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Sirico M, D’Angelo A, Gianni C, Casadei C, Merloni F, De Giorgi U. Current State and Future Challenges for PI3K Inhibitors in Cancer Therapy. Cancers (Basel) 2023; 15:703. [PMID: 36765661 PMCID: PMC9913212 DOI: 10.3390/cancers15030703] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 01/16/2023] [Accepted: 01/19/2023] [Indexed: 01/26/2023] Open
Abstract
The phosphoinositide 3 kinase (PI3K)-protein kinase B (PKB/AKT)-mammalian target of the rapamycin (mTOR) axis is a key signal transduction system that links oncogenes and multiple receptor classes which are involved in many essential cellular functions. Aberrant PI3K signalling is one of the most commonly mutated pathways in cancer. Consequently, more than 40 compounds targeting key components of this signalling network have been tested in clinical trials among various types of cancer. As the oncogenic activation of the PI3K/AKT/mTOR pathway often occurs alongside mutations in other signalling networks, combination therapy should be considered. In this review, we highlight recent advances in the knowledge of the PI3K pathway and discuss the current state and future challenges of targeting this pathway in clinical practice.
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Affiliation(s)
- Marianna Sirico
- Department of Medical Oncology, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy
| | - Alberto D’Angelo
- Department of Life Sciences, University of Bath, Bath BA2 7AY, UK
- Department of Oncology, Royal United Hospital, Bath BA1 3NG, UK
| | - Caterina Gianni
- Department of Medical Oncology, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy
| | - Chiara Casadei
- Department of Medical Oncology, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy
| | - Filippo Merloni
- Department of Medical Oncology, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy
| | - Ugo De Giorgi
- Department of Medical Oncology, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy
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2
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Batool A, Aashaq S, Andrabi KI. Eukaryotic initiation factor 4E (eIF4E): A recap of the cap-binding protein. J Cell Biochem 2019; 120:14201-14212. [PMID: 31074051 DOI: 10.1002/jcb.28851] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 12/29/2022]
Abstract
Eukaryotic initiation factor 4E (eIF4E), a fundamental effector and rate limiting element of protein synthesis, binds the 7-methylguanosine cap at the 5' end of eukaryotic messenger RNA (mRNA) specifically as a constituent of eIF4F translation initiation complex thus facilitating the recruitment of mRNA to the ribosomes. This review focusses on the engagement of signals contributing to growth factor originated maxim and their role in the activation of eIF4E to achieve a collective influence on cellular growth, with a key focus on conjuring vital processes like protein synthesis. The review invites considerable interest in elevating the appeal of eIF4E beyond its role in regulating translation viz a viz cancer genesis, attributed to its phosphorylation state that improves the prospect for the growth of the cancerous cell. This review highlights the latest studies that have envisioned to target these pathways and ultimately the translational machinery for therapeutic intervention. The review also brings forward the prospect of eIF4E to act as a converging juncture for signaling pathways like mTOR/PI3K and Mnk/MAPK to promote tumorigenesis.
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Affiliation(s)
- Asiya Batool
- Department of Biotechnology and Bioinformatics, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Sabreena Aashaq
- Department of Biotechnology and Bioinformatics, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Khurshid I Andrabi
- Department of Biotechnology and Bioinformatics, University of Kashmir, Srinagar, Jammu and Kashmir, India
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3
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Abstract
The discovery of small molecules that selectively inhibit Mnks is considered of paramount importance towards deciphering the exact role of these proteins in carcinogenesis and to further validate them as anti-cancer drug targets. However, the dearth of structural information of Mnks is a major hurdle. This study unveils the 7H-pyrrolo[2,3-d]pyrimidine derivatives as potent inhibitors of Mnks. ATP and substrate competition assays showed that this scaffold interacts with the ATP binding site, but not with the substrate site. Screened against a panel of cancer cells, Mnk inhibitors were most potent against MV4-11 acute myeloid leukemia cells. The induction of apoptosis was shown to be mediated by downregulation of Mcl-1.
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4
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Mukhopadhyay S, Frias MA, Chatterjee A, Yellen P, Foster DA. The Enigma of Rapamycin Dosage. Mol Cancer Ther 2016; 15:347-53. [PMID: 26916116 DOI: 10.1158/1535-7163.mct-15-0720] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 11/03/2015] [Indexed: 12/20/2022]
Abstract
The mTOR pathway is a critical regulator of cell growth, proliferation, metabolism, and survival. Dysregulation of mTOR signaling has been observed in most cancers and, thus, the mTOR pathway has been extensively studied for therapeutic intervention. Rapamycin is a natural product that inhibits mTOR with high specificity. However, its efficacy varies by dose in several contexts. First, different doses of rapamycin are needed to suppress mTOR in different cell lines; second, different doses of rapamycin are needed to suppress the phosphorylation of different mTOR substrates; and third, there is a differential sensitivity of the two mTOR complexes mTORC1 and mTORC2 to rapamycin. Intriguingly, the enigmatic properties of rapamycin dosage can be explained in large part by the competition between rapamycin and phosphatidic acid (PA) for mTOR. Rapamycin and PA have opposite effects on mTOR whereby rapamycin destabilizes and PA stabilizes both mTOR complexes. In this review, we discuss the properties of rapamycin dosage in the context of anticancer therapeutics.
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Affiliation(s)
- Suman Mukhopadhyay
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York
| | - Maria A Frias
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York
| | - Amrita Chatterjee
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York
| | - Paige Yellen
- Molecular Pharmacology & Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York
| | - David A Foster
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York. Department of Pharmacology, Weill-Cornell Medical College, New York, New York.
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5
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Li N, Xie C, Lu NH. Transforming growth factor-β: an important mediator in Helicobacter pylori-associated pathogenesis. Front Cell Infect Microbiol 2015; 5:77. [PMID: 26583078 PMCID: PMC4632021 DOI: 10.3389/fcimb.2015.00077] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/20/2015] [Indexed: 12/14/2022] Open
Abstract
Helicobacter pylori (H.pylori) is a Gram-negative, microaerophilic, helical bacillus that specifically colonizes the gastric mucosa. The interaction of virulence factors, host genetic factors, and environmental factors contributes to the pathogenesis of H. pylori-associated conditions, such as atrophic gastritis and intestinal metaplasia. Infection with H. pylori has recently been recognized as the strongest risk factor for gastric cancer. As a pleiotropic cytokine, transforming growth factor (TGF)-β regulates various biological processes, including cell cycle, proliferation, apoptosis, and metastasis. Recent studies have shed new light on the involvement of TGF-β signaling in the pathogenesis of H. pylori infection. This review focuses on the potential etiological roles of TGF-β in H. pylori-mediated gastric pathogenesis.
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Affiliation(s)
- Nianshuang Li
- Department of Gastroenterology, Institute of Digestive Disease, The First Affiliated Hospital of Nanchang University Nanchang, China
| | - Chuan Xie
- Department of Gastroenterology, Institute of Digestive Disease, The First Affiliated Hospital of Nanchang University Nanchang, China
| | - Nong-Hua Lu
- Department of Gastroenterology, Institute of Digestive Disease, The First Affiliated Hospital of Nanchang University Nanchang, China
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6
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Teo T, Lam F, Yu M, Yang Y, Basnet SKC, Albrecht H, Sykes MJ, Wang S. Pharmacologic Inhibition of MNKs in Acute Myeloid Leukemia. Mol Pharmacol 2015; 88:380-9. [DOI: 10.1124/mol.115.098012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 06/04/2015] [Indexed: 01/07/2023] Open
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7
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Sato M, Matsubara T, Adachi J, Hashimoto Y, Fukamizu K, Kishida M, Yang YA, Wakefield LM, Tomonaga T. Differential Proteome Analysis Identifies TGF-β-Related Pro-Metastatic Proteins in a 4T1 Murine Breast Cancer Model. PLoS One 2015; 10:e0126483. [PMID: 25993439 PMCID: PMC4436378 DOI: 10.1371/journal.pone.0126483] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 04/03/2015] [Indexed: 01/04/2023] Open
Abstract
Transforming growth factor-β (TGF-β) has a dual role in tumorigenesis, acting as either a tumor suppressor or as a pro-oncogenic factor in a context-dependent manner. Although TGF-β antagonists have been proposed as anti-metastatic therapies for patients with advanced stage cancer, how TGF-β mediates metastasis-promoting effects is poorly understood. Establishment of TGF-β-related protein expression signatures at the metastatic site could provide new mechanistic information and potentially allow identification of novel biomarkers for clinical intervention to discriminate TGF-β oncogenic effects from tumor suppressive effects. In the present study, we found that systemic administration of the TGF-β receptor kinase inhibitor, SB-431542, significantly inhibited lung metastasis from transplanted 4T1 mammary tumors in Balb/c mice. The differentially expressed proteins in the comparison of lung metastases from SB-431542 treated and control vehicle-treated groups were analyzed by a quantitative LTQ Orbitrap Velos system coupled with stable isotope dimethyl labeling. A total of 36,239 peptides from 6,694 proteins were identified, out of which 4,531 proteins were characterized as differentially expressed. A subset of upregulated proteins in the control group was validated by western blotting and immunohistochemistry. The eukaryotic initiation factor (eIF) family members constituted the most enriched protein pathway in vehicle-treated compared with SB-43512-treated lung metastases, suggesting that increased protein expression of specific eIF family members, especially eIF4A1 and eEF2, is related to the metastatic phenotype of advanced breast cancer and can be down-regulated by TGF-β pathway inhibitors. Thus our proteomic approach identified eIF pathway proteins as novel potential mediators of TGF-β tumor-promoting activity.
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Affiliation(s)
- Misako Sato
- Laboratory of Proteome Research, Proteome Research Center, National Institute of Biomedical Innovation, Saito, Osaka, Japan; Department of Hepatology, Graduate School of Medicine, Osaka City University, Osaka, Japan
| | - Tsutomu Matsubara
- Department of Anatomy and Regenerative Biology, Graduate School of Medicine, Osaka City University, Osaka, Japan
| | - Jun Adachi
- Laboratory of Proteome Research, Proteome Research Center, National Institute of Biomedical Innovation, Saito, Osaka, Japan
| | - Yuuki Hashimoto
- Laboratory of Proteome Research, Proteome Research Center, National Institute of Biomedical Innovation, Saito, Osaka, Japan
| | - Kazuna Fukamizu
- Laboratory of Proteome Research, Proteome Research Center, National Institute of Biomedical Innovation, Saito, Osaka, Japan
| | - Marina Kishida
- Laboratory of Proteome Research, Proteome Research Center, National Institute of Biomedical Innovation, Saito, Osaka, Japan
| | - Yu-An Yang
- Laboratory of Cancer Biology and Genetics, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lalage M Wakefield
- Laboratory of Cancer Biology and Genetics, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Takeshi Tomonaga
- Laboratory of Proteome Research, Proteome Research Center, National Institute of Biomedical Innovation, Saito, Osaka, Japan
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8
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Saqcena M, Patel D, Menon D, Mukhopadhyay S, Foster DA. Apoptotic effects of high-dose rapamycin occur in S-phase of the cell cycle. Cell Cycle 2015; 14:2285-92. [PMID: 25945415 DOI: 10.1080/15384101.2015.1046653] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Mutations in genes encoding regulators of mTOR, the mammalian target of rapamycin, commonly provide survival signals in cancer cells. Rapamycin and analogs of rapamycin have been used with limited success in clinical trials to target mTOR-dependent survival signals in a variety of human cancers. Suppression of mTOR predominantly causes G1 cell cycle arrest, which likely contributes to the ineffectiveness of rapamycin-based therapeutic strategies. While rapamycin causes the accumulation of cells in G1, its effect in other cell cycle phases remains largely unexplored. We report here that when synchronized MDA-MB-231 breast cancer cells are allowed to progress into S-phase from G1, rapamycin activates the apoptotic machinery with a concomitant increase in cell death. In Calu-1 lung cancer cells, rapamycin induced a feedback increase in Akt phosphorylation at Ser473 in S-phase that mitigated rapamycin-induced apoptosis. However, sensitivity to rapamycin in S-phase could be reestablished if Akt phosphorylation was suppressed. We recently reported that glutamine (Gln) deprivation causes K-Ras mutant cancer cells to aberrantly arrest primarily in S-phase. Consistent with observed sensitivity of S-phase cells to rapamycin, interfering with Gln utilization sensitized both MDA-MB-231 and Calu-1 K-Ras mutant cancer cells to the apoptotic effect of rapamycin. Importantly, rapamycin induced substantially higher levels of cell death upon Gln depletion than that observed in cancer cells that were allowed to progress through S-phase after being synchronized in G1. We postulate that exploiting metabolic vulnerabilities in cancer cells such as S-phase arrest observed with K-Ras-driven cancer cells deprived of Gln, could be of great therapeutic potential.
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Key Words
- 4E-BP1, eIF4E binding protein-1
- GOT, glutamate-oxaloacetate-transaminase
- Gln, glutamine
- PARP, poly-ADP-ribose polymerase
- PI3K, phosphatidylinositol-3-kinase
- S6K, S6 kinase
- TGF-β, transforming growth factor-β.
- cell cycle
- eIF4E, eukaryotic initiation factor 4E
- glutamine
- mTOR
- mTOR, mammalian target of rapamycin
- mTORC1/2, mTOR complex 1/2
- rapamycin
- synthetic lethality
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Affiliation(s)
- Mahesh Saqcena
- a Department of Biological Sciences ; Hunter College of the City University of New York ; New York , NY USA
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9
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He K, Zheng X, Li M, Zhang L, Yu J. mTOR inhibitors induce apoptosis in colon cancer cells via CHOP-dependent DR5 induction on 4E-BP1 dephosphorylation. Oncogene 2015; 35:148-57. [PMID: 25867072 PMCID: PMC4603992 DOI: 10.1038/onc.2015.79] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 12/30/2014] [Accepted: 02/05/2015] [Indexed: 12/29/2022]
Abstract
The mammalian target of rapamycin (mTOR) is commonly activated in colon cancer. mTOR complex 1 (mTORC1) is a major downstream target of the PI3K/ATK pathway and activates protein synthesis by phosphorylating key regulators of mRNA translation and ribosome synthesis. Rapamycin analogs Everolimus and Temsirolimus are non-ATP-competitive mTORC1 inhibitors, and suppress proliferation and tumor angiogenesis and invasion. We now show that apoptosis plays a key role in their anti-tumor activities in colon cancer cells and xenografts through the DR5, FADD and caspase-8 axis, and is strongly enhanced by TRAIL and 5-fluorouracil. The induction of DR5 by rapalogs is mediated by the ER stress regulator and transcription factor CHOP, but not the tumor suppressor p53, upon rapid and sustained inhibition of 4E-BP1 phosphorylation, and attenuated by eIF4E expression. ATP-competitive mTOR/PI3K inhibitors also promote DR5 induction and FADD-dependent apoptosis in colon cancer cells. These results establish activation of ER stress and the death receptor pathway as a novel anticancer mechanism of mTOR inhibitors.
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Affiliation(s)
- K He
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | - X Zheng
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | - M Li
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | - L Zhang
- University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA.,Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - J Yu
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
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10
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Chatterjee A, Mukhopadhyay S, Tung K, Patel D, Foster DA. Rapamycin-induced G1 cell cycle arrest employs both TGF-β and Rb pathways. Cancer Lett 2015; 360:134-40. [PMID: 25659819 DOI: 10.1016/j.canlet.2015.01.043] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 01/29/2015] [Accepted: 01/29/2015] [Indexed: 12/11/2022]
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) is a critical regulator of G1 cell cycle progression. Two key substrates of mTORC1 are ribosomal subunit S6 kinase (S6K) and eukaryotic initiation factor 4E (eIF4E) binding protein-1 (4E-BP1). We reported previously that simultaneous knockdown of S6K and eIF4E causes a transforming growth factor-β (TGF-β)-dependent G1 cell cycle arrest in MDA-MB-231 human breast cancer cells. Rapamycin inhibits the phosphorylation of S6K at nano-molar concentrations in MDA-MB-231 cells; however, micro-molar concentrations of rapamycin are required to inhibit phosphorylation of 4E-BP1 - the phosphorylation of which liberates eIF4E to initiate translation. Micro-molar doses of rapamycin are required for complete G1 cell cycle arrest - indicating that 4E-BP1 is a critical target of mTOR for promoting cell cycle progression. Data are provided demonstrating that G1 cell cycle arrest induced by rapamycin is due to up-regulation of TGF-β signaling and down-regulation of Rb phosphorylation via phosphorylation of the mTORC1 substrates S6K and 4E-BP1 respectively. These findings enhance the current understanding of the cytostatic effects of mTORC1 suppression with therapeutic implications.
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Affiliation(s)
- Amrita Chatterjee
- Department of Biological Sciences, Hunter College of the City University of New York, New York, NY, USA
| | - Suman Mukhopadhyay
- Department of Biological Sciences, Hunter College of the City University of New York, New York, NY, USA
| | - Kaity Tung
- Department of Biological Sciences, Hunter College of the City University of New York, New York, NY, USA
| | - Deven Patel
- Department of Biological Sciences, Hunter College of the City University of New York, New York, NY, USA
| | - David A Foster
- Department of Biological Sciences, Hunter College of the City University of New York, New York, NY, USA.
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11
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Mukhopadhyay S, Saqcena M, Chatterjee A, Garcia A, Frias MA, Foster DA. Reciprocal regulation of AMP-activated protein kinase and phospholipase D. J Biol Chem 2015; 290:6986-93. [PMID: 25632961 DOI: 10.1074/jbc.m114.622571] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AMP-activated protein kinase (AMPK), a critical sensor of energy sufficiency, acts as central metabolic switch in cell metabolism. Once activated by low energy status, AMPK phosphorylates key regulatory substrates and turns off anabolic biosynthetic pathways. In contrast, the mammalian/mechanistic target of rapamycin (mTOR) is active when there are sufficient nutrients for anabolic reactions. A critical factor regulating mTOR is phosphatidic acid (PA), a central metabolite of membrane lipid biosynthesis and the product of the phospholipase D (PLD)-catalyzed hydrolysis of phosphatidylcholine. PLD is a downstream target of the GTPase Rheb, which is turned off in response to AMPK via the tuberous sclerosis complex. Although many studies have linked AMPK with mTOR, very little is known about the connection between AMPK and PLD. In this report, we provide evidence for reciprocal regulation of PLD by AMPK and regulation of AMPK by PLD and PA. Suppression of AMPK activity led to an increase in PLD activity, and conversely, activation of AMPK suppressed PLD activity. Suppression of PLD activity resulted in elevated AMPK activity. Exogenously supplied PA abolished the inhibitory effects of elevated AMPK activity on mTOR signaling. In contrast, exogenously supplied PA could not overcome the effect AMPK activation if either mTOR or Raptor was suppressed, indicating that the inhibitory effects of PLD and PA on AMPK activity are mediated by mTOR. These data suggest a reciprocal feedback mechanism involving AMPK and the PLD/mTOR signaling node in cancer cells with therapeutic implications.
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Affiliation(s)
- Suman Mukhopadhyay
- From the Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10065
| | - Mahesh Saqcena
- From the Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10065
| | - Amrita Chatterjee
- From the Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10065
| | - Avalon Garcia
- From the Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10065
| | - Maria A Frias
- From the Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10065
| | - David A Foster
- From the Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10065
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12
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Finotti A, Bianchi N, Fabbri E, Borgatti M, Breveglieri G, Gasparello J, Gambari R. Erythroid induction of K562 cells treated with mithramycin is associated with inhibition of raptor gene transcription and mammalian target of rapamycin complex 1 (mTORC1) functions. Pharmacol Res 2014; 91:57-68. [PMID: 25478892 PMCID: PMC4309890 DOI: 10.1016/j.phrs.2014.11.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 11/21/2014] [Accepted: 11/24/2014] [Indexed: 12/21/2022]
Abstract
Rapamycin, an inhibitor of mTOR activity, is a potent inducer of erythroid differentiation and fetal hemoglobin production in β-thalassemic patients. Mithramycin (MTH) was studied to see if this inducer of K562 differentiation also operates through inhibition of mTOR. We can conclude from the study that the mTOR pathway is among the major transcript classes affected by mithramycin-treatment in K562 cells and a sharp decrease of raptor protein production and p70S6 kinase is detectable in mithramycin treated K562 cells. The promoter sequence of the raptor gene contains several Sp1 binding sites which may explain its mechanism of action. We hypothesize that the G + C-selective DNA-binding drug mithramycin is able to interact with these sequences and to inhibit the binding of Sp1 to the raptor promoter due to the following results: (a) MTH strongly inhibits the interactions between Sp1 and Sp1-binding sites of the raptor promoter (studied by electrophoretic mobility shift assays, EMSA); (b) MTH strongly reduces the recruitment of Sp1 transcription factor to the raptor promoter in intact K562 cells (studied by chromatin immunoprecipitation experiments, ChIP); (c) Sp1 decoy oligonucleotides are able to specifically inhibit raptor mRNA accumulation in K562 cells. In conclusion, raptor gene expression is involved in mithramycin-mediated induction of erythroid differentiation of K562 cells and one of its mechanism of action is the inhibition of Sp1 binding to the raptor promoter.
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Affiliation(s)
- Alessia Finotti
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy
| | - Nicoletta Bianchi
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy
| | - Enrica Fabbri
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy
| | - Monica Borgatti
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy
| | - Giulia Breveglieri
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy
| | - Jessica Gasparello
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy
| | - Roberto Gambari
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, University of Ferrara, Italy.
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13
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Zhang Z, Zheng Y, Zhu R, Zhu Y, Yao W, Liu W, Gao X. The ERK/eIF4F/Bcl-XL pathway mediates SGP-2 induced osteosarcoma cells apoptosis in vitro and in vivo. Cancer Lett 2014; 352:203-13. [DOI: 10.1016/j.canlet.2014.06.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 06/16/2014] [Accepted: 06/24/2014] [Indexed: 11/30/2022]
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14
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Diab S, Kumarasiri M, Yu M, Teo T, Proud C, Milne R, Wang S. MAP kinase-interacting kinases--emerging targets against cancer. ACTA ACUST UNITED AC 2014; 21:441-452. [PMID: 24613018 DOI: 10.1016/j.chembiol.2014.01.011] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 01/28/2014] [Accepted: 01/31/2014] [Indexed: 12/16/2022]
Abstract
Mitogen-activated protein kinase (MAPK)-interacting kinases (Mnks) regulate the initiation of translation through phosphorylation of eukaryotic initiation factor 4E (eIF4E). Mnk-mediated eIF4E activation promotes cancer development and progression. While the phosphorylation of eIF4E is necessary for oncogenic transformation, the kinase activity of Mnks seems dispensable for normal development. For this reason, pharmacological inhibition of Mnks could represent an ideal mechanism-based and nontoxic therapeutic strategy for cancer treatment. In this review, we discuss the current understanding of Mnk biological roles, structures, and functions, as well as clinical implications. Importantly, we propose different strategies for identification of highly selective small molecule inhibitors of Mnks, including exploring a structural feature of their kinase domain, DFD motif, which is unique within the human kinome. We also argue that a combined targeting of Mnks and other pathways should be considered given the complexity of cancer.
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Affiliation(s)
- Sarah Diab
- Centre for Drug Discovery and Development, Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5001, Australia
| | - Malika Kumarasiri
- Centre for Drug Discovery and Development, Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5001, Australia
| | - Mingfeng Yu
- Centre for Drug Discovery and Development, Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5001, Australia
| | - Theodosia Teo
- Centre for Drug Discovery and Development, Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5001, Australia
| | - Christopher Proud
- Centre for Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Robert Milne
- Centre for Drug Discovery and Development, Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5001, Australia
| | - Shudong Wang
- Centre for Drug Discovery and Development, Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5001, Australia.
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15
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Diab S, Teo T, Kumarasiri M, Li P, Yu M, Lam F, Basnet SKC, Sykes MJ, Albrecht H, Milne R, Wang S. Discovery of 5-(2-(Phenylamino)pyrimidin-4-yl)thiazol-2(3H)-one Derivatives as Potent Mnk2 Inhibitors: Synthesis, SAR Analysis and Biological Evaluation. ChemMedChem 2014; 9:962-72. [DOI: 10.1002/cmdc.201300552] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Indexed: 12/24/2022]
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Salloum D, Mukhopadhyay S, Tung K, Polonetskaya A, Foster DA. Mutant ras elevates dependence on serum lipids and creates a synthetic lethality for rapamycin. Mol Cancer Ther 2014; 13:733-41. [PMID: 24435447 DOI: 10.1158/1535-7163.mct-13-0762] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The conversion of normal cells to cancer cells involves a shift from catabolic to anabolic metabolism involving increased glucose uptake and the diversion of glycolytic intermediates into nucleotides, amino acids, and lipids needed for cell growth. An underappreciated aspect of nutrient uptake is the utilization of serum lipids. We investigated the dependence of human cancer cells on serum lipids and report here that Ras-driven human cancer cells are uniquely dependent on serum lipids for both proliferation and survival. Removal of serum lipids also sensitizes Ras-driven cancer cells to rapamycin-indicating that the enhanced need for serum lipids creates a synthetic lethal phenotype that could be exploited therapeutically. Although depriving humans of serum lipids is not practical, suppressing uptake of lipids is possible. Suppressing macropinocytosis in Ras-driven cancer cells also created sensitivity to suppression of the mammalian/mechanistic target of rapamycin complex 1 (mTORC1). It is speculated that this property displayed by Ras-driven cancer cells represents an Achilles' heel for the large number of human cancers that are driven by activating Ras mutations.
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Affiliation(s)
- Darin Salloum
- Corresponding Author: David A. Foster, Department of Biological Sciences, Hunter College of the City University of New York, 695 Park Avenue, New York, NY 10065.
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