Blocking the mTOR pathway: a drug discovery perspective

2011 ◽  
Vol 39 (2) ◽  
pp. 451-455 ◽  
Author(s):  
Carlos Garcia-Echeverria
Keyword(s):  
Drug Discovery ◽  
Cancer Patients ◽  
Cancer Biology ◽  
Human Cancer ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Inhibitors ◽  
Mechanisms Of Action ◽  
Mtor Pathway ◽  
Lipid Kinase ◽  
Phosphoinositide 3 Kinase

Substantial drug discovery efforts have been devoted, over the last few years, to identifying and developing mTOR (mammalian target of rapamycin) kinase modulators. This has resulted in a number of mTOR inhibitors with different mechanisms of action and/or distinct protein and lipid kinase selectivity profiles. As briefly reviewed in the present paper, these compounds have provided us with a better understanding of the roles of mTOR and other phosphoinositide 3-kinase/mTOR pathway components in human cancer biology, and a few of them have already demonstrated clinical benefit in cancer patients.

scholarly journals Targeting AKT/mTOR in Oral Cancer: Mechanisms and Advances in Clinical Trials

2020 ◽  
Vol 21 (9) ◽  
pp. 3285 ◽  
Author(s):  
Choudhary Harsha ◽  
Kishore Banik ◽  
Hui Li Ang ◽  
Sosmitha Girisa ◽  
Rajesh Vikkurthi ◽  
...  
Keyword(s):  
Oral Cancer ◽  
Epithelial To Mesenchymal Transition ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Inhibitors ◽  
Mtor Pathway ◽  
Mtor Signaling ◽  
Therapeutic Interventions ◽  
Treatment Modalities ◽  
Disease Heterogeneity ◽  
Mesenchymal Transition

Oral cancer (OC) is a devastating disease that takes the lives of lots of people globally every year. The current spectrum of treatment modalities does not meet the needs of the patients. The disease heterogeneity demands personalized medicine or targeted therapies. Therefore, there is an urgent need to identify potential targets for the treatment of OC. Abundant evidence has suggested that the components of the protein kinase B (AKT)/ mammalian target of rapamycin (mTOR) pathway are intrinsic factors for carcinogenesis. The AKT protein is central to the proliferation and survival of normal and cancer cells, and its downstream protein, mTOR, also plays an indispensable role in the cellular processes. The wide involvement of the AKT/mTOR pathway has been noted in oral squamous cell carcinoma (OSCC). This axis significantly regulates the various hallmarks of cancer, like proliferation, survival, angiogenesis, invasion, metastasis, autophagy, and epithelial-to-mesenchymal transition (EMT). Activated AKT/mTOR signaling is also associated with circadian signaling, chemoresistance and radio-resistance in OC cells. Several miRNAs, circRNAs and lncRNAs also modulate this pathway. The association of this axis with the process of tumorigenesis has culminated in the identification of its specific inhibitors for the prevention and treatment of OC. In this review, we discussed the significance of AKT/mTOR signaling in OC and its potential as a therapeutic target for the management of OC. This article also provided an update on several AKT/mTOR inhibitors that emerged as promising candidates for therapeutic interventions against OC/head and neck cancer (HNC) in clinical studies.

The role of mTOR inhibitors in targeting a putative cancer stem cell-like population in esophageal cancer.

2016 ◽  
Vol 34 (4_suppl) ◽  
pp. 43-43
Author(s):  
Da Wang ◽  
Roland Chiu ◽  
John Theodorus Plukker ◽  
Robert P. Coppes
Keyword(s):  
Esophageal Cancer ◽  
Cell Lines ◽  
Mammalian Target Of Rapamycin ◽  
Neoadjuvant Chemoradiotherapy ◽  
Mtor Inhibitors ◽  
Mtor Pathway ◽  
Tumor Biopsy ◽  
Sphere Formation ◽  
Dose Dependent

43 Background: Despite modern advances in the treatment of esophageal cancer (EC), using neoadjuvant chemoradiotherapy (CRT) and esophagectomy, most patients face poor outcome. Growing evidence indicates that cancer stem cells (CSCs) might contribute to the poor prospects. CSCs are usually resistant to CRT and ultimately can generate a new tumor. The mammalian target of rapamycin (mTOR) pathway is associated with cancer stemness. However, its role in EC CSC-like populations needs to be elucidated. Here, we investigate the role of mTOR pathway on the stemness of a putative CSC-like population. Methods: Previously, we identified a putative CSC-like population (CD44+/CD24-) in EC cell lines and in tumor biopsy from EC patients. qPCR was used to measure the expression of mTOR in CD44+/CD24- CSC-like population of OE21 squamous cell carcinoma and OE33 adenocarcinoma cell lines compared to controls, that consisted of solid tumors generated from the same cell lines obtained from xenografts. mTOR inhibitors rapamycin and torin-1 were used to see their effect on CD44+/CD24- expression and sphere formation. Results: mTOR expression was 2-fold up-regulated in the OE33 CD44+/CD24- CSC-like population compared to control. Furthermore, in OE21 this up-regulation was 1.9-fold. Surprisingly, inhibiting the mTOR pathway with rapamycin enhanced OE33 CD44+/CD24- expression compared to its control (p = 0.01). In pilot experiments this effect was dose dependent and cells treated with rapamycin formed more spheres than control. Rapamycin did not alter the expression of CD44+/CD24- in OE21. Inhibiting the mTOR pathway with Torin-1 enhanced OE21 CD44+/CD24- expression by 1.2-fold compared to control (N = 2). In another pilot experiment Torin-1 treated cells were able to form more spheres compared to control. Torin-1 did not have an effect on the expression of CD44+/CD24- in OE33. Conclusions: These findings indicate that inhibiting the mTOR pathway may enhance CSC-like properties in EC. Additional research needs to be done to further support this hypothesis and elucidate the mechanism in this process. Furthermore, the effect of mTOR pathway inducers in EC needs to be explored.

Regulation of class III (Vps34) PI3Ks

2007 ◽  
Vol 35 (2) ◽  
pp. 239-241 ◽  
Author(s):  
Y. Yan ◽  
J.M. Backer
Keyword(s):  
Mammalian Cells ◽  
Mammalian Target Of Rapamycin ◽  
Nutrient Sensing ◽  
Class Iii ◽  
Lipid Kinase ◽  
Intracellular Targeting ◽  
Lipid Product ◽  
Important Regulator ◽  
Phosphoinositide 3 Kinase ◽  
Vacuolar Protein

The class III PI3K (phosphoinositide 3-kinase), Vps34 (vacuolar protein sorting 34), was first identified as a regulator of vacuolar hydrolase sorting in yeast. Unlike other PI3Ks, the Vps34 lipid kinase specifically utilizes phosphatidylinositol as a substrate, producing the single lipid product PtdIns3P. While Vps34 has been studied for some time in the context of endocytosis and vesicular trafficking, it has more recently been implicated as an important regulator of autophagy, trimeric G-protein signalling, and the mTOR (mammalian target of rapamycin) nutrient-sensing pathway. The present paper will focus on studies that describe the regulation of hVps34 (human Vps34) intracellular targeting and enzymatic activity in yeast and mammalian cells.

scholarly journals mTOR Controls FLIPS Translation and TRAIL Sensitivity in Glioblastoma Multiforme Cells

2005 ◽  
Vol 25 (20) ◽  
pp. 8809-8823 ◽  
Author(s):  
Amith Panner ◽  
C. David James ◽  
Mitchel S. Berger ◽  
Russell O. Pieper
Keyword(s):  
Glioblastoma Multiforme ◽  
Mammalian Target Of Rapamycin ◽  
Death Receptor ◽  
Mtor Inhibitors ◽  
Mtor Pathway ◽  
Inhibitory Protein ◽  
Trail Resistance ◽  
Human Gbm ◽  
Induced Apoptosis ◽  
Trail Sensitivity

ABSTRACT The tumor-selective, proapoptotic, death receptor ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a mediator of antitumor drug activity and in itself is a promising agent for the treatment of human malignancies. Like many tumors, however, glioblastoma multiforme (GBM), the most fatal form of glioma, exhibits a range of TRAIL sensitivity, and only a small percentage of GBM tumors undergo TRAIL-induced apoptosis. We here show that TRAIL resistance in GBM is a consequence of overexpression of the short isoform of the caspase-8 inhibitor, c-FLICE inhibitory protein (FLIPS), and that FLIPS expression is in turn translationally enhanced by activation of the Akt-mammalian target of rapamycin (mTOR)-p70 S6 kinase 1 (S6K1) pathway. Conversely, pharmacologic or genetic inhibition of mTOR, or the mTOR target S6K1, suppresses polyribosomal accumulation of FLIPS mRNA, FLIPS protein expression, and TRAIL resistance. In archived material from 12 human GBM tumors, PTEN status was a predictor of activation of the Akt-mTOR-S6K1 pathway and of FLIPS levels, while in xenografted human GBM, activation status of the PTEN-Akt-mTOR pathway distinguished the tumors inherently sensitive to TRAIL from those which could be sensitized by the mTOR inhibitor rapamycin. These results define the mTOR pathway as a key limiter of tumor elimination by TRAIL-mediated mechanisms, provide a means by which the TRAIL-sensitive subset of GBM can be identified, and provide rationale for the combined use of TRAIL with mTOR inhibitors in the treatment of human cancers.

scholarly journals Bioactive PI3-kinase/Akt/mTOR Inhibitors in Targeted Lung Cancer Therapy

2021 ◽  
Author(s):  
Somayyeh Ghareghomi ◽  
Vahideh Atabaki ◽  
Naseh Abdollahzadeh ◽  
Shahin Ahmadian ◽  
Salar Hafez Ghoran
Keyword(s):  
Lung Cancer ◽  
Natural Products ◽  
Cancer Therapy ◽  
Cancer Cells ◽  
Human Cancer ◽  
Mtor Inhibitors ◽  
Mtor Pathway ◽  
New Drugs ◽  
Down Regulation ◽  
Lung Cancer Therapy

One of the central signaling pathways with a regulatory effect on cell proliferation and survival is Akt/mTOR. In many human cancer types, for instance, lung cancer, the overexpression of Akt/mTOR has been reported. For this reason, either targeting cancer cells by synthetic or natural products affecting the Akt/mTOR pathway down-regulation is a useful strategy in cancer therapy. Direct inhibition of the signaling pathway or modulation of each related molecule could have significant feedback on the growth and proliferation of cancer cells. A variety of secondary metabolites has been identified to directly inhibit the AKT/mTOR signaling, which is important in the field of drug discovery. Naturally occurring nitrogenous and phenolic compounds can emerge as two pivotal classes of natural products possessing anticancer abilities. Herein, we have summarized the alkaloids and flavonoids for lung cancer treatment together with all the possible mechanisms of action relying on the Akt/mTOR pathway down-regulation. This review suggested that in search of new drugs, phytochemicals could be considered as promising scaffolds to be developed into efficient drugs for the treatment of cancer. In this review, the terms "Akt/mTOR", "Alkaloid", "flavonoid", and "lung cancer" were searched without any limitation in search criteria in Scopus, PubMed, Web of Science, and Google scholar engines.

scholarly journals The Cross Talk Between p53 and mTOR Pathways in Response to Physiological and Genotoxic Stresses

2021 ◽  
Vol 9 ◽  
Author(s):  
Danrui Cui ◽  
Ruirui Qu ◽  
Dian Liu ◽  
Xiufang Xiong ◽  
Tingbo Liang ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Current Knowledge ◽  
Human Cancer ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Pathway ◽  
Tumor Suppressor P53 ◽  
Induce Cell Cycle Arrest ◽  
Downstream Effectors ◽  
Cellular Stresses

The tumor suppressor p53 is activated upon multiple cellular stresses, including DNA damage, oncogene activation, ribosomal stress, and hypoxia, to induce cell cycle arrest, apoptosis, and senescence. Mammalian target of rapamycin (mTOR), an evolutionarily conserved serine/threonine protein kinase, serves as a central regulator of cell growth, proliferation, and survival by coordinating nutrients, energy, growth factors, and oxygen levels. p53 dysfunction and mTOR pathway hyperactivation are hallmarks of human cancer. The balance between response to stresses or commitment to cell proliferation and survival is governed by various regulatory loops between the p53 and mTOR pathways. In this review, we first briefly introduce the tumor suppressor p53 and then describe the upstream regulators and downstream effectors of the mTOR pathway. Next, we discuss the role of p53 in regulating the mTOR pathway through its transcriptional and non-transcriptional effects. We further describe the complicated role of the mTOR pathway in modulating p53 activity. Finally, we discuss the current knowledge and future perspectives on the coordinated regulation of the p53 and mTOR pathways.

scholarly journals Recent Updates on the Involvement of PI3K/AKT/mTOR Molecular Cascade in the Pathogenesis of Hyperproliferative Skin Disorders

2021 ◽  
Vol 8 ◽  
Author(s):  
Laura Mercurio ◽  
Cristina Albanesi ◽  
Stefania Madonna
Keyword(s):  
Cell Carcinoma ◽  
Mammalian Cells ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Pathway ◽  
Mtor Signaling ◽  
Keratinocyte Differentiation ◽  
Current Status ◽  
Regulatory Subunit ◽  
Skin Disorders ◽  
Phosphoinositide 3 Kinase

PhosphoInositide-3 Kinase (PI3K) represents a family of different classes of kinases which control multiple biological processes in mammalian cells, such as cell growth, proliferation, and survival. Class IA PI3Ks, the main regulators of proliferative signals, consists of a catalytic subunit (α, β, δ) that binds p85 regulatory subunit and mediates activation of AKT and mammalian Target Of Rapamycin (mTOR) pathways and regulation of downstream effectors. Dysregulation of PI3K/AKT/mTOR pathway in skin contributes to several pathological conditions characterized by uncontrolled proliferation, including skin cancers, psoriasis, and atopic dermatitis (AD). Among cutaneous cancers, basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) display PI3K/AKT/mTOR signaling hyperactivation, implicated in hyperproliferation, and tumorigenesis, as well as in resistance to apoptosis. Upregulation of mTOR signaling proteins has also been reported in psoriasis, in association with enhanced proliferation, defective keratinocyte differentiation, senescence-like growth arrest, and resistance to apoptosis, accounting for major parts of the overall disease phenotypes. On the contrary, PI3K/AKT/mTOR role in AD is less characterized, even though recent evidence demonstrates the relevant function for mTOR pathway in the regulation of epidermal barrier formation and stratification. In this review, we provide the most recent updates on the role and function of PI3K/AKT/mTOR molecular axis in the pathogenesis of different hyperproliferative skin disorders, and highlights on the current status of preclinical and clinical studies on PI3K-targeted therapies.

Risk of pneumonitis with mammalian target of rapamycin (mTOR) inhibitors everolimus and temsirolimus.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e13573-e13573
Author(s):  
Vishal Navnitray Ranpura ◽  
Shenhong Wu
Keyword(s):  
Clinical Trials ◽  
Cancer Patients ◽  
Meta Analysis ◽  
Single Agent ◽  
Mammalian Target Of Rapamycin ◽  
Cancer Therapeutics ◽  
Mtor Inhibitors ◽  
High Grade ◽  
Significant Difference ◽  
American Society

e13573 Background: Pneumonitis is associated with the use of mTOR inhibitors, everolimus and temsirolimus, which have been used widely in cancer therapeutics and clinical trials. Currently, the overall risk of pneumonits in patients treated with mTOR inhibitors has not been defined. We performed a systematic review and meta-analysis of published clinical trials to assess the risk of pneumonitis in cancer patients treated with mTOR inhibitors. Methods: Databases from PUBMED, the Web of Science, and abstracts presented at the American Society of Clinical Oncology conferences until May 2012 were searched to identify relevant studies. Eligible studies included prospective clinical trials in which patients received treatment with everolimus or temsirolimus as a single agent or in combination with other agents. Summary incidence, relative risk (RR), and 95% confidence interval (CI) were calculated employing a fixed- or random-effects model based upon the heterogeneity of the included studies. Results: A total of 2,303 patients with a variety of tumors from 18 studies (everolimus: 12, temsirolimus: 6) were included for the analysis. The overall incidences of all-grade and high-grade pneumonitis with mTOR inhibitors were 6.5% (95% CI: 3.7-11.1%) and 2.5% (95% CI 1.2-5.4%) respectively. The risk of all-grade pneumonitis did not vary significantly with tumor types (P=0.079), but vary significantly with their combination with other agents (P<0.001). There was no significant difference between everolimus and temsirolimus in the incidence of all-grade (P=0.22) and high-grade (P=0.28) pneumonitis. In comparison with controls, mTOR inhibitors significantly increased the risk of all-grade (RR=5.2, 95% CI: 2.09-12.93, P<0.001) but not high-grade pneumonits (RR=2.63, 95% CI: 0.66-10.40, P=0.41). Conclusions: The risk of pneumonitis is increased in cancer patients receiving mTOR inhibitors without significant difference between everolimus and temsirolimus.

Akt is efficiently activated by PIF-pocket- and PtdIns(3,4,5)P3-dependent mechanisms leading to resistance to PDK1 inhibitors

2012 ◽  
Vol 448 (2) ◽  
pp. 285-295 ◽  
Author(s):  
Ayaz Najafov ◽  
Natalia Shpiro ◽  
Dario R. Alessi
Keyword(s):  
Cell Lines ◽  
Therapeutic Strategy ◽  
Mammalian Target Of Rapamycin ◽  
Significant Proportion ◽  
Mtor Inhibitors ◽  
Akt Activation ◽  
Akt Isoforms ◽  
Anti Cancer ◽  
Phosphoinositide 3 Kinase ◽  
Loop Residue

Mutations leading to inappropriate activation of Akt isoforms contribute to proliferation and survival of a significant proportion of human cancers. Akt is activated by phosphorylation of its T-loop residue (Thr308) by PDK1 (3-phosphoinositide-dependent kinase-1) and its C-terminal hydrophobic motif (Ser473) by mTORC2 [mTOR (mammalian target of rapamycin) complex 2]. Potent PDK1 inhibitors such as GSK2334470 have recently been elaborated as potential anti-cancer agents. However, these compounds were surprisingly ineffective at suppressing Akt activation. In the present study we demonstrate that resistance to PDK1 inhibitors results from Akt being efficiently recruited to PDK1 via two alternative mechanisms. The first involves ability of Akt and PDK1 to mutually interact with the PI3K (phosphoinositide 3-kinase) second messenger PtdIns(3,4,5)P3. The second entails recruitment of PDK1 to Akt after its phosphorylation at Ser473 by mTORC2, via a substrate-docking motif termed the PIF-pocket. We find that disruption of either the PtdIns(3,4,5)P3 or the Ser473 phosphorylation/PIF-pocket mechanism only moderately impacts on Akt activation, but induces marked sensitization to PDK1 inhibitors. These findings suggest that suppression of Ser473 phosphorylation by using mTOR inhibitors would disrupt the PIF-pocket mechanism and thereby sensitize Akt to PDK1 inhibitors. Consistent with this, we find combing PDK1 and mTOR inhibitors reduced Akt activation to below basal levels and markedly inhibited proliferation of all of the cell lines tested. Our results suggest further work is warranted to explore the utility of combining PDK1 and mTOR inhibitors as a therapeutic strategy for treatment of cancers that harbour mutations elevating Akt activity.

Sign in / Sign up

Export Citation Format

Share Document