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mTOR Inhibitors (mtor + inhibitor)
Selected AbstractsPretreatment with insulin before ischaemia reduces infarct size in Langendorff-perfused rat heartsACTA PHYSIOLOGICA, Issue 2 2009B. N. Fuglesteg Abstract Aim:, To compare the possible role of Akt and mammalian target of rapamycin (mTOR) in mediating cardioprotection against ischaemia under three different conditions: (1) During ischaemic preconditioning (IPC), (2) when insulin was given as a pretreatment agent (InsPC) and (3) when insulin was given as a reperfusion cell survival agent (InsR). Methods:, Isolated perfused rat hearts were subjected to IPC (3 × 5 min) or InsPC (50 mU mL,1; 3 × 5 min), before 30 min of regional ischaemia followed by 120 min of reperfusion ± 1L-6-hydroxymethyl- chiro -inositol-2 - [(R)-2- O -methyl-3- O -octadecylcarbonate] (HIMO) (20 ,m; Akt inhibitor) or rapamycin (1 nm; mTOR inhibitor). In addition, insulin (3 mU mL,1) was given at the onset of reperfusion, ±HIMO or rapamycin. Risk zone (R) and infarct size (I) were determined with Evans blue and tetrazolium staining respectively. Western blot analysis was performed on tissue from Langendorff-perfused rat hearts and cell lysates from cultured HL1 cells. Results:, IPC, InsPC and InsR treatment resulted in a significant reduction in infarct size compared to controls (all P < 0.05). This protective effect of IPC and insulin was abolished by the inhibitors. However, the putative Akt inhibitor, although capable of abolishing cardioprotection induced by insulin, was not able to inhibit insulin-induced phosphorylation of Akt in Langendorff-perfused rat hearts and cultured HL1 cells. The target for this compound therefore remains to be determined. Conclusion:, IPC and insulin (either as InsPC or InsR) appear to activate mTOR, and this kinase seems to play an essential role in cardioprotection against ischaemia and reperfusion injury as rapamycin blocked the protection. [source] Noradrenaline enhances the expression of the neuronal monocarboxylate transporter MCT2 by translational activation via stimulation of PI3K/Akt and the mTOR/S6K pathwayJOURNAL OF NEUROCHEMISTRY, Issue 2 2007Julie Chenal Abstract Monocarboxylate transporter 2 (MCT2) expression is up-regulated by noradrenaline (NA) in cultured cortical neurons via a putative but undetermined translational mechanism. Western blot analysis showed that p44/p42 mitogen-activated protein kinase (MAPK) was rapidly and strongly phosphorylated by NA treatment. NA also rapidly induced serine/threonine protein kinase from AKT virus (Akt) phosphorylation but to a lesser extent than p44/p42 MAPK. However, Akt activation persisted over a longer period. Similarly, NA induced a rapid and persistent phosphorylation of mammalian target of rapamycin (mTOR), a kinase implicated in the regulation of translation in the central nervous system. Consistent with activation of the mTOR/S6 kinase pathway, phosphorylation of the ribosomal S6 protein, a component of the translation machinery, could be observed upon treatment with NA. In parallel, it was found that the NA-induced increase in MCT2 protein was almost completely blocked by LY294002 (phosphoinositide 3-kinase inhibitor) as well as by rapamycin (mTOR inhibitor), while mitogen-activated protein kinase kinase and p38 MAPK inhibitors had much smaller effects. Taken together, these data reveal that NA induces an increase in neuronal MCT2 protein expression by a mechanism involving stimulation of phosphoinositide 3-kinase/Akt and translational activation via the mTOR/S6 kinase pathway. Moreover, considering the role of NA in synaptic plasticity, alterations in MCT2 expression as described in this study might represent an adaptation to face energy demands associated with enhanced synaptic transmission. [source] Pilot study: rapamycin in advanced hepatocellular carcinomaALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2010M. Schöniger-Hekele Summary Background, The PI3K/Akt/mTOR signal pathway is involved in hepatocarcinogenesis. Rapamycin (=sirolimus), a specific mTOR inhibitor, leads to G(1) arrest of many malignant cell lines and currently, analogues of rapamycin are being investigated as a cancer chemotherapeutic adjuvant. Aim, To study the toxicity and tolerability of rapamycin therapy in patients with advanced hepatocellular carcinoma (HCC). Methods, Between June 2005 and February 2007, patients with advanced HCC, not eligible for any established therapy, were included in the study. Results, Eighteen patients (F/M: 5/13) with compensated liver cirrhosis (Child A n = 11, Child B n = 5, Child C n = 2) and histologically proven HCC were included in this study. According to the BCLC staging system, most of the patients enrolled had an advanced HCC: BCLC stage B: n = 2, Barcelona Clinic Liver-Cancer (BCLC) stage C: n = 14, BCLC stage D: n = 2. Overall, therapy with rapamycin was well tolerated. Most common toxicities were thrombocytopaenia and anaemia. We did not observe any partial or complete tumour response. At 3 months, two patients had stable disease and at 6 months, all patients had progressed. The median overall survival was 5.27 months, median time to progression was 3 months. Conclusion, Rapamycin is well tolerated in patients with advanced HCC, but only minimally effective. [source] Antiangiogenic and Immunomodulatory Effects of Rapamycin on Islet Endothelium: Relevance for Islet TransplantationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 11 2006V. Cantaluppi Donor intra-islet endothelial cells contribute to neovascularization after transplantation. Several factors may interfere with this process and ultimately influence islet engraftment. Rapamycin, a central immunosuppressant in islet transplantation, is an mTOR inhibitor that has been shown to inhibit cancer angiogenesis. The aim of this study was to evaluate the effects of rapamycin on islet endothelium. Rapamycin inhibited the outgrowth of endothelial cells from freshly purified human islets and the formation of capillary-like structures in vitro and in vivo after subcutaneous injection within Matrigel plugs into SCID mice. Rapamycin decreased migration, proliferation and angiogenic properties of human and mouse islet-derived endothelial cell lines with appearance of apoptosis. The expression of angionesis-related factors VEGF, ,V,3 integrin and thrombospondin-1 on islet endothelium was altered in the presence of rapamycin. On the other hand, rapamycin decreased the surface expression of molecules involved in immune processes such as ICAM-1 and CD40 and reduced the adhesion of T cells to islet endothelium. Our results suggest that rapamycin exerts dual effects on islet endothelium inducing a simultaneous inhibition of angiogenesis and a down-regulation of receptors involved in lymphocyte adhesion and activation. [source] Targeted inhibition of mammalian target of rapamycin for the treatment of advanced renal cell carcinomaCANCER, Issue 16 2009Anil Kapoor MD Abstract Clinical trials have validated the importance of mammalian target of rapamycin (mTOR) as a targeted mechanism in the treatment of renal cell carcinoma (RCC). Temsirolimus, an mTOR inhibitor that is approved for treatment of advanced RCC, has demonstrated both overall survival benefits and progression-free survival benefits versus interferon,, as first-line treatment for patients with poor prognostic features. Exploratory subset analyses indicated that temsirolimus benefits patients with RCC regardless of tumor histology or nephrectomy status. Everolimus, the second mTOR inhibitor to demonstrate activity in RCC, improved progression-free survival versus placebo in patients whose disease progressed after treatment with vascular endothelial growth factor receptor tyrosine kinase inhibitors (sunitinib, sorafenib, or both); benefit was observed for all risk groups. Deforolimus also exhibited antitumor activity against RCC in early clinical studies. There is now compelling clinical evidence for the effectiveness of targeting mTOR in the treatment of RCC. Cancer 2009. © 2009 American Cancer Society. [source] Short-period hypoxia increases mouse embryonic stem cell proliferation through cooperation of arachidonic acid and PI3K/Akt signalling pathwaysCELL PROLIFERATION, Issue 2 2008S. H. Lee Hypoxia plays important roles in some early stages of mammalian embryonic development and in various physiological functions. This study examined the effect of arachidonic acid on short-period hypoxia-induced regulation of G1 phase cell-cycle progression and inter-relationships among possible signalling molecules in mouse embryonic stem cells. Hypoxia increased the level of hypoxia-inducible factor-1, (HIF-1,) expression and H2O2 generation in a time-dependent manner. In addition, hypoxia increased the levels of cell-cycle regulatory proteins (cyclin D1, cyclin E, cyclin-dependent kinase 2 (CDK2) and CDK4). Maximum increases in the level of these proteins and retinoblastoma phosphorylation were observed after 12,24 h of exposure to hypoxic conditions, and then decreased. Alternatively, the level of the CDK inhibitors, p21Cip1 and p27Kip1 were decreased. These results were consistent with the results of [3H]-thymidine incorporation and cell counting. Hypoxia also increased the level of [3H]-arachidonic acid release and inhibition of cPLA2 reduced hypoxia-induced increase in levels of the cell-cycle regulatory proteins and [3H]-thymidine incorporation. The level of cyclooxygenase-2 (COX-2) was also increased by hypoxia and inhibition of COX-2 decreased the levels of cell-cycle regulatory proteins and [3H]-thymidine incorporation. Indeed, the percentage of cells in S phase, levels of cell cycle regulatory proteins, and [3H]-thymidine incorporation were further increased in hypoxic conditions with arachidonic acid treatment compared to normoxic conditions. Hypoxia-induced Akt and mitogen-activated protein kinase (MAPK) phosphorylation was inhibited by vitamin C (antioxidant, 10,3 M). In addition, hypoxia-induced increase of cell-cycle regulatory protein expression and [3H]-thymidine incorporation were attenuated by LY294002 (PI3K inhibitor, 10,6 M), Akt inhibitor (10,6 M), rapamycin (mTOR inhibitor, 10,9 M), PD98059 (p44/42 inhibitor, 10,5 M), and SB203580 (p38 MAPK inhibitor, 10,6 M). Furthermore, hypoxia-induced increase of [3H]-arachidonic acid release was blocked by PD98059 or SB203580, but not by LY294002 or Akt inhibitor. In conclusion, arachidonic acid up-regulates short time-period hypoxia-induced G1 phase cyclins D1 and E, and CDK 2 and 4, in mouse embryonic stem cells through the cooperation of PI3K/Akt/mTOR, MAPK and cPLA2 -mediated signal pathways. [source] Severe aphthous stomatitis associated with oral calcineurin and mTOR inhibitorsINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 1 2010Nancy Habib BS Background, Aphthous stomatitis, a common mucocutaneous disorder, is a well accepted complication of sirolimus therapy. This association has been reported less frequently with tacrolimus. Case, We present an 11-year old male with Budd-Chiari syndrome who experienced profound worsening of chronic aphthous ulcers after immunosuppressive therapy was changed from tacrolimus to sirolimus. Conclusion, Since these drugs are used widely in the pediatric transplantation population, this report serves to heighten awareness of this debilitating phenomenon, and to stress the importance of exercising caution when sirolimus and tacrolimus are administered in combination to pediatric patients. [source] Sorafenib and rapamycin induce growth suppression in mouse models of hepatocellular carcinomaJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 8b 2009Hung Huynh Abstract Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide. Vascular endothelial growth factor, platelet derived growth factor and the Raf/mitogen-activated protein kinase/extracellular signal regulated kinase (Raf/MEK/ERK) signalling pathway regulates the growth, neovascularization, invasiveness and metastatic potential of HCC. In this study, we investigated the in vivo antitumour activity and mechanisms of action of sorafenib tosylate on four patient-derived HCC xenografts. Sorafenib dosed at 50 mg/kg and 100 mg/kg inhibited tumour growth by 85% and 96%, respectively. Sorafenib-induced growth suppression and apoptosis were associated with inhibition of angiogenesis, down-regulation of phospho-platelet-derived growth factor receptor , Tyr1021, phospho-eIF4E Ser209, phospho-c-Raf Ser259, c-Raf, Mcl-1, Bcl-2, Bcl-x and positive cell cycle regulators, up-regulation of apoptosis signalling kinase-1, p27 and p21. Expression of IGF-1R, and phosphorylation of c-Raf Ser338, MEK1/2 Ser217/221 and ERK1/2 Thr202/Tyr204 were increased by sorafenib treatment. Phosphorylation of mammalian target-of-rapamycin (mTOR) targets (p70S6K, S6R and 4EBP1) was reduced by sorafenib in sorafenib-sensitive lines but activated in sorafenib-less-sensitive 10,0505 xenograft. Sorafenib-induced phosphorylation of c-met, p70S6K and 4EBP1 was significantly reduced when 10,0505 cells were co-treated with anti-human anti-HGF antibody, suggesting that treatment with sorafenib leads to increased HGF secretion and activation of c-met and mTOR targets. Treatment of 10,0505 tumours with sorafenib plus rapamycin resulted in growth inhibition, inhibition of vascular endothelial growth factor receptor-2 phosphorylation, increased apoptosis and completely blocked sorafenib-induced phosphorylation of mTOR targets and cyclin B1 expression. These data also provide a strong rationale for clinical investigation of sorafenib in combination with mTOR inhibitors in patients with HCC. [source] What can we learn from tuberous sclerosis complex (TSC) about autism?JOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 10 2008P. J. De Vries Tuberous Sclerosis Complex (TSC) is now recognized as one of the medical conditions most commonly associated with autism. Between 1,5% of those with autism have TSC and up to 50% of people with TSC meet criteria for an autism spectrum disorder. The clinical characteristics of autism in TSC are qualitatively indistinguishable from those of idiopathic autism. So, what can TSC teach us about autism? We will present an overview of the neuropsychiatric features of TSC and will proceed with an examination of aetiological models of autism in TSC. Structural models (suggesting that autism is caused by brain lesions in specific neuroanatomical locations) and seizure models (suggesting that the age, type and control of seizures may predict autism) have both received some support, but with limited replication. More recently, molecular approaches have suggested that dysregulation of intracellular signalling through the TSC1/2-mTOR pathway may be sufficient to lead to socialization deficits and autism, and that drugs that act as mTOR inhibitors may reverse some aspects of the learning and social deficits in TSC. [source] Rapamycin and CCI-779 inhibit the mammalian target of rapamycin signalling in hepatocellular carcinomaLIVER INTERNATIONAL, Issue 1 2010Ivan Chun-Fai Hui Abstract Background: The mammalian target of rapamycin (mTOR), which phosphorylates p70S6K and 4EBP1 and activates the protein translation process, is upregulated in cancers and its activation may be involved in cancer development. Aims: In this study, we investigated the tumour-suppressive effects of rapamycin and its new analogue CCI-779 on hepatocellular carcinoma (HCC). Methods: Rapamycin and its new analogue CCI-779 were applied to treat HCC cells. Cell proliferation, cell cycle profile and tumorigenicity were analysed. Results: In human HCCs, we observed frequent (67%, 37/55) overexpression of mTOR transcripts using real-time reverse transcriptase-polymerase chain reaction. Upon drug treatment, PLC/PRF/5 showed the greatest reduction in cell proliferation using the colony formation assay, as compared with HepG2, Hep3B and HLE. Rapamycin was a more potent antiproliferative agent than CCI-779 in HCC cell lines. Proliferation assays by cell counting showed that the IC50 value of rapamycin was lower than that of CCI-779 in PLC/PRF/5 cells. Furthermore, flow cytometric analysis showed that both drugs could arrest HCC cells in the G1 phase but did not induce apoptosis of these cells, suggesting that these mTOR inhibitors are cytostatic rather than cytotoxic. Upon rapamycin and CCI-779 treatment, the phosphorylation level of mTOR and p70S6K in HCC cell lines was significantly reduced, indicating that both drugs can suppress mTOR activity in HCC cells. In addition, both drugs significantly inhibited the growth of xenografts of PLC/PRF/5 cells in nude mice. Conclusions: Our findings indicate that rapamycin and its clinical analogue CCI-779 possess tumour-suppressive functions towards HCC cells. [source] mTOR inhibitors: An overviewLIVER TRANSPLANTATION, Issue 6 2001Peter Neuhaus MD Inhibitors of the mammalian target of rapamycin are a new class of immunosuppressants. In contrast to other macrolides, such as tacrolimus and cyclosporine A, they do not inhibit calcineurin and thus signal I of T-cell activation. By inhibiting signal III, the mechanism of action and side effects of sirolimus (rapamycin) and its derivative RAD are distinct from other immunosuppressants. Reports of synergism with cyclosporine A and tacrolimus in preclinical and clinical studies, avoidance of nephrotoxicity, and possible treatment or prevention of chronic allograft rejection are leading to high expectations for this new class of immunosuppressants. Furthermore, studies evaluating tolerance induction are being conducted. This review summarizes preclinical and clinical results published to date and exploits the future value of sirolimus and RAD for clinical transplantation. [source] Renal Failure Five Years After Lung Transplantation Due to Polyomavirus BK-Associated NephropathyAMERICAN JOURNAL OF TRANSPLANTATION, Issue 10 2010A. Egli Polyomavirus-associated nephropathy (PyVAN) is rare in nonrenal solid organ transplantation and only limited information is available from single cases. We describe a 67-year-old female presenting with hypertension and progressive kidney failure due to PyVAN 60 months after lung transplantation. Plasma BK virus (BKV) loads were 4.85 log10 copies/mL at diagnosis and cleared slowly over 14 months after switching from tacrolimus, mycophenolate and prednisone to low-dose tacrolimus, sirolimus and leflunomide, the latter being discontinued for anemia and diarrhea. BKV- and JC virus-specific immunoglobulins were detectable prior to transplantation. Only BKV-specific IgG and IgM increased during follow-up. BKV-specific T cells were detectable in blood following in vitro expansion, but cleared with reincreased sirolimus, yet BKV viremia remained undetectable. We identified eight other cases of PyVAN in nonrenal solid organ transplantation including lung (n = 1), heart (n = 6) and pancreas (n = 1). Overall, diagnosis was later than commonly seen in kidney transplants (median 18 months, interquartile range 10,29). Seven patients were male, five received triple immunosuppression consisting of tacrolimus, mycophenolate, prednisone. Immunosuppression was reduced in four cases and cidofovir and/or leflunomide administered in five and two cases, respectively. Renal function deteriorated in five requiring hemodialysis in four. We discuss mTOR inhibitors versus cidofovir and leflunomide as potential PyVAN rescue therapy. [source] The Multifunctional Role of mTOR in Innate Immunity: Implications for Transplant ImmunityAMERICAN JOURNAL OF TRANSPLANTATION, Issue 12 2009M. D. Säemann The mammalian target of rapamycin (mTOR) is an evolutionary conserved serine,threonine kinase that senses various environmental stimuli in most cells primarily to control cell growth. Restriction of cellular proliferation by mTOR inhibition led to the use of mTOR inhibitors as immunosuppressants in allogeneic transplantation as well as novel anticancer agents. However, distinct inflammatory side effects such as fever, pneumonitis, glomerulonephritis or anemia of chronic disease have been observed under this treatment regime. Apart from the mere cell-cycle regulatory effect of mTOR in dividing cells, recent data revealed a master regulatory role of mTOR in the innate immune system. Hence, inhibition of mTOR promotes proinflammatory cytokines such as IL-12 and IL-1,, inhibits the anti-inflammatory cytokine IL-10 and boosts MHC antigen presentation via autophagy in monocytes/macrophages and dendritic cells. Moreover, mTOR regulates type I interferon production and the expression of chemokine receptors and costimulatory molecules. These results place mTOR in a complex immunoregulatory context by controlling innate and adaptive immune responses. In this review, we discuss the clinical consequences of mTOR-inhibitor therapy and aim to integrate this recent data into our current view of the molecular mechanisms of clinically employed mTOR inhibitors and discuss their relevance with special emphasis to transplantation. [source] Mammalian Target of Rapamycin Inhibitor Dyslipidemia in Kidney Transplant RecipientsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 7 2008B. L. Kasiske The incidence, pathogenesis, consequences and treatment of mammalian target of rapamycin (mTOR) inhibitor dyslipidemia are not well described. We conducted a systematic review of randomized controlled trials reporting cholesterol and triglycerides in mTOR versus non-mTOR inhibitor immunosuppressive treatment regimens in kidney transplant recipients. All but one of 17 trials reported higher levels of cholesterol and triglycerides, or an increased prevalence of treatment with lipid-lowering agents. Approximately 60% of mTOR inhibitor-treated patients received lipid-lowering agents (2-fold higher than controls). There appeared to be little difference between dyslipidemias caused by sirolimus (14 trials) versus everolimus (3 trials). It was difficult to determine the extent to which declines in lipids over time posttransplant were due to lipid-lowering therapy, changes in doses and/or discontinuations of mTOR inhibitors. From the four trials that measured lipoproteins, it appeared that at least some of the increase in total cholesterol with mTOR inhibitors was due to increased low-density lipoprotein cholesterol. What direct or indirect effects mTOR inhibitors have on atherosclerotic cardiovascular disease in kidney transplant patients are unknown. However, in the absence of the necessary clinical trials, dyslipidemia should be managed, as it would be in nontransplant patients at high risk for cardiovascular disease. [source] Mammalian target of rapamycin signaling is crucial for joint destruction in experimental arthritis and is activated in osteoclasts from patients with rheumatoid arthritisARTHRITIS & RHEUMATISM, Issue 8 2010Daniel Cejka Objective Activation of the mammalian target of rapamycin (mTOR) pathway is important for immune cell activation and bone metabolism. To date, the contribution of mTOR signaling to joint inflammation and structural bone and cartilage damage is unknown. The aim of this study was to investigate the potential of inhibiting mTOR as a treatment of inflammatory arthritis. Methods Human tumor necrosis factor,transgenic mice in which inflammatory arthritis was developing were treated with 2 different mTOR inhibitors, sirolimus or everolimus. The effects of treatment on clinical disease activity, inflammation, and localized joint and cartilage destruction were studied. In addition, the effects of mTOR inhibition on osteoclast survival and expression of key molecules of osteoclast function were analyzed in vitro. Moreover, synovial tissue from patients with rheumatoid arthritis (RA) was assessed for activation of the mTOR pathway. Results Inhibition of mTOR by sirolimus or everolimus reduced synovial osteoclast formation and protected against local bone erosions and cartilage loss. Clinical signs of arthritis improved after mTOR inhibition, and histologic evaluation showed a decrease in synovitis. In vitro, mTOR inhibition down-regulated the expression of digestive enzymes and led to osteoclast apoptosis. Moreover, mTOR signaling was shown to be active in the synovial membrane of patients with RA, particularly in synovial osteoclasts. Conclusion Signaling through mTOR is an important link between synovitis and structural damage in inflammatory arthritis. Current pharmacologic inhibitors of mTOR could be effective in protecting joints against structural damage. [source] Angiomyolipomata: challenges, solutions, and future prospects based on over 100 cases treatedBJU INTERNATIONAL, Issue 1 2010Prasanna Sooriakumaran Study Type , Therapy (case series) Level of Evidence 4 OBJECTIVE To examine the presentation, management and outcomes of patients with renal angiomyolipoma (AML) over a period of 10 years, at St George's Hospital, London, UK. PATIENTS AND METHODS We assessed retrospectively 102 patients (median follow-up 4 years) at our centre; 70 had tuberous sclerosis complex (TSC; median tumour size 3.5 cm) and the other 32 were sporadic (median tumour size 1.2 cm). Data were gathered from several sources, including radiology and clinical genetics databases. The 77 patients with stable disease were followed up with surveillance imaging, and 25 received interventions, some more than one. Indications for intervention included spontaneous life-threatening haemorrhage, large AML (10,20 cm), pain and visceral compressive symptoms. RESULTS Selective arterial embolization (SAE) was performed in 19 patients; 10 received operative management and four had a radiofrequency ablation (RFA). SAE was effective in controlling haemorrhage from AMLs in the acute setting (six) but some patients required further intervention (four) and there was a significant complication rate. The reduction in tumour volume was only modest (28%). No complications occurred after surgery (median follow-up 5.5 years) or RFA (median follow-up 9 months). One patient was entered into a trial and treated with sirolimus (rapamycin). CONCLUSIONS The management of AML is both complex and challenging, especially in those with TSC, where tumours are usually larger and multiple. Although SAE was effective at controlling haemorrhage in the acute setting it was deemed to be of limited value in the longer term management of these tumours. Thus novel techniques such as focused ablation and pharmacological therapies including the use of anti-angiogenic molecules and mTOR inhibitors, which might prove to be safer and equally effective, should be further explored. [source] | |||||||||||||