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)

Malignant renal tumors constitute 3% of human cancers, although their frequency differs greatly in various areas. Since the fifties, the incidence of renal cancers has been increasing, but at the some time the prognosis has been improving. In particular, in the last years, several new treatment modalities have been introduced, relying on the understanding of renal cancer biology. The identified etiological factors include smoking, increased body mass, dietary factors and chronic renal disease. There are several renal tumor types differing in morphology, molecular genetics and biology. Inactivation of the VHL gene leads to formation of the most frequent form in adults, namely clear cell carcinoma. The VHL gene product, a component of an ubiquitin-ligase complex, regulates expression of several genes. Papillary carcinomas depend mainly on the HGF receptor gene (c-Met) activating mutations. At least two types of papillary carcinomas exist, which have different morphology and prognosis. The molecular biology of chromophobe carcinoma and oncocytoma is poorly understood. Differential diagnosis of these tumors is particularly difficult and may require extensive immunohistochemical and molecular studies. Collecting duct carcinoma and medullary carcinoma are extremely aggressive but rare tumors. Some renal tumors have been described or recognized only relatively recently; these newer entities include multilocular cystic clear cell carcinoma, spindle cell papillary mucinous carcinoma, tubulocystic carcinoma, renal epithelial and stromal tumor, epithelioid and oncocytic angiomyolipoma. Besides histological typing, the prognostic factors include tumor stage, grade and several immunohistochemical and molecular markers that are currently under elaboration. The improved prognosis in renal cancer depends on earlier detection, but also on refinement of therapeutic methods. Small tumors may currently be treated by partial nephrectomy or radiofrequency ablation and larger ones by a laparoscopic approach. All these methods seem to give satisfactory results with low morbidity and mortality rates. Renal carcinoma is notorious for its low sensitivity to chemotherapy and radiotherapy. For several years, immunological treatment with IL-2 and INF-alpha was the only adjuvant therapy method. However, recently several new drugs have been introduced; they act on tyrosine-kinase receptors, VEGF, c-Met or mTOR pathway. With this progress, perfect understanding of renal tumor biology and exact histological diagnosis have become of prime practical importance.
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PMID:Pathology of renal tumors in adults. Molecular biology, histopathological diagnosis and prognosis. 1909 56

Gliomas are the most common and deadly form of malignant primary brain tumors. Loss of the tumor-suppressor PTEN and activation of the receptor tyrosine kinases (RTKs) EGF receptor, c-Met, PDGF receptor and VEGF receptor are among the most common molecular dysfunctions associated with glioma malignancy. PTEN interacts with RTK-dependent signaling at multiple levels. These include the ability of PTEN to counteract PI3K activation by RTKs, as well as possible effects of PTEN on RTK activation of the MAPK pathway and RTK-dependent gene-expression regulation. Consequently, PTEN expression affects RTK-induced malignancy. Importantly, the PTEN status was recently found to be critical for the outcome of RTK-targeted clinical therapies that have been developed recently. Combining RTK-targeted therapies with therapies aimed at counteracting the effects of PTEN loss, such as mTOR inhibition, might also have therapeutic advantage. This article reviews the known molecular and functional interactions between PTEN and RTK pathways and their implications for glioma therapy.
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PMID:Interactions between PTEN and receptor tyrosine kinase pathways and their implications for glioma therapy. 1919 61

Recent advances in genomics, proteomics, bioinformatics and systems biology have unraveled the complex aberrant signaling networks in cancer. The knowledge accrued has dramatically increased the opportunities for discovery of novel molecular targets for drug development. Major emphasis is being laid on designing new therapeutic strategies targeting multiple signaling pathways for more effective disease management. However, the translation of in vitro findings to patient management often poses major challenges that limit their clinical efficacy. Here we will discuss how understanding the dysregulated signaling networks can explain the pitfalls in translating the laboratory findings from the bench-to-bedside and suggest novel approaches to overcome these problems using head and neck cancer as a prototype. The five year survival rates of HNSCC patients (about 50% at 5 years) have not improved significantly despite advancements in multimodality therapy including surgery, radiation and chemotherapy. Molecular targeted therapies with inhibitors of EGFR and VEGF either alone, or in combination with conventional treatments have shown limited improved efficacy. The key deregulated signaling pathways in head and neck squamous cell carcinoma (HNSCC) include EGFR, Ras, TGFbeta, NFkappaB, Stat, Wnt/beta-catenin and PI3-K/AKT/mTOR. The aberrant activities of these interrelated signaling pathways contribute to HNSCC development. In depth understanding of the cross-talks between these pathways and networks will form the basis of developing novel strategies for targeting multiple molecular components for more effective prevention and treatment of HNSCC.
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PMID:Overview of current and future biologically based targeted therapies in head and neck squamous cell carcinoma. 1928 26

Targeted therapies are widely used in cancer because of their effectiveness, even in tumours that are resistant to conventional chemotherapy such as kidney or hepatocellular carcinomas. There are different families classified according to their mode of action. The antiangiogenics block tumor angiogenesis by acting on VEGF or its receptor. The main molecules are bevacizumab, sunitinib, and sorafinib. HER inhibitors work by blocking these receptors, which control different signaling intracellular pathways, and include an inhibitor of HER2, trastuzumab, and various inhibitors of HER1, or EGFR, including cetuximab, erlotinib, and gefitinib. Inhibitors of KIT, a membrane receptor, are mainly represented by imatinib, an inhibitor of tyrosine kinase. Finally, mTOR inhibitors act on the signaling pathway PI3K/AKT/mTOR, and key molecules are temsirolimus, everolimus, and deforolimus.
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PMID:[Targeted therapies and their indications in solid neoplasias]. 1929 48

mTOR pathway inhibitors, specifically rapamycin and its derivatives, are promising therapeutics that targets downstream pathways including protein translation. We examined the effects of a series of inhibitors targeting various pathways on ribosomal polysome distribution, overall translation rates, and translation of specific mRNAs in the bone derived prostate cancer cell line, C4-2B. Treatment with either rapamycin, PD98059 or LY294002 failed to change the distribution of polysomes in sucrose gradients. Although no change in the accumulation of heavy polysomes was observed, there was an overall decrease in the rate of translation caused by treatment with rapamycin or LY294002. Inhibiting the MAPK pathway with PD98059 decreased overall translation by 20%, but had no effect on mRNAs containing a 5' terminal oligopyrimidine tract (TOP) sequences or those with complex 5' UTRs. In contrast, treatment with rapamycin for 24 h reduced overall translation by approximately 45% and affected the translation of mRNAs with complex 5' UTRs, specifically VEGF and HIF1alpha. After 24 h, LY294002 treatment alone decreased overall translation by 60%, more than was observed with rapamycin. Although LY294002 and similar inhibitors are effective at blocking prostate cancer cell growth, they act upstream of AKT and PTEN and cancer cells can find a way to bypass this inhibition. Thus, we propose that inhibiting downstream targets such as mTOR or targets of mTOR will provide rational approaches to developing new combination therapies focused on reducing growth of prostate cancer after arrival in the bone environment.
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PMID:Rapamycin selectively reduces the association of transcripts containing complex 5' UTRs with ribosomes in C4-2B prostate cancer cells. 1934 4

The mammalian target of rapamycin (mTOR) is an intracellular protein with a key role in cellular protein synthesis and energy balance that influences many aspects of cell growth and proliferation, including differentiation, cell-cycle progression, angiogenesis, protein degradation and apoptosis. mTOR can be activated by numerous oncogenic signals, such as growth factor activation through the EGF, IGF and VEGF receptors, mutation and silencing of the PTEN tumor suppressor gene, activating mutations in the PI3K catalytic subunit, Akt amplification and the Ras-Raf-MEK pathway. Once activated, the cellular functions of mTOR are achieved through its downstream targets, 4E-BP1 and p70S6K1. The mTOR pathway can be further regulated through a negative feedback loop, which may lead to resistance to specific inhibitors of mTOR. This review will outline the mTOR signaling pathway, which is often activated in cancers and account for tumor proliferation and growth, highlight the rationale in targeting mTOR with a focus on the preclinical and clinical development of one of these inhibitors, deforolimus (AP23573, MK-8669), and discuss potential benefit and barriers to these agents being introduced in the clinic.
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PMID:Targeting the mTOR pathway using deforolimus in cancer therapy. 1937 36

Neuroendocrine tumors (NETs) are considered to be rare but, during the last two decades, their incidence and prevalence has considerably increased in gastro-entero-pancreatic (GEP) NETs. Most GEP-NETs express somatostatin receptors, which could be targets for treatment. The development of somatostatin analogs for treatment of functioning NETs was a revolution in the treatment of these patients and is still a cornerstone for managing hormone-related clinical symptoms. Furthermore, somatostatin analogs have also demonstrated an anti-tumor effect, with stabilization of tumor growth over long periods of time. The development of a long-acting formulation of octreotide long-acting release (LAR) significantly improved the quality of life for patients with functioning NETs in terms of necessitating only monthly injections. The side effects are few and easily manageable. In the future, somatostatin analogs will continue to be a major treatment option for functioning NETs, but will be combined with other biologicals, such as a-interferons, mTOR inhibitors and VEGF inhibitors. A new multireceptor somatostatin analog, SOM230 (pasireotide), as well as chimeric molecules, such as dopastatin (a combination of a somatostatin analogue plus a dopamine agonist), will come into the clinical management of GEP-NETs.
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PMID:Somatostatin analog octreotide LAR in gastro-entero-pancreatic tumors. 1944 73

The recent introduction of drugs that inhibit angiogenesis or the mTOR has provided new options for the treatment of metastatic renal cell carcinoma, a disease which often has a poor prognosis. Chemotherapy and cytokine therapy are largely ineffective. The 5-year survival rate is under 10%. Everolimus, an immunosuppressive drug widely used for the prevention of allograft rejection and an mTOR inhibitor, is one of the latest drugs undergoing clinical trials in metastatic renal cell carcinoma. It has been tested in patients with progressive disease after therapy with tyrosine kinase receptor inhibitors (sunitinib, sorafenib or both), which interfere with signaling pathways, such as the VEGF pathway. Clinical efficacy results (progression-free survival) for everolimus are promising and the safety profile is good.
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PMID:Everolimus (RAD001): an mTOR inhibitor for the treatment of metastatic renal cell carcinoma. 1949 7

VEGF and mTOR inhibitors have encouraging clinical activity for patients with advanced renal cell carcinoma (RCC), but may lead to significant short- and long-term toxicities. Although 40-70% of adverse events (AEs) are grade 1 and 2, 10-20% of patients develop grade 3 or 4 AEs requiring dose reductions, drug holidays or treatment discontinuation. The long-term impact of the most common grade 3 and 4 AEs observed in Phase III trials evaluating VEGF and mTOR inhibitors, including hypertension, decreased left ventricular ejection fraction, hand-foot-syndrome and myelosuppression, are a concern in RCC patients who are living longer and receiving chronic sequential or combination therapy. There is a clear need to develop a more rational way to individualize therapy for RCC. Long-term follow-up from existing Phase II/III trials should provide us with increased understanding of the potential implications of AEs in RCC patients. Prevention, early recognition and aggressive management of side effects are fundamental to avoid significant long-term complications and unnecessary dose reductions, which can ultimately reduce the efficacy of these novel agents.
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PMID:Toxicity associated with the long-term use of targeted therapies in patients with advanced renal cell carcinoma. 1949 16

Primary effusion lymphoma (PEL) is a fatal malignancy, which typically presents as a lymphomatous effusion that later disseminates. Rapamycin (Rapa), which targets mTOR (mammalian target of Rapa), is currently evaluated as a treatment for PEL, but the recent development of PEL in Rapa-treated post-transplant recipients questions the drug's use in PEL. Here, we used a murine model of PEL effusion that mimics the human disease to investigate the anti-PEL activity of Rapa. We found that Rapa reduces ascites accumulation and extends mouse survival. Initially, Rapa reduced PEL load compared with control mice, but most mice rapidly showed PEL progression. Levels of VEGF, which promotes vascular permeability contributing to effusion formation, were significantly reduced in ascites of Rapa-treated mice compared with controls. Expression of IL-10, the principal autocrine growth factor for PEL, was initially reduced in PEL from Rapa-treated mice but rapidly increased despite treatment. We found that the hypoxic environment of ascites and Rapa cooperate in stimulating IL-10 expression in PEL, which likely contributes to the emergence of drug resistance. These results identify Rapa an effective drug to reduce PEL effusions but illustrate the rapid development of drug resistance, which likely limits the efficacy of Rapa in PEL.
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PMID:Targeting the mammalian target of Rapamycin to inhibit VEGF and cytokines for the treatment of primary effusion lymphoma. 1955 30


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