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)

Recent improvements in immunosuppressive therapies have reduced the incidence of acute rejection and increased patient survival. These agents may however contribute to higher rates of mortality due to an increased risk of cardiovascular disease or malignancy. Transplant patients are immunocompromised with a reduced ability to combat the development of malignancy. The higher risk for the activity of oncoviruses may also contribute to the higher incidence and determine specific tumor types. Some immunosuppressants seem to have direct oncogenic effects. In vitro data have demonstrated that calcineurin inhibitors (CNIs) may show direct effects on tumor growth and the development of metastases. In contrast, mTOR inhibitors have demonstrated anti-tumoral properties in vitro and perhaps potent anti-angiogenic effects thereby. Recent studies and registry analyses have confirmed that mTOR inhibitors are associated with a reduced incidence of malignancies. UNOS data demonstrated that an mTOR inhibitor, with or without a CNI, is associated with a reduced incidence of tumors compared to regimens without mTOR inhibitors. The Rapamune Maintenance Regimen study demonstrated that patients receiving sirolimus-based, CNI-free therapy after CsA withdrawal at 3 months showed a reduced incidence of malignancy at 5 years posttransplant, compared with those who continued on a regimen that included CsA. In the CONVERT study, patients converted to sirolimus revealed a significantly lower malignancy rate at 24 months (3.1%) compared with those who continued CNI-based therapy (9.8%, P < .001). The elimination of CNIs and the introduction of sirolimus may, therefore, have a role to reduce the risk of cancer among posttransplant patients.
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PMID:Minimizing the risk of posttransplant malignancy. 1910 Sep 6

The regulation of androgen receptor (AR) expression in prostate cancer is still poorly understood. The activation of the epidermal growth factor receptor (EGFR) in prostate cancer cells was previously shown to lower AR expression by a rapamycin-sensitive, posttranscriptional mechanism involving the AR mRNA 5'-untranslated region (5'-UTR). In a search for an intermediate within the EGFR/phosphoinositide 3-kinase/Akt/mammalian target of rapamycin pathway that regulates AR at this site, we identified the nucleic acid-binding protein, heterogeneous nuclear ribonucleoprotein K (hnRNP-K), by mass spectrometric analysis of Akt immune complexes from lipid raft-enriched subcellular fractions. We show here that hnRNP-K is a novel inhibitor of AR mRNA translation that regulates androgen-responsive gene expression and prostate cancer cell proliferation. A functional hnRNP-K binding site involved in down-regulating AR protein levels was identified in the AR mRNA 5'-UTR. Further analysis revealed that hnRNP-K is also able to inhibit AR translation in the absence of the 5'-UTR, consistent with the presence of additional predicted hnRNP-K binding sites within the AR open reading frame and in the 3'-UTR. Immunohistochemical analysis of a human prostate cancer tissue microarray revealed an inverse correlation between hnRNP-K expression and AR protein levels in organ-confined prostate tumors and a substantial decline in cytoplasmic hnRNP-K in metastases, despite an overall increase in hnRNP-K levels in metastatic tumors. These data suggest that translational inhibition of AR by hnRNP-K may occur in organ-confined tumors but possibly at a reduced level in metastases. HnRNP-K is the first protein identified that directly interacts with and regulates the AR translational apparatus.
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PMID:Heterogeneous nuclear ribonucleoprotein K is a novel regulator of androgen receptor translation. 1925 14

Considerable progress has been made in the treatment of patients with renal cell carcinoma, with innovative surgical and systemic strategies revolutionising the management of this disease. In localised disease, partial nephrectomy for small tumours and radical nephrectomy for large tumours continue to be the gold-standard treatments, with emphasis on approaches that have reduced invasiveness and preserve renal function. Additionally, cytoreductive nephrectomy is often indicated before the start of systemic treatment in patients with metastatic disease as part of integrated management strategy. The effectiveness of immunotherapy, although previously widely used for treatment of metastatic renal cell carcinoma, is still controversial, and is mainly reserved for patients with good prognostic factors. Development of treatments that have specific targets in relevant biological pathways has been the main advance in treatment. Targeted drugs, including inhibitors of the vascular endothelial growth factor and mammalian target of rapamycin pathways, have shown robust effectiveness and offer new therapeutic options for the patients with metastatic disease.
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PMID:Renal cell carcinoma. 1926 25

Neuroblastoma (NB) is one of the most common pediatric solid tumors originating from the neural crest lineage. Despite intensive treatment protocols including megatherapy with hematopoietic stem cell transplantation, the prognosis of NB patients remains poor. More effective therapeutics are required. High vascularity has been described as a feature of aggressive, widely disseminated NB. Our previous work demonstrated the overexpression of vascular endothelial growth factor (VEGF) in NB, and we showed that an anti-VEGF receptor (VEGFR-2) antibody could induce sustained NB tumor suppression and regression. Sunitinib is a kinase inhibitor targeting platelet-derived growth factor receptors and VEGFRs and, therefore, a promising antiangiogenic agent. In this study, we investigated the antitumor activity of sunitinib and its synergistic cytotoxicity with conventional (cyclophosphamide) and novel (rapamycin) therapies. Both NB cell lines and tumor-initiating cells from patient tumor samples were used in our in vitro and in vivo models for these drug testing. We show that sunitinib inhibits tumor cell proliferation and phosphorylation of VEGFRs. It also inhibits tumor growth, angiogenesis, and metastasis in tumor xenograft models. Low-dose sunitinib (20 mg/kg) demonstrates synergistic cytotoxicity with an mTOR inhibitor, rapamycin, which is more effective than the traditional chemotherapeutic drug, cyclophosphamide. These preclinical studies provide the evidence of antitumor activity of sunitinib both in the early stage of tumor formation and in the progressive metastatic disease. These studies also provide the framework for clinical trial of sunitinib, alone and in combination with conventional and novel therapies to increase efficacy and improve patient outcome in NB.
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PMID:In vivo antitumor and antimetastatic activity of sunitinib in preclinical neuroblastoma mouse model. 1941 27

Phaeochromocytoma and paraganglioma are rare neuroendocrine tumours (NETS). They may be benign or malignant but the pathological distinction is mainly made when metastases are present. Available treatments in the form of surgery, chemotherapy, and radionuclide therapy may improve symptoms and biochemical markers, but the results for the control of tumour bulk are less favourable. Furthermore, responses to treatment are frequently short-lived. This short review outlines the main molecular and histological features of malignant phaeochromocytoma and the difficulties in differentiating between benign and malignant disease. We list current therapies used for malignant pheochromocytoma; however, these generally achieve relatively low success rates. Hence, there is a need for new and more effective therapies. In vitro studies have implicated the PI3/Akt/mTOR pathway in the pathogenesis of malignant NETS, including phaeochromocytoma. Everolimus (RAD001, Novartis UK) is a compound that inhibits mTOR (mammalian Target Of Rapamycin) signalling. We have used RAD001 in four patients with progressive malignant paraganglioma/phaeochromocytoma in addition to other therapies (with institutional approval for compassionate use), and evaluated the effects of this treatment. We outline these four cases and review the theoretical background for this therapy, although the outcomes were relatively disappointing.
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PMID:Novel and evolving therapies in the treatment of malignant phaeochromocytoma: experience with the mTOR inhibitor everolimus (RAD001). 1942 40

Several selected targeted agents are being investigated in combination with endocrine therapy for patients with breast cancer in an attempt to overcome or prevent endocrine resistance. The role of type I growth factor receptors epidermal growth factor receptor (EGFR) and HER2 in cross-talk with estrogen receptor (ER) signaling has been confirmed in preclinical studies in which various inhibitors have yielded additive or synergistic effects when combined with endocrine agents. Recently, several results from clinical trials investigating this concept have been reported. In ER-positive/HER-positive advanced breast cancer, the addition of trastuzumab to the aromatase inhibitor anastrozole, or the tyrosine kinase inhibitor (TKI) lapatinib to letrozole, both have significantly improved progression-free survival (PFS). The EGFR TKI gefitinib combined with tamoxifen as first-line therapy for ER-positive metastatic disease improved PFS (but not objective response rate) for patients with no previous endocrine therapy or completion of previous adjuvant therapy. A second study in a similar setting showed significant improvement in PFS for gefitinib plus anastrozole. Although it is encouraging that this approach could delay resistance, only a small proportion of patients benefit. Attempts to identify likely responders have been made in the neoadjuvant setting, with pre- and post-treatment biopsies being used to study biomarker changes. A recent preoperative study of letrozole with or without the mammalian target of rapamycin (mTOR) inhibitor everolimus reported greater tumor shrinkage for the combination, with changes in proliferation being predictive for response together with strong expression of protein S6 kinase, a downstream marker of activated mTOR. Key aspects that need to be addressed in future trials include understanding the mechanisms of action for each novel agent, designing the best trial and endpoints to demonstrate added benefit, and ensuring appropriately stratified populations based on previous endocrine exposure and/or sensitivity.
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PMID:Enhancing the efficacy of hormonal agents with selected targeted agents. 1956 Oct 4

Renal cell carcinoma (RCC) is very resistant to both chemotherapy and radiotherapy. Localized disease can be cured by surgery but most patients are diagnosed when distant metastases are already present and about 30% of patients relapse after nephrectomy. Until 2 years ago, cytokine-based immunotherapy (interleukin-2 and interferon-alpha) was the only therapeutic option for advanced RCC patients. Fewer than 20% of patients benefit from this treatment, but some of these may experience very prolonged complete responses and progression-free intervals, suggesting a possibility of cure in a very few cases. Thanks to our expanding knowledge of the biology and pathogenesis of RCC, the treatment of this disease has recently undergone a major advance, through the development of potent angiogenesis inhibitors and targeted agents. Bevacizumab, an antibody directed against vascular endothelial growth factor (VEGF), has shown significant activity in combination with interferon-alpha (IFN-alpha). Sunitinib and sorafenib, multikinase inhibitors with proven antiangiogenic activity, have also been approved for the treatment of this tumor. Finally, temsirolimus and everolimus, which belong to the family of mammalian target of rapamycin (mTOR), have shown some activity in selected patients. The aim of this paper is to review clinical trials with these new agents, describing their activity and profiles of toxicity, and to evaluate potential future developmental strategies.
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PMID:A survey of therapy for advanced renal cell carcinoma. 1957

Soft-tissue sarcomas (STSs) are a heterogeneous group of rare malignant tumors predominantly arising from the embryonic mesoderm. The mainstay of curative therapy is the complete surgical resection of all tumor manifestations with negative histological margins. However, up to 50% of patients will develop distant metastases during the course of their disease. The prognosis for those patients is grim with a 5-year overall survival of less than 10%. First-line systemic therapy with ifosfamide and doxorubicin results in overall response rates of only 20% by conventional response evaluation criteria in solid tumors (RECIST). However, stabilization of disease can be seen in a greater proportion. Therefore, the role of the RECIST criteria has been questioned and the implementation of new imaging studies (e.g., FDG-PET) has shown promising results in assessing early tumor response to therapy. Furthermore, a broader insight into the molecular pathways of sarcomagenesis has been gained in recent years, revealing intriguing targets for new therapeutic approaches (e.g., VEGF, VEGF receptor, IGF receptor, EGF receptor, mTOR and cyclin-dependent kinases). In addition, a growing body of evidence is linking specific genetic aberrations with clinical outcome (e.g., SYT-SXX translocation in synovial sarcoma). With further insight into the biology of STS and the combination of new treatment options with modern imaging techniques, we will most certainly be able to improve clinical outcome in patients with STS in the upcoming years.
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PMID:New medical treatment options and strategies to assess clinical outcome in soft-tissue sarcoma. 1967 Oct 35

Melanoma is one of the fastest growing tumor types in the United States. Immunotherapy and chemotherapy benefit only a few patients with metastatic disease. Therapy targeting a signaling pathway critical to the cancer's growth can provide dramatic benefit in several other malignancies and may be a valuable strategy for advanced melanoma, if drugs with a favorable therapeutic index are effective against essential molecular pathways. One such target is the V600E "gain-of-function" BRAF mutation found in 60% of melanomas; other mutations or molecular alterations cooperate with V600E BRAF, particularly those that cause loss of function of PTEN, upstream of Akt and mammalian target of rapamycin. Rapid development of new agents, a better understanding of the target pathways and mechanisms of resistance, and carefully designed strategies to optimize combinations and sequences of these agents, potentially with chemotherapy or immunotherapy, may ultimately have the potential to overcome the previously insurmountable obstacle of therapy resistance in melanoma.
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PMID:Inside life of melanoma cell signaling, molecular insights, and therapeutic targets. 1967 16

Patients with a solid organ transplant have increased in numbers and in individual survival in Switzerland over the last decades. As a consequence of long-term immunosuppression, skin cancer in solid organ recipients (SOTRs) has been recognized as an important problem. Screening and education of potential SOTRs about prevention of sun damage and early recognition of skin cancer are important before transplantation. Once transplanted, SOTRs should be seen by a dermatologist yearly for repeat education as well as early diagnosis, prevention and treatment of skin cancer. Squamous cell carcinoma of the skin (SCC) is the most frequent cancer in the setting of long-term immunosuppression. Sun protection by behaviour, clothing and daily sun screen application is the most effective prevention. Cumulative sun damage results in field cancerisation with numerous in-situ SCC such as actinic keratosis and Bowen's disease which should be treated proactively. Invasive SCC is cured by complete surgical excision. Early removal is the best precaution against potential metastases of SCC. Reduction of immunosuppression and switch to mTOR inhibitors and potentially, mycophenolate, may reduce the incidence of further SCC. Chemoprevention with the retinoid acitretin reduces the recurrence rate of SCC. The dermatological follow-up of SOTRs should be integrated into the comprehensive post-transplant care.
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PMID:Swiss clinical practice guidelines for skin cancer in organ transplant recipients. 1968 Aug 30


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