Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P42345 (mTOR)
 26,049 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Until 2006, immunotherapy (interferon-alpha or interleukin 2) was the standard medical treatment for metastatic renal cell carcinoma (RCC), and its results were disappointing: despite a few cases of complete response with prolonged survival, median survival was one year. Better understanding of the molecular mechanisms of tumor angiogenesis, especially in clear cell carcinoma, has led to the development of multiple targeted therapies to inhibit key effectors: vascular endothelial growth factor (VEGF), VEGF receptor, and mTOR (target of rapamycin). Two inhibitors targeting several protein kinases, including the VEGF receptor, have increased progression-free survival in patients with metastatic RCC and are now commercially available: sunitinib (Sutent) as first-line treatment and sorafenib (Nexavar) as second-line treatment. These targeted therapies will certainly affect overall survival, but it is too early for any firm conclusions. Their side-effects, usually low or moderate, include asthenia, anorexia, diarrhea, hand-and-foot syndrome and hypertension. Optimal management is required to ensure prolonged exposure. Other drugs have been effective: bevacizumab (Avastin), a monoclonal antibody inhibiting VEGF, increases progression-free survival as second-line treatment, and temsirolimus (Torisel), an mTOR protein kinase inhibitor, increases overall survival in the population of patients with poor prognosis. These targeted drugs will serve as the basis for development of future therapeutic strategies.
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PMID:[Renal cell carcinoma and antiangiogenic therapies]. 1803 17

Cardiovascular disease is the major cause of death in renal transplant recipients. Renal transplant recipients share the same cardiovascular risk factors as the general population, including hypertension, hyperlipidemia, diabetes mellitus, smoking, and positive family history. However, renal transplant recipients are also exposed to transplant-specific risk factors such as chronic immunosuppression. Most renal transplant recipients receive combinations or permutations of immunosuppressive drugs including a calcineurin inhibitor (cyclosporine or tacrolimus), a mammalian target of rapamycin (mTOR) inhibitor (sirolimus), an antiproliferative drug (mycophenolate mofetil and azathioprine), and corticosteroids. Cyclosporine and tacrolimus can induce glucose intolerance, hypertension, and hyperlipidemia. Sirolimus can induce hyperlipidemia. Corticosteroids can induce glucose intolerance, hypertension, hyperlipidemia, and weight gain. Central to the development of metabolic complications in renal transplant recipients is insulin resistance induced by immunosuppressive drugs. Insulin resistance is considered to be the central pathophysiological feature of metabolic syndrome, which is linked to increased risk of cardiovascular disease and to chronic renal failure. Therefore, metabolic syndrome likely contributes to cardiovascular disease and chronic renal allograft dysfunction in renal transplant recipients. Treatment of metabolic complications in renal transplant recipients is difficult, as conversion to an alternate immunosuppressive drug may lead to introduction of new metabolic complications, and as discontinuation of immunosuppressive therapy may lead to rejection. Future research should focus on designing immunosuppressive regimens that have minimal effects on insulin resistance and metabolic complications but that are effective in preventing acute rejection and in prolonging both allograft and patient survival.
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PMID:Immunosuppression and metabolic syndrome in renal transplant recipients. 1837 Jun 95

This study examined whether endogenous extracellular adenosine acts to facilitate the adaptive response of the heart to chronic systolic overload. To examine whether endogenous extracellular adenosine can protect the heart against pressure-overload-induced heart failure, transverse aortic constriction was performed on mice deficient in extracellular adenosine production as the result of genetic deletion of CD73. Although there was no difference in left ventricular size or function between CD73-deficient mice (knockout [KO] mice) and wild-type mice under unstressed conditions, aortic constriction for 2 or 4 weeks induced significantly more myocardial hypertrophy, left ventricular dilation, and left ventricular dysfunction in KO mice compared with wild-type mice. Thus, after 2 weeks of transverse aortic constriction, left ventricular fractional shortening decreased to 27.4+/-2.5% and 21.9+/-1.7% in wild-type and KO mice, respectively (P<0.05). Consistent with a role of adenosine in reducing tissue remodeling, KO mice displayed increased myocardial fibrosis and myocyte hypertrophy compared with wild-type mice. Furthermore, adenosine treatment reduced phenylephrine-induced cardiac myocyte hypertrophy and collagen production in cultured neonatal rat cardiac myocytes and cardiac fibroblasts, respectively. Consistent with a role for adenosine in modulating cardiomyocyte hypertrophy, KO mice demonstrated increased activation of mammalian target of rapamycin signaling, accompanied by higher expression of the hypertrophy marker atrial natriuretic peptide. Conversely, the adenosine analogue 2-chloro-adenosine significantly reduced cell size, mammalian target of rapamycin/p70 ribosomal S6 kinase activation, and atrial natriuretic peptide expression in cultured neonatal cardiomyocytes. These data demonstrate that CD73 helps to preserve cardiac function during chronic systolic overload by preventing maladaptive tissue remodeling.
Hypertension 2008 Jun
PMID:Ecto-5'-nucleotidase deficiency exacerbates pressure-overload-induced left ventricular hypertrophy and dysfunction. 1839 Oct 89

The nephrotic range of proteinuria is uncommon in scleroderma renal crisis. This 46-yr-old woman with a medical history of scleroderma presented with very high blood pressure, a sudden elevation of serum creatinine, and proteinuria in the nephrotic range. Renal biopsy revealed onion-skin type of arterial changes with necrosis, confirming the presence of scleroderma nephropathy. Electron microscopy showed diffuse fusion of foot processes. Immunohistochemical staining (IHC) revealed increased expression in glomeruli of phosphorylated mammalian target of rapamycin (p-mTOR). These findings suggest that fusion of foot processes and activation of mammalian target of rapamycin-dependent pathways in podocytes are most likely responsible for the severe proteinuria in this patient with scleroderma nephropathy.
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PMID:Nephrotic range proteinuria: rare manifestation of scleroderma renal crisis. 1846 63

The targeted therapies sunitinib, sorafenib, temsirolimus, and bevacizumab (when used in combination with interferon-alpha2a) have dramatically improved outcomes for patients with advanced renal cell carcinoma (RCC). Clinical application of these novel agents outside the trial setting, however, may present some challenges for treating individual patients with unique needs. In some patients, dose modifications may be considered for potential drug interactions and for management of severe cases of hematologic or nonhematologic toxicities. The more common grade 3 or 4 side effects with sunitinib and sorafenib include hypertension, fatigue, hand-foot syndrome, elevated lipase, lymphopenia, and neutropenia. Congestive heart failure is a less common but serious side effect that warrants treatment discontinuation. Temsirolimus exhibits a different side-effect profile, with the more common grade 3 or 4 side effects being metabolic in nature (i.e., elevated triglycerides, elevated glucose, hypophosphatemia) as a result of its inhibitory effects on the mammalian target of rapamycin-regulated lipid and glucose pathways. Asthenia, rash, and dyspnea also occur in patients receiving temsirolimus. Virtually all of the side effects associated with these agents can be managed effectively in the majority of patients with medical treatment or supportive interventions. Recognition and prompt management of side effects are important to avoid unnecessary dose reductions that may result in suboptimal efficacy.
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PMID:Targeted therapies for metastatic renal cell carcinoma: an overview of toxicity and dosing strategies. 1883 39

Chronic kidney disease is often complicated by uremic cardiomyopathy that consists of left ventricular hypertrophy and interstitial fibrosis. It is thought that hypertension and volume overload are major causes of this disease, but here we sought to identify additional mechanisms using a mouse model of chronic renal insufficiency. Mice with a remnant kidney developed an elevated blood urea nitrogen by 1 week, as expected, and showed progressive cardiac hypertrophy and fibrosis at 4 and 8 weeks even though their blood pressures were not elevated nor did they show signs of volume overload. Cardiac extracellular signal-regulated kinase (ERK) was activated in the uremic animals at 8 weeks. There was also an increased phosphorylation of S6 kinase, which is often mediated by activation of the mammalian target of rapamycin (mTOR). To test the involvement of this pathway, we treated these uremic mice with rapamycin and found that it reduced cardiac hypertrophy. Reduction of blood pressure, however, by hydralazine had no effect. These studies suggest that uremic cardiomyopathy is mediated by activation of a pathway that involves the mTOR pathway.
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PMID:Uremic cardiac hypertrophy is reversed by rapamycin but not by lowering of blood pressure. 1933 17

The clinical efficacy of exercise training in individuals with heart failure is well established, but the mechanism underlying such efficacy has remained unclear. An imbalance between cardiac hypertrophy and angiogenesis is implicated in the transition to heart failure. We investigated the effects of exercise training on cardiac pathophysiology in hypertensive rats. Dahl salt-sensitive rats fed a high-salt diet from 6 weeks of age were assigned to sedentary or exercise (swimming)-trained groups at 9 weeks. Exercise training attenuated the development of heart failure and increased survival, without affecting blood pressure, at 18 weeks. It also attenuated left ventricular concentricity without a reduction in left ventricular mass or impairment of cardiac function. Interstitial fibrosis was increased and myocardial capillary density was decreased in the heart of sedentary rats, and these effects were attenuated by exercise. Exercise potentiated increases in the phosphorylation of Akt and mammalian target of rapamycin observed in the heart of sedentary rats, whereas it inhibited the downregulation of proangiogenic gene expression apparent in these animals. The abundance of the p110alpha isoform of phosphatidylinositol 3-kinase was decreased, whereas those of the p110gamma isoform of phosphatidylinositol 3-kinase and the phosphorylation of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase were increased, in the heart of sedentary rats, and all of these effects were prevented by exercise. Thus, exercise training had a beneficial effect on cardiac remodeling and attenuated heart failure in hypertensive rats, with these effects likely being attributable to the attenuation of left ventricular concentricity and restoration of coronary angiogenesis through activation of phosphatidylinositol 3-kinase(p110alpha)-Akt-mammalian target of rapamycin signaling.
Hypertension 2009 Apr
PMID:Exercise training alters left ventricular geometry and attenuates heart failure in dahl salt-sensitive hypertensive rats. 1956 40

To explain ventricular concentric and/or eccentric hypertrophy in chronic kidney disease, past studies suggested that this was the result of increased preload and/or afterload. Using a renal ablation model of the mouse with documented absence of hypertension, Siedlecki et al. provide evidence for the involvement of the mammalian target of rapamycin (mTOR) pathway. This suggests that load-independent primary stimuli trigger or contribute to ventricular hypertrophy and fibrosis in uremia.
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PMID:Left ventricular hypertrophy in renal disease: beyond preload and afterload. 1916 75

The purpose of this study was to compare the effects of sirolimus (SRL) vs cyclosporine (CsA) concerning the cardiovascular mechanisms hypothetically contributing to hypertension development. Three rat groups were studied: control (vehicle), CsA (5 mg/kg/d), and SRL (1 mg/kg/d). The following parameters were evaluated after 7 weeks of treatment: blood pressured (BP) and heart rate (HR; tail cuff), lipid profile, hematology, plasma and platelet 5-HT and catecholamines (HPLC-ECD), and oxidative equilibrium (serum malondialdehyde [MDA] and total antioxidant status [TAS]). Systolic (SBP) and diastolic blood pressure (DBP) values were higher (P < .001) in both the CsA (146.2 +/- 4.5 and 124.9 +/- 4.5 mm Hg) and SRL (148.9 +/- 4.8 and 126.4 +/- 6.0 mm Hg) groups vs the controls (115.9 +/- 3.3 and 99.1 +/- 2.0 mm Hg). However, HR values were elevated in CsA but not SRL animals. The dyslipidemic pattern of CsA was even more enhanced in the SRL group, with significantly higher low-density lipoprotein cholesterol (LDL-c) and triglyceride (TG) levels vs CsA (P < .05); red blood cells, hematocrit, hemoglobin concentration, mean platelet volume, and platelet distribution width were significantly (P < .05) higher in the SRL vs CsA group. The pro-oxidative profile (increased MDA/TAS) in the CsA group was not reproduced in the SRL cohort. While plasma and platelet 5-HT were elevated in SRL rats, catecholamine content was higher in CsA animals. In conclusion, this study demonstrated that CsA and SRL produce identical hypertensive effects. However, while CsA promotes oxidative stress and sympathetic activation, SRL mainly interferes with lipid profile and hematological parameters. Thus, the hypertensive effects of CsA, a calcineurin inhibitor, and of SRL, an mTOR inhibitor, are associated with impairment of distinct cardiovascular pathways.
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PMID:Hypertension induced by immunosuppressive drugs: a comparative analysis between sirolimus and cyclosporine. 1937 75

Sirolimus (SRL) is a non-nephrotoxic immunosuppressive drug blocking T-cell proliferation through mTOR inhibition. SRL can be used as (1) an early drug in a calcineurin inhibitor-free protocol in the first 3 months after transplantation, (2) in the early and late conversion protocols as suggested by the multicenter randomized CONVERT trial, and (3) in recipients from marginal donors, because calcineurin inhibitors can increase the preexisting renal damage induced by age, hypertension, and diabetes that are frequent in elderly cadaveric donors. In any case, SRL should be used in patients with a cutoff of proteinuria (<or=800 mg/24 hr) or proteinuria-to-creatinine ratio less than 0.11.
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PMID:Review of symposium. Sirolimus in kidney transplantation. 1938 85


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