scholarly journals mTOR Cross-Talk in Cancer and Potential for Combination Therapy

Cancers ◽  
2018 ◽  
Vol 10 (1) ◽  
pp. 23 ◽  
Author(s):  
Fabiana Conciatori ◽  
Ludovica Ciuffreda ◽  
Chiara Bazzichetto ◽  
Italia Falcone ◽  
Sara Pilotto ◽  
...  
Keyword(s):  
Cross Talk ◽  
Therapeutic Strategy ◽  
Clinical Success ◽  
Single Agent ◽  
Mammalian Target Of Rapamycin ◽  
Cellular Growth ◽  
Mtor Inhibition ◽  
The Past ◽  
Exogenous Cues ◽  
Pharmacological Studies

The mammalian Target of Rapamycin (mTOR) pathway plays an essential role in sensing and integrating a variety of exogenous cues to regulate cellular growth and metabolism, in both physiological and pathological conditions. mTOR functions through two functionally and structurally distinct multi-component complexes, mTORC1 and mTORC2, which interact with each other and with several elements of other signaling pathways. In the past few years, many new insights into mTOR function and regulation have been gained and extensive genetic and pharmacological studies in mice have enhanced our understanding of how mTOR dysfunction contributes to several diseases, including cancer. Single-agent mTOR targeting, mostly using rapalogs, has so far met limited clinical success; however, due to the extensive cross-talk between mTOR and other pathways, combined approaches are the most promising avenues to improve clinical efficacy of available therapeutics and overcome drug resistance. This review provides a brief and up-to-date narrative on the regulation of mTOR function, the relative contributions of mTORC1 and mTORC2 complexes to cancer development and progression, and prospects for mTOR inhibition as a therapeutic strategy.

scholarly journals Extracellular vesicles released from the filarial parasite Brugia malayi downregulate the host mTOR pathway

2021 ◽  
Vol 15 (1) ◽  
pp. e0008884
Author(s):  
Alessandra Ricciardi ◽  
Sasisekhar Bennuru ◽  
Sameha Tariq ◽  
Sukhbir Kaur ◽  
Weiwei Wu ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Extracellular Vesicles ◽  
Regulatory Protein ◽  
Mammalian Target Of Rapamycin ◽  
Brugia Malayi ◽  
Cellular Growth ◽  
Host Cells ◽  
Host Responses ◽  
P Value ◽  
Mtor Inhibition

We have previously shown that the microfilarial (mf) stage of Brugia malayi can inhibit the mammalian target of rapamycin (mTOR; a conserved serine/threonine kinase critical for immune regulation and cellular growth) in human dendritic cells (DC) and we have proposed that this mTOR inhibition is associated with the DC dysfunction seen in filarial infections. Extracellular vesicles (EVs) contain many proteins and nucleic acids including microRNAs (miRNAs) that might affect a variety of intracellular pathways. Thus, EVs secreted from mf may elucidate the mechanism by which the parasite is able to modulate the host immune response during infection. EVs, purified from mf of Brugia malayi and confirmed by size through nanoparticle tracking analysis, were assessed by miRNA microarrays (accession number GSE157226) and shown to be enriched (>2-fold, p-value<0.05, FDR = 0.05) for miR100, miR71, miR34, and miR7. The microarray analysis compared mf-derived EVs and mf supernatant. After confirming their presence in EVs using qPCR for these miRNA targets, web-based target predictions (using MIRPathv3, TarBAse and MicroT-CD) predicted that miR100 targeted mTOR and its downstream regulatory protein 4E-BP1. Our previous data with live parasites demonstrated that mf downregulate the phosphorylation of mTOR and its downstream effectors. Additionally, our proteomic analysis of the mf-derived EVs revealed the presence of proteins commonly found in these vesicles (data are available via ProteomeXchange with identifier PXD021844). We confirmed internalization of mf-derived EVs by human DCs and monocytes using confocal microscopy and flow cytometry, and further demonstrated through flow cytometry, that mf-derived EVs downregulate the phosphorylation of mTOR in human monocytes (THP-1 cells) to the same degree that rapamycin (a known mTOR inhibitor) does. Our data collectively suggest that mf release EVs that interact with host cells, such as DC, to modulate host responses.

scholarly journals Hormone Therapy plus mTOR Inhibitors in the Treatment of Endometrial Carcinoma

2010 ◽  
Vol 9 (1) ◽  
pp. 18
Author(s):  
Erica M Stringer ◽  
Gini F Fleming ◽  
◽  
Keyword(s):  
Endometrial Cancer ◽  
Hormonal Therapy ◽  
Single Agent ◽  
Mammalian Target Of Rapamycin ◽  
Hormonal Treatment ◽  
Mtor Inhibitors ◽  
Mtor Pathway ◽  
Mtor Inhibition ◽  
Hormonal Therapies ◽  
Progestin Therapy

Hormonal therapies such as progestins have only modest activity in the treatment of advanced endometrial cancer. Mechanisms of resistance to progestin therapy are not well understood. However, activation of the PI3K/AKT/mammalian target of rapamycin (mTOR) pathway has been associated with resistance to hormonal therapy and alterations in components of the PI3K/AKT/mTOR pathway, including inactivating mutations in PTEN, activating mutations in PIK3CA and mutations in PIK3R1, are very common in endometrial carcinomas. mTOR inhibitors, including temsirolimus, everolimus and ridaforolimus, are also known to be active against endometrial cancer, and interest has been stimulated in combinations of hormonal treatment with mTOR inhibitors, as both therapies have single-agent activity, and it is hypothesised that mTOR inhibition would enhance sensitivity to hormonal therapy.

scholarly journals Enhanced Antitumor Activity with Combining Effect of mTOR Inhibition and Microtubule Stabilization in Hepatocellular Carcinoma

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Qian Zhou ◽  
Chi Hang Wong ◽  
Cecilia Pik Yuk Lau ◽  
Connie Wun Chun Hui ◽  
Vivian Wai Yan Lui ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Antitumor Activity ◽  
Growth Inhibition ◽  
Single Agent ◽  
Mammalian Target Of Rapamycin ◽  
Mechanistic Study ◽  
Dependent Manner ◽  
Mtor Inhibition

Mammalian target of rapamycin (mTOR) and the microtubules are shown to be potential targets for treating hepatocellular carcinoma (HCC). PI3K/Akt/mTOR activation is associated with resistance to microtubule inhibitors. Here, we evaluated the antitumor activity by cotargeting of the mTOR (using allosteric mTOR inhibitor everolimus) and the microtubules (using novel microtubule-stabilizing agent patupilone) in HCC models.In vitrostudies showed that either targeting mTOR signaling with everolimus or targeting microtubules with patupilone was able to suppress HCC cell growth in a dose-dependent manner. Cotargeting of the mTOR (by everolimus) and the microtubules (by patupilone, at low nM) resulted in enhanced growth inhibition in HCC cells (achieving maximal growth inhibition of 60–87%), demonstrating potent antitumor activity of this combination.In vivostudies showed that everolimus treatment alone for two weeks was able to inhibit the growth of Hep3B xenografts. Strikingly, the everolimus/patupilone combination induced a more significant antitumor activity. Mechanistic study demonstrated that this enhanced antitumor effect was accompanied by marked cell apoptosis induction and antiangiogenic activity, which were more significant than single-agent treatments. Our findings demonstrated that the everolimus/patupilone combination, which had potent antitumor activity, was a potential therapeutic strategy for HCC.

Pursuit of the Abscopal Effect

2020 ◽  
Vol 04 (04) ◽  
pp. 369-372
Author(s):  
Paul B. Romesser ◽  
Christopher H. Crane
Keyword(s):  
Tumor Immunology ◽  
Antitumor Immunity ◽  
Clinical Success ◽  
Immune Recognition ◽  
Immune Modulators ◽  
Cancer Subtypes ◽  
The Past ◽  
Tumor Irradiation ◽  
Wide Range ◽  
Tumor Recognition

AbstractEvasion of immune recognition is a hallmark of cancer that facilitates tumorigenesis, maintenance, and progression. Systemic immune activation can incite tumor recognition and stimulate potent antitumor responses. While the concept of antitumor immunity is not new, there is renewed interest in tumor immunology given the clinical success of immune modulators in a wide range of cancer subtypes over the past decade. One particularly interesting, yet exceedingly rare phenomenon, is the abscopal response, characterized by a potent systemic antitumor response following localized tumor irradiation presumably attributed to reactivation of antitumor immunity.

scholarly journals Senescence under appraisal: hopes and challenges revisited

2021 ◽  
Author(s):  
Camilla S. A. Davan-Wetton ◽  
Emanuela Pessolano ◽  
Mauro Perretti ◽  
Trinidad Montero-Melendez
Keyword(s):  
Cellular Senescence ◽  
Clinical Success ◽  
Immune Surveillance ◽  
Favourable Outcome ◽  
Cellular Growth ◽  
Therapeutic Approaches ◽  
Cycle Arrest ◽  
Therapeutic Development ◽  
The Right ◽  
Inflammation Resolution

AbstractIn recent years, cellular senescence has become the focus of attention in multiple areas of biomedical research. Typically defined as an irreversible cell cycle arrest accompanied by increased cellular growth, metabolic activity and by a characteristic messaging secretome, cellular senescence can impact on multiple physiological and pathological processes such as wound healing, fibrosis, cancer and ageing. These unjustly called ‘zombie cells’ are indeed a rich source of opportunities for innovative therapeutic development. In this review, we collate the current understanding of the process of cellular senescence and its two-faced nature, i.e. beneficial/detrimental, and reason this duality is linked to contextual aspects. We propose the senescence programme as an endogenous pro-resolving mechanism that may lead to sustained inflammation and damage when dysregulated or when senescent cells are not cleared efficiently. This pro-resolving model reconciles the paradoxical two faces of senescence by emphasising that it is the unsuccessful completion of the programme, and not senescence itself, what leads to pathology. Thus, pro-senescence therapies under the right context, may favour inflammation resolution. We also review the evidence for the multiple therapeutic approaches under development based on senescence, including its induction, prevention, clearance and the use of senolytic and senomorphic drugs. In particular, we highlight the importance of the immune system in the favourable outcome of senescence and the implications of an inefficient immune surveillance in completion of the senescent cycle. Finally, we identify and discuss a number of challenges and existing gaps to encourage and stimulate further research in this exciting and unravelled field, with the hope of promoting and accelerating the clinical success of senescence-based therapies.

Role of PRAS40 in Akt and mTOR signaling in health and disease

2012 ◽  
Vol 302 (12) ◽  
pp. E1453-E1460 ◽  
Author(s):  
Claudia Wiza ◽  
Emmani B. M. Nascimento ◽  
D. Margriet Ouwens
Keyword(s):  
Mammalian Target Of Rapamycin ◽  
Mtor Signaling ◽  
Cellular Growth ◽  
S6 Kinase ◽  
Binding Partners ◽  
Health And Disease ◽  
Mtor Complex 1 ◽  
Mtor Activity

The proline-rich Akt substrate of 40 kDa (PRAS40) acts at the intersection of the Akt- and mammalian target of rapamycin (mTOR)-mediated signaling pathways. The protein kinase mTOR is the catalytic subunit of two distinct signaling complexes, mTOR complex 1 (mTORC1) and mTORC2, that link energy and nutrients to the regulation of cellular growth and energy metabolism. Activation of mTOR in response to nutrients and growth factors results in the phosphorylation of numerous substrates, including the phosphorylations of S6 kinase by mTORC1 and Akt by mTORC2. Alterations in Akt and mTOR activity have been linked to the progression of multiple diseases such as cancer and type 2 diabetes. Although PRAS40 was first reported as substrate for Akt, investigations toward mTOR-binding partners subsequently identified PRAS40 as both component and substrate of mTORC1. Phosphorylation of PRAS40 by Akt and by mTORC1 itself results in dissociation of PRAS40 from mTORC1 and may relieve an inhibitory constraint on mTORC1 activity. Adding to the complexity is that gene silencing studies indicate that PRAS40 is also necessary for the activity of the mTORC1 complex. This review summarizes the regulation and potential function(s) of PRAS40 in the complex Akt- and mTOR-signaling network in health and disease.

scholarly journals Mammalian target of rapamycin signaling activation patterns in neuroendocrine tumors of the lung

2010 ◽  
Vol 17 (4) ◽  
pp. 977-987 ◽  
Author(s):  
Luisella Righi ◽  
Marco Volante ◽  
Ida Rapa ◽  
Veronica Tavaglione ◽  
Frediano Inzani ◽  
...  
Keyword(s):  
Neuroendocrine Tumors ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Pathway ◽  
Differential Sensitivity ◽  
Initiation Factor ◽  
Target Of Rapamycin ◽  
Low Grade ◽  
Mtor Inhibition ◽  
Signaling Activation ◽  
Activation Status

Among alternative therapeutic strategies in clinically aggressive neuroendocrine tumors (NETs) of the lung, promising results have been obtained in experimental clinical trials with mammalian target of rapamycin (mTOR) inhibitors, though in the absence of a proven mTOR signaling activation status. This study analyzed the expression of phosphorylated mTOR (p-mTOR) and its major targets, the ribosomal p70S6-kinase (S6K) and the eukaryotic initiation factor 4E-binding protein 1 (4EBP1) in a large series of 218 surgically resected, malignant lung NETs, including 24 metastasizing typical carcinoids, 73 atypical carcinoids, 60 large cell neuroendocrine carcinomas (LCNECs), and 61 small cell carcinomas (SCLCs). By immunohistochemistry, low-to-intermediate-grade tumors as compared with high-grade tumors showed higher levels of p-mTOR and phosphorylated S6K (p-S6K) (P<0.001), at variance with phosphorylated 4EBP1 (p-4EBP1), which was mainly expressed in LCNECs and SCLCs (P<0.001). The activated status of mTOR pathway was proved by the strong correlation of p-mTOR with p-S6K and somatostatin receptor(s). Western blot analysis of NET tumor samples confirmed such findings, and differential sensitivity to mTOR inhibition according to mTOR pathway activation characteristics was determined in two lung carcinoid cell lines in vitro. None of the investigated molecules had an impact on survival. However, in low-grade tumors, low p-mTOR expression correlated with lymph node metastases (P=0.016), recurrent disease, and survival (P=0.005). In conclusion, these data demonstrate a differential mTOR activation status in the spectrum of pulmonary NETs, possibly suggesting that mTOR pathway profiling might play a predictive role in candidate patients for mTOR-targeted therapies.

scholarly journals New Mammalian Target of Rapamycin (mTOR) Modulators Derived from Natural Product Databases and Marine Extracts by Using Molecular Docking Techniques

Marine Drugs ◽  
2018 ◽  
Vol 16 (10) ◽  
pp. 385 ◽  
Author(s):  
Verónica Ruiz-Torres ◽  
Maria Losada-Echeberría ◽  
Maria Herranz-López ◽  
Enrique Barrajón-Catalán ◽  
Vicente Galiano ◽  
...  
Keyword(s):  
Natural Products ◽  
Molecular Docking ◽  
Side Effects ◽  
Inhibitory Activity ◽  
Mammalian Target Of Rapamycin ◽  
Therapeutic Use ◽  
Cellular Growth ◽  
Target Of Rapamycin ◽  
Computational Techniques ◽  
Chemical Derivatives

Mammalian target of rapamycin (mTOR) is a PI3K-related serine/threonine protein kinase that functions as a master regulator of cellular growth and metabolism, in response to nutrient and hormonal stimuli. mTOR functions in two distinct complexes—mTORC1 is sensitive to rapamycin, while, mTORC2 is insensitive to this drug. Deregulation of mTOR’s enzymatic activity has roles in cancer, obesity, and aging. Rapamycin and its chemical derivatives are the only drugs that inhibit the hyperactivity of mTOR, but numerous side effects have been described due to its therapeutic use. The purpose of this study was to identify new compounds of natural origin that can lead to drugs with fewer side effects. We have used computational techniques (molecular docking and calculated ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) parameters) that have enabled the selection of candidate compounds, derived from marine natural products, SuperNatural II, and ZINC natural products, for inhibitors targeting, both, the ATP and the rapamycin binding sites of mTOR. We have shown experimental evidence of the inhibitory activity of eleven selected compounds against mTOR. We have also discovered the inhibitory activity of a new marine extract against this enzyme. The results have been discussed concerning the necessity to identify new molecules for therapeutic use, especially against aging, and with fewer side effects.

Antileukemic activity of rapamycin in acute myeloid leukemia

Blood ◽  
2005 ◽  
Vol 105 (6) ◽  
pp. 2527-2534 ◽  
Author(s):  
Christian Récher ◽  
Odile Beyne-Rauzy ◽  
Cécile Demur ◽  
Gaëtan Chicanne ◽  
Cédric Dos Santos ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
De Novo ◽  
Mammalian Target Of Rapamycin ◽  
Cell Types ◽  
Mtor Inhibition ◽  
Growth And Survival ◽  
Clinical Responses ◽  
De Novo Aml ◽  
Acute Myeloid

AbstractThe mammalian target of rapamycin (mTOR) is a key regulator of growth and survival in many cell types. Its constitutive activation has been involved in the pathogenesis of various cancers. In this study, we show that mTOR inhibition by rapamycin strongly inhibits the growth of the most immature acute myeloid leukemia (AML) cell lines through blockade in G0/G1 phase of the cell cycle. Accordingly, 2 downstream effectors of mTOR, 4E-BP1 and p70S6K, are phosphorylated in a rapamycin-sensitive manner in a series of 23 AML cases. Interestingly, the mTOR inhibitor markedly impairs the clonogenic properties of fresh AML cells while sparing normal hematopoietic progenitors. Moreover, rapamycin induces significant clinical responses in 4 of 9 patients with either refractory/relapsed de novo AML or secondary AML. Overall, our data strongly suggest that mTOR is aberrantly regulated in most AML cells and that rapamycin and analogs, by targeting the clonogenic compartment of the leukemic clone, may be used as new compounds in AML therapy.

scholarly journals A Novel 2-Carbon-Linked Dimeric Artemisinin With Potent Antileukemic Activity and Favorable Pharmacology

2022 ◽  
Vol 11 ◽  
Author(s):  
Amanda B. Kagan ◽  
Blake S. Moses ◽  
Bryan T. Mott ◽  
Ganesha Rai ◽  
Nicole M. Anders ◽  
...  
Keyword(s):  
Myeloid Leukemia ◽  
Antimalarial Activity ◽  
Single Agent ◽  
Therapeutic Window ◽  
Antileukemic Activity ◽  
Standard Chemotherapy ◽  
The Past ◽  
Or Gene ◽  
Cure Rates

Acute myeloid leukemia (AML) remains a devastating disease, with low cure rates despite intensive standard chemotherapy regimens. In the past decade, targeted antileukemic drugs have emerged from research efforts. Nevertheless, targeted therapies are often effective for only a subset of patients whose leukemias harbor a distinct mutational or gene expression profile and provide only transient antileukemic responses as monotherapies. We previously presented single agent and combination preclinical data for a novel 3-carbon-linked artemisinin-derived dimer (3C-ART), diphenylphosphate analog 838 (ART838), that indicates a promising approach to treat AML, given its demonstrated synergy with targeted antileukemic drugs and large therapeutic window. We now report new data from our initial evaluation of a structurally distinct class of 2-carbon-linked dimeric artemisinin-derived analogs (2C-ARTs) with prior documented in vivo antimalarial activity. These 2C-ARTs have antileukemic activity at low (nM) concentrations, have similar cooperativity with other antineoplastic drugs and comparable physicochemical properties to ART838, and provide a viable path to clinical development.

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