhibitors in combination with an antimetabolite (MTX or MMF) are administered, and these therapies are based on controlled studies. New prophylaxis strategies include mTOR-inhibitors in combination with tacrolimus but require confirmation by controlled trials. First-line treatment of acute GVHD consists mainly of steroids with doses ranging from 1 mg/kg/day prednisone to 3 mg/kg/day methylprednisolone. Second-line treatment of acute GVHD after failure of steroids is less well defined due to the lack of controlled studies. Treatment options are the use of cytotoxic antibodies (ATG, campath), cytokine blocking agents (etanercept, daclizumab), immunomodulating modalities (photopheresis), and antimetabolites (pentostatin, MMF). Recently, cellular approaches were developed, such as the adoptive transfer of mesenchymal stem cells. Nevertheless steroid-resistant acute GVHD is still a main challenge in alloHSCT and associated with high mortality. First-line treatment of chronic GVHD is also based on steroids with 1 mg/kg/day prednisolone or prednisone, which are often combined with calcineurin inhibitors. There is no consensus on second-line treatment of chronic GVHD and most therapies are solely based on phase II trials. Treatment options are the use of immunomodulating modalities (photopheresis, mTOR-inhibitors) and antimetabolites (MMF, MTX, pentostatin). Recent reports showed an efficacy of rituximab in selected patients. Other treatment options are low dose total nodal irradiation or the use of antibodies like ATG. Moreover, successful topical treatment of manifestations of chronic GVHD manifestations has been reported consisting of topical steroids like budesonide, topical calcineurin inhibitors, or PUVA.
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PMID:Pharmaceutical and cellular strategies in prophylaxis and treatment of graft-versus-host disease. 1951 37

Effector T cell differentiation requires the simultaneous integration of multiple, and sometimes opposing, cytokine signals. We demonstrated mTOR's role in dictating the outcome of T cell fate. mTOR-deficient T cells displayed normal activation and IL-2 production upon initial stimulation. However, such cells failed to differentiate into T helper 1 (Th1), Th2, or Th17 effector cells. The inability to differentiate was associated with decreased STAT transcription factor activation and failure to upregulate lineage-specific transcription factors. Under normally activating conditions, T cells lacking mTOR differentiated into Foxp3(+) regulatory T cells. This was associated with hyperactive Smad3 activation in the absence of exogenous TGF-beta. Surprisingly, T cells selectively deficient in TORC1 do not divert to a regulatory T cell pathway, implicating both TORC1 and TORC2 in preventing the generation of regulatory T cells. Overall, our studies suggest that mTOR kinase signaling regulates decisions between effector and regulatory T cell lineage commitment.
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PMID:The mTOR kinase differentially regulates effector and regulatory T cell lineage commitment. 1953 25

Renal cell carcinoma (RCC) is very resistant to both chemotherapy and radiotherapy. Localized disease can be cured by surgery but most patients are diagnosed when distant metastases are already present and about 30% of patients relapse after nephrectomy. Until 2 years ago, cytokine-based immunotherapy (interleukin-2 and interferon-alpha) was the only therapeutic option for advanced RCC patients. Fewer than 20% of patients benefit from this treatment, but some of these may experience very prolonged complete responses and progression-free intervals, suggesting a possibility of cure in a very few cases. Thanks to our expanding knowledge of the biology and pathogenesis of RCC, the treatment of this disease has recently undergone a major advance, through the development of potent angiogenesis inhibitors and targeted agents. Bevacizumab, an antibody directed against vascular endothelial growth factor (VEGF), has shown significant activity in combination with interferon-alpha (IFN-alpha). Sunitinib and sorafenib, multikinase inhibitors with proven antiangiogenic activity, have also been approved for the treatment of this tumor. Finally, temsirolimus and everolimus, which belong to the family of mammalian target of rapamycin (mTOR), have shown some activity in selected patients. The aim of this paper is to review clinical trials with these new agents, describing their activity and profiles of toxicity, and to evaluate potential future developmental strategies.
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PMID:A survey of therapy for advanced renal cell carcinoma. 1957

Shiga toxin 1 (Stx1) transiently increases the expression of proinflammatory cytokines by macrophage-like THP-1 cells in vitro. Increased cytokine production is partly due to activation of the translation initiation factor eIF4E through a mitogen-activated protein kinase (MAPK)- and Mnk1-dependent pathway. eIF4E availability for translation initiation is regulated by association with eIF4E binding proteins (4E-BP). In this study, we showed that Stx1 transiently induced 4E-BP hyperphosphorylation, which may release eIF4E for translation initiation. Phosphorylation of 4E-BP at priming sites T37 and T46 was not altered by Stx1 but was transiently increased at S65, concomitant with increased cytokine expression. Using kinase inhibitors, we showed that 4E-BP phosphorylation was dependent on phosphatidylinositol 3-kinase (PI3K), Akt, and mammalian target of rapamycin (mTOR) activation but did not require MAPKs. Stx1 treatment resulted in increased levels of cytosolic Ca(2+). PI3K and Akt activation led to the phosphorylation and inactivation of the positive cytokine regulator glycogen synthase kinase 3alpha/beta (GSK-3alpha/beta). PI3K, Akt, and mTOR inhibitors and small interfering RNA knockdown of Akt expression all increased, whereas a GSK-3alpha/beta inhibitor decreased, Stx1-induced soluble tumor necrosis factor alpha and interleukin-1beta production. Overall, these findings suggest that despite transient activation of 4E-BP, the PI3K/Akt/mTOR pathway negatively influences cytokine induction by inactivating the positive regulator GSK-3alpha/beta.
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PMID:Shiga toxin 1-induced proinflammatory cytokine production is regulated by the phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin signaling pathway. 1959 74

The molecular pathways that regulate thrombopoiesis are becoming increasingly understood. Upon binding to its receptor, the product of the c-Mpl proto-oncogene, thrombopoietin activates a number of secondary messengers that promote cell survival, proliferation and differentiation. Amongst the best studied are the signal transducers and activators of transcription, phosphoinositol-3-kinase, and the mitogen-activated protein kinases. Additional signals activated by these secondary mediators include mammalian target of rapamycin, beta-catenin, hypoxia-inducible factor 1alpha and the homeobox proteins HOXB4 and HOXA9, and a number that are reduced, including glycogen synthase kinase 3alpha and the FOXO3 family of forkhead proteins. More recently, a number of signaling pathways have been identified that turn the thrombopoietin signal off, a step necessary to avoid uncontrolled myeloproliferation, and include the phosphatases PTEN, SHP1 and SHIP1, the suppressors of cytokine signaling, and down-modulation of surface expression of c-Mpl. This review will focus on these pathways in normal and neoplastic hematopoiesis.
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PMID:Molecular mechanisms of thrombopoietin signaling. 1963 Aug 7

The past 5 years were marked by fundamental changes in the systemic therapy of metastatic renal cell carcinoma. Up to the end of the last decade cytokine-based chemotherapy was the only, even if only moderately effective systemic therapy for metastatic renal cell carcinoma. Currently there are five new approved drug releases of so-called targeted substances, which function on a molecular based therapeutic mechanism. Sunitinib (Sutent) and sorafenib (Nexavar) as multikinase inhibitors, everolimus (Afinitor) and temsirolimus (Torisel) as mTOR inhibitors, and bevacizumab as an antibody against VEGF in combination with interferon-alpha (IFN-alpha). The following article will give an overview of the currently available substances and critically discuss therapy plans and future trends.
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PMID:[Current state of systemic therapy of metastatic renal cell carcinoma]. 1966 18

Metastatic renal cell carcinoma (RCC) is notoriously chemoresistant; up until recently, immunotherapy (in particular interferon-alpha) has represented the treatment of choice. The understanding of the biology of RCC has resulted in the development of targeted therapies. In particular, multikinase inhibitors (sunitinib, sorafenib, axitinib, pazopanib), antivascular endothelial growth factor agents (bevacizumab), and mammalian target of rapamycin inhibitors (temsirolimus, everolimus) now have a role in the approach to different subsets of RCC. Sunitinib is indicated for the first-line therapy of metastatic RCC as a consequence of a positive phase III trial versus interferon-alpha; sorafenib is now registered for the second-line treatment of RCC, which was earlier treated with cytokine as a consequence of a positive phase III trial versus placebo. Bevacizumab is also indicated in the first-line treatment of metastatic RCC given in combination with interferon-alpha as a consequence of two positive phase III trials. Temsirolimus, unlike the other agents, has also shown activity in poor-prognosis patients, and is now the treatment of choice in previously untreated poor-prognosis RCC as a single agent. Everolimus can be considered as the best therapeutic option in patients with RCC pretreated with targeted agents as a consequence of a positive phase III study versus best supportive care. Markers for appropriate treatment selection, combined use of targeted agents, treatment of special histologies, and adjuvant and neoadjuvant setting represent important special issues to be dealt with in future studies.
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PMID:New treatment approaches in renal cell carcinoma. 1975 18


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