Mammalian target of rapamycin (mTOR) is an atypical protein kinase that controls growth and metabolism in response to nutrients, growth factors and cellular energy levels, and it is frequently dysregulated in cancer and metabolic disorders. Rapamycin is an allosteric inhibitor of mTOR, and was approved as an immuno-suppressant in 1999. In recent years, interest has focused on its potential as an anticancer drug. However, the performance of rapamycin and its analogues (rapalogues) has been undistinguished despite isolated successes in subsets of cancer, suggesting that the full therapeutic potential of targeting mTOR has yet to be exploited. A new generation of ATP-competitive inhibitors that directly target the mTOR catalytic site display potent and comprehensive mTOR inhibition and are in early clinical trials.

Rapamycin passes the torch: a new generation of mTOR inhibitors

// James A. McCubrey 1 , Linda S. Steelman 1 , William H. Chappell 1 , Stephen L. Abrams 1 , Richard A. Franklin 1 , Giuseppe Montalto 2 , Melchiorre Cervello 3 , Massimo Libra 4 , Saverio Candido 4 , Grazia Malaponte 4 , Maria C. Mazzarino 4 , Paolo Fagone 4 , Ferdinando Nicoletti 4 , Jorg Basecke 5 , Sanja Mijatovic 6 , Danijela Maksimovic-Ivanic 6 , Michele Milella 7 , Agostino Tafuri 8 , Francesca Chiarini 9 , Camilla Evangelisti 9 , Lucio Cocco 10 , Alberto M. Martelli 9,10 1 Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC, USA 2 Department of Internal Medicine and Specialties, University of Palermo, Palermo, Italy 3 Consiglio Nazionale delle Ricerche, Istituto di Biomedicina e Immunologia Molecolare “Alberto Monroy”, Palermo, Italy 4 Department of Bio-Medical Sciences, University of Catania, Catania, Italy 5 Department of Medicine, University of Gottingen, Gottingen, Germany 6 Department of Immunology, Instititue for Biological Research “Sinisa Stankovic”, University of Belgrade, Belgrade, Serbia 7 Regina Elena National Cancer Institute, Rome, Italy 8 Sapienza, University of Rome, Department of Cellular Biotechnology and Hematology, Rome, Italy 9 Institute of Molecular Genetics, National Research Council-Rizzoli Orthopedic Institute, Bologna, Italy 10 Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy Correspondence: James A. McCubrey, email: // Keywords : Targeted Therapy, Therapy Resistance, Cancer Stem Cells, Raf, Akt, PI3K, mTOR Received : September 12, 2012, Accepted : October 18, 2012, Published : October 20, 2012 Abstract The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Targeting these pathways is often complex and can result in pathway activation depending on the presence of upstream mutations (e.g., Raf inhibitors induce Raf activation in cells with wild type (WT) RAF in the presence of mutant, activated RAS ) and rapamycin can induce Akt activation. Targeting with inhibitors directed at two constituents of the same pathway or two different signaling pathways may be a more effective approach. This review will first evaluate potential uses of Raf, MEK, PI3K, Akt and mTOR inhibitors that have been investigated in pre-clinical and clinical investigations and then discuss how cancers can become insensitive to various inhibitors and potential strategies to overcome this resistance.

Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR Cascade Inhibitors: How Mutations Can Result in Therapy Resistance and How to Overcome Resistance

http://csmres.co.uk/cs.public.upd/article-downloads/2011-57471.pdf

Targeting the mTOR kinase domain: the second generation of mTOR inhibitors

The mechanistic target of rapamycin (mTOR), via its two distinct multiprotein complexes, mTORC1 and mTORC2, plays a central role in the regulation of cellular growth, metabolism and migration. A dysregulation of the mTOR pathway has in turn been implicated in several pathological conditions including insulin resistance and cancer. Overactivation of mTORC1 and disruption of mTORC2 function have been reported to induce insulin resistance. On the other hand, aberrant mTORC1 and mTORC2 signaling via either genetic alterations or increased expression of proteins regulating mTOR and its downstream targets have contributed to cancer development. These underlined the attractiveness of mTOR as a therapeutic target to overcome both insulin resistance and cancer. This review summarises the evidence supporting the notion of intermittent, low dose rapamycin for treating insulin resistance. It further highlights recent data on the continuous use of high dose rapamycin analogs and related second generation mTOR inhibitors for cancer eradication, for overcoming chemoresistance and for tumour stem cell suppression. Within these contexts, the potential challenges associated with the use of mTOR inhibitors are also discussed.

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Judicious Toggling of mTOR Activity to Combat Insulin Resistance and Cancer: Current Evidence and Perspectives

Phosphatidylinositol 3-kinases (PI3Ks) and phosphatidylinositol 3-kinase-related protein kinases (PIKKs) are two related families of kinases that play key roles in regulation of cell proliferation, metabolism, migration, survival, and responses to diverse stresses including DNA damage. To design novel efficient strategies for treatment of cancer and other diseases, these kinases have been extensively studied. Despite their different nature, these two kinase families have related origin and share very similar kinase domains. Therefore, chemical inhibitors of these kinases usually carry analogous structural motifs. The most common feature of these inhibitors is a critical hydrogen bond to morpholine oxygen, initially present in the early nonspecific PI3K and PIKK inhibitor 3 (LY294002), which served as a valuable chemical tool for development of many additional PI3K and PIKK inhibitors. While several PI3K pathway inhibitors have recently shown promising clinical responses, inhibitors of the DNA damage-relat...

Phosphatidylinositol 3-Kinase (PI3K) and Phosphatidylinositol 3-Kinase-Related Kinase (PIKK) Inhibitors: Importance of the Morpholine Ring

The phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt)-mammalian target of rapamycin (mTOR) signaling pathway is often constitutively activated in various human cancers, providing validated targets for cancer therapy. Among a series of 5-cyano-6-morpholino-4-substituted-pyrimidine analogs designed and synthesized based on PI3K target, 4-(2-(dimethylamino)vinyl)-2-(3-hydroxyphenyl)-6-morpholinopyrimidine-5-carbonitrile (WJD008) was selected for further pharmacological characterization because of its potent activity against PI3K signaling. WJD008 inhibited kinase activity of PI3Kalpha and mTOR with less activity against PIKK family members. In cellular settings, WJD008 abrogated insulin-like growth factor-I-activated PI3K-Akt-mTOR signaling cascade and blocked the membrane translocation of a pleckstrin homology domain containing enhanced green fluorescent protein-general receptor for phosphoinositides, isoform 1-pleckstrin homology fusion protein, suggesting down-regulation of phosphatidylinositol (3,4,5)-trisphosphate output induced by WJD008 resulted in inactivation of PI3K pathway. Consequently, WJD008 arrested cells in G(1) phase without induction of apoptosis. Furthermore, WJD008 reversed the hyperactivation of the PI3K pathway caused by the oncogenic mutation of p110alpha H1047R and suppressed the proliferation and clonogenesis of transformed RK3E cells harboring this mutant. WJD008 was superior to the pan-PI3K inhibitor wortmannin against proliferation of a panel of cancer cells independently of their status of PI3K pathway or tissue originations. In summary, WJD008 is a potent dual PI3K/mTOR modulator with antiproliferative and anticlonogenic activity in tumor cells and transformed cells with PIK3CA mutant, which provides new clues for the design and development of this chemical scaffold as an anticancer drug.

https://jpet.aspetjournals.org/content/jpet/early/2010/06/03/jpet.110.167940.full.pdf

WJD008, a Dual Phosphatidylinositol 3-Kinase (PI3K)/Mammalian Target of Rapamycin Inhibitor, Prevents PI3K Signaling and Inhibits the Proliferation of Transformed Cells with Oncogenic PI3K Mutant

Discovery and bioactivity of 4-(2-arylpyrido[3′,2′:3,4]pyrrolo[1,2-f][1,2,4]triazin-4-yl) morpholine derivatives as novel PI3K inhibitors

The invention relates to a novel dual inhibitor of phosphatidylinositol-3 kinase and rapamycin target protein, a preparation method and application of the dual inhibitor, in particular to a pyrido-pyrrole triazine compound with a structure shown in general formula I. a preparation method of the compound and application of the compound as a dual inhibitor of phosphatidylinositol-3 kinase and rapamycin target protein in preparation medicines for treating phosphatidylinositol-3 kinase related diseases such as tumors.

Jia Wang

Papers

WJD008, a Dual Phosphatidylinositol 3-Kinase (PI3K)/Mammalian Target of Rapamycin Inhibitor, Prevents PI3K Signaling and Inhibits the Proliferation of Transformed Cells with Oncogenic PI3K Mutant

Discovery and bioactivity of 4-(2-arylpyrido[3′,2′:3,4]pyrrolo[1,2-f][1,2,4]triazin-4-yl) morpholine derivatives as novel PI3K inhibitors

Pyrido-pyrrole triazine compound, and preparation method and application thereof