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  1. Delayed mTOR Inhibition with Low Dose of Everolimus Reduces TGFβ Expression, Attenuates Proteinuria and Renal Damage in the Renal Mass Reduction Model

    PubMed Central

    Kurdián, Melania; Herrero-Fresneda, Inmaculada; Lloberas, Nuria; Gimenez-Bonafe, Pepita; Coria, Virginia; Grande, María T.; Boggia, José; Malacrida, Leonel; Torras, Joan; Arévalo, Miguel A.; González-Martínez, Francisco; López-Novoa, José M.; Grinyó, Josep; Noboa, Oscar

    2012-01-01

    Background The immunosuppressive mammalian target of rapamycin (mTOR) inhibitors are widely used in solid organ transplantation, but their effect on kidney disease progression is controversial. mTOR has emerged as one of the main pathways regulating cell growth, proliferation, differentiation, migration, and survival. The aim of this study was to analyze the effects of delayed inhibition of mTOR pathway with low dose of everolimus on progression of renal disease and TGFβ expression in the 5/6 nephrectomy model in Wistar rats. Methods This study evaluated the effects of everolimus (0.3 mg/k/day) introduced 15 days after surgical procedure on renal function, proteinuria, renal histology and mechanisms of fibrosis and proliferation. Results Everolimus treated group (EveG) showed significantly less proteinuria and albuminuria, less glomerular and tubulointerstitial damage and fibrosis, fibroblast activation cell proliferation, when compared with control group (CG), even though the EveG remained with high blood pressure. Treatment with everolimus also diminished glomerular hypertrophy. Everolimus effectively inhibited the increase of mTOR developed in 5/6 nephrectomy animals, without changes in AKT mRNA or protein abundance, but with an increase in the pAKT/AKT ratio. Associated with this inhibition, everolimus blunted the increased expression of TGFβ observed in the remnant kidney model. Conclusion Delayed mTOR inhibition with low dose of everolimus significantly prevented progressive renal damage and protected the remnant kidney. mTOR and TGFβ mRNA reduction can partially explain this anti fibrotic effect. mTOR can be a new target to attenuate the progression of chronic kidney disease even in those nephropathies of non-immunologic origin. PMID:22427849

  2. Differentiating the mTOR inhibitors everolimus and sirolimus in the treatment of tuberous sclerosis complex.

    PubMed

    MacKeigan, Jeffrey P; Krueger, Darcy A

    2015-12-01

    Tuberous sclerosis complex (TSC) is a genetic autosomal dominant disorder characterized by benign tumor-like lesions, called hamartomas, in multiple organ systems, including the brain, skin, heart, kidneys, and lung. These hamartomas cause a diverse set of clinical problems based on their location and often result in epilepsy, learning difficulties, and behavioral problems. TSC is caused by mutations within the TSC1 or TSC2 genes that inactivate the genes' tumor-suppressive function and drive hamartomatous cell growth. In normal cells, TSC1 and TSC2 integrate growth signals and nutrient inputs to downregulate signaling to mammalian target of rapamycin (mTOR), an evolutionarily conserved serine-threonine kinase that controls cell growth and cell survival. The molecular connection between TSC and mTOR led to the clinical use of allosteric mTOR inhibitors (sirolimus and everolimus) for the treatment of TSC. Everolimus is approved for subependymal giant cell astrocytomas and renal angiomyolipomas in patients with TSC. Sirolimus, though not approved for TSC, has undergone considerable investigation to treat various aspects of the disease. Everolimus and sirolimus selectively inhibit mTOR signaling with similar molecular mechanisms, but with distinct clinical profiles. This review differentiates mTOR inhibitors in TSC while describing the molecular mechanisms, pathogenic mutations, and clinical trial outcomes for managing TSC. PMID:26289591

  3. Targeting the mTOR Complex by Everolimus in NRAS Mutant Neuroblastoma.

    PubMed

    Kiessling, Michael K; Curioni-Fontecedro, Alessandra; Samaras, Panagiotis; Lang, Silvia; Scharl, Michael; Aguzzi, Adriano; Oldrige, Derek A; Maris, John M; Rogler, Gerhard

    2016-01-01

    High-risk neuroblastoma remains lethal in about 50% of patients despite multimodal treatment. Recent attempts to identify molecular targets for specific therapies have shown that Neuroblastoma RAS (NRAS) is significantly mutated in a small number of patients. However, few inhibitors for the potential treatment for NRAS mutant neuroblastoma have been investigated so far. In this in-vitro study, we show that MEK inhibitors AZD6244, MEK162 and PD0325901 block cell growth in NRAS mutant neuroblastoma cell lines but not in NRAS wild-type cell lines. Several studies show that mutant NRAS leads to PI3K pathway activation and combined inhibitors of PI3K/mTOR effectively block cell growth. However, we observed the combination of MEK inhibitors with PI3K or AKT inhibitors did not show synergestic effects on cell growth. Thus, we tested single mTOR inhibitors Everolimus and AZD8055. Interestingly, Everolimus and AZD8055 alone were sufficient to block cell growth in NRAS mutant cell lines but not in wild-type cell lines. We found that Everolimus alone induced apoptosis in NRAS mutant neuroblastoma. Furthermore, the combination of mTOR and MEK inhibitors resulted in synergistic growth inhibition. Taken together, our results show that NRAS mutant neuroblastoma can be targeted by clinically available Everolimus alone or in combination with MEK inhibitors which could impact future clinical studies. PMID:26821351

  4. Targeting the mTOR Complex by Everolimus in NRAS Mutant Neuroblastoma

    PubMed Central

    Kiessling, Michael K.; Curioni-Fontecedro, Alessandra; Samaras, Panagiotis; Lang, Silvia; Scharl, Michael; Aguzzi, Adriano; Oldrige, Derek A.; Maris, John M.; Rogler, Gerhard

    2016-01-01

    High-risk neuroblastoma remains lethal in about 50% of patients despite multimodal treatment. Recent attempts to identify molecular targets for specific therapies have shown that Neuroblastoma RAS (NRAS) is significantly mutated in a small number of patients. However, few inhibitors for the potential treatment for NRAS mutant neuroblastoma have been investigated so far. In this in-vitro study, we show that MEK inhibitors AZD6244, MEK162 and PD0325901 block cell growth in NRAS mutant neuroblastoma cell lines but not in NRAS wild-type cell lines. Several studies show that mutant NRAS leads to PI3K pathway activation and combined inhibitors of PI3K/mTOR effectively block cell growth. However, we observed the combination of MEK inhibitors with PI3K or AKT inhibitors did not show synergestic effects on cell growth. Thus, we tested single mTOR inhibitors Everolimus and AZD8055. Interestingly, Everolimus and AZD8055 alone were sufficient to block cell growth in NRAS mutant cell lines but not in wild-type cell lines. We found that Everolimus alone induced apoptosis in NRAS mutant neuroblastoma. Furthermore, the combination of mTOR and MEK inhibitors resulted in synergistic growth inhibition. Taken together, our results show that NRAS mutant neuroblastoma can be targeted by clinically available Everolimus alone or in combination with MEK inhibitors which could impact future clinical studies. PMID:26821351

  5. Everolimus

    MedlinePlus

    Everolimus (Afinitor) is used to treat advanced renal cell carcinoma (RCC; cancer that begins in the kidneys) that has already been treated unsuccessfully with other medications. Everolimus (Afinitor) is ...

  6. Involvement of autophagy in the pharmacological effects of the mTOR inhibitor everolimus in acute kidney injury.

    PubMed

    Nakagawa, Shunsaku; Nishihara, Kumiko; Inui, Ken-ichi; Masuda, Satohiro

    2012-12-01

    Inhibitors of mammalian target of rapamycin (mTOR) have immunosuppressive and anti-cancer effects, but their effects on the progression of kidney disease are not fully understood. Using cells from normal kidney epithelial cell lines, we found that the antiproliferative effects of mTOR inhibitor everolimus accompanied the accumulation of a marker for cellular autophagic activity, the phosphatidylethanolamine-conjugated form of microtubule-associated protein 1 light chain 3 (LC3-II) in cells. We also showed that the primary autophagy factor UNC-51-like kinase 1 was involved in the antiproliferative effects of everolimus. Levels of LC3-II decreased in the kidneys of rats treated with ischemia-reperfusion or cisplatin; however, renal LC3-II levels increased after administration of everolimus to rats subjected to ischemia-reperfusion or cisplatin treatment. Simultaneously, increased signals for kidney injury molecule-1 and single-stranded DNA and decreased signals for Ki-67 in the proximal tubules were observed after treatment with everolimus, indicating that everolimus diminished renal function after acute tubular injury. We also found leakage of LC3 protein into rat urine after treatment with everolimus, and urinary LC3 protein was successfully measured between 0.1 and 500ng/mL by using an enzyme-linked immunosorbent assay. Urinary LC3 levels were increased after administration of everolimus to rats subjected to ischemia-reperfusion or cisplatin treatment, suggesting that renal LC3-II and urinary LC3 protein are new biomarkers for autophagy in acute kidney injury. Taken together, our results demonstrated that the induction of autophagy by everolimus aggravates tubular dysfunction during recovery from kidney injury. PMID:23022334

  7. Use of the mTOR inhibitor everolimus in a patient with multiple manifestations of tuberous sclerosis complex including epilepsy

    PubMed Central

    Wheless, James W.

    2015-01-01

    Tuberous sclerosis complex (TSC) is a genetic disease in which overactivation of mechanistic target of rapamycin (mTOR) signaling leads to the growth of benign hamartomas in multiple organs, including the brain, and is associated with a high rate of epilepsy and neurological deficits. The mTOR inhibitor everolimus has been used in the treatment of subependymal giant cell astrocytomas and renal angiomyolipomas in patients with TSC. This article describes the case of a 13-year-old girl with TSC-associated epilepsy with refractory generalized seizures who initiated treatment with everolimus and experienced subsequent improvement in several TSC manifestations, including a reduction in seizure frequency from clusters of two or three daily to one every 2 to 4 weeks after 1.5 years of treatment. PMID:26543807

  8. mTOR inhibitor-associated stomatitis (mIAS) in three patients with cancer treated with everolimus.

    PubMed

    Kalogirou, Eleni-Marina; Tosios, Konstantinos I; Piperi, Evangelia P; Sklavounou, Alexandra

    2015-01-01

    Mammalian targets of rapamycin inhibitors (mTOR inhibitors, mTORI) are indicated for the management of several cancer types, including hormone receptor--positive or HER2-negative breast cancer, advanced renal cell carcinoma, advanced neuroendocrine tumors of pancreatic origin, and tuberous sclerosis complex-related tumors. Among the most common adverse events of mTORI medication are discrete, large, solitary or multiple, superficial ulcers, almost exclusively situated on nonkeratinized oral mucosa, described as mTORI-associated stomatitis (mIAS). We describe the clinical presentation, course, and management of mIAS in three patients receiving the mTORI everolimus (Afinitor, Novartis, East Hanover, NJ). In two patients, mIAS manifested 9 and 30 days after first using everolimus, respectively, whereas in the third patient, it recurred 3 months after re-introduction of everolimus. Oral rinses with a "magic mouthwash" solution (dexamethasone oral drops solution 2 mg/mL × 10 mL, lidocaine gel 2% × 30 g, doxycycline suspension 50 mg/5 mL × 60 mL, and sucralfate oral suspension 1000 mg/5 mL × 150 mL, dissolved in sodium chloride 0.9% × 2000 mL) four times daily proved helpful in alleviating the symptoms, and the ulcers healed in 4 to 15 days. No side effects were recorded, and dose reduction or discontinuation of everolimus was not necessitated in two cases. PMID:25442249

  9. Inhibition of mTOR pathway by everolimus cooperates with EGFR inhibitors in human tumours sensitive and resistant to anti-EGFR drugs

    PubMed Central

    Bianco, R; Garofalo, S; Rosa, R; Damiano, V; Gelardi, T; Daniele, G; Marciano, R; Ciardiello, F; Tortora, G

    2008-01-01

    Inhibition of a single transduction pathway is often inefficient due to activation of alternative signalling. The mammalian target of rapamycin (mTOR) is a key intracellular kinase integrating proliferation, survival and angiogenic pathways and has been implicated in the resistance to EGFR inhibitors. Thus, mTOR blockade is pursued to interfere at multiple levels with tumour growth. We used everolimus (RAD001) to inhibit mTOR, alone or in combination with anti-EGFR drugs gefitinib or cetuximab, on human cancer cell lines sensitive and resistant to EGFR inhibitors, both in vitro and in vivo. We demonstrated that everolimus is active against EGFR-resistant cancer cell lines and partially restores the ability of EGFR inhibitors to inhibit growth and survival. Everolimus reduces the expression of EGFR-related signalling effectors and VEGF production, inhibiting proliferation and capillary tube formation of endothelial cells, both alone and in combination with gefitinib. Finally, combination of everolimus and gefitinib inhibits growth of GEO and GEO-GR (gefitinib resistant) colon cancer xenografts, activation of signalling proteins and VEGF secretion. Targeting mTOR pathway with everolimus overcomes resistance to EGFR inhibitors and produces a cooperative effect with EGFR inhibitors, providing a valid therapeutic strategy to be tested in a clinical setting. PMID:18319715

  10. In vitro activity of the mTOR inhibitor everolimus, in a large panel of breast cancer cell lines and analysis for predictors of response.

    PubMed

    Hurvitz, Sara A; Kalous, Ondrej; Conklin, Dylan; Desai, Amrita J; Dering, Judy; Anderson, Lee; O'Brien, Neil A; Kolarova, Teodora; Finn, Richard S; Linnartz, Ronald; Chen, David; Slamon, Dennis J

    2015-02-01

    Everolimus (RAD001, Afinitor(®)) is an oral, selective mTOR inhibitor recently approved by the US-FDA in combination with exemestane for treatment of hormone receptor positive advanced breast cancer. To date, no molecular predictors of response to everolimus in breast cancer have been identified. We hypothesized predictive markers could be identified using preclinical models. Using a molecularly characterized panel of human breast cancer and immortalized breast epithelial cell lines, we determined sensitivity to everolimus alone or in combination with ER- or HER2- targeted therapy. Gene expression microarrays and comparative genomic hybridization were performed on the cell lines to identify predictors of response to everolimus. Among 13 everolimus-sensitive cell lines, 10/13(77 %) were luminal, while in 26 resistant cell lines, 16/26(62 %) were non-luminal, and 10/26(38 %) were luminal. Only 3/24 non-luminal lines were sensitive, two of which were HER2+. Everolimus enhanced the anti-proliferative effect of both tamoxifen (TAM) and fulvestrant (FUL) in ER+ breast cancer cell lines, as well as trastuzumab in HER2+ cell lines. Everolimus + FUL but not everolimus + TAM reversed acquired resistance to TAM. Everolimus inhibited mTOR in tested cell lines by decreasing S6 phosphorylation, mediating its anti-proliferative effect by G0/G1 cell cycle arrest and induction of apoptosis. Chromosomal amplifications of AURKA (p value = 0.04) and HER2 (p value = 0.03) were each associated with increased sensitivity to everolimus. Transcript expression microarrays identified GSK3A, PIK3R3, KLF8, and MAPK10 among the genes overexpressed in sensitive luminal lines, while PGP, RPL38, GPT, and GFAP were among the genes overexpressed in resistant luminal cell lines. These preclinical in vitro data provide further support for continued clinical development of everolimus in luminal (ER+ or HER2+) breast cancer in combination with targeted therapies. We identified several potential

  11. mTOR inhibitor therapy: Does it prevent HCC recurrence after liver transplantation?

    PubMed

    Duvoux, Christophe; Toso, Christian

    2015-07-01

    Prevention of hepatocellular carcinoma (HCC) recurrence after liver transplantation is a clinical priority. The importance of the mammalian target of rapamycin (mTOR) pathway in cell growth and survival makes it a logical target for antitumor strategies, as borne out by clinical data in various types of malignancy. A number of studies have indicated that the mTOR inhibitors everolimus and sirolimus suppress cell proliferation and tumor growth in animal models of HCC. Coadministration of an mTOR inhibitor could permit lower dosing of chemotherapeutic agents in HCC management, and trials in non-transplant HCC population are exploring combined used with various agents including sorafenib, the vascular endothelial growth factor inhibitor bevacizumab and conventional agents. In terms of a preventive effect after liver transplantation for HCC, data from retrospective studies and non-randomized prospective analyses in which patients received an mTOR inhibitor with concomitant calcineurin inhibitor therapy have indicated that HCC recurrence rates and overall survival may be improved compared to a standard calcineurin inhibitor regimen. Meta-analyses have supported these findings, but controlled trials are required before any firm conclusions can be drawn. In two of the three randomized trials which have assessed de novo mTOR inhibitor therapy after liver transplantation, there was a numerically lower rate of HCC recurrence by one year post-transplant in patients given an mTOR inhibitor versus the control arm, but absolute numbers were low. Overall, based on the available data from retrospective studies, meta-analyses, and post-hoc assessments of randomized trials, it appears advisable to consider mTOR inhibition-based immunosuppression after transplantation for HCC, particularly in patients who exceed the Milan criteria. Prospective data are awaited. PMID:26071984

  12. Gene expression profiling of response to mTOR inhibitor everolimus in pre-operatively treated post-menopausal women with oestrogen receptor-positive breast cancer.

    PubMed

    Sabine, Vicky S; Sims, Andrew H; Macaskill, E Jane; Renshaw, Lorna; Thomas, Jeremy S; Dixon, J Michael; Bartlett, John M S

    2010-07-01

    There is growing evidence that uncontrolled activation of the PI3K/Akt/mTOR pathway contributes to the development and progression of breast cancer. Inhibition of this pathway has antitumour effects in preclinical studies and efficacy in combination with other agents in breast cancer patients. The aim of this study is to characterise the effects of pre-operative everolimus treatment in primary breast cancer patients and to identify potential molecular predictors of response. Twenty-seven patients with oestrogen receptor (ER)-positive breast cancer completed 11-14 days of neoadjuvant treatment with 5-mg everolimus. Core biopsies were taken before and after treatment and analysed using Illumina HumanRef-8 v2 Expression BeadChips. Changes in proliferation (Ki67) and phospho-AKT were measured on diagnostic core biopsies/resection samples embedded in paraffin by immunohistochemistry to determine response to treatment. Patients that responded to everolimus treatment with significant reductions in proliferation (fall in % Ki67 positive cells) also had significant decreases in the expression of genes involved in cell cycle (P = 8.70E-09) and p53 signalling (P = 0.01) pathways. Highly proliferating tumours that have a poor prognosis exhibited dramatic reductions in the expression of cell cycle genes following everolimus treatment. The genes that most clearly separated responding from non-responding pre-treatment tumours were those involved with protein modification and dephosphorylation, including DYNLRB2, ERBB4, PTPN13, ULK2 and DUSP16. The majority of ER-positive breast tumours treated with everolimus showed a significant reduction in genes involved with proliferation, these may serve as markers of response and predict which patients will derive most benefit from mTOR inhibition.

  13. The mTOR inhibitor Everolimus synergizes with the PI3K inhibitor GDC0941 to enhance anti-tumor efficacy in uveal melanoma

    PubMed Central

    Amirouchene-Angelozzi, Nabil; Frisch-Dit-Leitz, Estelle; Carita, Guillaume; Dahmani, Ahmed; Raymondie, Chloé; Liot, Géraldine; Gentien, David; Némati, Fariba; Decaudin, Didier

    2016-01-01

    Uveal melanoma (UM) is the most frequent malignant ocular tumor in adults. While the primary tumor is efficiently treated by surgery and/or radiotherapy, about one third of UM patients develop metastases, for which no effective treatment is currently available. The PKC, MAPK and PI3K/AKT/mTOR signaling cascades have been shown to be associated with tumor growth. However, none of the compounds against those pathways results in tumor regression when used as single agents. To identify more effective therapeutic strategies for UM patients, we performed a combination screen using seven targeted agents inhibiting PKC, MEK, AKT, PI3K and mTOR in a panel of ten UM cell lines, representative of the UM disease. We identified a strong synergy between the mTOR inhibitor Everolimus and the PI3K inhibitor GDC0941. This combination resulted in an increase in apoptosis in several UM cell lines compared to monotherapies and enhanced the anti-tumor effect of each single agent in two patient-derived xenografts. Furthermore, we showed that the synergism between the two drugs was associated with the relief by GDC0491 of a reactivation of AKT induced by Everolimus. Altogether, our results highlight a novel and effective combination strategy, which could be beneficial for UM patients. PMID:26988753

  14. Everolimus inhibits anti-HLA I antibody-mediated endothelial cell signaling, migration and proliferation more potently than sirolimus.

    PubMed

    Jin, Y-P; Valenzuela, N M; Ziegler, M E; Rozengurt, E; Reed, E F

    2014-04-01

    Antibody (Ab) crosslinking of HLA I molecules on the surface of endothelial cells triggers proliferative and pro-survival intracellular signaling, which is implicated in the process of chronic allograft rejection, also known as transplant vasculopathy (TV). The purpose of this study was to investigate the role of mammalian target of rapamycin (mTOR) in HLA I Ab-induced signaling cascades. Everolimus provides a tool to establish how the mTOR signal network regulates HLA I-mediated migration, proliferation and survival. We found that everolimus inhibits mTOR complex 1 (mTORC1) by disassociating Raptor from mTOR, thereby preventing class I-induced phosphorylation of mTOR, p70S6K, S6RP and 4E-BP1, and resultant class I-stimulated cell migration and proliferation. Furthermore, we found that everolimus inhibits class I-mediated mTORC2 activation (1) by disassociating Rictor and Sin1 from mTOR; (2) by preventing class I-stimulated Akt phosphorylation and (3) by preventing class I-mediated ERK phosphorylation. These results suggest that everolimus is more effective than sirolimus at antagonizing both mTORC1 and mTORC2, the latter of which is critical in endothelial cell functional changes leading to TV in solid organ transplantation after HLA I crosslinking. Our findings point to a potential therapeutic effect of everolimus in prevention of chronic Ab-mediated rejection. PMID:24580843

  15. Anti-Angiogenic/Vascular Effects of the mTOR Inhibitor Everolimus Are Not Detectable by FDG/FLT-PET1

    PubMed Central

    Honer, Michael; Ebenhan, Thomas; Allegrini, Peter R; Ametamey, Simon M; Becquet, Mike; Cannet, Catherine; Lane, Heidi A; O'Reilly, Terence M; Schubiger, Pius A; Sticker-Jantscheff, Melanie; Stumm, Michael; McSheehy, Paul MJ

    2010-01-01

    Noninvasive functional imaging of tumors can provide valuable early-response biomarkers, in particular, for targeted chemotherapy. Using various experimental tumor models, we have investigated the ability of positron emission tomography (PET) measurements of 2-deoxy-2-[18F]fluoro-glucose (FDG) and 3′-deoxy-3′-[18F]fluorothymidine (FLT) to detect response to the allosteric mammalian target of rapamycin (mTOR) inhibitor everolimus. Tumor models were declared sensitive (murine melanoma B16/BL6 and human lung H596) or relatively insensitive (human colon HCT116 and cervical KB31), according to the IC50 values (concentration inhibiting cell growth by 50%) for inhibition of proliferation in vitro (<10 nM and >1 µM, respectively). Everolimus strongly inhibited growth of the sensitive models in vivo but also significantly inhibited growth of the insensitive models, an effect attributable to its known anti-angiogenic/vascular properties. However, although tumor FDG and FLT uptake was significantly reduced in the sensitive models, it was not affected in the insensitive models, suggesting that endothelial-directed effects could not be detected by these PET tracers. Consistent with this hypothesis, in a well-vascularized orthotopic rat mammary tumor model, other antiangiogenic agents also failed to affect FDG uptake, despite inhibiting tumor growth. In contrast, the cytotoxic patupilone, a microtubule stabilizer, blocked tumor growth, and markedly reduced FDG uptake. These results suggest that FDG/FLT-PET may not be a suitable method for early markers of response to antiangiogenic agents and mTOR inhibitors in which anti-angiogenic/vascular effects predominate because the method could provide false-negative responses. These conclusions warrant clinical testing. PMID:20689768

  16. Profile of everolimus in the treatment of tuberous sclerosis complex: an evidence-based review of its place in therapy.

    PubMed

    Capal, Jamie K; Franz, David Neal

    2016-01-01

    Tuberous sclerosis complex (TSC) is a relatively rare genetic disorder, affecting one in 6,000 births. Mammalian target of rapamycin (mTOR) inhibitors, such as everolimus, which have been previously used to prevent solid organ transplant rejection, augment anticancer treatment regimens, and prevent neovascularization of artificial cardiac stents, are now approved for treating TSC-related manifestations, such as subependymal giant cell astrocytomas and renal angiomyolipomas. The use of everolimus in treating subependymal giant cell astrocytomas is supported by long-term Phase II and III clinical trials. Seizures are a common feature in TSC, occurring in up to 96% of patients. While mTOR inhibitors currently do not have regulatory approval in treating this manifestation, small clinical studies have demonstrated beneficial outcomes with everolimus. Further evidence from a forthcoming Phase III clinical study may provide additional support for the use of everolimus for this indication. Also, there are no approved treatments for TSC-associated neuropsychiatric disorders, which include intellectual disability, behavioral difficulties, and autism spectrum disorder, but preclinical data and small studies have suggested that some neuropsychiatric symptoms may be improved through mTOR inhibition therapy. More evidence is needed, particularly regarding safety in young infants. This review focuses on the current evidence supporting the use of everolimus in neurologic and neuropsychiatric manifestations of TSC, and the place of everolimus in therapy. PMID:27601910

  17. Profile of everolimus in the treatment of tuberous sclerosis complex: an evidence-based review of its place in therapy

    PubMed Central

    Capal, Jamie K; Franz, David Neal

    2016-01-01

    Tuberous sclerosis complex (TSC) is a relatively rare genetic disorder, affecting one in 6,000 births. Mammalian target of rapamycin (mTOR) inhibitors, such as everolimus, which have been previously used to prevent solid organ transplant rejection, augment anticancer treatment regimens, and prevent neovascularization of artificial cardiac stents, are now approved for treating TSC-related manifestations, such as subependymal giant cell astrocytomas and renal angiomyolipomas. The use of everolimus in treating subependymal giant cell astrocytomas is supported by long-term Phase II and III clinical trials. Seizures are a common feature in TSC, occurring in up to 96% of patients. While mTOR inhibitors currently do not have regulatory approval in treating this manifestation, small clinical studies have demonstrated beneficial outcomes with everolimus. Further evidence from a forthcoming Phase III clinical study may provide additional support for the use of everolimus for this indication. Also, there are no approved treatments for TSC-associated neuropsychiatric disorders, which include intellectual disability, behavioral difficulties, and autism spectrum disorder, but preclinical data and small studies have suggested that some neuropsychiatric symptoms may be improved through mTOR inhibition therapy. More evidence is needed, particularly regarding safety in young infants. This review focuses on the current evidence supporting the use of everolimus in neurologic and neuropsychiatric manifestations of TSC, and the place of everolimus in therapy.

  18. Profile of everolimus in the treatment of tuberous sclerosis complex: an evidence-based review of its place in therapy

    PubMed Central

    Capal, Jamie K; Franz, David Neal

    2016-01-01

    Tuberous sclerosis complex (TSC) is a relatively rare genetic disorder, affecting one in 6,000 births. Mammalian target of rapamycin (mTOR) inhibitors, such as everolimus, which have been previously used to prevent solid organ transplant rejection, augment anticancer treatment regimens, and prevent neovascularization of artificial cardiac stents, are now approved for treating TSC-related manifestations, such as subependymal giant cell astrocytomas and renal angiomyolipomas. The use of everolimus in treating subependymal giant cell astrocytomas is supported by long-term Phase II and III clinical trials. Seizures are a common feature in TSC, occurring in up to 96% of patients. While mTOR inhibitors currently do not have regulatory approval in treating this manifestation, small clinical studies have demonstrated beneficial outcomes with everolimus. Further evidence from a forthcoming Phase III clinical study may provide additional support for the use of everolimus for this indication. Also, there are no approved treatments for TSC-associated neuropsychiatric disorders, which include intellectual disability, behavioral difficulties, and autism spectrum disorder, but preclinical data and small studies have suggested that some neuropsychiatric symptoms may be improved through mTOR inhibition therapy. More evidence is needed, particularly regarding safety in young infants. This review focuses on the current evidence supporting the use of everolimus in neurologic and neuropsychiatric manifestations of TSC, and the place of everolimus in therapy. PMID:27601910

  19. Systemic and CNS activity of the RET inhibitor vandetanib combined with the mTOR inhibitor everolimus in KIF5B-RET re-arranged non-small cell lung cancer with brain metastases.

    PubMed

    Subbiah, Vivek; Berry, Jenny; Roxas, Michael; Guha-Thakurta, Nandita; Subbiah, Ishwaria Mohan; Ali, Siraj M; McMahon, Caitlin; Miller, Vincent; Cascone, Tina; Pai, Shobha; Tang, Zhenya; Heymach, John V

    2015-07-01

    In-frame fusion KIF5B (the-kinesin-family-5B-gene)-RET transcripts have been characterized in 1-2% of non-small cell lung cancers and are known oncogenic drivers. The RET tyrosine kinase inhibitor, vandetanib, suppresses fusion-induced, anchorage-independent growth activity. In vitro studies have shown that vandetanib is a high-affinity substrate of breast cancer resistance protein (Bcrp1/Abcg2) but is not transported by P-glycoprotein (P-gp), limiting its blood-brain barrier penetration. A co-administration strategy to enhance the brain accumulation of vandetanib by modulating P-gp/Abcb1- and Bcrp1/Abcg2-mediated efflux with mTOR inhibitors, specifically everolimus, was shown to increase the blood-brain barrier penetration. We report the first bench-to-bedside evidence that RET inhibitor combined with an mTOR inhibitor is active against brain-metastatic RET-rearranged lung cancer and the first evidence of blood-brain barrier penetration. A 74-year-old female with progressive adenocarcinoma of the lung (wild-type EGFR and no ALK rearrangement) presented for therapy options. A deletion of 5'RET was revealed by FISH assay, indicating RET-gene rearrangement. Because of progressive disease in the brain, she was enrolled in a clinical trial with vandetanib and everolimus (NCT01582191). Comprehensive genomic profiling revealed fusion of KIF5B (the-kinesin-family-5B-gene) and RET, in addition to AKT2 gene amplification. After two cycles of therapy a repeat MRI brain showed a decrease in the intracranial disease burden and PET/CT showed systemic response as well. Interestingly, AKT2 amplification seen is a critical component of the PI3K/mTOR pathway, alterations of which has been associated with both de novo and acquired resistance to targeted therapy. The addition of everolimus may have both overcome the AKT2 amplification to produce a response in addition to its direct effects on the RET gene. Our case report forms the first evidence of blood-brain barrier penetration by

  20. Systemic and CNS activity of the RET inhibitor vandetanib combined with the mTOR inhibitor everolimus in KIF5B-RET re-arranged non-small cell lung cancer with brain metastases.

    PubMed

    Subbiah, Vivek; Berry, Jenny; Roxas, Michael; Guha-Thakurta, Nandita; Subbiah, Ishwaria Mohan; Ali, Siraj M; McMahon, Caitlin; Miller, Vincent; Cascone, Tina; Pai, Shobha; Tang, Zhenya; Heymach, John V

    2015-07-01

    In-frame fusion KIF5B (the-kinesin-family-5B-gene)-RET transcripts have been characterized in 1-2% of non-small cell lung cancers and are known oncogenic drivers. The RET tyrosine kinase inhibitor, vandetanib, suppresses fusion-induced, anchorage-independent growth activity. In vitro studies have shown that vandetanib is a high-affinity substrate of breast cancer resistance protein (Bcrp1/Abcg2) but is not transported by P-glycoprotein (P-gp), limiting its blood-brain barrier penetration. A co-administration strategy to enhance the brain accumulation of vandetanib by modulating P-gp/Abcb1- and Bcrp1/Abcg2-mediated efflux with mTOR inhibitors, specifically everolimus, was shown to increase the blood-brain barrier penetration. We report the first bench-to-bedside evidence that RET inhibitor combined with an mTOR inhibitor is active against brain-metastatic RET-rearranged lung cancer and the first evidence of blood-brain barrier penetration. A 74-year-old female with progressive adenocarcinoma of the lung (wild-type EGFR and no ALK rearrangement) presented for therapy options. A deletion of 5'RET was revealed by FISH assay, indicating RET-gene rearrangement. Because of progressive disease in the brain, she was enrolled in a clinical trial with vandetanib and everolimus (NCT01582191). Comprehensive genomic profiling revealed fusion of KIF5B (the-kinesin-family-5B-gene) and RET, in addition to AKT2 gene amplification. After two cycles of therapy a repeat MRI brain showed a decrease in the intracranial disease burden and PET/CT showed systemic response as well. Interestingly, AKT2 amplification seen is a critical component of the PI3K/mTOR pathway, alterations of which has been associated with both de novo and acquired resistance to targeted therapy. The addition of everolimus may have both overcome the AKT2 amplification to produce a response in addition to its direct effects on the RET gene. Our case report forms the first evidence of blood-brain barrier penetration by

  1. Regression of Cardiac Rhabdomyomas in a Neonate after Everolimus Treatment

    PubMed Central

    Bornaun, Helen; Öztarhan, Kazım; Erener-Ercan, Tugba; Dedeoğlu, Reyhan; Tugcu, Deniz; Aydoğmuş, Çiğdem; Cetinkaya, Merih; Kavuncuoglu, Sultan

    2016-01-01

    Cardiac rhabdomyoma often shows spontaneous regression and usually requires only close follow-up. However, patients with symptomatic inoperable rhabdomyomas may be candidates for everolimus treatment. Our patient had multiple inoperable cardiac rhabdomyomas causing serious left ventricle outflow-tract obstruction that showed a dramatic reduction in the size after everolimus therapy, a mammalian target of rapamycin (mTOR) inhibitor. After discontinuation of therapy, an increase in the diameter of masses occurred and everolimus was restarted. After 6 months of treatment, rhabdomyomas decreased in size and therapy was stopped. In conclusion, everolimus could be a possible novel therapy for neonates with clinically significant rhabdomyomas. PMID:27429821

  2. Everolimus and Malignancy after Solid Organ Transplantation: A Clinical Update

    PubMed Central

    De Simone, Paolo

    2016-01-01

    Malignancy after solid organ transplantation remains a major cause of posttransplant mortality. The mammalian target of rapamycin (mTOR) inhibitor class of immunosuppressants exerts various antioncogenic effects, and the mTOR inhibitor everolimus is licensed for the treatment of several solid cancers. In kidney transplantation, evidence from registry studies indicates a lower rate of de novo malignancy under mTOR inhibition, with some potentially supportive data from randomized trials of everolimus. Case reports and small single-center series have suggested that switch to everolimus may be beneficial following diagnosis of posttransplant malignancy, particularly for Kaposi's sarcoma and nonmelanoma skin cancer, but prospective studies are lacking. A systematic review has shown mTOR inhibition to be associated with a significantly lower rate of hepatocellular carcinoma (HCC) recurrence versus standard calcineurin inhibitor therapy. One meta-analysis has concluded that patients with nontransplant HCC experience a low but significant survival benefit under everolimus monotherapy, so far unconfirmed in a transplant population. Data are limited in heart transplantation, although observational data and case reports have indicated that introduction of everolimus is helpful in reducing the recurrence of skin cancers. Overall, it can be concluded that, in certain settings, everolimus appears a promising option to lessen the toll of posttransplant malignancy.

  3. Everolimus in advanced pancreatic neuroendocrine tumors: the clinical experience.

    PubMed

    Yao, James C; Phan, Alexandria T; Jehl, Valentine; Shah, Gaurav; Meric-Bernstam, Funda

    2013-03-01

    The incidence of neuroendocrine tumors (NET) has increased dramatically in the past 30 years. This information has revitalized basic and clinical research into the molecular biology of NET and has resulted in the recent approval of new therapies for pancreatic NET (pNET), including the oral inhibitor of the mTOR everolimus. Everolimus significantly improved progression-free survival among patients with pNET in the phase III RADIANT-3 study. Here, we review the clinical studies showing the efficacy of everolimus in pNET and summarize the translational science from these studies. To understand the mechanisms of resistance and cause of treatment failure, we compared the type of progression events observed in the everolimus and placebo arms of the RADIANT-3 study. Comparison of the everolimus arm to the placebo arm indicated the fractions of progression events due to new metastasis only (21% vs. 22%), growth of preexisting lesions only (54% vs. 49%), and new metastasis along with growth of preexisting lesions (24% vs. 27%) were similar. These results suggest that although everolimus delays disease progression in patients with pNET, patients who experience disease progression while on everolimus do not appear to have a more aggressive metastatic phenotype than those whose disease progresses while on placebo.

  4. Everolimus exhibits anti-tumorigenic activity in obesity-induced ovarian cancer

    PubMed Central

    Guo, Hui; Zhong, Yan; Jackson, Amanda L.; Clark, Leslie H.; Kilgore, Josh; Zhang, Lu; Han, Jianjun; Sheng, Xiugui; Gilliam, Timothy P.; Gehrig, Paola A.; Zhou, Chunxiao; Bae, Victoria L.

    2016-01-01

    Everolimus inhibits mTOR kinase activity and its downstream targets by acting on mTORC1 and has anti-tumorigenic activity in ovarian cancer. Clinical and epidemiologic data find that obesity is associated with worse outcomes in ovarian cancer. In addition, obesity leads to hyperactivation of the mTOR pathway in epithelial tissues, suggesting that mTOR inhibitors may be a logical choice for treatment in obesity-driven cancers. However, it remains unclear if obesity impacts the effect of everolimus on tumor growth in ovarian cancer. The present study was aimed at evaluating the effects of everolimus on cytotoxicity, cell metabolism, apoptosis, cell cycle, cell stress and invasion in human ovarian cancer cells. A genetically engineered mouse model of serous ovarian cancer fed a high fat diet or low fat diet allowed further investigation into the inter-relationship between everolimus and obesity in vivo. Everolimus significantly inhibited cellular proliferation, induced cell cycle G1 arrest and apoptosis, reduced invasion and caused cellular stress via inhibition of mTOR pathways in vitro. Hypoglycemic conditions enhanced the sensitivity of cells to everolimus through the disruption of glycolysis. Moreover, everolimus was found to inhibit ovarian tumor growth in both obese and lean mice. This reduction coincided with a decrease in expression of Ki-67 and phosphorylated-S6, as well as an increase in cleaved caspase 3 and phosphorylated-AKT. Metabolite profiling revealed that everolimus was able to alter tumor metabolism through different metabolic pathways in the obese and lean mice. Our findings support that everolimus may be a promising therapeutic agent for obesity-driven ovarian cancers. PMID:26959121

  5. Potential therapeutic effects of the MTOR inhibitors for preventing ageing and progeria‐related disorders

    PubMed Central

    Evangelisti, Camilla; Cenni, Vittoria

    2016-01-01

    The mammalian target of rapamycin (mTOR) pathway is an highly conserved signal transduction axis involved in many cellular processes, such as cell growth, survival, transcription, translation, apoptosis, metabolism, motility and autophagy. Recently, this signalling pathway has come to the attention of the scientific community owing to the unexpected finding that inhibition of mTOR by rapamycin, an antibiotic with immunosuppressant and chemotherapeutic properties, extends lifespan in diverse animal models. Moreover, rapamycin has been reported to rescue the cellular phenotype in a progeroid syndrome [Hutchinson–Gilford Progeria syndrome (HGPS)] that recapitulates most of the traits of physiological ageing. The promising perspectives raised by these results warrant a better understanding of mTOR signalling and the potential applications of mTOR inhibitors to counteract ageing‐associated diseases and increase longevity. This review is focused on these issues. PMID:26952863

  6. Pivotal Role of mTOR Signaling in Hepatocellular Carcinoma

    PubMed Central

    Villanueva, Augusto; Chiang, Derek Y.; Newell, Pippa; Peix, Judit; Thung, Swan; Alsinet, Clara; Tovar, Victoria; Roayaie, Sasan; Minguez, Beatriz; Sole, Manel; Battiston, Carlo; van Laarhoven, Stijn; Fiel, Maria I; Di Feo, Analisa; Hoshida, Yujin; Yea, Steven; Toffanin, Sara; Ramos, Alex; Martignetti, John A.; Mazzaferro, Vincenzo; Bruix, Jordi; Waxman, Samuel; Schwartz, Myron; Meyerson, Matthew; Friedman, Scott L.; Llovet, Josep M.

    2008-01-01

    BACKGROUND The advent of targeted therapies in hepatocellular carcinoma (HCC) has underscored the importance of pathway characterization to identify novel molecular targets for treatment. Based on its role in cell growth and differentiation, we evaluated mTOR signaling activation in human HCC, as well as the anti-tumoral effect of a dual-level blockade of the mTOR pathway. METHODS The mTOR pathway was assessed using integrated data from mutation analysis (direct sequencing), DNA copy number changes (SNP-array), mRNA levels (qRT-PCR and gene expression microarray), and protein activation (immunostaining) in 351 human samples, including HCC (n=314), and non-tumoral tissue (n=37). Effects of dual blockade of mTOR signaling using a rapamycin analog (everolimus) and an EGFR/VEGFR inhibitor (AEE788) were evaluated in liver cancer cell lines, and in a tumor xenograft model. RESULTS Aberrant mTOR signaling (phosphorylated-RPS6) was present in half of the cases, associated with IGF pathway activation, EGF upregulation, and PTEN dysregulation. PTEN and PI3KCA-B mutations were rare events. Chromosomal gains in RICTOR (25% of patients) and positive pRPS6 staining correlated with recurrence. RICTOR-specific siRNA downregulation reduced tumor cell viability in vitro. Blockage of mTOR signaling with everolimus in vitro and in a xenograft model decelerated tumor growth and increased survival. This effect was enhanced in vivo after EGFR blockade. CONCLUSIONS MTOR signaling has a critical role in the pathogenesis of HCC, with evidence for the role of RICTOR in tumor oncogenesis. MTOR blockade with everolimus is effective in vivo. These findings establish a rationale for targeting mTOR pathway in clinical trials in HCC. PMID:18929564

  7. Prolonged clinical benefit of everolimus therapy in the management of high-grade pancreatic neuroendocrine carcinoma.

    PubMed

    Fonseca, Paula J; Uriol, Esther; Galván, José A; Alvarez, Carlos; Pérez, Quionia; Villanueva, Noemi; Berros, José P; Izquierdo, Marta; Viéitez, José M

    2013-01-01

    Treatment options for patients with high-grade pancreatic neuroendocrine tumors (pNET) are limited, especially for those with progressive disease and for those who experience treatment failure. Everolimus, an oral inhibitor of mammalian target of rapamycin (mTOR), has been approved for the treatment of patients with low- or intermediate-grade advanced pNET. In the randomized phase III RADIANT-3 study in patients with low- or intermediate-grade advanced pNET, everolimus significantly increased progression-free survival (PFS) and decreased the relative risk for disease progression by 65% over placebo. This case report describes a heavily pretreated patient with high-grade pNET and liver and peritoneal metastases who achieved prolonged PFS, clinically relevant partial radiologic tumor response, and resolution of constitutional symptoms with improvement in Karnofsky performance status while receiving a combination of everolimus and octreotide long-acting repeatable (LAR). Radiologic and clinical responses were maintained for 19 months, with minimal toxicity over the course of treatment. This case supports the findings that the combination of everolimus plus octreotide LAR may be considered for use in patients with high-grade pNET and progressive disease. Although behavior and aggressiveness are different between low- or intermediate-grade and high-grade pNET, some high-grade pNET may express mTOR; hence, everolimus should be considered in a clinical trial.

  8. Prolonged Clinical Benefit of Everolimus Therapy in the Management of High-Grade Pancreatic Neuroendocrine Carcinoma

    PubMed Central

    Fonseca, Paula J.; Uriol, Esther; Galván, José A.; Álvarez, Carlos; Pérez, Quionia; Villanueva, Noemi; Berros, José P.; Izquierdo, Marta; Viéitez, José M.

    2013-01-01

    Treatment options for patients with high-grade pancreatic neuroendocrine tumors (pNET) are limited, especially for those with progressive disease and for those who experience treatment failure. Everolimus, an oral inhibitor of mammalian target of rapamycin (mTOR), has been approved for the treatment of patients with low- or intermediate-grade advanced pNET. In the randomized phase III RADIANT-3 study in patients with low- or intermediate-grade advanced pNET, everolimus significantly increased progression-free survival (PFS) and decreased the relative risk for disease progression by 65% over placebo. This case report describes a heavily pretreated patient with high-grade pNET and liver and peritoneal metastases who achieved prolonged PFS, clinically relevant partial radiologic tumor response, and resolution of constitutional symptoms with improvement in Karnofsky performance status while receiving a combination of everolimus and octreotide long-acting repeatable (LAR). Radiologic and clinical responses were maintained for 19 months, with minimal toxicity over the course of treatment. This case supports the findings that the combination of everolimus plus octreotide LAR may be considered for use in patients with high-grade pNET and progressive disease. Although behavior and aggressiveness are different between low- or intermediate-grade and high-grade pNET, some high-grade pNET may express mTOR; hence, everolimus should be considered in a clinical trial. PMID:24019785

  9. Future perspectives for mTOR inhibitors in renal cell cancer treatment.

    PubMed

    Czarnecka, Anna M; Kornakiewicz, Anna; Lian, Fei; Szczylik, Cezary

    2015-01-01

    Everolimus is a mTOR inhibitor that demonstrates antitumor and antiangiogenic activities. In a randomized Phase III trial, patients with metastatic renal cell carcinoma who progressed on sunitinib/sorafenib were treated with everolimus and showed significant improvement in progression-free survival compared with best supportive care. Novel approaches in treatment are expected to ensure less toxic therapies and increase efficacy of everolimus. To provide a new perspective for mTOR inhibitor research and therapy, we discuss renal cell carcinoma cancer stem cells as a potential target for mTOR inhibitors and present new concepts on emerging antiangiogenic therapies. Finally, we point why systems biology approach with reverse molecular engineering may also contribute to the field of drug discovery in renal cell carcinoma.

  10. Everolimus in the management of metastatic renal cell carcinoma: an evidence-based review of its place in therapy

    PubMed Central

    Buti, Sebastiano; Leonetti, Alessandro; Dallatomasina, Alice; Bersanelli, Melissa

    2016-01-01

    Introduction Renal cell carcinoma (RCC) is the most common type of kidney cancer in adults, and its pathogenesis is strictly related to altered cellular response to hypoxia, in which mTOR signaling pathway is implicated. Everolimus, an mTOR serine/threonine kinase inhibitor, represents a therapeutic option for the treatment of advanced RCC. Aim The objective of this article is to review the evidence for the treatment of metastatic RCC with everolimus. Evidence review Everolimus was approved for second- and third-line therapy in patients with advanced RCC according to the results of a Phase III pivotal trial that demonstrated a benefit in median progression-free survival of ~2 months compared to placebo after failure of previous lines of therapy, of which at least one was an anti-VEGFR tyrosine kinase inhibitor (TKI). The role of this drug in first-line setting has been investigated in Phase II trials, with no significant clinical benefit, even in combination with bevacizumab. Everolimus activity in non-clear cell RCC is supported by two randomized Phase II trials that confirmed the benefit in second-line setting but not in first line. Recently, two randomized Phase III trials (METEOR and CheckMate 025) demonstrated the inferiority of everolimus in second-line setting compared to the TKI cabozantinib and to the immune checkpoint inhibitor nivolumab, respectively. Moreover, a recent Phase II study demonstrated a significant benefit for the second-line combination treatment with everolimus plus lenvatinib (a novel TKI) in terms of progression-free survival and overall survival compared to the single-agent everolimus. Basing on preclinical data, the main downstream effectors of mTOR cascade, S6RP and its phosphorylated form, could be good predictive biomarkers of response to everolimus. The safety profile of the drug is favorable, with a good cost-effectiveness compared to second-line sorafenib or axitinib, and no significant impact on the quality of life of treated

  11. Everolimus in the management of metastatic renal cell carcinoma: an evidence-based review of its place in therapy

    PubMed Central

    Buti, Sebastiano; Leonetti, Alessandro; Dallatomasina, Alice; Bersanelli, Melissa

    2016-01-01

    Introduction Renal cell carcinoma (RCC) is the most common type of kidney cancer in adults, and its pathogenesis is strictly related to altered cellular response to hypoxia, in which mTOR signaling pathway is implicated. Everolimus, an mTOR serine/threonine kinase inhibitor, represents a therapeutic option for the treatment of advanced RCC. Aim The objective of this article is to review the evidence for the treatment of metastatic RCC with everolimus. Evidence review Everolimus was approved for second- and third-line therapy in patients with advanced RCC according to the results of a Phase III pivotal trial that demonstrated a benefit in median progression-free survival of ~2 months compared to placebo after failure of previous lines of therapy, of which at least one was an anti-VEGFR tyrosine kinase inhibitor (TKI). The role of this drug in first-line setting has been investigated in Phase II trials, with no significant clinical benefit, even in combination with bevacizumab. Everolimus activity in non-clear cell RCC is supported by two randomized Phase II trials that confirmed the benefit in second-line setting but not in first line. Recently, two randomized Phase III trials (METEOR and CheckMate 025) demonstrated the inferiority of everolimus in second-line setting compared to the TKI cabozantinib and to the immune checkpoint inhibitor nivolumab, respectively. Moreover, a recent Phase II study demonstrated a significant benefit for the second-line combination treatment with everolimus plus lenvatinib (a novel TKI) in terms of progression-free survival and overall survival compared to the single-agent everolimus. Basing on preclinical data, the main downstream effectors of mTOR cascade, S6RP and its phosphorylated form, could be good predictive biomarkers of response to everolimus. The safety profile of the drug is favorable, with a good cost-effectiveness compared to second-line sorafenib or axitinib, and no significant impact on the quality of life of treated

  12. Next-generation sequencing reveals somatic mutations that confer exceptional response to everolimus

    PubMed Central

    Kim, Sangwoo; Kim, Sora; Ali, Siraj M.; Greenbowe, Joel R.; Yang, In Seok; Kwon, Nak-Jung; Lee, Jae Lyun; Ryu, Min-Hee; Ahn, Jin-Hee; Lee, Jeeyun; Lee, Min Goo; Kim, Hyo Song; Kim, Hyunki; Kim, Hye Ryun; Moon, Yong Wha; Chung, Hyun Cheol; Kim, Joo-Hang; Kang, Yoon-Koo; Cho, Byoung Chul

    2016-01-01

    Background Given the modest responses to everolimus, a mTOR inhibitor, in multiple tumor types, there is a pressing need to identify predictive biomarkers for this drug. Using targeted ultra-deep sequencing, we aimed to explore genomic alterations that confer extreme sensitivity to everolimus. Results We collected formalin-fixed paraffin-embedded tumor/normal pairs from 39 patients (22 with exceptional clinical benefit, 17 with no clinical benefit) who were treated with everolimus across various tumor types (13 gastric cancers, 15 renal cell carcinomas, 2 thyroid cancers, 2 head and neck cancer, and 7 sarcomas). Ion AmpliSeqTM Comprehensive Cancer Panel was used to identify alterations across all exons of 409 target genes. Tumors were sequenced to a median coverage of 552x. Cancer genomes are characterized by 219 somatic single-nucleotide variants (181 missense, 9 nonsense, 7 splice-site) and 22 frameshift insertions/deletions, with a median of 2.1 mutations per Mb (0 to 12.4 mutations per Mb). Overall, genomic alterations with activating effect on mTOR signaling were identified in 10 of 22 (45%) patients with clinical benefit and these include MTOR, TSC1, TSC2, NF1, PIK3CA and PIK3CG mutations. Recurrently mutated genes in chromatin remodeling genes (BAP1; n = 2, 12%) and receptor tyrosine kinase signaling (FGFR4; n = 2, 12%) were noted only in patients without clinical benefit. Conclusions Regardless of different cancer types, mTOR-pathway-activating mutations confer sensitivity to everolimus. Targeted sequencing of mTOR pathway genes facilitates identification of potential candidates for mTOR inhibitors. PMID:26859683

  13. Clinical evidence of the efficacy of everolimus and its potential in the treatment of breast cancer

    PubMed Central

    Saksena, Rujuta; Wong, Serena T

    2013-01-01

    The PI3K/Akt/mTOR (phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin) pathway regulates several key cellular functions and its dysregulation creates an environment that promotes tumorigenesis as well as resistance to therapy. The mTOR inhibitor everolimus has emerged as a promising agent in the treatment of breast cancer and was recently approved in combination with exemestane for advanced hormone receptor–positive disease after progression on a nonsteroidal aromatase inhibitor. Everolimus may also be effective in combination with cytotoxic and human epidermal growth factor receptor-2-directed therapies for the treatment of other subtypes of breast cancer. This paper highlights preclinical and clinical data that have emerged on the role of mTOR inhibition in breast cancer. Although generally well tolerated, everolimus carries a unique side effect profile of which both patients and providers should be made aware. Recommendations related to the administration of everolimus in the clinical setting are also discussed. PMID:24648755

  14. mTOR inhibition prevents rapid-onset of carcinogen-induced malignancies in a novel inducible HPV-16 E6/E7 mouse model.

    PubMed

    Callejas-Valera, Juan Luis; Iglesias-Bartolome, Ramiro; Amornphimoltham, Panomwat; Palacios-Garcia, Julia; Martin, Daniel; Califano, Joseph A; Molinolo, Alfredo A; Gutkind, J Silvio

    2016-10-01

    The rising incidence of human papillomavirus (HPV)-associated malignancies, especially for oropharyngeal cancers, has highlighted the urgent need to understand how the interplay between high-risk HPV oncogenes and carcinogenic exposure results in squamous cell carcinoma (SCC) development. Here, we describe an inducible mouse model expressing high risk HPV-16 E6/E7 oncoproteins in adults, bypassing the impact of these viral genes during development. HPV-16 E6/E7 genes were targeted to the basal squamous epithelia in transgenic mice using a doxycycline inducible cytokeratin 5 promoter (cK5-rtTA) system. After doxycycline induction, both E6 and E7 were highly expressed, resulting in rapid epidermal hyperplasia with a remarkable expansion of the proliferative cell compartment to the suprabasal layers. Surprisingly, in spite of the massive growth of epithelial cells and their stem cell progenitors, HPV-E6/E7 expression was not sufficient to trigger mTOR activation, a key oncogenic driver in HPV-associated malignancies, and malignant progression to SCC. However, these mice develop SCC rapidly after a single exposure to a skin carcinogen, DMBA, which was increased by the prolonged exposure to a tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). Thus, only few oncogenic hits may be sufficient to induce cancer in E6/E7 expressing cells. All HPV-E6/E7 expressing SCC lesions exhibited increased mTOR activation. Remarkably, rapamycin, an mTOR inhibitor, abolished tumor development when administered to HPV-E6/E7 mice prior to DMBA exposure. Our findings revealed that mTOR inhibition protects HPV-E6/E7 expressing tissues form SCC development upon carcinogen exposure, thus supporting the potential clinical use of mTOR inhibitors as a molecular targeted approach for prevention of HPV-associated malignancies.

  15. Antagonistic effects of chloroquine on autophagy occurrence potentiate the anticancer effects of everolimus on renal cancer cells

    PubMed Central

    Grimaldi, A; Santini, D; Zappavigna, S; Lombardi, A; Misso, G; Boccellino, M; Desiderio, V; Vitiello, P P; Di Lorenzo, G; Zoccoli, A; Pantano, F; Caraglia, M

    2015-01-01

    Renal cell carcinoma is an aggressive disease often asymptomatic and weakly chemo-radiosensitive. Currently, new biologic drugs are used among which everolimus, an mTOR inhibitor, that has been approved for second-line therapy. Since mTOR is involved in the control of autophagy, its antitumor capacity is often limited. In this view, chloroquine, a 4-alkylamino substituted quinoline family member, is an autophagy inhibitor that blocks the fusion of autophagosomes and lysosomes. In the present study, we evaluated the effects of everolimus alone or in combination with chloroquine on renal cancer cell viability and verified possible synergism. Our results demonstrate that renal cancer cells are differently sensitive to everolimus and chloroquine and the pharmacological combination everolimus/chloroquine was strongly synergistic inducing cell viability inhibition. In details, the pharmacological synergism occurs when chloroquine is administered before everolimus. In addition, we found a flow autophagic block and shift of death mechanisms to apoptosis. This event was associated with decrease of Beclin-1/Bcl-2 complex and parallel reduction of anti-apoptotic protein Bcl-2 in combined treatment. At last, we found that the enhancement of apoptosis induced by drug combination occurs through the intrinsic mitochondrial apoptotic pathway activation, while the extrinsic pathway is involved only partly following its activation by chloroquine. These results provide the basis for new therapeutic strategies for the treatment of renal cell carcinoma after appropriate clinical trial. PMID:25866016

  16. Antagonistic effects of chloroquine on autophagy occurrence potentiate the anticancer effects of everolimus on renal cancer cells.

    PubMed

    Grimaldi, A; Santini, D; Zappavigna, S; Lombardi, A; Misso, G; Boccellino, M; Desiderio, V; Vitiello, P P; Di Lorenzo, G; Zoccoli, A; Pantano, F; Caraglia, M

    2015-01-01

    Renal cell carcinoma is an aggressive disease often asymptomatic and weakly chemo-radiosensitive. Currently, new biologic drugs are used among which everolimus, an mTOR inhibitor, that has been approved for second-line therapy. Since mTOR is involved in the control of autophagy, its antitumor capacity is often limited. In this view, chloroquine, a 4-alkylamino substituted quinoline family member, is an autophagy inhibitor that blocks the fusion of autophagosomes and lysosomes. In the present study, we evaluated the effects of everolimus alone or in combination with chloroquine on renal cancer cell viability and verified possible synergism. Our results demonstrate that renal cancer cells are differently sensitive to everolimus and chloroquine and the pharmacological combination everolimus/chloroquine was strongly synergistic inducing cell viability inhibition. In details, the pharmacological synergism occurs when chloroquine is administered before everolimus. In addition, we found a flow autophagic block and shift of death mechanisms to apoptosis. This event was associated with decrease of Beclin-1/Bcl(-)2 complex and parallel reduction of anti-apoptotic protein Bcl(-)2 in combined treatment. At last, we found that the enhancement of apoptosis induced by drug combination occurs through the intrinsic mitochondrial apoptotic pathway activation, while the extrinsic pathway is involved only partly following its activation by chloroquine. These results provide the basis for new therapeutic strategies for the treatment of renal cell carcinoma after appropriate clinical trial. PMID:25866016

  17. Antagonistic effects of chloroquine on autophagy occurrence potentiate the anticancer effects of everolimus on renal cancer cells.

    PubMed

    Grimaldi, A; Santini, D; Zappavigna, S; Lombardi, A; Misso, G; Boccellino, M; Desiderio, V; Vitiello, P P; Di Lorenzo, G; Zoccoli, A; Pantano, F; Caraglia, M

    2015-01-01

    Renal cell carcinoma is an aggressive disease often asymptomatic and weakly chemo-radiosensitive. Currently, new biologic drugs are used among which everolimus, an mTOR inhibitor, that has been approved for second-line therapy. Since mTOR is involved in the control of autophagy, its antitumor capacity is often limited. In this view, chloroquine, a 4-alkylamino substituted quinoline family member, is an autophagy inhibitor that blocks the fusion of autophagosomes and lysosomes. In the present study, we evaluated the effects of everolimus alone or in combination with chloroquine on renal cancer cell viability and verified possible synergism. Our results demonstrate that renal cancer cells are differently sensitive to everolimus and chloroquine and the pharmacological combination everolimus/chloroquine was strongly synergistic inducing cell viability inhibition. In details, the pharmacological synergism occurs when chloroquine is administered before everolimus. In addition, we found a flow autophagic block and shift of death mechanisms to apoptosis. This event was associated with decrease of Beclin-1/Bcl(-)2 complex and parallel reduction of anti-apoptotic protein Bcl(-)2 in combined treatment. At last, we found that the enhancement of apoptosis induced by drug combination occurs through the intrinsic mitochondrial apoptotic pathway activation, while the extrinsic pathway is involved only partly following its activation by chloroquine. These results provide the basis for new therapeutic strategies for the treatment of renal cell carcinoma after appropriate clinical trial.

  18. Everolimus in renal cell carcinoma.

    PubMed

    Wang, Y

    2010-08-01

    Everolimus (also known as RAD-001; Afinitor®) is an orally active inhibitor of the intracellular protein kinase mammalian target of rapamycin. The U.S. Food and Drug Administration and the European Medicines Agency recently approved everolimus for the treatment of advanced renal cell carcinoma (RCC) on the basis of the results of a randomized phase III clinical trial. In the trial, 10 mg daily everolimus was effective and well tolerated by patients with advanced RCC, whose disease had progressed while under the treatment with sunitinib and/or sorafenib. Everolimus treatment led to 36% of 6-month progression-free survival (PFS) rate and 31% of 3-month PFS rate. Most of the adverse events were mild to moderate (grade 1-2) in severity. The most frequent grade 3-4 adverse events were stomatitis, fatigue, pneumonitis and infections. Clinical trials on everolimus in combination with sunitinib, sorafenib, imatinib and vatalanib for the treatment of RCC are ongoing. PMID:20830316

  19. Lipopolysaccharide Exposure Induces Maternal Hypozincemia, and Prenatal Zinc Treatment Prevents Autistic-Like Behaviors and Disturbances in the Striatal Dopaminergic and mTOR Systems of Offspring

    PubMed Central

    Kirsten, Thiago Berti; Chaves-Kirsten, Gabriela P.; Bernardes, Suene; Scavone, Cristoforo; Sarkis, Jorge E.; Bernardi, Maria Martha; Felicio, Luciano F.

    2015-01-01

    Autism is characterized by social deficits, repetitive behaviors, and cognitive inflexibility. The risk factors appear to include genetic and environmental conditions, such as prenatal infections and maternal dietary factors. Previous investigations by our group have demonstrated that prenatal exposure to lipopolysaccharide (LPS), which mimics infection by gram-negative bacteria, induces autistic-like behaviors. To understand the causes of autistic-like behaviors, we evaluated maternal serum metal concentrations, which are involved in intrauterine development and infection/inflammation. We identified reduced maternal levels of zinc, magnesium, selenium and manganese after LPS exposure. Because LPS induced maternal hypozincemia, we treated dams with zinc in an attempt to prevent or ease the impairments in the offspring. We evaluated the social and cognitive autistic-like behaviors and brain tissues of the offspring to identify the central mechanism that triggers the development of autism. Prenatal LPS exposure impaired play behaviors and T-maze spontaneous alternations, i.e., it induced autistic-like behaviors. Prenatal LPS also decreased tyrosine hydroxylase levels and increased the levels of mammalian target of rapamycin (mTOR) in the striatum. Thus, striatal dopaminergic impairments may be related to autism. Moreover, excessive signaling through the mTOR pathway has been considered a biomarker of autism, corroborating our rat model of autism. Prenatal zinc treatment prevented these autistic-like behaviors and striatal dopaminergic and mTOR disturbances in the offspring induced by LPS exposure. The present findings revealed a possible relation between maternal hypozincemia during gestation and the onset of autism. Furthermore, prenatal zinc administration appears to have a beneficial effect on the prevention of autism. PMID:26218250

  20. Lipopolysaccharide Exposure Induces Maternal Hypozincemia, and Prenatal Zinc Treatment Prevents Autistic-Like Behaviors and Disturbances in the Striatal Dopaminergic and mTOR Systems of Offspring.

    PubMed

    Kirsten, Thiago Berti; Chaves-Kirsten, Gabriela P; Bernardes, Suene; Scavone, Cristoforo; Sarkis, Jorge E; Bernardi, Maria Martha; Felicio, Luciano F

    2015-01-01

    Autism is characterized by social deficits, repetitive behaviors, and cognitive inflexibility. The risk factors appear to include genetic and environmental conditions, such as prenatal infections and maternal dietary factors. Previous investigations by our group have demonstrated that prenatal exposure to lipopolysaccharide (LPS), which mimics infection by gram-negative bacteria, induces autistic-like behaviors. To understand the causes of autistic-like behaviors, we evaluated maternal serum metal concentrations, which are involved in intrauterine development and infection/inflammation. We identified reduced maternal levels of zinc, magnesium, selenium and manganese after LPS exposure. Because LPS induced maternal hypozincemia, we treated dams with zinc in an attempt to prevent or ease the impairments in the offspring. We evaluated the social and cognitive autistic-like behaviors and brain tissues of the offspring to identify the central mechanism that triggers the development of autism. Prenatal LPS exposure impaired play behaviors and T-maze spontaneous alternations, i.e., it induced autistic-like behaviors. Prenatal LPS also decreased tyrosine hydroxylase levels and increased the levels of mammalian target of rapamycin (mTOR) in the striatum. Thus, striatal dopaminergic impairments may be related to autism. Moreover, excessive signaling through the mTOR pathway has been considered a biomarker of autism, corroborating our rat model of autism. Prenatal zinc treatment prevented these autistic-like behaviors and striatal dopaminergic and mTOR disturbances in the offspring induced by LPS exposure. The present findings revealed a possible relation between maternal hypozincemia during gestation and the onset of autism. Furthermore, prenatal zinc administration appears to have a beneficial effect on the prevention of autism.

  1. Effects of mTOR and calcineurin inhibitors combined therapy in Epstein-Barr virus positive and negative Burkitt lymphoma cells.

    PubMed

    Wowro, Sylvia J; Schmitt, Katharina R L; Tong, Giang; Berger, Felix; Schubert, Stephan

    2016-01-01

    Post-transplant lymphoproliferative disorder is a severe complication in solid organ transplant recipients, which is highly associated with Epstein-Barr virus infection in pediatric patients and occasionally presents as Burkitt- or Burkitt-like lymphoma. The mammalian target of rapamycin (mTOR) pathway has been described as a possible antitumor target whose inhibition may influence lymphoma development and proliferation after pediatric transplantation. We treated Epstein-Barr virus positive (Raji and Daudi) and negative (Ramos) human Burkitt lymphoma derived cells with mTOR inhibitor everolimus alone and in combination with clinically relevant immunosuppressive calcineurin inhibitors (tacrolimus or cyclosporin A). Cell proliferation, toxicity, and mitochondrial metabolic activity were analyzed. The effect on mTOR Complex 1 downstream targets p70 S6 kinase, eukaryotic initiation factor 4G, and S6 ribosomal protein activation was also investigated. We observed that treatment with everolimus alone significantly decreased Burkitt lymphoma cell proliferation and mitochondrial metabolic activity. Everolimus in combination with cyclosporin A had a stronger suppressive effect in Epstein-Barr virus negative but not in Epstein-Barr virus positive cells. In contrast, tacrolimus completely abolished the everolimus-mediated suppressive effects. Moreover, we showed a significant decrease in activation of mTOR Complex 1 downstream targets after treatment with everolimus that was attenuated when combined with tacrolimus, but not with cyclosporin A. For the first time we showed the competitive effect between everolimus and tacrolimus when used as combination therapy on Burkitt lymphoma derived cells. Thus, according to our in vitro data, the combination of calcineurin inhibitor cyclosporin A with everolimus is preferred to the combination of tacrolimus and everolimus. PMID:26613512

  2. De novo mTOR inhibitor-based immunosuppression in ABO-incompatible kidney transplantation.

    PubMed

    Koch, Martina; Wiech, Thorsten; Marget, Matthias; Peine, Sven; Thude, Hansjörg; Achilles, Eike G; Fischer, Lutz; Lehnhardt, Anja; Thaiss, Friedrich; Nashan, Bjoern

    2015-11-01

    ABO-incompatible (ABOi) kidney transplantation (KTx) has become an accepted therapeutic option in renal replacement therapy for patients without a blood group-compatible living donor. Using different desensitization strategies, most centers apply B-cell depletion with rituximab and maintenance immunosuppression (IS) with tacrolimus and mycophenolic acid. This high load of total IS leads to an increased rate of surgical complications and virus infections in ABOi patients. Our aim was to establish ABOi KTx using an immunosuppressive regimen, which is effective in preventing acute rejection without increasing the risk for viral infections. Therefore, we selected a de novo immunosuppressive protocol with low-dose calcineurin inhibitor and the mTOR inhibitor everolimus for our ABOi program. Here, we report the first 25 patients with a complete three-yr follow-up treated with this regimen. Three-yr patient survival and graft survival were 96% and 83%. The rate of acute T-cell-mediated rejections was low (12%). Cytomegalovirus (CMV) infection was evident in one patient only (4%). Surgical complications were common (40%), but mild in 80% of cases. We demonstrate that ABOi KTx with a de novo mTOR inhibitor-based regimen is feasible without severe surgical or immunological complications and a low rate of viral infections.

  3. Everolimus enhances cellular cytotoxicity of lapatinib via the eukaryotic elongation factor-2 kinase pathway in nasopharyngeal carcinoma cells

    PubMed Central

    Liu, Lin; Wang, Zhi-Hui; Han, Jun; Tang, Con; Chen, Nan; Lin, Zhong; Peng, Pei-Jian

    2016-01-01

    Background Nasopharyngeal carcinoma (NPC) has a high relapse and metastatic rates; hence, development of new therapeutics is an immediate requirement. Lapatinib and everolimus have been demonstrated to be effective in the treatment of several carcinomas. This preclinical study aimed to investigate the effect and mechanism of lapatinib combined with everolimus on NPC cells. Methods The Cell Counting Kit 8 and colony formation assay were used to detect the effect of lapatinib alone or lapatinib combined with everolimus on the growth and proliferation of cells. Apoptosis was tested by flow cytometry and was further confirmed by western blot. The targets of lapatinib and the effects of lapatinib or everolimus on the eukaryotic elongation factor-2 (eEF-2) kinase pathway were analyzed by western blot, which also evaluated autophagy activity. Results Lapatinib inhibited the cellular viability and colony formation in NPC cells. At 24–72 h, the average half maximal inhibitory concentration (IC50) values of lapatinib were ranging from 3 to 5 μM. This study further found that lapatinib induced both apoptosis and autophagy in NPC cells, and this autophagic activity was described as type II programmed cell death via an eEF-2 kinase-dependent pathway. In addition, augmentation of lapatinib-induced autophagy by mammalian target of rapamycin (mTOR) inhibitor everolimus enhanced the cytocidal effect of lapatinib in NPC cells via the mTOR/S6 kinase/eEF-2 kinase pathway. Conclusion This study reveals that everolimus can sensitize NPC cells to lapatinib by the activation of eEF-2 kinase and provides a potential model of combination therapy. PMID:27785067

  4. Prevention of tumor growth driven by PIK3CA and HPV oncogenes by targeting mTOR signaling with metformin in oral squamous carcinomas expressing OCT3.

    PubMed

    Madera, Dmitri; Vitale-Cross, Lynn; Martin, Daniel; Schneider, Abraham; Molinolo, Alfredo A; Gangane, Nitin; Carey, Thomas E; McHugh, Jonathan B; Komarck, Christine M; Walline, Heather M; William, William N; Seethala, Raja R; Ferris, Robert L; Gutkind, J Silvio

    2015-03-01

    Most squamous cell carcinomas of the head and neck (HNSCC) exhibit a persistent activation of the PI3K-mTOR signaling pathway. We have recently shown that metformin, an oral antidiabetic drug that is also used to treat lipodystrophy in HIV-infected (HIV(+)) individuals, diminishes mTOR activity and prevents the progression of chemically induced experimental HNSCC premalignant lesions. Here, we explored the preclinical activity of metformin in HNSCCs harboring PIK3CA mutations and HPV oncogenes, both representing frequent HNSCC alterations, aimed at developing effective targeted preventive strategies. The biochemical and biologic effects of metformin were evaluated in representative HNSCC cells expressing mutated PIK3CA or HPV oncogenes (HPV(+)). The oral delivery of metformin was optimized to achieve clinical relevant blood levels. Molecular determinants of metformin sensitivity were also investigated, and their expression levels were examined in a large collection of HNSCC cases. We found that metformin inhibits mTOR signaling and tumor growth in HNSCC cells expressing mutated PIK3CA and HPV oncogenes, and that these activities require the expression of organic cation transporter 3 (OCT3/SLC22A3), a metformin uptake transporter. Coexpression of OCT3 and the mTOR pathway activation marker pS6 were observed in most HNSCC cases, including those arising in HIV(+) patients. Activation of the PI3K-mTOR pathway is a widespread event in HNSCC, including HPV(-) and HPV(+) lesions arising in HIV(+) patients, all of which coexpress OCT3. These observations may provide a rationale for the clinical evaluation of metformin to halt HNSCC development from precancerous lesions, including in HIV(+) individuals at risk of developing HPV(-) associated cancers.

  5. Prevention of tumor growth driven by PIK3CA and HPV oncogenes by targeting mTOR signaling with metformin in oral squamous carcinomas expressing OCT3

    PubMed Central

    Madera, Dmitri; Vitale-Cross, Lynn; Martin, Daniel; Schneider, Abraham; Molinolo, Alfredo A.; Gangane, Nitin; Carey, Thomas E.; McHugh, Jonathan B.; Komarck, Christine M.; Walline, Heather M.; William, William N.; Seethala, Raja R.; Ferris, Robert; Gutkind, J. Silvio

    2015-01-01

    Most head and neck squamous cell carcinomas (HNSCC) exhibit a persistent activation of the PI3K-mTOR signaling pathway. We have recently shown that metformin, an oral antidiabetic drug that is also used to treat lipodystrophy in HIV-infected (HIV+) individuals, diminishes mTOR activity and prevents the progression of chemically-induced experimental HNSCC premalignant lesions. Here, we explored the preclinical activity of metformin in HNSCCs harboring PIK3CA mutations and HPV oncogenes, both representing frequent HNSCC alterations, aimed at developing effective targeted preventive strategies. The biochemical and biological effects of metformin were evaluated in representative HNSCC cells expressing mutated PIK3CA or HPV oncogenes (HPV+). The oral delivery of metformin was optimized to achieve clinical relevant blood levels. Molecular determinants of metformin sensitivity were also investigated, and their expression levels examined in a large collection of HNSCC cases. We found that metformin inhibits mTOR signaling and tumor growth in HNSCC cells expressing mutated PIK3CA and HPV oncogenes, and that these activities require the expression of organic cation transporter 3 (OCT3/SLC22A3), a metformin uptake transporter. Co-expression of OCT3 and the mTOR pathway activation marker pS6 were observed in most HNSCC cases, including those arising in HIV+ patients. Activation of the PI3K-mTOR pathway is a widespread event in HNSCC, including HPV− and HPV+ lesions arising in HIV+ patients, all of which co-express OCT3. These observations may provide a rationale for the clinical evaluation of metformin to halt HNSCC development from precancerous lesions, including in HIV+ individuals at risk of developing HPV-associated cancers. PMID:25681087

  6. Role of mTOR Inhibitors in Kidney Disease

    PubMed Central

    Kajiwara, Moto; Masuda, Satohiro

    2016-01-01

    The first compound that inhibited the mammalian target of rapamycin (mTOR), sirolimus (rapamycin) was discovered in the 1970s as a soil bacterium metabolite collected on Easter Island (Rapa Nui). Because sirolimus showed antiproliferative activity, researchers investigated its molecular target and identified the TOR1 and TOR2. The mTOR consists of mTOR complex 1 (mTORC1) and mTORC2. Rapalogues including sirolimus, everolimus, and temsirolimus exert their effect mainly on mTORC1, whereas their inhibitory effect on mTORC2 is mild. To obtain compounds with more potent antiproliferative effects, ATP-competitive inhibitors of mTOR targeting both mTORC1 and mTORC2 have been developed and tested in clinical trials as anticancer drugs. Currently, mTOR inhibitors are used as anticancer drugs against several solid tumors, and immunosuppressive agents for transplantation of various organs. This review discusses the role of mTOR inhibitors in renal disease with a particular focus on renal cancer, diabetic nephropathy, and kidney transplantation. PMID:27338360

  7. mTOR and regulation of energy homeostasis in humans.

    PubMed

    Mannaa, Marwan; Krämer, Stephanie; Boschmann, Michael; Gollasch, Maik

    2013-10-01

    Patients treated with the mammalian or mechanistic target of rapamycin (mTOR) inhibitor everolimus in order to slow progression of autosomal-dominant polycystic kidney disease (ADPKD) showed a significant reduction of body weight. Although the detailed mechanism of how mTOR inhibition interferes with body weight regulation is rather unclear, present data suggest that this effect is mediated by both central and peripheral mechanisms. These findings in ADPKD patients are in contrast to well-documented effects of hypothalamic mTOR on regulation of energy homeostasis and eating behavior in rodents. In a number of rodent models, the mTOR inhibitor rapamycin induces increased food intake, which is accompanied by increased body weight. However, animal data are inconsistent. This review highlights some of the regulatory signals and key mechanisms that are important for balancing energy intake and energy expenditure with a special focus on adipose tissue-derived adipokines and their interaction with mTOR regarding local regulation of tissue perfusion and metabolism and overall systemic energy homeostasis. Specifically, clinical aspects of an impaired mTOR signaling pathway regarding the development of obesity and type-2 diabetes mellitus will be discussed. PMID:23756767

  8. Therapeutic potential and adverse events of everolimus for treatment of hepatocellular carcinoma - systematic review and meta-analysis.

    PubMed

    Yamanaka, Kenya; Petrulionis, Marius; Lin, Shibo; Gao, Chao; Galli, Uwe; Richter, Susanne; Winkler, Susanne; Houben, Philipp; Schultze, Daniel; Hatano, Etsuro; Schemmer, Peter

    2013-12-01

    Everolimus is an orally administrated mammalian target of rapamycin (mTOR) inhibitor. Several large-scale randomized controlled trials (RCTs) have demonstrated the survival benefits of everolimus at the dose of 10 mg/day for solid cancers. Furthermore, mTOR-inhibitor-based immunosuppression is associated with survival benefits for patients with hepatocellular carcinoma (HCC) who have received liver transplantation. However, a low rate of tumor reduction and some adverse events have been pointed out. This review summarizes the antitumor effects and adverse events of everolimus and evaluates its possible application in advanced HCC. For the meta-analysis of adverse events, we used the RCTs for solid cancers. The odds ratios of adverse events were calculated using the Peto method. Manypreclinical studies demonstrated that everolimus had antitumor effects such as antiproliferation and antiangiogenesis. However, some differences in the effects were observed among in vivo animal studies for HCC treatment. Meanwhile, clinical studies demonstrated that the response rate of single-agent everolimus was low, though survival benefits could be expected. The meta-analysis revealed the odds ratios (95% confidence interval [CI]) of stomatitis: 5.42 [4.31-6.73], hyperglycemia: 3.22 [2.37-4.39], anemia: 3.34 [2.37-4.67], pneumonitis: 6.02 [3.95-9.16], aspartate aminotransferase levels: 2.22 [1.37-3.62], and serum alanine aminotransferase levels: 2.94 [1.72-5.02], respectively. Everolimus at the dose of 10 mg/day significantly increased the risk of the adverse events. In order to enable its application to the standard conventional therapies of HCC, further studies are required to enhance the antitumor effects and manage the adverse events of everolimus. PMID:24403259

  9. Effects of vatalanib on tumor growth can be potentiated by mTOR blockade in vivo.

    PubMed

    Jaeger-Lansky, Agnes; Cejka, Daniel; Ying, Liu; Preusser, Matthias; Hoeflmayer, Doris; Fuereder, Thorsten; Koehrer, Stefan; Wacheck, Volker

    2010-06-01

    The vascular endothelial growth factor (VEGF) is a central mediator of tumor-induced angiogenesis. Everolimus, a mammalian target of rapamycin (mTOR) inhibitor, decreases VEGF-secretion of cancer cells. Vatalanib is a selective inhibitor of VEGF receptors 1-3. In the present study it was hypothesized that dual inhibition of VEGF signaling by inhibition of VEGF production and VEGF receptor signaling leads to synergistic anti-tumor effects. In vitro, effects of vatalanib and everolimus on cell proliferation, cell cycle, apoptosis and signal transduction were examined in three gastric cancer cell lines. Effects on angiogenesis were assessed using tube formation assays of cultured human umbilical vein endothelial cells (HUVECs). In vivo, the antitumor effect of compounds was studied using a gastric cancer xenograft nude mouse model. VEGF of murine origin (mVEGF) and human cancer cell-derived VEGF (hVEGF) were studied separately by specific ELISAs. Tumor vascularization and proliferation were quantified by immunohistochemistry. In vitro, everolimus but not vatalanib decreased gastric cancer proliferation without inducing apoptosis. Vatalanib abolished endothelial cell tube formation, whereas inhibition of tube formation by everolimus was incomplete. In vivo, the combination of vatalanib with everolimus was superior to single agent treatments and reduced tumor size by about 50% relative to everolimus monotherapy (p < 0.005). Pharmacodynamic analysis of VEGF plasma level showed a decrease of hVEGF by everolimus and indicated a trend towards lower mVEGF level only in the combination group. In line, there was a tendency for lower vascular density and proliferation for combination treatment. We conclude that in a preclinical model of gastric cancer the antitumor activity of vatalanib can be augmented by everolimus. PMID:20404549

  10. Long-Term Use of Everolimus in Patients with Tuberous Sclerosis Complex: Final Results from the EXIST-1 Study

    PubMed Central

    Franz, David N.; Belousova, Elena; Sparagana, Steven; Bebin, E. Martina; Frost, Michael D.; Kuperman, Rachel; Witt, Olaf; Kohrman, Michael H.; Flamini, J. Robert; Wu, Joyce Y.; Curatolo, Paolo; de Vries, Petrus J.; Berkowitz, Noah; Niolat, Julie; Jóźwiak, Sergiusz

    2016-01-01

    Background Everolimus, a mammalian target of rapamycin (mTOR) inhibitor, has demonstrated efficacy in treating subependymal giant cell astrocytomas (SEGAs) and other manifestations of tuberous sclerosis complex (TSC). However, long-term use of mTOR inhibitors might be necessary. This analysis explored long-term efficacy and safety of everolimus from the conclusion of the EXIST-1 study (NCT00789828). Methods and Findings EXIST-1 was an international, prospective, double-blind, placebo-controlled phase 3 trial examining everolimus in patients with new or growing TSC-related SEGA. After a double-blind core phase, all remaining patients could receive everolimus in a long-term, open-label extension. Everolimus was initiated at a dose (4.5 mg/m2/day) titrated to a target blood trough of 5–15 ng/mL. SEGA response rate (primary end point) was defined as the proportion of patients achieving confirmed ≥50% reduction in the sum volume of target SEGA lesions from baseline in the absence of worsening nontarget SEGA lesions, new target SEGA lesions, and new or worsening hydrocephalus. Of 111 patients (median age, 9.5 years) who received ≥1 dose of everolimus (median duration, 47.1 months), 57.7% (95% confidence interval [CI], 47.9–67.0) achieved SEGA response. Of 41 patients with target renal angiomyolipomas at baseline, 30 (73.2%) achieved renal angiomyolipoma response. In 105 patients with ≥1 skin lesion at baseline, skin lesion response rate was 58.1%. Incidence of adverse events (AEs) was comparable with that of previous reports, and occurrence of emergent AEs generally decreased over time. The most common AEs (≥30% incidence) suspected to be treatment-related were stomatitis (43.2%) and mouth ulceration (32.4%). Conclusions Everolimus use led to sustained reduction in tumor volume, and new responses were observed for SEGA and renal angiomyolipoma from the blinded core phase of the study. These findings support the hypothesis that everolimus can safely reverse

  11. Targeting of tumor endothelial cells combining 2 Gy/day of X-ray with Everolimus is the effective modality for overcoming clinically relevant radioresistant tumors

    PubMed Central

    Kuwahara, Yoshikazu; Mori, Miyuki; Kitahara, Shuji; Fukumoto, Motoi; Ezaki, Taichi; Mori, Shiro; Echigo, Seishi; Ohkubo, Yasuhito; Fukumoto, Manabu

    2014-01-01

    Radiotherapy is widely used to treat cancer because it has the advantage of physically and functionally conserving the affected organ. To improve radiotherapy and investigate the molecular mechanisms of cellular radioresistance, we established a clinically relevant radioresistant (CRR) cell line, SAS-R, from SAS cells. SAS-R cells continue to proliferate when exposed to fractionated radiation (FR) of 2 Gy/day for more than 30 days in vitro. A xenograft tumor model of SAS-R was also resistant to 2 Gy/day of X-rays for 30 days. The density of blood vessels in SAS-R tumors was higher than in SAS tumors. Everolimus, a mammalian target of rapamycin (mTOR) inhibitor, sensitized microvascular endothelial cells to radiation, but failed to radiosensitize SAS and SAS-R cells in vitro. Everolimus with FR markedly reduced SAS and SAS-R tumor volumes. Additionally, the apoptosis of endothelial cells (ECs) increased in SAS-R tumor tissues when both Everolimus and radiation were administered. Both CD34-positive and tomato lectin-positive blood vessel densities in SAS-R tumor tissues decreased remarkably after the Everolimus and radiation treatment. Everolimus-induced apoptosis of vascular ECs in response to radiation was also followed by thrombus formation that leads to tumor necrosis. We conclude that FR combined with Everolimus may be an effective modality to overcome radioresistant tumors via targeting tumor ECs. PMID:24464839

  12. Targeting of tumor endothelial cells combining 2 Gy/day of X-ray with Everolimus is the effective modality for overcoming clinically relevant radioresistant tumors.

    PubMed

    Kuwahara, Yoshikazu; Mori, Miyuki; Kitahara, Shuji; Fukumoto, Motoi; Ezaki, Taichi; Mori, Shiro; Echigo, Seishi; Ohkubo, Yasuhito; Fukumoto, Manabu

    2014-04-01

    Radiotherapy is widely used to treat cancer because it has the advantage of physically and functionally conserving the affected organ. To improve radiotherapy and investigate the molecular mechanisms of cellular radioresistance, we established a clinically relevant radioresistant (CRR) cell line, SAS-R, from SAS cells. SAS-R cells continue to proliferate when exposed to fractionated radiation (FR) of 2 Gy/day for more than 30 days in vitro. A xenograft tumor model of SAS-R was also resistant to 2 Gy/day of X-rays for 30 days. The density of blood vessels in SAS-R tumors was higher than in SAS tumors. Everolimus, a mammalian target of rapamycin (mTOR) inhibitor, sensitized microvascular endothelial cells to radiation, but failed to radiosensitize SAS and SAS-R cells in vitro. Everolimus with FR markedly reduced SAS and SAS-R tumor volumes. Additionally, the apoptosis of endothelial cells (ECs) increased in SAS-R tumor tissues when both Everolimus and radiation were administered. Both CD34-positive and tomato lectin-positive blood vessel densities in SAS-R tumor tissues decreased remarkably after the Everolimus and radiation treatment. Everolimus-induced apoptosis of vascular ECs in response to radiation was also followed by thrombus formation that leads to tumor necrosis. We conclude that FR combined with Everolimus may be an effective modality to overcome radioresistant tumors via targeting tumor ECs. PMID:24464839

  13. RAD001 (everolimus) inhibits tumour growth in xenograft models of human hepatocellular carcinoma.

    PubMed

    Huynh, Hung; Chow, K H Pierce; Soo, Khee Chee; Toh, Han Chong; Choo, Su Pin; Foo, Kian Fong; Poon, Donald; Ngo, Van Chanh; Tran, Evelyn

    2009-07-01

    Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide and highly resistant to available chemotherapies. Mammalian target of rapamycin (mTOR) functions to regulate protein translation, angiogenesis and cell cycle progression in many cancers including HCC. In the present study, subcutaneous patient-derived HCC xenografts were used to study the effects of an mTOR inhibitor, RAD001 (everolimus), on tumour growth, apoptosis and angiogenesis. We report that oral administration of RAD001 to mice bearing patient-derived HCC xenografts resulted in a dose-dependent inhibition of tumour growth. RAD001-induced growth suppression was associated with inactivation of downstream targets of mTOR, reduction in VEGF expression and microvessel density, inhibition of cell proliferation, up-regulation of p27(Kip1) and down-regulation of p21(Cip1/Waf1), Cdk-6, Cdk-2, Cdk-4, cdc-25C, cyclin B1 and c-Myc. Our data indicate that the mTOR pathway plays an important role in angiogenesis, cell cycle progression and proliferation of liver cancer cells. Our study provides a strong rationale for clinical investigation of mTOR inhibitor RAD001 in patients with HCC.

  14. Long-term mTOR inhibitors administration evokes altered calcium homeostasis and platelet dysfunction in kidney transplant patients

    PubMed Central

    López, Esther; Berna-Erro, Alejandro; Bermejo, Nuria; Brull, José María; Martinez, Rocío; Garcia Pino, Guadalupe; Alvarado, Raul; Salido, Ginés María; Rosado, Juan Antonio; Cubero, Juan José; Redondo, Pedro Cosme

    2013-01-01

    The use of the mammal target of rapamycin (mTOR) inhibitors has been consolidated as the therapy of election for preventing graft rejection in kidney transplant patients, despite their immunosuppressive activity is less strong than anti-calcineurin agents like tacrolimus and cyclosporine A. Furthermore, as mTOR is widely expressed, rapamycin (a macrolide antibiotic produced by Streptomyces hygroscopicus) is recommended in patients presenting neoplasia due to its antiproliferative actions. Hence, we have investigated whether rapamycin presents side effects in the physiology of other cell types different from leucocytes, such as platelets. Blood samples were drawn from healthy volunteers and kidney transplant patients long-term medicated with rapamycin: sirolimus and everolimus. Platelets were either loaded with fura-2 or directly stimulated, and immunoassayed or fixed with Laemmli's buffer to perform the subsequent analysis of platelet physiology. Our results indicate that rapamycin evokes a biphasic time-dependent alteration in calcium homeostasis and function in platelets from kidney transplant patients under rapamycin regime, as demonstrated by the reduction in granule secretion observed and subsequent impairment of platelet aggregation in these patients compared with healthy volunteers. Platelet count was also reduced in these patients, thus 41% of patients presented thrombocytopenia. All together our results show that long-term administration of rapamycin to kidney transplant patients evokes alteration in platelet function. PMID:23577651

  15. The mTORC1 inhibitor everolimus has antitumor activity in vitro and produces tumor responses in patients with relapsed T-cell lymphoma

    PubMed Central

    Witzig, Thomas E.; Reeder, Craig; Han, Jing Jing; LaPlant, Betsy; Stenson, Mary; Tun, Han W.; Macon, William; Ansell, Stephen M.; Habermann, Thomas M.; Inwards, David J.; Micallef, Ivana N.; Johnston, Patrick B.; Porrata, Luis F.; Colgan, Joseph P.; Markovic, Svetomir; Nowakowski, Grzegorz S.

    2015-01-01

    Everolimus is an oral agent that targets the mammalian target of rapamycin (mTOR) pathway. This study investigated mTOR pathway activation in T-cell lymphoma (TCL) cell lines and assessed antitumor activity in patients with relapsed/refractory TCL in a phase 2 trial. The mTOR pathway was activated in all 6 TCL cell lines tested and everolimus strongly inhibited malignant T-cell proliferation with minimal cytotoxic effects. Everolimus completely inhibited phosphorylation of ribosomal S6, a raptor/mTOR complex 1 (mTORC1) target, without a compensatory activation of the rictor/mTORC2 target Akt (S475). In the clinical trial, 16 patients with relapsed TCL were enrolled and received everolimus 10 mg by mouth daily. Seven patients (44%) had cutaneous (all mycosis fungoides); 4 (25%) had peripheral T cell not otherwise specified; 2 (13%) had anaplastic large cell; and 1 each had extranodal natural killer/T cell, angioimmunoblastic, and precursor T-lymphoblastic leukemia/lymphoma types. The overall response rate was 44% (7/16; 95% confidence interval [CI]: 20% to 70%). The median progression-free survival was 4.1 months (95% CI, 1.5-6.5) and the median overall survival was 10.2 months (95% CI, 2.6-44.3). The median duration of response for the 7 responders was 8.5 months (95% CI, 1.0 to not reached). These studies indicate that everolimus has antitumor activity and provide proof-of-concept that targeting the mTORC1 pathway in TCL is clinically relevant. This trial was registered at www.clinicaltrials.gov as #NCT00436618. PMID:25921059

  16. Adjuvant Everolimus for Resected Kidney Cancer

    Cancer.gov

    In this clinical trial, patients with renal cell cancer who have undergone partial or complete nephrectomy will be randomly assigned to take everolimus tablets or matching placebo tablets daily for 54 weeks.

  17. Molecular analysis of a male breast cancer patient with prolonged stable disease under mTOR/PI3K inhibitors BEZ235/everolimus

    PubMed Central

    Brannon, A. Rose; Frizziero, Melissa; Chen, David; Hummel, Jennifer; Gallo, Jorge; Riester, Markus; Patel, Parul; Cheung, Wing; Morrissey, Michael; Carbone, Carmine; Cottini, Silvia; Tortora, Giampaolo; Melisi, Davide

    2016-01-01

    The mTORC1 inhibitor everolimus (Afinitor/RAD001) has been approved for multiple cancer indications, including ER+/HER2− metastatic breast cancer. However, the combination of everolimus with the dual PI3K/mTOR inhibitor BEZ235 was shown to be more efficacious than either everolimus or BEZ235 alone in preclinical models. Herein, we describe a male breast cancer (MBC) patient who was diagnosed with hormone receptor-positive (HR+)/HER2− stage IIIA invasive ductal carcinoma and sequentially treated with chemoradiotherapy and hormonal therapy. Upon the development of metastases, the patient began a 200 mg twice-daily BEZ235 and 2.5 mg weekly everolimus combination regimen. The patient sustained a prolonged stable disease of 18 mo while undergoing the therapy, before his tumor progressed again. Therefore, we sought to both better understand MBC and investigate the underlying molecular mechanisms of the patient's sensitivity and subsequent resistance to the BEZ235/everolimus combination therapy. Genomic and immunohistochemical analyses were performed on samples collected from the initial invasive ductal carcinoma pretreatment and a metastasis postprogression on the BEZ235/everolimus combination treatment. Both tumors were relatively quiet genomically with no overlap to recurrent MBC alterations in the literature. Markers of PI3K/mTOR pathway hyperactivation were not identified in the pretreatment sample, which complements previous reports of HR+ female breast cancers being responsive to mTOR inhibition without this activation. The postprogression sample, however, demonstrated greater than fivefold increased estrogen receptor and pathogenesis-related protein expression, which could have constrained the PI3K/mTOR pathway inhibition by BEZ235/everolimus. Overall, these analyses have augmented the limited episteme on MBC genetics and treatment. PMID:27148582

  18. Molecular analysis of a male breast cancer patient with prolonged stable disease under mTOR/PI3K inhibitors BEZ235/everolimus.

    PubMed

    Brannon, A Rose; Frizziero, Melissa; Chen, David; Hummel, Jennifer; Gallo, Jorge; Riester, Markus; Patel, Parul; Cheung, Wing; Morrissey, Michael; Carbone, Carmine; Cottini, Silvia; Tortora, Giampaolo; Melisi, Davide

    2016-03-01

    The mTORC1 inhibitor everolimus (Afinitor/RAD001) has been approved for multiple cancer indications, including ER(+)/HER2(-) metastatic breast cancer. However, the combination of everolimus with the dual PI3K/mTOR inhibitor BEZ235 was shown to be more efficacious than either everolimus or BEZ235 alone in preclinical models. Herein, we describe a male breast cancer (MBC) patient who was diagnosed with hormone receptor-positive (HR(+))/HER2(-) stage IIIA invasive ductal carcinoma and sequentially treated with chemoradiotherapy and hormonal therapy. Upon the development of metastases, the patient began a 200 mg twice-daily BEZ235 and 2.5 mg weekly everolimus combination regimen. The patient sustained a prolonged stable disease of 18 mo while undergoing the therapy, before his tumor progressed again. Therefore, we sought to both better understand MBC and investigate the underlying molecular mechanisms of the patient's sensitivity and subsequent resistance to the BEZ235/everolimus combination therapy. Genomic and immunohistochemical analyses were performed on samples collected from the initial invasive ductal carcinoma pretreatment and a metastasis postprogression on the BEZ235/everolimus combination treatment. Both tumors were relatively quiet genomically with no overlap to recurrent MBC alterations in the literature. Markers of PI3K/mTOR pathway hyperactivation were not identified in the pretreatment sample, which complements previous reports of HR(+) female breast cancers being responsive to mTOR inhibition without this activation. The postprogression sample, however, demonstrated greater than fivefold increased estrogen receptor and pathogenesis-related protein expression, which could have constrained the PI3K/mTOR pathway inhibition by BEZ235/everolimus. Overall, these analyses have augmented the limited episteme on MBC genetics and treatment.

  19. The Role of mTOR Inhibitors in the Treatment of Patients with Tuberous Sclerosis Complex: Evidence-based and Expert Opinions.

    PubMed

    Curatolo, Paolo; Bjørnvold, Marit; Dill, Patricia E; Ferreira, José Carlos; Feucht, Martha; Hertzberg, Christoph; Jansen, Anna; Jóźwiak, Sergiusz; Kingswood, J Christopher; Kotulska, Katarzyna; Macaya, Alfons; Moavero, Romina; Nabbout, Rima; Zonnenberg, Bernard A

    2016-04-01

    Tuberous sclerosis complex (TSC) is a genetic disorder arising from mutations in the TSC1 or TSC2 genes. The resulting over-activation of the mammalian target of rapamycin (mTOR) signalling pathway leaves patients with TSC susceptible to the growth of non-malignant tumours in multiple organs. Previously, surgery was the main therapeutic option for TSC. However, pharmacological therapy with mTOR inhibitors such as everolimus and sirolimus is now emerging as an alternate approach. Everolimus and sirolimus have already been shown to be effective in treating subependymal giant cell astrocytoma (SEGA) and renal angiomyolipoma (AML), and everolimus is currently being evaluated in treating TSC-related epilepsy. In November 2013 a group of European experts convened to discuss the current options and practical considerations for treating various manifestations of TSC. This article provides evidence-based recommendations for the treatment of SEGA, TSC-related epilepsy and renal AML, with a focus on where mTOR inhibitor therapy may be considered alongside other treatment options. Safety considerations regarding mTOR inhibitor therapy are also reviewed. With evidence of beneficial effects in neurological and non-neurological TSC manifestations, mTOR inhibitors may represent a systemic treatment for TSC. PMID:26927950

  20. A single arm phase 1b study of everolimus and sunitinib in patients with advanced renal cell carcinoma (RCC)

    PubMed Central

    Kanesvaran, R.; Watt, K.; Turnbull, J. D.; Armstrong, A. J.; Cohen-Wolkowiez, M.; George, D. J.

    2016-01-01

    Background Everolimus ,an oral inhibitor of mammalian target of rapamycin (mTOR), and sunitinib, an oral inhibitor of VEGF/PDGF receptor tyrosine kinase signaling, have both been shown to provide clinical benefit in patients with advanced RCC. We sought to determine the safety and efficacy of combination therapy with these agents in patients with advanced RCC. Methods We conducted a phase Ib dose escalation trial of sunitinib and everolimus in patients with advanced metastatic RCC. Prior nephrectomy was required, and prior radiation or chemotherapy other than VEGF/mTOR-based therapies was permitted. The primary endpoint was to determine the MTD/recommended phase 2 dose. Results A total of 4 out of a planned 30 subjects were enrolled in this study (M:F= 2:2; mean age 52 years, 50% with KPS <80). The first three patients were enrolled on a 4+2 dosing schedule of daily sunitinib 50 mg and weekly everolimus 30 mg. Mean time on drug was 99 days. One partial response was seen. Toxicities included mucositis, thrombocytopenia, anemia, fatigue, dehydration and hypoglycemia. Due to multiple grade 3–4 toxicities, the protocol was amended to 2+1 dosing of sunitinib 37.5 mg and daily everolimus 5mg. The first patient on this schedule died from multi-organ failure with septic shock after 1 cycle of treatment. Subsequently, the study was closed. Pharmacokinetics results inconclusively suggest that toxicities could be attributed to the drug exposure. Conclusions Combined use of everolimus and sunitinib in the treatment of mRCC was not well tolerated in this small cohort. PMID:26174223

  1. Peroxisome proliferator-activated receptor δ (PPARδ) induces estrogen receptor-positive mammary neoplasia through an inflammatory and metabolic phenotype linked to mTor activation

    PubMed Central

    Yuan, Hongyan; Lu, Jin; Xiao, Junfeng; Upadhyay, Geeta; Umans, Rachel; Kallakury, Bhaskar; Yin, Yuhzi; Fant, Michael E.; Kopelovich, Levy; Glazer, Robert I.

    2013-01-01

    The peroxisome proliferator-activated receptor-δ (PPARδ) regulates a multitude of physiological processes associated with glucose and lipid metabolism, inflammation and proliferation. One or more of these processes are potential risk factors for the ability of PPARδ agonists to promote tumorigenesis in the mammary gland. In the present study, we describe a new transgenic mouse model in which activation of PPARδ in the mammary epithelium by endogenous or synthetic ligands resulted in progressive histopathological changes that culminated in the appearance of estrogen receptor- and progesterone receptor-positive and ErbB2-negative infiltrating ductal carcinomas. Multiparous mice presented with mammary carcinomas after a latency of 12 months, and administration of the PPARδ ligand GW501516 reduced tumor latency to five months. Histopathological changes occurred concurrently with an increase in an inflammatory, invasive, metabolic and proliferative gene signature, including expression of the trophoblast gene, Plac1, beginning one week after GW501516 treatment, and remained elevated throughout tumorigenesis. The appearance of malignant changes correlated with a pronounced increase in phosphatidylcholine and lysophosphatidic acid metabolites, which coincided with activation of Akt and mTor signaling that were attenuated by treatment with the mTor inhibitor everolimus. Our findings are the first to demonstrate a direct role of PPARδ in the pathogenesis of mammary tumorigenesis, and suggest a rationale for therapeutic approaches to prevent and treat this disease. PMID:23811944

  2. mTOR Inhibitors and Their Potential Role in Therapy in Leukemia and Other Haematologic Malignancies

    PubMed Central

    Teachey, David T.; Grupp, Stephan A.; Brown, Valerie I.

    2009-01-01

    Summary The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that functions as a key regulator of cell growth, protein synthesis, and cell-cycle progression through interactions with a number of signaling pathways, including PI3K/AKT, ras, TCL1, and BCR/ABL. Many haematologic malignancies have aberrant activation of the mTOR and related signaling pathways. Accordingly, mTOR inhibitors, a class of signal transduction inhibitors that were originally developed as immunosuppressive agents, are being investigated in preclinical models and clinical trials for a number of haematologic malignancies. Sirolimus and second generation mTOR inhibitors such as temsirolimus and everolimus, are safe and relatively well-tolerated, making them potentially attractive as single agents or in combination with conventional cytotoxics and other targeted therapies. Promising early clinical data suggests activity of mTOR inhibitors in a number of haematologic diseases, including acute lymphoblastic leukemia, chronic myelogenous leukemia, mantle cell lymphoma, anaplastic large cell lymphoma, and lymphoproliferative disorders. This review describes the rationale for using mTOR inhibitors in a variety of haematologic diseases with a focus on their use in leukemia. PMID:19344392

  3. Novel agents and associated toxicities of inhibitors of the pi3k/Akt/mtor pathway for the treatment of breast cancer

    PubMed Central

    Chia, S.; Gandhi, S.; Joy, A.A.; Edwards, S.; Gorr, M.; Hopkins, S.; Kondejewski, J.; Ayoub, J.P.; Califaretti, N.; Rayson, D.; Dent, S.F.

    2015-01-01

    The pi3k/Akt/mtor (phosphatidylinositol 3 kinase/ Akt/mammalian target of rapamycin) signalling pathway is an established driver of oncogenic activity in human malignancies. Therapeutic targeting of this pathway holds significant promise as a treatment strategy. Everolimus, an mtor inhibitor, is the first of this class of agents approved for the treatment of hormone receptor–positive, human epidermal growth factor receptor 2–negative advanced breast cancer. Everolimus has been associated with significant improvements in progression-free survival; however, it is also associated with increased toxicity related to its specific mechanism of action. Methods A comprehensive review of the literature conducted using a focused medline search was combined with a search of current trials at http://ClinicalTrials.gov/. Summary tables of the toxicities of the various classes of pi3k/Akt/mtor inhibitors were created. A broad group of Canadian health care professionals was assembled to review the data and to produce expert opinion and summary recommendations for possible best practices in managing the adverse events associated with these pathway inhibitors. Results Differing toxicities are associated with the various classes of pi3k/Akt/mtor pathway inhibitors. The most common unique adverse events observed in everolimus clinical trials in breast cancer include stomatitis (all grades: approximately 60%), noninfectious pneumonitis (15%), rash (40%), hyperglycemia (15%), and immunosuppression (40%). To minimize grades 3 and 4 toxicities and to attempt to attain optimal outcomes, effective management of those adverse events is critical. Management should be interdisciplinary and should use approaches that include education, early recognition, active intervention, and potentially prophylactic strategies. Discussion Everolimus likely represents the first of many complex oral targeted therapies for the treatment of breast cancer. Using this agent as a template, it is essential to

  4. Everolimus and intensive behavioral therapy in an adolescent with tuberous sclerosis complex and severe behavior☆☆☆★

    PubMed Central

    Gipson, Tanjala T.; Jennett, Heather; Wachtel, Lee; Gregory, Mary; Poretti, Andrea; Johnston, Michael V.

    2013-01-01

    Background Self-injury and aggression have been reported in individuals with TSC (tuberous sclerosis complex), yet few data exist about treatment. Everolimus, an mTOR inhibitor, has been FDA-approved for subependymal giant cell astrocytomas (SEGAs) and renal angiomyolipomas in TSC. However, clinical use of everolimus with direct, real-time observations of self-injury and aggression in an individual with TSC has not been reported. Methods During an inpatient admission to a neurobehavioral unit, real-time measurements of behaviors and seizures were recorded. An interdisciplinary team used these data to make treatment decisions and applied behavioral and pharmacological treatments, one at a time, in order to evaluate their effects. Results Aggression and self-injury improved with applied behavioral analysis (ABA), lithium, and asenapine. Improvements in SEGA size, facial angiofibromas, seizures, and the most stable low rates of self-injury were observed during the interval of treatment with everolimus. Conclusion Mechanism-based treatments in the setting of an evidence-based behavioral and psychopharmacological intervention program may be a model with utility for characterization and treatment of individuals with severe behavior and TSC. PMID:25667844

  5. [Response to everolimus in patients with giant cell astrocytoma associated to tuberous sclerosis complex].

    PubMed

    Mateos-González, M Elena; López-Laso, Eduardo; Vicente-Rueda, Josefina; Camino-León, Rafael; Fernández-Ramos, Joaquín A; Baena-Gómez, M Auxiliadora; Peña-Rosa, M José

    2014-12-01

    Introduccion. Los astrocitomas subependimarios de celulas gigantes (SEGA) se presentan en el 5-20% de los pacientes con complejo esclerosis tuberosa (CET) y son los tumores cerebrales mas comunes en el CET. Son tumores benignos, de estirpe glioneural, que se desarrollan fundamentalmente en las primeras dos decadas de la vida, en general cercanos al foramen de Monro, y pueden ocasionar hidrocefalia e hipertension intracraneal. Constituyen la principal causa de muerte en el CET. Recientemente, los inhibidores mTOR han demostrado ser una alternativa terapeutica a la reseccion quirurgica. Objetivo. Describir nuestra experiencia con everolimus para el tratamiento de pacientes con SEGA y CET. Pacientes y metodos. Estudio prospectivo de la respuesta de los pacientes con CET y al menos un SEGA en crecimiento. Resultados. Recibieron tratamiento tres mujeres y tres varones con una edad media de 12,3 años. Un paciente habia sido previamente intervenido quirurgicamente por SEGA con hidrocefalia. El diametro maximo medio del SEGA al inicio del tratamiento era de 15,3 mm (rango: 11,3-24,8 mm). Se inicio tratamiento con everolimus, 2,5 mg/dia por via oral en pacientes con superficie corporal < 1,2 m2 y 5 mg/dia en pacientes con superficie corporal > 1,2 m2. Dos pacientes presentaron hipertrigliceridemia; uno, anorexia; otro, un afta; y una paciente, amenorrea. La reduccion media del volumen del SEGA a los tres meses de tratamiento fue del 46%, y la reduccion se mantuvo estable en controles posteriores (6-25 meses). Conclusiones. El tratamiento con everolimus disminuye el tamaño de los SEGA asociados a CET con un perfil de seguridad adecuado, y constituye una alternativa a la cirugia en casos seleccionados.

  6. Phase I study of panobinostat plus everolimus in patients with relapsed or refractory lymphoma

    PubMed Central

    Oki, Yasuhiro; Buglio, Daniela; Fanale, Michelle; Fayad, Luis; Copeland, Amanda; Romaguera, Jorge; Kwak, Larry W.; Pro, Barbara; de Castro Faria, Silvana; Neelapu, Sattva; Fowler, Nathan; Hagemeister, Fredrick; Zhang, Jiexin; Zhou, Shouhao; Feng, Lei; Younes, Anas

    2015-01-01

    Purpose To evaluate the safety and efficacy of panobinostat plus everolimus in patients with relapsed Hodgkin and non-Hodgkin lymphoma. The concept was supported by the single agent clinical activity of histone deacetylase inhibitors and mTOR inhibitors, and on the in vitro mechanism-based synergistic antiproliferative activity. Experimental Design This was a phase I study in patients with relapsed or refractory Hodgkin and non-Hodgkin lymphoma using panobinostat orally on Monday/Wednesday/Friday and everolimus orally daily. Toxicity and responses were assessed in dose escalation cohort followed by expansion cohort at maximum tolerated dose. Exploratory analysis of serum cytokine levels were performed. Results Thirty patients were enrolled onto four dose levels The dose limiting toxicity was thrombocytopenia. The maximal tolerated dose was panobinostat 20 mg and everolimus 10 mg. Grade 3/4 toxicity included thrombocytopenia (64%), neutropenia (47%), anemia (20%), infection (10%), fatigue (7%) and dyspnea (7%). A total of 10 patients (33%) (indolent lymphoma, T-cell lymphoma, mantle cell lymphoma, and Hodgkin lymphoma) achieved objective responses. In patients with Hodgkin lymphoma (n=14), overall response rate was 43% with complete response rate of 15%. In patients with Hodgkin lymhpoma, multiple serum cytokine levels decreased significantly after treatment with this combination therapy. Of note, clinical responses were associated with a decrease in serum interleukin-5 levels (day 8, p=0.013 and day 15, p=0.021). Conclusions Our data suggest that the combination therapy is active but with significant thrombocytopenia. Future studies should explore alternate scheduling and different compounds that target the same pathways to improve the tolerability of this novel combination. PMID:24097867

  7. Blood concentrations of everolimus are markedly increased by ketoconazole.

    PubMed

    Kovarik, J M; Beyer, D; Bizot, M N; Jiang, Q; Shenouda, M; Schmouder, R L

    2005-05-01

    The authors sought to quantify the influence of the CYP3A and P-glycoprotein inhibitor ketoconazole on the pharmacokinetics of everolimus in healthy subjects. This was a 2-period, single-sequence, crossover study in 12 healthy subjects. In period 1, subjects received the reference treatment of a single 2-mg dose of everolimus. In period 2, they received the test treatment of ketoconazole 200 mg twice daily for a total of 8 days and a single dose of everolimus coadministered on the fourth day of ketoconazole therapy. The test/reference ratio and 90% confidence interval were derived for everolimus maximum concentration and area under the curve. During ketoconazole coadministration, everolimus maximum concentration increased 3.9-fold (90% confidence interval, 3.4-4.6) from 15 +/- 4 ng/mL to 59 +/- 13 ng/mL. Everolimus area under the curve increased 15.0-fold (90% confidence interval, 13.6-16.6) from 90 +/- 23 ng*h/mL to 1324 +/- 232 ng*h/mL. Everolimus half-life was prolonged by 1.9-fold from 30 +/- 4 hours to 56 +/- 5 hours. Everolimus did not appear to alter ketoconazole predose concentrations. Given the magnitude of this drug interaction, use of ketoconazole should be avoided if possible in everolimus-treated patients. PMID:15831774

  8. The combination of IκB kinase β inhibitor and everolimus modulates expression of interleukin-10 in human T-cell lymphotropic virus type-1-infected T cells.

    PubMed

    Nishioka, Chie; Ikezoe, Takayuki; Yang, Jing; Udaka, Keiko; Yokoyama, Akihito

    2013-03-01

    Adult T-cell leukaemia-lymphoma (ATLL) is an aggressive malignancy of CD4(+)  CD25(+) T lymphocytes, characterized by a severely compromised immunosystem, in which the human T-cell lymphotropic virus type 1 (HTLV-1) has been recognized as the aetiological agent. This study found that an IκB kinase β (IKKβ) inhibitor Bay11-7082 inactivated mammalian target of rapamycin (mTOR), signal transducer and activator of transcription 3 and transcription factor nuclear factor-κB in HTLV-1-infected T cells; this was significantly enhanced in the presence of the mTOR inhibitor everolimus. In addition, Bay11-7082 decreased production of the immunosuppressive cytokine interleukin-10 (IL-10), which was further down-regulated when Bay11-7082 was combined with evelolimus in HTLV-1-infected T and ATLL cells isolated from patients. Interleukin-10 is known to inhibit maturation and the antigen-presenting function of dendritic cells (DCs). The culture media of HTLV-1-infected MT-1 cells, which contained a large amout of IL-10, hampered tumour necrosis factor-α-induced maturation of DCs isolated from healthy volunteers. Culture supernatant of MT-1 cells treated with a combination of Bay11-7082 and everolimus augmented maturation of DCs in association with a decrease in production of IL-10 and enhanced the allostimulatory function of DCs. Similarly, when DCs isolated from patients with ATLL were treated with the combination of Bay11-7082 and everolimus, they were fully matured and their capability to stimulate proliferation of lymphocytes was augmented. Taken together, the combination of Bay11-7082 and everolimus might exhibit immunostimulatory properties in HTLV-1-infected T and ATLL cells isolated from patients, and this combination may be potentially therapeutic to regain the compromised immunosystem in ATLL patients.

  9. Phase II trial of everolimus and erlotinib in patients with platinum-resistant recurrent and/or metastatic head and neck squamous cell carcinoma

    PubMed Central

    Massarelli, E.; Lin, H.; Ginsberg, L. E.; Tran, H. T.; Lee, J. J.; Canales, J. R.; Williams, M. D.; Blumenschein, G. R.; Lu, C.; Heymach, J. V.; Kies, M. S.; Papadimitrakopoulou, V.

    2015-01-01

    Background Enhanced phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway is one of the key adaptive changes accounting for epidermal growth factor receptor (EGFR) inhibitor-resistant growth in head and neck squamous cell carcinoma (HNSCC). We designed a phase II clinical trial of EGFR tyrosine kinase inhibitor (TKI), erlotinib, in association with the mTOR inhibitor, everolimus, based on the hypothesis that the downstream effects of Akt through inhibition of mTOR may enhance the effectiveness of the EGFR-TKI in patients with recurrent/metastatic HNSCC. Patients and methods Patients with histologically or cytologically confirmed platinum-resistant HNSCC received everolimus 5 mg and erlotinib 150 mg daily orally until disease progression, intolerable toxicity, investigator or patient decision. Cytokines and angiogenic factors profile, limited mutation analysis and p16 immunohistochemistry status were included in the biomarker analysis. Results Of the 35 assessable patients, 3 (8%) achieved partial response at 4 weeks, 1 confirmed at 12 weeks; overall response rate at 12 weeks was 2.8%. Twenty-seven (77%) patients achieved disease stabilization at 4 weeks, 11 (31%) confirmed at 12 weeks. Twelve-week progression-free survival (PFS) was 49%, median PFS 11.9 weeks and median overall survival (OS) 10.25 months. High neutrophil gelatinase lipocalin (P = 0.01) and vascular endothelial growth factor (VEGF) (P = 0.04) plasma levels were significantly associated with worse OS. Conclusions The combination of erlotinib and everolimus did not show significant benefit in unselected patients with platinum-resistant metastatic HNSCC despite a manageable toxicity profile. Markers of tumor invasion and hypoxia identify a group of patients with particularly poor prognosis. Clinical trial number NCT00942734. PMID:26025965

  10. Treatment-Related Mortality With Everolimus in Cancer Patients

    PubMed Central

    Wesolowski, Robert; Abdel-Rasoul, Mahmoud; Lustberg, Maryam; Paskell, Maria; Shapiro, Charles L.

    2014-01-01

    Introduction. The overall incidence and odds of fatal adverse events (FAEs) after exposure to everolimus are not well defined. We performed a comprehensive meta-analysis of published randomized controlled trials (RCTs) to determine the role of everolimus in treatment-related mortality in patients with cancer. Methods. PubMed databases and abstracts from the proceedings of the American Society of Clinical Oncology and the San Antonio Breast Cancer Symposium were searched for RCTs of everolimus either alone or in combination with another agent compared with the control arm without everolimus and that reported deaths from an adverse event from January 1966 to July 2013. The primary objective was to determine the difference of FAEs between everolimus-treated patients and control group patients. Results. In total, 2,997 patients with multiple solid tumors from nine RCTs were included. The overall incidence of FAEs in cancer patients treated with everolimus was 0.7% (95% CI 0.3%–1.1%) compared with 0.4% (95% CI 0.0%–0.7%) in cancer patients who did not receive everolimus. The odds ratio of FAEs was greater in everolimus-treated patients (Peto odds ratio = 3.80, 95% CI 1.59–9.07, p = .003). In subgroup analyses, no significant difference was found in the incidence or odds of FAEs by everolimus administration (alone or in combination) or tumor type (breast cancer vs. nonbreast cancer; p = .63). Conclusion. In patients with cancer, everolimus is associated with a small but significant increase in the odds of a treatment-related fatal events. PMID:24794158

  11. The Changes of Lipid Metabolism in Advanced Renal Cell Carcinoma Patients Treated with Everolimus: A New Pharmacodynamic Marker?

    PubMed Central

    Pantano, Francesco; Santoni, Matteo; Procopio, Giuseppe; Rizzo, Mimma; Iacovelli, Roberto; Porta, Camillo; Conti, Alessandro; Lugini, Antonio; Milella, Michele; Galli, Luca; Ortega, Cinzia; Guida, Francesco Maria; Silletta, Marianna; Schinzari, Giovanni; Verzoni, Elena; Modica, Daniela; Crucitti, Pierfilippo; Rauco, Annamaria; Felici, Alessandra; Ballatore, Valentina; Cascinu, Stefano; Tonini, Giuseppe; Carteni, Giacomo; Russo, Antonio; Santini, Daniele

    2015-01-01

    Background Everolimus is a mammalian target of rapamycin (mTOR) inhibitor approved for the treatment of metastatic renal cell carcinoma (mRCC). We aimed to assess the association between the baseline values and treatmentrelated modifications of total serum cholesterol (C), triglycerides (T), body mass index (BMI), fasting blood glucose level (FBG) and blood pressure (BP) levels and the outcome of patients treated with everolimus for mRCC. Methods 177 patients were included in this retrospective analysis. Time to progression (TTP), clinical benefit (CB) and overall survival (OS) were evaluated. Results Basal BMI was significantly higher in patients who experienced a CB (p=0,0145). C,T and C+T raises were significantly associated with baseline BMI (p=0.0412, 0.0283 and 0.0001). Median TTP was significantly longer in patients with T raise compared to patients without T (10 vs 6, p=0.030), C (8 vs 5, p=0.042) and C+T raise (10.9 vs 5.0, p=0.003). At the multivariate analysis, only C+T increase was associated with improved TTP (p=0.005). T raise (21.0 vs 14.0, p=0.002) and C+T increase (21.0 vs 14.0, p=0.006) were correlated with improved OS but were not significant at multivariate analysis. Conclusion C+T raise is an early predictor for everolimus efficacy for patients with mRCC. PMID:25885920

  12. Cabozantinib versus everolimus in advanced renal cell carcinoma

    PubMed Central

    Choueiri, Toni K.; Escudier, Bernard; Powles, Thomas; Mainwaring, Paul; Rini, Brian I.; Donskov, Frede; Hammers, Hans; Hutson, Thomas E.; Lee, Jae-Lyun; Peltola, Katriina; Roth, Bruce J.; Bjarnason, Georg A.; Géczi, Lajos; Keam, Bhumsuk; Moroto, Pablo; Heng, Daniel Y. C.; Schmidinger, Manuela; Kantoff, Philip W.; Borgman, Anne; Hessel, Colin; Scheffold, Christian; Schwab, Gisela M.; Tannir, Nizar M.; Motzer, Robert J.

    2016-01-01

    Background Cabozantinib is an oral small molecule tyrosine kinase inhibitor that targets vascular endothelial growth factor receptor (VEGFR) as well as MET and AXL; each has been implicated in metastatic renal cell carcinoma (RCC) pathobiology or development of resistance to antiangiogenic drugs. This randomized open-label phase 3 trial evaluated the efficacy of cabozantinib compared to everolimus in RCC patients who progressed after VEGFR-targeted therapy. Methods The trial randomized 658 patients to receive cabozantinib at a dose of 60 mg daily, or everolimus at a dose of 10 mg daily. The primary endpoint was progression-free survival. Secondary efficacy endpoints were overall survival and objective response rate. Results Median progression-free survival was 7.4 months with cabozantinib and 3.8 months with everolimus. The risk of progression or death was 42% lower with cabozantinib compared to everolimus (hazard ratio, 0.58; 95% confidence interval [CI] 0.45 to 0.75; P < 0.001). Objective response rates were 21% with cabozantinib and 5% with everolimus (P < 0.001). A planned interim analysis showed that overall survival was improved with cabozantinib (hazard ratio, 0.67; 95% CI, 0.51 to 0.89; P = 0.005) but did not cross the significance boundary. Adverse events (grade 3 or 4, regardless of causality) were reported in 74% of cabozantinib patients and 65% of everolimus patients. Discontinuation of study treatment for adverse events occurred in 9.1% of cabozantinib patients and 10% of everolimus patients. Conclusions Cabozantinib improved progression-free survival compared to everolimus in RCC patients who progressed after VEGFR-targeted therapy. PMID:26406150

  13. PIK3CA genotype and a PIK3CA mutation-related gene signature and response to everolimus and letrozole in estrogen receptor positive breast cancer.

    PubMed

    Loi, Sherene; Michiels, Stefan; Baselga, Jose; Bartlett, John M S; Singhal, Sandeep K; Sabine, Vicky S; Sims, Andrew H; Sahmoud, Tarek; Dixon, J Michael; Piccart, Martine J; Sotiriou, Christos

    2013-01-01

    The phosphatidylinositol 3' kinase (PI3K) pathway is commonly activated in breast cancer and aberrations such as PI3K mutations are common. Recent exciting clinical trial results in advanced estrogen receptor-positive (ER) breast cancer support mTOR activation is a major means of estrogen-independent tumor growth. Hence the means to identify a responsive breast cancer population that would most benefit from these compounds in the adjuvant or earlier stage setting is of high interest. Here we study PIK3CA genotype as well as a previously reported PI3K/mTOR-pathway gene signature (PIK3CA-GS) and their ability to estimate the level of PI3K pathway activation in two clinical trials of newly diagnosed ER-positive breast cancer patients- a total of 81 patients- one of which was randomized between letrozole and placebo vs letrozole and everolimus. The main objectives were to correlate the baseline PIK3CA genotype and GS with the relative change from baseline to day 15 in Ki67 (which has been shown to be prognostic in breast cancer) and phosphorylated S6 (S240) immunohistochemistry (a substrate of mTOR). In the randomized dataset, the PIK3CA-GS could identify those patients with the largest relative decreases in Ki67 to letrozole/everolimus (R = -0.43, p = 0.008) compared with letrozole/placebo (R = 0.07, p = 0.58; interaction test p = 0.02). In a second dataset of pre-surgical everolimus alone, the PIK3CA-GS was not significantly correlated with relative change in Ki67 (R = -0.11, p = 0.37) but with relative change in phosphorlyated S6 (S240) (R = -0.46, p = 0.028). PIK3CA genotype was not significantly associated with any endpoint in either datasets. Our results suggest that the PIK3CA-GS has potential to identify those ER-positive BCs who may benefit from the addition of everolimus to letrozole. Further evaluation of the PIK3CA-GS as a predictive biomarker is warranted as it may facilitate better selection of responsive patient populations for mTOR inhibition in

  14. A Small Molecule Screen Exposes mTOR Signaling Pathway Involvement in Radiation-Induced Apoptosis.

    PubMed

    Sharlow, Elizabeth R; Leimgruber, Stephanie; Lira, Ana; McConnell, Michael J; Norambuena, Andrés; Bloom, George S; Epperly, Michael W; Greenberger, Joel S; Lazo, John S

    2016-05-20

    Individuals are at risk of exposure to acute ionizing radiation (IR) from a nuclear accident or terrorism, but we lack effective therapies to mitigate the lethal IR effects. In the current study, we exploited an optimized, cell-based, high throughput screening assay to interrogate a small molecule library comprising 3437 known pharmacologically active compounds for mitigation against IR-induced apoptosis. Thirty-three library compounds significantly reduced apoptosis when administered 1 h after 4 Gy IR. Two- or three-dimensional computational structural analyses of the compounds indicated only one or two chemical clusters with most of the compounds being unique structures. The mechanistic target of rapamycin complex 1 (mTORC1) inhibitor, rapamycin, was the most potent compound, and it mitigated apoptosis by 50% at 200 ± 50 pM. Other mTOR inhibitors, namely everolimus, AZD8055, and torin 1, also suppressed apoptosis, providing additional pharmacological evidence for mTOR pathway involvement in regulating cell death after IR. Everolimus and torin 1 treatment after IR decreased the S phase population and enforced both G1 and G2 phase arrest. This prorogation of cell cycle progression was accompanied by decreased IR-induced DNA damage measured by γH2AX phosphorylation at Ser139. RNA interference-mediated knockdown of the respective mTORC1 and mTORC2 subunits, Raptor or Rictor, also mitigated IR-induced apoptosis. Collectively, this study suggests a central role for the mTOR signaling in the cytotoxic response to IR and offers a useful platform to probe for additional agents. PMID:26938669

  15. Anastrozole and everolimus in advanced gynecologic and breast malignancies: activity and molecular alterations in the PI3K/AKT/mTOR pathway

    PubMed Central

    Wheler, Jennifer J.; Moulder, Stacy L.; Naing, Aung; Janku, Filip; Piha-Paul, Sarina A.; Falchook, Gerald S.; Zinner, Ralph; Tsimberidou, Apostolia M.; Fu, Siqing; Hong, David S.; Atkins, Johnique T.; Yelensky, Roman; Stephens, Philip J.; Kurzrock, Razelle

    2014-01-01

    Background: Since PI3K/AKT/mTOR pathway activation diminishes the effects of hormone therapy, combining aromatase inhibitors (anatrozole) with mTOR inhibitors (everolimus) was investigated. Patients and Methods: We evaluated anastrozole and everolimus in 55 patients with metastatic estrogen (ER) and/or progesterone receptor (PR)-positive breast and gynecologic tumors. Endpoints were safety, antitumor activity and molecular correlates. Results: Full doses of anastrozole (1 mg PO daily) and everolimus (10 mg PO daily) were well tolerated. Twelve of 50 evaluable patients (24%) (median = 3 prior therapies) achieved stable disease (SD) ≥ 6 months/partial response (PR)/complete response (CR) (n = 5 (10%) with PR/CR): 9 of 32 (28%) with breast cancer (n=5 (16%) with PR/CR); 2 of 10 (20%), ovarian cancer; and 1 of 6 (17%), endometrial cancer. Six of 22 patients (27%) with molecular alterations in the PI3K/AKT/mTOR pathway achieved SD ≥ 6 months/PR/CR. Six of 8 patients (75%) with SD ≥ 6 months/PR/CR with molecular testing demonstrated at least one alteration in the PI3K/AKT/mTOR pathway: mutations in PIK3CA (n=3) and AKT1 (n=1) or PTEN loss (n=3). All three responders (CR (n = 1); PR (n=2)) who had next generation sequencing demonstrated additional alterations: amplifications in CCNE1, IRS2, MCL1, CCND1, FGFR1 and MYC and a rearrangement in PRKDC. Conclusions: Combination anastrozole and everolimus is well tolerated at full approved doses, and is active in heavily-pretreated patients with ER and/or PR-positive breast, ovarian and endometrial cancers. Responses were observed in patients with multiple molecular aberrations. Clinical Trails Included: NCT01197170 PMID:24912489

  16. The combination of IκB kinase β inhibitor and everolimus modulates expression of interleukin‐10 in human T‐cell lymphotropic virus type‐1‐infected T cells

    PubMed Central

    Nishioka, Chie; Ikezoe, Takayuki; Yang, Jing; Udaka, Keiko; Yokoyama, Akihito

    2013-01-01

    Summary Adult T‐cell leukaemia‐lymphoma (ATLL) is an aggressive malignancy of CD4+ CD25+ T lymphocytes, characterized by a severely compromised immunosystem, in which the human T‐cell lymphotropic virus type 1 (HTLV‐1) has been recognized as the aetiological agent. This study found that an IκB kinase β (IKKβ) inhibitor Bay11‐7082 inactivated mammalian target of rapamycin (mTOR), signal transducer and activator of transcription 3 and transcription factor nuclear factor‐κB in HTLV‐1‐infected T cells; this was significantly enhanced in the presence of the mTOR inhibitor everolimus. In addition, Bay11‐7082 decreased production of the immunosuppressive cytokine interleukin‐10 (IL‐10), which was further down‐regulated when Bay11‐7082 was combined with evelolimus in HTLV‐1‐infected T and ATLL cells isolated from patients. Interleukin‐10 is known to inhibit maturation and the antigen‐presenting function of dendritic cells (DCs). The culture media of HTLV‐1‐infected MT‐1 cells, which contained a large amout of IL‐10, hampered tumour necrosis factor‐α‐induced maturation of DCs isolated from healthy volunteers. Culture supernatant of MT‐1 cells treated with a combination of Bay11‐7082 and everolimus augmented maturation of DCs in association with a decrease in production of IL‐10 and enhanced the allostimulatory function of DCs. Similarly, when DCs isolated from patients with ATLL were treated with the combination of Bay11‐7082 and everolimus, they were fully matured and their capability to stimulate proliferation of lymphocytes was augmented. Taken together, the combination of Bay11‐7082 and everolimus might exhibit immunostimulatory properties in HTLV‐1‐infected T and ATLL cells isolated from patients, and this combination may be potentially therapeutic to regain the compromised immunosystem in ATLL patients. PMID:23278479

  17. mTOR inhibitors counteract tamoxifen-induced activation of breast cancer stem cells.

    PubMed

    Karthik, Govindasamy-Muralidharan; Ma, Ran; Lövrot, John; Kis, Lorand Levente; Lindh, Claes; Blomquist, Lennart; Fredriksson, Irma; Bergh, Jonas; Hartman, Johan

    2015-10-10

    Breast cancer cells with stem cell characteristics (CSC) are a distinct cell population with phenotypic similarities to mammary stem cells. CSCs are important drivers of tumorigenesis and the metastatic process. Tamoxifen is the most widely used hormonal therapy for estrogen receptor (ER) positive cancers. In our study, tamoxifen was effective in reducing proliferation of ER + adherent cancer cells, but not their CSC population. We isolated, expanded and incubated CSC from seven breast cancers with or without tamoxifen. By genome-wide transcriptional analysis we identified tamoxifen-induced transcriptional pathways associated with ribosomal biogenesis and mRNA translation, both regulated by the mTOR-pathway. We observed induction of the key mTOR downstream targets S6K1, S6RP and 4E-BP1 in-patient derived CSCs by tamoxifen on protein level. Using the mTOR inhibitors rapamycin, everolimus and PF-04691502 (a dual PI3K/mTOR inhibitor) and in combination with tamoxifen, significant reduction in mammosphere formation was observed. Hence, we suggest that the CSC population play a significant role during endocrine resistance through activity of the mTOR pathway. In addition, tamoxifen further stimulates the mTOR-pathway but can be antagonized using mTOR-inhibitors. PMID:26208432

  18. Mutant p53 proteins counteract autophagic mechanism sensitizing cancer cells to mTOR inhibition.

    PubMed

    Cordani, Marco; Oppici, Elisa; Dando, Ilaria; Butturini, Elena; Dalla Pozza, Elisa; Nadal-Serrano, Mercedes; Oliver, Jordi; Roca, Pilar; Mariotto, Sofia; Cellini, Barbara; Blandino, Giovanni; Palmieri, Marta; Di Agostino, Silvia; Donadelli, Massimo

    2016-08-01

    Mutations in TP53 gene play a pivotal role in tumorigenesis and cancer development. Here, we report that gain-of-function mutant p53 proteins inhibit the autophagic pathway favoring antiapoptotic effects as well as proliferation of pancreas and breast cancer cells. We found that mutant p53 significantly counteracts the formation of autophagic vesicles and their fusion with lysosomes throughout the repression of some key autophagy-related proteins and enzymes as BECN1 (and P-BECN1), DRAM1, ATG12, SESN1/2 and P-AMPK with the concomitant stimulation of mTOR signaling. As a paradigm of this mechanism, we show that atg12 gene repression was mediated by the recruitment of the p50 NF-κB/mutant p53 protein complex onto the atg12 promoter. Either mutant p53 or p50 NF-κB depletion downregulates atg12 gene expression. We further correlated the low expression levels of autophagic genes (atg12, becn1, sesn1, and dram1) with a reduced relapse free survival (RFS) and distant metastasis free survival (DMFS) of breast cancer patients carrying TP53 gene mutations conferring a prognostic value to this mutant p53-and autophagy-related signature. Interestingly, the mutant p53-driven mTOR stimulation sensitized cancer cells to the treatment with the mTOR inhibitor everolimus. All these results reveal a novel mechanism through which mutant p53 proteins promote cancer cell proliferation with the concomitant inhibition of autophagy.

  19. Sirolimus and Everolimus Pathway: Reviewing Candidate Genes Influencing Their Intracellular Effects

    PubMed Central

    Granata, Simona; Dalla Gassa, Alessandra; Carraro, Amedeo; Brunelli, Matteo; Stallone, Giovanni; Lupo, Antonio; Zaza, Gianluigi

    2016-01-01

    Sirolimus (SRL) and everolimus (EVR) are mammalian targets of rapamycin inhibitors (mTOR-I) largely employed in renal transplantation and oncology as immunosuppressive/antiproliferative agents. SRL was the first mTOR-I produced by the bacterium Streptomyces hygroscopicus and approved for several medical purposes. EVR, derived from SRL, contains a 2-hydroxy-ethyl chain in the 40th position that makes the drug more hydrophilic than SRL and increases oral bioavailability. Their main mechanism of action is the inhibition of the mTOR complex 1 and the regulation of factors involved in a several crucial cellular functions including: protein synthesis, regulation of angiogenesis, lipid biosynthesis, mitochondrial biogenesis and function, cell cycle, and autophagy. Most of the proteins/enzymes belonging to the aforementioned biological processes are encoded by numerous and tightly regulated genes. However, at the moment, the polygenic influence on SRL/EVR cellular effects is still not completely defined, and its comprehension represents a key challenge for researchers. Therefore, to obtain a complete picture of the cellular network connected to SRL/EVR, we decided to review major evidences available in the literature regarding the genetic influence on mTOR-I biology/pharmacology and to build, for the first time, a useful and specific “SRL/EVR genes-focused pathway”, possibly employable as a starting point for future in-depth research projects. PMID:27187382

  20. The vascular disrupting agent BNC105 potentiates the efficacy of VEGF and mTOR inhibitors in renal and breast cancer.

    PubMed

    Inglis, Daniel J; Lavranos, Tina C; Beaumont, Donna M; Leske, Annabell F; Brown, Chloe K; Hall, Allison J; Kremmidiotis, Gabriel

    2014-01-01

    BNC105 is a tubulin targeting compound that selectively disrupts vasculature within solid tumors. The severe tumor hypoxia and necrosis that ensues translates to short term tumor growth inhibition. We sought to identify the molecular and cellular events activated following BNC105 treatment that drives tumor recovery. We investigated tumor adaptation to BNC105-induced hypoxia in animal models of breast and renal cancer. HIF-1α and GLUT-1 were found to be strongly upregulated by BNC105 as was the VEGF signaling axis. Phosphorylation of mTOR, 4E-BP-1 and elF2α were upregulated, consistent with increased protein synthesis and increased expression of VEGF-A. We sought to investigate the potential therapeutic utility of combining BNC105 with agents targeting VEGF and mTOR signaling. Bevacizumab and pazopanib target the VEGF axis and have been approved for first line use in renal cancer. Everolimus targets mTOR and is currently approved in second line therapy of renal and particular breast cancers. We combined these agents with BNC105 to explore the effects on tumor vasculature, tumor growth inhibition and animal survival. Bevacizumab hindered tumor vascular recovery following BNC105 treatment leading to greater tumor growth inhibition in a breast cancer model. Consistent with this, addition of BNC105 to pazopanib treatment resulted in a significant increase in survival in an orthotopic renal cancer model. Combination treatment of BNC105 with everolimus also increased tumor growth inhibition. BNC105 is currently being evaluated in a randomized phase II clinical trial in combination with everolimus in renal cancer.

  1. A randomized, controlled study to assess the conversion from calcineurin-inhibitors to everolimus after liver transplantation--PROTECT.

    PubMed

    Fischer, L; Klempnauer, J; Beckebaum, S; Metselaar, H J; Neuhaus, P; Schemmer, P; Settmacher, U; Heyne, N; Clavien, P-A; Muehlbacher, F; Morard, I; Wolters, H; Vogel, W; Becker, T; Sterneck, M; Lehner, F; Klein, C; Kazemier, G; Pascher, A; Schmidt, J; Rauchfuss, F; Schnitzbauer, A; Nadalin, S; Hack, M; Ladenburger, S; Schlitt, H J

    2012-07-01

    Posttransplant immunosuppression with calcineurin inhibitors (CNIs) is associated with impaired renal function, while mTor inhibitors such as everolimus may provide a renal-sparing alternative. In this randomized 1-year study in patients with liver transplantation (LTx), we sought to assess the effects of everolimus on glomerular filtration rate (GFR) after conversion from CNIs compared to continued CNI treatment. Eligible study patients received basiliximab induction, CNI with/without corticosteroids for 4 weeks post-LTx, and were then randomized (if GFR > 50 mL/min) to continued CNIs (N = 102) or subsequent conversion to EVR (N = 101). Mean calculated GFR 11 months postrandomization (ITT population) revealed no significant difference between treatments using the Cockcroft-Gault formula (-2.9 mL/min in favor of EVR, 95%-CI: [-10.659; 4.814], p = 0.46), whereas use of the MDRD formula showed superiority for EVR (-7.8 mL/min, 95%-CI: [-14.366; -1.191], p = 0.021). Rates of mortality (EVR: 4.2% vs. CNI: 4.1%), biopsy-proven acute rejection (17.7% vs. 15.3%), and efficacy failure (20.8% vs. 20.4%) were similar. Infections, leukocytopenia, hyperlipidemia and treatment discontinuations occurred more frequently in the EVR group. No hepatic artery thrombosis and no excess of wound healing impairment were noted. Conversion from CNI-based to EVR-based immunosuppression proved to be a safe alternative post-LTx that deserves further investigation in terms of nephroprotection.

  2. Adenosine triphosphate-competitive mTOR inhibitors: a new class of immunosuppressive agents that inhibit allograft rejection.

    PubMed

    Rosborough, B R; Raïch-Regué, D; Liu, Q; Venkataramanan, R; Turnquist, H R; Thomson, A W

    2014-09-01

    The mechanistic/mammalian target of rapamycin (mTOR) is inhibited clinically to suppress T cell function and prevent allograft rejection. mTOR is the kinase subunit of two mTOR-containing complexes, mTOR complex (mTORC) 1 and 2. Although mTORC1 is inhibited by the macrolide immunosuppressant rapamycin (RAPA), its efficacy may be limited by its inability to block mTORC1 completely and its limited effect on mTORC2. Adenosine triphosphate (ATP)-competitive mTOR inhibitors are an emerging class of mTOR inhibitors that compete with ATP at the mTOR active site and inhibit any mTOR-containing complex. Since this class of compounds has not been investigated for their immunosuppressive potential, our goal was to determine the influence of a prototypic ATP-competitive mTOR inhibitor on allograft survival. AZD8055 proved to be a potent suppressor of T cell proliferation. Moreover, a short, 10-day course of the agent successfully prolonged murine MHC-mismatched, vascularized heart transplant survival. This therapeutic effect was associated with increased graft-infiltrating regulatory T cells and reduced CD4(+) and CD8(+) T cell interferon-γ production. These studies establish for the first time, that ATP-competitive mTOR inhibition can prolong organ allograft survival and warrant further investigation of this next generation mTOR inhibitors.

  3. Novel nervous and multi-system regenerative therapeutic strategies for diabetes mellitus with mTOR

    PubMed Central

    Maiese, Kenneth

    2016-01-01

    Throughout the globe, diabetes mellitus (DM) is increasing in incidence with limited therapies presently available to prevent or resolve the significant complications of this disorder. DM impacts multiple organs and affects all components of the central and peripheral nervous systems that can range from dementia to diabetic neuropathy. The mechanistic target of rapamycin (mTOR) is a promising agent for the development of novel regenerative strategies for the treatment of DM. mTOR and its related signaling pathways impact multiple metabolic parameters that include cellular metabolic homeostasis, insulin resistance, insulin secretion, stem cell proliferation and differentiation, pancreatic β-cell function, and programmed cell death with apoptosis and autophagy. mTOR is central element for the protein complexes mTOR Complex 1 (mTORC1) and mTOR Complex 2 (mTORC2) and is a critical component for a number of signaling pathways that involve phosphoinositide 3-kinase (PI 3-K), protein kinase B (Akt), AMP activated protein kinase (AMPK), silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), Wnt1 inducible signaling pathway protein 1 (WISP1), and growth factors. As a result, mTOR represents an exciting target to offer new clinical avenues for the treatment of DM and the complications of this disease. Future studies directed to elucidate the delicate balance mTOR holds over cellular metabolism and the impact of its broad signaling pathways should foster the translation of these targets into effective clinical regimens for DM. PMID:27127460

  4. Novel nervous and multi-system regenerative therapeutic strategies for diabetes mellitus with mTOR.

    PubMed

    Maiese, Kenneth

    2016-03-01

    Throughout the globe, diabetes mellitus (DM) is increasing in incidence with limited therapies presently available to prevent or resolve the significant complications of this disorder. DM impacts multiple organs and affects all components of the central and peripheral nervous systems that can range from dementia to diabetic neuropathy. The mechanistic target of rapamycin (mTOR) is a promising agent for the development of novel regenerative strategies for the treatment of DM. mTOR and its related signaling pathways impact multiple metabolic parameters that include cellular metabolic homeostasis, insulin resistance, insulin secretion, stem cell proliferation and differentiation, pancreatic β-cell function, and programmed cell death with apoptosis and autophagy. mTOR is central element for the protein complexes mTOR Complex 1 (mTORC1) and mTOR Complex 2 (mTORC2) and is a critical component for a number of signaling pathways that involve phosphoinositide 3-kinase (PI 3-K), protein kinase B (Akt), AMP activated protein kinase (AMPK), silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), Wnt1 inducible signaling pathway protein 1 (WISP1), and growth factors. As a result, mTOR represents an exciting target to offer new clinical avenues for the treatment of DM and the complications of this disease. Future studies directed to elucidate the delicate balance mTOR holds over cellular metabolism and the impact of its broad signaling pathways should foster the translation of these targets into effective clinical regimens for DM.

  5. Aspirin may inhibit angiogenesis and induce autophagy by inhibiting mTOR signaling pathway in murine hepatocarcinoma and sarcoma models

    PubMed Central

    Zhao, Qianqian; Wang, Zhaopeng; Wang, Zhaoxia; Wu, Licun; Zhang, Weidong

    2016-01-01

    Aspirin is known to have inhibitory effects on growth development in various types of tumor. In previous studies, it was observed to inhibit angiogenesis by downregulating the expression of vascular endothelial growth factor-A (VEGF-A). In the present study, murine H22 hepatocarcinoma and S180 sarcoma models were used to ascertain whether aspirin could inhibit angiogenesis and promote autophagy in tumors. Tumor-bearing mice were randomly divided into four groups with 10 mice per group: i) no treatment; ii) low-dose aspirin (100 mg/kg); iii) high-dose aspirin (400 mg/kg); iv) everolimus group (4 mg/kg). The effects of high-dose aspirin were validated through preliminary experiments. The drug treatment was administered every day for 14 days. The tumor size was measured every other day and then the tumor growth curve was plotted, and the tumor inhibitory rates were calculated. The expression levels of phosphorylated mammalian target of rapamycin (p-mTOR), hypoxia-inducible factor-1α (HIF-1α), VEGF-A, UNC-51-like kinase-1 (ULK1) and microtubule-associated protein 1 light chain 3A (LC3A) were detected by immunohistochemistry and western blot analysis, respectively. We observed that tumor growth delay was achieved in both H22 hepatocarcinoma and S180 sarcoma models following treatment with aspirin. The tumor growth inhibition rates induced by low and high-dose aspirin and everolimus were 19.6, 33.6 and 53.7% (P<0.05) in H22 hepatocarcinoma, and 25.7, 40.6 and 48.7% (P<0.05) in S180 sarcoma. The immunohistochemistry and western blot analysis data from the models revealed that the expression of p-mTOR, HIF-1α and VEGF-A was decreased, while the expression of ULK1 and LC3A was increased following treatment with aspirin and everolimus. The changes were more apparent in the high-dose aspirin and everolimus groups (P<0.01). The inhibitory action of aspirin and everolimus on tumor angiogenesis may be through inhibiting the expression of p-mTOR, HIF-1α and VEGF

  6. Aspirin may inhibit angiogenesis and induce autophagy by inhibiting mTOR signaling pathway in murine hepatocarcinoma and sarcoma models

    PubMed Central

    Zhao, Qianqian; Wang, Zhaopeng; Wang, Zhaoxia; Wu, Licun; Zhang, Weidong

    2016-01-01

    Aspirin is known to have inhibitory effects on growth development in various types of tumor. In previous studies, it was observed to inhibit angiogenesis by downregulating the expression of vascular endothelial growth factor-A (VEGF-A). In the present study, murine H22 hepatocarcinoma and S180 sarcoma models were used to ascertain whether aspirin could inhibit angiogenesis and promote autophagy in tumors. Tumor-bearing mice were randomly divided into four groups with 10 mice per group: i) no treatment; ii) low-dose aspirin (100 mg/kg); iii) high-dose aspirin (400 mg/kg); iv) everolimus group (4 mg/kg). The effects of high-dose aspirin were validated through preliminary experiments. The drug treatment was administered every day for 14 days. The tumor size was measured every other day and then the tumor growth curve was plotted, and the tumor inhibitory rates were calculated. The expression levels of phosphorylated mammalian target of rapamycin (p-mTOR), hypoxia-inducible factor-1α (HIF-1α), VEGF-A, UNC-51-like kinase-1 (ULK1) and microtubule-associated protein 1 light chain 3A (LC3A) were detected by immunohistochemistry and western blot analysis, respectively. We observed that tumor growth delay was achieved in both H22 hepatocarcinoma and S180 sarcoma models following treatment with aspirin. The tumor growth inhibition rates induced by low and high-dose aspirin and everolimus were 19.6, 33.6 and 53.7% (P<0.05) in H22 hepatocarcinoma, and 25.7, 40.6 and 48.7% (P<0.05) in S180 sarcoma. The immunohistochemistry and western blot analysis data from the models revealed that the expression of p-mTOR, HIF-1α and VEGF-A was decreased, while the expression of ULK1 and LC3A was increased following treatment with aspirin and everolimus. The changes were more apparent in the high-dose aspirin and everolimus groups (P<0.01). The inhibitory action of aspirin and everolimus on tumor angiogenesis may be through inhibiting the expression of p-mTOR, HIF-1α and VEGF

  7. mTOR inhibitors in cancer therapy

    PubMed Central

    Xie, Jianling; Wang, Xuemin; Proud, Christopher G.

    2016-01-01

    The mammalian target of rapamycin, mTOR, plays key roles in cell growth and proliferation, acting at the catalytic subunit of two protein kinase complexes: mTOR complexes 1 and 2 (mTORC1/2). mTORC1 signaling is switched on by several oncogenic signaling pathways and is accordingly hyperactive in the majority of cancers. Inhibiting mTORC1 signaling has therefore attracted great attention as an anti-cancer therapy. However, progress in using inhibitors of mTOR signaling as therapeutic agents in oncology has been limited by a number of factors, including the fact that the classic mTOR inhibitor, rapamycin, inhibits only some of the effects of mTOR; the existence of several feedback loops; and the crucial importance of mTOR in normal physiology.

  8. mTOR inhibitors in cancer therapy

    PubMed Central

    Xie, Jianling; Wang, Xuemin; Proud, Christopher G.

    2016-01-01

    The mammalian target of rapamycin, mTOR, plays key roles in cell growth and proliferation, acting at the catalytic subunit of two protein kinase complexes: mTOR complexes 1 and 2 (mTORC1/2). mTORC1 signaling is switched on by several oncogenic signaling pathways and is accordingly hyperactive in the majority of cancers. Inhibiting mTORC1 signaling has therefore attracted great attention as an anti-cancer therapy. However, progress in using inhibitors of mTOR signaling as therapeutic agents in oncology has been limited by a number of factors, including the fact that the classic mTOR inhibitor, rapamycin, inhibits only some of the effects of mTOR; the existence of several feedback loops; and the crucial importance of mTOR in normal physiology. PMID:27635236

  9. mTOR inhibitors in cancer therapy.

    PubMed

    Xie, Jianling; Wang, Xuemin; Proud, Christopher G

    2016-01-01

    The mammalian target of rapamycin, mTOR, plays key roles in cell growth and proliferation, acting at the catalytic subunit of two protein kinase complexes: mTOR complexes 1 and 2 (mTORC1/2). mTORC1 signaling is switched on by several oncogenic signaling pathways and is accordingly hyperactive in the majority of cancers. Inhibiting mTORC1 signaling has therefore attracted great attention as an anti-cancer therapy. However, progress in using inhibitors of mTOR signaling as therapeutic agents in oncology has been limited by a number of factors, including the fact that the classic mTOR inhibitor, rapamycin, inhibits only some of the effects of mTOR; the existence of several feedback loops; and the crucial importance of mTOR in normal physiology. PMID:27635236

  10. Recommendations for the use of everolimus (Certican) in heart transplantation: results from the second German-Austrian Certican Consensus Conference.

    PubMed

    Rothenburger, Markus; Zuckermann, Andreas; Bara, Christoph; Hummel, Manfred; Strüber, Martin; Hirt, Stephan; Lehmkuhl, Hans

    2007-04-01

    Everolimus (Certican; Novartis Pharma AG, Basel, Switzerland) represents the latest generation of proliferation signal inhibitors (PSIs). Everolimus is indicated for use as an immunosuppressive drug in renal and heart transplantation. This report reflects the recommendations of the second German-Austrian Certican Consensus Conference, held in January 2006, for the clinical use of everolimus. PMID:17403469

  11. Everolimus for Primary Intestinal Lymphangiectasia With Protein-Losing Enteropathy.

    PubMed

    Ozeki, Michio; Hori, Tomohiro; Kanda, Kaori; Kawamoto, Norio; Ibuka, Takashi; Miyazaki, Tatsuhiko; Fukao, Toshiyuki

    2016-03-01

    Primary intestinal lymphangiectasia (PIL), also known as Waldmann's disease, is an exudative enteropathy resulting from morphologic abnormalities in the intestinal lymphatics. In this article, we describe a 12-year-old boy with PIL that led to protein-losing enteropathy characterized by diarrhea, hypoalbuminemia associated with edema (serum albumin level: 1.0 g/dL), and hypogammaglobulinemia (serum IgG level: 144 mg/dL). Severe hypoalbuminemia, electrolyte abnormalities, and tetany persisted despite a low-fat diet and propranolol. Everolimus (1.6 mg/m(2)/day) was added to his treatment as an antiangiogenic agent. With everolimus treatment, the patient's diarrhea resolved and replacement therapy for hypoproteinemia was less frequent. Hematologic and scintigraphy findings also improved (serum albumin level: 2.5 g/dL). There were no adverse reactions during the 12-month follow-up. To the best of our knowledge, this is the first report of everolimus use in a patient with PIL. PMID:26908672

  12. Prospects for mTOR inhibitor use in patients with polycystic kidney disease and hamartomatous diseases.

    PubMed

    Torres, Vicente E; Boletta, Alessandra; Chapman, Arlene; Gattone, Vincent; Pei, York; Qian, Qi; Wallace, Darren P; Weimbs, Thomas; Wüthrich, Rudolf P

    2010-07-01

    Mammalian target of rapamycin (mTOR) is the core component of two complexes, mTORC1 and mTORC2. mTORC1 is inhibited by rapamycin and analogues. mTORC2 is impeded only in some cell types by prolonged exposure to these compounds. mTOR activation is linked to tubular cell proliferation in animal models and human autosomal dominant polycystic kidney disease (ADPKD). mTOR inhibitors impede cell proliferation and cyst growth in polycystic kidney disease (PKD) models. After renal transplantation, two small retrospective studies suggested that mTOR was more effective than calcineurin inhibitor-based immunosuppression in limiting kidney and/or liver enlargement. By inhibiting vascular remodeling, angiogenesis, and fibrogenesis, mTOR inhibitors may attenuate nephroangiosclerosis, cyst growth, and interstitial fibrosis. Thus, they may benefit ADPKD at multiple levels. However, mTOR inhibition is not without risks and side effects, mostly dose-dependent. Under certain conditions, mTOR inhibition interferes with adaptive increases in renal proliferation necessary for recovery from injury. They restrict Akt activation, nitric oxide synthesis, and endothelial cell survival (downstream from mTORC2) and potentially increase the risk for glomerular and peritubular capillary loss, vasospasm, and hypertension. They impair podocyte integrity pathways and may predispose to glomerular injury. Administration of mTOR inhibitors is discontinued because of side effects in up to 40% of transplant recipients. Currently, treatment with mTOR inhibitors should not be recommended to treat ADPKD. Results of ongoing studies must be awaited and patients informed accordingly. If effective, lower dosages than those used to prevent rejection would minimize side effects. Combination therapy with other effective drugs could improve tolerability and results. PMID:20498248

  13. Mutant p53 proteins counteract autophagic mechanism sensitizing cancer cells to mTOR inhibition.

    PubMed

    Cordani, Marco; Oppici, Elisa; Dando, Ilaria; Butturini, Elena; Dalla Pozza, Elisa; Nadal-Serrano, Mercedes; Oliver, Jordi; Roca, Pilar; Mariotto, Sofia; Cellini, Barbara; Blandino, Giovanni; Palmieri, Marta; Di Agostino, Silvia; Donadelli, Massimo

    2016-08-01

    Mutations in TP53 gene play a pivotal role in tumorigenesis and cancer development. Here, we report that gain-of-function mutant p53 proteins inhibit the autophagic pathway favoring antiapoptotic effects as well as proliferation of pancreas and breast cancer cells. We found that mutant p53 significantly counteracts the formation of autophagic vesicles and their fusion with lysosomes throughout the repression of some key autophagy-related proteins and enzymes as BECN1 (and P-BECN1), DRAM1, ATG12, SESN1/2 and P-AMPK with the concomitant stimulation of mTOR signaling. As a paradigm of this mechanism, we show that atg12 gene repression was mediated by the recruitment of the p50 NF-κB/mutant p53 protein complex onto the atg12 promoter. Either mutant p53 or p50 NF-κB depletion downregulates atg12 gene expression. We further correlated the low expression levels of autophagic genes (atg12, becn1, sesn1, and dram1) with a reduced relapse free survival (RFS) and distant metastasis free survival (DMFS) of breast cancer patients carrying TP53 gene mutations conferring a prognostic value to this mutant p53-and autophagy-related signature. Interestingly, the mutant p53-driven mTOR stimulation sensitized cancer cells to the treatment with the mTOR inhibitor everolimus. All these results reveal a novel mechanism through which mutant p53 proteins promote cancer cell proliferation with the concomitant inhibition of autophagy. PMID:27118659

  14. Co-administration strategy to enhance brain accumulation of vandetanib by modulating P-glycoprotein (P-gp/Abcb1) and breast cancer resistance protein (Bcrp1/Abcg2) mediated efflux with m-TOR inhibitors.

    PubMed

    Minocha, Mukul; Khurana, Varun; Qin, Bin; Pal, Dhananjay; Mitra, Ashim K

    2012-09-15

    The objectives of this study were (i) to characterize the interaction of vandetanib with P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp1) in vitro and in vivo (ii) to study the modulation of P-gp and BCRP mediated efflux of vandetanib with specific transport inhibitors and m-TOR inhibitors, everolimus and temsirolimus. Cellular accumulation and bi-directional transport studies in MDCKII cell monolayers were conducted to delineate the role of efflux transporters on disposition of vandetanib. Brain distribution studies were conducted in male FVB wild-type mice with vandetanib administered intravenously either alone or in the presence of specific inhibitors and m-TOR inhibitors. In vitro studies suggested that vandetanib is a high affinity substrate of Bcrp1 but is not transported by P-gp. Interestingly, in vivo brain distribution studies in FVB wild type mice indicated that vandetanib penetration into the brain is restricted by both Bcrp1 and P-gp mediated active efflux at the blood brain barrier (BBB). Co-administration of elacridar, a dual P-gp/BCRP inhibitor increased the brain to plasma concentration ratio of vandetanib upto 5 fold. Of the two m-TOR pathway inhibitors examined; everolimus showed potent effect on modulating vandetanib brain penetration whereas no significant affect on vandetanib brain uptake was observed following temsirolimus co-administration. This finding could be clinically relevant as everolimus can provide synergistic pharmacological effect in addition to primary role of vandetanib efflux modulation at BBB for the treatment of brain tumors. PMID:22633931

  15. mTOR and the health benefits of exercise.

    PubMed

    Watson, Kurt; Baar, Keith

    2014-12-01

    Exercise is the greatest physiological stress that our bodies experience. For example, during maximal endurance exercise in elite athlete's cardiac output can increase up to 8-fold and the working muscles receive 21-times more blood each minute than at rest. Given the physiological stress associated with exercise and the adaptations that occur to handle this stress, it is not surprising that exercise training is known to prevent or effectively treat a multitude of degenerative conditions including cardiovascular disease, cancer, diabetes, depression, Alzheimer's disease, Parkinson's disease, and many others. Many of the health benefits of exercise are mediated by the mammalian/mechanistic target of rapamycin (mTOR), either in complex 1 or 2, not only within the working muscle, but also in distant tissues such as fat, liver, and brain. This review will discuss how exercise activates mTOR in diverse tissues and the ways that mTOR is important in the adaptive response that makes us bigger, stronger, and healthier as a result of exercise. PMID:25218794

  16. Everolimus-induced Pneumonitis after Drug-eluting Stent Implantation: A Case Report

    SciTech Connect

    Sakamoto, Susumu Kikuchi, Naoshi; Ichikawa, Atsuo; Sano, Go; Satoh, Keita; Sugino, Keishi; Isobe, Kazutoshi; Takai, Yujiro; Shibuya, Kazutoshi; Homma, Sakae

    2013-08-01

    Despite the wide use of everolimus as an antineoplastic coating agent for coronary stents to reduce the rate of restenosis, little is known about the health hazards of everolimus-eluting stents (EES). We describe a case of pneumonitis that developed 2 months after EES implantation for angina. Lung pathology demonstrated an organizing pneumonia pattern that responded to corticosteroid therapy. Although the efficacy of EES for ischemic heart disease is well established, EES carries a risk of pneumonitis.

  17. Everolimus affects vasculogenic mimicry in renal carcinoma resistant to sunitinib.

    PubMed

    Serova, Maria; Tijeras-Raballand, Annemilaï; Dos Santos, Celia; Martinet, Matthieu; Neuzillet, Cindy; Lopez, Alfred; Mitchell, Dianne C; Bryan, Brad A; Gapihan, Guillaume; Janin, Anne; Bousquet, Guilhem; Riveiro, Maria Eugenia; Bieche, Ivan; Faivre, Sandrine; Raymond, Eric; de Gramont, Armand

    2016-06-21

    Angiogenesis is hallmark of clear cell renal cell carcinogenesis. Anti-angiogenic therapies have been successful in improving disease outcome; however, most patients treated with anti-angiogenic agents will eventually progress. In this study we report that clear cell renal cell carcinoma was associated with vasculogenic mimicry in both mice and human with tumor cells expressing endothelial markers in the vicinity of tumor vessels. We show that vasculogenic mimicry was efficiently targeted by sunitinib but eventually associated with tumor resistance and a more aggressive phenotype both in vitro and in vivo. Re-challenging these resistant tumors in mice, we showed that second-line treatment with everolimus particularly affected vasculogenic mimicry and tumor cell differentiation compared to sorafenib and axitinib. Finally, our results highlighted the phenotypic and genotypic changes at the tumor cell and microenvironment levels during sunitinib response and progression and the subsequent improvement second-line therapies bring to the current renal cell carcinoma treatment paradigm. PMID:27509260

  18. Dissociation of the Pharmacological Effects of THC by mTOR Blockade

    PubMed Central

    Puighermanal, Emma; Busquets-Garcia, Arnau; Gomis-González, Maria; Marsicano, Giovanni; Maldonado, Rafael; Ozaita, Andrés

    2013-01-01

    The potential therapeutic benefits of cannabinoid compounds have raised interest in understanding the molecular mechanisms that underlie cannabinoid-mediated effects. We previously showed that the acute amnesic-like effects of delta9-tetrahydrocannabinol (THC) were prevented by the subchronic inhibition of the mammalian target of rapamycin (mTOR) pathway. In the present study, we assess the relevance of the mTOR pathway in other acute and chronic pharmacological effects of THC. The rapamycin derivative temsirolimus, an inhibitor of the mTOR pathway approved by the Food and Drug Administration, prevents both the anxiogenic- and the amnesic-like effects produced by acute THC. In contrast, THC-induced anxiolysis, hypothermia, hypolocomotion, and antinociception are not sensitive to the mTOR inhibition. In addition, a clear tolerance to THC-induced anxiolysis, hypothermia, hypolocomotion, and antinociception was observed after chronic treatment, but not to its anxiogenic- and amnesic-like effects. Temsirolimus pre-treatment prevented the amnesic-like effects of chronic THC without affecting the downregulation of CB1 receptors (CB1R) induced by this chronic treatment. Instead, temsirolimus blockade after chronic THC cessation did not prevent the residual cognitive deficit produced by chronic THC. Using conditional knockout mice lacking CB1R in GABAergic or glutamatergic neurons, we found that GABAergic CB1Rs are mainly downregulated under chronic THC treatment conditions, and CB1–GABA–KO mice did not develop cognitive deficits after chronic THC exposure. Therefore, mTOR inhibition by temsirolimus allows the segregation of the potentially beneficial effects of cannabinoid agonists, such as the anxiolytic and antinociceptive effects, from the negative effects, such as anxiogenic- and amnesic-like responses. Altogether, these results provide new insights for targeting the endocannabinoid system in order to prevent possible side effects. PMID:23358238

  19. Dissociation of the pharmacological effects of THC by mTOR blockade.

    PubMed

    Puighermanal, Emma; Busquets-Garcia, Arnau; Gomis-González, Maria; Marsicano, Giovanni; Maldonado, Rafael; Ozaita, Andrés

    2013-06-01

    The potential therapeutic benefits of cannabinoid compounds have raised interest in understanding the molecular mechanisms that underlie cannabinoid-mediated effects. We previously showed that the acute amnesic-like effects of delta9-tetrahydrocannabinol (THC) were prevented by the subchronic inhibition of the mammalian target of rapamycin (mTOR) pathway. In the present study, we assess the relevance of the mTOR pathway in other acute and chronic pharmacological effects of THC. The rapamycin derivative temsirolimus, an inhibitor of the mTOR pathway approved by the Food and Drug Administration, prevents both the anxiogenic- and the amnesic-like effects produced by acute THC. In contrast, THC-induced anxiolysis, hypothermia, hypolocomotion, and antinociception are not sensitive to the mTOR inhibition. In addition, a clear tolerance to THC-induced anxiolysis, hypothermia, hypolocomotion, and antinociception was observed after chronic treatment, but not to its anxiogenic- and amnesic-like effects. Temsirolimus pre-treatment prevented the amnesic-like effects of chronic THC without affecting the downregulation of CB1 receptors (CB1R) induced by this chronic treatment. Instead, temsirolimus blockade after chronic THC cessation did not prevent the residual cognitive deficit produced by chronic THC. Using conditional knockout mice lacking CB1R in GABAergic or glutamatergic neurons, we found that GABAergic CB1Rs are mainly downregulated under chronic THC treatment conditions, and CB1-GABA-KO mice did not develop cognitive deficits after chronic THC exposure. Therefore, mTOR inhibition by temsirolimus allows the segregation of the potentially beneficial effects of cannabinoid agonists, such as the anxiolytic and antinociceptive effects, from the negative effects, such as anxiogenic- and amnesic-like responses. Altogether, these results provide new insights for targeting the endocannabinoid system in order to prevent possible side effects.

  20. Direct Evidence of Target Inhibition with anti-VEGF, EGFR, and mTOR Therapies in a Clinical Model of Wound Healing

    PubMed Central

    Jia, Jingquan; Dellinger, Andrew E.; Weiss, Eric S.; Bulusu, Anuradha; Rushing, Christel; Li, Haiyan; Howard, Leigh A.; Kaplan, Neal; Pang, Herbert; Hurwitz, Herbert I.; Nixon, Andrew B.

    2016-01-01

    Purpose In early clinical testing, most novel targeted anti-cancer therapies have limited toxicities and limited efficacy, which complicates dose and schedule selection for these agents. Confirmation of target inhibition is critical for rational drug development; however, repeated tumor biopsies are often impractical and peripheral blood mononuclear cells and normal skin are often inadequate surrogates for tumor tissue. Based upon the similarities of tumor and wound stroma, we have developed a clinical dermal granulation tissue model to evaluate novel targeted therapies. Experimental design A 4mm skin punch biopsy was used to stimulate wound healing and a repeat 5mm punch biopsy was used to harvest the resulting granulation tissue. This assay was performed at pre-treatment and on-treatment evaluating four targeted therapies, bevacizumab, everolimus, erlotinib, and panitumumab, in the context of three different clinical trials. Total and phosphorylated levels VEGFR2, S6RP, and EGFR were evaluated using ELISA-based methodologies. Results Significant and consistent inhibition of VEGF pathway (using VEGFR2 as the readout) was observed in granulation tissue biopsies from patients treated with bevacizumab and everolimus. Additionally, significant and consistent inhibition of mTOR pathway (using S6RP as the readout) was observed in patients treated with everolimus. Lastly, significant inhibition of EGFR pathway (using EGFR as the readout) was observed in patients treated with panitumumab, but this was not observed in patients treated with erlotinib. Conclusion Molecular analyses of dermal granulation tissue can be used as a convenient and quantitative pharmacodynamic biomarker platform for multiple classes of targeted therapies. PMID:25878330

  1. Evaluation of QMS everolimus assay using Hitachi 917 Analyzer: comparison with liquid chromatography/mass spectrometry.

    PubMed

    Dasgupta, Amitava; Davis, Bonnet; Chow, Loretta

    2011-04-01

    Everolimus is an immunosuppressant requiring routine monitoring in whole blood. We evaluated the analytical performance of a new immunoassay for everolimus, Quantitative Microsphere System (QMS) everolimus (Thermo Fisher Scientific), which is CE marked and currently under review by Food and Drug Administration of the United States by comparing results with values obtained by using liquid chromatography/mass spectrometry. The total coefficient of variations (CVs) were 8.3% for low control (mean: 3.8 ng/mL), 6.1% for the medium control (mean: 8.0 ng/mL), and 7.5% for the high control (mean: 14.4 ng/mL) (n = 80 for each control, run over 20 nonconsecutive days). The respective total CVs for patients' pool were 13.3% (mean: 4.0 ng/mL), 7.5% (mean: 8.2 ng/mL), and 8.7% (mean: 11.7 ng/mL) (n = 80 for each patient pool). The assay was linear from a whole-blood everolimus level between 1.5 and 20 ng/mL, and the limit of quantitation was 1.3 ng/mL. Comparison was carried out using 90 renal transplant patient samples, and we observed the following Passing and Bablok linear regression plot: y = 1.11, slope = -0.005 (R = 0.92). This assay was not affected by commonly used 70 drugs, but sirolimus, a drug structurally similar to everolimus, showed 46% cross-reactivity. We conclude that QMS everolimus immunoassay has adequate sensitivity and specificity for the determination of whole-blood everolimus and can be used for routine therapeutic drug monitoring.

  2. Everolimus Stabilizes Podocyte Microtubules via Enhancing TUBB2B and DCDC2 Expression

    PubMed Central

    Jeruschke, Stefanie; Jeruschke, Kay; DiStasio, Andrew; Karaterzi, Sinem; Büscher, Anja K.; Nalbant, Perihan; Klein-Hitpass, Ludger; Hoyer, Peter F.; Weiss, Jürgen; Stottmann, Rolf W.; Weber, Stefanie

    2015-01-01

    Background Glomerular podocytes are highly differentiated cells that are key components of the kidney filtration units. The podocyte cytoskeleton builds the basis for the dynamic podocyte cytoarchitecture and plays a central role for proper podocyte function. Recent studies implicate that immunosuppressive agents including the mTOR-inhibitor everolimus have a protective role directly on the stability of the podocyte actin cytoskeleton. In contrast, a potential stabilization of microtubules by everolimus has not been studied so far. Methods To elucidate mechanisms underlying mTOR-inhibitor mediated cytoskeletal rearrangements, we carried out microarray gene expression studies to identify target genes and corresponding pathways in response to everolimus. We analyzed the effect of everolimus in a puromycin aminonucleoside experimental in vitro model of podocyte injury. Results Upon treatment with puromycin aminonucleoside, microarray analysis revealed gene clusters involved in cytoskeletal reorganization, cell adhesion, migration and extracellular matrix composition to be affected. Everolimus was capable of protecting podocytes from injury, both on transcriptional and protein level. Rescued genes included tubulin beta 2B class IIb (TUBB2B) and doublecortin domain containing 2 (DCDC2), both involved in microtubule structure formation in neuronal cells but not identified in podocytes so far. Validating gene expression data, Western-blot analysis in cultured podocytes demonstrated an increase of TUBB2B and DCDC2 protein after everolimus treatment, and immunohistochemistry in healthy control kidneys confirmed a podocyte-specific expression. Interestingly, Tubb2bbrdp/brdp mice revealed a delay in glomerular podocyte development as showed by podocyte-specific markers Wilm’s tumour 1, Podocin, Nephrin and Synaptopodin. Conclusions Taken together, our study suggests that off-target, non-immune mediated effects of the mTOR-inhibitor everolimus on the podocyte cytoskeleton

  3. Everolimus in the treatment of renal cell carcinoma and neuroendocrine tumors.

    PubMed

    Chan, Hiu-yan; Grossman, Ashley B; Bukowski, Ronald M

    2010-08-01

    Renal cell carcinoma (RCC) and neuroendocrine tumors (NET) are uncommon malignancies, highly resistant to chemotherapy, that have emerged as attractive platforms for evaluating novel targeted regimens. Everolimus is an oral rapamycin derivative within the mammalian target of rapamycin class of agents. Preclinical series have shown that everolimus exhibits anticancer effects in RCC and NET cell lines. A phase 3 placebo-controlled study in advanced clear-cell RCC, known as RECORD-1 (for "REnal Cell cancer treatment with Oral RAD001 given Daily"), documented that everolimus stabilizes tumor progression, prolongs progression-free survival and has acceptable tolerability in patients previously treated with the multikinase inhibitors sunitinib and/or sorafenib. Everolimus has been granted regulatory approval for use in sunitinib-pretreated and/or sorafenib-pretreated advanced RCC and incorporated into clinical practice guidelines, and the RECORD-1 safety data are being used to develop recommendations for managing clinically important adverse events in everolimus-treated patients. Ongoing clinical trials are evaluating everolimus as earlier RCC therapy (first-line for advanced disease and as neoadjuvant therapy), in non-clear-cell tumors, and in combination with various other approved or investigational targeted therapies for RCC. Regarding advanced NET, recently published phase 2 data support the ability of everolimus to improve disease control in patients with advanced NET as monotherapy or in combination with somatostatin analogue therapy, octreotide long-acting release (LAR). Forthcoming data from phase 3 placebo-controlled trials of everolimus, one focused on monotherapy for pancreatic NET and the other on combination use with octreotide LAR for patients with advanced NET and a history of carcinoid syndrome, will provide insight into its future place in NET therapy. The results of a number of ongoing phase 3 evaluations of everolimus will determine its broader

  4. 5-HT(6) receptor recruitment of mTOR as a mechanism for perturbed cognition in schizophrenia.

    PubMed

    Meffre, Julie; Chaumont-Dubel, Séverine; Mannoury la Cour, Clotilde; Loiseau, Florence; Watson, David J G; Dekeyne, Anne; Séveno, Martial; Rivet, Jean-Michel; Gaven, Florence; Déléris, Paul; Hervé, Denis; Fone, Kevin C F; Bockaert, Joël; Millan, Mark J; Marin, Philippe

    2012-10-01

    Cognitive deficits in schizophrenia severely compromise quality of life and are poorly controlled by current antipsychotics. While 5-HT(6) receptor blockade holds special promise, molecular substrates underlying their control of cognition remain unclear. Using a proteomic strategy, we show that 5-HT(6) receptors physically interact with several proteins of the mammalian target of rapamycin (mTOR) pathway, including mTOR. Further, 5-HT(6) receptor activation increased mTOR signalling in rodent prefrontal cortex (PFC). Linking this signalling event to cognitive impairment, the mTOR inhibitor rapamycin prevented deficits in social cognition and novel object discrimination induced by 5-HT(6) agonists. In two developmental models of schizophrenia, specifically neonatal phencyclidine treatment and post-weaning isolation rearing, the activity of mTOR was enhanced in the PFC, and rapamycin, like 5-HT(6) antagonists, reversed these cognitive deficits. These observations suggest that recruitment of mTOR by prefrontal 5-HT(6) receptors contributes to the perturbed cognition in schizophrenia, offering new vistas for its therapeutic control.

  5. Glucose Regulation of Load‐Induced mTOR Signaling and ER Stress in Mammalian Heart

    PubMed Central

    Sen, Shiraj; Kundu, Bijoy K.; Wu, Henry Cheng‐Ju; Hashmi, S. Shahrukh; Guthrie, Patrick; Locke, Landon W.; Roy, R. Jack; Matherne, G. Paul; Berr, Stuart S.; Terwelp, Matthew; Scott, Brian; Carranza, Sylvia; Frazier, O. Howard; Glover, David K.; Dillmann, Wolfgang H.; Gambello, Michael J.; Entman, Mark L.; Taegtmeyer, Heinrich

    2013-01-01

    Background Changes in energy substrate metabolism are first responders to hemodynamic stress in the heart. We have previously shown that hexose‐6‐phosphate levels regulate mammalian target of rapamycin (mTOR) activation in response to insulin. We now tested the hypothesis that inotropic stimulation and increased afterload also regulate mTOR activation via glucose 6‐phosphate (G6P) accumulation. Methods and Results We subjected the working rat heart ex vivo to a high workload in the presence of different energy‐providing substrates including glucose, glucose analogues, and noncarbohydrate substrates. We observed an association between G6P accumulation, mTOR activation, endoplasmic reticulum (ER) stress, and impaired contractile function, all of which were prevented by pretreating animals with rapamycin (mTOR inhibition) or metformin (AMPK activation). The histone deacetylase inhibitor 4‐phenylbutyrate, which relieves ER stress, also improved contractile function. In contrast, adding the glucose analogue 2‐deoxy‐d‐glucose, which is phosphorylated but not further metabolized, to the perfusate resulted in mTOR activation and contractile dysfunction. Next we tested our hypothesis in vivo by transverse aortic constriction in mice. Using a micro‐PET system, we observed enhanced glucose tracer analog uptake and contractile dysfunction preceding dilatation of the left ventricle. In contrast, in hearts overexpressing SERCA2a, ER stress was reduced and contractile function was preserved with hypertrophy. Finally, we examined failing human hearts and found that mechanical unloading decreased G6P levels and ER stress markers. Conclusions We propose that glucose metabolic changes precede and regulate functional (and possibly also structural) remodeling of the heart. We implicate a critical role for G6P in load‐induced mTOR activation and ER stress. PMID:23686371

  6. Fundamental for life: mTOR orchestrates developing biological systems.

    PubMed

    Tee, Andrew R

    2014-12-01

    Mechanistic target of rapamycin (mTOR) (historically known as mammalian target of rapamycin) functions as a master regulator of cell growth control. Although the regulation of protein translation is probably the best understood function of mTOR, it is clear that mTOR governs many additional processes within the cell that together orchestrates organism growth and development. Our 'growing' knowledge of the regulation of mTOR and signalling pathways has broadened significantly over the last few decades. Together, the eight reviews described in this special series on mTOR covers fundamental and up-to-date facets of mTOR function and signalling. The review topics herein underpin the importance of mTOR for developing and maintaining biological systems through the regulation of cellular growth and homeostatic pathways, which is fundamental for life and well-being.

  7. Real-world study of everolimus in advanced progressive neuroendocrine tumors.

    PubMed

    Panzuto, Francesco; Rinzivillo, Maria; Fazio, Nicola; de Braud, Filippo; Luppi, Gabriele; Zatelli, Maria Chiara; Lugli, Francesca; Tomassetti, Paola; Riccardi, Ferdinando; Nuzzo, Carmen; Brizzi, Maria Pia; Faggiano, Antongiulio; Zaniboni, Alberto; Nobili, Elisabetta; Pastorelli, Davide; Cascinu, Stefano; Merlano, Marco; Chiara, Silvana; Antonuzzo, Lorenzo; Funaioli, Chiara; Spada, Francesca; Pusceddu, Sara; Fontana, Annalisa; Ambrosio, Maria Rosaria; Cassano, Alessandra; Campana, Davide; Cartenì, Giacomo; Appetecchia, Marialuisa; Berruti, Alfredo; Colao, Annamaria; Falconi, Massimo; Delle Fave, Gianfranco

    2014-09-01

    Everolimus is a valid therapeutic option for neuroendocrine tumors (NETs); however, data in a real-world setting outside regulatory trials are sparse. The aim of this study was to determine everolimus tolerability and efficacy, in relation to previous treatments, in a compassionate use program. A total of 169 patients with advanced progressive NETs treated with everolimus were enrolled, including 85 with pancreatic NETs (pNETs) and 84 with nonpancreatic NETs (non-pNETs). Previous treatments included somatostatin analogs (92.9%), peptide receptor radionuclide therapy (PRRT; 50.3%), chemotherapy (49.7%), and PRRT and chemotherapy (22.8%). Overall, 85.2% of patients experienced adverse events (AEs), which were severe (grade 3-4) in 46.1%. The most frequent severe AEs were pneumonitis (8.3%), thrombocytopenia (7.7%), anemia (5.3%), and renal failure (3.5%). In patients previously treated with PRRT and chemotherapy, a 12-fold increased risk for severe toxicity was observed, with grade 3-4 AEs reported in 86.8% (vs. 34.3% in other patients). In addition, 63.3% of patients required temporarily everolimus discontinuation due to toxicity. Overall, 27.8% of patients died during a median follow-up of 12 months. Median progression-free survival (PFS) and overall survival (OS) were 12 months and 32 months, respectively. Similar disease control rates, PFS, and OS were reported in pNETs and non-pNETs. In the real-world setting, everolimus is safe and effective for the treatment of NETs of different origins. Higher severe toxicity occurred in patients previously treated with systemic chemotherapy and PRRT. This finding prompts caution when using this drug in pretreated patients and raises the issue of planning for everolimus before PRRT and chemotherapy in the therapeutic algorithm for advanced NETs.

  8. Real-world study of everolimus in advanced progressive neuroendocrine tumors.

    PubMed

    Panzuto, Francesco; Rinzivillo, Maria; Fazio, Nicola; de Braud, Filippo; Luppi, Gabriele; Zatelli, Maria Chiara; Lugli, Francesca; Tomassetti, Paola; Riccardi, Ferdinando; Nuzzo, Carmen; Brizzi, Maria Pia; Faggiano, Antongiulio; Zaniboni, Alberto; Nobili, Elisabetta; Pastorelli, Davide; Cascinu, Stefano; Merlano, Marco; Chiara, Silvana; Antonuzzo, Lorenzo; Funaioli, Chiara; Spada, Francesca; Pusceddu, Sara; Fontana, Annalisa; Ambrosio, Maria Rosaria; Cassano, Alessandra; Campana, Davide; Cartenì, Giacomo; Appetecchia, Marialuisa; Berruti, Alfredo; Colao, Annamaria; Falconi, Massimo; Delle Fave, Gianfranco

    2014-09-01

    Everolimus is a valid therapeutic option for neuroendocrine tumors (NETs); however, data in a real-world setting outside regulatory trials are sparse. The aim of this study was to determine everolimus tolerability and efficacy, in relation to previous treatments, in a compassionate use program. A total of 169 patients with advanced progressive NETs treated with everolimus were enrolled, including 85 with pancreatic NETs (pNETs) and 84 with nonpancreatic NETs (non-pNETs). Previous treatments included somatostatin analogs (92.9%), peptide receptor radionuclide therapy (PRRT; 50.3%), chemotherapy (49.7%), and PRRT and chemotherapy (22.8%). Overall, 85.2% of patients experienced adverse events (AEs), which were severe (grade 3-4) in 46.1%. The most frequent severe AEs were pneumonitis (8.3%), thrombocytopenia (7.7%), anemia (5.3%), and renal failure (3.5%). In patients previously treated with PRRT and chemotherapy, a 12-fold increased risk for severe toxicity was observed, with grade 3-4 AEs reported in 86.8% (vs. 34.3% in other patients). In addition, 63.3% of patients required temporarily everolimus discontinuation due to toxicity. Overall, 27.8% of patients died during a median follow-up of 12 months. Median progression-free survival (PFS) and overall survival (OS) were 12 months and 32 months, respectively. Similar disease control rates, PFS, and OS were reported in pNETs and non-pNETs. In the real-world setting, everolimus is safe and effective for the treatment of NETs of different origins. Higher severe toxicity occurred in patients previously treated with systemic chemotherapy and PRRT. This finding prompts caution when using this drug in pretreated patients and raises the issue of planning for everolimus before PRRT and chemotherapy in the therapeutic algorithm for advanced NETs. PMID:25117065

  9. Finding a better drug for epilepsy: The mTOR pathway as an antiepileptogenic target

    PubMed Central

    Galanopoulou, Aristea S.; Gorter, Jan A.; Cepeda, Carlos

    2012-01-01

    Summary The mTOR signaling pathway regulates cell growth, differentiation, proliferation and metabolism. Loss of function mutations in upstream regulators of mTOR have been highly associated with dysplasias, epilepsy and neurodevelopmental disorders. These include tuberous sclerosis, which is due to mutations in TSC1 or TSC2 genes, mutations in phosphatase and tensin homolog (PTEN) as in Cowden syndrome, polyhydramnios, megalencephaly, symptomatic epilepsy syndrome (PMSE) due to mutations in the STE20-related kinase adaptor alpha (STRADalpha), and neurofibromatosis type 1 attributed to neurofibromin 1 mutations. Inhibition of the mTOR pathway with rapamycin may prevent epilepsy and improve the underlying pathology in mouse models with disrupted mTOR signaling, due to PTEN or TSC mutations. However the timing and duration of its administration appear critical in defining the seizure and pathology-related outcomes. Rapamycin application in human cortical slices from patients with cortical dysplasias reduces the 4-aminopyridine induced oscillations. In the multiple-hit model of infantile spasms, pulse high dose rapamycin administration can reduce the cortical overactivation of the mTOR pathway, suppresses spasms and has disease-modifying effects by partially improving cognitive deficits. In post-status epilepticus models of temporal lobe epilepsy, rapamycin may ameliorate the development of epilepsy-related pathology and reduce the expression of spontaneous seizures, but its effects depend on the timing and duration of administration, and possibly the model used. The observed recurrence of seizures and epilepsy-related pathology after rapamycin discontinuation suggests the need for continuous administration to maintain the benefit. However, the use of pulse administration protocols may be useful in certain age-specific epilepsy syndromes, like infantile spasms, whereas repetitive pulse rapamycin protocols may suffice to sustain a long-term benefit in genetic disorders

  10. The role of mTOR signaling in the regulation of protein synthesis and muscle mass during immobilization in mice

    PubMed Central

    You, Jae-Sung; Anderson, Garrett B.; Dooley, Matthew S.; Hornberger, Troy A.

    2015-01-01

    ABSTRACT The maintenance of skeletal muscle mass contributes substantially to health and to issues associated with the quality of life. It has been well recognized that skeletal muscle mass is regulated by mechanically induced changes in protein synthesis, and that signaling by mTOR is necessary for an increase in protein synthesis and the hypertrophy that occurs in response to increased mechanical loading. However, the role of mTOR signaling in the regulation of protein synthesis and muscle mass during decreased mechanical loading remains largely undefined. In order to define the role of mTOR signaling, we employed a mouse model of hindlimb immobilization along with pharmacological, mechanical and genetic means to modulate mTOR signaling. The results first showed that immobilization induced a decrease in the global rates of protein synthesis and muscle mass. Interestingly, immobilization also induced an increase in mTOR signaling, eIF4F complex formation and cap-dependent translation. Blocking mTOR signaling during immobilization with rapamycin not only impaired the increase in eIF4F complex formation, but also augmented the decreases in global protein synthesis and muscle mass. On the other hand, stimulating immobilized muscles with isometric contractions enhanced mTOR signaling and rescued the immobilization-induced decrease in global protein synthesis through a rapamycin-sensitive mechanism that was independent of ribosome biogenesis. Unexpectedly, the effects of isometric contractions were also independent of eIF4F complex formation. Similar to isometric contractions, overexpression of Rheb in immobilized muscles enhanced mTOR signaling, cap-dependent translation and global protein synthesis, and prevented the reduction in fiber size. Therefore, we conclude that the activation of mTOR signaling is both necessary and sufficient to alleviate the decreases in protein synthesis and muscle mass that occur during immobilization. Furthermore, these results indicate

  11. The role of mTOR signaling in the regulation of protein synthesis and muscle mass during immobilization in mice.

    PubMed

    You, Jae-Sung; Anderson, Garrett B; Dooley, Matthew S; Hornberger, Troy A

    2015-09-01

    The maintenance of skeletal muscle mass contributes substantially to health and to issues associated with the quality of life. It has been well recognized that skeletal muscle mass is regulated by mechanically induced changes in protein synthesis, and that signaling by mTOR is necessary for an increase in protein synthesis and the hypertrophy that occurs in response to increased mechanical loading. However, the role of mTOR signaling in the regulation of protein synthesis and muscle mass during decreased mechanical loading remains largely undefined. In order to define the role of mTOR signaling, we employed a mouse model of hindlimb immobilization along with pharmacological, mechanical and genetic means to modulate mTOR signaling. The results first showed that immobilization induced a decrease in the global rates of protein synthesis and muscle mass. Interestingly, immobilization also induced an increase in mTOR signaling, eIF4F complex formation and cap-dependent translation. Blocking mTOR signaling during immobilization with rapamycin not only impaired the increase in eIF4F complex formation, but also augmented the decreases in global protein synthesis and muscle mass. On the other hand, stimulating immobilized muscles with isometric contractions enhanced mTOR signaling and rescued the immobilization-induced decrease in global protein synthesis through a rapamycin-sensitive mechanism that was independent of ribosome biogenesis. Unexpectedly, the effects of isometric contractions were also independent of eIF4F complex formation. Similar to isometric contractions, overexpression of Rheb in immobilized muscles enhanced mTOR signaling, cap-dependent translation and global protein synthesis, and prevented the reduction in fiber size. Therefore, we conclude that the activation of mTOR signaling is both necessary and sufficient to alleviate the decreases in protein synthesis and muscle mass that occur during immobilization. Furthermore, these results indicate that the

  12. Growth hormone abolishes the negative effects of everolimus on intestinal wound healing

    PubMed Central

    Küper, Markus Alexander; Trütschel, Sebastian; Weinreich, Jürgen; Königsrainer, Alfred; Beckert, Stefan

    2016-01-01

    AIM: To investigate whether the simultaneous treatment with human growth hormone (hGH) abolishes the negative effects of everolimus on anastomotic healing. METHODS: Forty-eight male Sprague-Dawley-rats were randomized to three groups of 16 animals each (I: vehicle; II: everolimus 3 mg/kg po; III: everolimus 3 mg/kg po + hGH 2.5 mg/kg sc). Animals were pre-treated with hGH and/or everolimus daily for seven days. Then a standard anastomosis was created in the descending colon and treatment was continued for another seven days. The anastomosis was resected in toto and the bursting pressure was assessed as a mechanical parameter of intestinal healing. Moreover, biochemical (Hydroxyproline, PCNA, MPO, MMP-2 and MMP-9) and histological (cell density, angiogenesis, amount of granulation tissue) parameters of intestinal healing were assessed. RESULTS: Anastomotic bursting pressure was significantly reduced by everolimus and a simultaneous treatment with hGH resulted in considerably higher values (I: 134 ± 19 mmHg, II: 85 ± 25 mmHg, III: 114 ± 25 mmHg; P < 0.05, I vs II; P = 0.09, I vs III and II vs III) Hydroxyproline concentration was significantly increased by hGH compared to everolimus alone (I: 14.9 ± 2.5 μg/mg, II: 8.9 ± 3.6 μg/mg, III: 11.9 ± 2.8 μg/mg; P < 0.05, I vs II/III and II vs III). The number of MPO-positive cells was reduced significantly by hGH compared to everolimus alone (I: 10 ± 1 n/mm², II: 15 ± 3 n/mm², III: 9 ± 2 n/mm²; P < 0.05, I vs II and II vs III), while the number of PCNA-positive cells were increased by hGH (I: 28 ± 3 /mm², II: 12 ± 3 /mm², III: 26 ± 12 /mm²; P < 0.05, I vs II and II vs III). Corresponding to these biochemical findings, HE-histology revealed significantly increased amount of granulation tissue in hGH-treated animals. CONCLUSION: Inhibition of intestinal wound healing by everolimus is partially neutralized by simultaeous treatment with hGH. Both inflammation as well as collagen

  13. Cardiac mTOR rescues the detrimental effects of diet-induced obesity in the heart after ischemia-reperfusion.

    PubMed

    Aoyagi, Toshinori; Higa, Jason K; Aoyagi, Hiroko; Yorichika, Naaiko; Shimada, Briana K; Matsui, Takashi

    2015-06-15

    Diet-induced obesity deteriorates the recovery of cardiac function after ischemia-reperfusion (I/R) injury. While mechanistic target of rapamycin (mTOR) is a key mediator of energy metabolism, the effects of cardiac mTOR in ischemic injury under metabolic syndrome remains undefined. Using cardiac-specific transgenic mice overexpressing mTOR (mTOR-Tg mice), we studied the effect of mTOR on cardiac function in both ex vivo and in vivo models of I/R injury in high-fat diet (HFD)-induced obese mice. mTOR-Tg and wild-type (WT) mice were fed a HFD (60% fat by calories) for 12 wk. Glucose intolerance and insulin resistance induced by the HFD were comparable between WT HFD-fed and mTOR-Tg HFD-fed mice. Functional recovery after I/R in the ex vivo Langendorff perfusion model was significantly lower in HFD-fed mice than normal chow diet-fed mice. mTOR-Tg mice demonstrated better cardiac function recovery and had less of the necrotic markers creatine kinase and lactate dehydrogenase in both feeding conditions. Additionally, mTOR overexpression suppressed expression of proinflammatory cytokines, including IL-6 and TNF-α, in both feeding conditions after I/R injury. In vivo I/R models showed that at 1 wk after I/R, HFD-fed mice exhibited worse cardiac function and larger myocardial scarring along myofibers compared with normal chow diet-fed mice. In both feeding conditions, mTOR overexpression preserved cardiac function and prevented myocardial scarring. These findings suggest that cardiac mTOR overexpression is sufficient to prevent the detrimental effects of diet-induced obesity on the heart after I/R, by reducing cardiac dysfunction and myocardial scarring.

  14. mTOR activation is a biomarker and a central pathway to autoimmune disorders, cancer, obesity, and aging

    PubMed Central

    Perl, Andras

    2015-01-01

    The mechanistic target of rapamycin (mTOR) is a ubiquitous serine/threonine kinase that plays pivotal roles in integrating growth signals on a cellular level. To support proliferation and survival under stress, two interacting complexes that harbor mTOR, mTORC1 and mTORC2, promote the transcription of genes involved in carbohydrate metabolism and lipogenesis, enhance protein translation, and inhibit autophagy. While rapamycin was originally developed as an inhibitor of T cell proliferation for preventing organ transplant rejection, its molecular target, mTOR, has been subsequently identified as a central regulator of metabolic cues that drive lineage specification in the immune system. Owing to oxidative stress, the activation of mTORC1 has emerged as a central pathway for the pathogenesis of systemic lupus erythematosus and other autoimmune diseases. Paradoxically, mTORC1 has been also identified as a mediator of the Warburg effect that allows cell survival under hypoxia. Rapamycin and new classes of mTOR inhibitors are being developed to block not only transplant rejection and autoimmunity but also to treat obesity and various forms of cancer. Through preventing these diseases, personalized mTOR blockade holds promise to extend life span. PMID:25907074

  15. mTOR activation is a biomarker and a central pathway to autoimmune disorders, cancer, obesity, and aging.

    PubMed

    Perl, Andras

    2015-06-01

    The mechanistic target of rapamycin (mTOR) is a ubiquitous serine/threonine kinase, which plays pivotal roles in integrating growth signals on a cellular level. To support proliferation and survival under stress, two interacting complexes that harbor mTOR, mTORC1 and mTORC2, promote the transcription of genes involved in carbohydrate metabolism and lipogenesis, enhance protein translation, and inhibit autophagy. Although rapamycin was originally developed as an inhibitor of T cell proliferation for preventing organ transplant rejection, its molecular target, mTOR, has been subsequently identified as a central regulator of metabolic cues that drive lineage specification in the immune system. Owing to oxidative stress, the activation of mTORC1 has emerged as a central pathway for the pathogenesis of systemic lupus erythematosus and other autoimmune diseases. Paradoxically, mTORC1 has also been identified as a mediator of the Warburg effect that allows cell survival under hypoxia. Rapamycin and new classes of mTOR inhibitors are being developed to block not only transplant rejection and autoimmunity but also to treat obesity and various forms of cancer. Through preventing these diseases, personalized mTOR blockade holds promise to extend life span.

  16. The mTOR inhibitor sirolimus suppresses renal, hepatic, and cardiac tissue cellular respiration.

    PubMed

    Albawardi, Alia; Almarzooqi, Saeeda; Saraswathiamma, Dhanya; Abdul-Kader, Hidaya Mohammed; Souid, Abdul-Kader; Alfazari, Ali S

    2015-01-01

    The purpose of this in vitro study was to develop a useful biomarker (e.g., cellular respiration, or mitochondrial O2 consumption) for measuring activities of mTOR inhibitors. It measured the effects of commonly used immunosuppressants (sirolimus-rapamycin, tacrolimus, and cyclosporine) on cellular respiration in target tissues (kidney, liver, and heart) from C57BL/6 mice. The mammalian target of rapamycin (mTOR), a serine/ threonine kinase that supports nutrient-dependent cell growth and survival, is known to control energy conversion processes within the mitochondria. Consistently, inhibitors of mTOR (e.g., rapamycin, also known as sirolimus or Rapamune®) have been shown to impair mitochondrial function. Inhibitors of the calcium-dependent serine/threonine phosphatase calcineurin (e.g., tacrolimus and cyclosporine), on the other hand, strictly prevent lymphokine production leading to a reduced T-cell function. Sirolimus (10 μM) inhibited renal (22%, P=0.002), hepatic (39%, P<0.001), and cardiac (42%, P=0.005) cellular respiration. Tacrolimus and cyclosporine had no or minimum effects on cellular respiration in these tissues. Thus, these results clearly demonstrate that impaired cellular respiration (bioenergetics) is a sensitive biomarker of the immunosuppressants that target mTOR.

  17. The role of mTOR signalling in the regulation of skeletal muscle mass in a rodent model of resistance exercise.

    PubMed

    Ogasawara, Riki; Fujita, Satoshi; Hornberger, Troy A; Kitaoka, Yu; Makanae, Yuhei; Nakazato, Koichi; Naokata, Ishii

    2016-01-01

    Resistance exercise (RE) activates signalling by the mammalian target of rapamycin (mTOR), and it has been suggested that rapamycin-sensitive mTOR signalling controls RE-induced changes in protein synthesis, ribosome biogenesis, autophagy, and the expression of peroxisome proliferator gamma coactivator 1 alpha (PGC-1α). However, direct evidence to support the aforementioned relationships is lacking. Therefore, in this study, we investigated the role of rapamycin-sensitive mTOR in the RE-induced activation of muscle protein synthesis, ribosome biogenesis, PGC-1α expression and hypertrophy. The results indicated that the inhibition of rapamycin-sensitive mTOR could prevent the induction of ribosome biogenesis by RE, but it only partially inhibited the activation of muscle protein synthesis. Likewise, the inhibition of rapamycin-sensitive mTOR only partially blocked the hypertrophic effects of chronic RE. Furthermore, both acute and chronic RE promoted an increase in PGC-1α expression and these alterations were not affected by the inhibition of rapamycin-sensitive mTOR. Combined, the results from this study not only establish that rapamycin-sensitive mTOR plays an important role in the RE-induced activation of protein synthesis and the induction of hypertrophy, but they also demonstrate that additional (rapamycin-sensitive mTOR-independent) mechanisms contribute to these fundamentally important events. PMID:27502839

  18. The role of mTOR signalling in the regulation of skeletal muscle mass in a rodent model of resistance exercise

    PubMed Central

    Ogasawara, Riki; Fujita, Satoshi; Hornberger, Troy A.; Kitaoka, Yu; Makanae, Yuhei; Nakazato, Koichi; Naokata, Ishii

    2016-01-01

    Resistance exercise (RE) activates signalling by the mammalian target of rapamycin (mTOR), and it has been suggested that rapamycin-sensitive mTOR signalling controls RE-induced changes in protein synthesis, ribosome biogenesis, autophagy, and the expression of peroxisome proliferator gamma coactivator 1 alpha (PGC-1α). However, direct evidence to support the aforementioned relationships is lacking. Therefore, in this study, we investigated the role of rapamycin-sensitive mTOR in the RE-induced activation of muscle protein synthesis, ribosome biogenesis, PGC-1α expression and hypertrophy. The results indicated that the inhibition of rapamycin-sensitive mTOR could prevent the induction of ribosome biogenesis by RE, but it only partially inhibited the activation of muscle protein synthesis. Likewise, the inhibition of rapamycin-sensitive mTOR only partially blocked the hypertrophic effects of chronic RE. Furthermore, both acute and chronic RE promoted an increase in PGC-1α expression and these alterations were not affected by the inhibition of rapamycin-sensitive mTOR. Combined, the results from this study not only establish that rapamycin-sensitive mTOR plays an important role in the RE-induced activation of protein synthesis and the induction of hypertrophy, but they also demonstrate that additional (rapamycin-sensitive mTOR-independent) mechanisms contribute to these fundamentally important events. PMID:27502839

  19. Immunoregulatory Effects of Everolimus on In Vitro Alloimmune Responses

    PubMed Central

    Levitsky, Josh; Miller, Joshua; Huang, Xuemei; Gallon, Lorenzo; Leventhal, Joseph R.; Mathew, James M.

    2016-01-01

    Everolimus (EVL) is a novel mTOR-inhibitor similar to sirolimus (SRL) that is used in organ transplant recipients, often in combination with tacrolimus (TAC) or mycophenolate (MPA). The current study aims to determine its effects on regulatory T cells. Increasing concentrations of EVL, MPA and TAC alone or in combination were added to MLRs of healthy volunteers. Lymphoproliferation by 3H-TdR incorporation and the percentage of newly generated CD4+CD127-CD25+FOXP3+ (total Treg) and CD4+CD127-CD25HighFOXP3+ (natural Treg) in CFSE labeled responder cells were assessed by flow cytometry. In comparison to medium controls, EVL and other agents dose-dependently inhibited 3H-TdR incorporation in HLA-2DR-matched and HLA-mismatched MLRs (n = 3–10). However, EVL significantly amplified newly generated total and natural Tregs in CFSE labeled responder cells (p<0.05) at all concentrations, while MPA and SRL did this only at sub-therapeutic concentrations and inhibited at therapeutic levels. In contrast, TAC inhibited newly generated Tregs at all concentrations. When tested in combination with TAC, EVL failed to reverse TAC inhibition of Treg generation. Combinations of EVL and low concentrations of MPA inhibited proliferation and amplified Treg generation in an additive manner when compared to medium controls or each drug tested alone (p<0.05). The relative tolerogenic effect from high to low was EVL > SRL> MPA > TAC. If the results from these in vitro studies are extrapolated to clinical transplantation, it would suggest EVL plus low concentrations of MPA may be the most tolerogenic combination. PMID:27275747

  20. mTOR signaling in protein homeostasis

    PubMed Central

    Conn, Crystal S

    2011-01-01

    A proper balance between synthesis, maturation and degradation of cellular proteins is crucial for cells to maintain physiological functions. The costly process of protein synthesis is tightly coupled to energy status and nutrient levels by the mammalian target of rapamycin (mTOR), whereas the quality of newly synthesized polypeptides is largely maintained by molecular chaperones and the ubiquitin-proteasome system. There is a wealth of evidence indicating close ties between the nutrient signaling pathway and the intracellular stress response. Dysregulation of both systems has been implicated in aging and age-associated pathologies. In this review, we describe molecular mechanisms underlying the connection between mTOR and the chaperone network and discuss the importance of their functional interaction in growth and aging. PMID:21555915

  1. Assessing Metabolic Changes in Response to mTOR Inhibition in a Mantle Cell Lymphoma Xenograft Model Using AcidoCEST MRI

    PubMed Central

    Akhenblit, Paul J.; Hanke, Neale T.; Gill, Alexander; Persky, Daniel O.; Howison, Christine M.; Pagel, Mark D.; Baker, Amanda F.

    2016-01-01

    AcidoCEST magnetic resonance imaging (MRI) has previously been shown to measure tumor extracellular pH (pHe) with excellent accuracy and precision. This study investigated the ability of acidoCEST MRI to monitor changes in tumor pHe in response to therapy. To perform this study, we used the Granta 519 human mantle cell lymphoma cell line, which is an aggressive B-cell malignancy that demonstrates activation of the phosphatidylinositol-3-kinase/Akt/mammalian target of rapamycin (mTOR) pathway. We performed in vitro and in vivo studies using the Granta 519 cell line to investigate the efficacy and associated changes induced by the mTOR inhibitor, everolimus (RAD001). AcidoCEST MRI studies showed a statistically significant increase in tumor pHe of 0.10 pH unit within 1 day of initiating treatment, which foreshadowed a decrease in tumor growth of the Granta 519 xenograft model. AcidoCEST MRI then measured a decrease in tumor pHe 7 days after initiating treatment, which foreshadowed a return to normal tumor growth rate. Therefore, this study is a strong example that acidoCEST MRI can be used to measure tumor pHe that may serve as a marker for therapeutic efficacy of anticancer therapies. PMID:27140422

  2. Role of mTOR1 and mTOR2 complexes in MEG-01 cell physiology.

    PubMed

    López, Esther; Berna-Erro, Alejandro; López, Javier J; Granados, María P; Bermejo, Nuria; Brull, Jose M; Salido, Ginés M; Rosado, Juan A; Redondo, Pedro C

    2015-11-01

    The function of the mammalian target of rapamycin (mTOR) is upregulated in response to cell stimulation with growing and differentiating factors. Active mTOR controls cell proliferation, differentiation and death. Since mTOR associates with different proteins to form two functional macromolecular complexes, we aimed to investigate the role of the mTOR1 and mTOR2 complexes in MEG-01 cell physiology in response to thrombopoietin (TPO). By using mTOR antagonists and overexpressing FKBP38, we have explored the role of both mTOR complexes in proliferation, apoptosis, maturation-like mechanisms, endoplasmic reticulum-stress and the intracellular location of both active mTOR complexes during MEG-01 cell stimulation with TPO. The results demonstrate that mTOR1 and mTOR2 complexes play different roles in the physiology of MEG-01 cells and in the maturation-like mechanisms; hence, these findings might help to understand the mechanism underlying generation of platelets.

  3. Combination of clopidogrel and everolimus dramatically reduced the development of transplant arteriosclerosis in murine aortic allografts.

    PubMed

    Eckl, Sebastian; Heim, Christian; Abele-Ohl, Silke; Hoffmann, Julia; Ramsperger-Gleixner, Martina; Weyand, Michael; Ensminger, Stephan M

    2010-09-01

    Our group has shown that platelet inhibition with clopidogrel, an antagonist of the P2Y12 adenosine diphosphate receptor on platelets, reduced the formation of transplant arteriosclerosis. The aim of this study was to investigate whether a combination of cyclosporin or everolimus with clopidogrel has a beneficial effect on the development of transplant arteriosclerosis. Fully MHC mismatched C57Bl/6 (H2(b)) donor aortas were transplanted into CBA.J (H2(k)) recipients and mice received either clopidogrel alone (1 mg/kg/day) or in combination with cyclosporin (2 mg/kg/day) or everolimus (0.05 mg/kg/day). Grafts were analysed by histology and morphometry on day 30 after transplantation. In mice treated with clopidogrel alone, transplant arteriosclerosis was significantly reduced [intima proliferation 56 +/- 11% vs. 81 +/- 7% (control)/n = 7]. Daily application of everolimus reduced the development of transplant arteriosclerosis compared with untreated controls [intima proliferation of 29 +/- 9% vs. 81 +/- 7% (control)/n = 7]. Strikingly, combination of clopidogrel and everolimus almost abolished the formation of transplant arteriosclerosis [intima proliferation: 11 +/- 8% vs. 81 +/- 7% (control)/n = 7]. By contrast, combination of cyclosporin and clopidogrel compared with clopidogrel alone showed no additive effect. These results demonstrate that combination of platelet- and mammalian target of Rapamycin-inhibition can dramatically reduce the development of transplant arteriosclerosis.

  4. Phase I Study of Capecitabine, Oxaliplatin, Bevacizumab, and Everolimus in Advanced Solid Tumors

    PubMed Central

    Rangwala, F.; Bendell, J.; Kozloff, M.; Arrowood, C.; Dellinger, A.; Meadows, J.; Tourt-Uhlig, S.; Murphy, J.; Meadows, K.L.; Starr, A.; Broderick, S.; Brady, J.C.; Cushman, S. M.; Morse, M.; Uronis, H.; Hsu, S.D.; Zafar, S.Y.; Wallace, J.; Starodub, A.; Strickler, J.; Pang, H.; Nixon, A.B.; Hurwitz, H.

    2014-01-01

    Purpose To define maximum tolerated dose (MTD), toxicities, and pharmacodynamics of capecitabine, oxaliplatin, bevacizumab, and everolimus in advanced solid tumor patients. Design This was a standard “3+3” dose-escalation trial. All subjects received bevacizumab 7.5mg/kg on day one of each cycle. Doses for capecitabine, oxaliplatin and everolimus were modified per dose limiting toxicity (DLT). Baseline and on-treatment plasma biomarkers were analyzed. Archived tumor mRNA levels were evaluated for NRP1, NRP2 and VEGF-A isoforms. Results Twenty-nine patients were evaluable for toxicity and 30 for efficacy. Two DLTs were observed in cohort 1 and one DLT each was observed in cohort -1 and -1b. Grade ≥3 toxicities included neutropenia, hypertension, perforation/fistula/hemorrhage, hypertriglyceridemia, diarrhea, and thromboembolism. Twelve subjects experienced partial response (PR); 12 had stable disease as best response. Three of seven chemorefractory metastatic colorectal cancer (mCRC) subjects experienced PR; eight of 15 chemonaive mCRC subjects experienced PR. Plasma TβRIII and IL-6 increased on treatment but without correlation to outcome. Increased VEGF165 levels significantly correlated with longer progression free survival. Conclusions Everolimus with full dose capecitabine, oxaliplatin, and bevacizumab had unacceptable toxicity. MTD was: everolimus 5mg daily; capecitabine 680mg/m2 BID days 1-14; oxaliplatin 100mg/m2 and bevacizumab 7.5mg/kg, day one. Activity was noted in mCRC. PMID:24711126

  5. Long-term Cross-validation of Everolimus Therapeutic Drug Monitoring Assays: The Zortracker Study

    PubMed Central

    Schniedewind, B; Niederlechner, S; Galinkin, JL; Johnson-Davis, KL; Christians, U; Meyer, EJ

    2015-01-01

    Background This ongoing academic collaboration was initiated for providing support to set up, validate, and maintain everolimus therapeutic drug monitoring (TDM) assays and to study long-term inter- laboratory performance. Methods This study was based on EDTA whole blood samples collected from transplant patients treated with everolimus in a prospective clinical trial. Samples were handled under controlled conditions during collection, storage, and were shipped on dry ice to minimize freeze-thaw cycles. For more than 1.5 years participating laboratories received a set of 3 blinded samples on a monthly basis. Among others, these samples included individual patient samples, patient sample pools to assess long-term performance and patient samples pools enriched with isolated everolimus metabolites. Results The results between LC-MS/MS and the everolimus Quantitative Microsphere System (QMS, Thermo Fisher) assay were comparable. The monthly inter-laboratory variability (CV%) for cross validation samples ranged from 6.5 – 23.2% (average of 14.8%) for LC-MS/MS and 4.2 – 26.4% (average of 11.1%) for laboratories using the QMS assay. A blinded long-term pool sample was sent to the laboratories for 13 months. The result was 5.31 ± 0.86 ng/mL (range 2.9–7.8 ng/mL) for the LC-MS/MS and 5.20 ± 0.54 ng/mL (range 4.0–6.8 ng/mL) for QMS laboratories. Conclusions Enrichment of patient sample pools with 5–25 ng/mL of purified everolimus metabolites (46-hydroxy everolimus and 39-O-desmethyl everolimus) did not affect the results of either LC-MS/MS or QMS assays. Both LC-MS/MS and QMS assays gave similar results and showed similar performance, albeit with a trend towards higher inter-laboratory variability among laboratories using LC-MS/MS than the QMS assay. PMID:25970506

  6. Everolimus for subependymal giant cell astrocytoma: 5‐year final analysis

    PubMed Central

    Agricola, Karen; Mays, Maxwell; Tudor, Cindy; Care, Marguerite M.; Holland‐Bouley, Katherine; Berkowitz, Noah; Miao, Sara; Peyrard, Séverine; Krueger, Darcy A.

    2015-01-01

    Objective To analyze the cumulative efficacy and safety of everolimus in treating subependymal giant cell astrocytomas (SEGA) associated with tuberous sclerosis complex (TSC) from an open‐label phase II study (NCT00411619). Updated data became available from the conclusion of the extension phase and are presented in this ≥5‐year analysis. Methods Patients aged ≥ 3 years with a definite diagnosis of TSC and increasing SEGA lesion size (≥2 magnetic resonance imaging scans) received everolimus starting at 3mg/m2/day (titrated to target blood trough levels of 5–15ng/ml). The primary efficacy endpoint was reduction from baseline in primary SEGA volume. Results As of the study completion date (January 28, 2014), 22 of 28 (78.6%) initially enrolled patients finished the study per protocol. Median (range) duration of exposure to everolimus was 67.8 (4.7–83.2) months; 12 (52.2%) and 14 (60.9%) of 23 patients experienced SEGA volume reductions of ≥50% and ≥30% relative to baseline, respectively, after 60 months of treatment. The proportion of patients experiencing daily seizures was reduced from 7 of 26 (26.9%) patients at baseline to 2 of 18 (11.1%) patients at month 60. Most commonly reported adverse events (AEs) were upper respiratory tract infection and stomatitis of mostly grade 1 or 2 severity. No patient discontinued treatment due to AEs. The frequency of emergence of most AEs decreased over the course of the study. Interpretation Everolimus continues to demonstrate a sustained effect on SEGA tumor reduction over ≥5 years of treatment. Everolimus remained well‐tolerated, and no new safety concerns were noted. Ann Neurol 2015;78:929–938 PMID:26381530

  7. Everolimus in combination with cyclosporin a as pre- and posttransplantation immunosuppressive therapy in nonmyeloablative allogeneic hematopoietic stem cell transplantation.

    PubMed

    Junghanss, Christian; Rathsack, Susanne; Wacke, Rainer; Weirich, Volker; Vogel, Heike; Drewelow, Bernd; Mueller, Sabrina; Altmann, Simone; Freund, Mathias; Lange, Sandra

    2012-07-01

    Everolimus (RAD001) is an mTOR inhibitor that has been successfully used as an immunosuppressant in solid-organ transplantation. Data in allogeneic hematopoietic stem cell transplantation (HSCT) is limited. This study aimed to investigate pharmacokinetics, safety, and efficacy of RAD001 in a canine allogeneic HSCT model. First, pharmacokinetics of RAD001 were performed in healthy dogs in order to determine the appropriate dosing. Doses of 0.25 mg RAD001 twice daily in combination with 15 mg/kg cyclosporin A (CsA) twice daily were identified as appropriate starting doses to achieve the targeted range of RAD001 (3-8 μg/L) when orally administered. Subsequently, 10 dogs were transplanted using 2 Gy total body irradiation (TBI) for conditioning and 0.25 mg RAD001 twice daily plus 15 mg/kg CsA twice daily for pre- and posttransplantation immunosuppression. Seven of the 10 transplanted dogs were maintained at the starting RAD001 dose throughout the study. For the remaining 3 dogs, dose adjustments were necessary. RAD001 accumulation over time did not occur. All dogs initially engrafted. Five dogs eventually rejected the graft (weeks 10, 10, 13, 27, and 56). Two dogs died of pneumonia (weeks 8 and 72) but were chimeric until then. Total cholesterol rose from median 4.1 mmol/L (3.5-5.7 mmol/L) before HSCT to 6.0 mmol/l (5.0-8.5 mmol/l) at day 21 after HSCT, but remained always within normal range. Changes in creatinine and triglyceride values were not observed. Long-term engraftment rates were inferior to sirolimus/CsA and mycophenolate mofetil (MMF)/CsA regimen, respectively. RAD001/CsA caused a more pronounced reduction of platelet counts to median 2 × 10(9)/L (range: 0-21 × 10(9)/L) and longer time to platelet recovery of 21 days (range: 14-24 days) compared with MMF/CsA. CsA c(2h) levels were significantly enhanced in the RAD001/CsA regimen, but c(0h) and area under the curve from 0 to 12 hours (AUC(0-12h)) values did not differ compared with an MMF

  8. Chronic Repression of mTOR Complex 2 Induces Changes in the Gut Microbiota of Diet-induced Obese Mice.

    PubMed

    Jung, Mi-Ja; Lee, Jina; Shin, Na-Ri; Kim, Min-Soo; Hyun, Dong-Wook; Yun, Ji-Hyun; Kim, Pil Soo; Whon, Tae Woong; Bae, Jin-Woo

    2016-01-01

    Alterations in the gut microbiota play a crucial role in host physiology and metabolism; however, the molecular pathways underlying these changes in diet-induced obesity are unclear. Mechanistic target of rapamycin (mTOR) signaling pathway is associated with metabolic disorders such as obesity and type 2 diabetes (T2D). Therefore, we examined whether changes in the regulation of mTOR signaling induced by diet (a high-fat diet [HFD] or normal-chow diet) and/or therapeutics (resveratrol [a specific inhibitor of mTOR complex 1] or rapamycin [an inhibitor of both mTOR complex 1 and 2]) altered the composition of the gut microbiota in mice. Oral administration of resveratrol prevented glucose intolerance and fat accumulation in HFD-fed mice, whereas rapamycin significantly impaired glucose tolerance and exacerbated intestinal inflammation. The abundance of Lactococcus, Clostridium XI, Oscillibacter, and Hydrogenoanaerobacterium increased under the HFD condition; however, the abundance of these species declined after resveratrol treatment. Conversely, the abundance of unclassified Marinilabiliaceae and Turicibacter decreased in response to a HFD or rapamycin. Taken together, these results demonstrated that changes in the composition of intestinal microbiota induced by changes in mTOR activity correlate with obese and diabetic phenotypes. PMID:27471110

  9. The mechanical activation of mTOR signaling: an emerging role for late endosome/lysosomal targeting.

    PubMed

    Jacobs, Brittany L; Goodman, Craig A; Hornberger, Troy A

    2014-02-01

    It is well recognized that mechanical signals play a critical role in the regulation of skeletal muscle mass, and the maintenance of muscle mass is essential for mobility, disease prevention and quality of life. Furthermore, over the last 15 years it has become established that signaling through a protein kinase called the mammalian (or mechanistic) target of rapamycin (mTOR) is essential for mechanically-induced changes in protein synthesis and muscle mass, however, the mechanism(s) via which mechanical stimuli regulate mTOR signaling have not been defined. Nonetheless, advancements are being made, and an emerging body of evidence suggests that the late endosome/lysosomal (LEL) system might play a key role in this process. Therefore, the purpose of this review is to summarize this body of evidence. Specifically, we will first explain why the Ras homologue enriched in brain (Rheb) and phosphatidic acid (PA) are considered to be direct activators of mTOR signaling. We will then describe the process of endocytosis and its involvement in the formation of LEL structures, as well as the evidence which indicates that mTOR and its direct activators (Rheb and PA) are all enriched at the LEL. Finally, we will summarize the evidence that has implicated the LEL in the regulation of mTOR by various growth regulatory inputs such as amino acids, growth factors and mechanical stimuli. PMID:24162376

  10. Chronic Repression of mTOR Complex 2 Induces Changes in the Gut Microbiota of Diet-induced Obese Mice

    PubMed Central

    Jung, Mi-Ja; Lee, Jina; Shin, Na-Ri; Kim, Min-Soo; Hyun, Dong-Wook; Yun, Ji-Hyun; Kim, Pil Soo; Whon, Tae Woong; Bae, Jin-Woo

    2016-01-01

    Alterations in the gut microbiota play a crucial role in host physiology and metabolism; however, the molecular pathways underlying these changes in diet-induced obesity are unclear. Mechanistic target of rapamycin (mTOR) signaling pathway is associated with metabolic disorders such as obesity and type 2 diabetes (T2D). Therefore, we examined whether changes in the regulation of mTOR signaling induced by diet (a high-fat diet [HFD] or normal-chow diet) and/or therapeutics (resveratrol [a specific inhibitor of mTOR complex 1] or rapamycin [an inhibitor of both mTOR complex 1 and 2]) altered the composition of the gut microbiota in mice. Oral administration of resveratrol prevented glucose intolerance and fat accumulation in HFD-fed mice, whereas rapamycin significantly impaired glucose tolerance and exacerbated intestinal inflammation. The abundance of Lactococcus, Clostridium XI, Oscillibacter, and Hydrogenoanaerobacterium increased under the HFD condition; however, the abundance of these species declined after resveratrol treatment. Conversely, the abundance of unclassified Marinilabiliaceae and Turicibacter decreased in response to a HFD or rapamycin. Taken together, these results demonstrated that changes in the composition of intestinal microbiota induced by changes in mTOR activity correlate with obese and diabetic phenotypes. PMID:27471110

  11. The mechanical activation of mTOR signaling: an emerging role for late endosome/lysosomal targeting.

    PubMed

    Jacobs, Brittany L; Goodman, Craig A; Hornberger, Troy A

    2014-02-01

    It is well recognized that mechanical signals play a critical role in the regulation of skeletal muscle mass, and the maintenance of muscle mass is essential for mobility, disease prevention and quality of life. Furthermore, over the last 15 years it has become established that signaling through a protein kinase called the mammalian (or mechanistic) target of rapamycin (mTOR) is essential for mechanically-induced changes in protein synthesis and muscle mass, however, the mechanism(s) via which mechanical stimuli regulate mTOR signaling have not been defined. Nonetheless, advancements are being made, and an emerging body of evidence suggests that the late endosome/lysosomal (LEL) system might play a key role in this process. Therefore, the purpose of this review is to summarize this body of evidence. Specifically, we will first explain why the Ras homologue enriched in brain (Rheb) and phosphatidic acid (PA) are considered to be direct activators of mTOR signaling. We will then describe the process of endocytosis and its involvement in the formation of LEL structures, as well as the evidence which indicates that mTOR and its direct activators (Rheb and PA) are all enriched at the LEL. Finally, we will summarize the evidence that has implicated the LEL in the regulation of mTOR by various growth regulatory inputs such as amino acids, growth factors and mechanical stimuli.

  12. Renal function improvement in liver transplant recipients after early everolimus conversion: A clinical practice cohort study in Spain.

    PubMed

    Bilbao, Itxarone; Salcedo, Magdalena; Gómez, Miguel Angel; Jimenez, Carlos; Castroagudín, Javier; Fabregat, Joan; Almohalla, Carolina; Herrero, Ignacio; Cuervas-Mons, Valentín; Otero, Alejandra; Rubín, Angel; Miras, Manuel; Rodrigo, Juan; Serrano, Trinidad; Crespo, Gonzalo; De la Mata, Manuel; Bustamante, Javier; Gonzalez-Dieguez, M Luisa; Moreno, Antonia; Narvaez, Isidoro; Guilera, Magda

    2015-08-01

    A national, multicenter, retrospective study was conducted to assess the results obtained for liver transplant recipients with conversion to everolimus in daily practice. The study included 477 recipients (481 transplantations). Indications for conversion to everolimus were renal dysfunction (32.6% of cases), hepatocellular carcinoma (HCC; 30.2%; prophylactic treatment for 68.9%), and de novo malignancy (29.7%). The median time from transplantation to conversion to everolimus was 68.7 months for de novo malignancy, 23.8 months for renal dysfunction, and 7.1 months for HCC and other indications. During the first year of treatment, mean everolimus trough levels were 5.4 (standard deviation [SD], 2.7) ng/mL and doses remained stable (1.5 mg/day) from the first month after conversion. An everolimus monotherapy regimen was followed by 28.5% of patients at 12 months. Patients with renal dysfunction showed a glomerular filtration rate (4-variable Modification of Diet in Renal Disease) increase of 10.9 mL (baseline mean, 45.8 [SD, 25.3] versus 57.6 [SD, 27.6] mL/minute/1.73 m(2) ) at 3 months after everolimus initiation (P < 0.001), and 6.8 mL at 12 months. Improvement in renal function was higher in patients with early conversion (<1 year). Adverse events were the primary reason for discontinuation in 11.2% of cases. The probability of survival at 3 years after conversion to everolimus was 83.0%, 71.1%, and 59.5% for the renal dysfunction, de novo malignancy, and HCC groups, respectively. Everolimus is a viable option for the treatment of renal dysfunction, and earlier conversion is associated with better recovery of renal function. Prospective studies are needed to confirm advantages in patients with malignancy.

  13. mTOR Inhibitors Alone and in Combination with JAK2 Inhibitors Effectively Inhibit Cells of Myeloproliferative Neoplasms

    PubMed Central

    Martinelli, Serena; Tozzi, Lorenzo; Guglielmelli, Paola; Bosi, Alberto; Vannucchi, Alessandro M.

    2013-01-01

    Background Dysregulated signaling of the JAK/STAT pathway is a common feature of chronic myeloproliferative neoplasms (MPN), usually associated with JAK2V617F mutation. Recent clinical trials with JAK2 inhibitors showed significant improvements in splenomegaly and constitutional symptoms in patients with myelofibrosis but meaningful molecular responses were not documented. Accordingly, there remains a need for exploring new treatment strategies of MPN. A potential additional target for treatment is represented by the PI3K/AKT/mammalian target of rapamycin (mTOR) pathway that has been found constitutively activated in MPN cells; proof-of-evidence of efficacy of the mTOR inhibitor RAD001 has been obtained recently in a Phase I/II trial in patients with myelofibrosis. The aim of the study was to characterize the effects in vitro of mTOR inhibitors, used alone and in combination with JAK2 inhibitors, against MPN cells. Findings Mouse and human JAK2V617F mutated cell lines and primary hematopoietic progenitors from MPN patients were challenged with an allosteric (RAD001) and an ATP-competitive (PP242) mTOR inhibitor and two JAK2 inhibitors (AZD1480 and ruxolitinib). mTOR inhibitors effectively reduced proliferation and colony formation of cell lines through a slowed cell division mediated by changes in cell cycle transition to the S-phase. mTOR inhibitors also impaired the proliferation and prevented colony formation from MPN hematopoietic progenitors at doses significantly lower than healthy controls. JAK2 inhibitors produced similar antiproliferative effects in MPN cell lines and primary cells but were more potent inducers of apoptosis, as also supported by differential effects on cyclinD1, PIM1 and BcLxL expression levels. Co-treatment of mTOR inhibitor with JAK2 inhibitor resulted in synergistic activity against the proliferation of JAK2V617F mutated cell lines and significantly reduced erythropoietin-independent colony growth in patients with polycythemia vera

  14. mTOR is essential for corticosteroid effects on hippocampal AMPA receptor function and fear memory.

    PubMed

    Xiong, Hui; Cassé, Frédéric; Zhou, Yang; Zhou, Ming; Xiong, Zhi-Qi; Joëls, Marian; Martin, Stéphane; Krugers, Harm J

    2015-12-01

    Glucocorticoid hormones, via activation of their receptors, promote memory consolidation, but the exact underlying mechanisms remain elusive. We examined how corticosterone regulates AMPA receptors (AMPARs), which are crucial for synaptic plasticity and memory formation. Combining a live imaging fluorescent recovery after photobleaching approach with the use of the pH-sensitive GFP-AMPAR tagging revealed that corticosterone enhances the AMPAR mobile fraction and increases synaptic trapping of AMPARs in hippocampal cells. In parallel, corticosterone-enhanced AMPAR-mediated synaptic transmission. Blocking the mammalian target of rapamycin (mTOR) pathway prevented the effects of corticosterone on both AMPAR trapping-but not on the mobile fraction-and synaptic transmission. Blocking the mTOR pathway also prevented the memory enhancing effects of corticosterone in a contextual fear-conditioning paradigm. We conclude that activation of the mTOR pathway is essential for the effects of corticosterone on synaptic trapping of AMPARs and, possibly as a consequence, fearful memory formation.

  15. Discovery – Targeted Treatments and mTOR Inhibitors

    Cancer.gov

    Thanks to discovering the anticancer effects of mTOR inhibitors, cancer treatment for pNet, a rare type of pancreatic cancer, were revolutionized. Through clinical trials, NCI continues to investigate the life-saving potential of mTOR inhibitors.

  16. Regulation of Immune Responses by mTOR

    PubMed Central

    Powell, Jonathan D.; Pollizzi, Kristen N.; Heikamp, Emily B.; Horton, Maureen R.

    2013-01-01

    mTOR is an evolutionarily conserved serine/threonine kinase that plays a central role in integrating environmental cues in the form of growth factors, amino acids, and energy. In the study of the immune system, mTOR is emerging as a critical regulator of immune function because of its role in sensing and integrating cues from the immune microenvironment. With the greater appreciation of cellular metabolism as an important regulator of immune cell function, mTOR is proving to be a vital link between immune function and metabolism. In this review, we discuss the ability of mTOR to direct the adaptive immune response. Specifically, we focus on the role of mTOR in promoting differentiation, activation, and function in T cells, B cells, and antigen-presenting cells. PMID:22136167

  17. Negative regulation of mTOR activation by diacylglycerol kinases

    PubMed Central

    Gorentla, Balachandra K.; Wan, Chi-Keung

    2011-01-01

    The engagement of TCR induces T-cell activation, which initiates multiple characteristic changes such as increase in cell size, cell division, and the production of cytokines and other effector molecules. The mammalian target of rapamycin (mTOR) regulates protein synthesis, transcription, cell survival, and autophagy. Critical roles of mTOR in T-cell activation and effector/memory differentiation have been revealed using chemical inhibitors or by genetic ablation of mTOR in T cells. However, the connection between mTOR signaling and other signaling cascades downstream of TCR is unclear. We demonstrate that diacylglycerol (DAG) and TCR engagement activate signaling in both mTOR complexes 1 and 2 through the activation of the Ras–mitogen-activated protein kinase/extracellular signal–regulated kinase 1/2 (Mek1/2)–extracellular signal–regulated kinase 1/2 (Erk1/2)–activator protein 1 (AP-1), known collectively as the Ras-Mek1/2-Erk1/2-AP-1 pathway. Deficiency of RasGRP1 or inhibition of Mek1/2 activity drastically decreases TCR-induced mTOR activation, whereas constitutively active Ras or Mek1 promotes mTOR activation. Although constitutively active Akt promotes TCR-induced mTOR activation, such activation is attenuated by Mek1/2 inhibition. We demonstrated further that DAG kinases (DGKs) α and ζ, which terminate DAG-mediated signaling, synergistically inhibit TCR-induced mTOR activation by inhibiting the Ras-Mek1/2-Erk/12 pathway. These observations provide novel insights into the regulation of mTOR activation. PMID:21310925

  18. TGF-β inhibits the activation and functions of NK cells by repressing the mTOR pathway.

    PubMed

    Viel, Sébastien; Marçais, Antoine; Guimaraes, Fernando Souza-Fonseca; Loftus, Roisin; Rabilloud, Jessica; Grau, Morgan; Degouve, Sophie; Djebali, Sophia; Sanlaville, Amélien; Charrier, Emily; Bienvenu, Jacques; Marie, Julien C; Caux, Christophe; Marvel, Jacqueline; Town, Liam; Huntington, Nicholas D; Bartholin, Laurent; Finlay, David; Smyth, Mark J; Walzer, Thierry

    2016-02-16

    Transforming growth factor-β (TGF-β) is a major immunosuppressive cytokine that maintains immune homeostasis and prevents autoimmunity through its antiproliferative and anti-inflammatory properties in various immune cell types. We provide genetic, pharmacologic, and biochemical evidence that a critical target of TGF-β signaling in mouse and human natural killer (NK) cells is the serine and threonine kinase mTOR (mammalian target of rapamycin). Treatment of mouse or human NK cells with TGF-β in vitro blocked interleukin-15 (IL-15)-induced activation of mTOR. TGF-β and the mTOR inhibitor rapamycin both reduced the metabolic activity and proliferation of NK cells and reduced the abundances of various NK cell receptors and the cytotoxic activity of NK cells. In vivo, constitutive TGF-β signaling or depletion of mTOR arrested NK cell development, whereas deletion of the TGF-β receptor subunit TGF-βRII enhanced mTOR activity and the cytotoxic activity of the NK cells in response to IL-15. Suppression of TGF-β signaling in NK cells did not affect either NK cell development or homeostasis; however, it enhanced the ability of NK cells to limit metastases in two different tumor models in mice. Together, these results suggest that the kinase mTOR is a crucial signaling integrator of pro- and anti-inflammatory cytokines in NK cells. Moreover, we propose that boosting the metabolic activity of antitumor lymphocytes could be an effective strategy to promote immune-mediated tumor suppression.

  19. mTOR expression in human testicular seminoma.

    PubMed

    Yaba, A; Bozkurt, E R; Demir, N

    2016-08-01

    The mammalian target of rapamycin (TOR) has been implicated in the control of different stressors, growth factors, nutrients and hormones, participating in the control of key cellular functions. Controlling this many pathways poses mTOR signalling as a potential new target in new treatment strategies for multiple cancer types. mTOR components could potentially mislocated in tumour cells, which could lead to activation of signalling pathway that should not be active. Therefore, we aimed to show localisation of mTOR signal proteins in testicular seminoma. Tumoural testicular tissues were obtained from 10 patients with unilateral classic seminoma undergoing to therapeutic orchidectomy and compared with control human testicular tissues. Upon immunohistochemical evaluation, we detected mTOR and p-mTOR (serine 2448), P70S6K, p-P70S6K, PKCalpha and p-PKCalpha, CD36 and MAPLC3 proteins in the cytoplasm of Sertoli cells in the seminiferous tubules. We also showed cytoplasmic perinuclear staining in seminoma cells. This study demonstrated the interaction of mTOR signalling pathway and testicular seminoma by showing intense cytoplasmic mTOR pathway proteins immunoreactivity in the seminoma, for the first time in humans. Therefore, we suggested that mTOR signalling components could create new clinical targets for treatment of testicular seminoma patients and male infertility in the future.

  20. Regulation of mTOR by mechanically induced signaling events in skeletal muscle.

    PubMed

    Hornberger, Troy Alan; Sukhija, Kunal Balu; Chien, Shu

    2006-07-01

    Mechanical stimuli play a major role in the regulation of skeletal muscle mass, and the maintenance of muscle mass contributes significantly to disease prevention and the quality of life. Although a link between mechanical stimuli and the regulation of muscle mass has been recognized for decades, the mechanisms involved in converting mechanical information into the molecular events that control this process have not been defined. Nevertheless, significant advancements are being made in this field, and it has recently been established that signaling through a rapamycin-sensitive pathway is necessary for mechanically induced growth of skeletal muscle. Since rapamycin is a highly specific inhibitor of a protein kinase called the mammalian target of rapamycin (mTOR), many investigators have concluded that mTOR signaling is necessary for the mechanically induced growth of skeletal muscle. In this review, we have summarized the current knowledge regarding how mechanical stimuli activate mTOR signaling, discussed the newly discovered role of phospholipase D (PLD) and phosphatidic acid (PA) in this pathway, and considered the potential roles of PLD and PA in the mechanical regulation of skeletal muscle mass. PMID:16855395

  1. Deregulation of mTOR signaling is involved in thymic lymphoma development in Atm-/- mice

    SciTech Connect

    Kuang, Xianghong; Shen, Jianjun; Wong, Paul K.Y.; Yan, Mingshan

    2009-06-05

    Abnormal thymocyte development with thymic lymphomagenesis inevitably occurs in Atm-/- mice, indicating that ATM plays a pivotal role in regulating postnatal thymocyte development and preventing thymic lymphomagenesis. The mechanism for ATM controls these processes is unclear. We have shown previously that c-Myc, an oncoprotein regulated by the mammalian target of rapamycin (mTOR), is overexpressed in Atm-/- thymocytes. Here, we show that inhibition of mTOR signaling with its specific inhibitor, rapamycin, suppresses normal thymocyte DNA synthesis by downregulating 4EBP1, but not S6K, and that 4EBP1 phosphorylation and cyclin D1 expression are coordinately increased in Atm-/- thymocytes. Administration of rapamycin to Atm-/- mice attenuates elevated phospho-4EBP1, c-Myc and cyclin D1 in their thymocytes, and delays thymic lymphoma development. These results indicate that mTOR downstream effector 4EBP1 is essential for normal thymocyte proliferation, but deregulation of 4EBP1 in Atm deficiency is a major factor driving thymic lymphomagenesis in the animals.

  2. Regulation of mTOR by mechanically induced signaling events in skeletal muscle.

    PubMed

    Hornberger, Troy Alan; Sukhija, Kunal Balu; Chien, Shu

    2006-07-01

    Mechanical stimuli play a major role in the regulation of skeletal muscle mass, and the maintenance of muscle mass contributes significantly to disease prevention and the quality of life. Although a link between mechanical stimuli and the regulation of muscle mass has been recognized for decades, the mechanisms involved in converting mechanical information into the molecular events that control this process have not been defined. Nevertheless, significant advancements are being made in this field, and it has recently been established that signaling through a rapamycin-sensitive pathway is necessary for mechanically induced growth of skeletal muscle. Since rapamycin is a highly specific inhibitor of a protein kinase called the mammalian target of rapamycin (mTOR), many investigators have concluded that mTOR signaling is necessary for the mechanically induced growth of skeletal muscle. In this review, we have summarized the current knowledge regarding how mechanical stimuli activate mTOR signaling, discussed the newly discovered role of phospholipase D (PLD) and phosphatidic acid (PA) in this pathway, and considered the potential roles of PLD and PA in the mechanical regulation of skeletal muscle mass.

  3. mTOR signaling in growth control and disease

    PubMed Central

    Laplante, Mathieu; Sabatini, David M.

    2012-01-01

    The mammalian target of rapamycin (mTOR) signaling pathway senses and integrates a variety of environmental cues to regulate organismal growth and homeostasis. The pathway regulates many major cellular processes and is implicated in an increasing number of pathological conditions, including cancer, obesity, type 2 diabetes, and neurodegeneration. Here, we review recent advances in our understanding of the mTOR pathway and its role in health and disease as well as aging. We further discuss pharmacological approaches to treat human pathologies linked to mTOR deregulation. PMID:22500797

  4. The MANDELA study: A multicenter, randomized, open-label, parallel group trial to refine the use of everolimus after heart transplantation.

    PubMed

    Deuse, Tobias; Bara, Christoph; Barten, Markus J; Hirt, Stephan W; Doesch, Andreas O; Knosalla, Christoph; Grinninger, Carola; Stypmann, Jörg; Garbade, Jens; Wimmer, Peter; May, Christoph; Porstner, Martina; Schulz, Uwe

    2015-11-01

    In recent years a series of trials has sought to define the optimal protocol for everolimus-based immunosuppression in heart transplantation, with the goal of minimizing exposure to calcineurin inhibitors (CNIs) and harnessing the non-immunosuppressive benefits of everolimus. Randomized studies have demonstrated that immunosuppressive potency can be maintained in heart transplant patients receiving everolimus despite marked CNI reduction, although very early CNI withdrawal may be inadvisable. A potential renal advantage has been shown for everolimus, but the optimal time for conversion and the adequate reduction in CNI exposure remain to be defined. Other reasons for use of everolimus include a substantial reduction in the risk of cytomegalovirus infection, and evidence for inhibition of cardiac allograft vasculopathy, a major cause of graft loss. The ongoing MANDELA study is a 12-month multicenter, randomized, open-label, parallel-group study in which efficacy, renal function and safety are compared in approximately 200 heart transplant patients. Patients receive CNI therapy, steroids and everolimus or mycophenolic acid during months 3 to 6 post-transplant, and are then randomized at month 6 post-transplant (i) to convert to CNI-free immunosuppression with everolimus and mycophenolic acid or (ii) to continue reduced-exposure CNI, with concomitant everolimus. Patients are then followed to month 18 post-transplant The rationale and expectations for the trial and its methodology are described herein.

  5. De novo therapy with everolimus and reduced-exposure cyclosporine following pediatric kidney transplantation: a prospective, multicenter, 12-month study.

    PubMed

    Grushkin, Carl; Mahan, John D; Mange, Kevin C; Hexham, J Mark; Ettenger, Robert

    2013-05-01

    Prospective data regarding the de novo use of everolimus following kidney transplantation in children are sparse. In a prospective, 12-month, single-arm, open-label study, pediatric kidney transplant patients received everolimus (target trough concentration ≥3 ng/mL) with reduced-exposure CsA and corticosteroids, with or without basiliximab induction. Sixteen of the 18 patients completed the study on-treatment. Age range was 2-16 yr (mean 10.9 yr); eight patients received a living donor graft. Mean (s.d.) everolimus level was 7.4 (3.1) ng/mL during the first 12 months post-transplant. There were no cases of BPAR, graft loss, or death during the study. Protocol biopsies were performed at month 12 in seven patients, with subclinical (untreated) acute rejection diagnosed in one case. Mean (s.d.) estimated GFR (Schwartz formula) was 98 (34) mL/min/1.73 m(2) at month 12. Three patients experienced one or more serious adverse events with a suspected relation to study medication. One patient discontinued study medication due to post-transplant lymphoproliferative disease (5.6%). Everolimus with reduced-dose CsA and corticosteroids achieved good efficacy and renal function and was well tolerated in this small cohort of pediatric kidney transplant patients. Controlled trials are required to answer remaining questions about the optimal use of everolimus in this setting.

  6. Phase I/II trial of everolimus in combination with bortezomib and rituximab (RVR) in relapsed/refractory Waldenstrom macroglobulinemia.

    PubMed

    Ghobrial, I M; Redd, R; Armand, P; Banwait, R; Boswell, E; Chuma, S; Huynh, D; Sacco, A; Roccaro, A M; Perilla-Glen, A; Noonan, K; MacNabb, M; Leblebjian, H; Warren, D; Henrick, P; Castillo, J J; Richardson, P G; Matous, J; Weller, E; Treon, S P

    2015-12-01

    We examined the combination of the mammalian target of rapamycin inhibitor everolimus with bortezomib and rituximab in patients with relapsed/refractory Waldenstrom macroglobulinemia (WM) in a phase I/II study. All patients received six cycles of the combination of everolimus/rituximab or everolimus/bortezomib/rituximab followed by maintenance with everolimus until progression. Forty-six patients were treated; 98% received prior rituximab and 57% received prior bortezomib. No dose-limiting toxicities were observed in the phase I. The most common treatment-related toxicities of all grades were fatigue (63%), anemia (54%), leucopenia (52%), neutropenia (48%) and diarrhea (43%). Thirty-six (78%) of the 46 patients received full dose therapy (FDT) of the three drugs. Of these 36, 2 (6%) had complete response (90% confidence interval (CI): 1-16). In all, 32/36 (89%) of patients experienced at least a minimal response (90% CI: 76-96%). The observed partial response or better response rate was 19/36 (53, 90 CI: 38-67%). For the 36 FDT patients, the median progression-free survival was 21 months (95% CI: 12-not estimable). In summary, this study demonstrates that the combination of everolimus, bortezomib and rituximab is well tolerated and achieved 89% response rate even in patients previously treated, making it a possible model of non-chemotherapeutic-based combination therapy in WM.

  7. Development of ATP-competitive mTOR Inhibitors

    PubMed Central

    Liu, Qingsong; Kang, Seong A.; Thoreen, Carson C.; Hur, Wooyoung; Wang, Jinhua; Chang, Jae Won; Markhard, Andrew; Zhang, Jianming; Sim, Taebo; Sabatini, David M.; Gray, Nathanael S.

    2014-01-01

    The mTOR mediated signaling transduction pathway has been observed to be deregulated in a wide variety of cancer and metabolic diseases. Despite extensive clinical development efforts, the well-known allosteric mTOR inhibitor rapamycin and structurally related rapalogs have failed to show significant single-agent anti-tumor efficacy in most types of cancer. This limited clinical success maybe due to the inability of the rapalogs to maintain a complete blockade mTOR mediated signaling. Therefore numerous efforts have been initiated to develop ATP-competitive mTOR inhibitors that would block both mTORC1 and mTORC2 complex activity. Here we describe our experimental approaches to develop Torin1 using a medium throughput cell-based screening assay and structure-guided drug design. PMID:22125084

  8. Three-year efficacy and safety results from a study of everolimus versus mycophenolate mofetil in de novo renal transplant patients.

    PubMed

    Vítko, Stefan; Margreiter, Raimund; Weimar, Willem; Dantal, Jacques; Kuypers, Dirk; Winkler, Michael; Øyen, Ole; Viljoen, Hendrik G; Filiptsev, Pavel; Sadek, Sami; Li, Yulan; Cretin, Nathalie; Budde, Klemens

    2005-10-01

    Everolimus 1.5 or 3 mg/day was compared with mycophenolate mofetil (MMF) 2 g/day in a randomized, multicenter 36-month trial in de novo renal allograft recipients (n = 588) receiving cyclosporine microemulsion (CsA) and corticosteroids. The study was double-blind until all patients had completed 12 months, then open-label. By 36 months, graft loss occurred in 7.2, 16.7 and 10.7% of patients in the everolimus 1.5, 3 mg/day, and MMF groups, respectively (p = 0.0048 for everolimus 1.5 mg/day vs. 3 mg/day); efficacy failure (biopsy-proven acute rejection (BPAR), graft loss, death or lost to follow-up) occurred in 33.0, 38.9 and 37.2% of patients (p = 0.455 overall), respectively. Mortality and incidence of BPAR were comparable in all groups. Creatinine values were higher in everolimus groups, requiring a protocol amendment that recommended lower CsA exposure. Diarrhea, lymphocele, peripheral edema and hyperlipidemia were more common among everolimus-treated patients, whereas viral infections, particularly cytomegalovirus infection, increased in the MMF group. Overall safety and tolerability were better with MMF and everolimus 1.5 mg/day than with everolimus 3 mg/day. In conclusion, at 36 months, an immunosuppressive regimen containing everolimus 1.5 mg/day had equivalent patient, and graft survival and rejection rates compared with MMF in de novo renal transplant recipients, whereas everolimus 3 mg/day had inferior graft survival. Renal dysfunction in everolimus cohorts necessitates close monitoring. PMID:16162203

  9. Three-year efficacy and safety results from a study of everolimus versus mycophenolate mofetil in de novo renal transplant patients.

    PubMed

    Vítko, Stefan; Margreiter, Raimund; Weimar, Willem; Dantal, Jacques; Kuypers, Dirk; Winkler, Michael; Øyen, Ole; Viljoen, Hendrik G; Filiptsev, Pavel; Sadek, Sami; Li, Yulan; Cretin, Nathalie; Budde, Klemens

    2005-10-01

    Everolimus 1.5 or 3 mg/day was compared with mycophenolate mofetil (MMF) 2 g/day in a randomized, multicenter 36-month trial in de novo renal allograft recipients (n = 588) receiving cyclosporine microemulsion (CsA) and corticosteroids. The study was double-blind until all patients had completed 12 months, then open-label. By 36 months, graft loss occurred in 7.2, 16.7 and 10.7% of patients in the everolimus 1.5, 3 mg/day, and MMF groups, respectively (p = 0.0048 for everolimus 1.5 mg/day vs. 3 mg/day); efficacy failure (biopsy-proven acute rejection (BPAR), graft loss, death or lost to follow-up) occurred in 33.0, 38.9 and 37.2% of patients (p = 0.455 overall), respectively. Mortality and incidence of BPAR were comparable in all groups. Creatinine values were higher in everolimus groups, requiring a protocol amendment that recommended lower CsA exposure. Diarrhea, lymphocele, peripheral edema and hyperlipidemia were more common among everolimus-treated patients, whereas viral infections, particularly cytomegalovirus infection, increased in the MMF group. Overall safety and tolerability were better with MMF and everolimus 1.5 mg/day than with everolimus 3 mg/day. In conclusion, at 36 months, an immunosuppressive regimen containing everolimus 1.5 mg/day had equivalent patient, and graft survival and rejection rates compared with MMF in de novo renal transplant recipients, whereas everolimus 3 mg/day had inferior graft survival. Renal dysfunction in everolimus cohorts necessitates close monitoring.

  10. Neuroprotection through excitability and mTOR required in ALS motoneurons to delay disease and extend survival.

    PubMed

    Saxena, Smita; Roselli, Francesco; Singh, Katyayani; Leptien, Kerstin; Julien, Jean-Pierre; Gros-Louis, Francois; Caroni, Pico

    2013-10-01

    Delaying clinical disease onset would greatly reduce neurodegenerative disease burden, but the mechanisms influencing early preclinical progression are poorly understood. Here, we show that in mouse models of familial motoneuron (MN) disease, SOD1 mutants specifically render vulnerable MNs dependent on endogenous neuroprotection signaling involving excitability and mammalian target of rapamycin (mTOR). The most vulnerable low-excitability FF MNs already exhibited evidence of pathology and endogenous neuroprotection recruitment early postnatally. Enhancing MN excitability promoted MN neuroprotection and reversed misfolded SOD1 (misfSOD1) accumulation and MN pathology, whereas reducing MN excitability augmented misfSOD1 accumulation and accelerated disease. Inhibiting metabotropic cholinergic signaling onto MNs reduced ER stress, but enhanced misfSOD1 accumulation and prevented mTOR activation in alpha-MNs. Modulating excitability and/or alpha-MN mTOR activity had comparable effects on the progression rates of motor dysfunction, denervation, and death. Therefore, excitability and mTOR are key endogenous neuroprotection mechanisms in motoneurons to counteract clinically important disease progression in ALS.

  11. Targeting mTOR network in colorectal cancer therapy

    PubMed Central

    Wang, Xiao-Wen; Zhang, Yan-Jie

    2014-01-01

    The mechanistic target of rapamycin (mTOR) integrates growth factor signals with cellular nutrient and energy levels and coordinates cell growth, proliferation and survival. A regulatory network with multiple feedback loops has evolved to ensure the exquisite regulation of cell growth and division. Colorectal cancer is the most intensively studied cancer because of its high incidence and mortality rate. Multiple genetic alterations are involved in colorectal carcinogenesis, including oncogenic Ras activation, phosphatidylinositol 3-kinase pathway hyperactivation, p53 mutation, and dysregulation of wnt pathway. Many oncogenic pathways activate the mTOR pathway. mTOR has emerged as an effective target for colorectal cancer therapy. In vitro and preclinical studies targeting the mTOR pathway for colorectal cancer chemotherapy have provided promising perspectives. However, the overall objective response rates in major solid tumors achieved with single-agent rapalog therapy have been modest, especially in advanced metastatic colorectal cancer. Combination regimens of mTOR inhibitor with agents such as cytotoxic chemotherapy, inhibitors of vascular endothelial growth factor, epidermal growth factor receptor and Mitogen-activated protein kinase kinase (MEK) inhibitors are being intensively studied and appear to be promising. Further understanding of the molecular mechanism in mTOR signaling network is needed to develop optimized therapeutic regimens. In this paper, oncogenic gene alterations in colorectal cancer, as well as their interaction with the mTOR pathway, are systematically summarized. The most recent preclinical and clinical anticancer therapeutic endeavors are reviewed. New players in mTOR signaling pathway, such as non-steroidal anti-inflammatory drug and metformin with therapeutic potentials are also discussed here. PMID:24764656

  12. mTOR is a Promising Therapeutic Target Both in Cisplatin-Sensitive and Cisplatin-Resistant Clear Cell Carcinoma of the Ovary

    PubMed Central

    Mabuchi, Seiji; Kawase, Chiaki; Altomare, Deborah A.; Morishige, Kenichirou; Sawada, Kenjiro; Hayashi, Masami; Tsujimoto, Masahiko; Yamoto, Mareo; Klein-Szanto, Andres J.; Schilder, Russell J.; Ohmichi, Masahide; Testa, Joseph R.; Kimura, Tadashi

    2009-01-01

    Translational Relevance Clear cell carcinoma (CCC) of the ovary is a distinctive subtype of epithelial ovarian cancer associated with a poorer sensitivity to platinum-based chemotherapy and a worse prognosis than the more common serous adenocarcinoma (SAC). To improve survival, the development of new treatment strategies that target CCC more effectively is necessary. Our results show that mTOR is more frequently activated in CCCs than in SACs. Our data have relevance for the design of future clinical studies of first-line treatment for patients with CCC of the ovary. Moreover, the finding of increased expression of phospho-mTOR and greater sensitivity to RAD001 in cisplatin-resistant CCC cells than in cisplatin-sensitive cells suggests a novel treatment option for patients with recurrent disease after cisplatin-based first-line chemotherapy. Purpose mTOR (mammalian target of rapamycin) plays a central role in cell proliferation and is regarded as a promising target in cancer therapy including for ovarian cancer. This study aims to examine the role of mTOR as a therapeutic target in clear cell carcinoma (CCC) of the ovary which is regarded as aggressive, chemo-resistant histological subtype. Experimental Design Using tissue microarrays of 98 primary ovarian cancers (52 clear cell carcinomas and 46 serous adenocarcinomas), the expression of phospho-mTOR was assessed by immunohistochemistry. Then, the growth-inhibitory effect of mTOR inhibition by RAD001 (everolimus) was examined using 2 pairs of cisplatin-sensitive parental (RMG1 and KOC7C) and cisplatin-resistant human CCC cell lines (RMG1-CR and KOC7C-CR) both in vitro and in vivo. Results Immunohistochemical analysis demonstrated mTOR was more frequently activated in CCCs than in serous adenocarcinomas (86.6% vs 50%). Treatment with RAD001 markedly inhibited the growth of both RMG1 and KOC7C cells both in vitro and in vivo. Increased expression of phospho-mTOR was observed in cisplatin-resistant RMG1-CR and KOC7C

  13. Resveratrol inhibits mTOR signaling by targeting DEPTOR

    PubMed Central

    Liu, Feng

    2011-01-01

    Resveratrol (RSV, trans-3,4,5-Trihydroxystilbene), a type of polyphenol originally found in red wines, shows a great promise for the treatment of cancer, aging, type 2 diabetes and cardiovascular diseases. Recent studies suggest that suppressing the signaling pathway mediated by mTOR, a well-known energy sensor that integrates various hormonal, nutrient and environmental signals to regulate cell growth, metabolism and survival, could play an important role in mediating the beneficial effect of RSV. The underlying mechanisms by which RSV inhibits mTOR signaling remain elusive, but our recent studies show that RSV inhibits amino acid-stimulated mTOR signaling in C2C12 fibroblasts via a Sirt1- and AMPK-independent mechanism. RSV treatment has no effect on the expression levels of mTOR, raptor and DEPTOR, but greatly promotes the interaction between mTOR and its inhibitor DEPTOR. Our results reveal a novel mechanism by which RSV inhibits mTOR signaling and its function. PMID:21966552

  14. mTOR kinase inhibitors as potential cancer therapeutic drugs

    PubMed Central

    Sun, Shi-Yong

    2013-01-01

    The mammalian target of rapamycin (mTOR) plays a critical role in the positive regulation of cell growth and survival primarily through direct interaction with raptor (forming mTORC complex 1; mTORC1) or rictor (forming mTOR complex 2; mTORC2). The mTOR axis is often activated in many types of cancer and thus has become an attractive cancer therapeutic target. The modest clinical anticancer activity of conventional mTOR allosteric inhibitors, rapamycin and its analogues (rapalogs), which preferentially inhibit mTORC1, in most types of cancer, has encouraged great efforts to develop mTOR kinase inhibitors (TORKinibs) that inhibit both mTORC1 and mTORC2, in the hope of developing a novel generation of mTOR inhibitors with better therapeutic efficacy than rapalogs. Several TORKinibs have been developed and actively studied preclinically and clinically. This review will highlight recent advances in the development and research of TORKinibs and discuss some potential issues or challenges in this area. PMID:23792225

  15. Evodiamine Inhibits Insulin-Stimulated mTOR-S6K Activation and IRS1 Serine Phosphorylation in Adipocytes and Improves Glucose Tolerance in Obese/Diabetic Mice

    PubMed Central

    Wang, Ting; Kusudo, Tatsuya; Takeuchi, Tamaki; Yamashita, Yukari; Kontani, Yasuhide; Okamatsu, Yuko; Saito, Masayuki; Mori, Nozomu; Yamashita, Hitoshi

    2013-01-01

    Evodiamine, an alkaloid extracted from the dried unripe fruit of the tree Evodia rutaecarpa Bentham (Rutaceae), reduces obesity and insulin resistance in obese/diabetic mice; however, the mechanism underlying the effect of evodiamine on insulin resistance is unknown. This study investigated the effect of evodiamine on signal transduction relating to insulin resistance using obese/diabetic KK-Ay mice and an in vitro adipocyte culture. There is a significant decrease in the mammalian target of rapamycin (mTOR) and ribosomal S6 protein kinase (S6K) signaling in white adipose tissue (WAT) in KK-Ay mice treated with evodiamine, in which glucose tolerance is improved. In addition, reduction of insulin receptor substrate 1 (IRS1) serine phosphorylation, an indicator of insulin resistance, was detected in their WAT, suggesting suppression of the negative feedback loop from S6K to IRS1. As well as the stimulation of IRS1 and Akt serine phosphorylation, insulin-stimulated phosphorylation of mTOR and S6K is time-dependent in 3T3-L1 adipocytes, whereas evodiamine does not affect their phosphorylation except for an inhibitory effect on mTOR phosphorylation. Moreover, evodiamine inhibits the insulin-stimulated phosphorylation of mTOR and S6K, leading to down-regulation of IRS1 serine phosphorylation in the adipocytes. Evodiamine also stimulates phosphorylation of AMP-activated protein kinase (AMPK), an important regulator of energy metabolism, which may cause down-regulation of mTOR signaling in adipocytes. A similar effect on AMPK, mTOR and IRS1 phosphorylation was found in adipocytes treated with rosiglitazone. These results suggest evodiamine improves glucose tolerance and prevents the progress of insulin resistance associated with obese/diabetic states, at least in part, through inhibition of mTOR-S6K signaling and IRS1 serine phosphorylation in adipocytes. PMID:24391749

  16. mTOR drives its own activation via SCFβ-TRCP-dependent degradation of the mTOR inhibitor DEPTOR

    PubMed Central

    Gao, Daming; Inuzuka, Hiroyuki; Tan, Meng-Kwang Marcus; Fukushima, Hidefumi; Locasale, Jason W.; Liu, Pengda; Wan, Lixin; Zhai, Bo; Chin, Y. Rebecca; Shaik, Shavali; Lyssiotis, Costas A.; Gygi, Steven P.; Toker, Alex; Cantley, Lewis C.; Asara, John M.; Harper, J. Wade; Wei, Wenyi

    2011-01-01

    Summary The activities of both mTORC1 and mTORC2 are negatively regulated by their endogenous inhibitor, DEPTOR. As such, the abundance of DEPTOR is a critical determinant in the activity status of the mTOR network. DEPTOR stability is governed by the 26S-proteasome through a largely unknown mechanism. Here we describe an mTOR-dependent phosphorylation-driven pathway for DEPTOR destruction via SCFβ-TRCP. DEPTOR phosphorylation by mTOR in response to growth signals, and in collaboration with casein kinase I (CKI), generates a phosphodegron that binds β-TRCP. Failure to degrade DEPTOR through either degron mutation or β-TRCP depletion leads to reduced mTOR activity, reduced S6 kinase activity, and activation of autophagy to reduce cell growth. This work expands the current understanding of mTOR regulation by revealing a positive feedback loop involving mTOR and CKI-dependent turnover of its inhibitor, DEPTOR, suggesting that misregulation of the DEPTOR destruction pathway might contribute to aberrant activation of mTOR in disease. PMID:22017875

  17. ATP-competitive inhibitors of mTOR: an update.

    PubMed

    Schenone, S; Brullo, C; Musumeci, F; Radi, M; Botta, M

    2011-01-01

    mTOR (mammalian target of rapamycin) is a serine-threonine kinase belonging to the PI3K/Akt/mTOR signalling pathway that is involved in several cell functions, including growth, proliferation, apoptosis and autophagy. mTOR hyperactivation has been detected in several human cancers, thus representing, together with its upstream effectors, an important target for cancer therapy. mTOR exists in two different complexes in cells, mTORC1 and mTORC2 which could both be targeted by potential anticancer agents. Rapamycin, the selective and allosteric inhibitor of mTOR, inhibits the enzyme in mTORC1, but not in mTORC2. In the last few years a number of mTOR ATP-competitive inhibitors has been reported acting on mTOR in both complexes and possessing a more complete anticancer activity in comparison with that of rapamycin and its derivatives. mTOR shares high sequence homology in the hinge-region with PI3K that is a lipid kinase upstream to mTOR in the same signaling pathway; for this reason some compounds originally developed as PI3K inhibitors later showed to also target mTOR. As indicated by preclinical and clinical studies, compounds acting on more than one target could result in a better biological response and in enhanced therapeutic potential and also dual PI3K/mTOR inhibitors result of great interest as potential antitumor agents. This review mainly reports the recently discovered mTOR ATP-competitive inhibitors in terms of medicinal chemistry, classified by their chemical structures, focusing on SAR and modelling studies that led to the discovery of very potent and selective agents, such as AZD-8055, OSI-027 and INK128, already entered clinical trials, or WYE-132, Torin1 and others in preclinical studies. Also some examples of dual PI3K/mTOR inhibitors, including PI-103, GNE477, WJD008 and GSK2126458 are reported together with their biological and clinical data.

  18. Prevention

    MedlinePlus

    ... our e-newsletter! Aging & Health A to Z Prevention Basic Facts & Information Some factors that affect your ... control of the things that you can change. Preventive Recommendations for Adults Aged 65 and Older The ...

  19. Talks about TORCs: recent advancesin target of rapamycin signalling. On mTOR nomenclature.

    PubMed

    Hall, Michael N

    2013-08-01

    In the present article, I discuss recent developments in the naming of the TOR (target of rapamycin) protein. In particular, I address the issue of mammalian target of rapamycin (mTOR) versus the newer mechanistic target of rapamycin (MTOR). mTOR is the name given by the TOR community almost two decades ago and widely used ever since. MTOR is a name recently imposed on the TOR community by database curators and used mainly by newcomers. I argue that MTOR is causing needless confusion in the field, and conclude that one should use the name mTOR. PMID:23863150

  20. Talks about TORCs: recent advancesin target of rapamycin signalling. On mTOR nomenclature.

    PubMed

    Hall, Michael N

    2013-08-01

    In the present article, I discuss recent developments in the naming of the TOR (target of rapamycin) protein. In particular, I address the issue of mammalian target of rapamycin (mTOR) versus the newer mechanistic target of rapamycin (MTOR). mTOR is the name given by the TOR community almost two decades ago and widely used ever since. MTOR is a name recently imposed on the TOR community by database curators and used mainly by newcomers. I argue that MTOR is causing needless confusion in the field, and conclude that one should use the name mTOR.

  1. Circulating biomarkers and outcome from a randomised phase II trial of sunitinib vs everolimus for patients with metastatic renal cell carcinoma

    PubMed Central

    Voss, Martin H; Chen, David; Marker, Mahtab; Hakimi, A Ari; Lee, Chung-Han; Hsieh, James J; Knox, Jennifer J; Voi, Maurizio; Motzer, Robert J

    2016-01-01

    Background: RECORD-3 assessed non-inferiority of progression-free survival (PFS) with everolimus vs sunitinib in previously untreated patients with metastatic renal cell carcinoma. Baseline plasma sample collection and randomised design enabled correlation of circulating biomarkers with efficacy. Methods: Samples were analysed for 121 cancer-related biomarkers. Analyses of biomarkers categorised patients as high or low (vs median) to assess association with first-line PFS (PFS1L) for each treatment arm. A composite biomarker score (CBS) incorporated biomarkers potentially predictive of PFS1L with everolimus. Results: Plasma samples from 442 of the 471 randomised patients were analysed. Biomarkers were associated with PFS1L for everolimus alone (29), sunitinib alone (9) or both (12). Everolimus-specific biomarkers (CSF1, ICAM1, IL-18BP, KIM1, TNFRII) with hazard ratio ⩾1.8 were integrated into a CBS (range 0–5). For CBS low (0–3, n=291) vs high (4–5, n=151), PFS1L differed significantly for everolimus but not for sunitinib. There was no significant difference in PFS1L between everolimus and sunitinib in the high CBS patient cohort. Conclusions: Baseline levels of multiple soluble biomarkers correlated with benefit from everolimus and/or sunitinib, independent of clinical risk factors. A similar PFS1L was observed for both treatments among patients with high CBS score. PMID:26908330

  2. Toll-like receptor 9 agonist IMO cooperates with everolimus in renal cell carcinoma by interfering with tumour growth and angiogenesis

    PubMed Central

    Damiano, V; Rosa, R; Formisano, L; Nappi, L; Gelardi, T; Marciano, R; Cozzolino, I; Troncone, G; Agrawal, S; Veneziani, B M; De Placido, S; Bianco, R; Tortora, G

    2013-01-01

    Background: Targeting the mammalian target of rapamycin by everolimus is a successful approach for renal cell carcinoma (RCC) therapy. The Toll-like receptor 9 agonist immune modulatory oligonucleotide (IMO) exhibits direct antitumour and antiangiogenic activity and cooperates with both epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) inhibitors. Methods: We tested the combination of IMO and everolimus on models of human RCC with different Von-Hippel Lindau (VHL) gene status, both in vitro and in nude mice. We studied their direct antiangiogenic effects on human umbilical vein endothelial cells. Results: Both IMO and everolimus inhibited in vitro growth and survival of RCC cell lines, and their combination produced a synergistic inhibitory effect. Moreover, everolimus plus IMO interfered with EGFR-dependent signaling and reduced VEGF secretion in both VHL wild-type and mutant cells. In RCC tumour xenografts, IMO plus everolimus caused a potent and long-lasting cooperative antitumour activity, with reduction of tumour growth, prolongation of mice survival and inhibition of signal transduction. Furthermore, IMO and everolimus impaired the main endothelial cell functions. Conclusion: A combined treatment with everolimus and IMO is effective in VHL wild-type and mutant models of RCC by interfering with tumour growth and angiogenesis, thus representing a potentially effective, rationale-based combination to be translated in the clinical setting. PMID:23571736

  3. mTOR inhibition improves immune function in the elderly.

    PubMed

    Mannick, Joan B; Del Giudice, Giuseppe; Lattanzi, Maria; Valiante, Nicholas M; Praestgaard, Jens; Huang, Baisong; Lonetto, Michael A; Maecker, Holden T; Kovarik, John; Carson, Simon; Glass, David J; Klickstein, Lloyd B

    2014-12-24

    Inhibition of the mammalian target of rapamycin (mTOR) pathway extends life span in all species studied to date, and in mice delays the onset of age-related diseases and comorbidities. However, it is unknown if mTOR inhibition affects aging or its consequences in humans. To begin to assess the effects of mTOR inhibition on human aging-related conditions, we evaluated whether the mTOR inhibitor RAD001 ameliorated immunosenescence (the decline in immune function during aging) in elderly volunteers, as assessed by their response to influenza vaccination. RAD001 enhanced the response to the influenza vaccine by about 20% at doses that were relatively well tolerated. RAD001 also reduced the percentage of CD4 and CD8 T lymphocytes expressing the programmed death-1 (PD-1) receptor, which inhibits T cell signaling and is more highly expressed with age. These results raise the possibility that mTOR inhibition may have beneficial effects on immunosenescence in the elderly.

  4. The Involvement of Mutual Inhibition of ERK and mTOR in PLCγ1-Mediated MMP-13 Expression in Human Osteoarthritis Chondrocytes.

    PubMed

    Liu, Zejun; Cai, Heguo; Zheng, Xinpeng; Zhang, Bing; Xia, Chun

    2015-01-01

    The issue of whether ERK activation determines matrix synthesis or degradation in osteoarthritis (OA) pathogenesis currently remains controversial. Our previous study shows that PLCγ1 and mTOR are involved in the matrix metabolism of OA cartilage. Investigating the interplays of PLCγ1, mTOR and ERK in matrix degradation of OA will facilitate future attempts to manipulate ERK in OA prevention and therapy. Here, cultured human normal chondrocytes and OA chondrocytes were treated with different inhibitors or transfected with expression vectors, respectively. The levels of ERK, p-ERK, PLCγ1, p-PLCγ1, mTOR, p-mTOR and MMP-13 were then evaluated by Western blotting analysis. The results manifested that the expression level of ERK in human OA chondrocytes was lower than that in human normal articular chondrocytes, and the up-regulation of ERK could promote matrix synthesis, including the decrease in MMP-13 level and the increase in Aggrecan level in human OA chondrocytes. Furthermore, the PLCγ1/ERK axis and a mutual inhibition of mTOR and ERK were observed in human OA chondrocytes. Interestingly, activated ERK had no inhibitory effect on MMP-13 expression in PLCγ1-transformed OA chondrocytes. Combined with our previous study, the non-effective state of ERK activation by PLCγ1 on MMP-13 may be partly attributed to the inhibition of the PLCγ1/mTOR axis on the PLCγ1/ERK axis. Therefore, the study indicates that the mutual inhibition of ERK and mTOR is involved in PLCγ1-mediated MMP-13 expression in human OA chondrocytes, with important implication for the understanding of OA pathogenesis as well as for its prevention and therapy.

  5. Development and Validation of Stability-indicating High Performance Liquid Chromatographic Method for the Estimation of Everolimus in Tablets.

    PubMed

    Sharmila, D; Rao, A Lakshmana; Kalyani, L

    2015-01-01

    The present study depicts the development of a validated reversed-phase high performance liquid chromatographic method for the determination of the everolimus in presence of degradation products or pharmaceutical excipients. Stress study was performed on everolimus and it was found that it degrade sufficiently in oxidizing and acidic conditions but less degradation was found in alkaline, neutral, thermal and photolytic conditions. The separation was carried out on Hypersil BDS C18 column (100×4.6 mm, 5 μ) column having particle size 5 μ using acetate buffer:acetonitrile (50:50 v/v) with pH 6.5 adjusted with orthophosphoric acid as mobile phase at flow rate of 1 ml/min. The wavelength of the detection was 280 nm. A retention time (Rt) nearly 3.110 min was observed. The calibration curve for everolimus was linear (r(2)=0.999) from range of 25-150 μg/ml with limit of detection and limit of quantification of 0.036 μg/ml and 0.109 μg/ml, respectively. Analytical validation parameters such as selectivity, specificity, linearity, accuracy and precision were evaluated and relative standard deviation value for all the key parameters were less than 2.0%. The recovery of the drug after standard addition was found to be 100.55%. Thus, the developed RP-HPLC method was found to be suitable for the determination of everolimus in tablets containing various excipients. PMID:26798176

  6. Targeting mTOR in Pancreatic Ductal Adenocarcinoma

    PubMed Central

    Iriana, Sentia; Ahmed, Shahzad; Gong, Jun; Annamalai, Alagappan Anand; Tuli, Richard; Hendifar, Andrew Eugene

    2016-01-01

    Treatment options for advanced pancreatic ductal adenocarcinoma (PDAC) are limited; however, new therapies targeting specific tumor-related molecular characteristics may help certain patient cohorts. Emerging preclinical data have shown that inhibition of mammalian target of rapamycin (mTOR) in specific KRAS-dependent PDAC subtypes leads to inhibition of tumorigenesis in vitro and in vivo. Early phase II studies of mono-mTOR inhibition have not shown promise. However, studies have shown that combined inhibition of multiple steps along the mTOR signaling pathway may lead to sustained responses by targeting mechanisms of tumor resistance. Coordinated inhibition of mTOR along with specific KRAS-dependent mutations in molecularly defined PDAC subpopulations may offer a viable alternative for treatment in the future. PMID:27200288

  7. A phase I/II trial of BNC105P with everolimus in metastatic renal cell carcinoma (mRCC)

    PubMed Central

    Pal, Sumanta; Azad, Arun; Bhatia, Shailender; Drabkin, Harry; Costello, Brian; Sarantopoulos, John; Kanesvaran, Ravindran; Lauer, Richard; Starodub, Alexander; Hauke, Ralph; Sweeney, Christopher J.; Hahn, Noah M.; Sonpavde, Guru; Richey, Stephen; Breen, Timothy; Kremmidiotis, Gabriel; Leske, Annabell; Doolin, Elizabeth; Bibby, David C.; Simpson, Jeremy; Iglesias, Jose; Hutson, Thomas

    2015-01-01

    Purpose BNC105P inhibits tubulin polymerization, and preclinical studies suggest possible synergy with everolimus. In this phase I/II study, efficacy and safety of the combination were explored in patients with metastatic renal cell carcinoma (mRCC). Experimental Design A phase I study in patients with clear cell mRCC and any prior number of therapies was conducted using a classical 3+3 design to evaluate standard doses of everolimus with increasing doses of BNC105P. At the recommended phase II dose (RP2D), patients with clear cell mRCC and 1-2 prior therapies (including ≥1 VEGF-TKI) were randomized to BNC105P with everolimus (Arm A) or everolimus alone (Arm B). The primary endpoint of the study was 6-month progression-free survival (6MPFS). Secondary endpoints included response rate, PFS, overall survival (OS) and exploratory biomarker analyses. Results In the phase I study (n=15), a dose of BNC105P at 16 mg/m2 with everolimus at 10 mg daily was identified as the RP2D. In the phase II study, 139 patients were randomized, with 69 and 67 evaluable patients in Arms A and B, respectively. 6MPFS was similar in the treatment arms (Arm A: 33.82% v Arm B: 30.30%, P=0.66) and no difference in median PFS was observed (Arm A: 4.7 mos v Arm B: 4.1 mos; P=0.49). Changes in matrix metalloproteinase-9, stem cell factor, sex hormone binding globulin and serum amyloid A protein were associated with clinical outcome with BNC105P. Conclusions Although the primary endpoint was not met in an unselected population, correlative studies suggest several biomarkers that warrant further prospective evaluation. PMID:25788492

  8. A Recollection of mTOR Signaling in Learning and Memory

    ERIC Educational Resources Information Center

    Graber, Tyson E.; McCamphill, Patrick K.; Sossin, Wayne S.

    2013-01-01

    Mechanistic target of rapamcyin (mTOR) is a central player in cell growth throughout the organism. However, mTOR takes on an additional, more specialized role in the developed neuron, where it regulates the protein synthesis-dependent, plastic changes underlying learning and memory. mTOR is sequestered in two multiprotein complexes (mTORC1 and…

  9. Prevention

    MedlinePlus

    ... Prevention Treatment 2003 U.S. Outbreak African Rodent Importation Ban For Clinicians Clinical Recognition Specimen Collection Treatment Smallpox ... Examining Animals with Suspected Monkeypox African Rodent Importation Ban Resources Related Links Poxvirus Molluscum Contagiosum Orf Virus ( ...

  10. Activation of mTOR signaling leads to orthopedic surgery-induced cognitive decline in mice through β-amyloid accumulation and tau phosphorylation.

    PubMed

    Shen, Wenzhen; Lu, Keliang; Wang, Jiawan; Wu, Anshi; Yue, Yun

    2016-10-01

    Postoperative cognitive dysfunction (POCD) is a serious complication following surgery, however, the mechanism of POCD remains to be elucidated. Previous evidence has revealed that POCD may be associated with the pathogenesis of neurodegenerative processes. The mammalian target of rapamycin (mTOR) signaling pathway has been reported to be crucial in the pathophysiology of neurodegenerative diseases. However, the implications of mTOR in POCD remains to be fully elucidated. In the present study, western blotting and enzyme‑linked immunosorbent assay were used to determine the expression of mTOR and any associated downstream targets; contextual fear conditioning was used to estimate the learning and memory ability of mice. Using an animal model of orthopedic surgery, it was found that surgical injury impaired hippocampal‑dependent memory and enhanced the levels of phosphorylated mTOR at Serine‑2448, phosphorylated 70‑kDa ribosomal protein S6 kinase (p70S6K) at Threonine‑389 with accumulation of β‑amyloid (Aβ) and hyperphosphorylated tau at Serine-396, compared with the control group. Pretreatment with rapamycin, an mTOR inhibitor, restored the abnormal mTOR/p70S6K signaling induced by surgery, attenuated the accumulation of Aβ and reduced the phosphorylation of tau protein. Rapamycin also reversed the surgery‑induced cognitive dysfunction. The results of the present study suggested that the surgical stimulus activated mTOR/p70S6K signaling excessively, and that the inhibition of mTOR signaling with rapamycin may prevent postoperative cognitive deficits, partly through attenuating the accumulation of Aβ and hyperphosphorylation of tau protein. PMID:27599409

  11. Leptin and mTOR: partners in metabolism and inflammation.

    PubMed

    Maya-Monteiro, Clarissa M; Bozza, Patricia T

    2008-06-15

    Leptin is both a hormone/cytokine that plays a major role in the regulation of feeding and energy expenditure. Beyond its central role in the hypothalamus, leptin modulates peripheral tissues' responses to growth and storage based on nutrient availability, and it regulates the innate and adaptive immune responses. mTOR (mammalian Target of Rapamycin) is a core component of intracellular signaling for cellular growth, mRNA translation, and metabolism. Here, we review recent findings on the cross talk between mTOR and leptin signaling. Important roles for mTOR on leptin signaling have been established both in hypothalamic centers to control food intake and in peripheral cells to regulate lipid metabolism and inflammation. Leptin directly activates resident macrophages to form ADRP-enriched lipid droplets and enhances eicosanoid production via a mechanism that is dependent on activation of the PI3K/mTOR pathway. Leptin-induced mTOR activation may have implications for obesity-related pathophysiological conditions such as diabetes, cardiovascular disease and cancer. PMID:18583936

  12. SYK Regulates mTOR Signaling in AML

    PubMed Central

    Carnevale, Julia; Ross, Linda; Puissant, Alexandre; Banerji, Versha; Stone, Richard M.; DeAngelo, Daniel J.; Ross, Kenneth N.; Stegmaier, Kimberly

    2014-01-01

    Spleen Tyrosine Kinase (SYK) was recently identified as a new target in acute myeloid leukemia (AML); however, its mechanistic role in this disease is poorly understood. Based on the known interaction between SYK and mTOR signaling in lymphoma, we hypothesized that SYK may regulate mTOR signaling in AML. Both small-molecule inhibition of SYK and SYK-directed shRNA suppressed mTOR and its downstream signaling effectors, as well as its upstream activator, AKT. Moreover, the inhibition of multiple nodes of the PI3K signaling pathway enhanced the effects of SYK suppression on AML cell viability and differentiation. Evaluation of the collateral MAPK pathway revealed a heterogeneous response to SYK inhibition in AML with down-regulation of MEK and ERK phosphorylation in some AML cell lines but a paradoxical increase in MEK/ERK phosphorylation in RAS-mutated AML. These studies reveal SYK as a regulator of mTOR and MAPK signaling in AML and demonstrate that inhibition of PI3K pathway activity enhances the effects of SYK inhibition on AML cell viability and differentiation. PMID:23535559

  13. mTOR in Brain Physiology and Pathologies.

    PubMed

    Bockaert, Joël; Marin, Philippe

    2015-10-01

    TOR (target of rapamycin) and its mammalian ortholog mTOR have been discovered in an effort to understand the mechanisms of action of the immunosuppressant drug rapamycin extracted from a bacterium of the Easter Island (Rapa Nui) soil. mTOR is a serine/threonine kinase found in two functionally distinct complexes, mTORC1 and mTORC2, which are differentially regulated by a great number of nutrients such as glucose and amino acids, energy (oxygen and ATP/AMP content), growth factors, hormones, and neurotransmitters. mTOR controls many basic cellular functions such as protein synthesis, energy metabolism, cell size, lipid metabolism, autophagy, mitochondria, and lysosome biogenesis. In addition, mTOR-controlled signaling pathways regulate many integrated physiological functions of the nervous system including neuronal development, synaptic plasticity, memory storage, and cognition. Thus it is not surprising that deregulation of mTOR signaling is associated with many neurological and psychiatric disorders. Preclinical and preliminary clinical studies indicate that inhibition of mTORC1 can be beneficial for some pathological conditions such as epilepsy, cognitive impairment, and brain tumors, whereas stimulation of mTORC1 (direct or indirect) can be beneficial for other pathologies such as depression or axonal growth and regeneration. PMID:26269525

  14. Molecular mechanisms of mTOR regulation by stress

    PubMed Central

    Heberle, Alexander Martin; Prentzell, Mirja Tamara; van Eunen, Karen; Bakker, Barbara Marleen; Grellscheid, Sushma Nagaraja; Thedieck, Kathrin

    2015-01-01

    Tumors are prime examples of cell growth in unfavorable environments that elicit cellular stress. The high metabolic demand and insufficient vascularization of tumors cause a deficiency of oxygen and nutrients. Oncogenic mutations map to signaling events via mammalian target of rapamycin (mTOR), metabolic pathways, and mitochondrial function. These alterations have been linked with cellular stresses, in particular endoplasmic reticulum (ER) stress, hypoxia, and oxidative stress. Yet tumors survive these challenges and acquire highly energy-demanding traits, such as overgrowth and invasiveness. In this review we focus on stresses that occur in cancer cells and discuss them in the context of mTOR signaling. Of note, many tumor traits require mTOR complex 1 (mTORC1) activity, but mTORC1 hyperactivation eventually sensitizes cells to apoptosis. Thus, mTORC1 activity needs to be balanced in cancer cells. We provide an overview of the mechanisms contributing to mTOR regulation by stress and suggest a model wherein stress granules function as guardians of mTORC1 signaling, allowing cancer cells to escape stress-induced cell death. PMID:27308421

  15. Immunosuppressive minimization with mTOR inhibitors and belatacept.

    PubMed

    Diekmann, Fritz

    2015-08-01

    Immunosuppressive therapy after kidney transplantation consists of a calcineurin inhibitor (CNI)-based therapy in combination with mycophenolic acid and steroids in most cases. In spite of low acute rejection rates and excellent graft survival, it is associated with major long-term complications, such as cardiovascular events, malignancy, and nephrotoxicity, and does not favor tolerogenic processes. Mammalian target of rapamycin (mTOR) inhibitors in combination with low-dose CNI offer good rejection rates and acceptable allograft function; however, de novo mTOR inhitibor-based treatment in combination with mycophenolate is not widely used due to higher acute rejection rates. Early conversion from a CNI to an mTOR inhibitor is a feasible option in selected patients with a slightly higher acute rejection rate, but equal or better GFR. Costimulation blockade has been proven to facilitate antirejection prophylaxis without CNI-associated side effects. So far, belatacept has been approved in combination with mycophenolate and steroids with better graft function, however, a slightly higher acute rejection rate. Recently, the combination of an mTOR inhibitor and belatacept with lymphocyte-depleting antibody induction and without maintenance steroids has been explored in two pilot studies with very low acute rejection rates, very good graft function, and an acceptable side effect profile. PMID:25959589

  16. mTOR signaling pathway genes in focal epilepsies.

    PubMed

    Baulac, S

    2016-01-01

    Focal epilepsies, where seizures initiate in spatially limited networks, are the most frequent epilepsy type, accounting for two-thirds of patients. Focal epilepsies have long been thought to be acquired disorders; several focal epilepsy syndromes are now proven to be (genetically heterogeneous) monogenic disorders. While earlier genetic studies have demonstrated a strong contribution of ion channel and neurotransmitter receptor genes, or synaptic secreted protein genes, later work has revealed a new class of genes encoding components of the mechanistic target of rapamycin (mTOR) signal transduction pathway. The mTOR pathway controls a myriad of biological processes among which cell growth and protein synthesis in response to several extracellular and intracellular. Recently, germline mutations have been found in genes encoding the components of the GATOR1 complex (DEPDC5, NPRL2, NPRL3), a repressor of mTORC1. These mutations are increasingly recognized as causing a wide and yet evolving spectrum of focal epilepsy syndromes, with and without cortical structural abnormalities (usually focal cortical dysplasia). Brain somatic mutations in the gene encoding mTOR (MTOR) have recently been linked to focal cortical dysplasia and other associated brain pathologies including hemimegalencephaly. This chapter reviews the genetics and neurobiology of DEPDC5, NPRL2, and NPRL3, and summarizes the clinical and molecular spectrum of GATOR1-related epilepsies. PMID:27323939

  17. Three 4-Letter Words of Hypertension-Related Cardiac Hypertrophy: TRPC, mTOR, and HDAC

    PubMed Central

    Kurdi, Mazen; Booz, George W.

    2011-01-01

    Left ventricular hypertrophy due to hypertension represents a major risk factor for adverse cardiovascular events and death. In recent years, the prevalence of cardiac hypertrophy has increased due to obesity and an aging population. Notably, a significant number of individuals have persistent cardiac hypertrophy in the face of blood pressure that is normalized by drug treatment. Thus, a better understanding of the processes underlying the cardiac remodeling events that are set into play by hypertension is needed. At the level of the cardiac myocytes, hypertrophic growth is often described as physiological, as occurs with exercise, or pathological, as seen with hypertension. Here we discuss recent developments in three areas that are fundamental to pathological hypertrophic growth of cardiac myocytes. These areas are the transient receptor potential canonical (TRPC) channels, mammalian target of rapamycin (mTOR) complexes, and histone deacetylase (HDAC) enzymes. In the last several years, studies in each of these areas have yielded new and exciting discoveries into the genesis of pathological growth of cardiac myocytes. The phosphoinositide 3-kinase – Akt signaling network may be the common denominator that links these areas together. Defining the interrelationship among TRPC channels, mTOR signaling, and HDAC enzymes is a promising, but challenging area of research. Such knowledge will undoubtedly lead to new drugs that better prevent or reverse left ventricular hypertension. PMID:21320507

  18. The role of mTOR inhibitors in the management of posttransplant malignancy.

    PubMed

    Monaco, Anthony P

    2009-01-27

    Organ transplant recipients given mammalian target of rapamycin inhibitor (mTORi) have reduced incidence of de novo posttransplant malignancies (dNPTMs). Posttransplant Kaposi's sarcoma and nonmelanotic skin malignancies (NMSC) frequently undergo remission/regression after conversion to mTORi immunosuppression (IS), especially early, small, and low-grade lesions, whereas larger, aggressive, and metastatic skin tumors are less likely to respond. mTORi-based IS is effective and well tolerated in orthotopic liver transplant patients with hepatocellular carcinoma (HCC) achieving excellent survival and disease-free intervals, particularly with extended criteria tumors, although the evidence that mTORi prevents HCC recurrence after orthotopic liver transplantation is only suggestive. Regression of metastatic HCC and other tumors and various forms of posttransplant lymphoproliferative disease have occurred after mTOR conversion. Documentation of regression/remission of other solid-organ dNPTM (colon, stomach, breast, etc.) after mTORi conversion is essentially absent with only anecdotal reports lacking follow-up data. Unfortunately, there is not a single reported prospective clinical trial powered for looking at the effect of mTORi IS in transplant recipients. Nevertheless, reduced incidence of all of dNPTMs and remission/regression of the commonest posttransplant tumors with mTOR therapy are strong reasons to expand the use of mTORi.

  19. Adaptation to chronic mTOR inhibition in cancer and in aging.

    PubMed

    Gilley, Rebecca; Balmanno, Kathryn; Cope, Claire L; Cook, Simon J

    2013-08-01

    The mTOR [mammalian (or mechanistic) target of rapamycin] protein kinase co-ordinates catabolic and anabolic processes in response to growth factors and nutrients and is a validated anticancer drug target. Rapamycin and related allosteric inhibitors of mTORC1 (mTOR complex 1) have had some success in specific tumour types, but have not exhibited broad anticancer activity, prompting the development of new ATP-competitive mTOR kinase inhibitors that inhibit both mTORC1 and mTORC2. In common with other targeted kinase inhibitors, tumours are likely to adapt and acquire resistance to mTOR inhibitors. In the present article, we review studies that describe how tumour cells adapt to become resistant to mTOR inhibitors. mTOR is a central signalling hub which responds to an array of signalling inputs and activates a range of downstream effector pathways. Understanding how this signalling network is remodelled and which pathways are invoked to sustain survival and proliferation in the presence of mTOR inhibitors can provide new insights into the importance of the various mTOR effector pathways and may suggest targets for intervention to combine with mTOR inhibitors. Finally, since chronic mTOR inhibition by rapamycin can increase lifespan and healthspan in nematodes, fruitflies and mice, we contrast these studies with tumour cell responses to mTOR inhibition. PMID:23863163

  20. Common corruption of the mTOR signaling network in human tumors.

    PubMed

    Menon, S; Manning, B D

    2008-12-01

    The mammalian target of rapamycin (mTOR) is responsive to numerous extracellular and intracellular cues and, through the formation of two physically and functionally distinct complexes, has a central role in the homeostatic control of cell growth, proliferation and survival. Through the aberrant activation of mTOR signaling, the perception of cellular growth signals becomes disconnected from the processes promoting cell growth, and this underlies the pathophysiology of a number of genetic tumor syndromes and cancers. Here, we review the oncogenes and tumor suppressors comprising the regulatory network upstream of mTOR, highlight the human cancers in which mTOR is activated and discuss how dysregulated mTOR signaling provides tumors a selective growth advantage. In addition, we discuss why activation of mTOR, as a consequence of distinct oncogenic events, results in diverse clinical outcomes, and how the complexity of the mTOR signaling network might dictate therapeutic approaches.

  1. South American Heart Transplantation Registry of patients receiving everolimus in their immunosuppressive regimens.

    PubMed

    Bortman, G V; Ceruti, B; Ahualli, L; Colque, R; Amuchástegui, M; Sgrosso, J L; Muñoz, J; Vulcano, N; Burgos, C; Diez, F; Rodriguez, M C; Perrone, S V

    2010-01-01

    The increasing number of heart transplant recipients receiving immunosuppression with mammalian target of rapamycin inhibitors prompted the implementation of a South American Transplant Physicians Group to register these patients in a database. Everolimus (EVL) is a signal proliferation inhibition that reduces graft vascular disease when used de novo. Recently, its administration has expanded to subjects with resistant rejection or with side effects due to other immunosuppressive drugs (calcineurin inhibitors and/or steroids), allowing for better regulation of the immunosuppressive regimen. Herein we have shown the data collected from patients receiving EVL in ten South American Heart Transplant Centers. We have concluded that the administration of EVL is a useful adjunctive therapy that allows the reduction or suspension of other immunosuppressive drugs that caused unwanted side effects, without a loss of immunosuppressive efficacy, with manageable side effects, and constituting a valuable therapeutic option. PMID:20172342

  2. Everolimus-eluting stent platforms in percutaneous coronary intervention: comparative effectiveness and outcomes

    PubMed Central

    Panoulas, Vasileios F; Mastoris, Ioannis; Konstantinou, Klio; Tespili, Maurizio; Ielasi, Alfonso

    2015-01-01

    Despite the remarkable benefits obtained following the introduction of the first-generation drug-eluting stent (DES), concerns were raised over its long-term safety, particularly with regard to very late (beyond 1 year) stent thrombosis. Newer-generation DESs have been developed to overcome this limitation using novel stent platforms, new drugs, more biocompatible durable polymers, and bioabsorbable polymers or backbones. To date, new-generation DESs have virtually replaced the use of first-generation DESs worldwide. In this review article, we discuss in detail the design, pharmacology, and mechanism of action of the newer-generation permanent and bioresorbable everolimus-eluting platforms. Furthermore, we present and evaluate the current evidence on the performance and safety of these devices compared to those of other available stent platforms. PMID:26244031

  3. mTOR is necessary for proper satellite cell activity and skeletal muscle regeneration

    SciTech Connect

    Zhang, Pengpeng; Liang, Xinrong; Shan, Tizhong; Jiang, Qinyang; Deng, Changyan; Zheng, Rong; Kuang, Shihuan

    2015-07-17

    The serine/threonine kinase mammalian target of rapamycin (mTOR) is a key regulator of protein synthesis, cell proliferation and energy metabolism. As constitutive deletion of Mtor gene results in embryonic lethality, the function of mTOR in muscle stem cells (satellite cells) and skeletal muscle regeneration remains to be determined. In this study, we established a satellite cell specific Mtor conditional knockout (cKO) mouse model by crossing Pax7{sup CreER} and Mtor{sup flox/flox} mice. Skeletal muscle regeneration after injury was severely compromised in the absence of Mtor, indicated by increased number of necrotic myofibers infiltrated by Evans blue dye, and reduced number and size of regenerated myofibers in the Mtor cKO mice compared to wild type (WT) littermates. To dissect the cellular mechanism, we analyzed satellite cell-derived primary myoblasts grown on single myofibers or adhered to culture plates. The Mtor cKO myoblasts exhibited defective proliferation and differentiation kinetics when compared to myoblasts derived from WT littermates. At the mRNA and protein levels, the Mtor cKO myoblasts expressed lower levels of key myogenic determinant genes Pax7, Myf5, Myod, Myog than did the WT myoblasts. These results suggest that mTOR is essential for satellite cell function and skeletal muscle regeneration through controlling the expression of myogenic genes. - Highlights: • Pax7{sup CreER} was used to delete Mtor gene in satellite cells. • Satellite cell specific deletion of Mtor impairs muscle regeneration. • mTOR is necessary for satellite cell proliferation and differentiation. • Deletion of Mtor leads to reduced expression of key myogenic genes.

  4. The inhibition of MAPK potentiates the anti-angiogenic efficacy of mTOR inhibitors

    SciTech Connect

    Dormond-Meuwly, Anne; Roulin, Didier; Dufour, Marc; Benoit, Michael; Demartines, Nicolas; Dormond, Olivier

    2011-04-22

    Highlights: {yields} Targeting mTOR in endothelial cell activates MAPK. {yields} Blocking MAPK enhances the anti-angiogenic effects of mTOR inhibitors. {yields} The anti-angiogenic efficacy of ATP-competitive inhibitors of mTOR is superior to that of rapamycin. -- Abstract: The mammalian target of rapamycin (mTOR) which is part of two functionally distinct complexes, mTORC1 and mTORC2, plays an important role in vascular endothelial cells. Indeed, the inhibition of mTOR with an allosteric inhibitor such as rapamycin reduces the growth of endothelial cell in vitro and inhibits angiogenesis in vivo. Recent studies have shown that blocking mTOR results in the activation of other prosurvival signals such as Akt or MAPK which counteract the growth inhibitory properties of mTOR inhibitors. However, little is known about the interactions between mTOR and MAPK in endothelial cells and their relevance to angiogenesis. Here we found that blocking mTOR with ATP-competitive inhibitors of mTOR or with rapamycin induced the activation of the mitogen-activated protein kinase (MAPK) in endothelial cells. Downregulation of mTORC1 but not mTORC2 had similar effects showing that the inhibition of mTORC1 is responsible for the activation of MAPK. Treatment of endothelial cells with mTOR inhibitors in combination with MAPK inhibitors reduced endothelial cell survival, proliferation, migration and tube formation more significantly than either inhibition alone. Similarly, in a tumor xenograft model, the anti-angiogenic efficacy of mTOR inhibitors was enhanced by the pharmacological blockade of MAPK. Taken together these results show that blocking mTORC1 in endothelial cells activates MAPK and that a combined inhibition of MAPK and mTOR has additive anti-angiogenic effects. They also provide a rationale to target both mTOR and MAPK simultaneously in anti-angiogenic treatment.

  5. Dexamethasone and BCAA Failed to Modulate Muscle Mass and mTOR Signaling in GH-Deficient Rats

    PubMed Central

    Nishida, Hikaru; Ikegami, Ayaka; Kaneko, Chiaki; Kakuma, Hitomi; Nishi, Hisano; Tanaka, Noriko; Aoyama, Michiko; Usami, Makoto; Okimura, Yasuhiko

    2015-01-01

    Branched-chain amino acids (BCAAs) and IGF-I, the secretion of which is stimulated by growth hormone (GH), prevent muscle atrophy. mTOR plays a pivotal role in the protective actions of BCAA and IGF-1. The pathway by which BCAA activates mTOR is different from that of IGF-1, which suggests that BCAA and GH work independently. We tried to examine whether BCAA exerts a protective effect against dexamethasone (Dex)-induced muscle atrophy independently of GH using GH-deficient spontaneous dwarf rats (SDRs). Unexpectedly, Dex did not induce muscle atrophy assessed by the measurement of cross-sectional area (CSA) of the muscle fibers and did not increase atrogin-1, MuRF1 and REDD1 expressions, which are activated during protein degradation. Glucocorticoid (GR) mRNA levels were higher in SDRs compared to GH-treated SDRs, indicating that the low expression of GR is not the reason of the defect of Dex’s action in SDRs. BCAA did not stimulate the phosphorylation of p70S6K or 4E-BP1, which stimulate protein synthesis. BCAA did not decrease the mRNA level of atrogin-1 or MuRF1. These findings suggested that Dex failed to modulate muscle mass and that BCAA was unable to activate mTOR in SDRs because these phosphorylations of p70S6K and 4E-BP1 and the reductions of these mRNAs are regulated by mTOR. In contrast, after GH supplementation, these responses to Dex were normalized and muscle fiber CSA was decreased by Dex. BCAA prevented the Dex-induced decrease in CSA. BCAA increased the phosphorylation of p70S6K and decreased the Dex-induced elevations of atrogin-1 and Bnip3 mRNAs. However, the amount of mTORC1 components including mTOR was not decreased in the SDRs compared to the normal rats. These findings suggest that GH increases mTORC1 activity but not its content to recover the action of BCAA in SDRs and that GH is required for actions of Dex and BCAA in muscles. PMID:26086773

  6. Everolimus-induced epithelial to mesenchymal transition in immortalized human renal proximal tubular epithelial cells: key role of heparanase

    PubMed Central

    2013-01-01

    Background Everolimus (EVE) is a drug widely used in several renal transplant protocols. Although characterized by a relatively low nephrotoxicity, it may induce several adverse effects including severe fibro-interstitial pneumonitis. The exact molecular/biological mechanism associated to these pro-fibrotic effects is unknown, but epithelial to mesenchymal transition (EMT) may have a central role. Additionally, heparanase, an enzyme recently associated with the progression of chronic allograft nephropathy, could contribute to activate this machinery in renal cells. Methods Several biomolecular strategies (RT-PCR, immunofluorescence, zymography and migration assay) have been used to assess the capability of EVE (10, 100, 200 and 500 nM) to induce an in vitro heparanase-mediated EMT in wild-type (WT) and Heparanase (HPSE)-silenced immortalized human renal epithelial proximal tubular cells (HK-2). Additionally, microarray technology was used to find additional biological elements involved in EVE-induced EMT. Results Biomolecular experiments demonstrated a significant up-regulation (more than 1.5 fold increase) of several genes encoding for well known EMT markers [(alpha-smooth muscle actin (α-SMA), Vimentin (VIM), Fibronectin (FN) and matrix metalloproteinase-9 (MMP9)], enhancement of MMP9 protein level and increment of cells motility in WT HK2 cells treated with high concentrations of EVE (higher than 100 nM). Similarly, immunofluorescence analysis showed that 100 nM of EVE increased α-SMA, VIM and FN protein expression in WT HK2 cells. All these effects were absent in both HPSE- and AKT-silenced cell lines. AKT is a protein having a central role in EMT. Additionally, microarray analysis identified other 2 genes significantly up-regulated in 100 nM EVE-treated cells (p < 0.005 and FDR < 5%): transforming growth factor beta-2 (TGFβ2) and epidermal growth factor receptor (EGFR). Real-time PCR analysis validated microarray. Conclusions Our in vitro study

  7. A Phase 1 Study of Everolimus + Weekly Cisplatin + Intensity Modulated Radiation Therapy in Head-and-Neck Cancer

    SciTech Connect

    Fury, Matthew G.; Lee, Nancy Y.; Sherman, Eric; Ho, Alan L.; Rao, Shyam; Heguy, Adriana; Shen, Ronglai; Korte, Susan; Lisa, Donna; Ganly, Ian; Patel, Snehal; Wong, Richard J.; Shaha, Ashok; Shah, Jatin; Haque, Sofia; Katabi, Nora; Pfister, David G.

    2013-11-01

    Purpose: Elevated expression of eukaryotic protein synthesis initiation factor 4E (eIF4E) in histologically cancer-free margins of resected head and neck squamous cell carcinomas (HNSCCs) is mediated by mammalian target of rapamycin complex 1 (mTORC1) and has been associated with increased risk of disease recurrence. Preclinically, inhibition of mTORC1 with everolimus sensitizes cancer cells to cisplatin and radiation. Methods and Materials: This was single-institution phase 1 study to establish the maximum tolerated dose of daily everolimus given with fixed dose cisplatin (30 mg/m{sup 2} weekly × 6) and concurrent intensity modulated radiation therapy for patients with locally and/or regionally advanced head-and-neck cancer. The study had a standard 3 + 3 dose-escalation design. Results: Tumor primary sites were oral cavity (4), salivary gland (4), oropharynx (2), nasopharynx (1), scalp (1), and neck node with occult primary (1). In 4 of 4 cases in which resected HNSCC surgical pathology specimens were available for immunohistochemistry, elevated expression of eIF4E was observed in the cancer-free margins. The most common grade ≥3 treatment-related adverse event was lymphopenia (92%), and dose-limiting toxicities (DLTs) were mucositis (n=2) and failure to thrive (n=1). With a median follow up of 19.4 months, 2 patients have experienced recurrent disease. The maximum tolerated dose was everolimus 5 mg/day. Conclusions: Head-and-neck cancer patients tolerated everolimus at therapeutic doses (5 mg/day) given with weekly cisplatin and intensity modulated radiation therapy. The regimen merits further evaluation, especially among patients who are status post resection of HNSCCs that harbor mTORC1-mediated activation of eIF4E in histologically negative surgical margins.

  8. Dual-Blocking of PI3K and mTOR Improves Chemotherapeutic Effects on SW620 Human Colorectal Cancer Stem Cells by Inducing Differentiation

    PubMed Central

    Kim, Buyun

    2016-01-01

    Cancer stem cells (CSCs) have tumor initiation, self-renewal, metastasis and chemo-resistance properties in various tumors including colorectal cancer. Targeting of CSCs may be essential to prevent relapse of tumors after chemotherapy. Phosphatidylinositol-3-kinase (PI3K) and mammalian target of rapamycin (mTOR) signals are central regulators of cell growth, proliferation, differentiation, and apoptosis. These pathways are related to colorectal tumorigenesis. This study focused on PI3K and mTOR pathways by inhibition which initiate differentiation of SW620 derived CSCs and investigated its effect on tumor progression. By using rapamycin, LY294002, and NVP-BEZ235, respectively, PI3K and mTOR signals were blocked independently or dually in colorectal CSCs. Colorectal CSCs gained their differentiation property and lost their stemness properties most significantly in dual-blocked CSCs. After treated with anti-cancer drug (paclitaxel) on the differentiated CSCs cell viability, self-renewal ability and differentiation status were analyzed. As a result dual-blocking group has most enhanced sensitivity for anti-cancer drug. Xenograft tumorigenesis assay by using immunodeficiency mice also shows that dual-inhibited group more effectively increased drug sensitivity and suppressed tumor growth compared to single-inhibited groups. Therefore it could have potent anti-cancer effects that dual-blocking of PI3K and mTOR induces differentiation and improves chemotherapeutic effects on SW620 human colorectal CSCs. PMID:26955235

  9. mTOR is necessary for proper satellite cell activity and skeletal muscle regeneration.

    PubMed

    Zhang, Pengpeng; Liang, Xinrong; Shan, Tizhong; Jiang, Qinyang; Deng, Changyan; Zheng, Rong; Kuang, Shihuan

    The serine/threonine kinase mammalian target of rapamycin (mTOR) is a key regulator of protein synthesis, cell proliferation and energy metabolism. As constitutive deletion of Mtor gene results in embryonic lethality, the function of mTOR in muscle stem cells (satellite cells) and skeletal muscle regeneration remains to be determined. In this study, we established a satellite cell specific Mtor conditional knockout (cKO) mouse model by crossing Pax7(CreER) and Mtor(flox/flox) mice. Skeletal muscle regeneration after injury was severely compromised in the absence of Mtor, indicated by increased number of necrotic myofibers infiltrated by Evans blue dye, and reduced number and size of regenerated myofibers in the Mtor cKO mice compared to wild type (WT) littermates. To dissect the cellular mechanism, we analyzed satellite cell-derived primary myoblasts grown on single myofibers or adhered to culture plates. The Mtor cKO myoblasts exhibited defective proliferation and differentiation kinetics when compared to myoblasts derived from WT littermates. At the mRNA and protein levels, the Mtor cKO myoblasts expressed lower levels of key myogenic determinant genes Pax7, Myf5, Myod, Myog than did the WT myoblasts. These results suggest that mTOR is essential for satellite cell function and skeletal muscle regeneration through controlling the expression of myogenic genes.

  10. mTOR Enhances Foam Cell Formation by Suppressing the Autophagy Pathway

    PubMed Central

    Li, Lingxia; Niu, Xiaolin; Dang, Xiaoyan; Li, Ping; Qu, Li; Bi, Xiaoju; Gao, Yanxia; Hu, Yanfen; Li, Manxiang; Qiao, Wanhai; Peng, Zhuo; Pan, Longfei

    2014-01-01

    Recently, autophagy has drawn more attention in cardiovascular disease as it has important roles in lipid metabolism. Mammalian target of rapamycin (mTOR) is a key regulator of autophagy; however, its effect on atherosclerosis and the underlying mechanism remains undefined. In this study, an obvious upregulation of mTOR and p-mTOR protein was observed in macrophage-derived foam cells. Blocking mTOR expression with specific small interference RNA (siRNA) dramatically suppressed foam cell formation, accompanied by a decrease of lipid deposition. Further mechanistic analysis indicated that suppressing mTOR expression significantly upregulated autophagic marker LC3 expression and downregulated autophagy substrate p62 levels, indicating that mTOR silencing triggered autophagosome formation. Moreover, blocking mTOR expression obviously accelerated neutral lipid delivery to lysosome and cholesterol efflux from foam cells, implying that mTOR could induce macrophage foam cell formation by suppressing autophagic pathway. Further, mTOR silencing significantly upregulated ULK1 expression, which was accounted for mTOR-induced foam cell formation via autophagic pathway as treatment with ULK1 siRNA dampened LC3-II levels and increased p62 expression, concomitant with lipid accumulation and decreased cholesterol efflux from foam cells. Together, our data provide an insight into how mTOR accelerates the pathological process of atherosclerosis. Accordingly, blocking mTOR levels may be a promising therapeutic agent against atherosclerotic complications. PMID:24512183

  11. mTOR signaling and its roles in normal and abnormal brain development

    PubMed Central

    Takei, Nobuyuki; Nawa, Hiroyuki

    2014-01-01

    Target of rapamycin (TOR) was first identified in yeast as a target molecule of rapamycin, an anti-fugal and immunosuppressant macrolide compound. In mammals, its orthologue is called mammalian TOR (mTOR). mTOR is a serine/threonine kinase that converges different extracellular stimuli, such as nutrients and growth factors, and diverges into several biochemical reactions, including translation, autophagy, transcription, and lipid synthesis among others. These biochemical reactions govern cell growth and cause cells to attain an anabolic state. Thus, the disruption of mTOR signaling is implicated in a wide array of diseases such as cancer, diabetes, and obesity. In the central nervous system, the mTOR signaling cascade is activated by nutrients, neurotrophic factors, and neurotransmitters that enhances protein (and possibly lipid) synthesis and suppresses autophagy. These processes contribute to normal neuronal growth by promoting their differentiation, neurite elongation and branching, and synaptic formation during development. Therefore, disruption of mTOR signaling may cause neuronal degeneration and abnormal neural development. While reduced mTOR signaling is associated with neurodegeneration, excess activation of mTOR signaling causes abnormal development of neurons and glia, leading to brain malformation. In this review, we first introduce the current state of molecular knowledge of mTOR complexes and signaling in general. We then describe mTOR activation in neurons, which leads to translational enhancement, and finally discuss the link between mTOR and normal/abnormal neuronal growth during development. PMID:24795562

  12. mTOR signaling in osteosarcoma: Oncogenesis and therapeutic aspects (Review).

    PubMed

    Hu, Kai; Dai, Hai-Bo; Qiu, Zhi-Long

    2016-09-01

    The mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase that belongs to the phosphoinositide-3-kinase (PI3K)-related kinase family. Oncogenic activation of mTOR signaling significantly contributes to the progression of different types of cancers including osteosarcoma (OS; the most common primary malignant tumor of bone). In the present study, we review the association of the mTOR signaling pathway with OS, and the possible effective treatment strategies by targeting this pathway. In the metastatic behavior of OS, one of the most common actionable aberrations was found in the PI3K/Akt/mTOR pathway. Upon phosphorylation, activated mTOR contributes to OS cellular transformation and poor cancer prognosis via downstream effectors such as S6K1, 4EBP1 and eIF4E, which are overexpressed in OS. Targeting the mTOR complex is a significant approach in cancer therapeutic research, and of course, rapamycin is the primary inhibitor of mTOR. Various other chemotherapeutic molecules have also shown potential activity against mTOR. As mTOR is a new promising oncological target and blockade of the mTOR pathway with selective inhibitors has significant potential in OS therapeutic research, the development of the optimal dose, regimen and a rationale for the use of mTOR inhibitors in combination with other anticancer agents may provide a successful treatment strategy for OS. PMID:27430283

  13. Development of ATP-competitive mTOR inhibitors.

    PubMed

    Liu, Qingsong; Kang, Seong A; Thoreen, Carson C; Hur, Wooyoung; Wang, Jinhua; Chang, Jae Won; Markhard, Andrew; Zhang, Jianming; Sim, Taebo; Sabatini, David M; Gray, Nathanael S

    2012-01-01

    The mammalian Target of Rapamycin (mTOR)-mediated signaling transduction pathway has been observed to be deregulated in a wide variety of cancer and metabolic diseases. Despite extensive clinical development efforts, the well-known allosteric mTOR inhibitor rapamycin and structurally related rapalogs have failed to show significant single-agent antitumor efficacy in most types of cancer. This limited clinical success may be due to the inability of the rapalogs to maintain a complete blockade mTOR-mediated signaling. Therefore, numerous efforts have been initiated to develop ATP-competitive mTOR inhibitors that would block both mTORC1 and mTORC2 complex activity. Here, we describe our experimental approaches to develop Torin1 using a medium throughput cell-based screening assay and structure-guided drug design.

  14. Frontier of Epilepsy Research - mTOR signaling pathway

    PubMed Central

    2011-01-01

    Studies of epilepsy have mainly focused on the membrane proteins that control neuronal excitability. Recently, attention has been shifting to intracellular proteins and their interactions, signaling cascades and feedback regulation as they relate to epilepsy. The mTOR (mammalian target of rapamycin) signal transduction pathway, especially, has been suggested to play an important role in this regard. These pathways are involved in major physiological processes as well as in numerous pathological conditions. Here, involvement of the mTOR pathway in epilepsy will be reviewed by presenting; an overview of the pathway, a brief description of key signaling molecules, a summary of independent reports and possible implications of abnormalities of those molecules in epilepsy, a discussion of the lack of experimental data, and questions raised for the understanding its epileptogenic mechanism. PMID:21467839

  15. Cost-effectiveness analysis of everolimus plus exemestane versus exemestane alone for treatment of hormone receptor positive metastatic breast cancer.

    PubMed

    Diaby, Vakaramoko; Adunlin, Georges; Zeichner, Simon B; Avancha, Kiran; Lopes, Gilberto; Gluck, Stefan; Montero, Alberto J

    2014-09-01

    Everolimus in combination with exemestane significantly improved progression-free survival compared to exemestane alone in patients previously treated with non-steroidal aromatase inhibitors in the BOLERO-2 trial. As a result, this combination has been approved by the food and drug administration to treat postmenopausal women with hormone receptor positive and HER2 negative metastatic breast cancer. A cost-effectiveness analysis was conducted to determine whether everolimus represents good value for money, utilizing data from BOLERO-2. A decision-analytic model was used to estimate the incremental cost-effectiveness ratio between treatment arms of the BOLERO-2 trial. Costs were obtained from the Center for Medicare Services drug payment table and physician fee schedule. Benefits were expressed as quality-adjusted progression-free survival weeks (QAPFW) and quality-adjusted progression-free years (QAPFY), with utilities/disutilities derived from the literature. Deterministic and probabilistic sensitivity analyses were performed. A willingness to pay threshold of 1-3 times the per capita gross domestic product was adopted, as per the definition of the World Health Organization. The U.S. per capita gross domestic product in 2013 was $49,965; thus, a threshold varying between $49,965 and $149,895 was considered. Everolimus/exemestane had an incremental benefit of 11.88 QAPFW (0.22 QAPFY) compared to exemestane and an incremental cost of $60,574. This translated into an ICER of $265,498.5/QAPFY. Univariate sensitivity analyses showed important variations of the ICER, ranging between $189,836.4 and $530,947/QAPFY. A tornado analysis suggested that the key drivers of our model, by order of importance, included health utility value for stable disease, everolimus acquisition costs, and transition probabilities from the stable to the progression states. The Monte-Carlo simulation showed results that were similar to the base-case analysis. This cost-effectiveness analysis

  16. On the participation of mTOR in recognition memory.

    PubMed

    Myskiw, Jociane C; Rossato, Janine I; Bevilaqua, Lia R M; Medina, Jorge H; Izquierdo, Iván; Cammarota, Martín

    2008-03-01

    Evidence indicates that activation of the neuronal protein synthesis machinery is required in areas of the brain relevant to memory for consolidation and persistence of the mnemonic trace. Here, we report that inhibition of hippocampal mTOR, a protein kinase involved in the initiation of mRNA translation, immediately or 180min but not 540min after training impairs consolidation of long-term object recognition memory without affecting short-term memory retention or exploratory behavior. When infused into dorsal CA1 after long-term memory reactivation in the presence of familiar objects the mTOR inhibitor rapamycin (RAP) did not affect retention. However, when given immediately after exposing animals to a novel and a familiar object, RAP impaired memory for both of them. The amnesic effect of the post-retrieval administration of RAP was long-lasting, did not happen after exposure to two novel objects or following exploration of the training arena in the absence of other stimuli, suggesting that it was contingent with reactivation of the consolidated trace in the presence of a behaviorally relevant and novel cue. Our results indicate that mTOR activity is required in the dorsal hippocampus for consolidation of object recognition memory and suggest that inhibition of this kinase after memory retrieval in the presence of a particular set of cues hinders persistence of the original recognition memory trace.

  17. Mechanistic target of rapamycin (Mtor) is essential for murine embryonic heart development and growth.

    PubMed

    Zhu, Yi; Pires, Karla M P; Whitehead, Kevin J; Olsen, Curtis D; Wayment, Benjamin; Zhang, Yi Cheng; Bugger, Heiko; Ilkun, Olesya; Litwin, Sheldon E; Thomas, George; Kozma, Sara C; Abel, E Dale

    2013-01-01

    Mechanistic target of rapamycin (Mtor) is required for embryonic inner cell mass proliferation during early development. However, Mtor expression levels are very low in the mouse heart during embryogenesis. To determine if Mtor plays a role during mouse cardiac development, cardiomyocyte specific Mtor deletion was achieved using α myosin heavy chain (α-MHC) driven Cre recombinase. Initial mosaic expression of Cre between embryonic day (E) 10.5 and E11.5 eliminated a subset of cardiomyocytes with high Cre activity by apoptosis and reduced overall cardiac proliferative capacity. The remaining cardiomyocytes proliferated and expanded normally. However loss of 50% of cardiomyocytes defined a threshold that impairs the ability of the embryonic heart to sustain the embryo's circulatory requirements. As a result 92% of embryos with cardiomyocyte Mtor deficiency died by the end of gestation. Thus Mtor is required for survival and proliferation of cardiomyocytes in the developing heart.

  18. Crosstalk between Ca2+ signaling and mitochondrial H2O2 is required for rotenone inhibition of mTOR signaling pathway leading to neuronal apoptosis

    PubMed Central

    Zhou, Qian; Zhang, Ruijie; Zhang, Hai; Liu, Wen; Xu, Chong; Liu, Lei; Huang, Shile; Chen, Long

    2016-01-01

    Rotenone, a neurotoxic pesticide, induces loss of dopaminergic neurons related to Parkinson's disease. Previous studies have shown that rotenone induces neuronal apoptosis partly by triggering hydrogen peroxide (H2O2)-dependent suppression of mTOR pathway. However, the underlying mechanism is not fully understood. Here, we show that rotenone elevates intracellular free calcium ion ([Ca2+]i) level, and activates CaMKII, resulting in inhibition of mTOR signaling and induction of neuronal apoptosis. Chelating [Ca2+]i with BAPTA/AM, preventing extracellular Ca2+ influx using EGTA, inhibiting CaMKII with KN93, or silencing CaMKII significantly attenuated rotenone-induced H2O2 production, mTOR inhibition, and cell death. Interestingly, using TTFA, antimycin A, catalase or Mito-TEMPO, we found that rotenone-induced mitochondrial H2O2 also in turn elevated [Ca2+]i level, thereby stimulating CaMKII, leading to inhibition of mTOR pathway and induction of neuronal apoptosis. Expression of wild type mTOR or constitutively active S6K1, or silencing 4E-BP1 strengthened the inhibitory effects of catalase, Mito-TEMPO, BAPTA/AM or EGTA on rotenone-induced [Ca2+]i elevation, CaMKII phosphorylation and neuronal apoptosis. Together, the results indicate that the crosstalk between Ca2+ signaling and mitochondrial H2O2 is required for rotenone inhibition of mTOR-mediated S6K1 and 4E-BP1 pathways. Our findings suggest that how to control over-elevation of intracellular Ca2+ and overproduction of mitochondrial H2O2 may be a new approach to deal with the neurotoxicity of rotenone. PMID:26859572

  19. Adapting the Stress Response: Viral Subversion of the mTOR Signaling Pathway.

    PubMed

    Le Sage, Valerie; Cinti, Alessandro; Amorim, Raquel; Mouland, Andrew J

    2016-01-01

    The mammalian target of rapamycin (mTOR) is a central regulator of gene expression, translation and various metabolic processes. Multiple extracellular (growth factors) and intracellular (energy status) molecular signals as well as a variety of stressors are integrated into the mTOR pathway. Viral infection is a significant stress that can activate, reduce or even suppress the mTOR signaling pathway. Consequently, viruses have evolved a plethora of different mechanisms to attack and co-opt the mTOR pathway in order to make the host cell a hospitable environment for replication. A more comprehensive knowledge of different viral interactions may provide fruitful targets for new antiviral drugs.

  20. Resveratrol induces autophagy by directly inhibiting mTOR through ATP competition

    PubMed Central

    Park, Dohyun; Jeong, Heeyoon; Lee, Mi Nam; Koh, Ara; Kwon, Ohman; Yang, Yong Ryoul; Noh, Jungeun; Suh, Pann-Ghill; Park, Hwangseo; Ryu, Sung Ho

    2016-01-01

    Resveratrol (RSV) is a natural polyphenol that has a beneficial effect on health, and resveratrol-induced autophagy has been suggested to be a key process in mediating many beneficial effects of resveratrol, such as reduction of inflammation and induction of cancer cell death. Although various resveratrol targets have been suggested, the molecule that mediates resveratrol-induced autophagy remains unknown. Here, we demonstrate that resveratrol induces autophagy by directly inhibiting the mTOR-ULK1 pathway. We found that inhibition of mTOR activity and presence of ULK1 are required for autophagy induction by resveratrol. In line with this mTOR dependency, we found that resveratrol suppresses the viability of MCF7 cells but not of SW620 cells, which are mTOR inhibitor sensitive and insensitive cancer cells, respectively. We also found that resveratrol-induced cancer cell suppression occurred ULK1 dependently. For the mechanism of action of resveratrol on mTOR inhibition, we demonstrate that resveratrol directly inhibits mTOR. We found that resveratrol inhibits mTOR by docking onto the ATP-binding pocket of mTOR (i.e., it competes with ATP). We propose mTOR as a novel direct target of resveratrol, and inhibition of mTOR is necessary for autophagy induction. PMID:26902888

  1. Roles of mTOR complexes in the kidney: implications for renal disease and transplantation.

    PubMed

    Fantus, Daniel; Rogers, Natasha M; Grahammer, Florian; Huber, Tobias B; Thomson, Angus W

    2016-10-01

    The mTOR pathway has a central role in the regulation of cell metabolism, growth and proliferation. Studies involving selective gene targeting of mTOR complexes (mTORC1 and mTORC2) in renal cell populations and/or pharmacologic mTOR inhibition have revealed important roles of mTOR in podocyte homeostasis and tubular transport. Important advances have also been made in understanding the role of mTOR in renal injury, polycystic kidney disease and glomerular diseases, including diabetic nephropathy. Novel insights into the roles of mTORC1 and mTORC2 in the regulation of immune cell homeostasis and function are helping to improve understanding of the complex effects of mTOR targeting on immune responses, including those that impact both de novo renal disease and renal allograft outcomes. Extensive experience in clinical renal transplantation has resulted in successful conversion of patients from calcineurin inhibitors to mTOR inhibitors at various times post-transplantation, with excellent long-term graft function. Widespread use of this practice has, however, been limited owing to mTOR-inhibitor- related toxicities. Unique attributes of mTOR inhibitors include reduced rates of squamous cell carcinoma and cytomegalovirus infection compared to other regimens. As understanding of the mechanisms by which mTORC1 and mTORC2 drive the pathogenesis of renal disease progresses, clinical studies of mTOR pathway targeting will enable testing of evolving hypotheses. PMID:27477490

  2. Current development of the second generation of mTOR inhibitors as anticancer agents.

    PubMed

    Zhou, Hong-Yu; Huang, Shi-Le

    2012-01-01

    The mammalian target of rapamycin (mTOR), a serine/threonine protein kinase, acts as a "master switch" for cellular anabolic and catabolic processes, regulating the rate of cell growth and proliferation. Dysregulation of the mTOR signaling pathway occurs frequently in a variety of human tumors, and thus, mTOR has emerged as an important target for the design of anticancer agents. mTOR is found in two distinct multiprotein complexes within cells, mTORC1 and mTORC2. These two complexes consist of unique mTOR-interacting proteins and are regulated by different mechanisms. Enormous advances have been made in the development of drugs known as mTOR inhibitors. Rapamycin, the first defined inhibitor of mTOR, showed effectiveness as an anticancer agent in various preclinical models. Rapamycin analogues (rapalogs) with better pharmacologic properties have been developed. However, the clinical success of rapalogs has been limited to a few types of cancer. The discovery that mTORC2 directly phosphorylates Akt, an important survival kinase, adds new insight into the role of mTORC2 in cancer. This novel finding prompted efforts to develop the second generation of mTOR inhibitors that are able to target both mTORC1 and mTORC2. Here, we review the recent advances in the mTOR field and focus specifically on the current development of the second generation of mTOR inhibitors as anticancer agents. PMID:22059905

  3. The mTOR signalling cascade: paving new roads to cure neurological disease.

    PubMed

    Crino, Peter B

    2016-07-01

    Defining the multiple roles of the mechanistic (formerly 'mammalian') target of rapamycin (mTOR) signalling pathway in neurological diseases has been an exciting and rapidly evolving story of bench-to-bedside translational research that has spanned gene mutation discovery, functional experimental validation of mutations, pharmacological pathway manipulation, and clinical trials. Alterations in the dual contributions of mTOR - regulation of cell growth and proliferation, as well as autophagy and cell death - have been found in developmental brain malformations, epilepsy, autism and intellectual disability, hypoxic-ischaemic and traumatic brain injuries, brain tumours, and neurodegenerative disorders. mTOR integrates a variety of cues, such as growth factor levels, oxygen levels, and nutrient and energy availability, to regulate protein synthesis and cell growth. In line with the positioning of mTOR as a pivotal cell signalling node, altered mTOR activation has been associated with a group of phenotypically diverse neurological disorders. To understand how altered mTOR signalling leads to such divergent phenotypes, we need insight into the differential effects of enhanced or diminished mTOR activation, the developmental context of these changes, and the cell type affected by altered signalling. A particularly exciting feature of the tale of mTOR discovery is that pharmacological mTOR inhibitors have shown clinical benefits in some neurological disorders, such as tuberous sclerosis complex, and are being considered for clinical trials in epilepsy, autism, dementia, traumatic brain injury, and stroke. PMID:27340022

  4. Current development of the second generation of mTOR inhibitors as anticancer agents

    PubMed Central

    Zhou, Hong-Yu; Huang, Shi-Le

    2012-01-01

    The mammalian target of rapamycin (mTOR), a serine/threonine protein kinase, acts as a “master switch” for cellular anabolic and catabolic processes, regulating the rate of cell growth and proliferation. Dysregulation of the mTOR signaling pathway occurs frequently in a variety of human tumors, and thus, mTOR has emerged as an important target for the design of anticancer agents. mTOR is found in two distinct multiprotein complexes within cells, mTORC1 and mTORC2. These two complexes consist of unique mTOR-interacting proteins and are regulated by different mechanisms. Enormous advances have been made in the development of drugs known as mTOR inhibitors. Rapamycin, the first defined inhibitor of mTOR, showed effectiveness as an anticancer agent in various preclinical models. Rapamycin analogues (rapalogs) with better pharmacologic properties have been developed. However, the clinical success of rapalogs has been limited to a few types of cancer. The discovery that mTORC2 directly phosphorylates Akt, an important survival kinase, adds new insight into the role of mTORC2 in cancer. This novel finding prompted efforts to develop the second generation of mTOR inhibitors that are able to target both mTORC1 and mTORC2. Here, we review the recent advances in the mTOR field and focus specifically on the current development of the second generation of mTOR inhibitors as anticancer agents. PMID:22059905

  5. Mechanical stimulation induces mTOR signaling via an ERK-independent mechanism: implications for a direct activation of mTOR by phosphatidic acid.

    PubMed

    You, Jae Sung; Frey, John W; Hornberger, Troy A

    2012-01-01

    Signaling by mTOR is a well-recognized component of the pathway through which mechanical signals regulate protein synthesis and muscle mass. However, the mechanisms involved in the mechanical regulation of mTOR signaling have not been defined. Nevertheless, recent studies suggest that a mechanically-induced increase in phosphatidic acid (PA) may be involved. There is also evidence which suggests that mechanical stimuli, and PA, utilize ERK to induce mTOR signaling. Hence, we reasoned that a mechanically-induced increase in PA might promote mTOR signaling via an ERK-dependent mechanism. To test this, we subjected mouse skeletal muscles to mechanical stimulation in the presence or absence of a MEK/ERK inhibitor, and then measured several commonly used markers of mTOR signaling. Transgenic mice expressing a rapamycin-resistant mutant of mTOR were also used to confirm the validity of these markers. The results demonstrated that mechanically-induced increases in p70(s6k) T389 and 4E-BP1 S64 phosphorylation, and unexpectedly, a loss in total 4E-BP1, were fully mTOR-dependent signaling events. Furthermore, we determined that mechanical stimulation induced these mTOR-dependent events, and protein synthesis, through an ERK-independent mechanism. Similar to mechanical stimulation, exogenous PA also induced mTOR-dependent signaling via an ERK-independent mechanism. Moreover, PA was able to directly activate mTOR signaling in vitro. Combined, these results demonstrate that mechanical stimulation induces mTOR signaling, and protein synthesis, via an ERK-independent mechanism that potentially involves a direct interaction of PA with mTOR. Furthermore, it appears that a decrease in total 4E-BP1 may be part of the mTOR-dependent mechanism through which mechanical stimuli activate protein synthesis. PMID:23077579

  6. Mechanical stimulation induces mTOR signaling via an ERK-independent mechanism: implications for a direct activation of mTOR by phosphatidic acid.

    PubMed

    You, Jae Sung; Frey, John W; Hornberger, Troy A

    2012-01-01

    Signaling by mTOR is a well-recognized component of the pathway through which mechanical signals regulate protein synthesis and muscle mass. However, the mechanisms involved in the mechanical regulation of mTOR signaling have not been defined. Nevertheless, recent studies suggest that a mechanically-induced increase in phosphatidic acid (PA) may be involved. There is also evidence which suggests that mechanical stimuli, and PA, utilize ERK to induce mTOR signaling. Hence, we reasoned that a mechanically-induced increase in PA might promote mTOR signaling via an ERK-dependent mechanism. To test this, we subjected mouse skeletal muscles to mechanical stimulation in the presence or absence of a MEK/ERK inhibitor, and then measured several commonly used markers of mTOR signaling. Transgenic mice expressing a rapamycin-resistant mutant of mTOR were also used to confirm the validity of these markers. The results demonstrated that mechanically-induced increases in p70(s6k) T389 and 4E-BP1 S64 phosphorylation, and unexpectedly, a loss in total 4E-BP1, were fully mTOR-dependent signaling events. Furthermore, we determined that mechanical stimulation induced these mTOR-dependent events, and protein synthesis, through an ERK-independent mechanism. Similar to mechanical stimulation, exogenous PA also induced mTOR-dependent signaling via an ERK-independent mechanism. Moreover, PA was able to directly activate mTOR signaling in vitro. Combined, these results demonstrate that mechanical stimulation induces mTOR signaling, and protein synthesis, via an ERK-independent mechanism that potentially involves a direct interaction of PA with mTOR. Furthermore, it appears that a decrease in total 4E-BP1 may be part of the mTOR-dependent mechanism through which mechanical stimuli activate protein synthesis.

  7. Everolimus with low-dose tacrolimus in simultaneous pancreas and kidney transplantation.

    PubMed

    Sageshima, Junichiro; Ciancio, Gaetano; Chen, Linda; Dohi, Takehiko; El-Hinnawi, Ashraf; Paloyo, Siegfredo; Misawa, Ryosuke; Ekwenna, Obi; Yatawatta, Ashanga; Burke, George W

    2014-07-01

    The efficacy and safety of everolimus (EVR) in simultaneous pancreas and kidney transplantation (SPKT) is unclear. We retrospectively evaluated 25 consecutive SPKT recipients at our center from November 2011 to March 2013. All patients received dual induction (Thymoglobulin/basiliximab) and low-dose tacrolimus plus corticosteroids. Nine patients who received EVR were compared with 14 patients who received enteric-coated mycophenolate sodium (EC-MPS); two patients who received sirolimus were excluded from the analysis. With a median follow-up of 14 months, the pancreas graft survival rate was 100% in both groups, and the kidney graft survival rate was 100% and 93% in EVR and EC-MPS patients, respectively. One EC-MPS patient lost her kidney graft from proteinuric kidney disease. Another EC-MPS patient received treatment for clinically diagnosed pancreas and kidney graft rejection. No rejection was observed in EVR patients. Serum creatinine and HbA1c levels were similar between the groups. There was no significant difference of surgical or medical complications. In conclusion, EVR seems to provide comparable short-term outcome to EC-MPS when combined with low-dose tacrolimus/steroids and dual induction therapy. A larger study with a longer follow-up is required to further assess this combination.

  8. Usefulness of Everolimus-Eluting Coronary Stent Implantation in Patients on Maintenance Hemodialysis.

    PubMed

    Ikari, Yuji; Kyono, Hiroyuki; Isshiki, Takaaki; Ishizuka, Shuichi; Nasu, Kenya; Sano, Koichi; Okada, Hisayuki; Sugano, Teruyasu; Uehara, Yoshiki

    2015-09-15

    The outcomes of second-generation drug-eluting stent (DES) are unknown in patients on maintenance hemodialysis (HD) although HD has been reported as a strong predictor of adverse outcome after the first-generation DES implantation. The OUCH-PRO Study is a prospective multicenter single-arm registry design to study clinical and angiographic outcomes after everolimus-eluting stent (EES). Patients who underwent maintenance HD were prospectively enrolled at the time of elective coronary intervention using EES. Quantitative coronary angiography was performed in an independent core laboratory. The primary end point was the occurrence of target vessel failure (TVF) defined as cardiac death, myocardial infarction (MI), and target vessel revascularization at 1 year. A total of 123 patients were enrolled and 161 EES were implanted. The TVF rate at 1 year was 18% (4% cardiac death, 0% MI, 17% target vessel revascularization). No stent thrombosis was documented. Other clinical events at 1 year were 3% noncardiac death, 3% stroke, and 9% non-target-vessel revascularization. Late lumen loss in stent was 0.37 ± 0.63 mm at 8 months. In conclusion, EES had a high TVF rate and great late lumen loss in patients on HD compared with previous huge EES data in non-HD patients. PMID:26219496

  9. Efficacy and Safety of Low-Dose Everolimus as Maintenance Immunosuppression in Cardiac Transplant Recipients

    PubMed Central

    Fuchs, Uwe; Zittermann, Armin; Schulz, Uwe; Gummert, Jan F.

    2012-01-01

    For cardiac transplant (CTx) recipients, the recommended everolimus (EVL) dose is 0.75 mg bid or 1.5 mg bid and the target trough blood level is 3–8 μg/L. We studied a cohort of 56 CTx patients with chronic kidney disease receiving 0.75 mg bid EVL to maintain blood levels of 5–8 ug/L (designated RD group) and a cohort of 51 CTx patients with chronic kidney disease receiving 0.5 mg bid to maintain blood levels of 3–5 ug/L (designated LD group). The primary endpoint was a composite of death, rejection and premature EVL discontinuation up to 1 year after introduction of EVL. The primary endpoint was reached by 32% of patients in the LD group and by 41.1% of patients in the RD group (P = 0.361). Biochemical safety parameters were comparable in both groups. Our results indicate that low-dose EVL may be as effective and safe as regular dose EVL. PMID:22577516

  10. RTOG 0913: A Phase 1 Study of Daily Everolimus (RAD001) in Combination With Radiation Therapy and Temozolomide in Patients With Newly Diagnosed Glioblastoma

    SciTech Connect

    Chinnaiyan, Prakash; Won, Minhee; Wen, Patrick Y.; Wendland, Merideth; Dipetrillo, Thomas A.; Corn, Benjamin W.; Mehta, Minesh P.

    2013-08-01

    Purpose: To determine the safety of the mammalian target of rapamycin inhibitor everolimus (RAD001) administered daily with concurrent radiation and temozolomide in newly diagnosed glioblastoma patients. Methods and Materials: Everolimus was administered daily with concurrent radiation (60 Gy in 30 fractions) and temozolomide (75 mg/m{sup 2} per day). Everolimus was escalated from 2.5 mg/d (dose level 1) to 5 mg/d (dose level 2) to 10 mg/d (dose level 3). Adjuvant temozolomide was delivered at 150 to 200 mg/m{sup 2} on days 1 to 5, every 28 days, for up to 12 cycles, with concurrent everolimus at the previously established daily dose of 10 mg/d. Dose escalation continued if a dose level produced dose-limiting toxicities (DLTs) in fewer than 3 of the first 6 evaluable patients. Results: Between October 28, 2010, and July 2, 2012, the Radiation Therapy Oncology Group 0913 protocol initially registered a total of 35 patients, with 25 patients successfully meeting enrollment criteria receiving the drug and evaluable for toxicity. Everolimus was successfully escalated to the predetermined maximum tolerated dose of 10 mg/d. Two of the first 6 eligible patients had a DLT at each dose level. DLTs included gait disturbance, febrile neutropenia, rash, fatigue, thrombocytopenia, hypoxia, ear pain, headache, and mucositis. Other common toxicities were grade 1 or 2 hypercholesterolemia and hypertriglyceridemia. At the time of analysis, there was 1 death reported, which was attributed to tumor progression. Conclusions: Daily oral everolimus (10 mg) combined with both concurrent radiation and temozolomide followed by adjuvant temozolomide is well tolerated, with an acceptable toxicity profile. A randomized phase 2 clinical trial with mandatory correlative biomarker analysis is currently under way, designed to both determine the efficacy of this regimen and identify molecular determinants of response.

  11. The mTOR pathway in obesity driven gastrointestinal cancers: Potential targets and clinical trials.

    PubMed

    Malley, Cian O; Pidgeon, Graham P

    2016-06-01

    The mechanistic target of rapamycin (mTOR) is a crucial point of convergence between growth factor signalling, metabolism, nutrient status and cellular proliferation. The mTOR pathway is heavily implicated in the progression of many cancers and is emerging as an important driver of gastrointestinal (GI) malignancies. Due to its central role in adapting metabolism to environmental conditions, mTOR signalling is also believed to be critical in the development of obesity. Recent research has delineated that excessive nutrient intake can promote signalling through the mTOR pathway and possibly evoke changes to cellular metabolism that could accelerate obesity related cancers. Acting through its two effector complexes mTORC1 and mTORC2, mTOR dictates the transcription of genes important in glycolysis, lipogenesis, protein translation and synthesis and has recently been defined as a central mediator of the Warburg effect in cancer cells. Activation of the mTOR pathway is involved in both the pathogenesis of GI malignancies and development of resistance to conventional chemotherapy and radiotherapy. The use of mTOR inhibitors is a promising therapeutic option in many GI malignancies, with greatest clinical efficacy seen in combination regimens. Recent research has also provided insight into crosstalk between mTOR and other pathways which could potentially expand the list of therapeutic targets in the mTOR pathway. Here we review the available strategies for targeting the mTOR pathway in GI cancers. We discuss current clinical trials of both established and novel mTOR inhibitors, with particular focus on combinations of these drugs with conventional chemotherapy, radiotherapy and targeted therapies.

  12. Skeletal myocyte hypertrophy requires mTOR kinase activity and S6K1

    SciTech Connect

    Park, In-Hyun . E-mail: ihpark@uiuc.edu; Erbay, Ebru; Nuzzi, Paul; Chen Jie

    2005-09-10

    The protein kinase mammalian target of rapamycin (mTOR) is a central regulator of cell proliferation and growth, with the ribosomal subunit S6 kinase 1 (S6K1) as one of the key downstream signaling effectors. A critical role of mTOR signaling in skeletal muscle differentiation has been identified recently, and an unusual regulatory mechanism independent of mTOR kinase activity and S6K1 is revealed. An mTOR pathway has also been reported to regulate skeletal muscle hypertrophy, but the regulatory mechanism is not completely understood. Here, we report the investigation of mTOR's function in insulin growth factor I (IGF-I)-induced C2C12 myotube hypertrophy. Added at a later stage when rapamycin no longer had any effect on normal myocyte differentiation, rapamycin completely blocked myocyte hypertrophy as measured by myotube diameter. Importantly, a concerted increase of average myonuclei per myotube was observed in IGF-I-stimulated myotubes, which was also inhibited by rapamycin added at a time when it no longer affected normal differentiation. The mTOR protein level, its catalytic activity, its phosphorylation on Ser2448, and the activity of S6K1 were all found increased in IGF-I-stimulated myotubes compared to unstimulated myotubes. Using C2C12 cells stably expressing rapamycin-resistant forms of mTOR and S6K1, we provide genetic evidence for the requirement of mTOR and its downstream effector S6K1 in the regulation of myotube hypertrophy. Our results suggest distinct mTOR signaling mechanisms in different stages of skeletal muscle development: While mTOR regulates the initial myoblast differentiation in a kinase-independent and S6K1-independent manner, the hypertrophic function of mTOR requires its kinase activity and employs S6K1 as a downstream effector.

  13. Ampelopsin suppresses breast carcinogenesis by inhibiting the mTOR signalling pathway.

    PubMed

    Chang, Hui; Peng, Xiaoli; Bai, Qian; Zhou, Yong; Yu, Xiaoping; Zhang, Qianyong; Zhu, Jundong; Mi, Mantian

    2014-08-01

    The mammalian target of rapamycin (mTOR), which is a master regulator of cellular catabolism and anabolism, plays an important role in tumourigenesis and progression. In this study, we report the chemopreventive effect of the dietary compound ampelopsin (AMP) on breast carcinogenesis in vivo and in vitro, which acts by inhibiting the mTOR signalling pathway. Our study indicates that AMP treatment effectively suppresses 1-methyl-1-nitrosourea (MNU)-induced breast carcinogenesis in rats and inhibits 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P)-induced cellular carcinogenesis. Additionally, AMP inhibits the growth of breast cancer cells in vitro and in vivo. The activity of mTOR kinase was found to be significantly increased in a time-dependent manner during chronic breast carcinogenesis, and this increase can be suppressed by AMP co-treatment. AMP also effectively suppresses mTOR activity in breast cancer MDA-MB-231 cells. We also demonstrated that AMP is an effective mTOR inhibitor that binds to one site on the mTOR target in two ways. Further studies confirmed that AMP inhibits the activation of Akt, suppresses the formation of mTOR complexes (mTORC)1/2 by dissociating regulatory-associated protein of mTOR and rapamycin-insensitive companion of mTOR and, consequently, decreases the activation of the downstream targets of mTOR, including ribosomal p70-S6 kinase, ribosomal protein S6, eukaryotic translation initiation factor 4B and eukaryotic translation initiation factor 4E-binding protein 1. These finding suggest that AMP is a bioactive natural chemopreventive agent against breast carcinogenesis and is an effective mTOR inhibitor that may be developed as a useful chemotherapeutic agent in the treatment of breast cancer. PMID:24861637

  14. A phase II trial of bevacizumab and everolimus as treatment for patients with refractory, progressive intracranial meningioma.

    PubMed

    Shih, Kent C; Chowdhary, Sajeel; Rosenblatt, Paul; Weir, Alva B; Shepard, Gregg C; Williams, Jeffrey T; Shastry, Mythili; Burris, Howard A; Hainsworth, John D

    2016-09-01

    Meningiomas that progress after standard therapies are challenging with limited effective chemotherapy options. This phase II trial evaluated the efficacy of everolimus plus bevacizumab in patients with recurrent, progressive meningioma after treatment with surgical resection and local radiotherapy when appropriate. Patients with recurrent meningioma (WHO grade I, II, or III) following standard treatments with surgical resection and radiotherapy received bevacizumab (10 mg/kg IV days 1 and 15) and everolimus (10 mg PO daily) each 28 day cycle. Evaluation of response occurred every 2 cycles. The primary endpoint was progression-free survival (PFS). Secondary endpoints included response rate, overall survival and safety. Seventeen patients with a median age of 59 years (29-84) received study treatment. WHO grades at study entry included: I, 5 (29 %); II, 7 (41 %); III, 4 (24 %); unknown, 1 (6 %). Patients received a median of 8 cycles (1-37); all patients are off study treatment. A best response of SD was observed in 15 patients (88 %), and 6 patients had SD for >12 months. Overall median PFS was 22 months (95 % CI 4.5-26.8) and was greater for patients with WHO grade II and III compared to grade I tumors (22.0 months vs 17.5 months). Four patients discontinued treatment due to toxicity (proteinuria, 2; colitis, 1, thrombocytopenia, 1). However, other grade 3 toxicity was uncommon, and no patient had grade 4 toxicity. The combination of everolimus and bevacizumab was well-tolerated, and produced stable disease in 88 % of patients; the median duration of disease stabilization of 10 months (2-29). The median PFS from this prospective trial was similar to previous retrospective reports of bevacizumab in the treatment of recurrent meningioma.

  15. Promotion of ovarian follicle growth following mTOR activation: synergistic effects of AKT stimulators.

    PubMed

    Cheng, Yuan; Kim, Jaehong; Li, Xiao Xiao; Hsueh, Aaron J

    2015-01-01

    Mammalian target of rapamycin (mTOR) is a serine/threonine kinase and mTOR signaling is important in regulating cell growth and proliferation. Recent studies using oocyte- and granulosa cell-specific deletion of mTOR inhibitor genes TSC1 or TSC2 demonstrated the important role of mTOR signaling in the promotion of ovarian follicle development. We now report that treatment of ovaries from juvenile mice with an mTOR activator MHY1485 stimulated mTOR, S6K1 and rpS6 phosphorylation. Culturing ovaries for 4 days with MHY1485 increased ovarian explant weights and follicle development. In vivo studies further demonstrated that pre-incubation of these ovaries with MHY1485 for 2 days, followed by allo-grafting into kidney capsules of adult ovariectomized hosts for 5 days, led to marked increases in graft weights and promotion of follicle development. Mature oocytes derived from MHY1485-activated ovarian grafts could be successfully fertilized, leading the delivery of healthy pups. We further treated ovaries with the mTOR activator together with AKT activators (PTEN inhibitor and phosphoinositol-3-kinase stimulator) before grafting and found additive enhancement of follicle growth. Our studies demonstrate the ability of an mTOR activator in promoting follicle growth, leading to a potential strategy to stimulate preantral follicle growth in infertile patients.

  16. Correlative Analysis of Genetic Alterations and Everolimus Benefit in Hormone Receptor–Positive, Human Epidermal Growth Factor Receptor 2–Negative Advanced Breast Cancer: Results From BOLERO-2

    PubMed Central

    Chen, David; Piccart, Martine; Rugo, Hope S.; Burris, Howard A.; Pritchard, Kathleen I.; Campone, Mario; Noguchi, Shinzaburo; Perez, Alejandra T.; Deleu, Ines; Shtivelband, Mikhail; Masuda, Norikazu; Dakhil, Shaker; Anderson, Ian; Robinson, Douglas M.; He, Wei; Garg, Abhishek; McDonald, E. Robert; Bitter, Hans; Huang, Alan; Taran, Tetiana; Bachelot, Thomas; Lebrun, Fabienne; Lebwohl, David; Baselga, José

    2016-01-01

    Purpose To explore the genetic landscape of tumors from patients enrolled on the BOLERO-2 trial to identify potential correlations between genetic alterations and efficacy of everolimus treatment. The BOLERO-2 trial has previously demonstrated that the addition of everolimus to exemestane prolonged progression-free survival by more than twofold in patients with hormone receptor–positive, human epidermal growth factor receptor 2–negative, advanced breast cancer previously treated with nonsteroidal aromatase inhibitors. Patients and Methods Next-generation sequencing was used to analyze genetic status of cancer-related genes in 302 archival tumor specimens from patients representative of the BOLERO-2 study population. Correlations between the most common somatic alterations and degree of chromosomal instability, and treatment effect of everolimus were investigated. Results Progression-free survival benefit with everolimus was maintained regardless of alteration status of PIK3CA, FGFR1, and CCND1 or the pathways of which they are components. However, quantitative differences in everolimus benefit were observed between patient subgroups defined by the exon-specific mutations in PIK3CA (exon 20 v 9) or by different degrees of chromosomal instability in the tumor tissues. Conclusion The data from this exploratory analysis suggest that the efficacy of everolimus was largely independent of the most commonly altered genes or pathways in hormone receptor–positive, human epidermal growth factor receptor 2–negative breast cancer. The potential impact of chromosomal instabilities and low-frequency genetic alterations on everolimus efficacy warrants further investigation. PMID:26503204

  17. mTOR signaling controls VGLUT2 expression to maintain pain hypersensitivity after tissue injury.

    PubMed

    Izumi, Y; Sasaki, M; Hashimoto, S; Sawa, T; Amaya, F

    2015-11-12

    Mammalian target of rapamycin (mTOR) is a serine-threonine protein kinase that controls protein synthesis in the nervous system. Here, we characterized the role of protein synthesis regulation due to mTOR signaling in rat dorsal root ganglion (DRG) following plantar incision. The number of phosphorylated mTOR (p-mTOR)-positive neurons was increased 2-4days after the incision. Rapamycin inhibited p-mTOR expression in the DRG and thermal hypersensitivity 3days but not 1day after the incision. Vesicular glutamate transporter 2 (VGLUT2) expression was increased after the plantar incision, which was inhibited by rapamycin. These results demonstrated that tissue injury induces phosphorylation of mTOR and increased protein level of VGLUT2 in the DRG neurons. mTOR phosphorylation involves in maintenance of injury-induced thermal hypersensitivity.

  18. Targeting bone metastatic cancer: Role of the mTOR pathway.

    PubMed

    Bertoldo, Francesco; Silvestris, Franco; Ibrahim, Toni; Cognetti, Francesco; Generali, Daniele; Ripamonti, Carla Ida; Amadori, Dino; Colleoni, Marco Angelo; Conte, Pierfranco; Del Mastro, Lucia; De Placido, Sabino; Ortega, Cinzia; Santini, Daniele

    2014-04-01

    One of the great challenges of cancer medicine is to develop effective treatments for bone metastatic cancer. Most patients with advanced solid tumors will develop bone metastasis and will suffer from skeletal related events associated with this disease. Although some therapies are available to manage symptoms derived from bone metastases, an effective treatment has not been developed yet. The mammalian target of rapamycin (mTOR) pathway regulates cell growth and survival. Alterations in mTOR signaling have been associated with pathological malignancies, including bone metastatic cancer. Inhibition of mTOR signaling might therefore be a promising alternative for bone metastatic cancer management. This review summarizes the current knowledge on mTOR pathway signaling in bone tissue and provides an overview on the known effects of mTOR inhibition in bone cancer, both in in vitro and in vivo models.

  19. Systemic effects of treatment with mTOR inhibitors in tuberous sclerosis complex: a comprehensive review.

    PubMed

    Sadowski, K; Kotulska, K; Schwartz, R A; Jóźwiak, S

    2016-04-01

    Tuberous sclerosis complex (TSC) is a genetic multisystem disorder associated with constitutive overactivation of the mammalian target of rapamycin (mTOR) pathway and characterized by development of benign tumours in various organs. mTOR inhibitors have proven to be effective in the targeted therapy of certain TSC-associated pathologies such as subependymal giant cell astrocytomas (SEGAs) and renal angiomyolipomas (AMLs). Accumulating experimental and clinical data suggest that mTOR inhibitors might have a systemic, disease-modifying influence on affected individuals. This systematic review provides an analysis of available clinical data concerning systemic effect of mTOR inhibitors and the influence of mTOR inhibition on different manifestations of TSC in individual patients.

  20. The Role of Mechanistic Target of Rapamycin (mTOR) Complexes Signaling in the Immune Responses

    PubMed Central

    Soliman, Ghada A.

    2013-01-01

    The mechanistic Target of Rapamycin (mTOR) is an evolutionarily conserved serine/threonine kinase which is a member of the PI3K related kinase (PIKK) family. mTOR emerged as a central node in cellular metabolism, cell growth, and differentiation, as well as cancer metabolism. mTOR senses the nutrients, energy, insulin, growth factors, and environmental cues and transmits signals to downstream targets to effectuate the cellular and metabolic response. Recently, mTOR was also implicated in the regulation of both the innate and adaptive immune responses. This paper will summarize the current knowledge of mTOR, as related to the immune microenvironment and immune responses. PMID:23783557

  1. Discovery of triazine-benzimidazoles as selective inhibitors of mTOR.

    PubMed

    Peterson, Emily A; Andrews, Paul S; Be, Xuhai; Boezio, Alessandro A; Bush, Tammy L; Cheng, Alan C; Coats, James R; Colletti, Adria E; Copeland, Katrina W; DuPont, Michelle; Graceffa, Russell; Grubinska, Barbara; Harmange, Jean-Christophe; Kim, Joseph L; Mullady, Erin L; Olivieri, Philip; Schenkel, Laurie B; Stanton, Mary K; Teffera, Yohannes; Whittington, Douglas A; Cai, Ti; La, Daniel S

    2011-04-01

    mTOR is part of the PI3K/AKT pathway and is a central regulator of cell growth and survival. Since many cancers display mutations linked to the mTOR signaling pathway, mTOR has emerged as an important target for oncology therapy. Herein, we report the discovery of triazine benzimidazole inhibitors that inhibit mTOR kinase activity with up to 200-fold selectivity over the structurally homologous kinase PI3Kα. When tested in a panel of cancer cell lines displaying various mutations, a selective inhibitor from this series inhibited cellular proliferation with a mean IC(50) of 0.41 μM. Lead compound 42 demonstrated up to 83% inhibition of mTOR substrate phosphorylation in a murine pharmacodynamic model.

  2. Incidence and time course of everolimus-related adverse events in postmenopausal women with hormone receptor-positive advanced breast cancer: insights from BOLERO-2

    PubMed Central

    Rugo, H. S.; Pritchard, K. I.; Gnant, M.; Noguchi, S.; Piccart, M.; Hortobagyi, G.; Baselga, J.; Perez, A.; Geberth, M.; Csoszi, T.; Chouinard, E.; Srimuninnimit, V.; Puttawibul, P.; Eakle, J.; Feng, W.; Bauly, H.; El-Hashimy, M.; Taran, T.; Burris, H. A.

    2014-01-01

    Background In the BOLERO-2 trial, everolimus (EVE), an inhibitor of mammalian target of rapamycin, demonstrated significant clinical benefit with an acceptable safety profile when administered with exemestane (EXE) in postmenopausal women with hormone receptor-positive (HR+) advanced breast cancer. We report on the incidence, time course, severity, and resolution of treatment-emergent adverse events (AEs) as well as incidence of dose modifications during the extended follow-up of this study. Patients and methods Patients were randomized (2:1) to receive EVE 10 mg/day or placebo (PBO), with open-label EXE 25 mg/day (n = 724). The primary end point was progression-free survival. Secondary end points included overall survival, objective response rate, and safety. Safety evaluations included recording of AEs, laboratory values, dose interruptions/adjustments, and study drug discontinuations. Results The safety population comprised 720 patients (EVE + EXE, 482; PBO + EXE, 238). The median follow-up was 18 months. Class-effect toxicities, including stomatitis, pneumonitis, and hyperglycemia, were generally of mild or moderate severity and occurred relatively early after treatment initiation (except pneumonitis); incidence tapered off thereafter. EVE dose reduction and interruption (360 and 705 events, respectively) required for AE management were independent of patient age. The median duration of dose interruption was 7 days. Discontinuation of both study drugs because of AEs was higher with EVE + EXE (9%) versus PBO + EXE (3%). Conclusions Most EVE-associated AEs occur soon after initiation of therapy, are typically of mild or moderate severity, and are generally manageable with dose reduction and interruption. Discontinuation due to toxicity was uncommon. Understanding the time course of class-effect AEs will help inform preventive and monitoring strategies as well as patient education. Trial registration number NCT00863655. PMID:24615500

  3. Ammonia Induces Autophagy through Dopamine Receptor D3 and MTOR.

    PubMed

    Li, Zhiyuan; Ji, Xinmiao; Wang, Wenchao; Liu, Juanjuan; Liang, Xiaofei; Wu, Hong; Liu, Jing; Eggert, Ulrike S; Liu, Qingsong; Zhang, Xin

    2016-01-01

    Hyperammonemia is frequently seen in tumor microenvironments as well as in liver diseases where it can lead to severe brain damage or death. Ammonia induces autophagy, a mechanism that tumor cells may use to protect themselves from external stresses. However, how cells sense ammonia has been unclear. Here we show that culture medium alone containing Glutamine can generate milimolar of ammonia at 37 degrees in the absence of cells. In addition, we reveal that ammonia acts through the G protein-coupled receptor DRD3 (Dopamine receptor D3) to induce autophagy. At the same time, ammonia induces DRD3 degradation, which involves PIK3C3/VPS34-dependent pathways. Ammonia inhibits MTOR (mechanistic target of Rapamycin) activity and localization in cells, which is mediated by DRD3. Therefore, ammonia has dual roles in autophagy: one to induce autophagy through DRD3 and MTOR, the other to increase autophagosomal pH to inhibit autophagic flux. Our study not only adds a new sensing and output pathway for DRD3 that bridges ammonia sensing and autophagy induction, but also provides potential mechanisms for the clinical consequences of hyperammonemia in brain damage, neurodegenerative diseases and tumors.

  4. mTOR Regulates Cellular Iron Homeostasis through Tristetraprolin

    PubMed Central

    Bayeva, Marina; Khechaduri, Arineh; Puig, Sergi; Chang, Hsiang-Chun; Patial, Sonika; Blackshear, Perry J.; Ardehali, Hossein

    2013-01-01

    SUMMARY Iron is an essential cofactor with unique redox properties. Iron regulatory proteins 1 and 2 (IRP1/2) have been established as important regulators of cellular iron homeostasis, but little is known about the role of other pathways in this process. Here we report that the mammalian target of rapamycin (mTOR) regulates iron homeostasis by modulating transferrin receptor 1 (TfR1) stability and altering cellular iron flux. Mechanistic studies identify tristetraprolin (TTP), a protein involved in anti-inflammatory response, as the downstream target of mTOR that binds to and enhances degradation of TfR1 mRNA. We also show that TTP is strongly induced by iron chelation, promotes downregulation of iron-requiring genes in both mammalian and yeast cells, and modulates survival in low-iron states. Taken together, our data uncover a link between metabolic, inflammatory, and iron regulatory pathways, and point towards the existence of a yeast-like TTP-mediated iron conservation program in mammals. PMID:23102618

  5. Meta-analysis of long-term clinical outcomes of everolimus-eluting stents.

    PubMed

    Toyota, Toshiaki; Shiomi, Hiroki; Morimoto, Takeshi; Kimura, Takeshi

    2015-07-15

    The superiority of everolimus-eluting stents (EES) over sirolimus-eluting stents (SES) for long-term clinical outcomes has not been yet firmly established. We conducted a systematic review and a meta-analysis of randomized controlled trials (RCTs) comparing EES directly with SES using the longest available follow-up data. We searched PubMed, the Cochrane database, and ClinicalTrials.gov for RCTs comparing outcomes between EES and SES and identified 13,434 randomly assigned patients from 14 RCTs. EES was associated with significantly lower risks than SES for definite stent thrombosis (ST), definite/probable ST, target-lesion revascularization (TLR), and major adverse cardiac events (MACE). The risks for all-cause death and myocardial infarction were similar between EES and SES. By the stratified analysis according to the timing after stent implantation, the favorable trend of EES relative to SES for ST, TLR, and MACE was consistently observed both within and beyond 1 year. The lower risk of EES relative to SES for MACE beyond 1 year was statistically significant (pooled odds ratio 0.77, 95% confidence interval 0.61 to 0.96, p = 0.02). In conclusion, the current meta-analysis of 14 RCTs directly comparing EES with SES suggested that EES provided improvement in both safety and efficacy; EES compared with SES was associated with significantly lower risk for definite ST, definite/probable ST, TLR, and MACE. The direction and magnitude of the effect beyond 1 year were comparable with those observed within 1 year.

  6. Mammalian Target of Rapamycin (mTOR) Tagging Promotes Dendritic Branch Variability through the Capture of Ca2+/Calmodulin-dependent Protein Kinase II α (CaMKIIα) mRNAs by the RNA-binding Protein HuD*

    PubMed Central

    Sosanya, Natasha M.; Cacheaux, Luisa P.; Workman, Emily R.; Niere, Farr; Perrone-Bizzozero, Nora I.; Raab-Graham, Kimberly F.

    2015-01-01

    The fate of a memory, whether stored or forgotten, is determined by the ability of an active or tagged synapse to undergo changes in synaptic efficacy requiring protein synthesis of plasticity-related proteins. A synapse can be tagged, but without the “capture” of plasticity-related proteins, it will not undergo long lasting forms of plasticity (synaptic tagging and capture hypothesis). What the “tag” is and how plasticity-related proteins are captured at tagged synapses are unknown. Ca2+/calmodulin-dependent protein kinase II α (CaMKIIα) is critical in learning and memory and is synthesized locally in neuronal dendrites. The mechanistic (mammalian) target of rapamycin (mTOR) is a protein kinase that increases CaMKIIα protein expression; however, the mechanism and site of dendritic expression are unknown. Herein, we show that mTOR activity mediates the branch-specific expression of CaMKIIα, favoring one secondary, daughter branch over the other in a single neuron. mTOR inhibition decreased the dendritic levels of CaMKIIα protein and mRNA by shortening its poly(A) tail. Overexpression of the RNA-stabilizing protein HuD increased CaMKIIα protein levels and preserved its selective expression in one daughter branch over the other when mTOR was inhibited. Unexpectedly, deleting the third RNA recognition motif of HuD, the domain that binds the poly(A) tail, eliminated the branch-specific expression of CaMKIIα when mTOR was active. These results provide a model for one molecular mechanism that may underlie the synaptic tagging and capture hypothesis where mTOR is the tag, preventing deadenylation of CaMKIIα mRNA, whereas HuD captures and promotes its expression in a branch-specific manner. PMID:25944900

  7. Response to everolimus is seen in TSC-associated SEGAs and angiomyolipomas independent of mutation type and site in TSC1 and TSC2.

    PubMed

    Kwiatkowski, David J; Palmer, Michael R; Jozwiak, Sergiusz; Bissler, John; Franz, David; Segal, Scott; Chen, David; Sampson, Julian R

    2015-12-01

    Tuberous sclerosis complex is an autosomal dominant disorder that occurs owing to inactivating mutations in either TSC1 or TSC2. Tuberous sclerosis complex-related tumors in the brain, such as subependymal giant cell astrocytoma, and in the kidney, such as angiomyolipoma, can cause significant morbidity and mortality. Recently, randomized clinical trials (EXIST-1 and EXIST-2) of everolimus for each of these tuberous sclerosis complex-associated tumors demonstrated the benefit of this drug, which blocks activated mammalian target of rapamycin complex 1. Here we report on the spectrum of mutations seen in patients treated during these trials and the association between mutation and response. TSC2 mutations were predominant among patients in both trials and were present in nearly all subjects with angiomyolipoma in whom a mutation was identified (97%), whereas TSC1 mutations were rare in those subjects (3%). The spectrum of mutations seen in each gene was similar to those previously reported. In both trials, there was no apparent association between mutation type or location within each gene and response to everolimus. Everolimus responses were also seen at a similar frequency for the 16-18% of patients in each trial in whom no mutation in either gene was identified. These observations confirm the strong association between TSC2 mutation and angiomyolipoma burden seen in previous studies, and they indicate that everolimus response occurs regardless of mutation type or location or when no mutation in TSC1 or TSC2 has been identified.

  8. Response to everolimus is seen in TSC-associated SEGAs and angiomyolipomas independent of mutation type and site in TSC1 and TSC2

    PubMed Central

    Kwiatkowski, David J; Palmer, Michael R; Jozwiak, Sergiusz; Bissler, John; Franz, David; Segal, Scott; Chen, David; Sampson, Julian R

    2015-01-01

    Tuberous sclerosis complex is an autosomal dominant disorder that occurs owing to inactivating mutations in either TSC1 or TSC2. Tuberous sclerosis complex-related tumors in the brain, such as subependymal giant cell astrocytoma, and in the kidney, such as angiomyolipoma, can cause significant morbidity and mortality. Recently, randomized clinical trials (EXIST-1 and EXIST-2) of everolimus for each of these tuberous sclerosis complex-associated tumors demonstrated the benefit of this drug, which blocks activated mammalian target of rapamycin complex 1. Here we report on the spectrum of mutations seen in patients treated during these trials and the association between mutation and response. TSC2 mutations were predominant among patients in both trials and were present in nearly all subjects with angiomyolipoma in whom a mutation was identified (97%), whereas TSC1 mutations were rare in those subjects (3%). The spectrum of mutations seen in each gene was similar to those previously reported. In both trials, there was no apparent association between mutation type or location within each gene and response to everolimus. Everolimus responses were also seen at a similar frequency for the 16–18% of patients in each trial in whom no mutation in either gene was identified. These observations confirm the strong association between TSC2 mutation and angiomyolipoma burden seen in previous studies, and they indicate that everolimus response occurs regardless of mutation type or location or when no mutation in TSC1 or TSC2 has been identified. PMID:25782670

  9. A Phase II Study of BEZ235 in Patients with Everolimus-resistant, Advanced Pancreatic Neuroendocrine Tumours

    PubMed Central

    FAZIO, NICOLA; BUZZONI, ROBERTO; BAUDIN, ERIC; ANTONUZZO, LORENZO; HUBNER, RICHARD A.; LAHNER, HARALD; DE HERDER, WOUTER W.; RADERER, MARKUS; TEULÉ, ALEXANDRE; CAPDEVILA, JAUME; LIBUTTI, STEVEN K.; KULKE, MATTHEW H.; SHAH, MANISHA; DEY, DEBARSHI; TURRI, SABINE; AIMONE, PAOLA; MASSACESI, CRISTIAN; VERSLYPE, CHRIS

    2016-01-01

    Background This was a two-stage, phase II trial of the dual phosphatidylinositol 3-kinase/mammalian target of rapamycin inhibitor BEZ235 in patients with everolimus-resistant pancreatic neuroendocrine tumours (pNETs) (NCT01658436). Patients and Methods In stage 1, 11 patients received 400 mg BEZ235 orally twice daily (bid). Due to tolerability concerns, a further 20 patients received BEZ235 300 mg bid. Stage 2 would be triggered by a 16-week progression-free survival (PFS) rate of ≥60% in stage 1. Results As of 30 June, 2014, 29/31 patients had discontinued treatment. Treatment-related grade 3/4 adverse events were reported in eight (72.7%) patients at 400 mg and eight (40.0%) patients at 300 mg, including hyperglycaemia, diarrhoea, nausea, and vomiting. The estimated 16-week PFS rate was 51.6% (90% confidence interval=35.7–67.3%). Conclusion BEZ235 was poorly tolerated by patients with everolimus-resistant pNETs at 400 and 300 mg bid doses. Although evidence of disease stability was observed, the study did not proceed to stage 2. PMID:26851029

  10. ATP-competitive inhibitors of mTOR: new perspectives in the treatment of renal cell carcinoma.

    PubMed

    Roulin, Didier; Demartines, Nicolas; Dormond, Olivier

    2011-04-01

    Targeting mTOR (mammalian target of rapamycin) is an effective approach in the treatment of advanced RCC (renal cell carcinoma). Rapamycin-like drugs (rapalogues) have shown clinical activities and have been approved for the treatment of RCC. Recently, with the development of ATP-competitive inhibitors of mTOR, therapies targeting mTOR have entered a new era. Here, we discuss the biological relevance of blocking mTOR in RCC and review the mechanisms of action of rapalogues in RCC. We also advance some perspectives on the use of ATP-competitive inhibitors of mTOR in RCC.

  11. mTOR signaling in skeletal muscle during sepsis and inflammation: Where does it all go wrong?

    PubMed Central

    Frost, Robert A.; Lang, Charles H.

    2013-01-01

    The mammalian target of rapamycin (mTOR) is an evolutionarily conserved protein kinase that exquisitely regulates protein metabolism in skeletal muscle. mTOR integrates input from amino acids, growth factors and intracellular cues to make or break muscle protein. mTOR accomplishes this task by stimulating the phosphorylation of substrates that control protein translation while simultaneously inhibiting proteasomal and autophagic protein degradation. In a metabolic twist of fate, sepsis induces muscle atrophy in part by the aberrant regulation of mTOR. In this review we track the steps of normal mTOR signaling in muscle and examine where they go astray in sepsis and inflammation. PMID:21487027

  12. Muscle inactivation of mTOR causes metabolic and dystrophin defects leading to severe myopathy.

    PubMed

    Risson, Valérie; Mazelin, Laetitia; Roceri, Mila; Sanchez, Hervé; Moncollin, Vincent; Corneloup, Claudine; Richard-Bulteau, Hélène; Vignaud, Alban; Baas, Dominique; Defour, Aurélia; Freyssenet, Damien; Tanti, Jean-François; Le-Marchand-Brustel, Yannick; Ferrier, Bernard; Conjard-Duplany, Agnès; Romanino, Klaas; Bauché, Stéphanie; Hantaï, Daniel; Mueller, Matthias; Kozma, Sara C; Thomas, George; Rüegg, Markus A; Ferry, Arnaud; Pende, Mario; Bigard, Xavier; Koulmann, Nathalie; Schaeffer, Laurent; Gangloff, Yann-Gaël

    2009-12-14

    Mammalian target of rapamycin (mTOR) is a key regulator of cell growth that associates with raptor and rictor to form the mTOR complex 1 (mTORC1) and mTORC2, respectively. Raptor is required for oxidative muscle integrity, whereas rictor is dispensable. In this study, we show that muscle-specific inactivation of mTOR leads to severe myopathy, resulting in premature death. mTOR-deficient muscles display metabolic changes similar to those observed in muscles lacking raptor, including impaired oxidative metabolism, altered mitochondrial regulation, and glycogen accumulation associated with protein kinase B/Akt hyperactivation. In addition, mTOR-deficient muscles exhibit increased basal glucose uptake, whereas whole body glucose homeostasis is essentially maintained. Importantly, loss of mTOR exacerbates the myopathic features in both slow oxidative and fast glycolytic muscles. Moreover, mTOR but not raptor and rictor deficiency leads to reduced muscle dystrophin content. We provide evidence that mTOR controls dystrophin transcription in a cell-autonomous, rapamycin-resistant, and kinase-independent manner. Collectively, our results demonstrate that mTOR acts mainly via mTORC1, whereas regulation of dystrophin is raptor and rictor independent. PMID:20008564

  13. Inhibition of mTOR promotes hyperthermia sensitivity in SMMC-7721 human hepatocellular carcinoma cell line

    PubMed Central

    WANG, QING-LIANG; LIU, BO; LI, XIAO-JIE; HU, KUN-PENG; ZHAO, KUN; YE, XIAO-MING

    2016-01-01

    The mammalian target of rapamycin (mTOR) is a critical mediator of the phosphoinositide 3-kinase/protein kinase B/mTOR signaling pathway, and mTOR activity is induced following heat shock. Thermotherapy is used to treat hepatocellular carcinoma (HCC). However, the role of mTOR in modulating thermosensitivity in HCC has yet to be elucidated. In the present study, the antisense plasmid pEGFP-C1-mTOR was transfected into SMMC-7721 cells, and the expression levels of mTOR were analyzed by reverse transcription-polymerase chain reaction and western blot analysis. The thermal responses of the transfected cells were also examined. The results revealed that SMMC-7721 cells were sensitive to heat treatment, and cell viability was significantly inhibited following hyperthermia treatment (P<0.01). The mRNA and protein expression levels of mTOR decreased post-transfection. Cell proliferation, colony-forming ability and motility were all significantly decreased following hyperthermia treatment in the transfected cells. Flow cytometry analysis demonstrated that apoptosis was significantly increased following treatment (P<0.01). The number of cells in S phase was increased, and the cell cycle was arrested in S phase. In conclusion, inhibition of mTOR increased the thermosensitivity of SMMC-7721 cells by increasing cellular apoptosis and inducing S phase arrest. PMID:26998020

  14. mTOR signaling in neural stem cells: from basic biology to disease.

    PubMed

    Magri, Laura; Galli, Rossella

    2013-08-01

    The mammalian target of rapamycin (mTOR) pathway is a central controller of growth and homeostasis, and, as such, is implicated in disease states where growth is deregulated, namely cancer, metabolic diseases, and hamartoma syndromes like tuberous sclerosis complex (TSC). Accordingly, mTOR is also a pivotal regulator of the homeostasis of several distinct stem cell pools in which it finely tunes the balance between stem cell self-renewal and differentiation. mTOR hyperactivation in neural stem cells (NSCs) has been etiologically linked to the development of TSC-associated neurological lesions, such as brain hamartomas and benign tumors. Animal models generated by deletion of mTOR upstream regulators in different types of NSCs reproduce faithfully some of the TSC neurological alterations. Thus, mTOR dysregulation in NSCs seems to be responsible for the derangement of their homeostasis, thus leading to TSC development. Here we review recent advances in the molecular dissection of the mTOR cascade, its involvement in the maintenance of stem cell compartments, and in particular the implications of mTOR hyperactivation in NSCs in vivo and in vitro.

  15. Activation of mTOR: a culprit of Alzheimer’s disease?

    PubMed Central

    Cai, Zhiyou; Chen, Guanghui; He, Wenbo; Xiao, Ming; Yan, Liang-Jun

    2015-01-01

    Alzheimer’s disease (AD) is characterized by cognitive impairment in clinical presentation, and by β-amyloid (Aβ) production and the hyper-phosphorylation of tau in basic research. More highlights demonstrate that the activation of the mammalian target of rapamycin (mTOR) enhances Aβ generation and deposition by modulating amyloid precursor protein (APP) metabolism and upregulating β- and γ-secretases. mTOR, an inhibitor of autophagy, decreases Aβ clearance by scissoring autophagy function. mTOR regulates Aβ generation or Aβ clearance by regulating several key signaling pathways, including phosphoinositide 3-kinase (PI3-K)/protein kinase B (Akt), glycogen synthase kinase 3 [GSK-3], AMP-activated protein kinase (AMPK), and insulin/insulin-like growth factor 1 (IGF-1). The activation of mTOR is also a contributor to aberrant hyperphosphorylated tau. Rapamycin, the inhibitor of mTOR, may mitigate cognitive impairment and inhibit the pathologies associated with amyloid plaques and neurofibrillary tangles by promoting autophagy. Furthermore, the upstream and downstream components of mTOR signaling are involved in the pathogenesis and progression of AD. Hence, inhibiting the activation of mTOR may be an important therapeutic target for AD. PMID:25914534

  16. microRNA-496 - A new, potentially aging-relevant regulator of mTOR.

    PubMed

    Rubie, Claudia; Kölsch, Kathrin; Halajda, Beata; Eichler, Hermann; Wagenpfeil, Stefan; Roemer, Klaus; Glanemann, Matthias

    2016-01-01

    Recent findings strongly support a role for small regulatory RNAs in the regulation of human lifespan yet little information exists about the precise underlying mechanisms. Although extensive studies on model organisms have indicated that reduced activity of the nutrient response pathway, for example as a result of dietary restriction, can extend lifespan through the suppression of the protein kinase mechanistic target of rapamycin (mTOR), it still is subject of debate whether this mechanism is operative in humans as well. Here, we present findings indicating that human microRNA (miR)-496 targets 2 sites within the human mTOR 3'UTR. Coexpression of miR-496 with different fusion transcripts, consisting of the luciferase transcript and either wild-type mTOR 3'UTR or mTOR 3'UTR transcript with the miR-496 binding sites singly or combined mutated, confirmed this prediction and revealed cooperativity between the 2 binding sites. miR-496 reduced the mTOR protein level in HeLa-K cells, and the levels of miR-496 and mTOR protein were inversely correlated in Peripheral Blood Mononuclear Cells (PBMC), with old individuals (n = 40) harbouring high levels of miR-496 relative to young individuals (n = 40). Together, these findings point to the possibility that miR-496 is involved in the regulation of human aging through the control of mTOR. PMID:27097372

  17. Targeted inhibition of mTOR signaling improves sensitivity of esophageal squamous cell carcinoma cells to cisplatin.

    PubMed

    Hou, Guiqin; Yang, Shuai; Zhou, Yuanyuan; Wang, Cong; Zhao, Wen; Lu, Zhaoming

    2014-01-01

    mTOR is an evolutionarily conserved serine-threonine kinase with a central role in cell growth, invasion, and metastasis of tumors, and is activated in many cancers. The aims of this study were to investigate the expression of mTOR in ESCC tissues and its relationship with progression of ESCC and measure the changes of sensitivity of ESCC cells to cisplatin after cells were treated with mTOR siRNA by WST-8 assays, TUNEL, RT-PCR, and western blots in vitro and in vivo. The results showed that the expression of mTOR was higher in ESCC specimens than that in normal esophageal tissues and its expression was closely correlated with the TNM stage of ESCC. mTOR siRNA significantly increased the sensitivity of the EC9706 cells to cisplatin at proliferation in vitro and in vivo. The growth of ESCC xenografts was significantly inhibited by mTOR siRNA or cisplatin, and the cell number of apoptosis was obviously increased after xenografts were treated with mTOR siRNA or cisplatin alone, especially when mTOR siRNA combined with cisplatin. The present study demonstrates that the expression of mTOR has important clinical significance and inhibition of mTOR pathway by mTOR siRNA can improve the sensitivity of ESCC cells to cisplatin.

  18. The Synergistic Effect of Everolimus and Chloroquine on Endothelial Cell Number Reduction Is Paralleled by Increased Apoptosis and Reduced Autophagy Occurrence

    PubMed Central

    Grimaldi, Anna; Balestrieri, Maria Luisa; D'Onofrio, Nunzia; Di Domenico, Gilda; Nocera, Cosimo; Lamberti, Monica; Tonini, Giuseppe; Zoccoli, Alice; Santini, Daniele; Caraglia, Michele; Pantano, Francesco

    2013-01-01

    Endothelial Progenitor Cells (EPCs), a minor subpopulation of the mononuclear cell fraction in peripheral blood, play a critical role in cancer development as they contribute to angiogenesis-mediated pathological neovascularization. In response to tumor cytokines, including VEGF, EPCs mobilize from the bone marrow into the peripheral circulation and move to the tumor bed where they incorporate into sprouting neovessels. In the present study, we evaluated the effects of everolimus (Afinitor, Novartis), a rapamycin analogue, alone or in combination with chloroquine, a 4-alkylamino substituted quinoline family member, one of the autophagy inhibitors, on EPCs biological functions. We found that either everolimus or chloroquine induce growth inhibition on EPCs in a dose-dependent manner after 72 h from the beginning of incubation. The combined administration of the two drugs to EPC was synergistic in inducing growth inhibition; in details, the maximal pharmacological synergism between everolimus and chloroquine in inducing growth inhibition on EPCs cells was recorded when chloroquine was administered 24 h before everolimus. Moreover, we have studied the mechanisms of cell death induced by the two agents alone or in combination on EPCs and we have found that the synergistic effect of combination on EPC growth inhibition was paralleled by increased apoptosis induction and reduced autophagy. These effects occurred together with biochemical features that are typical of reduced autophagic death such as increased co-immunoprecipitation between Beclin 1 and Bcl-2. Chloroquine antagonized the inhibition of the activity of Akt→4EBP1 axis mediated by everolimus and at the same time it blocked the feed-back activation of Erk-1/2 induced by RAD in EPCs. These data suggest a new strategy in order to block angiogenesis in tumours in which this process plays a key role in both the sustainment and spreading of cancer cells. PMID:24244540

  19. Docosahexaenoic Acid Sensitizes Leukemia Lymphocytes to Barasertib and Everolimus by ROS-dependent Mechanism Without Affecting the Level of ROS and Viability of Normal Lymphocytes.

    PubMed

    Zhelev, Zhivko; Ivanova, Donika; Lazarova, Desislava; Aoki, Ichio; Bakalova, Rumiana; Saga, Tsuneo

    2016-04-01

    The aim of the present study was: (i) to investigate the possibility of sensitizing leukemia lymphocytes to anticancer drugs using docosahexaenoic acid (DHA); (ii) to find combinations with synergistic cytotoxic effect on leukemia lymphocytes, without or with only very low cytotoxicity towards normal lymphocytes; (iii) and to clarify the role of reactive oxygen species (ROS) in the induction of apoptosis and cytotoxicity by such combinations. The study covered 15 anticancer drugs, conventional and new-generation. Well-expressed synergistic cytotoxic effects were observed after treatment of leukemia lymphocytes (Jurkat) with DHA in combination with: barasertib, lonafarnib, everolimus, and palbociclib. We selected two synergistic combinations, DHA with everolimus or barasertib, and investigated their effects on viability of normal lymphocytes, as well as on the production of ROS and induction of apoptosis in both cell lines (leukemia and normal). At the selected concentrations, DHA, everolimus and barasertib (applied separately) were cytotoxic towards leukemia lymphocytes, but not normal lymphocytes. In leukemia cells, the cytotoxicity of combinations was accompanied by strong induction of apoptosis and production of ROS. In normal lymphocytes, drugs alone and in combination with DHA did not affect the level of ROS and did not induce apoptosis. To our knowledge, the present study is the first to report synergistic ROS-dependent cytotoxicity between DHA and new-generation anticancer drugs, such as everolimus and barasertib, that is cancer cell-specific (particularly for acute lymphoblastic leukemia cells Jurkat). These combinations are harmless to normal lymphocytes and do not induce abnormal production of ROS in these cells. The data suggest that DHA could be used as a supplementary component in anticancer chemotherapy, allowing therapeutic doses of everolimus and barasertib to be reduced, minimizing their side-effects. PMID:27069145

  20. Biodegradable-Polymer Biolimus-Eluting Stents versus Durable-Polymer Everolimus-Eluting Stents at One-Year Follow-Up: A Registry-Based Cohort Study.

    PubMed

    Parsa, Ehsan; Saroukhani, Sepideh; Majlessi, Fereshteh; Poorhosseini, Hamidreza; Lofti-Tokaldany, Masoumeh; Jalali, Arash; Salarifar, Mojtaba; Nematipour, Ebrahim; Alidoosti, Mohammad; Aghajani, Hassan; Amirzadegan, Alireza; Kassaian, Seyed Ebrahim

    2016-04-01

    We compared outcomes of percutaneous coronary intervention patients who received biodegradable-polymer biolimus-eluting stents with those who received durable-polymer everolimus-eluting stents. At Tehran Heart Center, we performed a retrospective analysis of the data from January 2007 through December 2011 on 3,270 consecutive patients with coronary artery disease who underwent percutaneous coronary intervention with the biodegradable-polymer biolimus-eluting stent or the durable-polymer everolimus-eluting stent. We excluded patients with histories of coronary artery bypass grafting or percutaneous coronary intervention, acute ST-segment-elevation myocardial infarction, or the implantation of 2 different stent types. Patients were monitored for 12 months. The primary endpoint was a major adverse cardiac event, defined as a composite of death, nonfatal myocardial infarction, and target-vessel and target-lesion revascularization. Durable-polymer everolimus-eluting stents were implanted in 2,648 (81%) and biodegradable-polymer biolimus-eluting stents in 622 (19%) of the study population. There was no significant difference between the 2 groups (2.7% vs 2.7%; P=0.984) in the incidence of major adverse cardiac events. The cumulative adjusted probability of major adverse cardiac events in the biodegradable-polymer biolimus-eluting stent group did not differ from that of such events in the durable-polymer everolimus-eluting stent group (hazard ratio=0.768; 95% confidence interval, 0.421-1.44; P=0.388). We conclude that in our patients the biodegradable-polymer biolimus-eluting stent was as effective and safe, during the 12-month follow-up period, as was the durable-polymer everolimus-eluting stent.

  1. Caffeine affects the biological responses of human hematopoietic cells of myeloid lineage via downregulation of the mTOR pathway and xanthine oxidase activity.

    PubMed

    Gibbs, Bernhard F; Gonçalves Silva, Isabel; Prokhorov, Alexandr; Abooali, Maryam; Yasinska, Inna M; Casely-Hayford, Maxwell A; Berger, Steffen M; Fasler-Kan, Elizaveta; Sumbayev, Vadim V

    2015-10-01

    Correction of human myeloid cell function is crucial for the prevention of inflammatory and allergic reactions as well as leukaemia progression. Caffeine, a naturally occurring food component, is known to display anti-inflammatory effects which have previously been ascribed largely to its inhibitory actions on phosphodiesterase. However, more recent studies suggest an additional role in affecting the activity of the mammalian target of rapamycin (mTOR), a master regulator of myeloid cell translational pathways, although detailed molecular events underlying its mode of action have not been elucidated. Here, we report the cellular uptake of caffeine, without metabolisation, by healthy and malignant hematopoietic myeloid cells including monocytes, basophils and primary acute myeloid leukaemia mononuclear blasts. Unmodified caffeine downregulated mTOR signalling, which affected glycolysis and the release of pro-inflammatory/pro-angiogenic cytokines as well as other inflammatory mediators. In monocytes, the effects of caffeine were potentiated by its ability to inhibit xanthine oxidase, an enzyme which plays a central role in human purine catabolism by generating uric acid. In basophils, caffeine also increased intracellular cyclic adenosine monophosphate (cAMP) levels which further enhanced its inhibitory action on mTOR. These results demonstrate an important mode of pharmacological action of caffeine with potentially wide-ranging therapeutic impact for treating non-infectious disorders of the human immune system, where it could be applied directly to inflammatory cells.

  2. A germline MTOR mutation in Aboriginal Australian siblings with intellectual disability, dysmorphism, macrocephaly, and small thoraces.

    PubMed

    Baynam, Gareth; Overkov, Angela; Davis, Mark; Mina, Kym; Schofield, Lyn; Allcock, Richard; Laing, Nigel; Cook, Matthew; Dawkins, Hugh; Goldblatt, Jack

    2015-07-01

    We report on three Aboriginal Australian siblings with a unique phenotype which overlaps with known megalencephaly syndromes and RASopathies, including Costello syndrome. A gain-of-function mutation in MTOR was identified and represents the first reported human condition due to a germline, familial MTOR mutation. We describe the findings in this family to highlight that (i) the path to determination of pathogenicity was confounded by the lack of genomic reference data for Australian Aboriginals and that (ii) the disease biology, functional analyses in this family, and studies on the tuberous sclerosis complex support consideration of an mTOR inhibitor as a therapeutic agent. PMID:25851998

  3. [Signaling pathways mTOR and AKT in epilepsy].

    PubMed

    Romero-Leguizamon, C R; Ramirez-Latorre, J A; Mora-Munoz, L; Guerrero-Naranjo, A

    2016-07-01

    Introduccion. La via de señalizacion AKT/mTOR es un eje central en la regulacion celular, especialmente en las enfermedades neurologicas. En la epilepsia, se ha evidenciado su alteracion dentro de su proceso fisiopatologico. Sin embargo, aun no se han descrito todos los mecanismos de estas rutas de señalizacion, las cuales podrian abrir la puerta hacia nuevas investigaciones y estrategias terapeuticas, que finalmente permitan desarrollar tratamientos efectivos en enfermedades neurologicas como la epilepsia. Objetivo. Revisar las asociaciones existentes entre las rutas de señalizacion intracelular de mTOR y AKT en la fisiopatologia de la epilepsia. Desarrollo. La epilepsia es una enfermedad neurologica con un alto impacto epidemiologico en el mundo, por lo cual es de sumo interes la investigacion de los componentes fisiopatologicos que puedan generar nuevos tratamientos farmacologicos. En esta busqueda se han involucrado diferentes rutas de señalizacion intracelular en neuronas, como determinantes epileptogenos. Los avances en esta materia han permitido incluso la implementacion de nuevas estrategias terapeuticas exitosas y que abren el camino hacia nuevas investigaciones. Conclusiones. Mejorar los conocimientos respecto al papel fisiopatologico de la via de señalizacion mTOR/AKT en la epilepsia permite plantear nuevas investigaciones que ofrezcan nuevas alternativas terapeuticas para el tratamiento de la enfermedad. El uso de inhibidores de mTOR ha surgido en los ultimos años como una alternativa eficaz en el tratamiento de algunos tipos de epilepsias, pero es evidente la necesidad de seguir en la busqueda de nuevas terapias farmacologicas involucradas en estas vias de señalizacion.

  4. Place of mTOR inhibitors in management of BKV infection after kidney transplantation

    PubMed Central

    Jouve, Thomas; Rostaing, Lionel; Malvezzi, Paolo

    2016-01-01

    Context: BK virus (BKV) viremia and BKV-associated nephropathy (BKVAN) have become a serious nuisance to kidney transplant (KT) patients since the mid-nineties, when the incidence of this disease has increased significantly. Evidence Acquisition: Directory of open access journals (DOAJ), EMBASE, Google Scholar, PubMed, EBSCO, and Web of Science have been searched. Results: Many hypothesis have been made as to why this phenomenon has developed; it is of general opinion that a more potent immunosuppression is at the core of the problem. The use of the association of tacrolimus (TAC) with mycophenolic acid (MPA) has gained momentum in the same years as the increase in BKV viremia incidence making it seem to be the most likely culprit. m-TOR inhibitors (m-TORIs) have been shown to have antiviral properties in vitro and this fact has encouraged different transplant teams to use these agents when confronted with BKV infection (viremia or nephropathy). However, the results are mitigated. There had been conflicting results for example when converting from TAC-to sirolimus-based immunosuppression in the setting of established BKVAN. Conclusions: In order to prevent BKV infection we have to minimize to some extent immunosuppression, but it is not always possible, e.g. in high immunological risk patients. Conversely, we could use m-TORIs associated with low-dose calcineurin inhibitors (CNIs). This could be actually the key to a safe immunosuppression regimen both from the immunological stand point and from the viral one. PMID:27047803

  5. Resveratrol as a novel treatment for diseases with mTOR pathway hyperactivation.

    PubMed

    Alayev, Anya; Berger, Sara Malka; Holz, Marina K

    2015-08-01

    The mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway is hyperactivated in a variety of cancers and tumor syndromes. Therefore, mTORC1 inhibitors are being actively investigated for treatment of neoplasms. The concern with the monotherapy use of mTORC1 inhibitors, such as rapamycin, is that they cause upregulation of autophagy, a cell survival mechanism, and suppress the negative feedback loop to the oncogene Akt. In turn, Akt promotes cell survival, causing the therapy to be partially effective, but relapse occurs upon cessation of treatment. In this review, we describe the current literature on resveratrol as well as our work, which uses rapamycin in combination with resveratrol. We found that this combination treatment efficiently blocked upregulation of autophagy and restored inhibition of Akt in different cancer and tumor models. Interestingly, the combination of rapamycin and resveratrol selectively promoted apoptosis of cells with mTOR pathway hyperactivation. Moreover, this combination prevented tumor growth and lung metastasis when tested in mouse models. Finally, mass spectrometry-based identification of cellular targets of resveratrol provided mechanistic insight into the mode of action of resveratrol. The addition of resveratrol to rapamycin treatment may be a promising option for selective and targeted therapy for diseases with mTORC1 hyperactivation. PMID:26200935

  6. Antidepressant action of ketamine via mTOR is mediated by inhibition of nitrergic Rheb degradation.

    PubMed

    Harraz, M M; Tyagi, R; Cortés, P; Snyder, S H

    2016-03-01

    As traditional antidepressants act only after weeks/months, the discovery that ketamine, an antagonist of glutamate/N-methyl-D-aspartate (NMDA) receptors, elicits antidepressant actions in hours has been transformative. Its mechanism of action has been elusive, though enhanced mammalian target of rapamycin (mTOR) signaling is a major feature. We report a novel signaling pathway wherein NMDA receptor activation stimulates generation of nitric oxide (NO), which S-nitrosylates glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Nitrosylated GAPDH complexes with the ubiquitin-E3-ligase Siah1 and Rheb, a small G protein that activates mTOR. Siah1 degrades Rheb leading to reduced mTOR signaling, while ketamine, conversely, stabilizes Rheb that enhances mTOR signaling. Drugs selectively targeting components of this pathway may offer novel approaches to the treatment of depression. PMID:26782056

  7. Adapting the Stress Response: Viral Subversion of the mTOR Signaling Pathway

    PubMed Central

    Le Sage, Valerie; Cinti, Alessandro; Amorim, Raquel; Mouland, Andrew J.

    2016-01-01

    The mammalian target of rapamycin (mTOR) is a central regulator of gene expression, translation and various metabolic processes. Multiple extracellular (growth factors) and intracellular (energy status) molecular signals as well as a variety of stressors are integrated into the mTOR pathway. Viral infection is a significant stress that can activate, reduce or even suppress the mTOR signaling pathway. Consequently, viruses have evolved a plethora of different mechanisms to attack and co-opt the mTOR pathway in order to make the host cell a hospitable environment for replication. A more comprehensive knowledge of different viral interactions may provide fruitful targets for new antiviral drugs. PMID:27231932

  8. mTOR, metabolism, and the regulation of T-cell differentiation and function

    PubMed Central

    Waickman, Adam T; Powell, Jonathan D.

    2012-01-01

    Summary Upon antigen recognition, naive T cells undergo rapid expansion and activation. The energy requirements for this expansion are formidable, and T-cell activation is accompanied by dramatic changes in cellular metabolism. Furthermore, the outcome of antigen engagement is guided by multiple cues derived from the immune microenvironment. Mammalian target of rapamycin (mTOR) is emerging as a central integrator of these signals playing a critical role in driving T-cell differentiation and function. Indeed, multiple metabolic programs are controlled by mTOR signaling. In this review, we discuss the role of mTOR in regulating metabolism and how these pathways intersect with the ability of mTOR to integrate cues that guide the outcome of T-cell receptor engagement. PMID:22889214

  9. Antidepressant action of ketamine via mTOR is mediated by inhibition of nitrergic Rheb degradation

    PubMed Central

    Harraz, Maged M.; Tyagi, Richa; Cortés, Pedro; Snyder, Solomon H.

    2016-01-01

    As traditional antidepressants act only after weeks/months, the discovery that ketamine, an antagonist of glutamate/NMDA receptors, elicits antidepressant actions in hours has been transformative. Its mechanism of action has been elusive, though enhanced mTOR signaling is a major feature. We report a novel signaling pathway wherein NMDA receptor activation stimulates generation of nitric oxide (NO), which S-nitrosylates glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Nitrosylated GAPDH complexes with the ubiquitin-E3-ligase Siah1 and Rheb, a small G protein that activates mTOR. Siah1 degrades Rheb leading to reduced mTOR signaling, while ketamine, conversely, stabilizes Rheb which enhances mTOR signaling. Drugs selectively targeting components of this pathway may offer novel approaches to the treatment of depression. PMID:26782056

  10. mTOR Regulation of Lymphoid Cells in Immunity to Pathogens.

    PubMed

    Keating, Rachael; McGargill, Maureen Ann

    2016-01-01

    Immunity to pathogens exists as a fine balance between promoting activation and expansion of effector cells, while simultaneously limiting normal and aberrant responses. These seemingly opposing functions are kept in check by immune regulators. The mechanistic target of rapamycin (mTOR) is a serine/threonine kinase that senses nutrient availability and, in turn, regulates cell metabolism, growth, and survival accordingly. mTOR plays a pivotal role in facilitating immune defense against invading pathogens by regulating the differentiation, activation, and effector functions of lymphoid cells. Here, we focus on the emerging and sometimes contradictory roles of mTOR in orchestrating lymphoid cell-mediated host immune responses to pathogens. A thorough understanding of how mTOR impacts lymphoid cells in pathogen defense will provide the necessary base for developing therapeutic interventions for infectious diseases. PMID:27242787

  11. mTOR Regulation of Lymphoid Cells in Immunity to Pathogens

    PubMed Central

    Keating, Rachael; McGargill, Maureen Ann

    2016-01-01

    Immunity to pathogens exists as a fine balance between promoting activation and expansion of effector cells, while simultaneously limiting normal and aberrant responses. These seemingly opposing functions are kept in check by immune regulators. The mechanistic target of rapamycin (mTOR) is a serine/threonine kinase that senses nutrient availability and, in turn, regulates cell metabolism, growth, and survival accordingly. mTOR plays a pivotal role in facilitating immune defense against invading pathogens by regulating the differentiation, activation, and effector functions of lymphoid cells. Here, we focus on the emerging and sometimes contradictory roles of mTOR in orchestrating lymphoid cell-mediated host immune responses to pathogens. A thorough understanding of how mTOR impacts lymphoid cells in pathogen defense will provide the necessary base for developing therapeutic interventions for infectious diseases. PMID:27242787

  12. DEPTOR-related mTOR suppression is involved in metformin's anti-cancer action in human liver cancer cells

    SciTech Connect

    Obara, Akio; Fujita, Yoshihito; Abudukadier, Abulizi; Fukushima, Toru; Oguri, Yasuo; Ogura, Masahito; Harashima, Shin-ichi; Hosokawa, Masaya; Inagaki, Nobuya

    2015-05-15

    Metformin, one of the most commonly used drugs for patients with type 2 diabetes, recently has received much attention regarding its anti-cancer action. It is thought that the suppression of mTOR signaling is involved in metformin's anti-cancer action. Although liver cancer is one of the most responsive types of cancer for reduction of incidence by metformin, the molecular mechanism of the suppression of mTOR in liver remains unknown. In this study, we investigated the mechanism of the suppressing effect of metformin on mTOR signaling and cell proliferation using human liver cancer cells. Metformin suppressed phosphorylation of p70-S6 kinase, and ribosome protein S6, downstream targets of mTOR, and suppressed cell proliferation. We found that DEPTOR, an endogenous substrate of mTOR suppression, is involved in the suppressing effect of metformin on mTOR signaling and cell proliferation in human liver cancer cells. Metformin increases the protein levels of DEPTOR, intensifies binding to mTOR, and exerts a suppressing effect on mTOR signaling. This increasing effect of DEPTOR by metformin is regulated by the proteasome degradation system; the suppressing effect of metformin on mTOR signaling and cell proliferation is in a DEPTOR-dependent manner. Furthermore, metformin exerts a suppressing effect on proteasome activity, DEPTOR-related mTOR signaling, and cell proliferation in an AMPK-dependent manner. We conclude that DEPTOR-related mTOR suppression is involved in metformin's anti-cancer action in liver, and could be a novel target for anti-cancer therapy. - Highlights: • We elucidated a novel pathway of metformin's anti-cancer action in HCC cells. • DEPTOR is involved in the suppressing effect of metformin on mTOR signaling. • Metformin increases DEPTOR protein levels via suppression of proteasome activity. • DEPTOR-related mTOR suppression is involved in metformin's anti-cancer action.

  13. mTOR controls mitochondrial oxidative function through a YY1-PGC-1alpha transcriptional complex.

    PubMed

    Cunningham, John T; Rodgers, Joseph T; Arlow, Daniel H; Vazquez, Francisca; Mootha, Vamsi K; Puigserver, Pere

    2007-11-29

    Transcriptional complexes that contain peroxisome-proliferator-activated receptor coactivator (PGC)-1alpha control mitochondrial oxidative function to maintain energy homeostasis in response to nutrient and hormonal signals. An important component in the energy and nutrient pathways is mammalian target of rapamycin (mTOR), a kinase that regulates cell growth, size and survival. However, it is unknown whether and how mTOR controls mitochondrial oxidative activities. Here we show that mTOR is necessary for the maintenance of mitochondrial oxidative function. In skeletal muscle tissues and cells, the mTOR inhibitor rapamycin decreased the gene expression of the mitochondrial transcriptional regulators PGC-1alpha, oestrogen-related receptor alpha and nuclear respiratory factors, resulting in a decrease in mitochondrial gene expression and oxygen consumption. Using computational genomics, we identified the transcription factor yin-yang 1 (YY1) as a common target of mTOR and PGC-1alpha. Knockdown of YY1 caused a significant decrease in mitochondrial gene expression and in respiration, and YY1 was required for rapamycin-dependent repression of those genes. Moreover, mTOR and raptor interacted with YY1, and inhibition of mTOR resulted in a failure of YY1 to interact with and be coactivated by PGC-1alpha. We have therefore identified a mechanism by which a nutrient sensor (mTOR) balances energy metabolism by means of the transcriptional control of mitochondrial oxidative function. These results have important implications for our understanding of how these pathways might be altered in metabolic diseases and cancer. PMID:18046414

  14. YAP enters the mTOR pathway to promote tuberous sclerosis complex

    PubMed Central

    Liang, Ning; Pende, Mario

    2015-01-01

    Mutations in tuberous sclerosis complex 1 (TSC1) or TSC2 predispose to angiomyolipomas and lymphangioleiomyomatosis in a mTOR-dependent manner. In these mesenchymal lesions, mTOR suppresses macroautophagy-mediated lysosomal degradation of YAP, which is a transcriptional coactivator of Hippo pathway and is required for the tumorigenesis of TSC. Therapeutic applications for TSC and other diseases with dysregulated mTOR activity can be envisaged. PMID:27308518

  15. TNFAIP3 promotes survival of CD4 T cells by restricting MTOR and promoting autophagy.

    PubMed

    Matsuzawa, Yu; Oshima, Shigeru; Takahara, Masahiro; Maeyashiki, Chiaki; Nemoto, Yasuhiro; Kobayashi, Masanori; Nibe, Yoichi; Nozaki, Kengo; Nagaishi, Takashi; Okamoto, Ryuichi; Tsuchiya, Kiichiro; Nakamura, Tetsuya; Ma, Averil; Watanabe, Mamoru

    2015-01-01

    Autophagy plays important roles in metabolism, differentiation, and survival in T cells. TNFAIP3/A20 is a ubiquitin-editing enzyme that is thought to be a negative regulator of autophagy in cell lines. However, the role of TNFAIP3 in autophagy remains unclear. To determine whether TNFAIP3 regulates autophagy in CD4 T cells, we first analyzed Tnfaip3-deficient naïve CD4 T cells in vitro. We demonstrated that Tnfaip3-deficient CD4 T cells exhibited reduced MAP1LC3/LC3 (microtubule-associated protein 1 light chain 3) puncta formation, increased mitochondrial content, and exaggerated reactive oxygen species (ROS) production. These results indicate that TNFAIP3 promotes autophagy after T cell receptor (TCR) stimulation in CD4 T cells. We then investigated the mechanism by which TNFAIP3 promotes autophagy signaling. We found that TNFAIP3 bound to the MTOR (mechanistic target of rapamycin) complex and that Tnfaip3-deficient cells displayed enhanced ubiquitination of the MTOR complex and MTOR activity. To confirm the effects of enhanced MTOR activity in Tnfaip3-deficient cells, we analyzed cell survival following treatment with Torin1, an MTOR inhibitor. Tnfaip3-deficient CD4 T cells exhibited fewer cell numbers than the control cells in vitro and in vivo. In addition, the impaired survival of Tnfaip3-deficient cells was ameliorated with Torin1 treatment in vitro and in vivo. The effect of Torin1 was abolished by Atg5 deficiency. Thus, enhanced MTOR activity regulates the survival of Tnfaip3-deficient CD4 T cells. Taken together, our findings illustrate that TNFAIP3 restricts MTOR signaling and promotes autophagy, providing new insight into the manner in which MTOR and autophagy regulate survival in CD4 T cells.

  16. TNFAIP3 promotes survival of CD4 T cells by restricting MTOR and promoting autophagy

    PubMed Central

    Matsuzawa, Yu; Oshima, Shigeru; Takahara, Masahiro; Maeyashiki, Chiaki; Nemoto, Yasuhiro; Kobayashi, Masanori; Nibe, Yoichi; Nozaki, Kengo; Nagaishi, Takashi; Okamoto, Ryuichi; Tsuchiya, Kiichiro; Nakamura, Tetsuya; Ma, Averil; Watanabe, Mamoru

    2015-01-01

    Autophagy plays important roles in metabolism, differentiation, and survival in T cells. TNFAIP3/A20 is a ubiquitin-editing enzyme that is thought to be a negative regulator of autophagy in cell lines. However, the role of TNFAIP3 in autophagy remains unclear. To determine whether TNFAIP3 regulates autophagy in CD4 T cells, we first analyzed Tnfaip3-deficient naïve CD4 T cells in vitro. We demonstrated that Tnfaip3-deficient CD4 T cells exhibited reduced MAP1LC3/LC3 (microtubule-associated protein 1 light chain 3) puncta formation, increased mitochondrial content, and exaggerated reactive oxygen species (ROS) production. These results indicate that TNFAIP3 promotes autophagy after T cell receptor (TCR) stimulation in CD4 T cells. We then investigated the mechanism by which TNFAIP3 promotes autophagy signaling. We found that TNFAIP3 bound to the MTOR (mechanistic target of rapamycin) complex and that Tnfaip3-deficient cells displayed enhanced ubiquitination of the MTOR complex and MTOR activity. To confirm the effects of enhanced MTOR activity in Tnfaip3-deficient cells, we analyzed cell survival following treatment with Torin1, an MTOR inhibitor. Tnfaip3-deficient CD4 T cells exhibited fewer cell numbers than the control cells in vitro and in vivo. In addition, the impaired survival of Tnfaip3-deficient cells was ameliorated with Torin1 treatment in vitro and in vivo. The effect of Torin1 was abolished by Atg5 deficiency. Thus, enhanced MTOR activity regulates the survival of Tnfaip3-deficient CD4 T cells. Taken together, our findings illustrate that TNFAIP3 restricts MTOR signaling and promotes autophagy, providing new insight into the manner in which MTOR and autophagy regulate survival in CD4 T cells. PMID:26043155

  17. Glucocorticoids modulate the mTOR pathway in the hippocampus: differential effects depending on stress history.

    PubMed

    Polman, J Annelies E; Hunter, Richard G; Speksnijder, Niels; van den Oever, Jessica M E; Korobko, Oksana B; McEwen, Bruce S; de Kloet, E Ronald; Datson, Nicole A

    2012-09-01

    Glucocorticoid (GC) hormones, released by the adrenals in response to stress, are key regulators of neuronal plasticity. In the brain, the hippocampus is a major target of GC, with abundant expression of the GC receptor. GC differentially affect the hippocampal transcriptome and consequently neuronal plasticity in a subregion-specific manner, with consequences for hippocampal information flow and memory formation. Here, we show that GC directly affect the mammalian target of rapamycin (mTOR) signaling pathway, which plays a central role in translational control and has long-lasting effects on the plasticity of specific brain circuits. We demonstrate that regulators of the mTOR pathway, DNA damage-induced transcript (DDIT)4 and FK506-binding protein 51 are transcriptionally up-regulated by an acute GC challenge in the dentate gyrus (DG) subregion of the rat hippocampus, most likely via a GC-response element-driven mechanism. Furthermore, two other mTOR pathway members, the mTOR regulator DDIT4-like and the mTOR target DDIT3, are down-regulated by GC in the rat DG. Interestingly, the GC responsiveness of DDIT4 and DDIT3 was lost in animals with a recent history of chronic stress. Basal hippocampal mTOR protein levels were higher in animals exposed to chronic stress than in controls. Moreover, an acute GC challenge significantly reduced mTOR protein levels in the hippocampus of animals with a chronic stress history but not in unstressed controls. Based on these findings, we propose that direct regulation of the mTOR pathway by GC represents an important mechanism regulating neuronal plasticity in the rat DG, which changes after exposure to chronic stress.

  18. Periostin Responds to Mechanical Stress and Tension by Activating the MTOR Signaling Pathway

    PubMed Central

    Rosselli-Murai, Luciana K.; Galindo-Moreno, Pablo; Padial-Molina, Miguel; Volk, Sarah L.; Murai, Marcelo J.; Rios, Hector F.; Squarize, Cristiane H.; Castilho, Rogerio M.

    2013-01-01

    Current knowledge about Periostin biology has expanded from its recognized functions in embryogenesis and bone metabolism to its roles in tissue repair and remodeling and its clinical implications in cancer. Emerging evidence suggests that Periostin plays a critical role in the mechanism of wound healing; however, the paracrine effect of Periostin in epithelial cell biology is still poorly understood. We found that epithelial cells are capable of producing endogenous Periostin that, unlike mesenchymal cell, cannot be secreted. Epithelial cells responded to Periostin paracrine stimuli by enhancing cellular migration and proliferation and by activating the mTOR signaling pathway. Interestingly, biomechanical stimulation of epithelial cells, which simulates tension forces that occur during initial steps of tissue healing, induced Periostin production and mTOR activation. The molecular association of Periostin and mTOR signaling was further dissected by administering rapamycin, a selective pharmacological inhibitor of mTOR, and by disruption of Raptor and Rictor scaffold proteins implicated in the regulation of mTORC1 and mTORC2 complex assembly. Both strategies resulted in ablation of Periostin-induced mitogenic and migratory activity. These results indicate that Periostin-induced epithelial migration and proliferation requires mTOR signaling. Collectively, our findings identify Periostin as a mechanical stress responsive molecule that is primarily secreted by fibroblasts during wound healing and expressed endogenously in epithelial cells resulting in the control of cellular physiology through a mechanism mediated by the mTOR signaling cascade. PMID:24349533

  19. Hyperactive mTOR pathway promotes lymphoproliferation and abnormal differentiation in autoimmune lymphoproliferative syndrome.

    PubMed

    Völkl, Simon; Rensing-Ehl, Anne; Allgäuer, Andrea; Schreiner, Elisabeth; Lorenz, Myriam Ricarda; Rohr, Jan; Klemann, Christian; Fuchs, Ilka; Schuster, Volker; von Bueren, André O; Naumann-Bartsch, Nora; Gambineri, Eleonora; Siepermann, Kathrin; Kobbe, Robin; Nathrath, Michaela; Arkwright, Peter D; Miano, Maurizio; Stachel, Klaus-Daniel; Metzler, Markus; Schwarz, Klaus; Kremer, Anita N; Speckmann, Carsten; Ehl, Stephan; Mackensen, Andreas

    2016-07-14

    Autoimmune lymphoproliferative syndrome (ALPS) is a human disorder characterized by defective Fas signaling, resulting in chronic benign lymphoproliferation and accumulation of TCRαβ(+) CD4(-) CD8(-) double-negative T (DNT) cells. Although their phenotype resembles that of terminally differentiated or exhausted T cells, lack of KLRG1, high eomesodermin, and marginal T-bet expression point instead to a long-lived memory state with potent proliferative capacity. Here we show that despite their terminally differentiated phenotype, human ALPS DNT cells exhibit substantial mitotic activity in vivo. Notably, hyperproliferation of ALPS DNT cells is associated with increased basal and activation-induced phosphorylation of serine-threonine kinases Akt and mechanistic target of rapamycin (mTOR). The mTOR inhibitor rapamycin abrogated survival and proliferation of ALPS DNT cells, but not of CD4(+) or CD8(+) T cells in vitro. In vivo, mTOR inhibition reduced proliferation and abnormal differentiation by DNT cells. Importantly, increased mitotic activity and hyperactive mTOR signaling was also observed in recently defined CD4(+) or CD8(+) precursor DNT cells, and mTOR inhibition specifically reduced these cells in vivo, indicating abnormal programming of Fas-deficient T cells before the DNT stage. Thus, our results identify the mTOR pathway as a major regulator of lymphoproliferation and aberrant differentiation in ALPS.

  20. mTOR inhibition sensitizes ONC201-induced anti-colorectal cancer cell activity.

    PubMed

    Jin, Zhe-Zhu; Wang, Wei; Fang, Di-Long; Jin, Yong-Jun

    2016-09-30

    We here tested the anti-colorectal cancer (CRC) activity by a first-in-class small molecule TRAIL inducer ONC201. The potential effect of mTOR on ONC201's actions was also examined. ONC201 induced moderate cytotoxicity against CRC cell lines (HT-29, HCT-116 and DLD-1) and primary human CRC cells. Significantly, AZD-8055, a mTOR kinase inhibitor, sensitized ONC201-induced cytotoxicity in CRC cells. Meanwhile, ONC201-induced TRAIL/death receptor-5 (DR-5) expression, caspase-8 activation and CRC cell apoptosis were also potentiated with AZD-8055 co-treatment. Reversely, TRAIL sequestering antibody RIK-2 or the caspase-8 specific inhibitor z-IETD-fmk attenuated AZD-8055 plus ONC201-induced CRC cell death. Further, mTOR kinase-dead mutation (Asp-2338-Ala) or shRNA knockdown significantly sensitized ONC201's activity in CRC cells, leading to profound cell death and apoptosis. On the other hand, expression of a constitutively-active S6K1 (T389E) attenuated ONC201-induced CRC cell apoptosis. For the mechanism study, we showed that ONC201 blocked Akt, but only slightly inhibited mTOR in CRC cells. Co-treatment with AZD-8055 also concurrently blocked mTOR activation. These results suggest that mTOR could be a primary resistance factor of ONC201 in CRC cells. PMID:27565731

  1. Dysfunction of the mTOR pathway is a risk factor for Alzheimer’s disease

    PubMed Central

    2013-01-01

    Background The development of disease-modifying therapies for Alzheimer’s disease is hampered by our lack of understanding of the early pathogenic mechanisms and the lack of early biomarkers and risk factors. We have documented the expression pattern of mTOR regulated genes in the frontal cortex of Alzheimer’s disease patients. We have also examined the functional integrity of mTOR signaling in peripheral lymphocytes in Alzheimer’s disease patients relative to healthy controls. Results In the brain mTOR is seen to control molecular functions related to cell cycle regulation, cell death and several metabolic pathways. These downstream elements of the mTOR signaling cascade are deregulated in the brain of Alzheimer’s disease patients well before the development of pathology. This dysregulation of the mTOR downstream signaling cascade is not restricted to the brain but appears to be systemic and can be detected in peripheral lymphocytes as a reduced Rapamycin response. Conclusions The dysfunction of the signaling pathways downstream of mTOR may represent a risk factor for Alzheimer’s disease and is independent of the ApoE status of the patients. We have also identified the molecular substrates of the beneficial effects of Rapamycin on the nervous system. We believe that these results can further inform the development of clinical predictive tests for the risk of Alzheimer’s disease in patients with mild cognitive impairment. PMID:24252508

  2. Critical role for hypothalamic mTOR activity in energy balance

    PubMed Central

    Mori, Hiroyuki; Inoki, Ken; Münzberg, Heike; Opland, Darren; Faouzi, Miro; Villanueva, Eneida C.; Ikenoue, Tsuneo; Kwiatkowski, David; MacDougald, Ormond A; Myers, Martin G.; Guan, Kun-Liang

    2009-01-01

    Summary The mammalian target of Rapamycin (mTOR) promotes anabolic cellular processes in response to growth factors and metabolic cues. The TSC1 and TSC2 tumor suppressors are major upstream inhibitory regulators of mTOR signaling. Mice with Rip2/Cre-mediated deletion of Tsc1 (Rip-Tsc1cKO mice) developed hyperphagia and obesity, suggesting that hypothalamic disruption (for which Rip2/Cre is well known) of Tsc1 may dysregulate feeding circuits via mTOR activation. Indeed, Rip-Tsc1cKO mice displayed increased mTOR signaling and enlarged neuron cell size in a number of hypothalamic populations, including Pomc neurons. Furthermore, Tsc1 deletion with Pomc/Cre (Pomc-Tsc1cKO mice) resulted in dysregulation of Pomc neurons and hyperphagic obesity. Treatment with the mTOR inhibitor, rapamycin, ameliorated the hyperphagia, obesity, and the altered Pomc neuronal morphology in developing or adult Pomc-Tsc1cKO mice, and cessation of treatment reinstated these phenotypes. Thus, ongoing mTOR activation in Pomc neurons blocks the catabolic function of these neurons to promote nutrient intake and increased adiposity. PMID:19356717

  3. Mouse gene targeting reveals an essential role of mTOR in hematopoietic stem cell engraftment and hematopoiesis.

    PubMed

    Guo, Fukun; Zhang, Shuangmin; Grogg, Matthew; Cancelas, Jose A; Varney, Melinda E; Starczynowski, Daniel T; Du, Wei; Yang, Jun-Qi; Liu, Wei; Thomas, George; Kozma, Sara; Pang, Qishen; Zheng, Yi

    2013-09-01

    mTOR integrates signals from nutrients and growth factors to control protein synthesis, cell growth, and survival. Although mTOR has been established as a therapeutic target in hematologic malignancies, its physiological role in regulating hematopoiesis remains unclear. Here we show that conditional gene targeting of mTOR causes bone marrow failure and defects in multi-lineage hematopoiesis including myelopoiesis, erythropoiesis, thrombopoiesis, and lymphopoiesis. mTOR deficiency results in loss of quiescence of hematopoietic stem cells, leading to a transient increase but long-term exhaustion and defective engraftment of hematopoietic stem cells in lethally irradiated recipient mice. Furthermore, ablation of mTOR causes increased apoptosis in lineage-committed blood cells but not hematopoietic stem cells, indicating a differentiation stage-specific function. These results demonstrate that mTOR is essential for hematopoietic stem cell engraftment and multi-lineage hematopoiesis.

  4. Mouse gene targeting reveals an essential role of mTOR in hematopoietic stem cell engraftment and hematopoiesis

    PubMed Central

    Guo, Fukun; Zhang, Shuangmin; Grogg, Matthew; Cancelas, Jose A.; Varney, Melinda E.; Starczynowski, Daniel T.; Du, Wei; Yang, Jun-Qi; Liu, Wei; Thomas, George; Kozma, Sara; Pang, Qishen; Zheng, Yi

    2013-01-01

    mTOR integrates signals from nutrients and growth factors to control protein synthesis, cell growth, and survival. Although mTOR has been established as a therapeutic target in hematologic malignancies, its physiological role in regulating hematopoiesis remains unclear. Here we show that conditional gene targeting of mTOR causes bone marrow failure and defects in multi-lineage hematopoiesis including myelopoiesis, erythropoiesis, thrombopoiesis, and lymphopoiesis. mTOR deficiency results in loss of quiescence of hematopoietic stem cells, leading to a transient increase but long-term exhaustion and defective engraftment of hematopoietic stem cells in lethally irradiated recipient mice. Furthermore, ablation of mTOR causes increased apoptosis in lineage-committed blood cells but not hematopoietic stem cells, indicating a differentiation stage-specific function. These results demonstrate that mTOR is essential for hematopoietic stem cell engraftment and multi-lineage hematopoiesis. PMID:23716557

  5. mTOR plays critical roles in pancreatic cancer stem cells through specific and stemness-related functions

    NASA Astrophysics Data System (ADS)

    Matsubara, Shyuichiro; Ding, Qiang; Miyazaki, Yumi; Kuwahata, Taisaku; Tsukasa, Koichiro; Takao, Sonshin

    2013-11-01

    Pancreatic cancer is characterized by near-universal mutations in KRAS. The mammalian target of rapamycin (mTOR), which functions downstream of RAS, has divergent effects on stem cells. In the present study, we investigated the significance of the mTOR pathway in maintaining the properties of pancreatic cancer stem cells. The mTOR inhibitor, rapamycin, reduced the viability of CD133+ pancreatic cancer cells and sphere formation which is an index of self-renewal of stem-like cells, indicating that the mTOR pathway functions to maintain cancer stem-like cells. Further, rapamycin had different effects on CD133+ cells compared to cyclopamine which is an inhibitor of the Hedgehog pathway. Thus, the mTOR pathway has a distinct role although both pathways maintain pancreatic cancer stem cells. Therefore, mTOR might be a promising target to eliminate pancreatic cancer stem cells.

  6. Oral everolimus treatment in a preterm infant with multifocal inoperable cardiac rhabdomyoma associated with tuberous sclerosis complex and a structural heart defect.

    PubMed

    Mohamed, Ibrahim; Ethier, Guillaume; Goyer, Isabelle; Major, Philippe; Dahdah, Nagib

    2014-11-26

    Rhabdomyoma (RHM) is a benign cardiac tumour usually associated with tuberous sclerosis complex (TSC). Most RHMs are asymptomatic and regress spontaneously during the first years of life. Haemodynamically significant RHMs are classically treated with surgical excision. We present a case of a premature infant, born to a mother having TSC, with a prenatal diagnosis of pulmonary valve atresia and a large ventricular septal defect. Multiple cardiac RHMs were also present, including a large tumour affecting the right ventricular filling. Owing to the prematurity and low birth weight, the infant was inoperable. In this report, we describe our approach to pharmacologically reduce the RHM size using oral everolimus in preparation for a two-ventricle surgical repair of the structural cardiac defect. We also specifically describe the dose of everolimus that was used in this case to achieve therapeutic serum levels, which was seven times lower than the conventional dose applicable for older infants.

  7. Genetic and pharmacologic evidence that mTOR targeting outweighs mTORC1 inhibition as an antimyeloma strategy.

    PubMed

    Chen, Xi; Díaz-Rodríguez, Elena; Ocio, Enrique M; Paiva, Bruno; Mortensen, Deborah S; Lopez-Girona, Antonia; Chopra, Rajesh; Miguel, Jesús San; Pandiella, Atanasio

    2014-02-01

    The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that regulates cell growth, proliferation, metabolism, and cell survival, and plays those roles by forming two functionally distinct multiprotein complexes: mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Deregulation of the mTOR pathway has been found in different cancers, including multiple myeloma. Agents acting on mTORC1, such as rapamycin and derivatives, are being explored as antitumoral strategies. However, whether targeting mTOR would be a more effective antimyeloma strategy than exclusively acting on the mTORC1 branch remains to be established. In this report, we explored the activation status of mTOR routes in malignant plasma cells, and analyzed the contribution of mTOR and its two signaling branches to the proliferation of myeloma cells. Gene expression profiling demonstrated deregulation of mTOR pathway-related genes in myeloma plasma cells from patients. Activation of the mTOR pathway in myelomatous plasma cells was corroborated by flow cytometric analyses. RNA interference (RNAi) experiments indicated that mTORC1 predominated over mTORC2 in the control of myeloma cell proliferation. However, mTOR knockdown had a superior antiproliferative effect than acting only on mTORC1 or mTORC2. Pharmacologic studies corroborated that the neutralization of mTOR has a stronger antimyeloma effect than the individual inhibition of mTORC1 or mTORC2. Together, our data support the clinical development of agents that widely target mTOR, instead of agents, such as rapamycin or its derivatives, that solely act on mTORC1. PMID:24431075

  8. Lysosomal pH Plays a Key Role in Regulation of mTOR Activity in Osteoclasts.

    PubMed

    Hu, Yingwei; Carraro-Lacroix, Luciene R; Wang, Andrew; Owen, Celeste; Bajenova, Elena; Corey, Paul N; Brumell, John H; Voronov, Irina

    2016-02-01

    Mammalian target of rapamycin (mTOR) is a serine/threonine kinase involved in the regulation of cell growth. It has been shown to play an important role in osteoclast differentiation, particularly at the earlier stages of osteoclastogenesis. mTOR activation and function, as part of mTORC1 complex, is dependent on lysosomal localization and the vacuolar H(+) -ATPase (V-ATPase) activity; however, the precise mechanism is still not well understood. Using primary mouse osteoclasts that are known to have higher lysosomal pH due to R740S mutation in the V-ATPase a3 subunit, we investigated the role of lysosomal pH in mTORC1 signaling. Our results demonstrated that +/R740S cells had increased basal mTOR protein levels and mTORC1 activity compared to +/+ osteoclasts, while mTOR gene expression was decreased. Treatment with lysosomal inhibitors chloroquine and ammonium chloride, compounds known to raise lysosomal pH, significantly increased mTOR protein levels in +/+ cells, confirming the importance of lysosomal pH in mTOR signaling. These results also suggested that mTOR could be degraded in the lysosome. To test this hypothesis, we cultured osteoclasts with chloroquine or proteasomal inhibitor MG132. Both chloroquine and MG132 increased mTOR and p-mTOR protein levels in +/+ osteoclasts, suggesting that mTOR undergoes both lysosomal and proteasomal degradation. Treatment with cycloheximide, an inhibitor of new protein synthesis, confirmed that mTOR is constitutively expressed and degraded. These results show that, in osteoclasts, the lysosome plays a key role not only in mTOR activation but also in its deactivation through protein degradation, representing a novel molecular mechanism of mTOR regulation.

  9. Predicting mTOR Inhibitors with a Classifier Using Recursive Partitioning and Naïve Bayesian Approaches

    PubMed Central

    Wang, Ling; Chen, Lei; Liu, Zhihong; Zheng, Minghao; Gu, Qiong; Xu, Jun

    2014-01-01

    Background Mammalian target of rapamycin (mTOR) is a central controller of cell growth, proliferation, metabolism, and angiogenesis. Thus, there is a great deal of interest in developing clinical drugs based on mTOR. In this paper, in silico models based on multi-scaffolds were developed to predict mTOR inhibitors or non-inhibitors. Methods First 1,264 diverse compounds were collected and categorized as mTOR inhibitors and non-inhibitors. Two methods, recursive partitioning (RP) and naïve Bayesian (NB), were used to build combinatorial classification models of mTOR inhibitors versus non-inhibitors using physicochemical descriptors, fingerprints, and atom center fragments (ACFs). Results A total of 253 models were constructed and the overall predictive accuracies of the best models were more than 90% for both the training set of 964 and the external test set of 300 diverse compounds. The scaffold hopping abilities of the best models were successfully evaluated through predicting 37 new recently published mTOR inhibitors. Compared with the best RP and Bayesian models, the classifier based on ACFs and Bayesian shows comparable or slightly better in performance and scaffold hopping abilities. A web server was developed based on the ACFs and Bayesian method (http://rcdd.sysu.edu.cn/mtor/). This web server can be used to predict whether a compound is an mTOR inhibitor or non-inhibitor online. Conclusion In silico models were constructed to predict mTOR inhibitors using recursive partitioning and naïve Bayesian methods, and a web server (mTOR Predictor) was also developed based on the best model results. Compound prediction or virtual screening can be carried out through our web server. Moreover, the favorable and unfavorable fragments for mTOR inhibitors obtained from Bayesian classifiers will be helpful for lead optimization or the design of new mTOR inhibitors. PMID:24819222

  10. The role of phospholipase D and phosphatidic acid in the mechanical activation of mTOR signaling in skeletal muscle.

    PubMed

    Hornberger, T A; Chu, W K; Mak, Y W; Hsiung, J W; Huang, S A; Chien, S

    2006-03-21

    Signaling by the mammalian target of rapamycin (mTOR) has been reported to be necessary for mechanical load-induced growth of skeletal muscle. The mechanisms involved in the mechanical activation of mTOR signaling are not known, but several studies indicate that a unique [phosphotidylinositol-3-kinase (PI3K)- and nutrient-independent] mechanism is involved. In this study, we have demonstrated that a regulatory pathway for mTOR signaling that involves phospholipase D (PLD) and the lipid second messenger phosphatidic acid (PA) plays a critical role in the mechanical activation of mTOR signaling. First, an elevation in PA concentration was sufficient for the activation of mTOR signaling. Second, the isozymes of PLD (PLD1 and PLD2) are localized to the z-band in skeletal muscle (a critical site of mechanical force transmission). Third, mechanical stimulation of skeletal muscle with intermittent passive stretch ex vivo induced PLD activation, PA accumulation, and mTOR signaling. Finally, pharmacological inhibition of PLD blocked the mechanically induced increase in PA and the activation of mTOR signaling. Combined, these results indicate that mechanical stimuli activate mTOR signaling through a PLD-dependent increase in PA. Furthermore, we showed that mTOR signaling was partially resistant to rapamycin in muscles subjected to mechanical stimulation. Because rapamycin and PA compete for binding to the FRB domain on mTOR, these results suggest that mechanical stimuli activate mTOR signaling through an enhanced binding of PA to the FRB domain on mTOR. PMID:16537399

  11. The role of phospholipase D and phosphatidic acid in the mechanical activation of mTOR signaling in skeletal muscle.

    PubMed

    Hornberger, T A; Chu, W K; Mak, Y W; Hsiung, J W; Huang, S A; Chien, S

    2006-03-21

    Signaling by the mammalian target of rapamycin (mTOR) has been reported to be necessary for mechanical load-induced growth of skeletal muscle. The mechanisms involved in the mechanical activation of mTOR signaling are not known, but several studies indicate that a unique [phosphotidylinositol-3-kinase (PI3K)- and nutrient-independent] mechanism is involved. In this study, we have demonstrated that a regulatory pathway for mTOR signaling that involves phospholipase D (PLD) and the lipid second messenger phosphatidic acid (PA) plays a critical role in the mechanical activation of mTOR signaling. First, an elevation in PA concentration was sufficient for the activation of mTOR signaling. Second, the isozymes of PLD (PLD1 and PLD2) are localized to the z-band in skeletal muscle (a critical site of mechanical force transmission). Third, mechanical stimulation of skeletal muscle with intermittent passive stretch ex vivo induced PLD activation, PA accumulation, and mTOR signaling. Finally, pharmacological inhibition of PLD blocked the mechanically induced increase in PA and the activation of mTOR signaling. Combined, these results indicate that mechanical stimuli activate mTOR signaling through a PLD-dependent increase in PA. Furthermore, we showed that mTOR signaling was partially resistant to rapamycin in muscles subjected to mechanical stimulation. Because rapamycin and PA compete for binding to the FRB domain on mTOR, these results suggest that mechanical stimuli activate mTOR signaling through an enhanced binding of PA to the FRB domain on mTOR.

  12. Combined treatment with everolimus and fulvestrant reversed anti-HER2 resistance in a patient with refractory advanced breast cancer: a case report

    PubMed Central

    Sun, Bing; Ding, Lijuan; Wu, Shikai; Meng, Xiangying; Song, Santai

    2016-01-01

    Background Everolimus, an inhibitor of the mammalian target of rapamycin, shows promising antitumor activity when combined with trastuzumab and chemotherapy for human epidermal growth factor receptor-2 (HER2)-positive breast cancer or when combined with endocrine agents for hormone receptor (HR)-positive tumors. However, data are limited regarding the effect of everolimus in combination with endocrine drugs in HER2-positive advanced breast cancer regardless of the HR status. Case presentation A 44-year-old female was diagnosed with recurrent HER2-positive breast cancer. The primary tumor was HR positive; however, the metastatic tumor was HR negative. The patient was resistant to classical chemotherapeutic agents and anti-HER2 treatment. Thus, the combination of everolimus and fulvestrant, a selective estrogen receptor downregulator, was chosen to reverse the resistance to anti-HER2 therapy. Indeed, the patient experienced long-term disease stabilization. Adverse events associated with the treatment were manageable by dose adjustments. We performed genetic testing of the metastatic tumor, which harbored a PIK3CA gene mutation but was positive for phosphatase and tensin homologue expression, which might result in resistance to the mammalian target of rapamycin inhibitor. Conclusion This case study indicates that combined treatment with everolimus and fulvestrant might be a viable option for the treatment of metastatic breast cancer patients who are HER2 positive and carry a PIK3CA gene mutation but are resistant to anti-HER2 therapy and classical chemotherapeutic agents. Further prospective randomized trials are needed to confirm this finding. PMID:27445490

  13. CZ415, a Highly Selective mTOR Inhibitor Showing in Vivo Efficacy in a Collagen Induced Arthritis Model.

    PubMed

    Cansfield, Andrew D; Ladduwahetty, Tammy; Sunose, Mihiro; Ellard, Katie; Lynch, Rosemary; Newton, Anthea L; Lewis, Ann; Bennett, Gavin; Zinn, Nico; Thomson, Douglas W; Rüger, Anne J; Feutrill, John T; Rausch, Oliver; Watt, Alan P; Bergamini, Giovanna

    2016-08-11

    CZ415, a potent ATP-competitive mTOR inhibitor with unprecedented selectivity over any other kinase is described. In addition to a comprehensive characterization of its activities in vitro, in vitro ADME, and in vivo pharmacokinetic data are reported. The suitability of this inhibitor for studying in vivo mTOR biology is demonstrated in a mechanistic mouse model monitoring mTOR proximal downstream phosphorylation signaling. Furthermore, the compound reported here is the first ATP-competitive mTOR inhibitor described to show efficacy in a semitherapeutic collagen induced arthritis (CIA) mouse model. PMID:27563401

  14. mTOR as a Molecular Target in HPV-Associated Oral and Cervical Squamous Carcinomas

    PubMed Central

    Molinolo, Alfredo A.; Marsh, Christina; Dinali, Mohamed El; Gangane, Nitin; Jennison, Kaitlin; Hewitt, Stephen; Patel, Vyomesh; Seiwert, Tanguy Y.; Gutkind, J. Silvio

    2012-01-01

    Purpose The incidence of head and neck squamous cell carcinomas (HNSCC) associated with papillomavirus (HPV) infection has increased over the past decades in the US. We aimed at examining the global impact of HPV-associated HNSCC, and whether the established key role of mTOR activation in HNSCC is also observed in HPV+ HNSCC lesions, thereby providing novel treatment options for HPV-associated HNSCC patients. Experimental Design An international HNSCC tissue microarray (TMA) was used to analyze the expression of p16INK4A, a surrogate for HPV infection, and Akt-mTOR pathway activation. Results were confirmed in a large collection of HPV− and HPV+ HNSCC cases and in a cervical cancer (CCSCC) TMA. Observations were validated in HNSCC and CCSCC-derived cell lines, which were xenografted into immunodeficient mice for tumorigenesis assays. Results Approximately 20% of all HNSCC lesions could be classified as HPV+, irrespective of their country of origin. mTOR pathway activation was observed in most HPV+ HNSCC and CCSCC lesions and cell lines. The pre-clinical efficacy of mTOR inhibition by rapamycin and RAD001 was explored in HPV+ HNSCC and CCSCC tumor xenografts. Both mTOR inhibitors effectively decreased mTOR activity in vivo, and caused a remarkable decrease in tumor burden. These results emphasize the emerging global impact of HPV-related HNSCCs, and indicate that the activation of the mTOR pathway is a widespread event in both HPV− and HPV-associated HNSCC and CCSCC lesions. Conclusions The emerging results may provide a rationale for the clinical evaluation of mTOR inhibitors as a molecular targeted approach for the treatment of HPV-associated malignancies. PMID:22409888

  15. Use of a small particle solid-core packing for improved efficiency and rapid measurement of sirolimus and everolimus by LC-MS/MS.

    PubMed

    Morgan, Phillip; Nwafor, Magnus; Tredger, Mike

    2016-06-01

    Measurement of whole blood sirolimus and everolimus is required in order to optimize patient treatment following solid organ transplant. Assay by LC-MS/MS is increasingly preferred; however efficient use of the instrument and short turnaround times are crucial. Use of a 1.6 µm solid-core packing HPLC column (Cortecs) gave significant increases in efficiency, sensitivity and throughput compared with an existing method, following simple protein precipitation of small-volume (20 μL) whole blood samples. Sirolimus, everolimus and the stable isotopic internal standard ((13) C2 D4 - everolimus) eluted at around 0.8 min, and total analytical run time was 2.2 min, saving almost 4 min per sample compared with an existing method. Within-assay imprecision (CV) was 3.3-8.5%, and between-assay imprecision was 2.2-10.8%. Retrospective assay of external quality assurance samples and comparison of patient samples assayed in parallel showed only small differences (between +6.8 and -1.9%) in results using the Cortecs column when compared with the existing method. No significant interferences or ion suppression were observed. Copyright © 2015 John Wiley & Sons, Ltd.

  16. Tacrolimus plus mycophenolate mofetil vs. cyclosporine plus everolimus in deceased donor kidney transplant recipients: three-yr results of a single-center prospective clinical trial.

    PubMed

    Favi, Evaldo; Spagnoletti, Gionata; Salerno, Maria P; Pedroso, José A; Romagnoli, Jacopo; Citterio, Franco

    2013-01-01

    We compared in kidney transplantation two immunosuppressive regimens: tacrolimus plus mycophenolate mofetil (MMF) (TAC) and everolimus plus low-dose cyclosporine (EVE). Sixty consecutive patients received TAC (30 patients) or EVE (30 patients) as immunosuppressive regimen; all subjects also received induction with basiliximab and corticosteroids. After three-yr follow-up, no difference was found in patient and graft survival (PTS: TAC: 97% vs. EVE: 100%; GS: TAC: 93% vs. EVE: 93%). The incidence of acute rejection was higher in the EVE group but the difference was not statistically significant (17% vs. 23%, p = ns). Patients in EVE showed higher serum cholesterol (205 ± 41 vs. 235 ± 41 mg/dL, p = 0.0012) and lower hemoglobin concentration (13.6 ± 1.4 vs. 12.4 ± 1.9, p = 0.01). Renal function was not significantly different in the two groups (3 Y creatinine: TAC 1.4 ± 0.8 vs. EVE 1.6 ± 0.8 mg/dL, p = ns). Treatment discontinuation was higher in the EVE group (TAC 17 vs. EVE 36%, p = ns). Our data show that in the middle-term follow-up, an immunosuppressive regimen with tacrolimus plus MMF has a similar efficacy and safety profile in comparison with the combination of low-exposure cyclosporine plus everolimus. Further follow up could evidence the benefits related to the anti-proliferative effects of everolimus.

  17. mTOR Overactivation and Compromised Autophagy in the Pathogenesis of Pulmonary Fibrosis

    PubMed Central

    Gui, Yao-Song; Wang, Lianmei; Tian, Xinlun; Li, Xue; Ma, Aiping; Zhou, Weixun; Zeng, Ni; Zhang, Ji; Cai, Baiqiang; Zhang, Hongbing; Chen, Jing-Yu; Xu, Kai-Feng

    2015-01-01

    The mammalian target of rapamycin (mTOR) signaling pathway in pulmonary fibrosis was investigated in cell and animal models. mTOR overactivation in alveolar epithelial cells (AECs) was achieved in the conditional and inducible Tsc1 knock-down mice SPC-rtTA/TetO-Cre/Tsc1fx/+ (STT). Doxycycline caused Tsc1 knock-down and consequently mTOR activation in AECs for the STT mice. Mice treated with bleomycin exhibited increased mortality and pulmonary fibrosis compared with control mice. In wild-type C57BL/6J mice, pretreatment with rapamycin attenuated the bleomycin-mediated mortality and fibrosis. Rapamycin-mediated mouse survival benefit was inhibited by chloroquine, an autophagy inhibitor. Autophagosomes were decreased in the lungs after bleomycin exposure. Rapamycin induced the production of autophagosomes and diminished p62. We concluded that mTOR overactivation in AECs and compromised autophagy in the lungs are involved in the pathogenesis of pulmonary fibrosis. The suppression of mTOR and enhancement of autophagy may be used for treatment of pulmonary fibrosis. PMID:26382847

  18. mTOR: Driving apoptosis and autophagy for neurocardiac complications of diabetes mellitus

    PubMed Central

    Maiese, Kenneth

    2015-01-01

    The World Health Organization estimates that diabetes mellitus (DM) will become the seventh leading cause of death during the next two decades. DM affects approximately 350 million individuals worldwide and additional millions that remain undiagnosed are estimated to suffer from the complications of DM. Although the complications of DM can be seen throughout the body, the nervous, cardiac, and vascular systems can be significantly affected and lead to disorders that include cognitive loss, stroke, atherosclerosis, cardiac failure, and endothelial stem cell impairment. At the cellular level, oxidative stress is a significant determinant of cell fate during DM and leads to endoplasmic reticulum stress, mitochondrial dysfunction, apoptosis, and autophagy. Multiple strategies are being developed to combat the complications of DM, but it is the mechanistic target of rapamycin (mTOR) that is gaining interest in drug development circles especially for protective therapies that involve cytokines and growth factors such as erythropoietin. The pathways of mTOR linked to mTOR complex 1, mTOR complex 2, AMP activated protein kinase, and the hamartin (tuberous sclerosis 1)/tuberin (tuberous sclerosis 2) complex can ultimately influence neuronal, cardiac, and vascular cell survival during oxidant stress in DM through a fine interplay between apoptosis and autophagy. Further understanding of these mTOR regulated pathways should foster novel strategies for the complications of DM that impact millions of individuals with death and disability. PMID:25789103

  19. Temporal mTOR inhibition protects Fbxw7-deficient mice from radiation-induced tumor development

    PubMed Central

    Liu, Yueyong; Huang, Yurong; Wang, Zeran; Huang, Yong; Li, Xiaohua; Louie, Alexander; Wei, Guangwei; Mao, Jian-Hua

    2013-01-01

    FBXW7 acts as a tumor suppressor in numerous types of human cancers through ubiquitination of different oncoproteins including mTOR. However, how the mutation/loss of Fbxw7 results in tumor development remains largely unknown. Here we report that downregulation of mTOR by radiation is Fbxw7-dependent, and short-term mTOR inhibition by rapamycin after exposure to radiation significantly postpones tumor development in Fbxw7/p53 double heterozygous (Fbxw7+/−p53+/−) mice but not in p53 single heterozygous (p53+/−) mice. Tumor latency of rapamycin treated Fbxw7+/−p53+/− mice is remarkably similar to those of p53+/− mice while placebo treated Fbxw7+/−p53+/− mice develop tumor significantly earlier than placebo treated p53+/− mice. Furthermore, we surprisingly find that, although temporal treatment of rapamycin is given at a young age, the inhibition of mTOR activity sustainably remains in tumors. These results indicate that inhibition of mTOR signaling pathway suppresses the contribution of Fbxw7 loss toward tumor development. PMID:23454868

  20. Distinct amino acid-sensing mTOR pathways regulate skeletal myogenesis.

    PubMed

    Yoon, Mee-Sup; Chen, Jie

    2013-12-01

    Signaling through the mammalian target of rapamycin (mTOR) in response to amino acid availability controls many cellular and developmental processes. mTOR is a master regulator of myogenic differentiation, but the pathways mediating amino acid signals in this process are not known. Here we examine the Rag GTPases and the class III phosphoinositide 3-kinase (PI3K) Vps34, two mediators of amino acid signals upstream of mTOR complex 1 (mTORC1) in cell growth regulation, for their potential involvement in myogenesis. We find that, although both Rag and Vps34 mediate amino acid activation of mTORC1 in C2C12 myoblasts, they have opposing functions in myogenic differentiation. Knockdown of RagA/B enhances, whereas overexpression of active RagB/C mutants impairs, differentiation, and this inhibitory function of Rag is mediated by mTORC1 suppression of the IRS1-PI3K-Akt pathway. On the other hand, Vps34 is required for myogenic differentiation. Amino acids activate a Vps34-phospholipase D1 (PLD1) pathway that controls the production of insulin-like growth factor II, an autocrine inducer of differentiation, through the Igf2 muscle enhancer. The product of PLD, phosphatidic acid, activates the enhancer in a rapamycin-sensitive but mTOR kinase-independent manner. Our results uncover amino acid-sensing mechanisms controlling the homeostasis of myogenesis and underline the versatility and context dependence of mTOR signaling.

  1. Clinical Impact of Dual Antiplatelet Therapy Use in Patients Following Everolimus-eluting Stent Implantation: Insights from the SEEDS Study

    PubMed Central

    Zhang, Yao-Jun; Zhao, Ye-Lin; Xu, Bo; Han, Ya-Ling; Li, Bao; Liu, Qiang; Su, Xi; Pang, Si; Lu, Shu-Zheng; Guo, Xiao-Feng; Yang, Yue-Jin

    2015-01-01

    Background: Studies have suggested that use of prolonged dual antiplatelet therapy (DAPT) following new generation drug-eluting stent implantation may increase costs and potential bleeding events. This study aimed to investigate the association of DAPT status with clinical safety in patients undergoing everolimus-eluting stent (EES) implantation in the SEEDS study (A Registry to Evaluate Safety and Effectiveness of Everolimus Drug-eluting Stent for Coronary Revascularization) at 2-year follow-up. Methods: The SEEDS study is a prospective, multicenter study, where patients (n = 1900) with small vessel, long lesion, or multi-vessel diseases underwent EES implantation. Detailed DAPT status was collected at baseline, 6-month, 1- and 2-year. DAPT interruption was defined as any interruption of aspirin and/or clopidogrel more than 14 days. The net adverse clinical events (NACE, a composite endpoint of all-cause death, all myocardial infarction (MI), stroke, definite/probable stent thrombosis (ST), and major bleeding (Bleeding Academic Research Consortium II-V)) were investigated according to the DAPT status at 2-year follow-up. Results: DAPT was used in 97.8% of patients at 6 months, 69.5% at 12 months and 35.4% at 2 years. It was observed that the incidence of NACE was low (8.1%) at 2 years follow-up, especially its components of all-cause death (0.9%), stroke (1.1%), and definite/probable ST (0.7%). DAPT was not an independent predictor of composite endpoint of all-cause death/MI/stroke (hazard ratio [HR]: 0.693, 95% confidence interval [CI]: 0.096–4.980, P = 0.715) and NACE (HR: 1.041, 95% CI: 0.145–7.454, P = 0.968). Of 73 patients who had DAPT interruption, no patient had ST at 12-month, and only 1 patient experienced ST between 1- and 2-year (1.4%). There was a high frequency of major bleeding events (53/65, 82.5%) occurred in patients receiving DAPT treatment. Conclusions: Prolonged DAPT use was not associated with improved clinical safety. The study

  2. Che-1-induced inhibition of mTOR pathway enables stress-induced autophagy

    PubMed Central

    Desantis, Agata; Bruno, Tiziana; Catena, Valeria; De Nicola, Francesca; Goeman, Frauke; Iezzi, Simona; Sorino, Cristina; Ponzoni, Maurilio; Bossi, Gianluca; Federico, Vincenzo; La Rosa, Francesca; Ricciardi, Maria Rosaria; Lesma, Elena; De Meo, Paolo D'Onorio; Castrignanò, Tiziana; Petrucci, Maria Teresa; Pisani, Francesco; Chesi, Marta; Bergsagel, P Leif; Floridi, Aristide; Tonon, Giovanni; Passananti, Claudio; Blandino, Giovanni; Fanciulli, Maurizio

    2015-01-01

    Mammalian target of rapamycin (mTOR) is a key protein kinase that regulates cell growth, metabolism, and autophagy to maintain cellular homeostasis. Its activity is inhibited by adverse conditions, including nutrient limitation, hypoxia, and DNA damage. In this study, we demonstrate that Che-1, a RNA polymerase II-binding protein activated by the DNA damage response, inhibits mTOR activity in response to stress conditions. We found that, under stress, Che-1 induces the expression of two important mTOR inhibitors, Redd1 and Deptor, and that this activity is required for sustaining stress-induced autophagy. Strikingly, Che-1 expression correlates with the progression of multiple myeloma and is required for cell growth and survival, a malignancy characterized by high autophagy response. PMID:25770584

  3. Inhibition of the mechanistic target of rapamycin (mTOR) - Rapamycin and beyond

    PubMed Central

    Lamming, Dudley W.

    2016-01-01

    Rapamycin is an FDA-approved immunosuppressant and anti-cancer agent discovered in the soil of Easter Island in the early 1970s. Rapamycin is a potent and selective inhibitor of the mTOR (mechanistic Target Of Rapamycin) protein kinase, which acts as a central integrator of nutrient signaling pathways. During the last decade, genetic and pharmaceutical inhibition of mTOR pathway signaling has been found to promote longevity in yeast, worms, flies and mice. In this chapter, we will discuss the molecular biology underlying the effects of rapamycin and its physiological effects; evidence for rapamycin as an anti-aging compound; mechanisms by which rapamycin may extend lifespan; and the potential limitations of rapamycin as an anti-aging molecule. Finally, we will discuss possible strategies that may allow us to inhibit mTOR signaling safely while minimizing side effects, and reap the health, social and economic benefits from slowing the aging process. PMID:27048303

  4. mTOR Links Environmental Signals to T Cell Fate Decisions

    PubMed Central

    Chapman, Nicole M.; Chi, Hongbo

    2015-01-01

    T cell fate decisions play an integral role in maintaining the health of organisms under homeostatic and inflammatory conditions. The localized microenvironment in which developing and mature T cells reside provides signals that serve essential functions in shaping these fate decisions. These signals are derived from the immune compartment, including antigens, co-stimulation, and cytokines, and other factors, including growth factors and nutrients. The mechanistic target of rapamycin (mTOR), a vital sensor of signals within the immune microenvironment, is a central regulator of T cell biology. In this review, we discuss how various environmental cues tune mTOR activity in T cells, and summarize how mTOR integrates these signals to influence multiple aspects of T cell biology. PMID:25653651

  5. MicroRNA-96 promotes myocardial hypertrophy by targeting mTOR

    PubMed Central

    Sun, Xuemei; Zhang, Chunlai

    2015-01-01

    As a main cause of cardiac hypertrophy, myocardial hypertrophy includes the proliferation and enlongation of myocardial cell, resulting in abnormally cardiac enlargement. However, the pathogenesis and the molecular mechanism that regulate gene expression of myocardial hypertrophy remain incompletely understood. MiRNAs were deemed as an important molecules involved in a variety of pathological processes. MiR-96 has been reported being associated with the tumor proliferation, but whether miR-96 is involved in cardiac hypertrophy remains uncertain. In this study, we have confirmed that, as the myocardial hypertrophy gene, mTOR was a target gene of miR-96, who would promote the occurrence of myocardial hypertrophy. Thus, we got the conclusion that miR-96 could promote myocardial hypertrophy by inhibiting mTOR, miR-96 and mTOR were negatively correlated. PMID:26823769

  6. Age related increase in mTOR activity contributes to the pathological changes in ovarian surface epithelium

    PubMed Central

    Bajwa, Preety; Nagendra, Prathima B.; Nielsen, Sarah; Sahoo, Subhransu S.; Bielanowicz, Amanda; Lombard, Janine M.; Wilkinson, Erby J.; Miller, Richard A.; Tanwar, Pradeep S.

    2016-01-01

    Ovarian cancer is a disease of older women. However, the molecular mechanisms of ovarian aging and their contribution to the pathogenesis of ovarian cancer are currently unclear. mTOR signalling is a major regulator of aging as suppression of this pathway extends lifespan in model organisms. Overactive mTOR signalling is present in up to 80% of ovarian cancer samples and is associated with poor prognosis. This study examined the role of mTOR signalling in age-associated changes in ovarian surface epithelium (OSE). Histological examination of ovaries from both aged mice and women revealed OSE cell hyperplasia, papillary growth and inclusion cysts. These pathological lesions expressed bonafide markers of ovarian cancer precursor lesions, Pax8 and Stathmin 1, and were presented with elevated mTOR signalling. To understand whether overactive mTOR signalling is responsible for the development of these pathological changes, we analysed ovaries of the Pten trangenic mice and found significant reduction in OSE lesions compared to controls. Furthermore, pharmacological suppression of mTOR signalling significantly decreased OSE hyperplasia in aged mice. Treatment with mTOR inhibitors reduced human ovarian cancer cell viability, proliferation and colony forming ability. Collectively, we have established the role of mTOR signalling in age-related OSE pathologies and initiation of ovarian cancer. PMID:27036037

  7. Age related increase in mTOR activity contributes to the pathological changes in ovarian surface epithelium.

    PubMed

    Bajwa, Preety; Nagendra, Prathima B; Nielsen, Sarah; Sahoo, Subhransu S; Bielanowicz, Amanda; Lombard, Janine M; Wilkinson, J Erby; Miller, Richard A; Tanwar, Pradeep S

    2016-04-12

    Ovarian cancer is a disease of older women. However, the molecular mechanisms of ovarian aging and their contribution to the pathogenesis of ovarian cancer are currently unclear. mTOR signalling is a major regulator of aging as suppression of this pathway extends lifespan in model organisms. Overactive mTOR signalling is present in up to 80% of ovarian cancer samples and is associated with poor prognosis. This study examined the role of mTOR signalling in age-associated changes in ovarian surface epithelium (OSE). Histological examination of ovaries from both aged mice and women revealed OSE cell hyperplasia, papillary growth and inclusion cysts. These pathological lesions expressed bonafide markers of ovarian cancer precursor lesions, Pax8 and Stathmin 1, and were presented with elevated mTOR signalling. To understand whether overactive mTOR signalling is responsible for the development of these pathological changes, we analysed ovaries of the Pten trangenic mice and found significant reduction in OSE lesions compared to controls. Furthermore, pharmacological suppression of mTOR signalling significantly decreased OSE hyperplasia in aged mice. Treatment with mTOR inhibitors reduced human ovarian cancer cell viability, proliferation and colony forming ability. Collectively, we have established the role of mTOR signalling in age-related OSE pathologies and initiation of ovarian cancer.

  8. Hypothalamic roles of mTOR complex I: Integration of nutrient and hormone signals to regulate energy homeostasis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mammalian or mechanistic target of rapamycin (mTOR) senses nutrient, energy, and hormone signals to regulate metabolism and energy homeostasis. mTOR activity in the hypothalamus, which is associated with changes in energy status, plays a critical role in the regulation of food intake and body weight...

  9. Comparative idiosyncrasies in life extension by reduced mTOR signalling and its distinctiveness from dietary restriction.

    PubMed

    Garratt, Michael; Nakagawa, Shinichi; Simons, Mirre J P

    2016-08-01

    Reduced mechanistic target of rapamycin (mTOR) signalling extends lifespan in yeast, nematodes, fruit flies and mice, highlighting a physiological pathway that could modulate aging in evolutionarily divergent organisms. This signalling system is also hypothesized to play a central role in lifespan extension via dietary restriction. By collating data from 48 available published studies examining lifespan with reduced mTOR signalling, we show that reduced mTOR signalling provides similar increases in median lifespan across species, with genetic mTOR manipulations consistently providing greater life extension than pharmacological treatment with rapamycin. In contrast to the consistency in changes in median lifespan, however, the demographic causes for life extension are highly species specific. Reduced mTOR signalling extends lifespan in nematodes by strongly reducing the degree to which mortality rates increase with age (aging rate). By contrast, life extension in mice and yeast occurs largely by pushing back the onset of aging, but not altering the shape of the mortality curve once aging starts. Importantly, in mice, the altered pattern of mortality induced by reduced mTOR signalling is different to that induced by dietary restriction, which reduces the rate of aging. Effects of mTOR signalling were also sex dependent, but only within mice, and not within flies, thus again species specific. An alleviation of age-associated mortality is not a shared feature of reduced mTOR signalling across model organisms and does not replicate the established age-related survival benefits of dietary restriction. PMID:27139919

  10. B cell-specific deficiencies in mTOR limit humoral immune responses.

    PubMed

    Zhang, Shuling; Pruitt, Margaret; Tran, Dena; Du Bois, Wendy; Zhang, Ke; Patel, Rushi; Hoover, Shelley; Simpson, R Mark; Simmons, John; Gary, Joy; Snapper, Clifford M; Casellas, Rafael; Mock, Beverly A

    2013-08-15

    Generation of high-affinity Abs in response to Ags/infectious agents is essential for developing long-lasting immune responses. B cell maturation and Ab responses to Ag stimulation require Ig somatic hypermutation (SHM) and class-switch recombination (CSR) for high-affinity responses. Upon immunization with either the model Ag 4-hydroxy-3-nitrophenylacetyl hapten (NP) conjugated to chicken γ globulin lysine (NP-CGG) or heat-killed Streptococcus pneumoniae capsular type 14 protein (Pn14), knock-in (KI) mice hypomorphic for mTOR function had a decreased ability to form germinal centers, develop high-affinity anti-NP-specific or anti-Pn14-specific Abs, and perform SHM/CSR. Hypomorphic mTOR mice also had a high mortality (40%) compared with wild-type (WT) (0%) littermates and had lower pneumococcal surface protein A-specific Ab titers when immunized and challenged with live S. pneumoniae infection. Mice with mTOR deleted in their B cell lineage (knockout [KO]) also produced fewer splenic germinal centers and decreased high-affinity Ab responses to NP-CGG than did their WT littermates. CSR rates were lower in mTOR KI and KO mice, and pharmacologic inhibition of mTOR in WT B cells resulted in decreased rates of ex vivo CSR. RNA and protein levels of activation-induced cytidine deaminase (AID), a protein essential for SHM and CSR, were lower in B cells from both KI and B cell-specific KO mice, concomitant with increases in phosphorylated AKT and FOXO1. Rescue experiments increasing AID expression in KI B cells restored CSR levels to those in WT B cells. Thus, mTOR plays an important immunoregulatory role in the germinal center, at least partially through AID signaling, in generating high-affinity Abs.

  11. mTOR inhibition as an adjuvant therapy in a metastatic model of HPV+ HNSCC

    PubMed Central

    Coppock, Joseph D.; Vermeer, Paola D.; Vermeer, Daniel W.; Lee, Kimberly M.; Miskimins, W. Keith; Spanos, William C.; Lee, John H.

    2016-01-01

    Effective treatments for recurrent/metastatic human papillomavirus-positive (HPV+) head and neck squamous cell cancer (HNSCC) are limited. To aid treatment development, we characterized a novel murine model of recurrent/metastatic HPV+ HNSCC. Further analysis of the parental tumor cell line and its four recurrent/metastatic derivatives led to preclinical testing of an effective treatment option for this otherwise fatal disease. Reverse phase protein arrays identified key signaling cascades in the parental and recurrent/metastatic cell lines. While protein expression profiles differed among the recurrent/metastatic cell lines, activated proteins associated with the mTOR signaling cascade were a commonality. Based on these data, mTOR inhibition was evaluated as an adjuvant treatment for recurrent/metastatic disease. mTOR activity and treatment response were assessed in vitro by western blot, Seahorse, proliferation, clonogenic, and migration assays. Standard-of-care cisplatin/radiation therapy (CRT) versus CRT/rapamycin were compared in vivo. Low-dose rapamycin inhibited mTOR signaling, decreasing proliferation (43%) and migration (62%) while it enhanced CRT-induced cytotoxicity (3.3 fold) in clonogenic assays. Furthermore, rapamycin re-sensitized CRT-resistant, metastatic tumors to treatment in vivo, improving long-term cures (0–30% improved to 78–100%, depending on the recurrent/metastatic cell line) and limiting lymph node metastasis (32%) and lung metastatic burden (30 fold). Studies using immune compromised mice suggested rapamycin's effect on metastasis is independent of the adaptive immune response. These data suggest a role of mTOR activation in HPV+ HNSCC recurrent/metastatic disease and that adjuvant mTOR inhibition may enhance treatment of resistant, metastatic cell populations at the primary site and limit distant metastasis. PMID:27015118

  12. Phosphatidic acid enhances mTOR signaling and resistance exercise induced hypertrophy

    PubMed Central

    2014-01-01

    Introduction The lipid messenger phosphatidic acid (PA) plays a critical role in the stimulation of mTOR signaling. However, the mechanism by which PA stimulates mTOR is currently unknown. Therefore, the purpose of this study was to compare the effects of various PA precursors and phospholipids on their ability to stimulate mTOR signaling and its ability to augment resistance training-induced changes in body composition and performance. Methods In phase one, C2C12 myoblasts cells were stimulated with different phospholipids and phospholipid precursors derived from soy and egg sources. The ratio of phosphorylated p70 (P-p70-389) to total p70 was then used as readout for mTOR signaling. In phase two, resistance trained subjects (n = 28, 21 ± 3 years, 77 ± 4 kg, 176 ± 9 cm) consumed either 750 mg PA daily or placebo and each took part in an 8 week periodized resistance training program. Results In phase one, soy-phosphatidylserine, soy-Lyso-PA, egg-PA, and soy-PA stimulated mTOR signaling, and the effects of soy-PA (+636%) were significantly greater than egg-PA (+221%). In phase two, PA significantly increased lean body mass (+2.4 kg), cross sectional area (+1.0 cm), and leg press strength (+51.9 kg) over placebo. Conclusion PA significantly activates mTOR and significantly improved responses in skeletal muscle hypertrophy, lean body mass, and maximal strength to resistance exercise. PMID:24959196

  13. Gβγ interacts with mTOR and promotes its activation

    SciTech Connect

    Robles-Molina, Evelyn; Dionisio-Vicuña, Misael; Guzmán-Hernández, María Luisa; Reyes-Cruz, Guadalupe; Vázquez-Prado, José

    2014-02-07

    Highlights: • Gβγ interacts with mTOR kinase domain via a mechanism sensitive to chronic treatment with rapamycin. • Gβγ interacts with mTORC1 and mTORC2 which correlates with its ability to promote mTORC1 and mTORC2 signaling. • Gβγ heterodimers containing different Gβ subunits, except Gβ{sub 4}, interact with mTOR. - Abstract: Diverse G protein-coupled receptors depend on Gβγ heterodimers to promote cell polarization and survival via direct activation of PI3Kγ and potentially other effectors. These events involve full activation of AKT via its phosphorylation at Ser473, suggesting that mTORC2, the kinase that phosphorylates AKT at Ser473, is activated downstream of Gβγ. Thus, we tested the hypothesis that Gβγ directly contributes to mTOR signaling. Here, we demonstrate that endogenous mTOR interacts with Gβγ. Cell stimulation with serum modulates Gβγ interaction with mTOR. The carboxyl terminal region of mTOR, expressed as a GST-fusion protein, including the serine/threonine kinase domain, binds Gβγ heterodimers containing different Gβ subunits, except Gβ{sub 4}. Both, mTORC1 and mTORC2 complexes interact with Gβ{sub 1}γ{sub 2} which promotes phosphorylation of their respective substrates, p70S6K and AKT. In addition, chronic treatment with rapamycin, a condition known to interfere with assembly of mTORC2, reduces the interaction between Gβγ and mTOR and the phosphorylation of AKT; whereas overexpression of Gαi interfered with the effect of Gβγ as promoter of p70S6K and AKT phosphorylation. Altogether, our results suggest that Gβγ positively regulates mTOR signaling via direct interactions and provide further support to emerging strategies based on the therapeutical potential of inhibiting different Gβγ signaling interfaces.

  14. Discovery and optimization of potent and selective benzonaphthyridinone analogs as small molecule mTOR inhibitors with improved mouse microsome stability

    PubMed Central

    Liu, Qingsong; Wang, Jinhua; Kang, Seong A.; Thoreen, Carson C.; Hur, Wooyoung; Choi, Hwan Geun; Waller, David L.; Sim, Taebo; Sabatini, David M.; Gray, Nathanael S.

    2014-01-01

    Starting from small molecule mTOR inhibitor Torin1, replacement of the piperazine ring with a phenyl ring resulted in a new series of mTOR inhibitors (as exemplified by 10) that showed superior potency and selectivity for mTOR, along with significantly improved mouse liver microsome stability and a longer in vivo half-life. PMID:21621413

  15. mTOR ensures increased release and reduced uptake of the organic osmolyte taurine under hypoosmotic conditions in mouse fibroblasts.

    PubMed

    Lambert, Ian Henry; Jensen, Jane Vendelbo; Pedersen, Per Amstrup

    2014-06-01

    Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that modulates translation in response to growth factors and alterations in nutrient availability following hypoxia and DNA damage. Here we demonstrate that mTOR activity in Ehrlich Lettré ascites (ELA) cells is transiently increased within minutes following osmotic cell swelling and that inhibition of phosphatidylinositol-3-phosphatase (PTEN) counteracts the upstream phosphatidylinositol kinase and potentiates mTOR activity. PTEN inhibition concomitantly potentiates swelling-induced taurine release via the volume-sensitive transporter for organic osmolytes and anion channels (VSOAC) and enhances swelling-induced inhibition of taurine uptake via the taurine-specific transporter (TauT). Chronic osmotic stress, i.e., exposure to hypotonic or hypertonic media for 24 h, reduces and increases mTOR activity in ELA cells, respectively. Using rapamycin, we demonstrate that mTOR inhibition is accompanied by reduction in TauT activity and increase in VSOAC activity in cells expressing high (NIH3T3 fibroblasts) or low (ELA) amounts of mTOR protein. The effect of mTOR inhibition on TauT activity reflects reduced TauT mRNA, TauT protein abundance, and an overall reduction in protein synthesis, whereas the effect on VSOAC is mimicked by catalase inhibition and correlates with reduced catalase mRNA abundance. Hence, mTOR activity favors loss of taurine following hypoosmotic cell swelling, i.e., release via VSOAC and uptake via TauT during acute hypotonic exposure is potentiated and reduced, respectively, by phosphorylation involving mTOR and/or the kinases upstream to mTOR. Decrease in TauT activity during chronic hypotonic exposure, on the other hand, involves reduction in expression/activity of TauT and enzymes in antioxidative defense. PMID:24696147

  16. CC-223, a Potent and Selective Inhibitor of mTOR Kinase: In Vitro and In Vivo Characterization.

    PubMed

    Mortensen, Deborah S; Fultz, Kimberly E; Xu, Shuichan; Xu, Weiming; Packard, Garrick; Khambatta, Godrej; Gamez, James C; Leisten, Jim; Zhao, Jingjing; Apuy, Julius; Ghoreishi, Kamran; Hickman, Matt; Narla, Rama Krishna; Bissonette, Rene; Richardson, Samantha; Peng, Sophie X; Perrin-Ninkovic, Sophie; Tran, Tam; Shi, Tao; Yang, Wen Qing; Tong, Zeen; Cathers, Brian E; Moghaddam, Mehran F; Canan, Stacie S; Worland, Peter; Sankar, Sabita; Raymon, Heather K

    2015-06-01

    mTOR is a serine/threonine kinase that regulates cell growth, metabolism, proliferation, and survival. mTOR complex-1 (mTORC1) and mTOR complex-2 (mTORC2) are critical mediators of the PI3K-AKT pathway, which is frequently mutated in many cancers, leading to hyperactivation of mTOR signaling. Although rapamycin analogues, allosteric inhibitors that target only the mTORC1 complex, have shown some clinical activity, it is hypothesized that mTOR kinase inhibitors, blocking both mTORC1 and mTORC2 signaling, will have expanded therapeutic potential. Here, we describe the preclinical characterization of CC-223. CC-223 is a potent, selective, and orally bioavailable inhibitor of mTOR kinase, demonstrating inhibition of mTORC1 (pS6RP and p4EBP1) and mTORC2 [pAKT(S473)] in cellular systems. Growth inhibitory activity was demonstrated in hematologic and solid tumor cell lines. mTOR kinase inhibition in cells, by CC-223, resulted in more complete inhibition of the mTOR pathway biomarkers and improved antiproliferative activity as compared with rapamycin. Growth inhibitory activity and apoptosis was demonstrated in a panel of hematologic cancer cell lines. Correlative analysis revealed that IRF4 expression level associates with resistance, whereas mTOR pathway activation seems to associate with sensitivity. Treatment with CC-223 afforded in vivo tumor biomarker inhibition in tumor-bearing mice, after a single oral dose. CC-223 exhibited dose-dependent tumor growth inhibition in multiple solid tumor xenografts. Significant inhibition of mTOR pathway markers pS6RP and pAKT in CC-223-treated tumors suggests that the observed antitumor activity of CC-223 was mediated through inhibition of both mTORC1 and mTORC2. CC-223 is currently in phase I clinical trials.

  17. mTOR regulates skeletal muscle regeneration in vivo through kinase-dependent and kinase-independent mechanisms.

    PubMed

    Ge, Yejing; Wu, Ai-Luen; Warnes, Christine; Liu, Jianming; Zhang, Chongben; Kawasome, Hideki; Terada, Naohiro; Boppart, Marni D; Schoenherr, Christopher J; Chen, Jie

    2009-12-01

    Rapamycin-sensitive signaling is required for skeletal muscle differentiation and remodeling. In cultured myoblasts, the mammalian target of rapamycin (mTOR) has been reported to regulate differentiation at different stages through distinct mechanisms, including one that is independent of mTOR kinase activity. However, the kinase-independent function of mTOR remains controversial, and no in vivo studies have examined those mTOR myogenic mechanisms previously identified in vitro. In this study, we find that rapamycin impairs injury-induced muscle regeneration. To validate the role of mTOR with genetic evidence and to probe the mechanism of mTOR function, we have generated and characterized transgenic mice expressing two mutants of mTOR under the control of human skeletal actin (HSA) promoter: rapamycin-resistant (RR) and RR/kinase-inactive (RR/KI). Our results show that muscle regeneration in rapamycin-administered mice is restored by RR-mTOR expression. In the RR/KI-mTOR mice, nascent myofiber formation during the early phase of regeneration proceeds in the presence of rapamycin, but growth of the regenerating myofibers is blocked by rapamycin. Igf2 mRNA levels increase drastically during early regeneration, which is sensitive to rapamycin in wild-type muscles but partially resistant to rapamycin in both RR- and RR/KI-mTOR muscles, consistent with mTOR regulation of Igf2 expression in a kinase-independent manner. Furthermore, systemic ablation of S6K1, a target of mTOR kinase, results in impaired muscle growth but normal nascent myofiber formation during regeneration. Therefore, mTOR regulates muscle regeneration through kinase-independent and kinase-dependent mechanisms at the stages of nascent myofiber formation and myofiber growth, respectively.

  18. mTOR Ser-2481 Autophosphorylation Monitors mTORC-specific Catalytic Activity and Clarifies Rapamycin Mechanism of Action*

    PubMed Central

    Soliman, Ghada A.; Acosta-Jaquez, Hugo A.; Dunlop, Elaine A.; Ekim, Bilgen; Maj, Nicole E.; Tee, Andrew R.; Fingar, Diane C.

    2010-01-01

    The mammalian target of rapamycin (mTOR) Ser/Thr kinase signals in at least two multiprotein complexes distinguished by their different partners and sensitivities to rapamycin. Acute rapamycin inhibits signaling by mTOR complex 1 (mTORC1) but not mTOR complex 2 (mTORC2), which both promote cell growth, proliferation, and survival. Although mTORC2 regulation remains poorly defined, diverse cellular mitogens activate mTORC1 signaling in a manner that requires sufficient levels of amino acids and cellular energy. Before the identification of distinct mTOR complexes, mTOR was reported to autophosphorylate on Ser-2481 in vivo in a rapamycin- and amino acid-insensitive manner. These results suggested that modulation of mTOR intrinsic catalytic activity does not universally underlie mTOR regulation. Here we re-examine the regulation of mTOR Ser-2481 autophosphorylation (Ser(P)-2481) in vivo by studying mTORC-specific Ser(P)-2481 in mTORC1 and mTORC2, with a primary focus on mTORC1. In contrast to previous work, we find that acute rapamycin and amino acid withdrawal markedly attenuate mTORC1-associated mTOR Ser(P)-2481 in cycling cells. Although insulin stimulates both mTORC1- and mTORC2-associated mTOR Ser(P)-2481 in a phosphatidylinositol 3-kinase-dependent manner, rapamycin acutely inhibits insulin-stimulated mTOR Ser(P)-2481 in mTORC1 but not mTORC2. By interrogating diverse mTORC1 regulatory input, we find that without exception mTORC1-activating signals promote, whereas mTORC1-inhibitory signals decrease mTORC1-associated mTOR Ser(P)-2481. These data suggest that mTORC1- and likely mTORC2-associated mTOR Ser-2481 autophosphorylation directly monitors intrinsic mTORC-specific catalytic activity and reveal that rapamycin inhibits mTORC1 signaling in vivo by reducing mTORC1 catalytic activity. PMID:20022946

  19. Allosteric and ATP-competitive kinase inhibitors of mTOR for cancer treatment.

    PubMed

    García-Echeverría, Carlos

    2010-08-01

    Over the past few years a number of components of the PI3K/mTOR pathway have been the subject of intense drug discovery activities both in pharmaceutical companies and in academia. This review article summarizes progress made in the identification and development of allosteric and ATP-competitive kinase inhibitors of mTOR and their potential therapeutic use in oncology.

  20. mTOR and differential activation of mitochondria orchestrate neutrophil chemotaxis.

    PubMed

    Bao, Yi; Ledderose, Carola; Graf, Amelie F; Brix, Bianca; Birsak, Theresa; Lee, Albert; Zhang, Jingping; Junger, Wolfgang G

    2015-09-28

    Neutrophils use chemotaxis to locate invading bacteria. Adenosine triphosphate (ATP) release and autocrine purinergic signaling via P2Y2 receptors at the front and A2a receptors at the back of cells regulate chemotaxis. Here, we examined the intracellular mechanisms that control these opposing signaling mechanisms. We found that mitochondria deliver ATP that stimulates P2Y2 receptors in response to chemotactic cues, and that P2Y2 receptors promote mTOR signaling, which augments mitochondrial activity near the front of cells. Blocking mTOR signaling with rapamycin or PP242 or mitochondrial ATP production (e.g., with CCCP) reduced mitochondrial Ca(2+) uptake and membrane potential, and impaired cellular ATP release and neutrophil chemotaxis. Autocrine stimulation of A2a receptors causes cyclic adenosine monophosphate accumulation at the back of cells, which inhibits mTOR signaling and mitochondrial activity, resulting in uropod retraction. We conclude that mitochondrial, purinergic, and mTOR signaling regulates neutrophil chemotaxis and may be a pharmacological target in inflammatory diseases.

  1. mTOR masters monocytic myeloid-derived suppressor cells in mice with allografts or tumors

    PubMed Central

    Wu, Tingting; Zhao, Yang; Wang, Hao; Li, yang; Shao, Lijuan; Wang, Ruoyu; Lu, Jun; Yang, Zhongzhou; Wang, Junjie; Zhao, Yong

    2016-01-01

    CD11b+ Gr1+ myeloid-derived suppressor cells (MDSCs) play critical roles in controlling the processes of tumors, infections, autoimmunity and graft rejection. Immunosuppressive drug rapamycin (RPM), targeting on the key cellular metabolism molecule mTOR, is currently used in clinics to treat patients with allo-grafts, autoimmune diseases and tumors. However, the effect of RPM on MDSCs has not been studied. RPM significantly decreases the cell number and the immunosuppressive ability on T cells of CD11b+ Ly6Chigh monocytic MDSCs (M-MDSCs) in both allo-grafts-transplanted and tumor-bearing mice respectively. Mice with a myeloid-specific deletion of mTOR have poor M-MDSCs after grafting with allo-skin tissue or a tumor. Grafting of allo-skin or tumors significantly activates glycolysis pathways in myeloid precursor cells in bone marrow, which is inhibited by RPM or mTOR deletion. 2-deoxyglucose (2-DG), an inhibitor of the glycolytic pathway, inhibits M-MDSC differentiation from precursors, while enhancing glycolysis by metformin significantly rescues the RPM-caused deficiency of M-MDSCs. Therefore, we offer evidence supporting that mTOR is an intrinsic factor essential for the differentiation and immunosuppressive function of M-MDSCs and that these metabolism-relevant medicines may impact MDSCs-mediated immunosuppression or immune tolerance induction, which is of considerable clinical importance in treating graft rejection, autoimmune diseases and cancers. PMID:26833095

  2. Foxp3+ T cells inhibit antitumor immune memory modulated by mTOR inhibition.

    PubMed

    Wang, Yanping; Sparwasser, Tim; Figlin, Robert; Kim, Hyung L

    2014-04-15

    Inhibition of mTOR signaling enhances antitumor memory lymphocytes. However, pharmacologic mTOR inhibition also enhances regulatory T-cell (Treg) activity. To counter this effect, Treg control was added to mTOR inhibition in preclinical models. Tregs were controlled with CD4-depleting antibodies because CD4 depletion has high translational potential and already has a well-established safety profile in patients. The antitumor activity of the combination therapy was CD8 dependent and controlled growth of syngeneic tumors even when an adoptive immunotherapy was not used. Lymphocytes resulting from the combination therapy could be transferred into naïve mice to inhibit aggressive growth of lung metastases. The combination therapy enhanced CD8 memory formation as determined by memory markers and functional studies of immune recall. Removal of FoxP3-expressing T lymphocytes was the mechanism underlying immunologic memory formation following CD4 depletion. This was confirmed using transgenic DEREG (depletion of regulatory T cells) mice to specifically remove Foxp3(+) T cells. It was further confirmed with reciprocal studies where stimulation of immunologic memory because of CD4 depletion was completely neutralized by adoptively transferring tumor-specific Foxp3(+) T cells. Also contributing to tumor control, Tregs that eventually recovered following CD4 depletion were less immunosuppressive. These results provide a rationale for further study of mTOR inhibition and CD4 depletion in patients.

  3. Understanding translational control mechanisms of the mTOR pathway in CHO cells by polysome profiling.

    PubMed

    Courtes, Franck C; Vardy, Leah; Wong, Niki S C; Bardor, Muriel; Yap, Miranda G S; Lee, Dong-Yup

    2014-09-25

    The mammalian target of rapamycin (mTOR) pathway plays essential roles in the regulation of translational activity in many eukaryotes. Thus, from a bioprocessing point of view, understanding its molecular mechanisms may provide potential avenues for improving cell culture performance. Toward this end, the mTOR pathway of CHO cells in batch cultures was subjected to rapamycin treatment (inhibition) or nutrient supplementation (induction) and translational activities of CHO cells producing a monoclonal antibody (mAb) were evaluated with polysome profiling technology. Expectedly, rapamycin induced a shift of mRNAs from polysomes towards monosomes, thus reducing maximum cellular growth rate by 30%, while feeding additional nutrients extended mTOR pathway activity during the stationary growth phase in control batch culture, thereby contributing to an increase in global translation activity by up to 2-fold, and up to 5-fold higher specific translation of the heavy and light chains of the recombinant mAb. These increases in translation activity correlated with a 5-day extension in cellular growth and a 4-fold higher final product titer observed upon nutrient feeding. This first study of the relationship between the mTOR pathway and translational activity in CHO cultures provides key insights into the role of translational control in supporting greater productivity, which will lead to further enhancement of CHO cultures.

  4. Trichomonas vaginalis metalloproteinase induces mTOR cleavage of SiHa cells.

    PubMed

    Quan, Juan-Hua; Choi, In-Wook; Yang, Jung-Bo; Zhou, Wei; Cha, Guang-Ho; Zhou, Yu; Ryu, Jae-Sook; Lee, Young-Ha

    2014-12-01

    Trichomonas vaginalis secretes a number of proteases which are suspected to be the cause of pathogenesis; however, little is understood how they manipulate host cells. The mammalian target of rapamycin (mTOR) regulates cell growth, cell proliferation, cell motility, cell survival, protein synthesis, and transcription. We detected various types of metalloproteinases including GP63 protein from T. vaginalis trophozoites, and T. vaginalis GP63 metalloproteinase was confirmed by sequencing and western blot. When SiHa cells were stimulated with live T. vaginalis, T. vaginalis excretory-secretory products (ESP) or T. vaginalis lysate, live T. vaginalis and T. vaginalis ESP induced the mTOR cleavage in both time- and parasite load-dependent manner, but T. vaginalis lysate did not. Pretreatment of T. vaginalis with a metalloproteinase inhibitor, 1,10-phenanthroline, completely disappeared the mTOR cleavage in SiHa cells. Collectively, T. vaginalis metallopeptidase induces host cell mTOR cleavage, which may be related to survival of the parasite.

  5. mTOR Controls Ovarian Follicle Growth by Regulating Granulosa Cell Proliferation

    PubMed Central

    Yu, James; Yaba, Aylin; Kasiman, Corinna; Thomson, Travis; Johnson, Joshua

    2011-01-01

    We have shown that inhibition of mTOR in granulosa cells and ovarian follicles results in compromised granulosa proliferation and reduced follicle growth. Further analysis here using spontaneously immortalized rat granulosa cells has revealed that mTOR pathway activity is enhanced during M-phase of the cell cycle. mTOR specific phosphorylation of p70S6 kinase and 4E-BP, and expression of Raptor are all enhanced during M-phase. The predominant effect of mTOR inhibition by the specific inhibitor Rapamycin (RAP) was a dose-responsive arrest in the G1 cell cycle stage. The fraction of granulosa cells that continued to divide in the presence of RAP exhibited a dose-dependent increase in aberrant mitotic figures known as anaphase bridges. Strikingly, estradiol consistently decreased the incidence of aberrant mitotic figures. In mice treated with RAP, the mitotic index was reduced compared to controls, and a similar increase in aberrant mitotic events was noted. RAP injected during a superovulation regime resulted in a dose-dependent reduction in the numbers of eggs ovulated. Implications for the real-time regulation of follicle growth and dominance, including the consequences of increased numbers of aneuploid granulosa cells, are discussed. PMID:21750711

  6. mTOR Signaling Feedback Modulates Mammary Epithelial Differentiation and Restrains Invasion Downstream of PTEN Loss

    PubMed Central

    Ghosh, Susmita; Varela, Lidenys; Sood, Akshay; Park, Ben Ho; Lotan, Tamara L.

    2013-01-01

    Oncogenic signaling pathways are tightly regulated by negative feedback circuits and relief of these circuits represents a common mechanism of tumor drug resistance. Although the significance of these feedback pathways for signal transduction is evident, their relevance for cellular differentiation and morphogenesis in a genetically-defined context is unclear. In this study, we used isogenic benign mammary organotypic cultures to interrogate the role of mTOR-mediated negative feedback in the specific setting of PTEN inactivation. We found that mTOR signaling promoted basal-like differentiation and repressed nuclear hormone receptor expression after short-term PTEN loss in murine cell cultures analyzed ex vivo. Unexpectedly, we found that PTEN inactivation inhibited growth factor-induced epithelial invasion, and that downstream mTOR-mediated signaling feedback was both necessary and sufficient for this effect. Mechanistically, using isogenic MCF10A cells with and without somaticPTEN deletion, we showed that mTOR inhibition promoted EGF-mediated epithelial invasion by de-repressing upstream EGFR, SRC and PI3K signaling. In addition to offering new signal transduction insights, these results bring to light a number of important and potentially clinically relevant cellular consequences of mTOR inhibition in the specific context of PTEN loss, including modulation of hormone and growth factor responsiveness and promotion of epithelial invasion. Our findings prompt future investigations of the possibility that mTOR inhibitor therapy may not only be ineffective but even deleterious in tumors with PTEN loss. PMID:23774212

  7. Trichomonas vaginalis metalloproteinase induces mTOR cleavage of SiHa cells.

    PubMed

    Quan, Juan-Hua; Choi, In-Wook; Yang, Jung-Bo; Zhou, Wei; Cha, Guang-Ho; Zhou, Yu; Ryu, Jae-Sook; Lee, Young-Ha

    2014-12-01

    Trichomonas vaginalis secretes a number of proteases which are suspected to be the cause of pathogenesis; however, little is understood how they manipulate host cells. The mammalian target of rapamycin (mTOR) regulates cell growth, cell proliferation, cell motility, cell survival, protein synthesis, and transcription. We detected various types of metalloproteinases including GP63 protein from T. vaginalis trophozoites, and T. vaginalis GP63 metalloproteinase was confirmed by sequencing and western blot. When SiHa cells were stimulated with live T. vaginalis, T. vaginalis excretory-secretory products (ESP) or T. vaginalis lysate, live T. vaginalis and T. vaginalis ESP induced the mTOR cleavage in both time- and parasite load-dependent manner, but T. vaginalis lysate did not. Pretreatment of T. vaginalis with a metalloproteinase inhibitor, 1,10-phenanthroline, completely disappeared the mTOR cleavage in SiHa cells. Collectively, T. vaginalis metallopeptidase induces host cell mTOR cleavage, which may be related to survival of the parasite. PMID:25548410

  8. mTOR and differential activation of mitochondria orchestrate neutrophil chemotaxis

    PubMed Central

    Bao, Yi; Ledderose, Carola; Graf, Amelie F.; Brix, Bianca; Birsak, Theresa; Lee, Albert; Zhang, Jingping

    2015-01-01

    Neutrophils use chemotaxis to locate invading bacteria. Adenosine triphosphate (ATP) release and autocrine purinergic signaling via P2Y2 receptors at the front and A2a receptors at the back of cells regulate chemotaxis. Here, we examined the intracellular mechanisms that control these opposing signaling mechanisms. We found that mitochondria deliver ATP that stimulates P2Y2 receptors in response to chemotactic cues, and that P2Y2 receptors promote mTOR signaling, which augments mitochondrial activity near the front of cells. Blocking mTOR signaling with rapamycin or PP242 or mitochondrial ATP production (e.g., with CCCP) reduced mitochondrial Ca2+ uptake and membrane potential, and impaired cellular ATP release and neutrophil chemotaxis. Autocrine stimulation of A2a receptors causes cyclic adenosine monophosphate accumulation at the back of cells, which inhibits mTOR signaling and mitochondrial activity, resulting in uropod retraction. We conclude that mitochondrial, purinergic, and mTOR signaling regulates neutrophil chemotaxis and may be a pharmacological target in inflammatory diseases. PMID:26416965

  9. Combined inhibition of MEK and mTOR has a synergic effect on angiosarcoma tumorgrafts.

    PubMed

    Andersen, Nicholas J; Boguslawski, Elissa B; Kuk, Cynthia Y; Chambers, Christopher M; Duesbery, Nicholas S

    2015-07-01

    Angiosarcoma (AS) is a rare neoplasm of endothelial origin that has limited treatment options and poor five-year survival. Using tumorgraft models, we previously showed that AS is sensitive to small-molecule inhibitors that target mitogen-activated/extracellular-signal-regulated protein kinase kinases 1 and 2 (MEK). The objective of this study was to identify drugs that combine with MEK inhibitors to more effectively inhibit AS growth. We examined the in vitro synergy between the MEK inhibitor PD0325901 and inhibitors of eleven common cancer pathways in melanoma cell lines and canine angiosarcoma cell isolates. Combination indices were calculated using the Chou-Talalay method. Optimized combination therapies were evaluated in vivo for toxicity and efficacy using canine angiosarcoma tumorgrafts. Among the drugs we tested, rapamycin stood out because it showed strong synergy with PD0325901 at nanomolar concentrations. We observed that angiosarcomas are insensitive to mTOR inhibition. However, treatment with nanomolar levels of mTOR inhibitor renders these cells as sensitive to MEK inhibition as a melanoma cell line with mutant BRAF. Similar results were observed in B-Raf wild-type melanoma cells as well as in vivo, where treatment of canine AS tumorgrafts with MEK and mTOR inhibitors was more effective than monotherapy. Our data show that a low dose of an mTOR inhibitor can dramatically enhance angiosarcoma and melanoma response to MEK inhibition, potentially widening the field of applications for MEK-targeted therapy. PMID:25955301

  10. The Role and Regulation of mTOR in T Lymphocyte Function

    PubMed Central

    O’Brien, Thomas F.; Zhong, Xiao-Ping

    2012-01-01

    The conversion of naïve T cells into effector T cells is initiated by stimulation through the T cell receptor (TCR). Upon activation, T cells undergo significant morphological and functional changes, putting new metabolic demands on the cell. Past research has identified the mammalian target of rapamycin (mTOR) as a critical regulator of cell metabolism, and the development of new genetic models has begun to reveal an important role for this pathway in the homeostasis and function of T lymphocytes. In this review we focus on the most recent findings that demonstrate the ability of the mTOR to regulate T cell activation, CD8+ memory cell formation and function, and helper T lineage differentiation. We highlight the importance of tight control of mTOR signaling by the tuberous sclerosis complex 1 for T cell homeostasis. Finally, we discuss the regulation of mTOR signaling by diacylglycerol kinases and the RasGRP1-Ras-Erk1/2 pathway in the context of TCR signaling. PMID:22484804

  11. mTOR regulates MAPKAPK2 translation to control the senescence-associated secretory phenotype

    PubMed Central

    Herranz, Nicolás; Gallage, Suchira; Mellone, Massimiliano; Wuestefeld, Torsten; Klotz, Sabrina; Hanley, Christopher J.; Raguz, Selina; Acosta, Juan Carlos; Innes, Andrew J; Banito, Ana; Georgilis, Athena; Montoya, Alex; Wolter, Katharina; Dharmalingam, Gopuraja; Faull, Peter; Carroll, Thomas; Martínez-Barbera, Juan Pedro; Cutillas, Pedro; Reisinger, Florian; Heikenwalder, Mathias; Miller, Richard A.; Withers, Dominic; Zender, Lars; Thomas, Gareth J.; Gil, Jesús

    2015-01-01

    Senescent cells secrete a combination of factors collectively known as the senescence-associated secretory phenotype (SASP). The SASP reinforces senescence and activates an immune surveillance response but it can also display pro-tumorigenic properties and contribute to age-related pathologies. In a drug screen to find novel SASP regulators, we uncovered the mTOR inhibitor rapamycin as a potent SASP suppressor. Here we report a mechanism by which mTOR controls the SASP by differentially regulating the translation of the MK2/MAPKAPK2 kinase through 4EBP1. In turn, MAPKAPK2 phosphorylates the RNA binding protein ZFP36L1 during senescence, inhibiting its ability to degrade the transcripts of numerous SASP components. Consequently, mTOR inhibition or constitutive activation of ZFP36L1 impairs the non-cell-autonomous effects of senescent cells both in tumour-suppressive and promoting-promoting contexts. Altogether, our results place regulation of the SASP as a key mechanism by which mTOR could influence cancer, age-related diseases and immune responses. PMID:26280535

  12. Learning from the Cardiologists and Developing Eluting Stents Targeting the Mtor Pathway for Pulmonary Application; A Future Concept for Tracheal Stenosis

    PubMed Central

    Zarogoulidis, Paul; Darwiche, Kaid; Tsakiridis, Kosmas; Teschler, Helmut; Yarmus, Lonny; Zarogoulidis, Konstantinos; Freitag, Lutz

    2014-01-01

    Tracheal stenosis due to either benign or malignant disease is a situation that the pulmonary physicians and thoracic surgeons have to cope in their everyday clinical practice. In the case where tracheal stenosis is caused due to malignancy mini-interventional interventions with laser, apc, cryoprobe, balloon dilation or with combination of more than one equipment and technique can be used. On the other hand, in the case of a benign disease such as; tracheomalacia the clinician can immediately upon diagnosis proceed to the stent placement. In both situations however; it has been observed that the stents induce formation of granuloma tissue in both or one end of the stent. Therefore a frequent evaluation of the patient is necessary, taking also into account the nature of the primary disease. Evaluation methodologies identifying different types and extent of the trachea stenosis have been previously published. However; we still do not have an effective adjuvant therapy to prevent granuloma tissue formation or prolong already treated granuloma lesions. There have been proposed many mechanisms which induce the abnormal growth of the local tissue, such as; local pressure, local stress, inflammation and vascular endothelial growth factor overexpression. Immunomodulatory agents inhibiting the mTOR pathway are capable of inhibiting the inflammatory cascade locally. In the current mini-review we will try to present the current knowledge of drug eluting stents inhibiting the mTOR pathway and propose a future application of these stents as a local anti-proliferative treatment. PMID:24454525

  13. Hyperactive mTOR signals in the proopiomelanocortin-expressing hippocampal neurons cause age-dependent epilepsy and premature death in mice

    PubMed Central

    Matsushita, Yuki; Sakai, Yasunari; Shimmura, Mitsunori; Shigeto, Hiroshi; Nishio, Miki; Akamine, Satoshi; Sanefuji, Masafumi; Ishizaki, Yoshito; Torisu, Hiroyuki; Nakabeppu, Yusaku; Suzuki, Akira; Takada, Hidetoshi; Hara, Toshiro

    2016-01-01

    Epilepsy is a frequent comorbidity in patients with focal cortical dysplasia (FCD). Recent studies utilizing massive sequencing data identified subsets of genes that are associated with epilepsy and FCD. AKT and mTOR-related signals have been recently implicated in the pathogenic processes of epilepsy and FCD. To clarify the functional roles of the AKT-mTOR pathway in the hippocampal neurons, we generated conditional knockout mice harboring the deletion of Pten (Pten-cKO) in Proopiomelanocortin-expressing neurons. The Pten-cKO mice developed normally until 8 weeks of age, then presented generalized seizures at 8–10 weeks of age. Video-monitored electroencephalograms detected paroxysmal discharges emerging from the cerebral cortex and hippocampus. These mice showed progressive hypertrophy of the dentate gyrus (DG) with increased expressions of excitatory synaptic markers (Psd95, Shank3 and Homer). In contrast, the expression of inhibitory neurons (Gad67) was decreased at 6–8 weeks of age. Immunofluorescence studies revealed the abnormal sprouting of mossy fibers in the DG of the Pten-cKO mice prior to the onset of seizures. The treatment of these mice with an mTOR inhibitor rapamycin successfully prevented the development of seizures and reversed these molecular phenotypes. These data indicate that the mTOR pathway regulates hippocampal excitability in the postnatal brain. PMID:26961412

  14. Compensatory activation of Akt in response to mTOR and Raf inhibitors - a rationale for dual-targeted therapy approaches in neuroendocrine tumor disease.

    PubMed

    Zitzmann, Kathrin; Rüden, Janina von; Brand, Stephan; Göke, Burkhard; Lichtl, Jennifer; Spöttl, Gerald; Auernhammer, Christoph J

    2010-09-01

    Several studies have established a link between aberrant PI(3)K-Akt-mTOR- and Ras-Raf-MEK-Erk1/2 signaling and neuroendocrine tumor disease. In this study, we comparatively investigate the antitumor potential of novel small-molecule inhibitors targeting mTOR (RAD001), mTOR/PI(3)K (NVP-BEZ235) and Raf (Raf265) on human NET cell lines of heterogeneous origin. All inhibitors induced potent antitumor effects which involved the induction of apoptosis and G0/G1 arrest. However, the dual mTOR/PI(3)K inhibitor NVP-BEZ235 was more efficient compared to the single mTOR inhibitor RAD001. Consistently, NVP-BEZ235 prevented the negative feedback activation of Akt as observed after treatment with RAD001. Raf265 inhibited Erk1/2 phosphorylation but strongly induced Akt phosphorylation and VEGF secretion, suggesting the existence of a compensatory feedback loop on PI3K-Akt signaling. Finally, combined treatment with RAD001 or NVP-BEZ235 and Raf265 was more efficient than single treatment with either kinase inhibitor. Together, our data provide a rationale for dual targeting of PI(3)K-Akt-mTOR- and Ras-Raf-MEK-Erk1/2 signaling in NET disease.

  15. Kinome RNAi Screens Reveal Synergistic Targeting of MTOR and FGFR1 Pathways for Treatment of Lung Cancer and HNSCC.

    PubMed

    Singleton, Katherine R; Hinz, Trista K; Kleczko, Emily K; Marek, Lindsay A; Kwak, Jeff; Harp, Taylor; Kim, Jihye; Tan, Aik Choon; Heasley, Lynn E

    2015-10-15

    The FGFR1 is a therapeutic target under investigation in multiple solid tumors and clinical trials of selective tyrosine kinase inhibitors (TKI) are underway. Treatment with a single TKI represents a logical step toward personalized cancer therapy, but intrinsic and acquired resistance mechanisms limit their long-term benefit. In this study, we deployed RNAi-based functional genomic screens to identify protein kinases controlling the intrinsic sensitivity of FGFR1-dependent lung cancer and head and neck squamous cell cancer (HNSCC) cells to ponatinib, a multikinase FGFR-active inhibitor. We identified and validated a synthetic lethal interaction between MTOR and ponatinib in non-small cell lung carcinoma cells. In addition, treatment with MTOR-targeting shRNAs and pharmacologic inhibitors revealed that MTOR is an essential protein kinase in other FGFR1-expressing cancer cells. The combination of FGFR inhibitors and MTOR or AKT inhibitors resulted in synergistic growth suppression in vitro. Notably, tumor xenografts generated from FGFR1-dependent lung cancer cells exhibited only modest sensitivity to monotherapy with the FGFR-specific TKI, AZD4547, but when combined with the MTOR inhibitor, AZD2014, significantly attenuated tumor growth and prolonged survival. Our findings support the existence of a signaling network wherein FGFR1-driven ERK and activated MTOR/AKT represent distinct arms required to induce full transformation. Furthermore, they suggest that clinical efficacy of treatments for FGFR1-driven lung cancers and HNSCC may be achieved by combining MTOR inhibitors and FGFR-specific TKIs. PMID:26359452

  16. mTOR signaling in aging and neurodegeneration: At the crossroad between metabolism dysfunction and impairment of autophagy.

    PubMed

    Perluigi, Marzia; Di Domenico, Fabio; Butterfield, D Allan

    2015-12-01

    Compelling evidence indicates that the mammalian target of rapamycin (mTOR) signaling pathway is involved in cellular senescence, organismal aging and age-dependent diseases. mTOR is a conserved serine/threonine kinase that is known to be part of two different protein complexes: mTORC1 and mTORC2, which differ in some components and in upstream and downstream signalling. In multicellular organisms, mTOR regulates cell growth and metabolism in response to nutrients, growth factors and cellular energy conditions. Growing studies highlight that disturbance in mTOR signalling in the brain affects multiple pathways including glucose metabolism, energy production, mitochondrial function, cell growth and autophagy. All these events are key players in age-related cognitive decline such as development of Alzheimer disease (AD). The current review discusses the main regulatory roles of mTOR signalling in the brain, in particular focusing on autophagy, glucose metabolism and mitochondrial functions. Targeting mTOR in the CNS can offer new prospective for drug discovery; however further studies are needed for a comprehensive understanding of mTOR, which lies at the crossroads of multiple signals involved in AD etiology and pathogenesis.

  17. Fluoxetine regulates mTOR signalling in a region-dependent manner in depression-like mice

    PubMed Central

    Liu, Xiao-Long; Luo, Liu; Mu, Rong-Hao; Liu, Bin-Bin; Geng, Di; Liu, Qing; Yi, Li-Tao

    2015-01-01

    Previous studies have demonstrated that the mammalian target of rapamycin (mTOR) signaling pathway has an important role in ketamine-induced, rapid antidepressant effects despite the acute administration of fluoxetine not affecting mTOR phosphorylation in the brain. However, the effects of long-term fluoxetine treatment on mTOR modulation have not been assessed to date. In the present study, we examined whether fluoxetine, a type of commonly used antidepressant agent, alters mTOR signaling following chronic administration in different brain regions, including the frontal cortex, hippocampus, amygdala and hypothalamus. We also investigated whether fluoxetine enhanced synaptic protein levels in these regions via the activation of the mTOR signaling pathway and its downstream regulators, p70S6K and 4E-BP-1. The results indicated that chronic fluoxetine treatment attenuated the chronic, unpredictable, mild stress (CUMS)-induced mTOR phosphorylation reduction in the hippocampus and amygdala of mice but not in the frontal cortex or the hypothalamus. Moreover, the CUMS-decreased PSD-95 and synapsin I levels were reversed by fluoxetine, and these effects were blocked by rapamycin only in the hippocampus. In conclusion, our findings suggest that chronic treatment with fluoxetine can induce synaptic protein expression by activating the mTOR signaling pathway in a region-dependent manner and mainly in the hippocampus. PMID:26522512

  18. Fluoxetine regulates mTOR signalling in a region-dependent manner in depression-like mice.

    PubMed

    Liu, Xiao-Long; Luo, Liu; Mu, Rong-Hao; Liu, Bin-Bin; Geng, Di; Liu, Qing; Yi, Li-Tao

    2015-01-01

    Previous studies have demonstrated that the mammalian target of rapamycin (mTOR) signaling pathway has an important role in ketamine-induced, rapid antidepressant effects despite the acute administration of fluoxetine not affecting mTOR phosphorylation in the brain. However, the effects of long-term fluoxetine treatment on mTOR modulation have not been assessed to date. In the present study, we examined whether fluoxetine, a type of commonly used antidepressant agent, alters mTOR signaling following chronic administration in different brain regions, including the frontal cortex, hippocampus, amygdala and hypothalamus. We also investigated whether fluoxetine enhanced synaptic protein levels in these regions via the activation of the mTOR signaling pathway and its downstream regulators, p70S6K and 4E-BP-1. The results indicated that chronic fluoxetine treatment attenuated the chronic, unpredictable, mild stress (CUMS)-induced mTOR phosphorylation reduction in the hippocampus and amygdala of mice but not in the frontal cortex or the hypothalamus. Moreover, the CUMS-decreased PSD-95 and synapsin I levels were reversed by fluoxetine, and these effects were blocked by rapamycin only in the hippocampus. In conclusion, our findings suggest that chronic treatment with fluoxetine can induce synaptic protein expression by activating the mTOR signaling pathway in a region-dependent manner and mainly in the hippocampus.

  19. Screening mTOR siRNA based on bioinformatics and detecting the transcription by the gold nanoparticle beacon

    NASA Astrophysics Data System (ADS)

    Tian, Caiping; Ma, Yi; Li, Siwen; Gu, Yueqing

    2014-09-01

    Mammalian target of rapamycin (mTOR) as a key protein in PI3K-AKT-mTOR signaling pathway ,plays an important role in the tumor growth. The small interfering RNA (siRNA) of mTOR would decrease the expression of mTOR protein. In this study, we screened the mTOR siRNA sequence using MATLAB software and ascertained it based on BLAST. Then we imported it with the aid of Lipofectamine2000 into MCF-7 cancer cells where mTOR is over expression .And then we used a special hairpin deoxyribonucleic acid (DNA) for combining with the human mTOR mRNA to functionalize gold nanoparticles, which served as a molecule beacon for detecting human mTOR mRNA transcription. Laser scanning confocal microscope and Flow Cytometry data showed that the quenching efficiency was up to 90%,which are consistent with the RT-PCR measurement and Western. Compared to the previous approaches, this beacon has advantages of higher target to background ratio of detection. The strategy reported in this study is a promising approach for the intracellular measurement of the result of siRNA or protein expression in living cells, and has great potential in the study of drug screening and discovery.

  20. Fast LC-MS/MS analysis of tacrolimus, sirolimus, everolimus and cyclosporin A in dried blood spots and the influence of the hematocrit and immunosuppressant concentration on recovery.

    PubMed

    Koster, Remco A; Alffenaar, Jan-Willem C; Greijdanus, Ben; Uges, Donald R A

    2013-10-15

    We developed a method for the analysis of four immunosuppressants in dried blood spot (DBS) samples to facilitate therapeutic drug monitoring for transplant patients outside the hospital. An 8mm disc from the central part of the DBS was punched, extracted and followed by LC-MS/MS analysis. The method was validated with ranges from 1.00-50.0 µg/L for tacrolimus, sirolimus and everolimus, and from 20.0-2000 µg/L for cyclosporin A. The validation showed a maximum overall bias of 13.0% for the sirolimus LLOQ, while the maximum overall CV was 15.7% for the everolimus LLOQ. All four immunosuppressants showed to be stable in DBS for at least 7 days at 22°C. The volume of the blood spot showed to have minor effect on measured concentrations. A cross-validation test between the 31 ET CHR paper and the Whatman FTA DMPK-C cards showed no significant difference between the two types of paper. During validation the hematocrit (HT) showed to have significant influence on the analytical results. When the measured concentrations were corrected for the effect of the HT, biases improved significantly. Additional recovery tests proved that the combination of especially low HT and high concentration does not only affect the spot size but can also affect the extraction recoveries of sirolimus and especially everolimus. Although the tested parameters like HT and concentrations are extreme and unlikely for routine analysis of outpatients, the fundamental effect of the combination of these parameters on extraction recoveries are proven with this research. The protein binding in the blood and hydrogen binding to the cellulose of the paper is suggested to influence extractions and gives new insights in the extraction methodology of DBS samples. The observed HT effect during the validation appeared to be negligible during the correlation study as no concentration corrections for the HT values were needed. Nevertheless, results from DBS samples with extremely high concentrations combined

  1. Distinct amino acid-sensing mTOR pathways regulate skeletal myogenesis.

    PubMed

    Yoon, Mee-Sup; Chen, Jie

    2013-12-01

    Signaling through the mammalian target of rapamycin (mTOR) in response to amino acid availability controls many cellular and developmental processes. mTOR is a master regulator of myogenic differentiation, but the pathways mediating amino acid signals in this process are not known. Here we examine the Rag GTPases and the class III phosphoinositide 3-kinase (PI3K) Vps34, two mediators of amino acid signals upstream of mTOR complex 1 (mTORC1) in cell growth regulation, for their potential involvement in myogenesis. We find that, although both Rag and Vps34 mediate amino acid activation of mTORC1 in C2C12 myoblasts, they have opposing functions in myogenic differentiation. Knockdown of RagA/B enhances, whereas overexpression of active RagB/C mutants impairs, differentiation, and this inhibitory function of Rag is mediated by mTORC1 suppression of the IRS1-PI3K-Akt pathway. On the other hand, Vps34 is required for myogenic differentiation. Amino acids activate a Vps34-phospholipase D1 (PLD1) pathway that controls the production of insulin-like growth factor II, an autocrine inducer of differentiation, through the Igf2 muscle enhancer. The product of PLD, phosphatidic acid, activates the enhancer in a rapamycin-sensitive but mTOR kinase-independent manner. Our results uncover amino acid-sensing mechanisms controlling the homeostasis of myogenesis and underline the versatility and context dependence of mTOR signaling. PMID:24068326

  2. Inhibition of class I histone deacetylases blunts cardiac hypertrophy through TSC2-dependent mTOR repression

    PubMed Central

    Morales, Cyndi R.; Li, Dan L.; Pedrozo, Zully; May, Herman I.; Jiang, Nan; Kyrychenko, Viktoriia; Cho, Geoffrey; Kim, Soo Young; Wang, Zhao V.; Rotter, David; Rothermel, Beverly A.; Schneider, Jay W.; Lavandero, Sergio; Gillette, Thomas G.; Hill, Joseph A.

    2016-01-01

    Altering chromatin structure through histone posttranslational modifications has emerged as a key driver of transcriptional responses in cells. Modulation of these transcriptional responses by pharmacological inhibition of class I histone deacetylases (HDACs), a group of chromatin remodeling enzymes, has been successful in blocking the growth of some cancer cell types. These inhibitors also attenuate the pathogenesis of pathological cardiac remodeling by blunting and even reversing pathological hypertrophy. The mechanistic target of rapamycin (mTOR) is a critical sensor and regulator of cell growth that as part of mTOR complex I (mTORC1) drives changes in protein synthesis and metabolism in both pathological and physiological hypertrophy. Here, we demonstrated through pharmacological and genetic methods that inhibition of class I HDACs suppressed pathological cardiac hypertrophy through inhibition of mTOR activity. Mice genetically silenced for HDAC1 and HDAC2 had a reduced hypertrophic response to TAC and showed reduced mTOR activity. We determined that the abundance of tuberous sclerosis complex 2 (TSC2), an mTOR inhibitor, was increased through a transcriptional mechanism in cardiomyocytes when class I HDACs were inhibited. In neonatal rat cardiomyocytes, loss of TSC2 abolished HDAC-dependent inhibition of mTOR activity, and increased expression of TSC2 was sufficient to reduce hypertrophy in response to phenylephrine. These findings point to mTOR and TSC2-dependent control of mTOR as critical components of the mechanism by which HDAC inhibitors blunt pathological cardiac growth. These results also suggest a strategy to modulate mTOR activity and facilitate the translational exploitation of HDAC inhibitors in heart disease. PMID:27048565

  3. p53 inhibition provides a pivotal protective effect against ischemia-reperfusion injury in vitro via mTOR signaling.

    PubMed

    Li, Xiaomu; Gu, Shixin; Ling, Yan; Shen, Chao; Cao, Xiaoyun; Xie, Rong

    2015-04-24

    Tumor suppressor p53 has recently been reported to have numerous functions independent of tumorigenesis, including neuronal survival during ischemia. The mammalian target of rapamycin (mTOR) signaling pathway plays a central role in the regulation of metabolism, cell growth, development, and cell survival. Our recent work has demonstrated the neuroprotective effects of the mTOR pathway. Considering that p53 is also an important regulator of mTOR, to further clarify the role of p53 and the mTOR signaling pathway in neuronal ischemic-reperfusion injury, we used mouse primary mixed cultured neurons with an oxygen glucose deprivation (OGD) model to mimic an ischemic-reperfusion injury in vitro. A lentiviral system was also used to inhibit or overexpress p53 to determine whether p53 alteration affects OGD and reperfusion injury. Our results show that activated p53 was induced and it suppressed mTOR expression in primary mixed cultured neurons after OGD and reperfusion. Inhibiting p53, using either a chemical inhibitor or lentiviral-mediated shRNA, exhibited neuroprotective effects in primary cultured neurons against OGD and reperfusion injury through the upregulation of mTOR activity. Such protective effects could be reversed by rapamycin, an mTOR inhibitor. Conversely, p53 overexpression tended to exacerbate the detrimental effects of OGD injury by downregulating mTOR activity. These results suggest that p53 inhibition has a pivotal protective effect against an in vitro ischemia-reperfusion injury via mTOR signaling and provides a potential and promising therapeutic target for stroke treatment. PMID:25681550

  4. Improved oral absorption and chemical stability of everolimus via preparation of solid dispersion using solvent wetting technique.

    PubMed

    Jang, Sun Woo; Kang, Myung Joo

    2014-10-01

    The aim of this study was to improve the physicochemical properties and oral absorption of poorly water-soluble everolimus via preparation of a solid dispersion (SD) system using a solvent wetting (SW) technique. The physicochemical properties, drug release profile, and bioavailability of SD prepared by SW process were also compared to SD prepared by the conventional co-precipitation method. Solid state characterizations using scanning electron microscopy, particle size analysis and X-ray powder diffraction indicated that drug homogeneously dispersed and existed in an amorphous state within the intact polymeric carrier. Whereas, a film-like mass was obtained by a co-precipitation method and further pulverization step was needed for tabletization. The drug release from the SD tablet prepared by SW process at a ratio of drug to hydroxypropyl methylcellulose of 1:15 was markedly higher than the drug alone and equivalent to the marketed product (Afinitor(®), Novartis Pharmaceuticals), a SD tablet prepared by co-precipitation method, archiving over 75% the drug release after 30 min. At the accelerated (40°C/75% R.H.) and stress (80°C) stability tests, the novel formula was more stable than drug powder and provided comparable drug stability with the commercially available product, which contains a potentially risky antioxidant, butylated hydroxyl toluene. The pharmacokinetic parameters after single oral administration in beagles showed no significant difference (P>0.01) between the novel SD-based tablet and the marketed product. The results of this study, therefore, suggest that the novel SD system prepared by the solvent wetting process may be a promising approach for improving the physicochemical stability and oral absorption of the sirolimus derivatives. PMID:25003829

  5. Glycerol-3-phosphate acyltransferase-1 upregulation by O-GlcNAcylation of Sp1 protects against hypoxia-induced mouse embryonic stem cell apoptosis via mTOR activation

    PubMed Central

    Lee, H J; Ryu, J M; Jung, Y H; Lee, K H; Kim, D I; Han, H J

    2016-01-01

    Oxygen signaling is critical for stem cell regulation, and oxidative stress-induced stem cell apoptosis decreases the efficiency of stem cell therapy. Hypoxia activates O-linked β-N-acetyl glucosaminylation (O-GlcNAcylation) of stem cells, which contributes to regulation of cellular metabolism, as well as cell fate. Our study investigated the role of O-GlcNAcylation via glucosamine in the protection of hypoxia-induced apoptosis of mouse embryonic stem cells (mESCs). Hypoxia increased mESCs apoptosis in a time-dependent manner. Moreover, hypoxia also slightly increased the O-GlcNAc level. Glucosamine treatment further enhanced the O-GlcNAc level and prevented hypoxia-induced mESC apoptosis, which was suppressed by O-GlcNAc transferase inhibitors. In addition, hypoxia regulated several lipid metabolic enzymes, whereas glucosamine increased expression of glycerol-3-phosphate acyltransferase-1 (GPAT1), a lipid metabolic enzyme producing lysophosphatidic acid (LPA). In addition, glucosamine-increased O-GlcNAcylation of Sp1, which subsequently leads to Sp1 nuclear translocation and GPAT1 expression. Silencing of GPAT1 by gpat1 siRNA transfection reduced glucosamine-mediated anti-apoptosis in mESCs and reduced mammalian target of rapamycin (mTOR) phosphorylation. Indeed, LPA prevented mESCs from undergoing hypoxia-induced apoptosis and increased phosphorylation of mTOR and its substrates (S6K1 and 4EBP1). Moreover, mTOR inactivation by rapamycin (mTOR inhibitor) increased pro-apoptotic proteins expressions and mESC apoptosis. Furthermore, transplantation of non-targeting siRNA and glucosamine-treated mESCs increased cell survival and inhibited flap necrosis in mouse skin flap model. Conversely, silencing of GPAT1 expression reversed those glucosamine effects. In conclusion, enhancing O-GlcNAcylation of Sp1 by glucosamine stimulates GPAT1 expression, which leads to inhibition of hypoxia-induced mESC apoptosis via mTOR activation. PMID:27010859

  6. [An Elderly Patient with Metastatic Breast Cancer Who Developed Severe Adverse Events such as Stomatitis and Interstitial Pneumonia after Everolimus plus Exemestane Treatment].

    PubMed

    Sakiyama, Kana; Yoshida, Takashi; Goto, Yoshinari; Kimura, Morihiko

    2016-06-01

    An 80-year-old woman was diagnosed with right breast cancer with clinical Stage IIIA 6 years previously. She underwent mastectomy and axillary lymph node dissection. The pathological diagnosis was invasive micropapillary carcinoma with lymph node involvement. Immunohistochemically, the tumor was positive for estrogen receptor and progesterone receptor, and negative for HER2. Postoperatively, the patient was treated with adjuvant chemotherapy consisting of cyclophosphamide, epirubicin, 5-fluorouracil, and paclitaxel, followed by endocrine therapy with letrozole. Four years after surgery, she experienced a recurrence of breast cancer in the thoracic wall, and was treated with exemestane, toremifene, and fulvestrant for 1 year and 5 months. However, she developed carcinomatous pleurisy and was treated with eribulin. This last treatment was ineffective. Subsequently, she received combination therapy with everolimus and exemestane. Although the pleural effusion reduced markedly after 5 weeks, stomatitis, diarrhea, melena, and interstitial pneumonia occurred as adverse events. The symptoms improved after drug discontinuation and steroid therapy. The combination therapy with everolimus and exemestane is a prospective therapy for hormone-resistant recurrent breast cancer, but the management of adverse events is very important. PMID:27306814

  7. Characterization of Torin2, an ATP-competitive inhibitor of mTOR, ATM, and ATR.

    PubMed

    Liu, Qingsong; Xu, Chunxiao; Kirubakaran, Sivapriya; Zhang, Xin; Hur, Wooyoung; Liu, Yan; Kwiatkowski, Nicholas P; Wang, Jinhua; Westover, Kenneth D; Gao, Peng; Ercan, Dalia; Niepel, Mario; Thoreen, Carson C; Kang, Seong A; Patricelli, Matthew P; Wang, Yuchuan; Tupper, Tanya; Altabef, Abigail; Kawamura, Hidemasa; Held, Kathryn D; Chou, Danny M; Elledge, Stephen J; Janne, Pasi A; Wong, Kwok-Kin; Sabatini, David M; Gray, Nathanael S

    2013-04-15

    mTOR is a highly conserved serine/threonine protein kinase that serves as a central regulator of cell growth, survival, and autophagy. Deregulation of the PI3K/Akt/mTOR signaling pathway occurs commonly in cancer and numerous inhibitors targeting the ATP-binding site of these kinases are currently undergoing clinical evaluation. Here, we report the characterization of Torin2, a second-generation ATP-competitive inhibitor that is potent and selective for mTOR with a superior pharmacokinetic profile to previous inhibitors. Torin2 inhibited mTORC1-dependent T389 phosphorylation on S6K (RPS6KB1) with an EC(50) of 250 pmol/L with approximately 800-fold selectivity for cellular mTOR versus phosphoinositide 3-kinase (PI3K). Torin2 also exhibited potent biochemical and cellular activity against phosphatidylinositol-3 kinase-like kinase (PIKK) family kinases including ATM (EC(50), 28 nmol/L), ATR (EC(50), 35 nmol/L), and DNA-PK (EC(50), 118 nmol/L; PRKDC), the inhibition of which sensitized cells to Irradiation. Similar to the earlier generation compound Torin1 and in contrast to other reported mTOR inhibitors, Torin2 inhibited mTOR kinase and mTORC1 signaling activities in a sustained manner suggestive of a slow dissociation from the kinase. Cancer cell treatment with Torin2 for 24 hours resulted in a prolonged block in negative feedback and consequent T308 phosphorylation on Akt. These effects were associated with strong growth inhibition in vitro. Single-agent treatment with Torin2 in vivo did not yield significant efficacy against KRAS-driven lung tumors, but the combination of Torin2 with mitogen-activated protein/extracellular signal-regulated kinase (MEK) inhibitor AZD6244 yielded a significant growth inhibition. Taken together, our findings establish Torin2 as a strong candidate for clinical evaluation in a broad number of oncologic settings where mTOR signaling has a pathogenic role.

  8. Oncological Impact of M-Tor Inhibitor Immunosuppressive Therapy after Liver Transplantation for Hepatocellular Carcinoma: Review of the Literature

    PubMed Central

    Tarantino, Giuseppe; Magistri, Paolo; Ballarin, Roberto; Di Francia, Raffaele; Berretta, Massimiliano; Di Benedetto, Fabrizio

    2016-01-01

    Background: Hepatocellular Carcinoma (HCC) represents the fifth most common malignancy and the third cancer-related cause of death worldwide. Hepatitis B (HBV) and C (HCV) viral infections and alcohol abuse are the principal etiological factors for HCC. Liver transplantation (LT) is oncologically the preferable approach to HCC, as it can remove all the intrahepatic tumor foci, and also the oncogenic cirrhotic liver. The use of mTOR inhibitors (mTORi) for immunosuppression after LT for HCC has been proposed due to rapamycin antitumor activity. We decided to review the literature to clarify the oncological role of mTORi after liver transplantation for HCC, analyzing both present condition and future perspectives. Material and Methods: A systematic literature search was performed using PubMed, EMBASE, Scopus, and the Cochrane Library Central. The search was limited to studies in humans and to those reported in the English language in the period of time between January 2005 and December 2015. Results: The literature search yielded 93 articles; after duplicates were removed, 77 titles and abstracts were reviewed. Most relevant data and papers are herein reported and discussed. Conclusions: So far, the use of mTORi is encouraging in terms of oncological outcomes for patients underwent LT for HCC, both for prevention and treatment of HCC recurrence although definitive data are still awaited.

  9. eIF4GI links nutrient sensing by mTOR to cell proliferation and inhibition of autophagy

    PubMed Central

    Ramírez-Valle, Francisco; Braunstein, Steve; Zavadil, Jiri; Formenti, Silvia C.; Schneider, Robert J.

    2008-01-01

    Translation initiation factors have complex functions in cells that are not yet understood. We show that depletion of initiation factor eIF4GI only modestly reduces overall protein synthesis in cells, but phenocopies nutrient starvation or inhibition of protein kinase mTOR, a key nutrient sensor. eIF4GI depletion impairs cell proliferation, bioenergetics, and mitochondrial activity, thereby promoting autophagy. Translation of mRNAs involved in cell growth, proliferation, and bioenergetics were selectively inhibited by reduction of eIF4GI, as was the mRNA encoding Skp2 that inhibits p27, whereas catabolic pathway factors were increased. Depletion or overexpression of other eIF4G family members did not recapitulate these results. The majority of mRNAs that were translationally impaired with eIF4GI depletion were excluded from polyribosomes due to the presence of multiple upstream open reading frames and low mRNA abundance. These results suggest that the high levels of eIF4GI observed in many breast cancers might act to specifically increase proliferation, prevent autophagy, and release tumor cells from control by nutrient sensing. PMID:18426977

  10. MTOR regulates the pro-tumorigenic senescence-associated secretory phenotype by promoting IL1A translation

    PubMed Central

    Laberge, Remi-Martin; Sun, Yu; Orjalo, Arturo V.; Patil, Christopher K.; Freund, Adam; Zhou, Lili; Curran, Samuel C.; Davalos, Albert R.; Wilson-Edell, Kathleen A.; Liu, Su; Limbad, Chandani; Demaria, Marco; Li, Patrick; Hubbard, Gene B.; Ikeno, Yuji; Javors, Martin; Desprez, Pierre-Yves; Benz, Christopher C.; Kapahi, Pankaj; Nelson, Peter S.; Campisi, Judith

    2015-01-01

    The TOR (target of rapamycin) kinase limits longevity by poorly understood mechanisms. Rapamycin suppresses the mammalian TORC1 complex, which regulates translation, and extends lifespan in diverse species, including mice. We show that rapamycin selectively blunts the pro-inflammatory phenotype of senescent cells. Cellular senescence suppresses cancer by preventing cell proliferation. However, as senescent cells accumulate with age, the senescence-associated secretory phenotype (SASP) can disrupt tissues and contribute to age-related pathologies, including cancer. MTOR inhibition suppressed the secretion of inflammatory cytokines by senescent cells. Rapamycin reduced IL6 and other cytokine mRNA levels, but selectively suppressed translation of the membrane-bound cytokine IL1A. Reduced IL1A diminished NF-κB transcriptional activity, which controls much of the SASP; exogenous IL1A restored IL6 secretion to rapamycin-treated cells. Importantly, rapamycin suppressed the ability of senescent fibroblasts to stimulate prostate tumour growth in mice. Thus, rapamycin might ameliorate age-related pathologies, including late-life cancer, by suppressing senescence-associated inflammation. PMID:26147250

  11. Regulation of vascular smooth muscle cell autophagy by DNA nanotube-conjugated mTOR siRNA.

    PubMed

    You, Zaichun; Qian, Hang; Wang, Changzheng; He, Binfeng; Yan, Jiawei; Mao, Chengde; Wang, Guansong

    2015-10-01

    The efficient delivery of short interfering RNA (siRNA) is an enormous challenge in the field of gene therapy. Herein, we report a delivery nanosystem based on programmed DNA self-assembly mammalian target of rapamycin (mTOR) siRNA-loaded DNA nanotubes (DNA-NTs). We demonstrate that these siRNA-DNA-NTs can be effectively transfected into pulmonary arterial smooth muscle cells (PASMCs) via endocytosis; and that the loaded mTOR siRNA can induce obvious autophagy and inhibit cell growth under both normal and hypoxic conditions. Moreover, we found that mTOR siRNA can control the autophagy and proliferation of PASMCs under hypoxic condition, suggesting a potential therapeutic application for mTOR siRNA in diseases involving abnormal autophagy in PASMCs.

  12. [Dexamethasone affect on the expression of bcl-2 and mTOR genes in T-lymphocytes from healthy donors].

    PubMed

    Fatkhullina, A R; Abramov, S N; Skibo, Iu V; Abramova, Z I

    2014-01-01

    Synthetic glucocorticoids are able to activate apoptosis in the cells by regulating the transcription of the respective genes. Effect of dexamethasone on apoptosis is an established fact. However, its influence on another program of cell death autophagy, is currently unproven. Therefore, in this paper we have analyzed the influence of dexamethasone on the expression of bcl-2 and mTOR genes in T-lymphocytes from healthy donors. The results showed that dexamethasone reduced the expression of bcl-2 and mTOR genes. However, the nature of the effect of dexamethasone on mTOR and bcl-2 expression was different: the expression of bcl-2 gene in the long-term cultivation was maintained at the same reduced level, while the expression of mTOR was first reduced and then increased.

  13. mTOR inhibition activates overall protein degradation by the ubiquitin proteasome system as well as by autophagy.

    PubMed

    Zhao, Jinghui; Zhai, Bo; Gygi, Steven P; Goldberg, Alfred Lewis

    2015-12-29

    Growth factors and nutrients enhance protein synthesis and suppress overall protein degradation by activating the protein kinase mammalian target of rapamycin (mTOR). Conversely, nutrient or serum deprivation inhibits mTOR and stimulates protein breakdown by inducing autophagy, which provides the starved cells with amino acids for protein synthesis and energy production. However, it is unclear whether proteolysis by the ubiquitin proteasome system (UPS), which catalyzes most protein degradation in mammalian cells, also increases when mTOR activity decreases. Here we show that inhibiting mTOR with rapamycin or Torin1 rapidly increases the degradation of long-lived cell proteins, but not short-lived ones, by stimulating proteolysis by proteasomes, in addition to autophagy. This enhanced proteasomal degradation required protein ubiquitination, and within 30 min after mTOR inhibition, the cellular content of K48-linked ubiquitinated proteins increased without any change in proteasome content or activity. This rapid increase in UPS-mediated proteolysis continued for many hours and resulted primarily from inhibition of mTORC1 (not mTORC2), but did not require new protein synthesis or key mTOR targets: S6Ks, 4E-BPs, or Ulks. These findings do not support the recent report that mTORC1 inhibition reduces proteolysis by suppressing proteasome expression [Zhang Y, et al. (2014) Nature 513(7518):440-443]. Several growth-related proteins were identified that were ubiquitinated and degraded more rapidly after mTOR inhibition, including HMG-CoA synthase, whose enhanced degradation probably limits cholesterol biosynthesis upon insulin deficiency. Thus, mTOR inhibition coordinately activates the UPS and autophagy, which provide essential amino acids and, together with the enhanced ubiquitination of anabolic proteins, help slow growth. PMID:26669439

  14. Identification of a novel MTOR activator and discovery of a competing endogenous RNA regulating autophagy in vascular endothelial cells

    PubMed Central

    Ge, Di; Han, Lei; Huang, ShuYa; Peng, Nan; Wang, PengChong; Jiang, Zheng; Zhao, Jing; Su, Le; Zhang, ShangLi; Zhang, Yun; Kung, HsiangFu; Zhao, BaoXiang; Miao, JunYing

    2014-01-01

    MTOR, a central regulator of autophagy, is involved in cancer and cardiovascular and neurological diseases. Modulating the MTOR signaling balance could be of great significance for numerous diseases. No chemical activators of MTOR have been found, and the urgent challenge is to find novel MTOR downstream components. In previous studies, we found a chemical small molecule, 3-benzyl-5-((2-nitrophenoxy) methyl)–dihydrofuran-2(3H)-one (3BDO), that inhibited autophagy in human umbilical vein endothelial cells (HUVECs) and neuronal cells. Here, we found that 3BDO activated MTOR by targeting FKBP1A (FK506-binding protein 1A, 12 kDa). We next used 3BDO to detect novel factors downstream of the MTOR signaling pathway. Activation of MTOR by 3BDO increased the phosphorylation of TIA1 (TIA1 cytotoxic granule-associated RNA binding protein/T-cell-restricted intracellular antigen-1). Finally, we used gene microarray, RNA interference, RNA-ChIP assay, bioinformatics, luciferase reporter assay, and other assays and found that 3BDO greatly decreased the level of a long noncoding RNA (lncRNA) derived from the 3′ untranslated region (3′UTR) of TGFB2, known as FLJ11812. TIA1 was responsible for processing FLJ11812. Further experiments results showed that FLJ11812 could bind with MIR4459 targeting ATG13 (autophagy-related 13), and ATG13 protein level was decreased along with 3BDO-decreased FLJ11812 level. Here, we provide a new activator of MTOR, and our findings highlight the role of the lncRNA in autophagy. PMID:24879147

  15. Essential role of D1R in the regulation of mTOR complex1 signaling induced by cocaine.

    PubMed

    Sutton, Laurie P; Caron, Marc G

    2015-12-01

    The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that is involved in neuronal adaptions that underlie cocaine-induced sensitization and reward. mTOR exists in two functionally distinct multi-component complexes known as mTORC1 and mTORC2. In this study, we show that increased mTORC1 activity induced by cocaine is mediated by the dopamine D1 receptor (D1R). Specifically, cocaine treatment increased the phosphorylation on residues Thr2446 and Ser2481 but not on Ser2448 in the nucleus accumbens (NAc) and that this increase in phosphorylated mTOR levels was also apparent when complexed with its binding partner Raptor. Furthermore, the increase in phosphorylated mTOR levels, as well as phosphorylated 4E-BP1 and S6K, downstream targets of mTORC1 were blocked with SCH23390 treatment. Similar results were also observed in the dopamine-transporter knockout mice as the increase in phosphorylated mTOR Thr2446 and Ser2481 was blocked by SCH23390 but not with raclopride. To further validate D1R role in mTORC1 signaling, decrease in phosphorylated mTOR levels were observed in D1R knockout mice, whereas administration of SKF81297 elevated phosphorylated mTOR in the NAc. Lastly deletion of mTOR or Raptor in D1R expressing neurons reduced cocaine-induced locomotor activity. Together, our data supports a mechanism whereby mTORC1 signaling is activated by cocaine administration through the stimulation of D1R.

  16. Identification of a novel MTOR activator and discovery of a competing endogenous RNA regulating autophagy in vascular endothelial cells.

    PubMed

    Ge, Di; Han, Lei; Huang, ShuYa; Peng, Nan; Wang, PengChong; Jiang, Zheng; Zhao, Jing; Su, Le; Zhang, ShangLi; Zhang, Yun; Kung, HsiangFu; Zhao, BaoXiang; Miao, JunYing

    2014-06-01

    MTOR, a central regulator of autophagy, is involved in cancer and cardiovascular and neurological diseases. Modulating the MTOR signaling balance could be of great significance for numerous diseases. No chemical activators of MTOR have been found, and the urgent challenge is to find novel MTOR downstream components. In previous studies, we found a chemical small molecule, 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3H)-one (3BDO), that inhibited autophagy in human umbilical vein endothelial cells (HUVECs) and neuronal cells. Here, we found that 3BDO activated MTOR by targeting FKBP1A (FK506-binding protein 1A, 12 kDa). We next used 3BDO to detect novel factors downstream of the MTOR signaling pathway. Activation of MTOR by 3BDO increased the phosphorylation of TIA1 (TIA1 cytotoxic granule-associated RNA binding protein/T-cell-restricted intracellular antigen-1). Finally, we used gene microarray, RNA interference, RNA-ChIP assay, bioinformatics, luciferase reporter assay, and other assays and found that 3BDO greatly decreased the level of a long noncoding RNA (lncRNA) derived from the 3' untranslated region (3'UTR) of TGFB2, known as FLJ11812. TIA1 was responsible for processing FLJ11812. Further experiments results showed that FLJ11812 could bind with MIR4459 targeting ATG13 (autophagy-related 13), and ATG13 protein level was decreased along with 3BDO-decreased FLJ11812 level. Here, we provide a new activator of MTOR, and our findings highlight the role of the lncRNA in autophagy.

  17. The role of mTOR during cisplatin treatment in an in vitro and ex vivo model of cervical cancer.

    PubMed

    Leisching, G R; Loos, B; Botha, M H; Engelbrecht, A-M

    2015-09-01

    Cisplatin is used as a cytotoxic agent for the management of cervical cancer. However, the severity of the side-effects limits the use of this drug, particularly at high doses. Resistance to cisplatin is often attributed to a disruption in the normal apoptotic response via aberrant activation of pathways such as the mTOR pathway. Here we assess the role of mTOR and its effect on cell death sensitization and autophagy in response to a low concentration of cisplatin in cervical cancer cells. Additionally we measured the expression profile of mTOR in normal, low- and high-grade squamous intraepithelial (LSIL and HSIL) lesions and cancerous tissue. An in vitro model of cervical cancer was established using HeLa and CaSki cells. mTOR protein expression as well as autophagy-related proteins were evaluated through Western blotting. Inhibition of mTOR was achieved with the use of rapamycin and RNA silencing. A low concentration of cisplatin administered as a single agent induces autophagy, but not apoptosis. Cisplatin cytotoxicity was greatly enhanced in cancer cells when mTOR had been inhibited prior to cisplatin treatment which was likely due to autophagy being increased above cisplatin-induced levels, thereby inducing apoptosis. Cervical tissue samples revealed an increase in mTOR protein expression in LSIL and carcinoma tissue which suggests a change in autophagy control. Our data suggest that utilising a lower dose of cisplatin combined with mTOR inhibition is a viable treatment option and addresses the challenge of cisplatin dose-dependent toxicity, however future studies are required to confirm this in a clinical setting. PMID:26201060

  18. Involvement of PI3K/Akt/GSK-3β and mTOR in the antidepressant-like effect of atorvastatin in mice.

    PubMed

    Ludka, Fabiana Kalyne; Constantino, Leandra Celso; Dal-Cim, Tharine; Binder, Luisa Bandeira; Zomkowski, Andréa; Rodrigues, Ana Lúcia S; Tasca, Carla Inês

    2016-11-01

    Atorvastatin is a cholesterol-lowering statin that has been shown to exert several pleiotropic effects in the nervous system as a neuroprotective and antidepressant-like agent. Antidepressant-like effect of atorvastatin in mice is mediated by glutamatergic and serotoninergic receptors, although the precise intracellular signaling pathways involved are unknown. PI3K/Akt/GSK-3β/mTOR signaling pathway has been associated to neurobiology of depression and seems to be modulated by some pharmacological antidepressant strategies. The present study investigated the participation of the PI3K/Akt/GSK-3β/mTOR signaling pathway in the antidepressant-like effect of an acute atorvastatin treatment in mice. Atorvastatin sub-effective (0.01 mg/kg) or effective (0.1 mg/kg) doses in the tail suspension test (TST) was administered orally alone or in combination with PI3K, GSK-3β or mTOR inhibitors. The administration of PI3K inhibitor, LY294002 (10 nmol/site, i.c.v) completely prevented the antidepressant-like effect of atorvastatin (0.1 mg/kg, p.o.). The participation of GSK-3β in the antidepressant-like effect of atorvastatin was demonstrated by co-administration of a sub-effective dose of atorvastatin (0.01 mg/kg, p.o.) with AR-A014418 (0.01 μg/site, i.c.v., a selective GSK-3β inhibitor) or with lithium chloride (10 mg/kg, p.o., a non-selective GSK-3β inhibitor). The mTOR inhibitor, rapamycin (0.2 nmol/site, i.c.v.) was also able to prevent atorvastatin (0.1 mg/kg, p.o.) antidepressant-like effect. These behavioral findings were supported by neurochemical observations, as atorvastatin treatment increased the immunocontent of the phosphorylated isoforms of Akt, GSK-3β and mTOR in the hippocampus of mice. Taken together, our results suggest an involvement of the PI3K/Akt/GSK-3β/mTOR signaling pathway in the antidepressant-like effect of atorvastatin in mice.

  19. Involvement of PI3K/Akt/GSK-3β and mTOR in the antidepressant-like effect of atorvastatin in mice.

    PubMed

    Ludka, Fabiana Kalyne; Constantino, Leandra Celso; Dal-Cim, Tharine; Binder, Luisa Bandeira; Zomkowski, Andréa; Rodrigues, Ana Lúcia S; Tasca, Carla Inês

    2016-11-01

    Atorvastatin is a cholesterol-lowering statin that has been shown to exert several pleiotropic effects in the nervous system as a neuroprotective and antidepressant-like agent. Antidepressant-like effect of atorvastatin in mice is mediated by glutamatergic and serotoninergic receptors, although the precise intracellular signaling pathways involved are unknown. PI3K/Akt/GSK-3β/mTOR signaling pathway has been associated to neurobiology of depression and seems to be modulated by some pharmacological antidepressant strategies. The present study investigated the participation of the PI3K/Akt/GSK-3β/mTOR signaling pathway in the antidepressant-like effect of an acute atorvastatin treatment in mice. Atorvastatin sub-effective (0.01 mg/kg) or effective (0.1 mg/kg) doses in the tail suspension test (TST) was administered orally alone or in combination with PI3K, GSK-3β or mTOR inhibitors. The administration of PI3K inhibitor, LY294002 (10 nmol/site, i.c.v) completely prevented the antidepressant-like effect of atorvastatin (0.1 mg/kg, p.o.). The participation of GSK-3β in the antidepressant-like effect of atorvastatin was demonstrated by co-administration of a sub-effective dose of atorvastatin (0.01 mg/kg, p.o.) with AR-A014418 (0.01 μg/site, i.c.v., a selective GSK-3β inhibitor) or with lithium chloride (10 mg/kg, p.o., a non-selective GSK-3β inhibitor). The mTOR inhibitor, rapamycin (0.2 nmol/site, i.c.v.) was also able to prevent atorvastatin (0.1 mg/kg, p.o.) antidepressant-like effect. These behavioral findings were supported by neurochemical observations, as atorvastatin treatment increased the immunocontent of the phosphorylated isoforms of Akt, GSK-3β and mTOR in the hippocampus of mice. Taken together, our results suggest an involvement of the PI3K/Akt/GSK-3β/mTOR signaling pathway in the antidepressant-like effect of atorvastatin in mice. PMID:27468164

  20. A pilot study of JI-101, an inhibitor of VEGFR-2, PDGFR-β, and EphB4 receptors, in combination with everolimus and as a single agent in an ovarian cancer expansion cohort.

    PubMed

    Werner, Theresa L; Wade, Mark L; Agarwal, Neeraj; Boucher, Kenneth; Patel, Jesal; Luebke, Aaron; Sharma, Sunil

    2015-12-01

    JI-101 is an oral multi-kinase inhibitor that targets vascular endothelial growth factor receptor type 2 (VEGFR-2), platelet derived growth factor receptor β (PDGFR-β), and ephrin type-B receptor 4 (EphB4). None of the currently approved angiogenesis inhibitors have been reported to inhibit EphB4, and therefore, JI-101 has a novel mechanism of action. We conducted a pilot trial to assess the pharmacokinetics (PK), tolerability, and efficacy of JI-101 in combination with everolimus in advanced cancers, and pharmacodynamics (PD), tolerability, and efficacy of JI-101 in ovarian cancer. This was the first clinical study assessing anti-tumor activity of JI-101 in a combinatorial regimen. In the PK cohort, four patients received single agent 10 mg everolimus on day 1, 10 mg everolimus and 200 mg JI-101 combination on day 8, and single agent 200 mg JI-101 on day 15. In the PD cohort, eleven patients received single agent JI-101 at 200 mg twice daily for 28 day treatment cycles. JI-101 was well tolerated as a single agent and in combination with everolimus. No serious adverse events were observed. Common adverse events were hypertension, nausea, and abdominal pain. JI-101 increased exposure of everolimus by approximately 22%, suggestive of drug-drug interaction. The majority of patients had stable disease at their first set of restaging scans (two months), although no patients demonstrated a response to the drug per RECIST criteria. The novel mechanism of action of JI-101 is promising in ovarian cancer treatment and further prospective studies of this agent may be pursued in a less refractory patient population or in combination with cytotoxic chemotherapy.

  1. Caloric restriction protects against electrical kindling of the amygdala by inhibiting the mTOR signaling pathway.

    PubMed

    Phillips-Farfán, Bryan V; Rubio Osornio, María Del Carmen; Custodio Ramírez, Verónica; Paz Tres, Carlos; Carvajal Aguilera, Karla G

    2015-01-01

    Caloric restriction (CR) has been shown to possess antiepileptic properties; however its mechanism of action is poorly understood. CR might inhibit the activity of the mammalian or mechanistic target of rapamycin (mTOR) signaling cascade, which seems to participate crucially in the generation of epilepsy. Thus, we investigated the effect of CR on the mTOR pathway and whether CR modified epilepsy generation due to electrical amygdala kindling. The former was studied by analyzing the phosphorylation of adenosine monophosphate-activated protein kinase, protein kinase B and the ribosomal protein S6. The mTOR cascade is regulated by energy and by insulin levels, both of which may be changed by CR; thus we investigated if CR altered the levels of energy substrates in the blood or the level of insulin in plasma. Finally, we studied if CR modified the expression of genes that encode proteins participating in the mTOR pathway. CR increased the after-discharge threshold and tended to reduce the after-discharge duration, indicating an anti-convulsive action. CR diminished the phosphorylation of protein kinase B and ribosomal protein S6, suggesting an inhibition of the mTOR cascade. However, CR did not change glucose, β-hydroxybutyrate or insulin levels; thus the effects of CR were independent from them. Interestingly, CR also did not modify the expression of any investigated gene. The results suggest that the anti-epileptic effect of CR may be partly due to inhibition of the mTOR pathway.

  2. Nuclear reprogramming of luminal-like breast cancer cells generates Sox2-overexpressing cancer stem-like cellular states harboring transcriptional activation of the mTOR pathway.

    PubMed

    Corominas-Faja, Bruna; Cufí, Sílvia; Oliveras-Ferraros, Cristina; Cuyàs, Elisabet; López-Bonet, Eugeni; Lupu, Ruth; Alarcón, Tomás; Vellon, Luciano; Iglesias, Juan Manuel; Leis, Olatz; Martín, Ángel G; Vazquez-Martin, Alejandro; Menendez, Javier A

    2013-09-15

    . Consistent with the downregulation of AMPK expression, immunoblotting procedures confirmed upregulation of p70S6K and increased phosphorylation of mTOR in Sox2-overexpressing CSC-like cell populations. Using an in vitro model of the de novo generation of CSC-like states through the nuclear reprogramming of an established breast cancer cell line, we reveal that the transcriptional suppression of mTOR repressors is an intrinsic process occurring during the acquisition of CSC-like properties by differentiated populations of luminal-like breast cancer cells. This approach may provide a new path for obtaining information about preventing the appearance of CSCs through the modulation of the AMPK/mTOR pathway.

  3. Nuclear reprogramming of luminal-like breast cancer cells generates Sox2-overexpressing cancer stem-like cellular states harboring transcriptional activation of the mTOR pathway

    PubMed Central

    Corominas-Faja, Bruna; Cufí, Sílvia; Oliveras-Ferraros, Cristina; Cuyàs, Elisabet; López-Bonet, Eugeni; Lupu, Ruth; Alarcón, Tomás; Vellon, Luciano; Iglesias, Juan Manuel; Leis, Olatz; Martín, Ángel G; Vazquez-Martin, Alejandro; Menendez, Javier A

    2013-01-01

    cells. Consistent with the downregulation of AMPK expression, immunoblotting procedures confirmed upregulation of p70S6K and increased phosphorylation of mTOR in Sox2-overexpressing CSC-like cell populations. Using an in vitro model of the de novo generation of CSC-like states through the nuclear reprogramming of an established breast cancer cell line, we reveal that the transcriptional suppression of mTOR repressors is an intrinsic process occurring during the acquisition of CSC-like properties by differentiated populations of luminal-like breast cancer cells. This approach may provide a new path for obtaining information about preventing the appearance of CSCs through the modulation of the AMPK/mTOR pathway. PMID:23974095

  4. Infectious tolerance via the consumption of essential amino acids and mTOR signaling.

    PubMed

    Cobbold, Stephen P; Adams, Elizabeth; Farquhar, Claire A; Nolan, Kathleen F; Howie, Duncan; Lui, Kathy O; Fairchild, Paul J; Mellor, Andrew L; Ron, David; Waldmann, Herman

    2009-07-21

    Infectious tolerance describes the process of CD4(+) regulatory T cells (Tregs) converting naïve T cells to become additional Tregs. We show that antigen-specific Tregs induce, within skin grafts and dendritic cells, the expression of enzymes that consume at least 5 different essential amino acids (EAAs). T cells fail to proliferate in response to antigen when any 1, or more, of these EAAs are limiting, which is associated with a reduced mammalian target of rapamycin (mTOR) signaling. Inhibition of the mTOR pathway by limiting EAAs, or by specific inhibitors, induces the Treg-specific transcription factor forkhead box P3, which depends on both T cell receptor activation and synergy with TGF-beta. PMID:19567830

  5. BMAL1-dependent regulation of the mTOR signaling pathway delays aging.

    PubMed

    Khapre, Rohini V; Kondratova, Anna A; Patel, Sonal; Dubrovsky, Yuliya; Wrobel, Michelle; Antoch, Marina P; Kondratov, Roman V

    2014-01-01

    The circadian clock, an internal time-keeping system, has been linked with control of aging, but molecular mechanisms of regulation are not known. BMAL1 is a transcriptional factor and core component of the circadian clock; BMAL1 deficiency is associated with premature aging and reduced lifespan. Here we report that activity of mammalian Target of Rapamycin Complex 1 (mTORC1) is increased upon BMAL1 deficiency both in vivo and in cell culture. Increased mTOR signaling is associated with accelerated aging; in accordance with that, treatment with the mTORC1 inhibitor rapamycin increased lifespan of Bmal1-/- mice by 50%. Our data suggest that BMAL1 is a negative regulator of mTORC1 signaling. We propose that the circadian clock controls the activity of the mTOR pathway through BMAL1-dependent mechanisms and this regulation is important for control of aging and metabolism.

  6. Regulation of mTOR activity in Snell dwarf and GH receptor gene-disrupted mice.

    PubMed

    Dominick, Graham; Berryman, Darlene E; List, Edward O; Kopchick, John J; Li, Xinna; Miller, Richard A; Garcia, Gonzalo G

    2015-02-01

    The involvement of mammalian target of rapamycin (mTOR) in lifespan control in invertebrates, calorie-restricted rodents, and extension of mouse lifespan by rapamycin have prompted speculation that diminished mTOR function may contribute to mammalian longevity in several settings. We show here that mTOR complex-1 (mTORC1) activity is indeed lower in liver, muscle, heart, and kidney tissue of Snell dwarf and global GH receptor (GHR) gene-disrupted mice (GHR-/-), consistent with previous studies. Surprisingly, activity of mTORC2 is higher in fasted Snell and GHR-/- than in littermate controls in all 4 tissues tested. Resupply of food enhanced mTORC1 activity in both controls and long-lived mutant mice but diminished mTORC2 activity only in the long-lived mice. Mice in which GHR has been disrupted only in the liver do not show extended lifespan and also fail to show the decline in mTORC1 and increase in mTORC2 seen in mice with global loss of GHR. The data suggest that the antiaging effects in the Snell dwarf and GHR-/- mice are accompanied by both a decline in mTORC1 in multiple organs and an increase in fasting levels of mTORC2. Neither the lifespan nor mTOR effects appear to be mediated by direct GH effects on liver or by the decline in plasma IGF-I, a shared trait in both global and liver-specific GHR-/- mice. Our data suggest that a more complex pattern of hormonal effects and intertissue interactions may be responsible for regulating both lifespan and mTORC2 function in these mouse models of delayed aging.

  7. Stoichiometry and assembly of mTOR complexes revealed by single-molecule pulldown.

    PubMed

    Jain, Ankur; Arauz, Edwin; Aggarwal, Vasudha; Ikon, Nikita; Chen, Jie; Ha, Taekjip

    2014-12-16

    The mammalian target of rapamycin (mTOR) kinase is a master regulator of cellular, developmental, and metabolic processes. Deregulation of mTOR signaling is implicated in numerous human diseases including cancer and diabetes. mTOR functions as part of either of the two multisubunit complexes, mTORC1 and mTORC2, but molecular details about the assembly and oligomerization of mTORCs are currently lacking. We use the single-molecule pulldown (SiMPull) assay that combines principles of conventional pulldown assays with single-molecule fluorescence microscopy to investigate the stoichiometry and assembly of mTORCs. After validating our approach with mTORC1, confirming a dimeric assembly as previously reported, we show that all major components of mTORC2 exist in two copies per complex, indicating that mTORC2 assembles as a homodimer. Interestingly, each mTORC component, when free from the complexes, is present as a monomer and no single subunit serves as the dimerizing component. Instead, our data suggest that dimerization of mTORCs is the result of multiple subunits forming a composite surface. SiMPull also allowed us to distinguish complex disassembly from stoichiometry changes. Physiological conditions that abrogate mTOR signaling such as nutrient deprivation or energy stress did not alter the stoichiometry of mTORCs. On the other hand, rapamycin treatment leads to transient appearance of monomeric mTORC1 before complete disruption of the mTOR-raptor interaction, whereas mTORC2 stoichiometry is unaffected. These insights into assembly of mTORCs may guide future mechanistic studies and exploration of therapeutic potential.

  8. Azithromycin suppresses CD4+ T-cell activation by direct modulation of mTOR activity

    PubMed Central

    Ratzinger, F.; Haslacher, H.; Poeppl, W.; Hoermann, G.; Kovarik, J. J.; Jutz, S.; Steinberger, P.; Burgmann, H.; Pickl, W. F.; Schmetterer, K. G.

    2014-01-01

    Advanced macrolides, such as azithromycin (AZM) or clarithromycin (CLM), are antibiotics with immunomodulatory properties. Here we have sought to evaluate their in vitro influence on the activation of CD4+ T-cells. Isolated CD4+ T-cells were stimulated with agonistic anti-CD3/anti-CD28 monoclonal antibodies in the presence of 0.6 mg/L, 2.5 mg/L, 10 mg/L or 40 mg/L AZM or CLM. Cell proliferation, cytokine level in supernatants and cell viability was assessed. Intracellular signaling pathways were evaluated using reporter cell lines, FACS analysis, immunoblotting and in vitro kinase assays. AZM inhibited cell proliferation rate and cytokine secretion of CD4+ T-cells in a dose-dependent manner. Similarly, high concentrations of CLM (40 mg/L) also suppressed these T-cell functions. Analysis of molecular signaling pathways revealed that exposure to AZM reduced the phosphorylation of the S6 ribosomal protein, a downstream target of mTOR. This effect was also observed at 40 mg/L CLM. In vitro kinase studies using recombinant mTOR showed that AZM inhibited mTOR activity. In contrast to rapamycin, this inhibition was independent of FKBP12. We show for the first time that AZM and to a lesser extent CLM act as immunosuppressive agents on CD4+ T-cells by inhibiting mTOR activity. Our results might have implications for the clinical use of macrolides. PMID:25500904

  9. Regulation of mTOR activity in Snell dwarf and GH receptor gene-disrupted mice.

    PubMed

    Dominick, Graham; Berryman, Darlene E; List, Edward O; Kopchick, John J; Li, Xinna; Miller, Richard A; Garcia, Gonzalo G

    2015-02-01

    The involvement of mammalian target of rapamycin (mTOR) in lifespan control in invertebrates, calorie-restricted rodents, and extension of mouse lifespan by rapamycin have prompted speculation that diminished mTOR function may contribute to mammalian longevity in several settings. We show here that mTOR complex-1 (mTORC1) activity is indeed lower in liver, muscle, heart, and kidney tissue of Snell dwarf and global GH receptor (GHR) gene-disrupted mice (GHR-/-), consistent with previous studies. Surprisingly, activity of mTORC2 is higher in fasted Snell and GHR-/- than in littermate controls in all 4 tissues tested. Resupply of food enhanced mTORC1 activity in both controls and long-lived mutant mice but diminished mTORC2 activity only in the long-lived mice. Mice in which GHR has been disrupted only in the liver do not show extended lifespan and also fail to show the decline in mTORC1 and increase in mTORC2 seen in mice with global loss of GHR. The data suggest that the antiaging effects in the Snell dwarf and GHR-/- mice are accompanied by both a decline in mTORC1 in multiple organs and an increase in fasting levels of mTORC2. Neither the lifespan nor mTOR effects appear to be mediated by direct GH effects on liver or by the decline in plasma IGF-I, a shared trait in both global and liver-specific GHR-/- mice. Our data suggest that a more complex pattern of hormonal effects and intertissue interactions may be responsible for regulating both lifespan and mTORC2 function in these mouse models of delayed aging. PMID:25456069

  10. Repression of protein translation and mTOR signaling by proteasome inhibitor in colon cancer cells

    SciTech Connect

    Wu, William Ka Kei; Volta, Viviana; Cho, Chi Hin; Wu, Ya Chun; Li, Hai Tao; Yu, Le; Li, Zhi Jie; Sung, Joseph Jao Yiu

    2009-09-04

    Protein homeostasis relies on a balance between protein synthesis and protein degradation. The ubiquitin-proteasome system is a major catabolic pathway for protein degradation. In this respect, proteasome inhibition has been used therapeutically for the treatment of cancer. Whether inhibition of protein degradation by proteasome inhibitor can repress protein translation via a negative feedback mechanism, however, is unknown. In this study, proteasome inhibitor MG-132 lowered the proliferation of colon cancer cells HT-29 and SW1116. In this connection, MG-132 reduced the phosphorylation of mammalian target of rapamycin (mTOR) at Ser2448 and Ser2481 and the phosphorylation of its downstream targets 4E-BP1 and p70/p85 S6 kinases. Further analysis revealed that MG-132 inhibited protein translation as evidenced by the reductions of {sup 35}S-methionine incorporation and polysomes/80S ratio. Knockdown of raptor, a structural component of mTOR complex 1, mimicked the anti-proliferative effect of MG-132. To conclude, we demonstrate that the inhibition of protein degradation by proteasome inhibitor represses mTOR signaling and protein translation in colon cancer cells.

  11. SMN regulates axonal local translation via miR-183/mTOR pathway

    PubMed Central

    Kye, Min Jeong; Niederst, Emily D.; Wertz, Mary H.; Gonçalves, Inês do Carmo G.; Akten, Bikem; Dover, Katarzyna Z.; Peters, Miriam; Riessland, Markus; Neveu, Pierre; Wirth, Brunhilde; Kosik, Kenneth S.; Sardi, S. Pablo; Monani, Umrao R.; Passini, Marco A.; Sahin, Mustafa

    2014-01-01

    Reduced expression of SMN protein causes spinal muscular atrophy (SMA), a neurodegenerative disorder leading to motor neuron dysfunction and loss. However, the molecular mechanisms by which SMN regulates neuronal dysfunction are not fully understood. Here, we report that reduced SMN protein level alters miRNA expression and distribution in neurons. In particular, miR-183 levels are increased in neurites of SMN-deficient neurons. We demonstrate that miR-183 regulates translation of mTor via direct binding to its 3′ UTR. Interestingly, local axonal translation of mTor is reduced in SMN-deficient neurons, and this can be recovered by miR-183 inhibition. Finally, inhibition of miR-183 expression in the spinal cord of an SMA mouse model prolongs survival and improves motor function of Smn-mutant mice. Together, these observations suggest that axonal miRNAs and the mTOR pathway are previously unidentified molecular mechanisms contributing to SMA pathology. PMID:25055867

  12. mTOR Mediates IL-23 Induction of Neutrophil IL-17 and IL-22 Production.

    PubMed

    Chen, Feidi; Cao, Anthony; Yao, Suxia; Evans-Marin, Heather L; Liu, Han; Wu, Wei; Carlsen, Eric D; Dann, Sara M; Soong, Lynn; Sun, Jiaren; Zhao, Qihong; Cong, Yingzi

    2016-05-15

    It has been shown recently that neutrophils are able to produce IL-22 and IL-17, which differentially regulate the pathogenesis of inflammatory bowel disease. However, it is still largely unknown how the neutrophil production of IL-22 and IL-17 is regulated, and their role in the pathogenesis of inflammatory bowel disease. In this study, we found that IL-23 promoted neutrophil production of IL-17 and IL-22. IL-23 stimulated the neutrophil expression of IL-23R as well as rorc and ahr. Retinoid acid receptor-related orphan receptor γ t and aryl-hydrocarbon receptor differentially regulated IL-23 induction of neutrophil IL-17 and IL-22. In addition, IL-23 induced the activation of mTOR in neutrophils. Blockade of the mTOR pathway inhibited IL-23-induced expression of rorc and ahr, as well as IL-17 and IL-22 production. By using a microbiota Ag-specific T cell-mediated colitis model, we demonstrated that depletion of neutrophils, as well as blockade of IL-22, resulted in a significant increase in the severity of colitis, thereby indicating a protective role of neutrophils and IL-22 in chronic colitis. Collectively, our data revealed that neutrophils negatively regulate microbiota Ag-specific T cell induction of colitis, and IL-23 induces neutrophil production of IL-22 and IL-17 through induction of rorc and ahr, which is mediated by the mTOR pathway.

  13. Reciprocal regulation of cilia and autophagy via the MTOR and proteasome pathways.

    PubMed

    Wang, Shixuan; Livingston, Man J; Su, Yunchao; Dong, Zheng

    2015-04-01

    Primary cilium is an organelle that plays significant roles in a number of cellular functions ranging from cell mechanosensation, proliferation, and differentiation to apoptosis. Autophagy is an evolutionarily conserved cellular function in biology and indispensable for cellular homeostasis. Both cilia and autophagy have been linked to different types of genetic and acquired human diseases. Their interaction has been suggested very recently, but the underlying mechanisms are still not fully understood. We examined autophagy in cells with suppressed cilia and measured cilium length in autophagy-activated or -suppressed cells. It was found that autophagy was repressed in cells with short cilia. Further investigation showed that MTOR activation was enhanced in cilia-suppressed cells and the MTOR inhibitor rapamycin could largely reverse autophagy suppression. In human kidney proximal tubular cells (HK2), autophagy induction was associated with cilium elongation. Conversely, autophagy inhibition by 3-methyladenine (3-MA) and chloroquine (CQ) as well as bafilomycin A1 (Baf) led to short cilia. Cilia were also shorter in cultured atg5-knockout (KO) cells and in atg7-KO kidney proximal tubular cells in mice. MG132, an inhibitor of the proteasome, could significantly restore cilium length in atg5-KO cells, being concomitant with the proteasome activity. Together, the results suggest that cilia and autophagy regulate reciprocally through the MTOR signaling pathway and ubiquitin-proteasome system.

  14. IL-12 is required for mTOR regulation of memory CTLs during viral infection

    PubMed Central

    Garcia, Karla; Sun, Zhifeng; Mattson, Elliot; Li, Lei; Smyth, Kendra; Xiao, Zhengguo

    2014-01-01

    The induction of functional memory CTLs is a major goal of vaccination against intracellular pathogens. IL-12 is critical for the generation of memory CTLs, and inhibition of mTOR by rapamycin can effectively enhance the memory CTL response. Yet, the role of IL-12 in mTOR’s regulation of memory CTL is unknown. Here, we hypothesized that the immunostimulatory effects of mTOR on memory CTLs requires IL-12 signaling. Our results revealed that rapamycin increased the generation of memory CTLs in vaccinia virus infection, and this enhancement was dependent upon the IL-12 signal. Furthermore, IL-12 receptor deficiency diminished the secondary expansion of rapamycin-regulated memory, and resultant secondary memory CTLs were abolished. Rapamycin enhanced IL-12 signaling by up regulating IL-12 receptor β2 expression and STAT4 phosphorylation in CTLs during early infection. In addition, rapamycin continually suppressed T-bet expression in both WT and IL-12 receptor knockout CTLs. These results indicate an essential role for IL-12 in the regulation of memory CTLs by mTOR, and highlight the importance of considering the interplay between cytokines and adjuvants during vaccine design. PMID:24898389

  15. Baicalein inhibits lipid accumulation by regulating early adipogenesis and m-TOR signaling.

    PubMed

    Seo, Min-Jung; Choi, Hyeon-Son; Jeon, Hui-Jeon; Woo, Mi-Seon; Lee, Boo-Yong

    2014-05-01

    Baicalein is a type of flavonoid that originates from Scutellaria baicalensis. In this study, we examined how baicalein inhibits lipid accumulation during adipogenesis in 3T3-L1 cells. Our data show that baicalein inhibited lipid accumulation during adipogenesis in a dose-dependent manner. Baicalein inhibition was limited to the early adipogenic stage. Cell cycle analysis showed that baicalein induced cell cycle arrest in the G0/G1 phase through cyclin downregulation. In addition, baicalein suppressed the mRNA expression of early adipogenic factors leading to downregulation of late adipogenic factors at mRNA and protein levels. Inhibition of adipogenic factors by baicalein was correlated with downregulation of lipid synthetic enzymes. Additionally, baicalein negatively regulated the m-TOR signaling pathway involved in lipid accumulation during adipogenesis, thus inhibiting phosphorylation of m-TOR and p70S6K. In a zebrafish study, baicalein significantly reduced lipid accumulation in Nile Red staining. Consistent with a report using cell lines, mRNA expression of adipogenic factors was decreased in a dose-dependent manner by baicalein. This result reflects a reduction in total triglyceride levels based on a triglyceride assay. Our data suggest that baicalein inhibits lipid accumulation by controlling the cell cycle and m-TOR signaling in 3T3-L1 cells, and its anti-adipogenic effect was found in a zebrafish model.

  16. A liaison between mTOR signaling, ribosome biogenesis and cancer☆

    PubMed Central

    Gentilella, Antonio; Kozma, Sara C.; Thomas, George

    2016-01-01

    The ability to translate genetic information into functional proteins is considered a landmark in evolution. Ribosomes have evolved to take on this responsibility and, although there are some differences in their molecular make-up, both prokaryotes and eukaryotes share a common structural architecture and similar underlying mechanisms of protein synthesis. Understanding ribosome function and biogenesis has been the focus of extensive research since the early days of their discovery. In the last decade however, new and unexpected roles have emerged that place deregulated ribosome biogenesis and protein synthesis at the crossroads of pathological settings, particularly cancer, revealing a set of novel cellular checkpoints. Moreover, it is also becoming evident that mTOR signaling, which regulates an array of anabolic processes, including ribosome biogenesis, is often exploited by cancer cells to sustain proliferation through the upregulation of global protein synthesis. The use of pharmacological agents that interfere with ribosome biogenesis and mTOR signaling has proven to be an effective strategy to control cancer development clinically. Here we discuss the most recent findings concerning the underlying mechanisms by which mTOR signaling controls ribosome production and the potential impact of ribosome bio-genesis in tumor development. This article is part of a Special Issue entitled: Translation and Cancer. PMID:25735853

  17. A liaison between mTOR signaling, ribosome biogenesis and cancer.

    PubMed

    Gentilella, Antonio; Kozma, Sara C; Thomas, George

    2015-07-01

    The ability to translate genetic information into functional proteins is considered a landmark in evolution. Ribosomes have evolved to take on this responsibility and, although there are some differences in their molecular make-up, both prokaryotes and eukaryotes share a common structural architecture and similar underlying mechanisms of protein synthesis. Understanding ribosome function and biogenesis has been the focus of extensive research since the early days of their discovery. In the last decade however, new and unexpected roles have emerged that place deregulated ribosome biogenesis and protein synthesis at the crossroads of pathological settings, particularly cancer, revealing a set of novel cellular checkpoints. Moreover, it is also becoming evident that mTOR signaling, which regulates an array of anabolic processes, including ribosome biogenesis, is often exploited by cancer cells to sustain proliferation through the upregulation of global protein synthesis. The use of pharmacological agents that interfere with ribosome biogenesis and mTOR signaling has proven to be an effective strategy to control cancer development clinically. Here we discuss the most recent findings concerning the underlying mechanisms by which mTOR signaling controls ribosome production and the potential impact of ribosome biogenesis in tumor development. This article is part of a Special Issue entitled: Translation and Cancer.

  18. Effects of Fluoride on the Expression of Beclin1 and mTOR in Ameloblasts.

    PubMed

    Lei, Shuang; Zhang, Ying; Zhang, Kaiqiang; Li, Jian; Liu, Lu

    2015-01-01

    Exposure to high levels of fluoride (F-) can result in dental fluorosis in different individuals, but the mechanism of dental fluorosis remains unclear. Autophagy is a highly conserved intracellular digestion process that degrades damaged organelles and protein aggregates. This study examined the effect of sodium fluoride (NaF) on the expression of Beclin1 and mTOR to elucidate the development mechanisms of dental fluorosis. HAT-7 cells were incubated with various concentrations of NaF, and autophagic vacuoles were studied by transmission electron microscopy. At both mRNA and protein level, expression of Beclin1, which is required for autophagosome formation and decreases the expression of mTOR, an autophagy-related complex, was increased at 1.2 mmol/l NaF compared to baseline (0 mmol/l NaF). Additionally, immunohistochemical analysis was performed on paraffin-embedded rat incisor sections to identify the expression of Beclin1 and mTOR proteins in vitro. Highly significant differences were detected compared to controls. In summary, our results demonstrate unequivocally that excessive amounts of fluoride cause autophagy of HAT-7 cells, indicating that autophagy is involved in dental fluorosis. PMID:26562167

  19. A liaison between mTOR signaling, ribosome biogenesis and cancer.

    PubMed

    Gentilella, Antonio; Kozma, Sara C; Thomas, George

    2015-07-01

    The ability to translate genetic information into functional proteins is considered a landmark in evolution. Ribosomes have evolved to take on this responsibility and, although there are some differences in their molecular make-up, both prokaryotes and eukaryotes share a common structural architecture and similar underlying mechanisms of protein synthesis. Understanding ribosome function and biogenesis has been the focus of extensive research since the early days of their discovery. In the last decade however, new and unexpected roles have emerged that place deregulated ribosome biogenesis and protein synthesis at the crossroads of pathological settings, particularly cancer, revealing a set of novel cellular checkpoints. Moreover, it is also becoming evident that mTOR signaling, which regulates an array of anabolic processes, including ribosome biogenesis, is often exploited by cancer cells to sustain proliferation through the upregulation of global protein synthesis. The use of pharmacological agents that interfere with ribosome biogenesis and mTOR signaling has proven to be an effective strategy to control cancer development clinically. Here we discuss the most recent findings concerning the underlying mechanisms by which mTOR signaling controls ribosome production and the potential impact of ribosome biogenesis in tumor development. This article is part of a Special Issue entitled: Translation and Cancer. PMID:25735853

  20. mTOR is critical for intestinal T-cell homeostasis and resistance to Citrobacter rodentium

    PubMed Central

    Lin, Xingguang; Yang, Jialong; Wang, Jinli; Huang, Hongxiang; Wang, Hong-Xia; Chen, Pengcheng; Wang, Shang; Pan, Yun; Qiu, Yu-Rong; Taylor, Gregory A.; Vallance, Bruce A.; Gao, Jimin; Zhong, Xiao-Ping

    2016-01-01

    T-cells play an important role in promoting mucosal immunity against pathogens, but the mechanistic basis for their homeostasis in the intestine is still poorly understood. We report here that T-cell-specific deletion of mTOR results in dramatically decreased CD4 and CD8 T-cell numbers in the lamina propria of both small and large intestines under both steady-state and inflammatory conditions. These defects result in defective host resistance against a murine enteropathogen, Citrobacter rodentium, leading to the death of the animals. We further demonstrated that mTOR deficiency reduces the generation of gut-homing effector T-cells in both mesenteric lymph nodes and Peyer’s patches without obviously affecting expression of gut-homing molecules on those effector T-cells. Using mice with T-cell-specific ablation of Raptor/mTORC1 or Rictor/mTORC2, we revealed that both mTORC1 and, to a lesser extent, mTORC2 contribute to both CD4 and CD8 T-cell accumulation in the gastrointestinal (GI) tract. Additionally, mTORC1 but not mTORC2 plays an important role regulating the proliferative renewal of both CD4 and CD8 T-cells in the intestines. Our data thus reveal that mTOR is crucial for T-cell accumulation in the GI tract and for establishing local adaptive immunity against pathogens. PMID:27731345

  1. FK866-induced NAMPT inhibition activates AMPK and downregulates mTOR signaling in hepatocarcinoma cells

    SciTech Connect

    Schuster, Susanne; Penke, Melanie; Gorski, Theresa; Gebhardt, Rolf; Weiss, Thomas S.; Kiess, Wieland; Garten, Antje

    2015-03-06

    Background: Nicotinamide phosphoribosyltransferase (NAMPT) is the key enzyme of the NAD salvage pathway starting from nicotinamide. Cancer cells have an increased demand for NAD due to their high proliferation and DNA repair rate. Consequently, NAMPT is considered as a putative target for anti-cancer therapies. There is evidence that AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) become dysregulated during the development of hepatocellular carcinoma (HCC). Here, we investigated the effects of NAMPT inhibition by its specific inhibitor FK866 on the viability of hepatocarcinoma cells and analyzed the effects of FK866 on the nutrient sensor AMPK and mTOR complex1 (mTORC1) signaling. Results: FK866 markedly decreased NAMPT activity and NAD content in hepatocarcinoma cells (Huh7 cells, Hep3B cells) and led to delayed ATP reduction which was associated with increased cell death. These effects could be abrogated by administration of nicotinamide mononucleotide (NMN), the enzyme product of NAMPT. Our results demonstrated a dysregulation of the AMPK/mTOR pathway in hepatocarcinoma cells compared to non-cancerous hepatocytes with a higher expression of mTOR and a lower AMPKα activation in hepatocarcinoma cells. We found that NAMPT inhibition by FK866 significantly activated AMPKα and inhibited the activation of mTOR and its downstream targets p70S6 kinase and 4E-BP1 in hepatocarcinoma cells. Non-cancerous hepatocytes were less sensitive to FK866 and did not show changes in AMPK/mTOR signaling after FK866 treatment. Conclusion: Taken together, these findings reveal an important role of the NAMPT-mediated NAD salvage pathway in the energy homeostasis of hepatocarcinoma cells and suggest NAMPT inhibition as a potential treatment option for HCC. - Highlights: • FK866 increases cell death in p53-deficient hepatocarcinoma cells. • AMPK/mTOR signaling is dysregulated in hepatocarcinoma cells. • FK866-induced NAMPT inhibition activates AMPK

  2. Tuberous sclerosis complex, mTOR, and the kidney: report of an NIDDK-sponsored workshop.

    PubMed

    Henske, Elizabeth P; Rasooly, Rebekah; Siroky, Brian; Bissler, John

    2014-02-01

    Remarkable basic and translational advances have elucidated the role of the mammalian target of rapamycin (mTOR) signaling network in the pathogenesis of renal disease. Many of these advances originated from studies of the genetic disease tuberous sclerosis complex (TSC), leading to one of the clearest therapeutic opportunities to target mTOR with rapamycin and its analogs ("rapalogs"), which effectively inhibit mTOR complex 1 (mTORC1) by an allosteric mechanism. Clinical trials based on these discoveries have provided strongly positive therapeutic results in TSC (Bissler JJ, McCormack FX, Young LR, Elwing JM, Chuck G, Leonard JM, Schmithorst VJ, Laor T, Brody AS, Bean J, Salisbury S, Franz DN. N Engl J Med 358: 140-151, 2008; Krueger DA, Care MM, Holland K, Agricola K, Tudor C, Mangeshkar P, Wilson KA, Byars A, Sahmoud T, Franz DN. N Engl J Med 363: 1801-1811, 2010; McCormack FX, Inoue Y, Moss J, Singer LG, Strange C, Nakata K, Barker AF, Chapman JT, Brantly ML, Stocks JM, Brown KK, Lynch JP 3rd, Goldberg HJ, Young LR, Kinder BW, Downey GP, Sullivan EJ, Colby TV, McKay RT, Cohen MM, Korbee L, Taveira-DaSilva AM, Lee HS, Krischer JP, Trapnell BC. N Engl J Med 364: 1595-1606, 2011). In June 2013, the National Institute of Diabetes and Digestive and Kidney Diseases convened a small panel of physicians and scientists working in the field to identify key unknowns and define possible "next steps" in advancing understanding of TSC- and mTOR-dependent renal phenotypes. TSC-associated renal disease, which affects >85% of TSC patients, and was a major topic of discussion, focused on angiomyolipomas and epithelial cysts. The third major topic was the role of mTOR and mTOR inhibition in the pathogenesis and therapy of chronic renal disease. Renal cell carcinoma, while recognized as a manifestation of TSC that occurs in a small fraction of patients, was not the primary focus of this workshop and thus was omitted from panel discussions and from this report.

  3. BIM and mTOR expression levels predict outcome to erlotinib in EGFR-mutant non-small-cell lung cancer

    PubMed Central

    Karachaliou, Niki; Codony-Servat, Jordi; Teixidó, Cristina; Pilotto, Sara; Drozdowskyj, Ana; Codony-Servat, Carles; Giménez-Capitán, Ana; Molina-Vila, Miguel Angel; Bertrán-Alamillo, Jordi; Gervais, Radj; Massuti, Bartomeu; Morán, Teresa; Majem, Margarita; Felip, Enriqueta; Carcereny, Enric; García-Campelo, Rosario; Viteri, Santiago; González-Cao, María; Morales-Espinosa, Daniela; Verlicchi, Alberto; Crisetti, Elisabetta; Chaib, Imane; Santarpia, Mariacarmela; Luis Ramírez, José; Bosch-Barrera, Joaquim; Felipe Cardona, Andrés; de Marinis, Filippo; López-Vivanco, Guillermo; Miguel Sánchez, José; Vergnenegre, Alain; Sánchez Hernández, José Javier; Sperduti, Isabella; Bria, Emilio; Rosell, Rafael

    2015-01-01

    BIM is a proapoptotic protein that initiates apoptosis triggered by EGFR tyrosine kinase inhibitors (TKI). mTOR negatively regulates apoptosis and may influence response to EGFR TKI. We examined mRNA expression of BIM and MTOR in 57 patients with EGFR-mutant NSCLC from the EURTAC trial. Risk of mortality and disease progression was lower in patients with high BIM compared with low/intermediate BIM mRNA levels. Analysis of MTOR further divided patients with high BIM expression into two groups, with those having both high BIM and MTOR experiencing shorter overall and progression-free survival to erlotinib. Validation of our results was performed in an independent cohort of 19 patients with EGFR-mutant NSCLC treated with EGFR TKIs. In EGFR-mutant lung adenocarcinoma cell lines with high BIM expression, concomitant high mTOR expression increased IC50 of gefitinib for cell proliferation. We next sought to analyse the signalling pattern in cell lines with strong activation of mTOR and its substrate P-S6. We showed that mTOR and phosphodiesterase 4D (PDE4D) strongly correlate in resistant EGFR-mutant cancer cell lines. These data suggest that the combination of EGFR TKI with mTOR or PDE4 inhibitors could be adequate therapy for EGFR-mutant NSCLC patients with high pretreatment levels of BIM and mTOR. PMID:26639561

  4. BIM and mTOR expression levels predict outcome to erlotinib in EGFR-mutant non-small-cell lung cancer.

    PubMed

    Karachaliou, Niki; Codony-Servat, Jordi; Teixidó, Cristina; Pilotto, Sara; Drozdowskyj, Ana; Codony-Servat, Carles; Giménez-Capitán, Ana; Molina-Vila, Miguel Angel; Bertrán-Alamillo, Jordi; Gervais, Radj; Massuti, Bartomeu; Morán, Teresa; Majem, Margarita; Felip, Enriqueta; Carcereny, Enric; García-Campelo, Rosario; Viteri, Santiago; González-Cao, María; Morales-Espinosa, Daniela; Verlicchi, Alberto; Crisetti, Elisabetta; Chaib, Imane; Santarpia, Mariacarmela; Luis Ramírez, José; Bosch-Barrera, Joaquim; Felipe Cardona, Andrés; de Marinis, Filippo; López-Vivanco, Guillermo; Miguel Sánchez, José; Vergnenegre, Alain; Sánchez Hernández, José Javier; Sperduti, Isabella; Bria, Emilio; Rosell, Rafael

    2015-12-07

    BIM is a proapoptotic protein that initiates apoptosis triggered by EGFR tyrosine kinase inhibitors (TKI). mTOR negatively regulates apoptosis and may influence response to EGFR TKI. We examined mRNA expression of BIM and MTOR in 57 patients with EGFR-mutant NSCLC from the EURTAC trial. Risk of mortality and disease progression was lower in patients with high BIM compared with low/intermediate BIM mRNA levels. Analysis of MTOR further divided patients with high BIM expression into two groups, with those having both high BIM and MTOR experiencing shorter overall and progression-free survival to erlotinib. Validation of our results was performed in an independent cohort of 19 patients with EGFR-mutant NSCLC treated with EGFR TKIs. In EGFR-mutant lung adenocarcinoma cell lines with high BIM expression, concomitant high mTOR expression increased IC50 of gefitinib for cell proliferation. We next sought to analyse the signalling pattern in cell lines with strong activation of mTOR and its substrate P-S6. We showed that mTOR and phosphodiesterase 4D (PDE4D) strongly correlate in resistant EGFR-mutant cancer cell lines. These data suggest that the combination of EGFR TKI with mTOR or PDE4 inhibitors could be adequate therapy for EGFR-mutant NSCLC patients with high pretreatment levels of BIM and mTOR.

  5. Inhibition of mTOR signaling protects photoreceptor cells against serum deprivation by reducing oxidative stress and inducing G2/M cell cycle arrest

    PubMed Central

    FAN, BIN; LI, FU-QAING; SONG, JING-YAO; CHEN, XU; LI, GUANG-YU

    2016-01-01

    The mammalian target of rapamycin (mTOR) pathway is a crucial cellular signaling hub, which integrates internal and external cues to modulate the cell cycle, protein synthesis and metabolism. The present study hypothesized that inhibiting mTOR signaling may induce cells to enter lower and more stable bioenergetic states, in which neurons have greater resistance to various insults. Neurotrophin withdrawal from photoreceptor cells (661W cells) was mimicked using serum deprivation, and the neuroprotective mechanisms were studied following suppression of the mTOR pathway. Treatment with an mTOR specific inhibitor, rapamycin, reduced intracellular levels of reactive oxygen species, suppressed oxidative stress, and attenuated mitochondrial dysfunction. In addition, inhibiting mTOR signaling induced a G2/M cell cycle arrest, thus providing an opportunity to repair damaged DNA and block the cell death cascade. These results suggested that inhibition of mTOR had a neuroprotective effect on serum-deprived 661W cells. In conclusion, the mTOR pathway is a critical molecular signal for cell cycle regulation and energy metabolism, and inhibiting the mTOR pathway may attenuate neurotrophin withdrawal-induced damage. These observations may provide evidence for the treatment of retinal degenerative disease, since inducing neurons into a lower and more stable bioenergetic state by blocking mTOR signaling may slow the progression of neurodegenerative diseases. PMID:27035647

  6. Impact of mTOR expression on clinical outcome in paediatric patients with B-cell acute lymphoblastic leukaemia – preliminary report

    PubMed Central

    Mycko, Katarzyna; Sałacińska-Łoś, Elżbieta; Pastorczak, Agata; Siwicka, Alicja; Młynarski, Wojciech; Matysiak, Michał

    2016-01-01

    Aim of the study To characterise expression of mTOR (mammalian target of rapamycin) in childhood B-cell acute lymphoblastic leukaemia (ALL), and to evaluate a possible link between mTOR and clinical characteristics. Material and methods The examined group consisted of 21 consecutive patients, aged 1–18 years, diagnosed with B-cell ALL in 2010, and 10 relapsed B-cell ALL patients diagnosed for the first time between 2009 and 2011, who developed relapse before 2014. All subjects were treated in the Department of Paediatric Haematology and Oncology of the Medical University of Warsaw according to the ALL-IC BFM 2002 Protocol. We evaluated mTOR and phospho-mTOR expression by immunohistochemistry using rabbit monoclonal antibodies. Results mTOR expression was found to be significantly associated with the risk of relapse and was more frequent in ALL recurrence. No significant relationship was detected between mTOR expression and other features of high-risk disease in paediatric ALL. Conclusions mTOR activity could be considered a high-risk feature in paediatric B-cell ALL. Expression of mTOR kinase is observed remarkably more frequently in disease recurrence than at first diagnosis, indicating higher proliferative and survival potential of leukaemic cells in relapse. Routine analysis of mTOR activity could be performed to select patients that may potentially benefit from mTOR inhibitors (MTI) treatment. PMID:27688725

  7. Impact of mTOR expression on clinical outcome in paediatric patients with B-cell acute lymphoblastic leukaemia – preliminary report

    PubMed Central

    Mycko, Katarzyna; Sałacińska-Łoś, Elżbieta; Pastorczak, Agata; Siwicka, Alicja; Młynarski, Wojciech; Matysiak, Michał

    2016-01-01

    Aim of the study To characterise expression of mTOR (mammalian target of rapamycin) in childhood B-cell acute lymphoblastic leukaemia (ALL), and to evaluate a possible link between mTOR and clinical characteristics. Material and methods The examined group consisted of 21 consecutive patients, aged 1–18 years, diagnosed with B-cell ALL in 2010, and 10 relapsed B-cell ALL patients diagnosed for the first time between 2009 and 2011, who developed relapse before 2014. All subjects were treated in the Department of Paediatric Haematology and Oncology of the Medical University of Warsaw according to the ALL-IC BFM 2002 Protocol. We evaluated mTOR and phospho-mTOR expression by immunohistochemistry using rabbit monoclonal antibodies. Results mTOR expression was found to be significantly associated with the risk of relapse and was more frequent in ALL recurrence. No significant relationship was detected between mTOR expression and other features of high-risk disease in paediatric ALL. Conclusions mTOR activity could be considered a high-risk feature in paediatric B-cell ALL. Expression of mTOR kinase is observed remarkably more frequently in disease recurrence than at first diagnosis, indicating higher proliferative and survival potential of leukaemic cells in relapse. Routine analysis of mTOR activity could be performed to select patients that may potentially benefit from mTOR inhibitors (MTI) treatment.

  8. Oncogenic tyrosine kinase NPM/ALK induces activation of the rapamycin-sensitive mTOR signaling pathway.

    PubMed

    Marzec, M; Kasprzycka, M; Liu, X; El-Salem, M; Halasa, K; Raghunath, P N; Bucki, R; Wlodarski, P; Wasik, M A

    2007-08-16

    The mechanisms of cell transformation mediated by the nucleophosmin (NPM)/anaplastic lymphoma kinase (ALK) tyrosine kinase are only partially understood. Here, we report that cell lines and native tissues derived from the NPM/ALK-expressing T-cell lymphoma display persistent activation of mammalian target of rapamycin (mTOR) as determined by phosphorylation of mTOR targets S6rp and 4E-binding protein 1 (4E-BP1). The mTOR activation is serum growth factor-independent but nutrient-dependent. It is also dependent on the expression and enzymatic activity of NPM/ALK as demonstrated by cell transfection with wild-type and functionally deficient NPM/ALK, small interfering RNA (siRNA)-mediated NPM/ALK depletion and kinase activity suppression using the inhibitor WHI-P154. The NPM/ALK-induced mTOR activation is transduced through the mitogen-induced extracellular kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathway and, to a much lesser degree, through the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway. Accordingly, whereas the low-dose PI3K inhibitor wortmannin and Akt inhibitor III profoundly inhibited Akt phosphorylation, they had a very modest effect on S6rp and 4E-BP1 phosphorylation. In turn, MEK inhibitors U0126 and PD98059 and siRNA-mediated depletion of either ERK1 or ERK2 inhibited S6rp phosphorylation much more effectively. Finally, the mTOR inhibitor rapamycin markedly decreased proliferation and increased the apoptotic rate of ALK+TCL cells. These findings identify mTOR as a novel key target of NPM/ALK and suggest that mTOR inhibitors may prove effective in therapy of ALK-induced malignancies.

  9. mTOR inhibitors blunt the p53 response to nucleolar stress by regulating RPL11 and MDM2 levels.

    PubMed

    Goudarzi, Kaveh M; Nistér, Monica; Lindström, Mikael S

    2014-01-01

    Mechanistic target of rapamycin (mTOR) is a master regulator of cell growth through its ability to stimulate ribosome biogenesis and mRNA translation. In contrast, the p53 tumor suppressor negatively controls cell growth and is activated by a wide range of insults to the cell. The mTOR and p53 signaling pathways are connected by a number of different mechanisms. Chemotherapeutics that inhibit ribosome biogenesis often induce nucleolar stress and activation of p53. Here we have investigated how the p53 response to nucleolar stress is affected by simultaneous mTOR inhibition in osteosarcoma and glioma cell lines. We found that inhibitors of the mTOR pathway including rapamycin, wortmannin, and caffeine blunted the p53 response to nucleolar stress induced by actinomycin D. Synthetic inhibitors of mTOR (temsirolimus, LY294.002 and PP242) also impaired actinomycin D triggered p53 stabilization and induction of p21. Ribosomal protein (RPL11) is known to be required for p53 protein stabilization following nucleolar stress. Treatment of cells with mTOR inhibitors may lead to reduced synthesis of RPL11 and thereby destabilize p53. We found that rapamycin mimicked the effect of RPL11 depletion in terms of blunting the p53 response to nucleolar stress. However, the extent to which the levels of p53 and RPL11 were reduced by rapamycin varied between cell lines. Additional mechanisms whereby rapamycin blunts the p53 response to nucleolar stress are likely to be involved. Indeed, rapamycin increased the levels of endogenous MDM2 despite inhibition of its phosphorylation at Ser-166. Our findings may have implications for the design of combinatorial cancer treatments with mTOR pathway inhibitors.

  10. Kinome RNAi Screens Reveal Synergistic Targeting of MTOR and FGFR1 Pathways for Treatment of Lung Cancer and HNSCC

    PubMed Central

    Singleton, Katherine R.; Hinz, Trista K.; Kleczko, Emily K.; Marek, Lindsay A.; Kwak, Jeff; Harp, Taylor; Kim, Jihye; Tan, Aik Choon; Heasley, Lynn E.

    2015-01-01

    The fibroblast growth factor receptor FGFR1 is a therapeutic target under investigation in multiple solid tumors and clinical trials of selective tyrosine kinase inhibitors (TKI) are underway. Treatment with single TKI represents a logical step towards personalized cancer therapy, but intrinsic and acquired resistance mechanisms limit their long-term benefit. In this study, we deployed RNAi-based functional genomic screens to identify protein kinases controlling the intrinsic sensitivity of FGFR1-dependent lung cancer and head and neck squamous cell cancer (HNSCC) cells to ponatinib, a multi-kinase FGFR-active inhibitor. We identified and validated a synthetic lethal interaction between Mammalian Target of Rapamycin (MTOR) and ponatinib in non-small cell lung carcinoma cells. Additionally, treatment with MTOR-targeting shRNAs and pharmacological inhibitors revealed that MTOR is an essential protein kinase in other FGFR1-expressing cancer cells. The combination of FGFR inhibitors and MTOR or AKT inhibitors resulted in synergistic growth suppression in vitro. Notably, tumor xenografts generated from FGFR1-dependent lung cancer cells exhibited only modest sensitivity to monotherapy with the FGFR-specific TKI, AZD4547, but when combined with the MTOR inhibitor, AZD2014, significantly attenuated tumor growth and prolonged survival. Our findings support the existence of a signaling network wherein FGFR1-driven ERK and activated MTOR/AKT represent distinct arms required to induce full transformation. Further, they suggest clinical efficacy of treatments for FGFR1-driven lung cancers and HNSCC may be achieved by combining MTOR inhibitors and FGFR-specific TKIs. PMID:26359452

  11. PKM2 enhances chemosensitivity to cisplatin through interaction with the mTOR pathway in cervical cancer

    PubMed Central

    Zhu, Haiyan; Wu, Jun; Zhang, Wenwen; Luo, Hui; Shen, Zhaojun; Cheng, Huihui; Zhu, Xueqiong

    2016-01-01

    Pyruvate kinase M2 (PKM2) is a key driver of aerobic glycolysis in cancer cells and has been shown to be up-regulated by mTOR in vitro. Our previous proteomic profiling studies showed that PKM2 was significantly upregulated in cervical cancer tissues after treatment with neoadjuvant chemotherapy (NACT). Whether PKM2 expression predicts cisplatin-based NACT sensitivity and is mTOR dependent in cervical cancer patients remains unclear. Using paired tumor samples (pre- and post-chemotherapy) from 36 cervical cancer patients, we examined mTOR, HIF-1α, c-Myc, and PKM2 expression in cervical cancer samples and investigated the response to cisplatin-based NACT. In addition, we established PKM2 suppressed cervical cancer cell lines and evaluated their sensitivity to cisplatin in vitro. We found that the mTOR/HIF-1α/c-Myc/PKM2 signaling pathway was significantly downregulated in post-chemotherapy cervical cancer tissues. High levels of mTOR, HIF-1α, c-Myc, and PKM2 were associated with a positive chemotherapy response in cervical cancer patients treated with cisplatin-based NACT. In vitro, PKM2 knockdown desensitized cervical cancer cells to cisplatin. Moreover, PKM2 had complex interactions with mTOR pathways. mTOR, HIF1α, c-Myc, and PKM2 expression in cervical cancer may serve as predictive biomarkers to cisplatin-based chemotherapy. PKM2 enhances chemosensitivity to cisplatin through interaction with the mTOR pathway in cervical cancer. PMID:27492148

  12. Dual targeting of mTOR and Aurora-A kinase for the treatment of uterine leiomyosarcoma

    PubMed Central

    Savannah, Kari Brewer; Demicco, Elizabeth G.; Lusby, Kristelle; Ghadimi, Markus PH.; Belousov, Roman; Young, Eric; Zhang, Yiqun; Huang, Kai-Lieh; Lazar, Alexander J.; Hunt, Kelly K.; Pollock, Raphael E.; Creighton, Chad J.; Anderson, Matthew L.; Lev, Dina

    2012-01-01

    Purpose The significance of mTOR activation in uterine leiomyosarcoma (ULMS) and its potential as a therapeutic target were investigated. Furthermore, given that effective therapies likely require combination mTOR blockade with inhibition of other targets, coupled with recent observations suggesting that Aurora-A kinase (Aurk-A) deregulations commonly occur in ULMS, the preclinical impact of dually targeting both pathways was evaluated. Experimental design Immunohistochemical staining was used to evaluate expression of activated mTOR componentry in a large (>200 samples) ULMS tissue microarray. Effects of mTOR blockade (using rapamycin) and Aurk-A inhibition (using MLN8237) alone and in combination on human ULMS cell growth, cell-cycle progression, and apoptosis were assessed in cellular assays. Drug interactions were determined via combination index (CI) analyses. The anti-tumor effects of inhibitors alone or in combination were evaluated in vivo. Results Enhanced mTOR activation was seen in human ULMS samples. Increased pS6RP and p4EBP1 expression correlated with disease progression; p4EBP1 was found to be an independent prognosticator of patient outcome. Rapamycin inhibited growth and cell cycle progression of ULMS cell strains/lines in culture. However, only a cytostatic effect on tumor growth was found in vivo. Combining rapamycin with MLN8237 profoundly (and synergistically) abrogated ULMS cells’ growth in culture; interestingly, these effects were seen only when MLN8237 was pre-administered. This novel therapeutic combination and scheduling regimen resulted in marked tumor growth inhibition in vivo. Conclusions mTOR and Aurk-A pathways are commonly deregulated in ULMS. Preclinical data support further exploration of dual mTOR and Aurk-A therapeutic blockade for human ULMS. PMID:22821997

  13. Fisetin induces autophagic cell death through suppression of mTOR signaling pathway in prostate cancer cells

    PubMed Central

    Suh, Yewseok; Afaq, Farrukh; Khan, Naghma; Johnson, Jeremy J.; Khusro, Fatima H.; Mukhtar, Hasan

    2010-01-01

    The mammalian target of rapamycin (mTOR) kinase is an important component of PTEN/PI3K/Akt signaling pathway, which is frequently deregulated in prostate cancer (CaP). Recent studies suggest that targeting PTEN/PI3K/Akt and mTOR signaling pathway could be an effective strategy for the treatment of hormone refractory CaP. Here, we show that the treatment of androgen-independent and PTEN-negative human CaP PC3 cells with fisetin, a dietary flavonoid, resulted in inhibition of mTOR kinase signaling pathway. Treatment of cells with fisetin inhibited mTOR activity and downregulated Raptor, Rictor, PRAS40 and GβL that resulted in loss of mTOR complexes (mTORC)1/2 formation. Fisetin also activated the mTOR repressor TSC2 through inhibition of Akt and activation of AMPK. Fisetin-mediated inhibition of mTOR resulted in hypophosphorylation of 4EBP1 and suppression of Cap-dependent translation. We also found that fisetin treatment leads to induction of autophagic-programmed cell death rather than cytoprotective autophagy as shown by small interfering RNA Beclin1-knockdown and autophagy inhibitor. Taken together, we provide evidence that fisetin functions as a dual inhibitor of mTORC1/2 signaling leading to inhibition of Cap-dependent translation and induction of autophagic cell death in PC3 cells. These results suggest that fisetin could be a useful chemotherapeutic agent in treatment of hormone refractory CaP. PMID:20530556

  14. Prevention of irradiation-induced salivary hypofunction by rapamycin in swine parotid glands

    PubMed Central

    Zhu, Zhao; Pang, Baoxing; Iglesias-Bartolome, Ramiro; Wu, Xiaoshan; Hu, Lei; Zhang, Chunmei; Wang, Jinsong; Silvio Gutkind, J; Wang, Songlin

    2016-01-01

    Radiotherapy is commonly used in patients with oral cavity and pharyngeal cancers, usually resulting in irreversible salivary hypofunction. Currently management of radiation damage to salivary glands still remains a great challenge. Recent studies show that activation of mammalian target of rapamycin (mTOR) occurs in salivary gland lesions, making it possible to apply mTOR inhibitor for treatment. Our results indicate inhibition of mTOR by rapamycin significantly alleviated irradiation-induced salivary hypofunction by restoring 46% salivary flow rate and protecting histological structures in swine. Furthermore, rapamycin protected human submandibular gland cell line (HSG) from irradiation-induced cell depletion and loss of cell proliferation capacity. These findings lay the foundation for a new clinical application of rapamycin to prevent irradiation-induced salivary hypofunction. PMID:26958808

  15. Tuberous sclerosis complex suppression in cerebellar development and medulloblastoma: separate regulation of mTOR activity and p27Kip1 localization

    PubMed Central

    Bhatia, Bobby; Northcott, Paul A.; Hambardzumyan, Dolores; Govindarajan, Baskaran; Brat, Daniel J.; Arbiser, Jack L.; Holland, Eric C.; Taylor, Michael D.; Kenney, Anna Marie

    2009-01-01

    During development, proliferation of cerebellar granule neuron precursors (CGNPs), candidate cells-of-origin for the pediatric brain tumor medulloblastoma, requires signaling by Sonic hedgehog (Shh) and insulin-like growth factor (IGF), whose pathways are also implicated in medulloblastoma. One of the consequences of IGF signaling is inactivation of the mTOR-suppressing Tuberous Sclerosis Complex (TSC), comprised of TSC1 and TSC2, leading to increased mRNA translation. We show that mice in which TSC function is impaired display increased mTOR pathway activation, enhanced CGNP proliferation, GSK-3α/β inactivation, and cytoplasmic localization of the cyclin-dependent kinase (cdk) inhibitor p27Kip1, which has been proposed to cause its inactivation or gain of oncogenic functions. We observed the same characteristics in wild-type primary cultures of CGNPs in which TSC1 and/or TSC2 were knocked down, and in mouse medulloblastomas induced by ectopic Shh pathway activation. Moreover, Shh-induced mouse medulloblastomas manifested Akt-mediated TSC2 inactivation, and the mutant TSC2 allele synergized with aberrant Shh signaling to increase medulloblastoma incidence in mice. Driving exogenous TSC2 expression in Shh-induced medulloblastoma cells corrected p27Kip1 localization and reduced proliferation. GSK-3α/β inactivation in the tumors in vivo and in primary CGNP cultures was mTOR-dependent, whereas p27Kip1 cytoplasmic localization was regulated upstream of mTOR, by TSC2. These results indicate that a balance between Shh mitogenic signaling and TSC function regulating new protein synthesis and cdk inhibition is essential for normal development and prevention of tumor formation or expansion. PMID:19738049

  16. mTOR signaling promotes stem cell activation via counterbalancing BMP-mediated suppression during hair regeneration.

    PubMed

    Deng, Zhili; Lei, Xiaohua; Zhang, Xudong; Zhang, Huishan; Liu, Shuang; Chen, Qi; Hu, Huimin; Wang, Xinyue; Ning, Lina; Cao, Yujing; Zhao, Tongbiao; Zhou, Jiaxi; Chen, Ting; Duan, Enkui

    2015-02-01

    Hair follicles (HFs) undergo cycles of degeneration (catagen), rest (telogen), and regeneration (anagen) phases. Anagen begins when the hair follicle stem cells (HFSCs) obtain sufficient activation cues to overcome suppressive signals, mainly the BMP pathway, from their niche cells. Here, we unveil that mTOR complex 1 (mTORC1) signaling is activated in HFSCs, which coincides with the HFSC activation at the telogen-to-anagen transition. By using both an inducible conditional gene targeting strategy and a pharmacological inhibition method to ablate or inhibit mTOR signaling in adult skin epithelium before anagen initiation, we demonstrate that HFs that cannot respond to mTOR signaling display significantly delayed HFSC activation and extended telogen. Unexpectedly, BMP signaling activity is dramatically prolonged in mTOR signaling-deficient HFs. Through both gain- and loss-of-function studies in vitro, we show that mTORC1 signaling negatively affects BMP signaling, which serves as a main mechanism whereby mTORC1 signaling facilitates HFSC activation. Indeed, in vivo suppression of BMP by its antagonist Noggin rescues the HFSC activation defect in mTORC1-null skin. Our findings reveal a critical role for mTOR signaling in regulating stem cell activation through counterbalancing BMP-mediated repression during hair regeneration. PMID:25609845

  17. Co-regulation of SREBP-1 and mTOR ameliorates lipid accumulation in kidney of diabetic mice.

    PubMed

    Wang, Hui; Zhu, Lin; Hao, Jun; Duan, Huijun; Liu, Shuxia; Zhao, Song; Liu, Qingjuan; Liu, Wei

    2015-08-01

    SREBP-1 and mTOR have been proved to involve in renal lipid metabolism of diabetes mellitus. In the present study, we investigated the effect of co-regulation of SREBP-1 and mTOR on renal lipid metabolism using diabetic mice and cultured renal tubular cells. The results showed that compared with those in high glucose-stimulated HKC cells single transfected with shRNA-SREBP-1 vector, the level of SREBP-1 protein were significantly reduced by 64.1% followed by decreased FASN mRNA, ACC mRNA, ADRP protein and lipid droplets in HKC cells co-transfected with shRNA-SREBP-1 vector and kinase-dead mTOR vector. Furthermore, diabetic mice co-injected with shRNA-SREBP-1 vector and kinase-dead mTOR vector showed that renal SREBP-1 protein, FASN mRNA and ACC mRNA were respectively decreased by 34.6%, 45.9%, 22.0% in comparison with those in diabetic mice single injected with shRNA-SREBP-1 vector accompanied by reduced ADRP protein and triglyceride content. In the end our study suggests that co-regulation of SREBP-1 and mTOR in kidney of diabetic mice is more effective in lowering renal lipogenesis than only regulation of SREBP-1. PMID:26112216

  18. Discovering new mTOR inhibitors for cancer treatment through virtual screening methods and in vitro assays

    NASA Astrophysics Data System (ADS)

    Wang, Ling; Chen, Lei; Yu, Miao; Xu, Li-Hui; Cheng, Bao; Lin, Yong-Sheng; Gu, Qiong; He, Xian-Hui; Xu, Jun

    2016-01-01

    Mammalian target of rapamycin (mTOR) is an attractive target for new anticancer drug development. We recently developed in silico models to distinguish mTOR inhibitors and non-inhibitors. In this study, we developed an integrated strategy for identifying new mTOR inhibitors using cascaded in silico screening models. With this strategy, fifteen new mTOR kinase inhibitors including four compounds with IC50 values below 10 μM were discovered. In particular, compound 17 exhibited potent anticancer activities against four tumor cell lines, including MCF-7, HeLa, MGC-803, and C6, with IC50 values of 1.90, 2.74, 3.50 and 11.05 μM. Furthermore, cellular studies and western blot analyses revealed that 17 induces cell death via apoptosis by targeting both mTORC1 and mTORC2 within cells and arrests the cell cycle of HeLa at the G1/G0-phase. Finally, multi-nanosecond explicit solvent simulations and MM/GBSA analyses were carried out to study the inhibitory mechanisms of 13, 17, and 40 for mTOR. The potent compounds presented here are worthy of further investigation.

  19. Regulation of YAP by mTOR and autophagy reveals a therapeutic target of tuberous sclerosis complex.

    PubMed

    Liang, Ning; Zhang, Chi; Dill, Patricia; Panasyuk, Ganna; Pion, Delphine; Koka, Vonda; Gallazzini, Morgan; Olson, Eric N; Lam, Hilaire; Henske, Elizabeth P; Dong, Zheng; Apte, Udayan; Pallet, Nicolas; Johnson, Randy L; Terzi, Fabiola; Kwiatkowski, David J; Scoazec, Jean-Yves; Martignoni, Guido; Pende, Mario

    2014-10-20

    Genetic studies have shown that the tuberous sclerosis complex (TSC) 1-TSC2-mammalian target of Rapamycin (mTOR) and the Hippo-Yes-associated protein 1 (YAP) pathways are master regulators of organ size, which are often involved in tumorigenesis. The crosstalk between these signal transduction pathways in coordinating environmental cues, such as nutritional status and mechanical constraints, is crucial for tissue growth. Whether and how mTOR regulates YAP remains elusive. Here we describe a novel mouse model of TSC which develops renal mesenchymal lesions recapitulating human perivascular epithelioid cell tumors (PEComas) from patients with TSC. We identify that YAP is up-regulated by mTOR in mouse and human PEComas. YAP inhibition blunts abnormal proliferation and induces apoptosis of TSC1-TSC2-deficient cells, both in culture and in mosaic Tsc1 mutant mice. We further delineate that YAP accumulation in TSC1/TSC2-deficient cells is due to impaired degradation of the protein by the autophagosome/lysosome system. Thus, the regulation of YAP by mTOR and autophagy is a novel mechanism of growth control, matching YAP activity with nutrient availability under growth-permissive conditions. YAP may serve as a potential therapeutic target for TSC and other diseases with dysregulated mTOR activity. PMID:25288394

  20. Amino-functionalized nanoparticles as inhibitors of mTOR and inducers of cell cycle arrest in leukemia cells.

    PubMed

    Loos, Cornelia; Syrovets, Tatiana; Musyanovych, Anna; Mailänder, Volker; Landfester, Katharina; Simmet, Thomas

    2014-02-01

    Activation of the mammalian target of rapamycin (mTOR) has been implicated in anticancer drug resistance, type 2 diabetes, and aging. Here, we show that surface functionalization of polystyrene nanoparticles with amino groups (PS-NH2), but not with carboxyl groups (PS-COOH), induces G2 cell-cycle arrest and inhibition of proliferation in three leukemia cell lines. Besides, PS-NH2 inhibit angiogenesis and proliferation of leukemia cells xenografted onto the chick chorioallantoic membrane. At the molecular level, PS-NH2 inhibit, whereas PS-COOH activate mTOR signaling in leukemia cells. Consistently, PS-NH2 block activation of the mTOR downstream targets, Akt and p70 ribosomal S6 kinase 1, and induce overexpression of the cell-cycle regulator p21(Cip1/Waf1) and degradation of cyclin B1. After addition, both types of particles rapidly induce autophagy in leukemia cells. Yet, only in PS-NH2-treated cells, acidic vesicular organelles show elevated pH and impaired processing of procathepsin B. Moreover, solely in PS-NH2-treated cells, autophagy is followed by permeabilization of acidic vesicular organelles and induction of apoptosis. By contrast, primary macrophages, which do not exhibit activated mTOR signaling, proved relatively resistant to PS-NH2-induced toxicity. These data indicate that functionalized nanoparticles can be used to control activation of mTOR signaling pathways, and to influence proliferation and viability of malignant cells.

  1. mTOR signaling promotes stem cell activation via counterbalancing BMP-mediated suppression during hair regeneration.

    PubMed

    Deng, Zhili; Lei, Xiaohua; Zhang, Xudong; Zhang, Huishan; Liu, Shuang; Chen, Qi; Hu, Huimin; Wang, Xinyue; Ning, Lina; Cao, Yujing; Zhao, Tongbiao; Zhou, Jiaxi; Chen, Ting; Duan, Enkui

    2015-02-01

    Hair follicles (HFs) undergo cycles of degeneration (catagen), rest (telogen), and regeneration (anagen) phases. Anagen begins when the hair follicle stem cells (HFSCs) obtain sufficient activation cues to overcome suppressive signals, mainly the BMP pathway, from their niche cells. Here, we unveil that mTOR complex 1 (mTORC1) signaling is activated in HFSCs, which coincides with the HFSC activation at the telogen-to-anagen transition. By using both an inducible conditional gene targeting strategy and a pharmacological inhibition method to ablate or inhibit mTOR signaling in adult skin epithelium before anagen initiation, we demonstrate that HFs that cannot respond to mTOR signaling display significantly delayed HFSC activation and extended telogen. Unexpectedly, BMP signaling activity is dramatically prolonged in mTOR signaling-deficient HFs. Through both gain- and loss-of-function studies in vitro, we show that mTORC1 signaling negatively affects BMP signaling, which serves as a main mechanism whereby mTORC1 signaling facilitates HFSC activation. Indeed, in vivo suppression of BMP by its antagonist Noggin rescues the HFSC activation defect in mTORC1-null skin. Our findings reveal a critical role for mTOR signaling in regulating stem cell activation through counterbalancing BMP-mediated repression during hair regeneration.

  2. Regulation of YAP by mTOR and autophagy reveals a therapeutic target of tuberous sclerosis complex

    PubMed Central

    Liang, Ning; Zhang, Chi; Dill, Patricia; Panasyuk, Ganna; Pion, Delphine; Koka, Vonda; Gallazzini, Morgan; Olson, Eric N.; Lam, Hilaire; Henske, Elizabeth P.; Dong, Zheng; Apte, Udayan; Pallet, Nicolas; Johnson, Randy L.; Terzi, Fabiola; Kwiatkowski, David J.; Scoazec, Jean-Yves; Martignoni, Guido

    2014-01-01

    Genetic studies have shown that the tuberous sclerosis complex (TSC) 1–TSC2–mammalian target of Rapamycin (mTOR) and the Hippo–Yes-associated protein 1 (YAP) pathways are master regulators of organ size, which are often involved in tumorigenesis. The crosstalk between these signal transduction pathways in coordinating environmental cues, such as nutritional status and mechanical constraints, is crucial for tissue growth. Whether and how mTOR regulates YAP remains elusive. Here we describe a novel mouse model of TSC which develops renal mesenchymal lesions recapitulating human perivascular epithelioid cell tumors (PEComas) from patients with TSC. We identify that YAP is up-regulated by mTOR in mouse and human PEComas. YAP inhibition blunts abnormal proliferation and induces apoptosis of TSC1–TSC2-deficient cells, both in culture and in mosaic Tsc1 mutant mice. We further delineate that YAP accumulation in TSC1/TSC2-deficient cells is due to impaired degradation of the protein by the autophagosome/lysosome system. Thus, the regulation of YAP by mTOR and autophagy is a novel mechanism of growth control, matching YAP activity with nutrient availability under growth-permissive conditions. YAP may serve as a potential therapeutic target for TSC and other diseases with dysregulated mTOR activity. PMID:25288394

  3. Amino-functionalized nanoparticles as inhibitors of mTOR and inducers of cell cycle arrest in leukemia cells.

    PubMed

    Loos, Cornelia; Syrovets, Tatiana; Musyanovych, Anna; Mailänder, Volker; Landfester, Katharina; Simmet, Thomas

    2014-02-01

    Activation of the mammalian target of rapamycin (mTOR) has been implicated in anticancer drug resistance, type 2 diabetes, and aging. Here, we show that surface functionalization of polystyrene nanoparticles with amino groups (PS-NH2), but not with carboxyl groups (PS-COOH), induces G2 cell-cycle arrest and inhibition of proliferation in three leukemia cell lines. Besides, PS-NH2 inhibit angiogenesis and proliferation of leukemia cells xenografted onto the chick chorioallantoic membrane. At the molecular level, PS-NH2 inhibit, whereas PS-COOH activate mTOR signaling in leukemia cells. Consistently, PS-NH2 block activation of the mTOR downstream targets, Akt and p70 ribosomal S6 kinase 1, and induce overexpression of the cell-cycle regulator p21(Cip1/Waf1) and degradation of cyclin B1. After addition, both types of particles rapidly induce autophagy in leukemia cells. Yet, only in PS-NH2-treated cells, acidic vesicular organelles show elevated pH and impaired processing of procathepsin B. Moreover, solely in PS-NH2-treated cells, autophagy is followed by permeabilization of acidic vesicular organelles and induction of apoptosis. By contrast, primary macrophages, which do not exhibit activated mTOR signaling, proved relatively resistant to PS-NH2-induced toxicity. These data indicate that functionalized nanoparticles can be used to control activation of mTOR signaling pathways, and to influence proliferation and viability of malignant cells. PMID:24331713

  4. Discovering new mTOR inhibitors for cancer treatment through virtual screening methods and in vitro assays

    PubMed Central

    Wang, Ling; Chen, Lei; Yu, Miao; Xu, Li-Hui; Cheng, Bao; Lin, Yong-Sheng; Gu, Qiong; He, Xian-Hui; Xu, Jun

    2016-01-01

    Mammalian target of rapamycin (mTOR) is an attractive target for new anticancer drug development. We recently developed in silico models to distinguish mTOR inhibitors and non-inhibitors. In this study, we developed an integrated strategy for identifying new mTOR inhibitors using cascaded in silico screening models. With this strategy, fifteen new mTOR kinase inhibitors including four compounds with IC50 values below 10 μM were discovered. In particular, compound 17 exhibited potent anticancer activities against four tumor cell lines, including MCF-7, HeLa, MGC-803, and C6, with IC50 values of 1.90, 2.74, 3.50 and 11.05 μM. Furthermore, cellular studies and western blot analyses revealed that 17 induces cell death via apoptosis by targeting both mTORC1 and mTORC2 within cells and arrests the cell cycle of HeLa at the G1/G0-phase. Finally, multi-nanosecond explicit solvent simulations and MM/GBSA analyses were carried out to study the inhibitory mechanisms of 13, 17, and 40 for mTOR. The potent compounds presented here are worthy of further investigation. PMID:26732172

  5. mTOR ATP-competitive inhibitor INK128 inhibits neuroblastoma growth via blocking mTORC signaling.

    PubMed

    Zhang, Huiyuan; Dou, Jun; Yu, Yang; Zhao, Yanling; Fan, Yihui; Cheng, Jin; Xu, Xin; Liu, Wei; Guan, Shan; Chen, Zhenghu; shi, Yan; Patel, Roma; Vasudevan, Sanjeev A; Zage, Peter E; Zhang, Hong; Nuchtern, Jed G; Kim, Eugene S; Fu, Songbin; Yang, Jianhua

    2015-01-01

    High-risk neuroblastoma often develops resistance to high-dose chemotherapy. The mTOR signaling cascade is frequently deregulated in human cancers and targeting mTOR signaling sensitizes many cancer types to chemotherapy. Here, using a panel of neuroblastoma cell lines, we found that the mTOR inhibitor INK128 showed inhibitory effects on both anchorage-dependent and independent growth of neuroblastoma cells and significantly enhanced the cytotoxic effects of doxorubicin (Dox) on these cell lines. Treatment of neuroblastoma cells with INK128 blocked the activation of downstream mTOR signaling and enhanced Dox-induced apoptosis. Moreover, INK128 was able to overcome the established chemoresistance in the LA-N-6 cell line. Using an orthotopic neuroblastoma mouse model, we found that INK128 significantly inhibited tumor growth in vivo. In conclusion, we have shown that INK128-mediated mTOR inhibition possessed substantial antitumor activity and could significantly increase the sensitivity of neuroblastoma cells to Dox therapy. Taken together, our results indicate that using INK128 can provide additional efficacy to current chemotherapeutic regimens and represent a new paradigm in restoring drug sensitivity in neuroblastoma.

  6. mTOR mediates human trophoblast invasion through regulation of matrix-remodeling enzymes and is associated with serine phosphorylation of STAT3

    SciTech Connect

    Busch, Susann; Renaud, Stephen J.; Schleussner, Ekkehard; Graham, Charles H.; Markert, Udo R.

    2009-06-10

    The intracellular signaling molecule mammalian target of rapamycin (mTOR) is essential for cell growth and proliferation. It is involved in mouse embryogenesis, murine trophoblast outgrowth and linked to tumor cell invasiveness. In order to assess the role of mTOR in human trophoblast invasion we analyzed the in vitro invasiveness of HTR-8/SVneo immortalized first-trimester trophoblast cells in conjunction with enzyme secretion upon mTOR inhibition and knockdown of mTOR protein expression. Additionally, we also tested the capability of mTOR to trigger signal transducer and activator of transcription (STAT)-3 by its phosphorylation status. Rapamycin inhibited mTOR kinase activity as demonstrated with a lower phosphorylation level of the mTOR substrate p70 S6 kinase (S6K). With the use of rapamycin and siRNA-mediated mTOR knockdown we could show that cell proliferation, invasion and secretion of matrix-metalloproteinases (MMP)-2 and -9, urokinase-like plasminogen activator (uPA) and its major physiological uPA inhibitor (PAI)-1 were inhibited. While tyrosine phosphorylation of STAT3 was unaffected by mTOR inhibition and knockdown, serine phosphorylation was diminished. We conclude that mTOR signaling is one major mechanism in a tightly regulated network of intracellular signal pathways including the JAK/STAT system to regulate invasion in human trophoblast cells by secretion of enzymes that remodel the extra-cellular matrix (ECM) such as MMP-2, -9, uPA and PAI-1. Dysregulation of mTOR may contribute to pregnancy-related pathologies caused through impaired trophoblast invasion.

  7. ARG2 impairs endothelial autophagy through regulation of MTOR and PRKAA/AMPK signaling in advanced atherosclerosis

    PubMed Central

    Xiong, Yuyan; Yepuri, Gautham; Forbiteh, Michael; Yu, Yi; Montani, Jean-Pierre; Yang, Zhihong; Ming, Xiu-Fen

    2015-01-01

    Impaired autophagy function and enhanced ARG2 (arginase 2)-MTOR (mechanistic target of rapamycin) crosstalk are implicated in vascular aging and atherosclerosis. We are interested in the role of ARG2 and the potential underlying mechanism(s) in modulation of endothelial autophagy. Using human nonsenescent “young” and replicative senescent endothelial cells as well as Apolipoprotein E-deficient (apoe−/−Arg2+/+) and Arg2-deficient apoe−/− (apoe−/−arg2−/−) mice fed a high-fat diet for 10 wk as the atherosclerotic animal model, we show here that overexpression of ARG2 in the young cells suppresses endothelial autophagy with concomitant enhanced expression of RICTOR, the essential component of the MTORC2 complex, leading to activation of the AKT-MTORC1-RPS6KB1/S6K1 (ribosomal protein S6 kinase, 70kDa, polypeptide 1) cascade and inhibition of PRKAA/AMPK (protein kinase, AMP-activated, α catalytic subunit). Expression of an inactive ARG2 mutant (H160F) had the same effect. Moreover, silencing RPS6KB1 or expression of a constitutively active PRKAA prevented autophagy suppression by ARG2 or H160F. In senescent cells, enhanced ARG2-RICTOR-AKT-MTORC1-RPS6KB1 and decreased PRKAA signaling and autophagy were observed, which was reversed by silencing ARG2 but not by arginase inhibitors. In line with the above observations, genetic ablation of Arg2 in apoe−/− mice reduced RPS6KB1, enhanced PRKAA signaling and endothelial autophagy in aortas, which was associated with reduced atherosclerosis lesion formation. Taken together, the results demonstrate that ARG2 impairs endothelial autophagy independently of the L-arginine ureahydrolase activity through activation of RPS6KB1 and inhibition of PRKAA, which is implicated in atherogenesis. PMID:25484082

  8. Methods to identify molecular expression of mTOR pathway: a rationale approach to stratify patients affected by clear cell renal cell carcinoma for more likely response to mTOR inhibitors

    PubMed Central

    Fiorini, Claudia; Massari, Francesco; Pedron, Serena; Sanavio, Sara; Ciccarese, Chiara; Porcaro, Antonio Benito; Artibani, Walter; Bertoldo, Francesco; Zampini, Claudia; Sava, Teodoro; Ficial, Miriam; Caliò, Anna; Chilosi, Marco; D’Amuri, Alessandro; Sanguedolce, Francesca; Tortora, Giampaolo; Scarpa, Aldo; Delahunt, Brett; Porta, Camillo; Martignoni, Guido; Brunelli, Matteo

    2014-01-01

    Since target therapy with mTOR inhibitors plays an important role in the current management of clear cell renal cell carcinoma (RCC), there is an increasing demand for predictive biomarkers, which may help to select patients that are most likely to benefit from personalized treatment. When dealing with formalin-fixed paraffin-embedded (FFPE) cancer tissue specimens, several techniques may be used to identify potential molecular markers, yielding different outcome in terms of accuracy. We sought to investigate and compare the capability of three main techniques to detect molecules performing an active function in mTOR pathway in RCC. Immunohistochemistry (IHC), Western blot (WB) and immunofluorescence (IF) analyses were performed on FFPE RCC tissue specimens from 16 patients by using the following mTOR pathway-related: mTOR (Ser235/236), phospho-mTOR (p-mTOR/Ser2448), phospho-p70S6k (p-p70S6k/Thr389), both monoclonal and polyclonal, phospho-S6Rb (p-S6Rb) and phospho-4EBP1 (p-4EBP1/Thr37/46). No single molecule was simultaneously revealed by all three techniques. Only p-p70S6k was detected by two methods (IHC and IF) using a monoclonal antibody. The other molecules were detected exclusively by one technique, as follows: p-mTOR and polyclonal p-p70S6K by IHC, p70S6K, p-S6Rb and p-4EBP1 by WB, and, finally, mTOR by IF. We found significant differences in detecting mTOR pathway-related active biomarkers by using three common techniques such as IHC, WB and IF on RCC samples. Such results have important implications in terms of predictive biomarker testing, and need to be related to clinical end-points such as responsiveness to targeted drugs by prospective studies. PMID:25520878

  9. Ulinastatin protects cardiomyocytes against ischemia‑reperfusion injury by regulating autophagy through mTOR activation.

    PubMed

    Xiao, Jian; Zhu, Xiaoyan; Ji, Guangyu; Yang, Qian; Kang, Bo; Zhao, Jianquan; Yao, Feng; Wu, Lihui; Ni, Xin; Wang, Zhinong

    2014-10-01

    Autophagy is significant in myocardial ischemia-reperfusion (IR) injury. Ulinastatin has been demonstrated to protect cardiomyocytes against IR through inducing anti-inflammatory effects. However, whether ulinastatin has an anti‑autophagic effect is yet to be elucidated. The present study aimed to investigate the effect of ulinastatin on the regulation of autophagy during IR injury. Cardiomyocytes of neonatal rats were randomly divided into control, hypoxia-reoxygenation (HR) and ulinastatin groups. In order to investigate whether mammalian target of rapamycin (mTOR) is involved in mediating the protective effect of ulinastatin, cells were treated with the mTOR inhibitor, rapamycin 30 min prior to ulinastatin treatment. To demonstrate the anti-autophagic effect of ulinastatin in vivo, a rat IR model was established. Ulinastatin (1x104 U/kg body weight) was administered 30 min prior to the induction of IR via peritoneal injection. Light chain 3 (LC3), phosphorylated (p)‑mTOR, p‑protein kinase B (Akt) and p‑P70S6 kinase (p‑P70S6K) protein expression were assessed using western blot analysis. In addition, cell vitality, myocardial infarct size and lactate dehydrogenase (LDH) levels were measured. LC3‑Ⅱ protein expression was found to be downregulated, while p‑Akt, p‑mTOR and p‑P70S6K protein expression were observed to be upregulated by ulinastatin. In addition, cell vitality was found to increase and LDH was observed to decrease in the ulinastatin group compared with the HR group in vitro. Furthermore, rapamycin was found to attenuate the myocardial protective effect that is induced by ulinastatin. In vivo, ulinastatin was found to downregulate LC3‑Ⅱ protein expression, and reduce myocardium infarct size and LDH serum levels. These findings indicate that ulinastatin exhibits a myocardial protective effect against IR injury by regulating autophagy through mTOR activation.

  10. Dose-dependent effects of mTOR inhibition on weight and mitochondrial disease in mice

    PubMed Central

    Johnson, Simon C.; Yanos, Melana E.; Bitto, Alessandro; Castanza, Anthony; Gagnidze, Arni; Gonzalez, Brenda; Gupta, Kanav; Hui, Jessica; Jarvie, Conner; Johnson, Brittany M.; Letexier, Nicolas; McCanta, Lanny; Sangesland, Maya; Tamis, Oliver; Uhde, Lauren; Van Den Ende, Alex; Rabinovitch, Peter S.; Suh, Yousin; Kaeberlein, Matt

    2015-01-01

    Rapamycin extends lifespan and attenuates age-related pathologies in mice when administered through diet at 14 parts per million (PPM). Recently, we reported that daily intraperitoneal injection of rapamycin at 8 mg/kg attenuates mitochondrial disease symptoms and progression in the Ndufs4 knockout mouse model of Leigh Syndrome. Although rapamycin is a widely used pharmaceutical agent dosage has not been rigorously examined and no dose-response profile has been established. Given these observations we sought to determine if increased doses of oral rapamycin would result in more robust impact on mTOR driven parameters. To test this hypothesis, we compared the effects of dietary rapamycin at doses ranging from 14 to 378 PPM on developmental weight in control and Ndufs4 knockout mice and on health and survival in the Ndufs4 knockout model. High dose rapamycin was well tolerated, dramatically reduced weight gain during development, and overcame gender differences. The highest oral dose, approximately 27-times the dose shown to extend murine lifespan, increased survival in Ndufs4 knockout mice similarly to daily rapamycin injection without observable adverse effects. These findings have broad implications for the effective use of rapamycin in murine studies and for the translational potential of rapamycin in the treatment of mitochondrial disease. This data, further supported by a comparison of available literature, suggests that 14 PPM dietary rapamycin is a sub-optimal dose for targeting mTOR systemically in mice. Our findings suggest that the role of mTOR in mammalian biology may be broadly underestimated when determined through treatment with rapamycin at commonly used doses. PMID:26257774

  11. Bridges between mitochondrial oxidative stress, ER stress and mTOR signaling in pancreatic β cells.

    PubMed

    Wang, Jing; Yang, Xin; Zhang, Jingjing

    2016-08-01

    Pancreatic β cell dysfunction, i.e., failure to provide insulin in concentrations sufficient to control blood sugar, is central to the etiology of all types of diabetes. Current evidence implicates mitochondrial oxidative stress and endoplasmic reticulum (ER) stress in pancreatic β cell loss and impaired insulin secretion. Oxidative and ER stress are interconnected so that misfolded proteins induce reactive oxygen species (ROS) production; likewise, oxidative stress disturbs the ER redox state thereby disrupting correct disulfide bond formation and proper protein folding. mTOR signaling regulates many metabolic processes including protein synthesis, cell growth, survival and proliferation. Oxidative stress inhibits mTORC1, which is considered an important suppressor of mitochondrial oxidative stress in β cells, and ultimately, controls cell survival. The interplay between ER stress and mTORC1 is complicated, since the unfolded protein response (UPR) activation can occur upstream or downstream of mTORC1. Persistent activation of mTORC1 initiates protein synthesis and UPR activation, while in the later phase induces ER stress. Chronic activation of ER stress inhibits Akt/mTORC1 pathway, while under particular settings, acute activation of UPR activates Akt-mTOR signaling. Thus, modulating mitochondrial oxidative stress and ER stress via mTOR signaling may be an approach that will effectively suppress obesity- or glucolipotoxicity-induced metabolic disorders such as insulin resistance and type 2 diabetes mellitus (T2DM). In this review, we focus on the regulations between mTOR signaling and mitochondrial oxidative or ER stress in pancreatic β cells.

  12. Leucine minimizes denervation-induced skeletal muscle atrophy of rats through akt/mtor signaling pathways

    PubMed Central

    Ribeiro, Carolina B.; Christofoletti, Daiane C.; Pezolato, Vitor A.; de Cássia Marqueti Durigan, Rita; Prestes, Jonato; Tibana, Ramires A.; Pereira, Elaine C. L.; de Sousa Neto, Ivo V.; Durigan, João L. Q.; da Silva, Carlos A.

    2015-01-01

    The aim of the present study was to evaluate the effect of leucine treatment (0.30 mM) on muscle weight and signaling of myoproteins related to synthesis and degradation pathways of soleus muscle following seven days of complete sciatic nerve lesion. Wistar rats (n = 24) of 3–4 months of age (192 ± 23 g) were used. The animals were randomly distributed into four experimental groups (n = 6/group): control, treated with leucine (L), denervated (D) and denervated treated with leucine (DL). Dependent measures were proteins levels of AKT, AMPK, mTOR, and ACC performed by Western blot. Leucine induced a reduction in the phosphorylation of AMPK (p < 0.05) by 16% in the L and by 68% in the DL groups as compared with control group. Denervation increased AMPK by 24% in the D group as compared with the control group (p < 0.05). AKT was also modulated by denervation and leucine treatment, highlighted by the elevation of AKT phosphorylation in the D (65%), L (98%) and DL (146%) groups as compared with the control group (p < 0.05). AKT phosphorylation was 49% higher in the D group as compared with the DL group. Furthermore, denervation decreased mTOR phosphorylation by 29% in the D group as compared with the control group. However, leucine treatment induced an increase of 49% in the phosphorylation of mTOR in the L group as compared with the control group, and an increase of 154% in the DL as compared with the D group (p < 0.05). ACC phosphorylation was 20% greater in the D group than the control group. Furthermore, ACC in the soleus was 22% lower in the in the L group and 50% lower in the DL group than the respective control group (p < 0.05). In conclusion, leucine treatment minimized the deleterious effects of denervation on rat soleus muscle by increasing anabolic (AKT and mTOR) and decreasing catabolic (AMPK) pathways. These results may be interesting for muscle recovery following acute denervation, which may contribute to musculoskeletal rehabilitation after denervation

  13. Genetic variants in the mTOR pathway and breast cancer risk in African American women.

    PubMed

    Cheng, Ting-Yuan David; Ambrosone, Christine B; Hong, Chi-Chen; Lunetta, Kathryn L; Liu, Song; Hu, Qiang; Yao, Song; Sucheston-Campbell, Lara; Bandera, Elisa V; Ruiz-Narváez, Edward A; Haddad, Stephen; Troester, Melissa A; Haiman, Christopher A; Bensen, Jeannette T; Olshan, Andrew F; Palmer, Julie R; Rosenberg, Lynn

    2016-01-01

    The phosphatidylinositol 3-kinase-AKT-mammalian target of rapamycin (mTOR) pathway has been implicated in breast carcinogenesis. However, there has been no large-scale investigation of genetic variants in the mTOR pathway and breast cancer risk. We examined 28847 single-nucleotide polymorphisms (SNPs) in 61 mTOR pathway genes in the African American Breast Cancer Epidemiology and Risk consortium of 3663 cases [1983 estrogen receptor-positive (ER+) and 1098 ER-negative (ER-)] and 4687 controls. Gene-level analyses were conducted using the adaptive rank truncated product (ARTP) test for 10773 SNPs that were not highly correlated (r (2) < 0.8), and SNP-level analyses were conducted with logistic regression. Among genes that were prioritized (nominal P < 0.05, ARTP tests), associations were observed for intronic SNPs TSC2 rs181088346 [odds ratio (OR) of each copy of variant allele = 0.77, 95% confidence interval (CI) = 0.65-0.88 for all breast cancer] and BRAF rs114729114 (OR = 1.53, 95% CI = 1.24-1.91 for all breast cancer and OR = 2.03, 95% CI = 1.50-2.76 for ER- tumors). For ER- tumors, intronic SNPs PGF rs11542848 (OR = 1.38, 95% CI = 1.15-1.66) and rs61759375 (OR = 1.34, 95% CI = 1.14-1.57) and MAPK3 rs78564187 (OR = 1.26, 95% CI = 1.11-1.43) were associated with increased risk. These SNPs were significant at a gene-wide level (Bonferroni-corrected P < 0.05). The variant allele of RPS6KB2 rs35363135, a synonymous coding SNP, was more likely to be observed in ER- than ER+ tumors (OR = 1.18, 95% CI = 1.05-1.31, gene-wide Bonferroni-corrected P = 0.06). In conclusion, specific mTOR pathway genes are potentially important to breast cancer risk and to the ER negativity in African American women. PMID:26577839

  14. Radiosynthesis of [18F]ATPFU: a potential PET ligand for mTOR.

    PubMed

    Majo, Vattoly J; Simpson, Norman R; Prabhakaran, Jaya; Mann, J John; Kumar, J S Dileep

    2014-11-01

    Mammalian target of rapamycin (mTOR) plays a pivotal role in many aspects of cellular proliferation, and recent evidence suggests that an altered mTOR signaling pathway plays a central role in the pathogenesis of aging, tumor progression, neuropsychiatric, and major depressive disorder. Availability of a mTOR-specific PET tracer will facilitate monitoring early response to treatment with mTOR inhibitors that are under clinical development. Towards this we have developed the radiosynthesis of [(18)F]1-(4-(4-(8-oxa-3-azabicyclo[3.2.1]octan-3-yl)-1-(2,2,2-trifluoroethyl)-1H-pyrazolo[3,4-d]pyrimidin-6-yl)phenyl)-3-(2-fluoroethyl)urea [(18)F]ATPFU ([(18)F]1) as an mTOR PET ligand. Synthesis of reference 1 and the precursor for radiolabeling, 4-(4-8-oxa-3-azabicyclo[3.2.1]-octan-3yl)-1-(2,2,2-trifluoroethyl)-1H-pyrazolo[3,4-d]pyrimidin-6yl)aniline (10), were achieved from beta-chloroaldehyde 3 in 4 and 5 steps, respectively, with an overall yield of 25-28%. [(18)F]Fluoroethylamine was prepared by heating N-[2-(toluene-4-sulfonyloxy)ethyl]phthalimide with [(18)F]fluoride ion in acetonitrile. [(18)F]1 was obtained by slow distillation under argon of [(18) F]FCH2CH2NH2 into amine 10 that was pre-treated with triphosgene at 0-5 °C. The total time required for the two-step radiosynthesis including semi-preparative HPLC purification was 90 min, and the overall radiochemical yield of [(18)F]1 for the process was 15 ± 5% based on [(18)F]fluoride ion (decay corrected). At the end of synthesis (EOS), the specific activity was 37-74 GBq/µmol (N = 6). PMID:25359578

  15. Inhibition of mTOR by Rapamycin Results in Auditory Hair Cell Damage and Decreased Spiral Ganglion Neuron Outgrowth and Neurite Formation In Vitro.

    PubMed

    Leitmeyer, Katharina; Glutz, Andrea; Radojevic, Vesna; Setz, Cristian; Huerzeler, Nathan; Bumann, Helen; Bodmer, Daniel; Brand, Yves

    2015-01-01

    Rapamycin is an antifungal agent with immunosuppressive properties. Rapamycin inhibits the mammalian target of rapamycin (mTOR) by blocking the mTOR complex 1 (mTORC1). mTOR is an atypical serine/threonine protein kinase, which controls cell growth, cell proliferation, and cell metabolism. However, less is known about the mTOR pathway in the inner ear. First, we evaluated whether or not the two mTOR complexes (mTORC1 and mTORC2, resp.) are present in the mammalian cochlea. Next, tissue explants of 5-day-old rats were treated with increasing concentrations of rapamycin to explore the effects of rapamycin on auditory hair cells and spiral ganglion neurons. Auditory hair cell survival, spiral ganglion neuron number, length of neurites, and neuronal survival were analyzed in vitro. Our data indicates that both mTOR complexes are expressed in the mammalian cochlea. We observed that inhibition of mTOR by rapamycin results in a dose dependent damage of auditory hair cells. Moreover, spiral ganglion neurite number and length of neurites were significantly decreased in all concentrations used compared to control in a dose dependent manner. Our data indicate that the mTOR may play a role in the survival of hair cells and modulates spiral ganglion neuronal outgrowth and neurite formation.

  16. microRNA-mediated regulation of mTOR complex components facilitates discrimination between activation and anergy in CD4 T cells

    PubMed Central

    Marcais, Antoine; Blevins, Rory; Graumann, Johannes; Feytout, Amelie; Dharmalingam, Gopuraja; Carroll, Thomas; Amado, Inês F.; Bruno, Ludovica; Lee, Keunwook; Walzer, Thierry; Mann, Matthias; Freitas, Antonio A.; Boothby, Mark; Fisher, Amanda G.

    2014-01-01

    T cell receptor (TCR) signals can elicit full activation with acquisition of effector functions or a state of anergy. Here, we ask whether microRNAs affect the interpretation of TCR signaling. We find that Dicer-deficient CD4 T cells fail to correctly discriminate between activating and anergy-inducing stimuli and produce IL-2 in the absence of co-stimulation. Excess IL-2 production by Dicer-deficient CD4 T cells was sufficient to override anergy induction in WT T cells and to restore inducible Foxp3 expression in Il2-deficient CD4 T cells. Phosphorylation of Akt on S473 and of S6 ribosomal protein was increased and sustained in Dicer-deficient CD4 T cells, indicating elevated mTOR activity. The mTOR components Mtor and Rictor were posttranscriptionally deregulated, and the microRNAs Let-7 and miR-16 targeted the Mtor and Rictor mRNAs. Remarkably, returning Mtor and Rictor to normal levels by deleting one allele of Mtor and one allele of Rictor was sufficient to reduce Akt S473 phosphorylation and to reduce co-stimulation–independent IL-2 production in Dicer-deficient CD4 T cells. These results show that microRNAs regulate the expression of mTOR components in T cells, and that this regulation is critical for the modulation of mTOR activity. Hence, microRNAs contribute to the discrimination between T cell activation and anergy. PMID:25311506

  17. Chronic leucine supplementation of a low protein diet increases protein synthesis in skeletal muscle and visceral tissues of neonatal pigs through mTOR signaling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leucine acutely stimulates protein synthesis by activating the mammalian target of rapamycin (mTOR) signaling pathway. We hypothesized that leucine supplementation of a low protein diet will enhance protein synthesis and mTOR signaling in the neonate for prolonged periods. Fasted 5-d-old pigs (n=6–8...

  18. Murine dendritic cell rapamycin-resistant and rictor-independent mTOR controls IL-10, B7-H1, and regulatory T-cell induction

    PubMed Central

    Rosborough, Brian R.; Raïch-Regué, Dàlia; Matta, Benjamin M.; Lee, Keunwook; Gan, Boyi; DePinho, Ronald A.; Hackstein, Holger; Boothby, Mark

    2013-01-01

    Mammalian target of rapamycin (mTOR) is an important, yet poorly understood integrative kinase that regulates immune cell function. mTOR functions in 2 independent complexes: mTOR complex (mTORC) 1 and 2. The immunosuppressant rapamycin (RAPA) inhibits mTORC1 but not mTORC2 and causes a paradoxical reduction in anti-inflammatory interleukin (IL) 10 and B7-homolog 1 (B7-H1) expression by dendritic cells (DCs). Using catalytic mTOR inhibitors and DCs lacking mTORC2, we show that restraint of signal transducer and activator of transcription 3–mediated IL-10 and B7-H1 expression during DC maturation involves a RAPA-insensitive and mTORC2-independent mTOR mechanism. Relatedly, catalytic mTOR inhibition promotes B7-H1–dependent and IL-1β–dependent DC induction of regulatory T cells (Tregs). Thus, we define an immunoregulatory pathway in which RAPA-sensitive mTORC1 in DCs promotes effector T-cell expansion and RAPA-insensitive mTORC1 restrains Treg induction. These findings identify the first known RAPA-insensitive mTOR pathway that is not mediated solely by mTORC2 and have implications for the use of catalytic mTOR inhibitors in inflammatory disease settings. PMID:23444404

  19. Subependymal giant cell astrocytoma: a lesion with activated mTOR pathway and constant expression of glutamine synthetase.

    PubMed

    Buccoliero, Anna Maria; Caporalini, Chiara; Giordano, Flavio; Mussa, Federico; Scagnet, Mirko; Moscardi, Selene; Baroni, Gianna; Genitori, Lorenzo; Taddei, Gian Luigi

    2016-01-01

    Subependymal giant-cell astrocytoma (SEGA) is a rare tumor associated with tuberous sclerosis complex (TSC). TSC mainly involves the central nervous system (CNS) where SEGA, subependymal nodules, and cortical tubers may be present. First studies suggested the astrocytic nature of SEGA while successive studies demonstrated the mixed glio-neuronal nature. There are similarities between TSC-associated CNS lesions and type IIb focal cortical dysplasia (FCD). In all these pathologies, mammalian target of rapamycin (mTOR) pathway activation has been demonstrated. Recent data evidenced that balloon cells in FCD IIb express glutamine synthetase (GS). GS is involved in the clearance of glutamate. Cells expressing GS might exert an antiepileptic role. We evaluated by immunohistochemistry the glial fibrillary acidic protein (GFAP), neurofilaments (NF), and GS expression and the mTOR status (mTOR and phosphorylated ribosomal protein S6) in 16 SEGAs and 2 cortical tubers. Our purpose was to emphasize the mixed nature of SEGA and to further investigate the similarities between TSC-related CNS lesions (in particular SEGA) and FCD IIb. We confirm the glio-neuronal nature and the common activation of the mTOR pathway in SEGAs. In addition, we report for the first time that these tumors, analogously to FCD IIb, commonly express GS. Notably, the expression of mTOR, phosphorylated ribosomal protein S6, and GS was restricted to gemistocytic-like GFAP-negative cells. GS expression and mTOR pathway activation were also documented in cortical tubers. Further studies are necessary to understand the significance of GS expression in SEGAs as well as in cortical tubers. PMID:27390104

  20. PPARγ deficiency results in severe, accelerated osteoarthritis associated with aberrant mTOR signalling in the articular cartilage

    PubMed Central

    Vasheghani, Faezeh; Zhang, Yue; Li, Ying-Hua; Blati, Meryem; Fahmi, Hassan; Lussier, Bertrand; Roughley, Peter; Lagares, David; Endisha, Helal; Saffar, Bahareh; Lajeunesse, Daniel; Marshall, Wayne K; Rampersaud, Y Raja; Mahomed, Nizar N; Gandhi, Rajiv; Pelletier, Jean-Pierre; Martel-Pelletier, Johanne; Kapoor, Mohit

    2015-01-01

    Objectives We have previously shown that peroxisome proliferator-activated receptor gamma (PPARγ), a transcription factor, is essential for the normal growth and development of cartilage. In the present study, we created inducible cartilage-specific PPARγ knockout (KO) mice and subjected these mice to the destabilisation of medial meniscus (DMM) model of osteoarthritis (OA) to elucidate the specific in vivo role of PPARγ in OA pathophysiology. We further investigated the downstream PPARγ signalling pathway responsible for maintaining cartilage homeostasis. Methods Inducible cartilage-specific PPARγ KO mice were generated and subjected to DMM model of OA. We also created inducible cartilage-specific PPARγ/mammalian target for rapamycin (mTOR) double KO mice to dissect the PPARγ signalling pathway in OA. Results Compared with control mice, PPARγ KO mice exhibit accelerated OA phenotype with increased cartilage degradation, chondrocyte apoptosis, and the overproduction of OA inflammatory/catabolic factors associated with the increased expression of mTOR and the suppression of key autophagy markers. In vitro rescue experiments using PPARγ expression vector reduced mTOR expression, increased expression of autophagy markers and reduced the expression of OA inflammatory/catabolic factors, thus reversing the phenotype of PPARγ KO mice chondrocytes. To dissect the in vivo role of mTOR pathway in PPARγ signalling, we created and subjected PPARγ-mTOR double KO mice to the OA model to see if the genetic deletion of mTOR in PPARγ KO mice (double KO) can rescue the accelerated OA phenotype observed in PPARγ KO mice. Indeed, PPARγ-mTOR double KO mice exhibit significant protection/reversal from OA phenotype. Significance PPARγ maintains articular cartilage homeostasis, in part, by regulating mTOR pathway. PMID:25573665

  1. Subependymal giant cell astrocytoma: a lesion with activated mTOR pathway and constant expression of glutamine synthetase.

    PubMed

    Buccoliero, Anna Maria; Caporalini, Chiara; Giordano, Flavio; Mussa, Federico; Scagnet, Mirko; Moscardi, Selene; Baroni, Gianna; Genitori, Lorenzo; Taddei, Gian Luigi

    2016-01-01

    Subependymal giant-cell astrocytoma (SEGA) is a rare tumor associated with tuberous sclerosis complex (TSC). TSC mainly involves the central nervous system (CNS) where SEGA, subependymal nodules, and cortical tubers may be present. First studies suggested the astrocytic nature of SEGA while successive studies demonstrated the mixed glio-neuronal nature. There are similarities between TSC-associated CNS lesions and type IIb focal cortical dysplasia (FCD). In all these pathologies, mammalian target of rapamycin (mTOR) pathway activation has been demonstrated. Recent data evidenced that balloon cells in FCD IIb express glutamine synthetase (GS). GS is involved in the clearance of glutamate. Cells expressing GS might exert an antiepileptic role. We evaluated by immunohistochemistry the glial fibrillary acidic protein (GFAP), neurofilaments (NF), and GS expression and the mTOR status (mTOR and phosphorylated ribosomal protein S6) in 16 SEGAs and 2 cortical tubers. Our purpose was to emphasize the mixed nature of SEGA and to further investigate the similarities between TSC-related CNS lesions (in particular SEGA) and FCD IIb. We confirm the glio-neuronal nature and the common activation of the mTOR pathway in SEGAs. In addition, we report for the first time that these tumors, analogously to FCD IIb, commonly express GS. Notably, the expression of mTOR, phosphorylated ribosomal protein S6, and GS was restricted to gemistocytic-like GFAP-negative cells. GS expression and mTOR pathway activation were also documented in cortical tubers. Further studies are necessary to understand the significance of GS expression in SEGAs as well as in cortical tubers.

  2. Caloric restriction protects against electrical kindling of the amygdala by inhibiting the mTOR signaling pathway

    PubMed Central

    Phillips-Farfán, Bryan V.; Rubio Osornio, María del Carmen; Custodio Ramírez, Verónica; Paz Tres, Carlos; Carvajal Aguilera, Karla G.

    2015-01-01

    Caloric restriction (CR) has been shown to possess antiepileptic properties; however its mechanism of action is poorly understood. CR might inhibit the activity of the mammalian or mechanistic target of rapamycin (mTOR) signaling cascade, which seems to participate crucially in the generation of epilepsy. Thus, we investigated the effect of CR on the mTOR pathway and whether CR modified epilepsy generation due to electrical amygdala kindling. The former was studied by analyzing the phosphorylation of adenosine monophosphate-activated protein kinase, protein kinase B and the ribosomal protein S6. The mTOR cascade is regulated by energy and by insulin levels, both of which may be changed by CR; thus we investigated if CR altered the levels of energy substrates in the blood or the level of insulin in plasma. Finally, we studied if CR modified the expression of genes that encode proteins participating in the mTOR pathway. CR increased the after-discharge threshold and tended to reduce the after-discharge duration, indicating an anti-convulsive action. CR diminished the phosphorylation of protein kinase B and ribosomal protein S6, suggesting an inhibition of the mTOR cascade. However, CR did not change glucose, β-hydroxybutyrate or insulin levels; thus the effects of CR were independent from them. Interestingly, CR also did not modify the expression of any investigated gene. The results suggest that the anti-epileptic effect of CR may be partly due to inhibition of the mTOR pathway. PMID:25814935

  3. The mechanism of mTOR (mammalian target of rapamycin) in a mouse model of polycystic ovary syndrome (PCOS)

    PubMed Central

    2012-01-01

    Polycystic ovary syndrome (PCOS) is a common and complex endocrine disorder affecting 5-10% of women in reproductive age that is characterized by hyperandrogenism, oligo- or anovulation and infertility. However the pathophysiology of PCOS still remains unknown. The mammalian target of rapamycin (mTOR) is a central component that regulates various processes including cell growth, proliferation, metabolism, and angiogenesis. mTOR signaling cascade has recently been examined in ovarian follicles where it regulates granulosa cell proliferation and differentiation. mTOR functions as two complexes, mTOR complex 1 and 2. Therefore, we hypothesized that mTORC1 and/or 2 may have important role in proliferation of theca and granulosa cells in PCOS. In the present study, we sought to determine the mTOR signaling pathway in PCOS mouse ovary. We designed 3 groups: Control (C, no treatment), PCOS (P, The injection of DHEA (6 mg/100 g BW in 0.1 ml of sesame oil) (s.c) for 20 consecutive days), Vehicle (V, daily (s.c) sesame oil alone injection). Our results showed that mTORC1 and mTORC2-mediated signaling may play a role in PCOS mouse ovary. These findings provide evidence that mTORC1 and mTORC2 may have responsibility in increased ovarian follicular cell proliferation and growth in PCOS. Consequently, these results suggest that the mTOR signaling pathways (mTORC1 and mTORC 2) may create new clinical strategies to optimize developmental competence of PCOS should target correction of the entire follicle growth, oocyte development process and anovulatory infertility in PCOS. PMID:23185989

  4. The PI 3-kinase and mTOR signaling pathways are important modulators of epithelial tubule formation.

    PubMed

    Walid, Shereaf; Eisen, Randi; Ratcliffe, Don R; Dai, Kezhi; Hussain, M Mahmood; Ojakian, George K

    2008-08-01

    Using MDCK cells as a model system, evidence is presented demonstrating that the signaling pathways mammalian target of rapamycin (mTOR) and phosphoinositide 3-kinase (PI 3-kinase) play important roles in the regulation of epithelial tubule formation. Incubation of cells with collagen gel overlays induced early (4-8 h) reorganization of cells (epithelial remodeling) into three-dimensional multicellular tubular structures over 24 h. An MDCK cell line stably expressing the PH domain of Akt, a PI 3-kinase downstream effector, coupled to green fluorescent protein (GFP-Akt-PH) was used to determine the distribution of phosphatidyl inositol-3,4,5-P(3) (PIP(3)), a product of PI 3-kinase. GFP-Akt-PH was associated with lateral membranes in control cells. After incubation with collagen gel overlays, GFP-Akt-PH redistributed into the lamellipodia of migrating cells suggesting that PIP(3) plays a role in epithelial remodeling. Using the small molecule inhibitor LY-294002 that inhibits both mTOR and PI 3-kinase, we demonstrated that kinase activity was required for epithelial remodeling, disruption of cell junctions and subsequent modulation of tubule formation. Since the mTOR signaling pathway is downstream of PI 3-kinase, the effects of rapamycin, a specific mTOR inhibitor, on tubule formation were assessed. Rapamycin did not affect epithelial remodeling or GFP-Akt-PH redistribution but inhibited elongated tubule formation that occurred later (24 h) in morphogenesis. These results were further supported by using RNA interference to down-regulate mTOR and inhibit tubule formation. Our studies demonstrate that PI 3-kinase regulates early epithelial remodeling stages while mTOR modulates latter stages of tubule development. PMID:18366086

  5. A single nucleotide polymorphism in the MTOR gene is associated with recurrent spontaneous abortion in the Chinese female population.

    PubMed

    Xiang, Huifen; Liu, Shengnan; Zong, Chen; Li, Zelian; Liu, Yunyun; Ma, Xu; Cao, Yunxia

    2015-01-01

    Recurrent spontaneous abortion (RSA) is a multi-factor disease. The mammalian target of the the rapamycin (MTOR) gene has been reported to be involved in mouse embryo development and regulates the proliferation of embryonic stem cells. Our study explored the relationship between the single nucleotide polymorphism (SNP) rs17027478 in the promoter region of MTOR gene and the development of RSA. A total of 306 patients with RSA and 127 healthy females as the controls were recruited in the case-control study. The predesigned TaqMan SNP Genotyping Assay was adopted to analyze the association between rs17027478 and the development of RSA. Quantitative real-time reverse transcription polymerase chain reaction and luciferase reporter assays were conducted to analyze the function of the variant. It was found that a significant association exists between the variant and the risk of RSA among the patients who experienced no less than three spontaneous abortions (p = 0.043). However, the significant difference disappeared among the total samples (p = 0.524). Furthermore, we observed lower MTOR mRNA levels in the blood of RSA patients compared with healthy females (p = 0.020). The luciferase reporter assay showed that the rs17027478A allele significantly reduced the luciferase activity (p = 0.029). The results demonstrated that the variant rs17027478 in the promoter region of MTOR might be a good candidate responsible for the pathogenesis of RSA. Abbreviations RSA recurrent spontaneous abortion MTOR mammalian target of rapamycin SNP single nucleotide polymorphism qRT-PCR quantitative real-time polymerase chain reaction URSA unexplained recurrent spontaneous abortion mTORC1 mTOR complex 1 ESC embryonic stem cells HKE-293 human embryonic kidney 293 cells HWE Hardy-Weinberg equilibrium ANOVA one-way analysis of variance.

  6. Wide spectrum of developmental brain disorders from megalencephaly to focal cortical dysplasia and pigmentary mosaicism caused by mutations of MTOR

    PubMed Central

    Solovieff, Nadia; Goold, Carleton; Jansen, Laura A.; Menon, Suchithra; Timms, Andrew E.; Conti, Valerio; Biag, Jonathan D.; Adams, Carissa; Boyle, Evan August; Collins, Sarah; Ishak, Gisele; Poliachik, Sandra; Girisha, Katta M.; Yeung, Kit San; Chung, Brian Hon Yin; Rahikkala, Elisa; Gunter, Sonya A.; McDaniel, Sharon S.; Macmurdo, Colleen Forsyth; Bernstein, Jonathan A.; Martin, Beth; Leary, Rebecca; Mahan, Scott; Liu, Shanming; Weaver, Molly; Doerschner, Michael; Jhangiani, Shalini; Muzny, Donna M.; Boerwinkle, Eric; Gibbs, Richard A.; Lupski, James R.; Shendure, Jay; Saneto, Russell P.; Novotny, Edward J.; Wilson, Christopher J.; Sellers, William R.; Morrissey, Michael; Hevner, Robert F.; Ojemann, Jeffrey G.; Guerrini, Renzo; Murphy, Leon O.; Winckler, Wendy; Dobyns, William B.

    2016-01-01

    Importance Focal cortical dysplasia (FCD), hemimegalencephaly (HMEG) and megalencephaly constitute a spectrum of malformations of cortical development with shared neuropathologic features. Collectively, these disorders are associated with significant childhood morbidity and mortality. FCD, in particular, represents the most frequent cause of intractable focal epilepsy in children. Objective To identify the underlying molecular etiology of FCD, HMEG, and diffuse megalencephaly. Design, Setting and Participants We performed whole exome sequencing (WES) on eight children with FCD or HMEG using standard depth (~50-60X) sequencing in peripheral samples (blood, saliva or skin) from the affected child and their parents, and deep (~150-180X) sequencing in affected brain tissue. We used both targeted sequencing and WES to screen a cohort of 93 children with molecularly unexplained diffuse or focal brain overgrowth (42 with FCD-HMEG, and 51 with diffuse megalencephaly). Histopathological and functional assays of PI3K-AKT-MTOR pathway activity in resected brain tissue and cultured neurons were performed to validate mutations. Main Outcomes and Measures Whole exome sequencing and targeted sequencing identified variants associated with this spectrum of developmental brain disorders. Results We identified low-level mosaic mutations of MTOR in brain tissue in four children with FCD type 2a with alternative allele fractions ranging from 0.012–0.086. We also identified intermediate level mosaic mutation of MTOR (p.Thr1977Ile) in three unrelated children with diffuse megalencephaly and pigmentary mosaicism in skin that resembles hypomelanosis of Ito. Finally, we identified a constitutional de novo mutation of MTOR (p.Glu1799Lys) in three unrelated children with diffuse megalencephaly and intellectual disability. Molecular and functional analysis in two children with FCD type 2a from whom multiple affected brain tissue samples were available revealed a gradient of alternate allele

  7. Mapping similarities in mTOR pathway perturbations in mouse lupus nephritis models and human lupus nephritis

    PubMed Central

    Reddy, Padmalatha S; Legault, Holly M; Sypek, Joseph P; Collins, Mark J; Goad, Elizabeth; Goldman, Samuel J; Liu, Wei; Murray, Stuart; Dorner, Andrew J; O'Toole, Margot

    2008-01-01

    Introduction Treatment with sirolimus, a mammalian target of rapamycin (mTOR) inhibitor, has been shown to be efficacious in the MRL/lpr and NZB × NZW F1 mouse models of lupus nephritis, indicating a critical role for the mTOR pathway in both models. This type of demonstration of efficacy in animal models is usually a pre-requisite for advancement into clinical development. However, efficacy in an animal model often has not translated to the desired activity in the clinic. Therefore, a more profound understanding of the mechanistic similarities and differences between various animal models and human diseases is highly desirable. Methods Transcriptional profiling was performed on kidneys from mice with lupus nephritis; from mice who had efficacious drug treatment; and from mice before they developed nephritis. Analysis of variance with false discovery rate adjusted to p < 0.05 and an average fold change of two or more was used to identify transcripts significantly associated with disease and response to therapy. Pathway analyses (using various bioinformatics tools) were carried out to understand the basis for drug efficacy in the mouse model. The relevance in human lupus of the pathways identified in the mouse model was explored using information from several databases derived from the published literature. Results We identified a set of nephritis-associated genes in mouse kidney. Expression of the majority of these returned to asymptomatic levels on sirolimus treatment, confirming the correlation between expression levels and symptoms of nephritis. Network analysis showed that many of these nephritis genes are known to interact with the mTOR pathway. This led us to ask what human diseases are linked to the mTOR pathway. We constructed the mTOR pathway interactome consisting of proteins that interact with members of the mTOR pathway and identified a strong association between mTOR pathway genes and genes reported in the literature as being involved in human lupus

  8. Mammalian target of rapamycin (mTOR) inhibition reduces cerebral vasospasm following a subarachnoid hemorrhage injury in canines.

    PubMed

    Zhang, Weiguang; Khatibi, Nikan H; Yamaguchi-Okada, Mitsuo; Yan, Junhao; Chen, Chunhua; Hu, Qin; Meng, Haiwei; Han, Hongbin; Liu, Shuwei; Zhou, Changman

    2012-02-01

    Mammalian target of rapamycin (mTOR) pathway is a serine/threonine protein kinase that plays a vital role in regulating growth, proliferation, survival, and protein synthesis among cells. In the present study, we investigated the role of the mTOR pathway following subarachnoid hemorrhage brain injury--specifically investigating its ability to mediate the activation of cerebral vasospasm. Additionally, we investigated whether key signaling pathway molecules such as the mTOR, P70S6K1, and 4E-BP1 play a role in the process. Thirty dogs were randomly divided into 5 groups: sham, SAH (subarachnoid hemorrhage), SAH+DMSO (dimethyl sulfoxide), SAH+Rapamycin and SAH+AZD8055. An established canine double-hemorrhage model of SAH was used by injecting autologous arterial blood into the cisterna magna on days 0 and 2. Angiography was performed at days 0 and 7. Clinical behavior, histology, immunohistochemistry, and Western blot of mTOR, P70S6K1, 4E-BP1 and PCNA (proliferating cell nuclear antigen) in the basilar arteries were examined. In the SAH and SAH+DMSO groups, severe angiographic vasospasm was obtained (34.3±19.8%, 38.4±10.3) compared with that in Sham (93.9±5.0%) respectively. mTOR, P70S6K1, 4E-BP1 and PCNA increased in the sample of spastic basilar arteries (p<0.05). In the SAH+RAPA and SAH+AZD8055 groups, Rapamycin and AZD8055 attenuated angiographic vasospasm (62.3±15.9% and 65.2±10.3%) while improving appetite and activity scores (p<0.05) on days 5 through 7. Rapamycin and AZD8055 significantly reduced the level and expression of mTOR, P70S6K1, 4E-BP1 and PCNA (p<0.05). In conclusion, our study suggests that the mTOR molecular signaling pathway plays a significant role in cerebral vasospasm following SAH, and that inhibition of the mTOR pathway has the potential to become an attractive strategy to treat vasospasm following SAH. PMID:22177999

  9. NRSF/REST regulates the mTOR signaling pathway in oral cancer cells.

    PubMed

    Cho, Eugene; Moon, Sung-Min; Park, Bo Ram; Kim, Do Kyung; Lee, Byung-Kwon; Kim, Chun Sung

    2015-03-01

    The neuron-restrictive silencer factor/repressor element 1-silencing transcription factor (NRSF/REST) was originally discovered as a transcriptional repressor of neuronal genes in non-neuronal cells. However, it was recently reported to be abundantly expressed in several types of aggressive cancer cells, as well as in mature neurons. In the present study, the role of NRSF/REST in the human oral squamous cell carcinoma (SCC) KB cell line was evaluated. NRSF/REST was expressed at a higher level in KB cells when compared with that in normal human oral keratinocytes (NHOKs). Knockdown of NRSF/REST by siRNA reduced cell viability only in KB cells in a time-dependent manner, and this effect was due to the activation of apoptosis components and DNA fragmentation. In addition, knockdown of NRSF/REST disrupted the mTOR signaling pathway which is a key survival factor in many types of cancer cells. For example, the phosphorylation of elF4G, elF4E and 4E-BP1 was significantly reduced in the KΒ cells upon NRSF/REST knockdown. These results imply that NRSF/REST plays an important role in the survival of oral cancer cells by regulating the mTOR signaling pathway. PMID:25524378

  10. Advances in the therapeutic use of mammalian target of rapamycin (mTOR) inhibitors in dermatology.

    PubMed

    Fogel, Alexander L; Hill, Sharleen; Teng, Joyce M C

    2015-05-01

    Significant developments in the use of mammalian target of rapamycin (mTOR) inhibitors (mTORIs) as immunosuppressant and antiproliferative agents have been made. Recent advances in the understanding of the mTOR signaling pathway and its downstream effects on tumorigenesis and vascular proliferation have broadened the clinical applications of mTORIs in many challenging disorders such as tuberous sclerosis complex, pachyonychia congenita, complex vascular anomalies, and inflammatory dermatoses. Systemic mTORI therapy has shown benefits in these areas, but is associated with significant side effects that sometimes necessitate drug holidays. To mitigate the side effects of systemic mTORIs for dermatologic applications, preliminary work to assess the potential of percutaneous therapy has been performed, and the evidence suggests that percutaneous delivery of mTORIs may allow for effective long-term therapy while avoiding systemic toxicities. Additional large placebo-controlled, double-blinded, randomized studies are needed to assess the efficacy, safety, duration, and tolerability of topical treatments. The objective of this review is to provide updated information on the novel use of mTORIs in the management of many cutaneous disorders. PMID:25769191

  11. Oncogenic mTOR signalling recruits myeloid-derived suppressor cells to promote tumour initiation.

    PubMed

    Welte, Thomas; Kim, Ik Sun; Tian, Lin; Gao, Xia; Wang, Hai; Li, June; Holdman, Xue B; Herschkowitz, Jason I; Pond, Adam; Xie, Guorui; Kurley, Sarah; Nguyen, Tuan; Liao, Lan; Dobrolecki, Lacey E; Pang, Lan; Mo, Qianxing; Edwards, Dean P; Huang, Shixia; Xin, Li; Xu, Jianming; Li, Yi; Lewis, Michael T; Wang, Tian; Westbrook, Thomas F; Rosen, Jeffrey M; Zhang, Xiang H-F

    2016-06-01

    Myeloid-derived suppressor cells (MDSCs) play critical roles in primary and metastatic cancer progression. MDSC regulation is widely variable even among patients harbouring the same type of malignancy, and the mechanisms governing such heterogeneity are largely unknown. Here, integrating human tumour genomics and syngeneic mammary tumour models, we demonstrate that mTOR signalling in cancer cells dictates a mammary tumour's ability to stimulate MDSC accumulation through regulating G-CSF. Inhibiting this pathway or its activators (for example, FGFR) impairs tumour progression, which is partially rescued by restoring MDSCs or G-CSF. Tumour-initiating cells (TICs) exhibit elevated G-CSF. MDSCs reciprocally increase TIC frequency through activating Notch in tumour cells, forming a feedforward loop. Analyses of primary breast cancers and patient-derived xenografts corroborate these mechanisms in patients. These findings establish a non-canonical oncogenic role of mTOR signalling in recruiting pro-tumorigenic MDSCs and show how defined cancer subsets may evolve to promote and depend on a distinct immune microenvironment. PMID:27183469

  12. Cyclin B Translation Depends on mTOR Activity after Fertilization in Sea Urchin Embryos.

    PubMed

    Chassé, Héloïse; Mulner-Lorillon, Odile; Boulben, Sandrine; Glippa, Virginie; Morales, Julia; Cormier, Patrick

    2016-01-01

    The cyclin B/CDK1 complex is a key regulator of mitotic entry. Using PP242, a specific ATP-competitive inhibitor of mTOR kinase, we provide evidence that the mTOR signalling pathway controls cyclin B mRNA translation following fertilization in Sphaerechinus granularis and Paracentrotus lividus. We show that PP242 inhibits the degradation of the cap-dependent translation repressor 4E-BP (eukaryotic initiation factor 4E-Binding Protein). PP242 inhibits global protein synthesis, delays cyclin B accumulation, cyclin B/CDK1 complex activation and consequently entry into the mitotic phase of the cell cycle triggered by fertilization. PP242 inhibits cyclin B mRNA recruitment into active polysomes triggered by fertilization. An amount of cyclin B mRNA present in active polysomes appears to be insensitive to PP242 treatment. Taken together, our results suggest that, following sea urchin egg fertilization, cyclin B mRNA translation is controlled by two independent mechanisms: a PP242-sensitive and an additional PP242-insentitive mechanism.

  13. Is mTOR Inhibitor Good Enough for Treatment All Tumors in TSC Patients?

    PubMed Central

    Habib, Samy L; Al-Obaidi, Noor Y; Nowacki, Maciej; Pietkun, Katarzyna; Zegarska, Barbara; Kloskowski, Tomasz; Zegarski, Wojciech; Drewa, Tomasz; Medina, Edward A.; Zhao, Zhenze; Liang, Sitai

    2016-01-01

    Tuberous sclerosis complex (TSC) is an autosomal dominant and multi-system genetic disorder in humans. TSC affects around 25,000 to 40,000 individuals in the United States and about 1 to 2 million individuals worldwide, with an estimated prevalence of one in 6,000 newborns. TSC occurs in all races and ethnic groups, and in both genders. TSC is caused by defects or mutations in two genes, TSC1 and TSC2. Loss of TSC1/TSC2 leads to dysregulation of mTOR, resulting in aberrant cell differentiation and development, and abnormal enlargement of cells. TSC is characterized by the development of benign and/or malignant tumors in several organs including renal/liver angiomyolipomas, facial angiofibroma, lymphangiomyomatosis, cardiac rhabdomyomas, retinal astrocytic, renal cell carcinoma, and brain subependymal giant cell astrocytomas (SEGA). In addition, TSC disease causes disabling neurologic disorders, including epilepsy, mental retardation and autism. Particularly problematic are the development of renal angiomyolipomas, which tend to be larger, bilateral, multifocal and present at a younger age compared with sporadic forms. In addition, SEGA block the flow of fluid within the brain, causing a buildup of fluid and pressure that leads to blurred vision and seizures. In the current review, we describe the pathology of TSC disease in key organs and summarize the use of mTOR inhibitors to treat tumors in TSC patients.

  14. The oncometabolite 2-hydroxyglutarate activates the mTOR signalling pathway.

    PubMed

    Carbonneau, Mélissa; M Gagné, Laurence; Lalonde, Marie-Eve; Germain, Marie-Anne; Motorina, Alena; Guiot, Marie-Christine; Secco, Blandine; Vincent, Emma E; Tumber, Anthony; Hulea, Laura; Bergeman, Jonathan; Oppermann, Udo; Jones, Russell G; Laplante, Mathieu; Topisirovic, Ivan; Petrecca, Kevin; Huot, Marc-Étienne; Mallette, Frédérick A

    2016-01-01

    The identification of cancer-associated mutations in the tricarboxylic acid (TCA) cycle enzymes isocitrate dehydrogenases 1 and 2 (IDH1/2) highlights the prevailing notion that aberrant metabolic function can contribute to carcinogenesis. IDH1/2 normally catalyse the oxidative decarboxylation of isocitrate into α-ketoglutarate (αKG). In gliomas and acute myeloid leukaemias, IDH1/2 mutations confer gain-of-function leading to production of the oncometabolite R-2-hydroxyglutarate (2HG) from αKG. Here we show that generation of 2HG by mutated IDH1/2 leads to the activation of mTOR by inhibiting KDM4A, an αKG-dependent enzyme of the Jumonji family of lysine demethylases. Furthermore, KDM4A associates with the DEP domain-containing mTOR-interacting protein (DEPTOR), a negative regulator of mTORC1/2. Depletion of KDM4A decreases DEPTOR protein stability. Our results provide an additional molecular mechanism for the oncogenic activity of mutant IDH1/2 by revealing an unprecedented link between TCA cycle defects and positive modulation of mTOR function downstream of the canonical PI3K/AKT/TSC1-2 pathway. PMID:27624942

  15. YB-1 Synthesis Is Regulated by mTOR Signaling Pathway

    PubMed Central

    Lyabin, Dmitry N.; Eliseeva, Irina A.; Ovchinnikov, Lev P.

    2012-01-01

    YB-1 is a eukaryotic protein with numerous intra- and extracellular functions based on its ability to interact with RNA, DNA, and many proteins. In spite of achievements in studying its functions, regulation of YB-1 synthesis in the cell remains poorly understood. In the current study Western and Northern blotting were used to determine the amounts of YB-1 and YB-1 mRNA in rabbit organs and several cell lines. As found, in the majority of studied eukaryotic cells a considerable proportion of YB-1 mRNA was stored in free mRNPs, i.e., was poorly translated. Also, we demonstrated that YB-1 synthesis depended on conditions that determined the rate of cell division. Specific suppression of YB-1 synthesis resulted from inhibition of the mTOR signaling pathway with inhibitor PP242, but not rapamycin. Experiments on reporter constructs showed that dependence of YB-1 mRNA translation on activity of the mTOR signaling pathway was dictated by 5′ untranslated regions of this mRNA, irrelatively of the TOP-like sequences at the beginning of 5′ UTR. PMID:23285076

  16. The oncometabolite 2-hydroxyglutarate activates the mTOR signalling pathway

    PubMed Central

    Carbonneau, Mélissa; M. Gagné, Laurence; Lalonde, Marie-Eve; Germain, Marie-Anne; Motorina, Alena; Guiot, Marie-Christine; Secco, Blandine; Vincent, Emma E.; Tumber, Anthony; Hulea, Laura; Bergeman, Jonathan; Oppermann, Udo; Jones, Russell G.; Laplante, Mathieu; Topisirovic, Ivan; Petrecca, Kevin; Huot, Marc-Étienne; Mallette, Frédérick A.

    2016-01-01

    The identification of cancer-associated mutations in the tricarboxylic acid (TCA) cycle enzymes isocitrate dehydrogenases 1 and 2 (IDH1/2) highlights the prevailing notion that aberrant metabolic function can contribute to carcinogenesis. IDH1/2 normally catalyse the oxidative decarboxylation of isocitrate into α-ketoglutarate (αKG). In gliomas and acute myeloid leukaemias, IDH1/2 mutations confer gain-of-function leading to production of the oncometabolite R-2-hydroxyglutarate (2HG) from αKG. Here we show that generation of 2HG by mutated IDH1/2 leads to the activation of mTOR by inhibiting KDM4A, an αKG-dependent enzyme of the Jumonji family of lysine demethylases. Furthermore, KDM4A associates with the DEP domain-containing mTOR-interacting protein (DEPTOR), a negative regulator of mTORC1/2. Depletion of KDM4A decreases DEPTOR protein stability. Our results provide an additional molecular mechanism for the oncogenic activity of mutant IDH1/2 by revealing an unprecedented link between TCA cycle defects and positive modulation of mTOR function downstream of the canonical PI3K/AKT/TSC1-2 pathway. PMID:27624942

  17. Is mTOR Inhibitor Good Enough for Treatment All Tumors in TSC Patients?

    PubMed Central

    Habib, Samy L; Al-Obaidi, Noor Y; Nowacki, Maciej; Pietkun, Katarzyna; Zegarska, Barbara; Kloskowski, Tomasz; Zegarski, Wojciech; Drewa, Tomasz; Medina, Edward A.; Zhao, Zhenze; Liang, Sitai

    2016-01-01

    Tuberous sclerosis complex (TSC) is an autosomal dominant and multi-system genetic disorder in humans. TSC affects around 25,000 to 40,000 individuals in the United States and about 1 to 2 million individuals worldwide, with an estimated prevalence of one in 6,000 newborns. TSC occurs in all races and ethnic groups, and in both genders. TSC is caused by defects or mutations in two genes, TSC1 and TSC2. Loss of TSC1/TSC2 leads to dysregulation of mTOR, resulting in aberrant cell differentiation and development, and abnormal enlargement of cells. TSC is characterized by the development of benign and/or malignant tumors in several organs including renal/liver angiomyolipomas, facial angiofibroma, lymphangiomyomatosis, cardiac rhabdomyomas, retinal astrocytic, renal cell carcinoma, and brain subependymal giant cell astrocytomas (SEGA). In addition, TSC disease causes disabling neurologic disorders, including epilepsy, mental retardation and autism. Particularly problematic are the development of renal angiomyolipomas, which tend to be larger, bilateral, multifocal and present at a younger age compared with sporadic forms. In addition, SEGA block the flow of fluid within the brain, causing a buildup of fluid and pressure that leads to blurred vision and seizures. In the current review, we describe the pathology of TSC disease in key organs and summarize the use of mTOR inhibitors to treat tumors in TSC patients. PMID:27698899

  18. Cyclin B Translation Depends on mTOR Activity after Fertilization in Sea Urchin Embryos.

    PubMed

    Chassé, Héloïse; Mulner-Lorillon, Odile; Boulben, Sandrine; Glippa, Virginie; Morales, Julia; Cormier, Patrick

    2016-01-01

    The cyclin B/CDK1 complex is a key regulator of mitotic entry. Using PP242, a specific ATP-competitive inhibitor of mTOR kinase, we provide evidence that the mTOR signalling pathway controls cyclin B mRNA translation following fertilization in Sphaerechinus granularis and Paracentrotus lividus. We show that PP242 inhibits the degradation of the cap-dependent translation repressor 4E-BP (eukaryotic initiation factor 4E-Binding Protein). PP242 inhibits global protein synthesis, delays cyclin B accumulation, cyclin B/CDK1 complex activation and consequently entry into the mitotic phase of the cell cycle triggered by fertilization. PP242 inhibits cyclin B mRNA recruitment into active polysomes triggered by fertilization. An amount of cyclin B mRNA present in active polysomes appears to be insensitive to PP242 treatment. Taken together, our results suggest that, following sea urchin egg fertilization, cyclin B mRNA translation is controlled by two independent mechanisms: a PP242-sensitive and an additional PP242-insentitive mechanism. PMID:26962866

  19. mTOR signaling regulates the processing of pre-rRNA in human cells

    PubMed Central

    Iadevaia, Valentina; Zhang, Ze; Jan, Eric; Proud, Christopher G.

    2012-01-01

    Signaling through the mammalian target of rapamycin, complex 1 (mTORC1), positively regulates the transcription of ribosomal RNA (rRNA) and the synthesis of ribosomal proteins, thereby promoting the complex process of ribosome biogenesis. The major rRNAs are transcribed as a single precursor, which must be processed to create the 5.8S, 18S and 28S rRNAs. We used a new non-radioactive labeling approach to study the effects of rapamycin, an inhibitor of mTORC1, on rRNA synthesis. Rapamycin not only impaired synthesis of new 18S, 28S or 5S rRNA but also induced their decay. This prompted us to examine the effects of rapamycin on rRNA processing. We show that rapamycin also interferes with the processing events that generate 18S and 28S rRNA. rRNA transcription and processing occur in regions of the nucleus known as nucleoli. We find that the mTORC1 components raptor and mTOR are both present in nucleoli, where they may regulate rRNA maturation events. While rapamycin has no effect on overall nucleolar morphology or its proteome, it does induce loss of mTOR and raptor from them. These data show that mTORC1 is located in nucleoli where it acts to regulate events involved in ribosome biogenesis including the maturation of rRNA molecules. PMID:22121221

  20. MAF mediates crosstalk between Ras-MAPK and mTOR signaling in NF1

    PubMed Central

    Brundage, Meghan E.; Tandon, Preeti; Eaves, David W.; Williams, Jon P.; Miller, Shyra J.; Hennigan, Robert H.; Jegga, Anil; Cripe, Timothy P.; Ratner, Nancy

    2014-01-01

    Mutations in the neurofibromatosis type 1 (NF1 tumor suppressor gene are common in cancer, and can cause resistance to therapy. Using transcriptome analysis we identified MAF as an NF1 regulated transcription factor, and verified MAF regulation through RAS/MAPK/AP-1 signaling in malignant peripheral nerve sheath tumor (MPNST) cell lines. MAF was also downregulated in human MPNST. Acute re-expression of MAF promoted expression of glial differentiation markers in MPNST cells in vitro, decreased self-renewal of embryonic precursors and transiently affected tumor cell phenotypes in vitro by increasing MPNST cell death and reducing metabolic activity and anchorage independent growth. Paradoxically, chronic MAF overexpression enhanced MPNST cell tumor growth in vivo, correlating with elevated pS6 in vitro and in vivo. RAD001 blocked MAF-mediated tumor growth, and MAF regulated the mTOR pathway through DEPTOR. MAPK inhibition with NF1 loss of function is predicted to show limited efficacy due to reactivation of mTOR signaling via MAF. PMID:24509877

  1. Cyclin B Translation Depends on mTOR Activity after Fertilization in Sea Urchin Embryos

    PubMed Central

    Boulben, Sandrine; Glippa, Virginie; Morales, Julia; Cormier, Patrick

    2016-01-01

    The cyclin B/CDK1 complex is a key regulator of mitotic entry. Using PP242, a specific ATP-competitive inhibitor of mTOR kinase, we provide evidence that the mTOR signalling pathway controls cyclin B mRNA translation following fertilization in Sphaerechinus granularis and Paracentrotus lividus. We show that PP242 inhibits the degradation of the cap-dependent translation repressor 4E-BP (eukaryotic initiation factor 4E-Binding Protein). PP242 inhibits global protein synthesis, delays cyclin B accumulation, cyclin B/CDK1 complex activation and consequently entry into the mitotic phase of the cell cycle triggered by fertilization. PP242 inhibits cyclin B mRNA recruitment into active polysomes triggered by fertilization. An amount of cyclin B mRNA present in active polysomes appears to be insensitive to PP242 treatment. Taken together, our results suggest that, following sea urchin egg fertilization, cyclin B mRNA translation is controlled by two independent mechanisms: a PP242-sensitive and an additional PP242-insentitive mechanism. PMID:26962866

  2. PTEN deficiency mediates a reciprocal response to IGF-1 and mTOR inhibition

    PubMed Central

    Patel, Mukund; Gomez, Nicholas C.; McFadden, Andrew W.; Moats-Staats, Billie M.; Wu, Sam; Rojas, Andres; Sapp, Travis; Simon, Jeremy M.; Smith, Scott V.; Kaiser-Rogers, Kathleen; Davis, Ian J.

    2014-01-01

    Recent evidence implicates the insulin-like growth factor (IGF) pathway in development of Ewing Sarcoma, a highly malignant bone and soft tissue tumor that primarily affects children and young adults. Despite promising results from preclinical studies of therapies that target this pathway, early phase clinical trials have shown that a significant fraction of patients do not benefit, suggesting that cellular factors determine tumor sensitivity. Using FAIRE-seq, a chromosomal deletion of the PTEN locus in a Ewing sarcoma cell line was identified. In primary tumors PTEN deficiency was observed in a large subset of cases, although not mediated by large chromosomal deletions. PTEN loss resulted in hyper-activation of the AKT signaling pathway. PTEN rescue led to decreased proliferation, inhibition of colony formation, and increased apoptosis. Strikingly, PTEN loss decreased sensitivity to IGF-1R inhibitors but increased responsiveness to temsirolimus, a potent mTOR inhibitor, as marked by induction of autophagy. These results suggest that PTEN is lost in a significant fraction of primary tumors and this deficiency may have therapeutic consequences by concurrently attenuating responsiveness to IGF-1R inhibition while increasing activity of mTOR inhibitors. The identification of PTEN status in the tumors of patients with recurrent disease could help guide the selection of therapies. PMID:24994750

  3. SUBTYPE-SPECIFIC REGENERATION OF RETINAL GANGLION CELLS FOLLOWING AXOTOMY: EFFECTS OF OSTEOPONTIN AND MTOR SIGNALING

    PubMed Central

    Duan, Xin; Qiao, Mu; Bei, Fengfeng; Kim, In-Jung; He, Zhigang; Sanes, Joshua R.

    2015-01-01

    SUMMARY In mammals, few retinal ganglion cells (RGCs) survive following axotomy and even fewer regenerate axons. This could reflect differential extrinsic influences or the existence of subpopulations that vary in their responses to injury. We tested these alternatives by comparing responses of molecularly distinct subsets of mouse RGCs to axotomy. Survival rates varied dramatically among subtypes, with alpha-RGCs (αRGCs) surviving preferentially. Among survivors, αRGCs accounted for nearly all regeneration following down-regulation of PTEN, which activates the mTOR pathway. αRGCs have uniquely high mTOR signaling levels among RGCs and also selectively express osteopontin (OPN) and receptors for the growth factor, insulin-like growth factor 1 (IGF-1). Administration of OPN plus IGF-1 promotes regeneration as effectively as down-regulation of PTEN; however, regeneration is still confined to αRGCs. Our results reveal dramatic subtype-specific differences in the ability of RGCs to survive and regenerate following injury, and they identify promising agents for promoting axonal regeneration. PMID:25754821

  4. mTOR inhibition improves antitumor effects of vaccination with antigen-encoding RNA.

    PubMed

    Diken, Mustafa; Kreiter, Sebastian; Vascotto, Fulvia; Selmi, Abderraouf; Attig, Sebastian; Diekmann, Jan; Huber, Christoph; Türeci, Özlem; Sahin, Ugur

    2013-12-01

    Vaccination with in vitro transcribed RNA encoding tumor antigens is an emerging approach in cancer immunotherapy. Attempting to further improve RNA vaccine efficacy, we have explored combining RNA with immunomodulators such as rapamycin. Rapamycin, the inhibitor of mTOR, was used originally for immunosuppression. Recent reports in mouse systems, however, suggest that mTOR inhibition may enhance the formation and differentiation of the memory CD8(+) T-cell pool. Because memory T-cell formation is critical to the outcome of vaccination approaches, we studied the impact of rapamycin on the in vivo primed RNA vaccine-induced immune response using the chicken ovalbumin-expressing B16 melanoma model in C57BL/6 mice. Our data show that treatment with rapamycin at the effector-to-memory transition phase skews the vaccine-induced immune response toward the formation of a quantitatively and qualitatively superior memory pool and results in a better recall response. Tumor-infiltrating immune cells from these mice display a favorable ratio of effector versus suppressor cell populations. Survival of mice treated with the combined regimen of RNA vaccination with rapamycin is significantly longer (91.5 days) than that in the control groups receiving only one of these compounds (32 and 46 days, respectively). Our findings indicate that rapamycin enhances therapeutic efficacy of antigen-specific CD8(+) T cells induced by RNA vaccination, and we propose further clinical exploration of rapamycin as a component of immunotherapeutic regimens. PMID:24778131

  5. Prevention of allograft rejection in heart transplantation through concurrent gene silencing of TLR and Kinase signaling pathways

    PubMed Central

    Wang, Hongmei; Zhang, Xusheng; Zheng, Xiufen; Lan, Zhu; Shi, Jun; Jiang, Jifu; Zwiep, Terry; Li, Qing; Quan, Douglas; Zhang, Zhu-Xu; Min, Weiping

    2016-01-01

    Toll-like receptors (TLRs) act as initiators and conductors responsible for both innate and adaptive immune responses in organ transplantation. The mammalian target of rapamycin (mTOR) is one of the most critical signaling kinases that affects broad aspects of cellular functions including metabolism, growth, and survival. Recipients (BALB/c) were treated with MyD88, TRIF and mTOR siRNA vectors, 3 and 7 days prior to heart transplantation and 7, 14 and 21 days after transplantation. After siRNA treatment, recipients received a fully MHC-mismatched C57BL/6 heart. Treatment with mTOR siRNA significantly prolonged allograft survival in heart transplantation. Moreover, the combination of mTOR siRNA with MyD88 and TRIF siRNA further extended the allograft survival; Flow cytometric analysis showed an upregulation of FoxP3 expression in spleen lymphocytes and a concurrent downregulation of CD40, CD86 expression, upregulation of PD-L1 expression in splenic dendritic cells in MyD88, TRIF and mTOR treated mice. There is significantly upregulated T cell exhaustion in T cells isolated from tolerant recipients. This study is the first demonstration of preventing immune rejection of allogeneic heart grafts through concurrent gene silencing of TLR and kinase signaling pathways, highlighting the therapeutic potential of siRNA in clinical transplantation. PMID:27659428

  6. Mutation-targeted therapy with sunitinib or everolimus in patients with advanced low-grade or intermediate-grade neuroendocrine tumours of the gastrointestinal tract and pancreas with or without cytoreductive surgery: protocol for a phase II clinical trial

    PubMed Central

    Neychev, Vladimir; Steinberg, Seth M; Cottle-Delisle, Candice; Merkel, Roxanne; Nilubol, Naris; Yao, Jianhua; Meltzer, Paul; Pacak, Karel; Marx, Stephen; Kebebew, Electron

    2015-01-01

    Introduction Finding the optimal management strategy for patients with advanced, metastatic neuroendocrine tumours (NETs) of the gastrointestinal tract and pancreas is a work in progress. Sunitinib and everolimus are currently approved for the treatment of progressive, unresectable, locally advanced or metastatic low-grade or intermediate-grade pancreatic NETs. However, mutation-targeted therapy with sunitinib or everolimus has not been studied in this patient population. Methods and analysis This prospective, open-label phase II clinical trial was designed to determine if mutation-targeting therapy with sunitinib or everolimus for patients with advanced low-grade or intermediate-grade NETs is more effective than historically expected results with progression-free survival (PFS) as the primary end point. Patients ≥18 years of age with progressive, low-grade or intermediate-grade locally advanced or metastatic NETs are eligible for this study. Patients will undergo tumour biopsy (if they are not a surgical candidate) for tumour genotyping. Patients will be assigned to sunitininb or everolimus based on somatic/germline mutations profile. Patients who have disease progression on either sunitinib or everolimus will crossover to the other drug. Treatment will continue until disease progression, unacceptable toxicity, or consent to withdrawal. Using the proposed criteria, 44 patients will be accrued within each treatment group during a 48-month period (a total of 88 patients for the 2 treatments), and followed for up to an additional 12 months (a total of 60 months from entry of the first patient) to achieve 80% power in order to test whether there is an improvement in PFS compared to historically expected results, with a 0.10 α level one-sided significance test. Ethics and dissemination The study protocol was approved by the institutional review board of the National Cancer Institute (NCI-IRB Number 15C0040; iRIS Reference Number 339636). The results will be

  7. Mechanistic target of rapamycin (mTOR) signaling genes in decapod crustaceans: cloning and tissue expression of mTOR, Akt, Rheb, and p70 S6 kinase in the green crab, Carcinus maenas, and blackback land crab, Gecarcinus lateralis.

    PubMed

    Abuhagr, Ali M; Maclea, Kyle S; Chang, Ernest S; Mykles, Donald L

    2014-02-01

    Mechanistic target of rapamycin (mTOR) controls global translation of mRNA into protein by phosphorylating p70 S6 kinase (S6K) and eIF4E-binding protein-1. Akt and Rheb, a GTP-binding protein, regulate mTOR protein kinase activity. Molting in crustaceans is regulated by ecdysteroids synthesized by a pair of molting glands, or Y-organs (YOs), located in the cephalothorax. During premolt, the YOs hypertrophy and increase production of ecdysteroids. Rapamycin (1μM) inhibited ecdysteroid secretion in Carcinus maenas and Gecarcinus lateralis YOs in vitro, indicating that ecdysteroidogenesis requires mTOR-dependent protein synthesis. The effects of molting on the expression of four key mTOR signaling genes (mTOR, Akt, Rheb, and S6K) in the YO was investigated. Partial cDNAs encoding green crab (C. maenas) mTOR (4031bp), Akt (855bp), and S6K (918bp) were obtained from expressed sequence tags. Identity/similarity of the deduced amino acid sequence of the C. maenas cDNAs to human orthologs were 72%/81% for Cm-mTOR, 58%/73% for Cm-Akt, and 77%/88% for Cm-S6K. mTOR, Akt, S6K, and elongation factor 2 (EF2) in C. maenas and blackback land crab (G. lateralis) were expressed in all tissues examined. The two species differed in the effects of molting on gene expression in the YO. In G. lateralis, Gl-mTOR, Gl-Akt, and Gl-EF2 mRNA levels were increased during premolt. By contrast, molting had no effect on the expression of Cm-mTOR, Cm-Akt, Cm-S6K, Cm-Rheb, and Cm-EF2. These data suggest that YO activation during premolt involves up regulation of mTOR signaling genes in G. lateralis, but is not required in C. maenas. PMID:24269559

  8. Alleviation of neuronal energy deficiency by mTOR inhibition as a treatment for mitochondria-related neurodegeneration

    PubMed Central

    Zheng, Xinde; Boyer, Leah; Jin, Mingji; Kim, Yongsung; Fan, Weiwei; Bardy, Cedric; Berggren, Travis; Evans, Ronald M; Gage, Fred H; Hunter, Tony

    2016-01-01

    mTOR inhibition is beneficial in neurodegenerative disease models and its effects are often attributable to the modulation of autophagy and anti-apoptosis. Here, we report a neglected but important bioenergetic effect of mTOR inhibition in neurons. mTOR inhibition by rapamycin significantly preserves neuronal ATP levels, particularly when oxidative phosphorylation is impaired, such as in neurons treated with mitochondrial inhibitors, or in neurons derived from maternally inherited Leigh syndrome (MILS) patient iPS cells with ATP synthase deficiency. Rapamycin treatment significantly improves the resistance of MILS neurons to glutamate toxicity. Surprisingly, in mitochondrially defective neurons, but not neuroprogenitor cells, ribosomal S6 and S6 kinase phosphorylation increased over time, despite activation of AMPK, which is often linked to mTOR inhibition. A rapamycin-induced decrease in protein synthesis, a major energy-consuming process, may account for its ATP-saving effect. We propose that a mild reduction in protein synthesis may have the potential to treat mitochondria-related neurodegeneration. DOI: http://dx.doi.org/10.7554/eLife.13378.001 PMID:27008180

  9. Down-regulation of mTOR leads to up-regulation of osteoprotegerin in bone marrow cells

    SciTech Connect

    Mogi, Makio; Kondo, Ayami

    2009-06-19

    Osteoprotegerin (OPG)/osteoclastogenesis inhibitory factor regulates bone mass by inhibiting osteoclastic bone resorption. mTOR, which is the mammalian target of rapamycin, is a kinase and central regulator of cell growth, proliferation, and survival. By using Rapamycin, we studied whether mTOR pathway is associated with OPG protein production in the mouse bone marrow-derived stromal cell line ST2. Rapamycin markedly increased the level of soluble OPG in ST2 cells. This antibiotic treatment resulted in the suppression of phosphorylation of mTOR. Rapamycin had no effects on the proliferation, differentiation, or apoptosis of the cells. Treatment with bone morphogenetic protein-4, which can induce OPG protein in ST2 cells, also resulted in a decrease in the density of the phospho-mTOR-band, suggesting that the suppression of the phospho-mTOR pathway is necessary for OPG production in ST2 cells. Thus, suitable suppression of mTOR phosphorylation is a necessary requirement for OPG production in bone marrow stromal cells.

  10. The general amino acid control pathway regulates mTOR and autophagy during serum/glutamine starvation.

    PubMed

    Chen, Rui; Zou, Yilong; Mao, Dongxue; Sun, Daxiao; Gao, Guanguang; Shi, Jingwen; Liu, Xiaoqing; Zhu, Chen; Yang, Mingyu; Ye, Wanlu; Hao, Qianqian; Li, Ruiqiang; Yu, Li

    2014-07-21

    Organisms have evolved elaborate mechanisms to adjust intracellular nutrient levels in response to fluctuating availability of exogenous nutrients. During starvation, cells can enhance amino acid uptake and synthesis through the general amino acid control (GAAC) pathway, whereas nonessential cellular contents are recycled by autophagy. How these two pathways are coordinated in response to starvation is currently unknown. Here we show that the GAAC pathway couples exogenous amino acid availability with autophagy. Starvation caused deactivation of mTOR, which then activated autophagy. In parallel, serum/glutamine starvation activated the GAAC pathway, which up-regulated amino acid transporters, leading to increased amino acid uptake. This elevated the intracellular amino acid level, which in turn reactivated mTOR and suppressed autophagy. Knockdown of activating transcription factor 4, the major transcription factor in the GAAC pathway, or of SLC7A5, a leucine transporter, caused impaired mTOR reactivation and much higher levels of autophagy. Thus, the GAAC pathway modulates autophagy by regulating amino acid uptake and mTOR reactivation during serum/glutamine starvation.

  11. mTOR Inhibition Improves Anaemia and Reduces Organ Damage in a Murine Model of Sickle Cell Disease

    PubMed Central

    Wang, Jintao; Tran, Jennifer; Wang, Hui; Guo, Chiao; Harro, David; Campbell, Andrew D.; Eitzman, Daniel T.

    2016-01-01

    Summary Mechanistic target of rapamycin (mTOR) has been shown to play an important role in red blood cell physiology, with inhibition of mTOR signalling leading to alterations in erythropoiesis. To determine if mTOR inhibition would improve anaemia in sickle cell disease (SCD), mice with SCD were treated with the dual mTORC1/2 inhibitor, INK128. 1 week after daily oral drug treatment, erythrocyte count, haemoglobin, and haematocrit were all significantly increased while reticulocyte counts were reduced. These parameters remained stable during 3 weeks of treatment. Similar effects were observed following oral treatment with the mTORC1 inhibitor, sirolimus. Sirolimus treatment prolonged the lifespan of sickle cell erythrocytes in circulation, reduced spleen size, and reduced renal and hepatic iron accumulation in SCD mice. Following middle cerebral artery occlusion, stroke size was reduced in SCD mice treated with sirolimus. In conclusion, mTOR inhibition is protective against anaemia and organ damage in a murine model of SCD. PMID:27030515

  12. Estradiol-Induced Object Recognition Memory Consolidation Is Dependent on Activation of mTOR Signaling in the Dorsal Hippocampus

    ERIC Educational Resources Information Center

    Fortress, Ashley M.; Fan, Lu; Orr, Patrick T.; Zhao, Zaorui; Frick, Karyn M.

    2013-01-01

    The mammalian target of rapamycin (mTOR) signaling pathway is an important regulator of protein synthesis and is essential for various forms of hippocampal memory. Here, we asked whether the enhancement of object recognition memory consolidation produced by dorsal hippocampal infusion of 17[Beta]-estradiol (E[subscript 2]) is dependent on mTOR…

  13. Effects of chronic overload on muscle hypertrophy and mTOR signaling in adult and aged rats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We examined the effect of 28 days of overload on mammalian target of rapamycin (mTOR) and extracellular signal-regulated kinase (ERK) signaling in young adult (Y; 6 mo old) and aged (O; 30 mo old) Fischer 344 x Brown Norway rats subjected to bilateral synergist ablation (SA) of two-thirds of the gas...

  14. Downregulation of cancer stem cell properties via mTOR signaling pathway inhibition by rapamycin in nasopharyngeal carcinoma

    PubMed Central

    YANG, CHUNGUANG; ZHANG, YUE; ZHANG, YU; ZHANG, ZIHENG; PENG, JIANHUA; LI, ZHI; HAN, LIANG; YOU, QUANJIE; CHEN, XIAOYU; RAO, XINGWANG; ZHU, YI; LIAO, ZHISU

    2015-01-01

    Rapamycin, a mammalian target of rapamycin (mTOR) signaling inhibitor, inhibits cancer cell proliferation and tumor formation, including in nasopharyngeal carcinoma (NPC), which we proved in a previous study. However, whether rapamycin affects cancer stem cells (CSCs) is unclear. In examining samples of NPCs, we found regions of CD44-positive cancer cells co-expressing the stem cell biomarker OCT4, suggesting the presence of CSCs. Following this, we used double-label immunohistochemistry to identify whether the mTOR signaling pathway was activated in CD44-positive CSCs in NPCs. We used a CCK-8 assay and western blotting to explore whether the stem cell biomarkers CD44 and SOX2 and the invasion protein MMP-2 could be suppressed by treatment with rapamycin in cultured primary NPC cells and secondary tumors in BALB/c nude mice. Interestingly, we found that rapamycin inhibited mTOR signaling in addition to simultaneously downregulating the expression of CD44, SOX2 and MMP-2 and that it affected cell growth and tumor size and weight both in vitro and in vivo. Collectively, we confirmed for the first time that CSC properties are reduced and invasion potential is restrained in response to mTOR signaling inhibition in NPC. This evidence indicates that the targeted inhibition of CSC properties may provide a novel strategy to treat cancer. PMID:26202311

  15. WISP3 (CCN6) Regulates Milk Protein Synthesis and Cell Growth Through mTOR Signaling in Dairy Cow Mammary Epithelial Cells.

    PubMed

    Jiang, Nan; Wang, Yu; Yu, Zhiqiang; Hu, Lijun; Liu, Chaonan; Gao, Xueli; Zheng, Shimin

    2015-08-01

    The mTOR/S6K1 signaling pathway is the primary regulator of milk protein synthesis. While mTOR is known to be regulated at the translational level by amino acids, the mechanism by which mTOR accepts the amino acid signal is not yet clear. In this study, we describe the discovery of WISP3 as a potentially novel signaling factor that connects mTOR and amino acids. Treatment of dairy cow mammary epithelial cells with amino acids (lysine or methionine) increased both cell growth and the expression of β-casein (CSN2), WISP3, mTOR, and phospho-mTOR (p-mTOR). Notably, overexpressing WISP3 in these cells also increased both cell growth and the expression of CSN2, mTOR, and p-mTOR and decreased the expression of glycogen synthase kinase 3β (GSK3β), while repressing WISP3 had the opposite effect. The increase of the expression of CSN2, mTOR, and p-mTOR mediated by amino acid could be inhibited by repressing WISP3. The increase of the expression of CSN2, mTOR, and p-mTOR mediated by WISP3 overexpression could be inhibited by overexpressing GSK3β, and vice versa. Taken together, these results reveal that through its amino acid-mediated regulation of the mTOR pathway, WISP3 is an important regulatory factor involved in the amino acid-mediated regulation of milk protein synthesis and cell growth. PMID:26061139

  16. Spinster is required for autophagic lysosome reformation and mTOR reactivation following starvation.

    PubMed

    Rong, Yueguang; McPhee, Christina K; McPhee, Christina; Deng, Shuangshen; Huang, Lei; Chen, Lilian; Liu, Mei; Tracy, Kirsten; Baehrecke, Eric H; Baehreck, Eric H; Yu, Li; Lenardo, Michael J

    2011-05-10

    Autophagy is a conserved cellular process to degrade and recycle cytoplasmic components. During autophagy, lysosomes fuse with an autophagosome to form an autolysosome. Sequestered components are degraded by lysosomal hydrolases and presumably released into the cytosol by lysosomal efflux permeases. Following starvation-induced autophagy, lysosome homeostasis is restored by autophagic lysosome reformation (ALR) requiring activation of the "target of rapamycin" (TOR) kinase. Spinster (Spin) encodes a putative lysosomal efflux permease with the hallmarks of a sugar transporter. Drosophila spin mutants accumulate lysosomal carbohydrates and enlarged lysosomes. Here we show that defects in spin lead to the accumulation of enlarged autolysosomes. We find that spin is essential for mTOR reactivation and lysosome reformation following prolonged starvation. Further, we demonstrate that the sugar transporter activity of Spin is essential for ALR.

  17. mTOR, AMPK, and Sirt1: Key Players in Metabolic Stress Management.

    PubMed

    Cetrullo, Silvia; D'Adamo, Stefania; Tantini, Benedetta; Borzi, Rosa Maria; Flamigni, Flavio

    2015-01-01

    Cells adapt their metabolism and activities in response to signals from their surroundings, and this ability is essential for their survival in the face of environmental changes. In mammalian tissues a deficit of these mechanisms is commonly associated with cellular aging and degenerative diseases related to aging, such as cardiovascular disease, cancer, immune system decline, and neurological pathologies. Several proteins have been identified as able to respond directly to energy, nutrient, and growth factor levels and stress stimuli in order to mediate adaptations in the cell. Many of these proteins are enzymes that positively or negatively modulate the autophagic process. This review focuses on biochemical mechanisms involving enzymes--specifically, mTOR, AMPK, and Sirt1--that are currently considered important for these adaptive responses, providing an overview of the interactions of the main players in this process.

  18. mTOR Pathway Mutations Cause Hemimegalencephaly and Focal Cortical Dysplasia

    PubMed Central

    D'Gama, Alissa M.; Geng, Ying; Couto, Javier A.; Martin, Beth; Boyle, Evan A.; LaCoursiere, Christopher M.; Hossain, Amer; Hatem, Nicole E.; Barry, Brenda; Kwiatkowski, David J.; Vinters, Harry V.; Barkovich, A. James; Shendure, Jay; Mathern, Gary W.; Walsh, Christopher A.; Poduri, Annapurna

    2015-01-01

    Focal malformations of cortical development, including focal cortical dysplasia (FCD) and hemimegalencephaly (HME), are important causes of intractable childhood epilepsy. Using targeted and exome sequencing on DNA from resected brain samples and non-brain samples from 53 patients with FCD or HME, we identified pathogenic germline and mosaic mutations in multiple PI3K/AKT pathway genes in 9 patients, and a likely pathogenic variant in 1 additional patient. Our data confirm the association of DEPDC5 with sporadic FCD but also implicate this gene for the first time in HME. Our findings suggest that modulation of the mTOR pathway may hold promise for malformation-associated epilepsy. PMID:25599672

  19. M(o)TOR of aging: MTOR as a universal molecular hypothalamus.

    PubMed

    Blagosklonny, Mikhail V

    2013-07-01

    A recent ground-breaking publication described hypothalamus-driven programmatic aging. As a Russian proverb goes "everything new is well-forgotten old". In 1958, Dilman proposed that aging and its related diseases are programmed by the hypothalamus. This theory, supported by beautiful experiments, remained unnoticed just to be re-discovered recently. Yet, it does not explain all manifestations of aging. And would organism age without hypothalamus? Do sensing pathways such as MTOR (mechanistic Target of Rapamycin) and IKK-beta play a role of a "molecular hypothalamus" in every cell? Are hypothalamus-driven alterations simply a part of quasi-programmed aging manifested by hyperfunction and secondary signal-resistance? Here are some answers.

  20. MTOR-driven quasi-programmed aging as a disposable soma theory

    PubMed Central

    2013-01-01

    If life were created by intelligent design, we would indeed age from accumulation of molecular damage. Repair is costly and limited by energetic resources, and we would allocate resources rationally. But, albeit elegant, this design is fictional. Instead, nature blindly selects for short-term benefits of robust developmental growth. “Quasi-programmed” by the blind watchmaker, aging is a wasteful and aimless continuation of developmental growth, driven by nutrient-sensing, growth-promoting signaling pathways such as MTOR (mechanistic target of rapamycin). A continuous post-developmental activity of such gerogenic pathways leads to hyperfunctions (aging), loss of homeostasis, age-related diseases, non-random organ damage and death. This model is consistent with a view that (1) soma is disposable, (2) aging and menopause are not programmed and (3) accumulation of random molecular damage is not a cause of aging as we know it. PMID:23708516

  1. Predictive factors of response to mTOR inhibitors in neuroendocrine tumours.

    PubMed

    Zatelli, Maria Chiara; Fanciulli, Giuseppe; Malandrino, Pasqualino; Ramundo, Valeria; Faggiano, Antongiulio; Colao, Annamaria

    2016-03-01

    Medical treatment of neuroendocrine tumours (NETs) has drawn a lot of attention due to the recent demonstration of efficacy of several drugs on progression-free survival, including somatostatin analogs, small tyrosine kinase inhibitors and mTOR inhibitors (or rapalogs). The latter are approved as therapeutic agents in advanced pancreatic NETs and have been demonstrated to be effective in different types of NETs, with variable efficacy due to the development of resistance to treatment. Early detection of patients that may benefit from rapalogs treatment is of paramount importance in order to select the better treatment and avoid ineffective and expensive treatments. Predictive markers for therapeutic response are under intensive investigation, aiming at a tailored patient management and more appropriate resource utilization. This review summarizes the available data on the tissue, circulating and imaging markers that are potentially predictive of rapalog efficacy in NETs. PMID:26666705

  2. Predictive factors of response to mTOR inhibitors in neuroendocrine tumours.

    PubMed

    Zatelli, Maria Chiara; Fanciulli, Giuseppe; Malandrino, Pasqualino; Ramundo, Valeria; Faggiano, Antongiulio; Colao, Annamaria

    2016-03-01

    Medical treatment of neuroendocrine tumours (NETs) has drawn a lot of attention due to the recent demonstration of efficacy of several drugs on progression-free survival, including somatostatin analogs, small tyrosine kinase inhibitors and mTOR inhibitors (or rapalogs). The latter are approved as therapeutic agents in advanced pancreatic NETs and have been demonstrated to be effective in different types of NETs, with variable efficacy due to the development of resistance to treatment. Early detection of patients that may benefit from rapalogs treatment is of paramount importance in order to select the better treatment and avoid ineffective and expensive treatments. Predictive markers for therapeutic response are under intensive investigation, aiming at a tailored patient management and more appropriate resource utilization. This review summarizes the available data on the tissue, circulating and imaging markers that are potentially predictive of rapalog efficacy in NETs.

  3. SIRT1 controls liver regeneration by regulating BA metabolism through FXR and mTOR signaling

    PubMed Central

    García-Rodríguez, Juan L.; Barbier-Torres, Lucía; Fernández-Álvarez, Sara; Juan, Virginia Gutiérrez-de; Monte, María J.; Halilbasic, Emina; Herranz, Daniel; Álvarez, Luis; Aspichueta, Patricia; Marín, Jose J. G.; Trauner, Michael; Mato, Jose M.; Serrano, Manuel; Beraza, Naiara; Martínez-Chantar, María Luz

    2014-01-01

    Sirtuin1 (SIRT1) regulates central metabolic functions such as lipogenesis, protein synthesis, gluconeogenesis and bile acid (BA) homeostasis through deacetylation. Here, we describe that SIRT1 tightly controls the regenerative response of the liver. We performed partial hepatectomy (PH) to transgenic mice that overexpress SIRT1 (SIRT). SIRT mice showed increased mortality, impaired hepatocyte proliferation, BA accumulation and profuse liver injury after surgery. The damaging phenotype in SIRT mice correlated with impaired FXR activity due to persistent deacetylation and lower protein expression that led to decreased FXR-target gene expression; SHP, BSEP and increased Cyp7A1. Next, we convincingly show that 24-norUrsodeoxycholic acid (NorUDCA) attenuates SIRT protein expression, increases the acetylation of FXR and neighboring histones, restores trimethylation of H3K4 and H3K9 and increases miR34a expression, thus re-establishing BA homeostasis. Consequently, NorUDCA restored liver regeneration in SIRT mice, which showed increased survival and hepatocyte proliferation. Furthermore, a Leucine-enriched diet restored mTOR activation, acetylation of FXR and histones, leading to an overall lower BA production through SHP-inhibition of Cyp7A1 and higher transport (BSEP) and detoxification (Sult2a1) leading to an improved liver regeneration. Finally, we found that human HCC samples have increased presence of SIRT1, which correlated with absence of FXR suggesting its oncogenic potential. Conclusions Overall, we define SIRT1 as a key regulator of the regenerative response in the liver through post-transcriptional modifications that regulate the activity of FXR, histones and mTOR. Moreover, our data suggest that SIRT1 contributes to liver tumorigenesis through dysregulation of BA homeostasis by persistent FXR deacetylation. PMID:24338587

  4. Species difference in glucuronidation formation kinetics with a selective mTOR inhibitor.

    PubMed

    Berry, Loren M; Liu, Jingzhou; Colletti, Adria; Krolikowski, Paul; Zhao, Zhiyang; Teffera, Yohannes

    2014-04-01

    The mammalian target of rapamycin (mTOR) is a protein kinase that shows key involvement in age-related disease and promises to be a target for treatment of cancer. In the present study, the elimination of potent ATP-competitive mTOR inhibitor 3-(6-amino-2-methylpyrimidin-4-yl)-N-(1H-pyrazol-3-yl)imidazo[1,2-b]pyridazin-2-amine (compound 1) is studied in bile duct-cannulated rats, and the metabolism of compound 1 in liver microsomes is compared across species. Compound 1 was shown to undergo extensive N-glucuronidation in bile duct-catheterized rats. N-glucuronides were detected on positions N1 (M2) and N2 (M1) of the pyrazole moiety as well as on the primary amine (M3). All three N-glucuronide metabolites were detected in liver microsomes of the rat, dog, and human, while primary amine glucuronidation was not detected in cynomolgus monkey. In addition, N1- and N2-glucuronidation showed strong species selectivity in vitro, with rat, dog, and human favoring N2-glucuronidation and monkey favoring N1-glucuronide formation. Formation of M1 in monkey liver microsomes also followed sigmoidal kinetics, singling out monkey as unique among the species with regard to compound 1 N-glucuronidation. In this respect, monkeys might not always be the best animal model for N-glucuronidation of uridine diphosphate glucuronosyltransferase (UGT) 1A9 or UGT1A1 substrates in humans. The impact of N-glucuronidation of compound 1 could be more pronounced in higher species such as monkey and human, leading to high clearance in these species. While compound 1 shows promise as a candidate for investigating the impact of pan-mTOR inhibition in vivo, opportunities may exist through medicinal chemistry efforts to reduce metabolic liability with the goal of improving systemic exposure. PMID:24423753

  5. Adverse Cardiovascular Outcomes associated with Coronary Artery Bypass Surgery and Percutaneous Coronary Intervention with Everolimus Eluting Stents: A Meta-Analysis

    PubMed Central

    Bundhun, Pravesh Kumar; Pursun, Manish; Teeluck, Abhishek Rishikesh; Bhurtu, Akash; Soogund, Mohammad Zafooruddin Sani; Huang, Wei-Qiang

    2016-01-01

    This study aimed to compare the mid-term adverse cardiovascular outcomes associated with Coronary Artery Bypass Surgery (CABG) and Percutaneous Coronary Intervention (PCI) with Everolimus Eluting Stents (EES). Electronic databases were searched for studies comparing the mid-term (>1 year) adverse cardiovascular outcomes between CABG and PCI with EES. Odd Ratios (OR) with 95% Confidence Intervals (CIs) were calculated and the pooled analyses were performed with RevMan 5.3 software. A total number of 5207 patients were involved in this analysis. No significant difference was observed in mortality between CABG and EES with OR: 0.90, 95% CI: 0.73–1.10; P = 0.30. Moreover, CABG was associated with a high stroke rate, with OR: 0.73, 95% CI: 0.45–1.17; P = 0.19, without any statistical significant. CABG was associated with significantly lower Major Adverse Cardiac Events and Myocardial Infarction with OR: 1.46, 95% CI: 1.05–2.04; P = 0.03 and OR: 1.46, 95% CI: 1.01–2.12; P = 0.05 respectively whereas PCI was associated with a significantly higher repeated revascularization with OR: 2.21; 95% CI: 1.76–2.77; P = 0.00001. In conclusion, significant differences were noted in several subgroups analyzing the mid-term cardiovascular outcomes between CABG and EES. PMID:27775055

  6. Pilot conversion trial from mycophenolic acid to everolimus in ABO-incompatible kidney-transplant recipients with BK viruria and/or viremia.

    PubMed

    Belliere, Julie; Kamar, Nassim; Mengelle, Catherine; Allal, Asma; Sallusto, Federico; Doumerc, Nicolas; Game, Xavier; Congy-Jolivet, Nicolas; Esposito, Laure; Debiol, Benedicte; Rostaing, Lionel

    2016-03-01

    Immunosuppression using everolimus (EVR) plus low-dose tacrolimus (Tac) is commonly used in organ transplantation. EVR has potential antiviral effects. Herein, the long-term outcomes and impacts of Tac-EVR on the BK virus are reported in ABO-incompatible kidney-transplant recipients. The initial immunosuppressive regimen combined steroids, Tac, and mycophenolic acid (MPA). At a median of 141 (34-529) days post-transplantation, seven stable ABO-incompatible kidney-transplant recipients were converted from MPA to EVR because of active BK replication, and compared with a reference group of fourteen ABO-incompatible patients receiving classical Tac plus MPA. At 1 month before conversion, at 1, 3 months after, and at last follow-up, clinical and biological parameters were monitored. The median time from conversion to the last follow-up was 784 (398-866) days. Conversion to EVR caused no change to rejection episodes or immunological status (isoagglutinin titers, anti-HLA antibodies). At last follow-up, median eGFR was similar in the Tac-MPA versus Tac-EVR group (40 [range: 14-56] vs. 54.5 ml/min/1.73 m(2) [range: 0-128], P = 0.07). The major adverse event was dyslipidemia. Interestingly, conversion from MPA to EVR decreased BK viral load in five patients. ABO-incompatible kidney-transplant recipients with an active BK virus infection may benefit from conversion to EVR. PMID:26575959

  7. mTOR Modulates Lymphocyte Differentiation through T-bet and Eomesodermin in Response to Invasive Pulmonary Aspergillosis in Rats

    PubMed Central

    Cui, Na; Su, Long-Xiang; Wang, Hao; Xiao, Meng; Yang, Fei; Zheng, Min; Li, Xin; Xu, Ying-Chun; Liu, Da-Wei

    2016-01-01

    Background: Aspergillosis infection is common in the patients with insufficient immunity. The role of mammalian target of rapamycin (mTOR), T-box expressed in T-cells (T-bet), and eomesodermin (EOMES) in mediating T lymphocytes differentiation in response to Aspergillus fumigatus infection in immunocompromised rats was investigated in this study. Methods: Invasive pulmonary aspergillosis (IPA) of immunosuppressive twenty male rats were established and sacrificed at 24 h (n = 5), 48 h (n = 5), 72 h (n = 5), and 96 h (n = 5) after A. fumigatus infection. In addition, control (n = 5), cyclophosphamide (CTX) (n = 5), and aspergillosis (n = 5) group were also established the tissues and pathology of lung tissue was examined by hematoxylin and eosin staining. CD8+ T-cells was sorted by flow cytometry. Serum mTOR, S6K, T-bet, and EOMES were quantified by enzyme-linked immunosorbent assay. Results: Histology of lung tissue indicated severe lung tissue injury including infiltration of inflammatory cells, alveolar wall damage or degradation, blood congestion, and hemorrhage in the CTX, IPA, and CTX + IPA rats. Hyphae were seen in the IPA, and CTX + IPA groups. The proportion of CD8+ T-cells was significantly increased in the animals of CTX + IPA. Memory CD8+ T-cells was significantly increased in early stage (24 h and 48 h, P < 0.001), but decreased in the late phase of fungal infection (72 h and 96 h) in the animals of CTX + IPA. In addition, at early stage of fungal infection (24 h and 48 h), serum mTOR (P < 0.001), S6K (P < 0.001), and T-bet (P < 0.05) was significantly higher, while EOMES was significantly lower (P < 0.001), in CTX + IPA group than that in control, CTX alone or IPA alone group. Conversely, serum mTOR, S6K, T-bet, and EOMES showed opposite changed in the late stage (72 h and 96 h). Pearson's correlation analysis indicated that mTOR and S6K were significantly correlated with T-bet (r = 0.901 and 0.91, respectively, P < 0.001), but negatively and

  8. In search of antiaging modalities: evaluation of mTOR- and ROS/DNA damage-signaling by cytometry.

    PubMed

    Darzynkiewicz, Zbigniew; Zhao, Hong; Halicka, H Dorota; Li, Jiangwei; Lee, Yong-Syu; Hsieh, Tze-Chen; Wu, Joseph M

    2014-05-01

    This review presents the evidence in support of the IGF-1/mTOR/S6K1 signaling as the primary factor contributing to aging and cellular senescence. Reviewed are also specific interactions between mTOR/S6K1 and ROS-DNA damage signaling pathways. Outlined are critical sites along these pathways, including autophagy, as targets for potential antiaging (gero-suppressive) and/or chemopreventive agents. Presented are applications of flow- and laser scanning- cytometry utilizing phospho-specific Abs, to monitor activation along these pathways in response to the reported antiaging drugs rapamycin, metformin, berberine, resveratrol, vitamin D3, 2-deoxyglucose, and acetylsalicylic acid. Specifically, effectiveness of these agents to attenuate the level of constitutive mTOR signaling was tested by cytometry and confirmed by Western blotting through measuring phosphorylation of the mTOR-downstream targets including ribosomal protein S6. The ratiometric analysis of phosphorylated to total protein along the mTOR pathway offers a useful parameter reporting the effects of gero-suppressive agents. In parallel, their ability to suppress the level of constitutive DNA damage signaling induced by endogenous ROS was measured. While the primary target of each of these agents may be different the data obtained on several human cancer cell lines, WI-38 fibroblasts and normal lymphocytes suggest common downstream mechanism in which the decline in mTOR/S6K1 signaling and translation rate is coupled with a reduction of oxidative phosphorylation and ROS that leads to decreased oxidative DNA damage. The combined assessment of constitutive γH2AX expression, mitochondrial activity (ROS, ΔΨm), and mTOR signaling provides an adequate gamut of cell responses to test effectiveness of gero-suppressive agents. Described is also an in vitro model of induction of cellular senescence by persistent replication stress, its quantitative analysis by laser scanning cytometry, and application to detect the