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Saccharomyces cerevisiae adapted to grow in the presence of low-dose rapamycin exhibit altered amino acid metabolism.
Dikicioglu, D, Dereli Eke, E, Eraslan, S, Oliver, SG, Kirdar, B
Cell communication and signaling : CCS. 2018;(1):85
Abstract
BACKGROUND Rapamycin is a potent inhibitor of the highly conserved TOR kinase, the nutrient-sensitive controller of growth and aging. It has been utilised as a chemotherapeutic agent due to its anti-proliferative properties and as an immunosuppressive drug, and is also known to extend lifespan in a range of eukaryotes from yeast to mammals. However, the mechanisms through which eukaryotic cells adapt to sustained exposure to rapamycin have not yet been thoroughly investigated. METHODS Here, S. cerevisiae response to long-term rapamycin exposure was investigated by identifying the physiological, transcriptomic and metabolic differences observed for yeast populations inoculated into low-dose rapamycin-containing environment. The effect of oxygen availability and acidity of extracellular environment on this response was further deliberated by controlling or monitoring the dissolved oxygen level and pH of the culture. RESULTS Yeast populations grown in the presence of rapamycin reached higher cell densities complemented by an increase in their chronological lifespan, and these physiological adaptations were associated with a rewiring of the amino acid metabolism, particularly that of arginine. The ability to synthesise amino acids emerges as the key factor leading to the major mechanistic differences between mammalian and microbial TOR signalling pathways in relation to nutrient recognition. CONCLUSION Oxygen levels and extracellular acidity of the culture were observed to conjointly affect yeast populations, virtually acting as coupled physiological effectors; cells were best adapted when maximal oxygenation of the culture was maintained in slightly acidic pH, any deviation necessitated more extensive readjustment to additional stress factors.
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Treatment of Lymphatic Malformations with the mTOR Inhibitor Sirolimus: A Systematic Review.
Wiegand, S, Wichmann, G, Dietz, A
Lymphatic research and biology. 2018;(4):330-339
Abstract
BACKGROUND Extensive lymphatic malformations are low-flow vascular malformations that can cause devastating complications. Treatment of these malformations is challenging. This systematic review presents current use of sirolimus in patients with extensive lymphatic malformations. METHODS MEDLINE and Google scholar search was conducted for studies on sirolimus treatment of lymphatic malformations up to July 2017. Search items included "lymphatic malformation," "lymphangioma," "cystic hygroma," "vascular malformation," "low-flow malformation," "sirolimus," "rapamycin," and "mTOR inhibitor." RESULTS Twenty studies, including 71 patients receiving sirolimus, were included into this review. Forty-five patients had lymphatic malformations, eight patients venolymphatic malformations, and 19 patients capillary-lymphatico-venous malformations. Sirolimus led to a partial remission of disease in 60 patients, three patients had a progressive disease, and the outcome of eight patients was not reported. Dosing, target trough level, and duration of treatment differed between the studies. Common adverse effects were hyperlipidemia and neutropenia. CONCLUSIONS Available literature indicated that sirolimus therapy might be effective for lymphatic malformations. However, further randomized controlled studies are required to analyze the efficacy and long-term adverse events and to clarify the potential role for sirolimus in the management of lymphatic malformations.
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Insulin-mimetic effects of short-term rapamycin in type 1 diabetic patients prior to islet transplantation.
Benedini, S, Ermetici, F, Briganti, S, Codella, R, Terruzzi, I, Maffi, P, Caldara, R, Secchi, A, Nano, R, Piemonti, L, et al
Acta diabetologica. 2018;(7):715-722
Abstract
BACKGROUND The immunosuppressive drug rapamycin may influence insulin sensitivity in insulin-responsive tissues. AIMS This study aimed at evaluating the effectiveness of rapamycin pre-treatment before pancreatic islet allotransplantation (ITx) in patients with type 1 diabetes mellitus (T1DM). METHODS Forty-one T1DM patients were studied. Thirteen patients with poor glycemic control underwent a short-term rapamycin treatment before ITx (Group 1), and they were compared to 28 patients undergoing ITx without rapamycin pre-treatment (Group 2). Outcomes were daily insulin requirement (DIR), fasting blood glucose, HbA1c, C-peptide and the SUITO index of beta-cell function. A subgroup of patients pre-treated with rapamycin before ITx underwent euglycemic hyperinsulinemic clamp with [6,6-2H2] glucose before and after ITx to evaluate insulin sensitivity. RESULTS We found a significant reduction in DIR after rapamycin pre-treatment (- 8 ± 6 U/day, mean ± SD, p < 0.001) and 1 year after ITx. DIR reduction 1 year after ITx was greater in Group 1 as compared to Group 2 (- 37 ± 15 vs. - 19 ± 13 U/day, p = 0.005) and remained significant after adjusting for gender, age, glucose and baseline HbA1c (beta = 18.2 ± 5.9, p = 0.006). Fasting glucose and HbA1c significantly decreased 1 year after ITx in Group 1 (HbA1c: - 2.1 ± 1.4%, p = 0.002), while fasting C-peptide (+0.5 ± 0.3 nmol/l, p = 0.002) and SUITO index increased (+57.4 ± 39.7, p = 0.016), without differences between the two groups. Hepatic glucose production decreased after rapamycin pre-treatment (- 1.1 ± 1.1 mg/kg/min, p = 0.04) and after ITx (- 1.6 ± 0.6 mg/kg/min, p = 0.015), while no changes in peripheral glucose disposal were observed. CONCLUSIONS Rapamycin pre-treatment before ITx succeeds in reducing insulin requirement, enhancing hepatic insulin sensitivity. This treatment may improve short-term ITx outcomes, possibly in selected patients with T1DM complicated by insulin resistance. CLINICAL TRIAL Clinicaltrials.gov NCT01060605; NCT00014911.
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Sirolimus in patients with clinically active systemic lupus erythematosus resistant to, or intolerant of, conventional medications: a single-arm, open-label, phase 1/2 trial.
Lai, ZW, Kelly, R, Winans, T, Marchena, I, Shadakshari, A, Yu, J, Dawood, M, Garcia, R, Tily, H, Francis, L, et al
Lancet (London, England). 2018;(10126):1186-1196
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Abstract
BACKGROUND Patients with systemic lupus erythematosus have T-cell dysfunction that has been attributed to the activation of the mammalian target of rapamycin (mTOR). Rapamycin inhibits antigen-induced T-cell proliferation and has been developed as a medication under the generic designation of sirolimus. We assessed safety, tolerance, and efficacy of sirolimus in a prospective, biomarker-driven, open-label clinical trial. METHODS We did a single-arm, open-label, phase 1/2 trial of sirolimus in patients with active systemic lupus erythematosus disease unresponsive to, or intolerant of, conventional medications at the State University of New York Upstate Medical University (Syracuse, NY, USA). Eligible participants (aged ≥18 years) had active systemic lupus erythematosus fulfilling four or more of 11 diagnostic criteria defined by the American College of Rheumatology. We excluded patients with allergy or intolerance to sirolimus, patients with life-threatening manifestations of systemic lupus erythematosus, proteinuria, a urine protein to creatinine ratio higher than 0·5, anaemia, leucopenia, or thrombocytopenia. Patients received oral sirolimus at a starting dose of 2 mg per day, with dose adjusted according to tolerance and to maintain a therapeutic range of 6-15 ng/mL. Patients were treated with sirolimus for 12 months. Safety outcomes included tolerance as assessed by the occurrence of common side-effects. The primary efficacy endpoint was decrease in disease activity, assessed using the British Isles Lupus Assessment Group (BILAG) index and the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). Blood samples of 56 matched healthy individuals were obtained as controls for immunobiological outcomes monitored at each visit. The primary efficacy endpoint was assessed in all patients who completed 12 months of treatment, and all patients who received at least one dose of treatment were included in the safety analyses. This trial is registered with ClinicalTrials.gov, number NCT00779194. FINDINGS Between March 9, 2009, and Dec 8, 2014, 43 patients were enrolled, three of whom did not meet eligibility criteria. 11 of the 40 eligible patients discontinued study treatment because of intolerance (n=2) or non-compliance (n=9). SLEDAI and BILAG disease activity scores were reduced during 12 months of treatment in 16 (55%) of 29 patients who completed treatment. Mean SLEDAI score decreased from 10·2 (SD 5·6) at enrolment to 4·8 (4·5) after 12 months of treatment (p<0·001) and the mean total BILAG index score decreased from 28·4 (12·4) at enrolment to 17·4 (10·7) after 12 months of treatment (p<0·001). The mean daily dose of prednisone required to control disease activity decreased from 23·7 mg (SD 9·6) to 7·2 mg (2·3; p<0·001) after 12 months of treatment. Sirolimus expanded CD4+CD25+FoxP3+ regulatory T cells and CD8+ memory T-cell populations and inhibited interleukin-4 and interleukin-17 production by CD4+ and CD4-CD8- double-negative T cells after 12 months. CD8+ memory T cells were selectively expanded in SRI-responders. Patient liver function and lymphocyte counts were unchanged. Although HDL-cholesterol (Z=-2·50, p=0·012), neutrophil counts (Z=-1·92, p=0·054), and haemoglobin (Z=-2·83, p=0·005) were moderately reduced during treatment, all changes occurred within a range that was considered safe. Platelet counts were slightly elevated during treatment (Z=2·06, p=0·0400). INTERPRETATION These data show that a progressive improvement in disease activity is associated with correction of pro-inflammatory T-cell lineage specification in patients with active systemic lupus erythematosus during 12 months of sirolimus treatment. Follow-up placebo-controlled clinical trials in diverse patient populations are warranted to further define the role of mTOR blockade in treatment of systemic lupus erythematosus. FUNDING Pfizer, the National Institutes of Health, and the Central New York Community Foundation.
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Ultrathin-strut, biodegradable-polymer, sirolimus-eluting stents versus thin-strut, durable-polymer, everolimus-eluting stents for percutaneous coronary revascularisation: 5-year outcomes of the BIOSCIENCE randomised trial.
Pilgrim, T, Piccolo, R, Heg, D, Roffi, M, Tüller, D, Muller, O, Moarof, I, Siontis, GCM, Cook, S, Weilenmann, D, et al
Lancet (London, England). 2018;(10149):737-746
Abstract
BACKGROUND Drug-eluting stents combining an ultrathin cobalt-chromium stent platform with a biodegradable polymer eluting sirolimus have been shown to be non-inferior or superior to thin-strut, durable-polymer, everolimus-eluting stents in terms of 1 year safety and efficacy outcomes. METHODS In the randomised, single-blind, multicentre, non-inferiority BIOSCIENCE trial, we compared biodegradable-polymer sirolimus-eluting stents with durable-polymer everolimus-eluting stents in patients with chronic stable coronary artery disease or acute coronary syndromes. Here, we assess the final 5-year clinical outcomes of BIOSCIENCE with regards to the primary clinical outcome of target lesion failure, which was a composite of cardiac death, target vessel myocardial infarction, and clinically indicated target lesion revascularisation. The primary analysis was done by intention to treat. The BIOSCIENCE trial is registered with ClinicalTrials.gov, number NCT01443104. FINDINGS 2008 (95%) of 2119 patients recruited between March 1, 2012, and May 31, 2013, completed 5 years of follow-up. Target lesion failure occurred in 198 patients (cumulative incidence 20·2%) treated with biodegradable-polymer sirolimus-eluting stents and in 189 patients (18·8%) treated with durable-polymer everolimus-eluting stents (rate ratio [RR] 1·07, 95% CI 0·88-1·31; p=0·487). All-cause mortality was significantly higher in patients treated with biodegradable-polymer sirolimus-eluting stents than in those treated with durable-polymer everolimus-eluting stents (14·1% vs 10·3%; RR 1·36, 95% CI 1·06-1·75; p=0·017), driven by a difference in non-cardiovascular deaths. We observed no difference between groups in cumulative incidence of definite stent thrombosis at 5 years (1·6% in both groups; 1·02, 0·51-2·05; p=0·950). INTERPRETATION 5-year risk of target lesion failure among all-comer patients undergoing percutaneous coronary intervention is similar after implantation of ultrathin-strut, biodegradable-polymer, sirolimus-eluting stents or thin-strut, durable-polymer, everolimus-eluting stents. Higher incidences of all-cause and non-cardiovascular mortality in patients treated with biodegradable-polymer stents eluting sirolimus than in those treated with durable-polymer stents eluting everolimus warrant careful observation in ongoing clinical trials. FUNDING Clinical Trials Unit of the University of Bern and Biotronik.
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Safety and efficacy of a bioabsorbable polymer-coated, everolimus-eluting coronary stent in patients with diabetes: the EVOLVE II diabetes substudy.
Kereiakes, DJ, Meredith, IT, Masotti, M, Carrié, D, Moreno, R, Erglis, A, Mehta, SR, Elhadad, S, Berland, J, Stein, B, et al
EuroIntervention : journal of EuroPCR in collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology. 2017;(16):1987-1994
Abstract
AIMS: Bioabsorbable polymer drug-eluting stents (DES) may reduce the inflammation and delayed healing associated with some permanent polymer-coated DES. Whether late clinical outcomes are improved, particularly among patients with medically treated diabetes, is unknown. Therefore, we analysed outcomes from a pre-specified substudy of the EVOLVE II trial to evaluate the safety and effectiveness of the SYNERGY stent in patients with diabetes mellitus. METHODS AND RESULTS SYNERGY is a thin-strut, platinum-chromium everolimus-eluting stent with an ultra-thin bioabsorbable poly(DL-lactide-co-glycolide) abluminal polymer. The EVOLVE II randomised, controlled trial proved the non-inferiority of the SYNERGY versus the PROMUS Element Plus stent for one-year target lesion failure (TLF: ischaemia-driven target lesion revascularisation [ID-TLR], target vessel myocardial infarction [TVMI], or cardiac death). The pre-specified EVOLVE II diabetes substudy prospectively pooled randomised patients with diabetes (N=263) with a sequential single-arm diabetic cohort (n=203). The substudy primary endpoint was one-year TLF compared with a pre-specified performance goal (14.5%). The primary endpoint occurred in 7.5% of SYNERGY-treated patients with diabetes, significantly less than the performance goal (p<0.0001). The two-year rate of TLF was 11.2% (cardiac death 1.5%, TVMI 6.4%, ID-TLR 6.8%) and definite/probable stent thrombosis occurred in 1.1% of patients. CONCLUSIONS The EVOLVE II diabetes substudy demonstrates the efficacy and safety of the SYNERGY stent in patients with medically treated diabetes.
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Orsiro cobalt-chromium sirolimus-eluting stent: present and future perspectives.
Iglesias, JF, Roffi, M, Degrauwe, S, Secco, GG, Aminian, A, Windecker, S, Pilgrim, T
Expert review of medical devices. 2017;(10):773-788
Abstract
New-generation drug-eluting stents (DES) represent the current standard of care in patients undergoing percutaneous coronary intervention (PCI). Biodegradable polymer DES (BP-DES) were recently developed to overcome current limitations of newer-generation durable polymer DES (DP-DES) attributed to sustained inflammatory responses induced by permanent polymers. The Orsiro DES (Biotronik AG, Bülach, Switzerland) is a novel thin-strut cobalt-chromium sirolimus-eluting stent with biodegradable polymer that features some of the latest developments in DES technology. Areas covered: This article aims to review the currently available evidence on the clinical performance of the Orsiro BP-DES and its future perspectives. Expert commentary: The Orsiro DES is a recent newer-generation BP-DES that combines a highly deliverable thin-strut cobalt-chromium stent platform and a unique hybrid concept with passive and active coatings designed to enhance tissue biocompatibility. In preclinical and intravascular imaging studies, the Orsiro BP-DES was shown to induce low inflammation and promote very early arterial healing. Recently, large randomized non-inferiority clinical trials have shown similar short- and mid-term efficacy and safety outcomes with Orsiro BP-DES compared with currently established newer-generation DES among all-comers and high-risk subgroups. The potential clinical superiority of Orsiro BP-DES over Xience DP-DES in patients with STEMI is currently investigated in the BIOSTEMI trial (NCT02579031).
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Modulation of nonsense mediated decay by rapamycin.
Martinez-Nunez, RT, Wallace, A, Coyne, D, Jansson, L, Rush, M, Ennajdaoui, H, Katzman, S, Bailey, J, Deinhardt, K, Sanchez-Elsner, T, et al
Nucleic acids research. 2017;(6):3448-3459
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Abstract
Rapamycin is a naturally occurring macrolide whose target is at the core of nutrient and stress regulation in a wide range of species. Despite well-established roles as an inhibitor of cap-dependent mRNA translation, relatively little is known about its effects on other modes of RNA processing. Here, we characterize the landscape of rapamycin-induced post-transcriptional gene regulation. Transcriptome analysis of rapamycin-treated cells reveals genome-wide changes in alternative mRNA splicing and pronounced changes in NMD-sensitive isoforms. We demonstrate that despite well-documented attenuation of cap-dependent mRNA translation, rapamycin can augment NMD of certain transcripts. Rapamycin-treatment significantly reduces the levels of both endogenous and exogenous Premature Termination Codon (PTC)-containing mRNA isoforms and its effects are dose-, UPF1- and 4EBP-dependent. The PTC-containing SRSF6 transcript exhibits a shorter half-life upon rapamycin-treatment as compared to the non-PTC isoform. Rapamycin-treatment also causes depletion of PTC-containing mRNA isoforms from polyribosomes, underscoring the functional relationship between translation and NMD. Enhanced NMD activity also correlates with an enrichment of the nuclear Cap Binding Complex (CBC) in rapamycin-treated cells. Our data demonstrate that rapamycin modulates global RNA homeostasis by NMD.
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One-year outcomes of a BioMime™ Sirolimus-Eluting Coronary Stent System with a biodegradable polymer in all-comers coronary artery disease patients: The meriT-3 study.
Jain, RK, Chakravarthi, P, Shetty, R, Ramchandra, P, Polavarapu, RS, Wander, GS, Mohan, B, Banker, DN, Dharmadhikari, A, Bansal, SS, et al
Indian heart journal. 2016;(5):599-603
Abstract
OBJECTIVES The aim of the merit-3 study was to determine the safety and performance of the BioMime Sirolimus-Eluting Coronary Stent System (SES) in all-comer patients with coronary artery disease (CAD) in one-year clinical follow-up period. METHODS The meriT-3 was a multi-centre, observational, post-marketing study conducted in 1161 patients with CAD who were implanted with BioMime SES at 15 sites in India. The primary endpoint was major adverse cardiac event (MACE) at one year defined as the composite of cardiac death, myocardial infarction (MI) and target lesion revascularization (TLR). Clinical follow-up was performed at 1, 6, and 12 months. Major adverse cardiac event occurred at 30 days and subsequently at 6 months and at long-term follow-up of 1 year was analyzed. RESULTS MACE observed at 1 and 6 months follow-up was 16 (1.38%) and 21 (1.83%) respectively. Cumulative 1 year MACE was 26 (2.35%) with 16 (1.39%) all cause death, 4 (0.35%) MI and 6 (0.52%) TLR. In addition, ST was observed in 1 (0.09%) patient. CONCLUSIONS The present study suggests that the BioMime SES is safe and effective in a "real-world", all-comers CAD patients, indicating low rates of MACE. CTRI ACKNOWLEDGEMENT NO REF/2016/07/011808.
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Target of Rapamycin (TOR) Regulates Growth in Response to Nutritional Signals.
Weisman, R
Microbiology spectrum. 2016;(5)
Abstract
All organisms can respond to the availability of nutrients by regulating their metabolism, growth, and cell division. Central to the regulation of growth in response to nutrient availability is the target of rapamycin (TOR) signaling that is composed of two structurally distinct complexes: TOR complex 1 (TORC1) and TOR complex 2 (TORC2). The TOR genes were first identified in yeast as target of rapamycin, a natural product of a soil bacterium, which proved beneficial as an immunosuppressive and anticancer drug and is currently being tested for a handful of other pathological conditions including diabetes, neurodegeneration, and age-related diseases. Studies of the TOR pathway unraveled a complex growth-regulating network. TOR regulates nutrient uptake, transcription, protein synthesis and degradation, as well as metabolic pathways, in a coordinated manner that ensures that cells grow or cease growth in response to nutrient availability. The identification of specific signals and mechanisms that stimulate TOR signaling is an active and exciting field of research that has already identified nitrogen and amino acids as key regulators of TORC1 activity. The signals, as well as the cellular functions of TORC2, are far less well understood. Additional open questions in the field concern the relationships between TORC1 and TORC2, as well as the links with other nutrient-responsive pathways. Here I review the main features of TORC1 and TORC2, with a particular focus on yeasts as model organisms.