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

Renal cell carcinoma (RCC) affects 38,000 individuals in the U.S. yearly. Seventy-five percent of cases are clear-cell carcinomas, and a majority is driven by dysfunction of the von Hippel-Lindau (VHL) gene. VHL loss of function and other non-VHL pathways leading to RCC share aberrant activation of the hypoxic response, such as upregulation of vascular endothelial growth factor (VEGF) and consequent neoangiogenesis. Metastatic RCC has been notoriously resistant to therapy. For decades, its treatment has been based on nephrectomy and limited use of toxic and often inefficient immunotherapy with interleukin-2 or interferon-alpha. However, new biologic agents are beginning to break the resistance barrier. Small-molecule multikinase inhibitors that target VEGF receptors (sunitinib and sorafenib) have a favorable toxicity profile and can prolong time to progression and preserve quality of life when used in newly diagnosed or previously treated patients. The anti-VEGF antibody bevacizumab enhances the response rate and prolongs disease control when added to interferon-alpha. Temsirolimus, a mammalian target of rapamycin inhibitor, prolongs the survival duration of patients with poor-risk disease. Despite three new drugs being approved for RCC in the past 2 years, responses are mostly partial and of limited duration. Multiple new drugs and drug combinations are undergoing clinical trials and will likely impact the treatment of RCC in future years. Compounds found to be active in the metastatic setting are now being tried in earlier stage disease in an attempt to improve curability. However, no method has yet been validated to predict patient response to these newer treatments.
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PMID:Renal cell carcinoma: new developments in molecular biology and potential for targeted therapies. 1816 17

Expression of the transcription factor hypoxia-inducible factor 1 (HIF-1), which plays a key role in cellular adaptation to hypoxia, was investigated in normal colorectal mucosa (ten), adenomas (61), and carcinomas (23). Tissue samples were analyzed for HIF-1 alpha, its upstream regulators, von Hippel-Lindau factor, AKT, and mammalian target of rapamycin (mTOR) and its downstream targets glucose transporter 1 (GLUT1), carbonic anhydrase IX, stromal-cell-derived factor 1 (SDF-1) by immunohistochemistry. In normal colorectal mucosa, HIF-1 alpha was observed in almost all nuclei of surface epithelial cells, probably secondary to a gradient of oxygenation, as indicated by pimonidazole staining. The same staining pattern was present in 87% of adenomas. In carcinomas, HIF-1 alpha was present predominantly around areas of necrosis (78%). Active AKT and mTOR, were present in all adenomas, carcinomas, and in normal colorectal mucosa. GLUT1 and SDF-1 were present in the normal surface epithelium of all adenoma cases, whereas in the carcinoma GLUT1 was located around necrotic regions and SDF-1 was present in all epithelial cells. In conclusion, HIF-1 alpha appears to be physiologically expressed in the upper part of the colorectal mucosa. The present observations support that upregulation of HIF-1 alpha and its downstream targets GLUT1 and SDF-1 in colorectal adenomas and carcinomas may be due to hypoxia, in close interaction with an active phosphatidylinositol 3-kinases-AKT-mTOR pathway.
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PMID:Presence of HIF-1 and related genes in normal mucosa, adenomas and carcinomas of the colorectum. 1835 86

Renal-cell carcinoma represents 95% of all renal tumours. The Von Hippel-Lindau (VHL) tumor-suppressor gene is mutated or silenced in most clear cell renal carcinomas. pVHL loss results in the stabilization of the heterodimeric transcription factor hypoxia-inducible factor (HIF) and enhanced transactivation of HIF target genes. HIF itself has been difficult to inhibit with drug-like molecules although a number of agents that indirectly inhibit HIF, including mTOR (mammalian target of rapamycin) inhibitors, have been identified. Moreover, a number of drugs have been developed that target HIF-responsive gene products, such as vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF), implicated in tumor angiogenesis. Many of these targeted therapies, especially sunitinib, have demonstrated significant activity in kidney cancer clinical trials and represent a substantive advance in the treatment of this disease.
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PMID:[Current strategies in the treatment of renal-cell cancer: targeted therapies]. 1838 Oct 31

The signalling components upstream and downstream of the protein kinase mammalian target of rapamycin (mTOR) are frequently altered in a wide variety of human diseases. Upstream of mTOR key signalling molecules are the small GTPase Ras, the lipid kinase PI3K, the Akt kinase, and the GTPase Rheb, which are known to be deregulated in many human cancers. Mutations in the mTOR pathway component genes TSC1, TSC2, LKB1, PTEN, VHL, NF1 and PKD1 trigger the development of the syndromes tuberous sclerosis, Peutz-Jeghers syndrome, Cowden syndrome, Bannayan-Riley-Ruvalcaba syndrome, Lhermitte-Duclos disease, Proteus syndrome, von Hippel-Lindau disease, Neurofibromatosis type 1, and Polycystic kidney disease, respectively. In addition, the tuberous sclerosis proteins have been implicated in the development of several sporadic tumors and in the control of the cyclin-dependent kinase inhibitor p27, known to be of relevance for several cancers. Recently, it has been recognized that mTOR is regulated by TNF-alpha and Wnt, both of which have been shown to play critical roles in the development of many human neoplasias. In addition to all these human diseases, the role of mTOR in Alzheimer's disease, cardiac hypertrophy, obesity and type 2 diabetes is discussed.
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PMID:The mTOR pathway and its role in human genetic diseases. 1859 80

The mammalian target of rapamycin (mTOR) is part of two distinct complexes, mTORC1, containing raptor and mLST8, and mTORC2, containing rictor, mLST8 and sin1. Although great endeavors have already been made to elucidate the function and regulation of mTOR, the cytoplasmic nuclear distribution of the mTOR complexes is unknown. Upon establishment of the proper experimental conditions, we found mTOR, mLST8, rictor and sin1 to be less abundant in the nucleus than in the cytoplasm of non-transformed, non-immortalized, diploid human primary fibroblasts. Although raptor is also high abundant in the nucleus, the mTOR/raptor complex is predominantly cytoplasmic, whereas the mTOR/rictor complex is abundant in both compartments. Rapamycin negatively regulates the formation of both mTOR complexes, but the molecular mechanism of its effects on mTORC2 remained elusive. We describe that in primary cells short-term treatment with rapamycin triggers dephosphorylation of rictor and sin1 exclusively in the cytoplasm, but does not affect mTORC2 assembly. Prolonged drug treatment leads to complete dephosphorylation and cytoplasmic translocation of nuclear rictor and sin1 accompanied by inhibition of mTORC2 assembly. The distinct cytoplasmic and nuclear upstream and downstream effectors of mTOR are involved in many cancers and human genetic diseases, such as tuberous sclerosis, Peutz-Jeghers syndrome, von Hippel-Lindau disease, neurofibromatosis type 1, polycystic kidney disease, Alzheimer's disease, cardiac hypertrophy, obesity and diabetes. Accordingly, analogs of rapamycin are currently tested in many different clinical trials. Our data allow new insights into the molecular consequences of mTOR dysregulation under pathophysiological conditions and should help to optimize rapamycin treatment of human diseases.
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PMID:Cytoplasmic and nuclear distribution of the protein complexes mTORC1 and mTORC2: rapamycin triggers dephosphorylation and delocalization of the mTORC2 components rictor and sin1. 1861 46

Angiogenesis is an important factor for cancer development and progression in humans. Hereditary and sporadic renal cell carcinoma are characterized by inactivation of the Von-Hippel Lindau (VHL) gene, which results in hyperactivity of the hypoxia-inducible factor-a (HIFa). As a consequence, there is a production of angiogenic factors, such as vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF). The activity of these factors is associated with oncogenesis, growth, and metastatic potential of renal-cell carcinoma. These data indicate that angiogenic factors are the promising therapeutic targets in this disease. Surgery can cure the patients with renal cancer if disease is diagnosed at an early stage. On the contrary, inoperable or metastatic disease is not curable. Until recently, the only drugs approved for the treatment of advanced disease were the cytokines, interferon, and interleukin. Nevertheless, only a minority of patients (about 15%) would benefited from this treatment, while the toxicity was considerable. During the last 5 years a new era of biological agents, with considerable activity has been developed and tested in clinical trials and (some of them) have been approved in USA and Europe. These agents are: Sunitinib, Bevacizumab, Sorafenib and Temserolimus. Bevacizumab is an anti-VEGF monoclonal antibody, Sunitinib and Sorafenib are multi- tyrosine kinase inhibitors (TKIs), while Temserolimus is a mTOR inhibitor. The common these in their development is the inhibition of angiogenesis, which may explain their significant activity in renal-cell carcinoma. All the agents have been proven more effective than the interferon as first or second-line treatment. This review will focus in these recent developments and the intense continuing clinical research in this field.
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PMID:Targeting angiogenesis in renal cell carcinoma. 1869 Aug 41

Renal cell carcinoma has made considerable progress in the past years, and new emerging strategies are coming almost every year since 2005. Development of targeted therapies in renal cell cancer is largely due to the fact that Von Hippel Lindau gene is often mutated in sporadic renal cell cancer. Von Hippel Lindau protein abnormalities lead to accumulation of hypoxia inducible factor-alpha, and activation of a series of gene, including vascular endothelial growth factor, and thus induce angiogenesis. Results from many recent studies with new agents, blocking the vascular endothelial growth factor pathway or the mammalian target of rapamycin pathway, have been recently reported and offer new strategic options for the patients with metastatic renal cell carcinoma. Sunitinib, sorafenib, and combination of bevacizumab and interferon improves progression free survival in either first or second line treatment of renal cell cancer and have been approved. Temsirolimus, a mammalian target of rapamycin inhibitor regulating hypoxia inducible factor-alpha, improves survival in renal cancer with poor risk features. Finally, everolimus improves progression free survival in patients who fail tyrosine kinase inhibitors. Overall, treatment of metastatic renal cell carcinoma is currently moving from the cytokine era to the targeted agent era. However, many questions still remain on the efficacy of combination treatments and on the best way to get complete remission, which is probably the best way to lead to cure of metastatic renal cell cancer in the future.
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PMID:Signaling inhibitors in metastatic renal cell carcinoma. 1883 38

von Hippel-Lindau (VHL) disease is a genetic syndrome based on an abnormality of the VHL gene located on the short arm of chromosome 3. Clinically, it presents as multiple tumors at several levels. The VHL gene product (pVHL) acts as a tumor-suppressing protein. In conditions of hypoxia it leads to an increase in several growth factor levels. mTOR inhibitors have proved to have dual properties: immunosuppressive and antitumor effects. Herein we have presented a case in which conversion to sirolimus improved graft function and also caused regression of retinal angioblastomas.
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PMID:Conversion to rapamycin in a renal transplant patient with von Hippel-Lindau disease: encouraging results-a case report. 1901 Feb 10

von Hippel-Lindau (VHL) tumor suppressor loss results in hypoxia-inducible factor alpha (HIF-alpha) stabilization and occurs in 70% of sporadic clear cell renal carcinomas (ccRCCs). To determine whether opposing influences of HIF-1alpha and HIF-2alpha on c-Myc activity regulate human ccRCC progression, we analyzed VHL genotype and HIF-alpha expression in 160 primary tumors, which segregated into three groups with distinct molecular characteristics. Interestingly, ccRCCs with intact VHL, as well as pVHL-deficient HIF-1alpha/HIF-2alpha-expressing ccRCCs, exhibited enhanced Akt/mTOR and ERK/MAPK signaling. In contrast, pVHL-deficient ccRCCs expressing only HIF-2alpha displayed elevated c-Myc activity, resulting in enhanced proliferation and resistance to replication stress. These reproducible distinctions in ccRCC behavior delineate HIF-alpha effects on c-Myc in vivo and suggest molecular criteria for selecting targeted therapies.
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PMID:HIF-alpha effects on c-Myc distinguish two subtypes of sporadic VHL-deficient clear cell renal carcinoma. 1906 30

Drugs that target the vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) pathways have revolutionized the treatment of patients with metastatic renal cell cancer (RCC). Patients with clear cell RCC often have mutations or silencing of the von Hippel Lindau gene leading to an accumulation of HIF 1 alpha. This allows growth factors such as VEGF and PDGF to be upregulated to promote angiogenesis and endothelial stabilization. Both sunitinib and sorafenib target VEGF and PDGF receptor tyrosine kinases while bevacizumab is a monoclonal antibody to VEGF. These three agents have demonstrated superior progression free survival in patients with metastatic RCC when compared to interferon or placebo. Newer anti-VEGF agents such as axitinib, pazopanib and cediranib are currently under investigation to elucidate future treatment options. The mammalian target of rapamycin (mTOR) is downstream of the VEGF pathway and has been targeted with drugs including temsirolimus and everolimus. This review will detail the pharmacologic and molecular activity of these agents and how they translate into clinical efficacy.
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PMID:Anti-angiogenic targets in the treatment of advanced renal cell carcinoma. 1907 90


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