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)

Multiple molecular, cellular, micro-environmental and systemic causes of anticancer drug resistance have been identified during the last 25 years. At the same time, genome-wide analysis of human tumor tissues has made it possible in principle to assess the expression of critical genes or mutations that determine the response of an individual patient's tumor to drug treatment. Why then do we, with a few exceptions, such as mutation analysis of the EGFR to guide the use of EGFR inhibitors, have no predictive tests to assess a patient's drug sensitivity profile. The problem urges the more with the expanding choice of drugs, which may be beneficial for a fraction of patients only. In this review we discuss recent studies and insights on mechanisms of anticancer drug resistance and try to answer the question: do we understand why a patient responds or fails to respond to therapy? We focus on doxorubicin as example of a classical cytotoxic, DNA damaging agent and on sunitinib, as example of the new generation of (receptor) tyrosine kinase-targeted agents. For both drugs, classical tumor cell autonomous resistance mechanisms, such as drug efflux transporters and mutations in the tumor cell's survival signaling pathways, as well as micro-environment-related resistance mechanisms, such as changes in tumor stromal cell composition, matrix proteins, vascularity, oxygenation and energy metabolism may play a role. Novel agents that target specific mutations in the tumor cell's damage repair (e.g. PARP inhibitors) or that target tumor survival pathways, such as Akt inhibitors, glycolysis inhibitors or mTOR inhibitors, are of high interest. In order to increase the therapeutic index of treatments, fine-tuned synergistic combinations of new and/or classical cytotoxic agents will be designed. More quantitative assessment of potential resistance mechanisms in real tumors and in real time, such as by kinase profiling methodology, will be developed to allow more precise prediction of the optimal drug combination to treat each patient.
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PMID:Understanding the causes of multidrug resistance in cancer: a comparison of doxorubicin and sunitinib. 1964 52

Breast cancer is a heterogeneous disease characterised by a dysregulation of multiple pathways related to cell differentiation, cell cycle control, apoptosis, angiogenesis and development of metastasis. Acting against these pathways provides therapeutic targets for new targeted biologic therapies, which, in the future, might constitute a key for fighting cancer. The development of molecular technology in recent years has allowed a further comprehension of these mutations and dysregulated pathways leading to oncogenesis. New targeted biologic therapies will block essential functions of cancer cells and tumour stroma. A growing number of therapy options, alone or in combination with background treatments (chemotherapy, hormone therapy, radiotherapy), will allow oncologists a better adaptation of treatment to patients and disease characteristics. Examples of approved targeted agents in breast cancer include agents targeting the human epidermal growth factor receptor 2 (HER2), such as trastuzumab, lapatinib and the anti-VEGF bevacizumab. In addition, there are other therapy classes under evaluation, including novel antiEGFR or antiHER2 therapies; agents fighting other tyrosine kinases, including the Src and the insulinlike growth factor receptor; agents interfering critically relevant pathways, such as PI3K/AKT/mTOR inhibitors; and agents promoting apoptosis, such as PARP inhibitors (for particular breast cancer subtypes, such as basal-like, or breast cancer with BRCA mutations) and others. The better selectivity against malignant cells of these therapies, when compared to conventional chemotherapy, gives, a priori, at least two advantages to biologic treatments: fewer side effects and a more individualised treatment of cancer depending on the tumour's molecular characteristics. The ability to identify patients' subgroups and response predicting factors will be crucial in obtaining the greatest benefit with minimal toxicity levels. Unsolved questions remain, such as appropriate patient selection based on the expression of the therapeutic target in the tumour, the study of the efficacy of the drug in not so extensively pretreated populations and with a greater chance of response, the use of new pharmacodynamic models to help to define new response predicting factors for a specific new biologic therapy, the combined and rational use of different biologic therapies having different molecular targets and fighting the same target through a complementary mechanism of action that might improve clinical efficacy.
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PMID:Targeted therapy of metastatic breast cancer. 1982 6

YC-1 has recently been demonstrated to have potent anti-invasion and anti-metastatic activity in several cancer models, in addition to its anti-proliferation activity. However, the mechanism underlying its anti-invasion/anti-metastatic activity is largely unknown. Nasopharyngeal carcinoma (NPC) is a highly metastatic head and neck cancer in Southeast Asia. Here, we demonstrated that YC-1 inhibited invasiveness and proliferation of NPC cells, with the latter being accompanied by PARP cleavage, S-phase arrest and activation of Chk1/Chk2. We aimed at identifying novel anti-invasion mechanisms of YC-1 in NPC by a functional proteomic platform, the reverse phase protein array (RPPA). Our study revealed for the first time that multiple invasion-related signaling proteins (beta-catenin, caveolin, Src and EGFR), as well as several growth-related proteins (AMPKalpha, phospho-acetyl-CoA carboxylase (p-ACC), HER-2 and mTOR), which were previously un-described signaling proteins altered by YC-1, were found to be down-modulated by YC-1 in NPC cells. We hypothesized that YC-1-mediated downregulation of these invasion proteins contributed to its anti-invasion activity in NPC cells. Overexpression of EGFR, activated Src or caveolin, but not beta-catenin reversed the inhibitory effects of YC-1 on NPC cell invasion, with EGFR and activated Src having additional effects on rescuing NPC cells from YC-1-mediated growth inhibition. In summary, we have identified several novel anti-invasion mechanisms of YC-1 that could impact NPC, and possibly other cancers as well.
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PMID:Reverse phase protein array identifies novel anti-invasion mechanisms of YC-1. 1987 57

Ovarian cancers are the leading cause of death from gynaecological malignancies in Western countries. Despite optimal treatment combining surgery and chemotherapy, relapse is observed in the majority of patients. This review aims to present the results of trials having evaluated new drugs in ovarian cancers. Advances in the understanding of cancer biology and more specifically of cell signalling pathways have led to the identification of several potential molecular targets and to the development of new agents directed against these targets. The assessment of targeted therapies is relatively recent in this field. So far, only the results of phase II trials have been published, but many phase III trials are underway. Some targets (HER-2, EGFR) initially regarded as promising have already been abandoned due to the lack of results. The most advanced molecular therapies target angiogenesis (VEGF, VEFGR). PARP and mTOR inhibitors may also represent a significant therapeutic improvement. It remains to confirm the interest of these new approaches by assessing the benefit on overall survival. The goal remains to individualize and to tailor the drugs to the tumour biology, in order to provide personalized treatment to each patient.
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PMID:[New drugs and targeted therapeutic agents in ovarian cancer]. 1991 16

NVP-BEZ235 is a dual PI3K/mTOR inhibitor currently in phase I clinical trials. We profiled this compound against a panel of breast tumor cell lines to identify the patient populations that would benefit from such treatment. In this setting, NVP-BEZ235 selectively induced cell death in cell lines presenting either HER2 amplification and/or PIK3CA mutation, but not in cell lines with PTEN loss of function or KRAS mutations, for which resistance could be attributed, in part to ERK pathway activity. An in depth analysis of death markers revealed that the cell death observed upon NVP-BEZ235 treatment could be recapitulated with other PI3K inhibitors and that this event is linked to active PARP cleavage indicative of an apoptotic process. Moreover, the effect seemed to be partly independent of the caspase-9 executioner and mitochondrial activated caspases, suggesting an alternate route for apoptosis induction by PI3K inhibitors. Overall, this study will provide guidance for patient stratification for forthcoming breast cancer phase II trials for NVP-BEZ235.
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PMID:Specific apoptosis induction by the dual PI3K/mTor inhibitor NVP-BEZ235 in HER2 amplified and PIK3CA mutant breast cancer cells. 2000 81

Malignant pleural mesothelioma (MPM) is an aggressive, rapidly progressive malignancy without effective therapy. We evaluate sorafenib efficacy and impact on the cellular pro-survival machinery in vitro, efficacy of sorafenib as monotherapy and in combination with the naturally occurring death receptor agonist, TRAIL using human MPM cell lines, MSTO-211H, M30, REN, H28, H2052 and H2452. In vitro studies of the six MPM lines demonstrated single agent sensitivity to the multikinase inhibitor sorafenib and resistance to TRAIL. H28 and H2452 demonstrated augmented apoptosis with the addition of TRAIL to sorafenib in vitro. Treated cell lines demonstrated sorafenib-induced rapid dephosphorylation of AKT followed shortly by near complete dephosphorylation of the constitutively phosphorylated ERK1/2. Sorafenib therapy also decreased phosphorylation of B-Raf and mTOR in several cell lines. Within 3 h of sorafenib treatment, a number of known pro-survival molecules were dephosphorylated and/or downregulated in expression including MCL-1(L), c-FLIP(L), survivin and cIAP(1). These changes and eventual cell death did not elicit significant caspase-3 activation or PARP cleavage and pretreatment with the pan-caspase inhibitor, Z-VAD-FMK, did not block sorafenib efficacy but did block the effect of TRAIL monotherapy. Pre-treatment with Z-VAD-FMK did not block the synergistic effect of TRAIL and sorafenib in H28. In summary, single agent treatment with sorafenib results in widespread inhibition of the pro-survival machinery in vitro leading to cell death via a primarily caspase-independent mechanism. Combining sorafenib therapy with TRAIL, may be useful in order to provide a more efficient death signal and this synergistic effect appears to be caspase-independent. Pilot in vivo data demonstrates promising evidence of therapeutic efficacy in human tumor bearing xenograft nu/nu mice. We document single agent activity of sorafenib against MPM, unravel novel effects of sorafenib on anti-apoptotic signaling mediators, and suggest the combination of sorafenib plus TRAIL as possible therapy for clinical testing in MPM.
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PMID:Sorafenib inhibits ERK1/2 and MCL-1(L) phosphorylation levels resulting in caspase-independent cell death in malignant pleural mesothelioma. 2003 16

Breast cancer is a heterogeneous disease with different molecular drivers regulating its growth, survival and response to therapy. Breast cancer is divided in three major subtypes based on the pattern of expression of hormone receptors and HER2: luminal tumors (or HR positive), HER2 amplified tumors, and the remaining subtypes being collectively referred to as triple-negative breast cancer. While tumors within these subtypes have similar gene-expression patterns, clinical outcomes, and response to therapy, this division is far from perfect and subgroups within these groups are beginning to be identified. In terms of therapy, an increasingly rational drug development effort has resulted in agents against new molecular targets that are active against only those tumors with the targeted molecular alteration or phenotype. These agents include receptor and non-receptor tyrosine kinase inhibitors (HER1, HER2, HER3, insulin-like growth factor receptor, c-met, fibroblast growth factor receptor and HSP 90 inhibitors), intracellular signaling pathways (PI3K, AKT, mTOR), angiogenesis inhibitors and agents that interfere with DNA repair (PARP inhibitors). Thus, the overall management of breast cancer will increasingly require an understanding of breast cancer heterogeneicity, the biological nature of any given tumor as well the existence of increased personalized treatment options.
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PMID:Management of breast cancer with targeted agents: importance of heterogeneity. [corrected]. 2012 90

PKI-402 is a selective, reversible, ATP-competitive, equipotent inhibitor of class I phosphatidylinositol 3-kinases (PI3K), including PI3K-alpha mutants, and mammalian target of rapamycin (mTOR; IC(50) versus PI3K-alpha = 2 nmol/L). PKI-402 inhibited growth of human tumor cell lines derived from breast, brain (glioma), pancreas, and non-small cell lung cancer tissue and suppressed phosphorylation of PI3K and mTOR effector proteins (e.g., Akt at T308) at concentrations that matched those that inhibited cell growth. In MDA-MB-361 [breast: Her2(+) and PIK3CA mutant (E545K)], 30 nmol/L PKI-402 induced cleaved poly(ADP-ribose) polymerase (PARP), a marker for apoptosis. In vivo, PKI-402 inhibited tumor growth in MDA-MB-361, glioma (U87MG), and lung (A549) xenograft models. In MDA-MB-361, PKI-402 at 100 mg/kg (daily for 5 days, one round) reduced initial tumor volume of 260 mm(3) to 129 mm(3) and prevented tumor regrowth for 70 days. In MDA-MB-361 tumors, PKI-402 (100 mg/kg, single dose) suppressed Akt phosphorylation (at T308) and induced cleaved PARP. Suppression of phosphorylated Akt (p-Akt) was complete at 8 hours and still evident at 24 hours. Cleaved PARP was evident at 8 and 24 hours. In normal tissue (heart and lung), PKI-402 (100 mg/kg) had minimal effect on p-Akt, with no detectable cleaved PARP. Preferential accumulation of PKI-402 in tumor tissue was observed. Complete, sustained suppression of Akt phosphorylation may cause tumor regression in MDA-MB-361 and other xenograft models. We are testing whether dual PI3K/mTOR inhibitors can durably suppress p-Akt, induce cleaved PARP, and cause tumor regression in a diverse set of human tumor xenograft models. Mol Cancer Ther; 9(4); 976-84. (c)2010 AACR.
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PMID:Antitumor efficacy profile of PKI-402, a dual phosphatidylinositol 3-kinase/mammalian target of rapamycin inhibitor. 2037 16

Both Notch signaling and Akt-mTOR signaling pathway are involved in glioma cell proliferation and survival. Previous studies have shown that Notch-1 is overexpressed in many glioma cell lines and primary human gliomas. Blocking of Notch signaling pathway can induces glioma cell apoptosis and growth suppression. However, the underlying molecular mechanism is not clear. We report that activation of the Notch pathway by intracellular domain of human Notch-1 (NIC-1) strongly activates Akt and promotes U251 glioma cell proliferation. Knockdown of Notch-1 by RNA interference suppresses Akt activation, reduces glioma cell growth rate and induce cell apoptosis. Following Notch-1 suppression, phosphorylated Akt and its downstream effector mTOR were reduced. Knockdown of Notch-1 also involves down-regulation of anti-apoptotic protein MCL-1, in parallel with activation of apoptotic associate proteins PARP, caspase-9 and caspase-3. Our data demonstrate that Notch-1 can positively regulate Akt-mTOR pathways, which is associated with glioma cell proliferation and apoptosis. This also suggests a molecular mechanism for the inhibitory effect of Notch-1 RNA interference on glioma cell proliferation through Akt-mTOR signaling pathway.
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PMID:Akt-mTOR signaling is involved in Notch-1-mediated glioma cell survival and proliferation. 2037 62

Mammalian target of rapamycin (mTOR) signaling has been associated with aggressive tumor growth in many cancer models, although its role in urothelial carcinoma (UCC) has not been extensively explored. Expression of phosphorylated mTOR (P-mTOR) and a downstream target, ribosomal S6 protein (P-S6), was identified in 74% (90/121) and 55% (66/121) of muscle-invasive UCCs, respectively. P-mTOR intensity and %positive cells were associated with reduced disease-specific survival (P = 0.04, P = 0.08, respectively). Moreover, P-mTOR intensity corresponded to increased pathological stage (P < 0.01), and mTOR activity was associated with cell migration in vitro. In addition, mTOR inhibition via rapamycin administration reduced cell proliferation in UCC cell lines RT4, T24, J82, and UMUC3 in a dose-dependent manner to 6% of control levels and was significant at 1 nmol/L in J82, T24, and RT4 cells (P < 0.01, P < 0.01, P = 0.03, respectively) and at 10 nmol/L in UMUC3 cells (P = 0.03). Reduced proliferation corresponded with reduced P-S6 levels by Western blot, and effects were ablated by pretreatment of cells with mTOR-specific siRNA. No effects of rapamycin on apoptosis were identified by TUNEL labeling or PARP cleavage. Administration of rapamycin to T24-xenografted mice resulted in a 55% reduction in tumor volume (P = 0.03) and a 40% reduction in proliferation (P < 0.01) compared with vehicle-injected mice. These findings indicate that mTOR pathway activation frequently occurs in UCC and that mTOR inhibition may be a potential means to reduce UCC growth.
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PMID:Mammalian target of rapamycin (mTOR) regulates cellular proliferation and tumor growth in urothelial carcinoma. 2039 40


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