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Jhanwar-Uniyal M, Zeller SL, Spirollari E, Das M, Hanft SJ, Gandhi CD. Discrete Mechanistic Target of Rapamycin Signaling Pathways, Stem Cells, and Therapeutic Targets. Cells 2024; 13:409. [PMID: 38474373 DOI: 10.3390/cells13050409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 02/14/2024] [Accepted: 02/22/2024] [Indexed: 03/14/2024] Open
Abstract
The mechanistic target of rapamycin (mTOR) is a serine/threonine kinase that functions via its discrete binding partners to form two multiprotein complexes, mTOR complex 1 and 2 (mTORC1 and mTORC2). Rapamycin-sensitive mTORC1, which regulates protein synthesis and cell growth, is tightly controlled by PI3K/Akt and is nutrient-/growth factor-sensitive. In the brain, mTORC1 is also sensitive to neurotransmitter signaling. mTORC2, which is modulated by growth factor signaling, is associated with ribosomes and is insensitive to rapamycin. mTOR regulates stem cell and cancer stem cell characteristics. Aberrant Akt/mTOR activation is involved in multistep tumorigenesis in a variety of cancers, thereby suggesting that the inhibition of mTOR may have therapeutic potential. Rapamycin and its analogues, known as rapalogues, suppress mTOR activity through an allosteric mechanism that only suppresses mTORC1, albeit incompletely. ATP-catalytic binding site inhibitors are designed to inhibit both complexes. This review describes the regulation of mTOR and the targeting of its complexes in the treatment of cancers, such as glioblastoma, and their stem cells.
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Affiliation(s)
- Meena Jhanwar-Uniyal
- Department of Neurosurgery, Westchester Medical Center, New York Medical College, Valhalla, NY 10595, USA
| | - Sabrina L Zeller
- Department of Neurosurgery, Westchester Medical Center, New York Medical College, Valhalla, NY 10595, USA
| | - Eris Spirollari
- Department of Neurosurgery, Westchester Medical Center, New York Medical College, Valhalla, NY 10595, USA
| | - Mohan Das
- Department of Neurosurgery, Westchester Medical Center, New York Medical College, Valhalla, NY 10595, USA
| | - Simon J Hanft
- Department of Neurosurgery, Westchester Medical Center, New York Medical College, Valhalla, NY 10595, USA
| | - Chirag D Gandhi
- Department of Neurosurgery, Westchester Medical Center, New York Medical College, Valhalla, NY 10595, USA
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Cuellar-Vite L, Weber-Bonk KL, Abdul-Karim FW, Booth CN, Keri RA. Focal Adhesion Kinase Provides a Collateral Vulnerability That Can Be Leveraged to Improve mTORC1 Inhibitor Efficacy. Cancers (Basel) 2022; 14:3374. [PMID: 35884439 PMCID: PMC9323520 DOI: 10.3390/cancers14143374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/01/2022] [Accepted: 07/06/2022] [Indexed: 11/16/2022] Open
Abstract
The PI3K/AKT/mTORC1 pathway is a major therapeutic target for many cancers, particularly breast cancer. Everolimus is an mTORC1 inhibitor used in metastatic estrogen receptor-positive (ER+) and epidermal growth factor receptor 2-negative (HER2-) breast cancer. However, mTORC1 inhibitors have limited efficacy in other breast cancer subtypes. We sought to discover collateral sensitivities to mTORC1 inhibition that could be exploited to improve therapeutic response. Using a mouse model of breast cancer that is intrinsically resistant to mTORC1 inhibition, we found that rapamycin alters the expression of numerous extracellular matrix genes, suggesting a potential role for integrins/FAK in controlling mTORC1-inhibitor efficacy. FAK activation was also inversely correlated with rapamycin response in breast cancer cell lines. Supporting its potential utility in patients, FAK activation was observed in >50% of human breast cancers. While blocking FAK in mouse models of breast cancer that are highly responsive to rapamycin had no impact on tumor growth, FAK inhibition sensitized rapamycin-resistant tumors to mTORC1 inhibition. These data reveal an innate dependency on FAK when mTORC1 signaling is lost in tumors that are resistant to mTORC1 inhibitors. They also suggest a precision medicine approach to improving mTORC1 inhibitor efficacy in resistant cancers by suppressing FAK signaling.
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Affiliation(s)
- Leslie Cuellar-Vite
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA;
- Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA;
| | - Kristen L. Weber-Bonk
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA;
| | - Fadi W. Abdul-Karim
- Anatomic Pathology, Pathology & Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (F.W.A.-K.); (C.N.B.)
| | - Christine N. Booth
- Anatomic Pathology, Pathology & Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (F.W.A.-K.); (C.N.B.)
| | - Ruth A. Keri
- Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA;
- Department of General Medical Sciences-Oncology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
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3
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Hu X, Ma Z, Wen L, Li S, Dong Z. Autophagy in Cisplatin Nephrotoxicity during Cancer Therapy. Cancers (Basel) 2021; 13:5618. [PMID: 34830772 PMCID: PMC8616020 DOI: 10.3390/cancers13225618] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/23/2021] [Accepted: 11/04/2021] [Indexed: 12/12/2022] Open
Abstract
Cisplatin is a widely used chemotherapeutic agent but its clinical use is often limited by nephrotoxicity. Autophagy is a lysosomal degradation pathway that removes protein aggregates and damaged or dysfunctional cellular organelles for maintaining cell homeostasis. Upon cisplatin exposure, autophagy is rapidly activated in renal tubule cells to protect against acute cisplatin nephrotoxicity. Mechanistically, the protective effect is mainly related to the clearance of damaged mitochondria via mitophagy. The role and regulation of autophagy in chronic kidney problems after cisplatin treatment are currently unclear, despite the significance of research in this area. In cancers, autophagy may prevent tumorigenesis, but autophagy may reduce the efficacy of chemotherapy by protecting cancer cells. Future research should focus on developing drugs that enhance the anti-tumor effects of cisplatin while protecting kidneys during cisplatin chemotherapy.
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Affiliation(s)
- Xiaoru Hu
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha 410011, China; (X.H.); (L.W.); (S.L.)
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA;
- Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
| | - Zhengwei Ma
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA;
- Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
| | - Lu Wen
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha 410011, China; (X.H.); (L.W.); (S.L.)
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA;
- Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
| | - Siyao Li
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha 410011, China; (X.H.); (L.W.); (S.L.)
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA;
- Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
| | - Zheng Dong
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha 410011, China; (X.H.); (L.W.); (S.L.)
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA;
- Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
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4
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Xiao B, Zuo D, Hirukawa A, Cardiff RD, Lamb R, Sonenberg N, Muller WJ. Rheb1-Independent Activation of mTORC1 in Mammary Tumors Occurs through Activating Mutations in mTOR. Cell Rep 2021; 31:107571. [PMID: 32348753 DOI: 10.1016/j.celrep.2020.107571] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 12/06/2019] [Accepted: 04/02/2020] [Indexed: 11/25/2022] Open
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) is a master modulator of cellular growth, and its aberrant regulation is recurrently documented within breast cancer. While the small GTPase Rheb1 is the canonical activator of mTORC1, Rheb1-independent mechanisms of mTORC1 activation have also been reported but have not been fully understood. Employing multiple transgenic mouse models of breast cancer, we report that ablation of Rheb1 significantly impedes mammary tumorigenesis. In the absence of Rheb1, a block in tumor initiation can be overcome by multiple independent mutations in Mtor to allow Rheb1-independent reactivation of mTORC1. We further demonstrate that the mTOR kinase is indispensable for tumor initiation as the genetic ablation of mTOR abolishes mammary tumorigenesis. Collectively, our findings demonstrate that mTORC1 activation is indispensable for mammary tumor initiation and that tumors acquire alternative mechanisms of mTORC1 activation.
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Affiliation(s)
- Bin Xiao
- Department of Biochemistry, McGill University, Montreal, QC H3A 1A3, Canada; Rosalind & Morris Goodman Cancer Centre, McGill University, Montreal, QC H3A 1A3, Canada
| | - Dongmei Zuo
- Department of Biochemistry, McGill University, Montreal, QC H3A 1A3, Canada; Rosalind & Morris Goodman Cancer Centre, McGill University, Montreal, QC H3A 1A3, Canada
| | - Alison Hirukawa
- Department of Biochemistry, McGill University, Montreal, QC H3A 1A3, Canada; Rosalind & Morris Goodman Cancer Centre, McGill University, Montreal, QC H3A 1A3, Canada
| | - Robert D Cardiff
- Center for Comparative Medicine, University of California, Davis, Davis, CA 95616, USA
| | | | - Nahum Sonenberg
- Department of Biochemistry, McGill University, Montreal, QC H3A 1A3, Canada; Faculty of Medicine, McGill University, Montreal, QC H3A 1A3, Canada; Rosalind & Morris Goodman Cancer Centre, McGill University, Montreal, QC H3A 1A3, Canada
| | - William J Muller
- Department of Biochemistry, McGill University, Montreal, QC H3A 1A3, Canada; Faculty of Medicine, McGill University, Montreal, QC H3A 1A3, Canada; Rosalind & Morris Goodman Cancer Centre, McGill University, Montreal, QC H3A 1A3, Canada.
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5
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Nandi U, Onyesom I, Douroumis D. An in vitro evaluation of antitumor activity of sirolimus-encapsulated liposomes in breast cancer cells. J Pharm Pharmacol 2021; 73:300-309. [PMID: 33793879 DOI: 10.1093/jpp/rgaa061] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 12/28/2020] [Indexed: 01/06/2023]
Abstract
OBJECTIVES Design and examine the effect of sirolimus-PEGylated (Stealth) liposomes for breast cancer treatment. In this study, we developed conventional and Stealth liposome nanoparticles comprising of distearoylphosphatidylcholine (DSPC) or dipalmitoyl-phosphatidylcholine (DPPC) and DSPE-MPEG-2000 lipids loaded with sirolimus as an anticancer agent. The effect of lipid grade, drug loading and incubation times were evaluated. METHODS Particle size distribution, encapsulation efficiency of conventional and Stealth liposomes were studied followed by cytotoxicity evaluation. The cellular uptake and internal localisation of liposome formulations were investigated using confocal microscopy. KEY FINDINGS The designed Stealth liposome formulations loaded with sirolimus demonstrated an effective in vitro anticancer therapy compared with conventional liposomes while the length of the acyl chain affected the cell viability. Anticancer activity was found to be related on the drug loading amounts and incubation times. Cell internalization was observed after 5 h while significant cellular uptake of liposome was detected after 24 h with liposome particles been located in the cytoplasm round the cell nucleus. Sirolimus Stealth liposomes induced cell apoptosis. CONCLUSIONS The design and evaluation of sirolimus-loaded PEGylated liposome nanoparticles demonstrated their capacity as drug delivery carrier for the treatment of breast cancer tumours.
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Affiliation(s)
- Uttom Nandi
- Medway School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent, UK
| | - Ichioma Onyesom
- Medway School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent, UK
| | - Dennis Douroumis
- Medway School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent, UK
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6
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Zervantonakis IK, Poskus MD, Scott AL, Selfors LM, Lin JR, Dillon DA, Pathania S, Sorger PK, Mills GB, Brugge JS. Fibroblast-tumor cell signaling limits HER2 kinase therapy response via activation of MTOR and antiapoptotic pathways. Proc Natl Acad Sci U S A 2020; 117:16500-16508. [PMID: 32601199 PMCID: PMC7368275 DOI: 10.1073/pnas.2000648117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Despite the implementation of multiple HER2-targeted therapies, patients with advanced HER2+ breast cancer ultimately develop drug resistance. Stromal fibroblasts represent an abundant cell type in the tumor microenvironment and have been linked to poor outcomes and drug resistance. Here, we show that fibroblasts counteract the cytotoxic effects of HER2 kinase-targeted therapy in a subset of HER2+ breast cancer cell lines and allow cancer cells to proliferate in the presence of the HER2 kinase inhibitor lapatinib. Fibroblasts from primary breast tumors, normal breast tissue, and lung tissue have similar protective effects on tumor cells via paracrine factors. This fibroblast-mediated reduction in drug sensitivity involves increased expression of antiapoptotic proteins and sustained activation of the PI3K/AKT/MTOR pathway, despite inhibition of the HER2 and the RAS-ERK pathways in tumor cells. HER2 therapy sensitivity is restored in the fibroblast cocultures by combination treatment with inhibitors of MTOR or the antiapoptotic proteins BCL-XL and MCL-1. Expression of activated AKT in tumor cells recapitulates the effects of fibroblasts resulting in sustained MTOR signaling and poor lapatinib response. Lapatinib sensitivity was not altered by fibroblasts in tumor cells that exhibited sustained MTOR signaling due to a strong gain-of-function PI3KCA mutation. These findings indicate that in addition to tumor cell-intrinsic mechanisms that cause constitutive PI3K/AKT/MTOR pathway activation, secreted factors from fibroblasts can maintain this pathway in the context of HER2 inhibition. Our integrated proteomic-phenotypic approach presents a strategy for the discovery of protective mechanisms in fibroblast-rich tumors and the design of rational combination therapies to restore drug sensitivity.
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Affiliation(s)
- Ioannis K Zervantonakis
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15213;
- UPMC Hillman Cancer Center, University of Pittsburgh Medical Center, Pittsburgh, PA 15232
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Matthew D Poskus
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15213
| | - Alexis L Scott
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15213
| | - Laura M Selfors
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Jia-Ren Lin
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Deborah A Dillon
- Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115
| | - Shailja Pathania
- Center for Personalized Cancer Therapy, University of Massachusetts Boston, Boston, MA 02125
| | - Peter K Sorger
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Gordon B Mills
- Knight Cancer Institute, Oregon Health and Sciences University, Portland, OR 97239
| | - Joan S Brugge
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115;
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7
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Csiszar A, Balasubramanian P, Tarantini S, Yabluchanskiy A, Zhang XA, Springo Z, Benbrook D, Sonntag WE, Ungvari Z. Chemically induced carcinogenesis in rodent models of aging: assessing organismal resilience to genotoxic stressors in geroscience research. GeroScience 2019; 41:209-227. [PMID: 31037472 DOI: 10.1007/s11357-019-00064-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 04/04/2019] [Indexed: 02/07/2023] Open
Abstract
There is significant overlap between the cellular and molecular mechanisms of aging and pathways contributing to carcinogenesis, including the role of genome maintenance pathways. In the field of geroscience analysis of novel genetic mouse models with either a shortened, or an extended, lifespan provides a unique opportunity to evaluate the synergistic roles of longevity assurance pathways in cancer resistance and regulation of lifespan and to develop novel targets for interventions that both delay aging and prevent carcinogenesis. There is a growing need for robust assays to assess the susceptibility of cancer in these models. The present review focuses on a well-characterized method frequently used in cancer research, which can be adapted to study resilience to genotoxic stress and susceptibility to genotoxic stress-induced carcinogenesis in geroscience research namely, chemical carcinogenesis induced by treatment with 7,12-dimethylbenz(a)anthracene (DMBA). Recent progress in understanding how longer-living mice may achieve resistance to chemical carcinogenesis and how these pathways are modulated by anti-aging interventions is reviewed. Strain-specific differences in sensitivity to DMBA-induced carcinogenesis are also explored and contrasted with mouse lifespan. The clinical relevance of inhibition of DMBA-induced carcinogenesis for the pathogenesis of mammary adenocarcinomas in older human subjects is discussed. Finally, the potential role of insulin-like growth factor-1 (IGF-1) in the regulation of pathways responsible for cellular resilience to DMBA-induced mutagenesis is discussed.
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Affiliation(s)
- Anna Csiszar
- Department of Geriatric Medicine Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA.,Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Priya Balasubramanian
- Department of Geriatric Medicine Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
| | - Stefano Tarantini
- Department of Geriatric Medicine Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
| | - Andriy Yabluchanskiy
- Department of Geriatric Medicine Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA.,Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Xin A Zhang
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Zsolt Springo
- Department of Geriatric Medicine Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA.,Theoretical Medicine Doctoral School, University of Szeged, Szeged, Hungary
| | - Doris Benbrook
- Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.,Department of Obstetrics and Gynecology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - William E Sonntag
- Department of Geriatric Medicine Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA.,Department of Biochemistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Zoltan Ungvari
- Department of Geriatric Medicine Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA. .,Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA. .,Theoretical Medicine Doctoral School, University of Szeged, Szeged, Hungary. .,Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary. .,Department of Public Health, Semmelweis University, Budapest, Hungary.
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8
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Fan DX, Yang XH, Li YN, Guo L. 17β-Estradiol on the Expression of G-Protein Coupled Estrogen Receptor (GPER/GPR30) Mitophagy, and the PI3K/Akt Signaling Pathway in ATDC5 Chondrocytes In Vitro. Med Sci Monit 2018; 24:1936-1947. [PMID: 29608013 PMCID: PMC5898603 DOI: 10.12659/msm.909365] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Background Osteoarthritis is a progressive inflammatory joint disease resulting in damage to articular cartilage. G-protein coupled estrogen receptor (GPER/GPR30) activates cell signaling in response to 17β-estradiol, which can be blocked by the GPR30 agonist, G15, an analog of G-1. The aims of this study were to investigate the effects of 17β-estradiol on the expression of G-protein coupled estrogen receptor (GPER/GPR30) on mitophagy and the PI3K/Akt signaling pathway in ATDC5 chondrocytes in vitro. Material/Methods Cultured ATDC5 chondrocytes were treated with increasing concentrations of 17β-estradiol with and without G15, p38 inhibitor (SB203580), JNK inhibitor (SP600125), PI3K inhibitor (LY294002, S1737), and mTOR inhibitor (S1842). Expression of GPER/GPR30 and components of the PI3K/Akt pathway in cultured ATDC5 chondrocytes were detected by immunofluorescence (IF) staining, Western blot, and real-time polymerase chain reaction (RT-PCR). Transmission electron microscopy (TEM) and IF were used to detect mitophagosomes. Expression of LC-3, LAMP2, TOM20, Hsp60, p-Akt, p-mTOR, p-p38, and p-JNK was investigated by Western blot. Proliferation and viability of the ATDC5 chondrocytes were determined using BrdU and MTT assays. Results In 17β-estradiol-treated ATDC5 chondrocytes, increased expression of GPER/GPR30 was found, but fewer mitophagosomes were observed, and decreased numbers of TOM20-positive granules were co-localized with decreased LAMP2 and increased expression levels of TOM20, Hsp60, p-Akt, and p-mTOR, and reduced expression of LC3-II, were found. In 17β-estradiol-treated ATDC5 chondrocytes, the proliferation and viability of the 17β-estradiol-treated ATDC5 chondrocytes were significantly elevated. Conclusions Treatment with 17β-estradiol protected ATDC5 chondrocytes against mitophagy via the GPER/GPR30 and the PI3K/Akt signaling pathway.
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Affiliation(s)
- Dong-Xiao Fan
- Department of Orthopedic Surgery, First Affiliated Hospital, China Medical University, Shenyang, Liaoning, China (mainland).,Orthopedic Surgery, First Affiliated Hospital, China Medical University, , China (mainland)
| | - Xu-Hao Yang
- Department of Orthopedic Surgery, First Affiliated Hospital, China Medical University, Shenyang, Liaoning, China (mainland)
| | - Yi-Nan Li
- Department of Orthopedic Surgery, First Affiliated Hospital, China Medical University, Shenyang, Liaoning, China (mainland)
| | - Lei Guo
- Department of Orthopedic Surgery, First Affiliated Hospital, China Medical University, Shenyang, Liaoning, China (mainland)
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Evolving Significance and Future Relevance of Anti-Angiogenic Activity of mTOR Inhibitors in Cancer Therapy. Cancers (Basel) 2017; 9:cancers9110152. [PMID: 29104248 PMCID: PMC5704170 DOI: 10.3390/cancers9110152] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 10/23/2017] [Accepted: 10/27/2017] [Indexed: 12/12/2022] Open
Abstract
mTOR inhibitors have demonstrated remarkable anti-tumor activity in experimental models, mainly by reducing cancer cell growth and tumor angiogenesis. Their use in cancer patients as monotherapy has, however, generated only limited benefits, increasing median overall survival by only a few months. Likewise, in other targeted therapies, cancer cells develop resistance mechanisms to overcome mTOR inhibition. Hence, novel therapeutic strategies have to be designed to increase the efficacy of mTOR inhibitors in cancer. In this review, we discuss the present and future relevance of mTOR inhibitors in cancer therapy by focusing on their effects on tumor angiogenesis.
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10
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Yori JL, Lozada KL, Seachrist DD, Mosley JD, Abdul-Karim FW, Booth CN, Flask CA, Keri RA. Combined SFK/mTOR inhibition prevents rapamycin-induced feedback activation of AKT and elicits efficient tumor regression. Cancer Res 2014; 74:4762-71. [PMID: 25023728 DOI: 10.1158/0008-5472.can-13-3627] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Resistance to receptor tyrosine kinase (RTK) blockade in breast cancer is often mediated by activation of bypass pathways that sustain growth. Src and mammalian target of rapamycin (mTOR) are two intrinsic targets that are downstream of most RTKs. To date, limited clinical efficacy has been observed with either Src or mTOR inhibitors when used as single agents. Resistance to mTOR inhibitors is associated with loss of negative feedback regulation, resulting in phosphorylation and activation of AKT. Herein, we describe a novel role for Src in contributing to rapalog-induced AKT activation. We found that dual activation of Src and the mTOR pathway occurs in nearly half of all breast cancers, suggesting potential cross-talk. As expected, rapamycin inhibition of mTOR results in feedback activation of AKT in breast cancer cell lines. Addition of the Src/c-Abl inhibitor, dasatinib, completely blocks this feedback activation, confirming convergence between Src and the mTOR pathway. Analysis in vivo revealed that dual Src and mTOR inhibition is highly effective in two mouse models of breast cancer. In a luminal disease model, combined dasatinib and rapamycin is more effective at inducing regression than either single agent. Furthermore, the combination of dasatinib and rapamycin delays tumor recurrence following the cessation of treatment. In a model of human EGFR-2-positive (HER2(+)) disease, dasatinib alone is ineffective, but potentiates the efficacy of rapamycin. These data suggest that combining mTOR and Src inhibitors may provide a new approach for treating multiple breast cancer subtypes that may circumvent resistance to targeted RTK therapies.
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Affiliation(s)
- Jennifer L Yori
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio
| | - Kristen L Lozada
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio
| | - Darcie D Seachrist
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio
| | - Jonathan D Mosley
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Fadi W Abdul-Karim
- Department of Anatomic Pathology, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Christine N Booth
- Department of Anatomic Pathology, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Chris A Flask
- Department of Radiology, Case Western Reserve University, School of Medicine, Cleveland, Ohio. Department of Biomedical Engineering, Case Western Reserve University, School of Medicine, Cleveland, Ohio. Department of Pediatrics, Case Western Reserve University, School of Medicine, Cleveland, Ohio
| | - Ruth A Keri
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio. Department of Genetics and Division of General Medical Sciences-Oncology, Case Western Reserve University, School of Medicine, Cleveland, Ohio.
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11
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Yan C, Wei H, Minjuan Z, Yan X, Jingyue Y, Wenchao L, Sheng H. The mTOR inhibitor rapamycin synergizes with a fatty acid synthase inhibitor to induce cytotoxicity in ER/HER2-positive breast cancer cells. PLoS One 2014; 9:e97697. [PMID: 24866893 PMCID: PMC4035285 DOI: 10.1371/journal.pone.0097697] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 04/23/2014] [Indexed: 12/20/2022] Open
Abstract
Patients with ER/HER2-positive breast cancer have a poor prognosis and are less responsive to selective estrogen receptor modulators; this is presumably due to the crosstalk between ER and HER2. Fatty acid synthase (FASN) is essential for the survival and maintenance of the malignant phenotype of breast cancer cells. An intimate relationship exists between FASN, ER and HER2. We hypothesized that FASN may be the downstream effector underlying ER/HER2 crosstalk through the PI3K/AKT/mTOR pathway in ER/HER2-positive breast cancer. The present study implicated the PI3K/AKT/mTOR pathway in the regulation of FASN expression in ER/HER2-positive breast cancer cells and demonstrated that rapamycin, an mTOR inhibitor, inhibited FASN expression. Cerulenin, a FASN inhibitor, synergized with rapamycin to induce apoptosis and inhibit cell migration and tumorigenesis in ER/HER2-positive breast cancer cells. Our findings suggest that inhibiting the mTOR-FASN axis is a promising new strategy for treating ER/HER2-positive breast cancer.
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MESH Headings
- Animals
- Apoptosis/drug effects
- Blotting, Western
- Breast Neoplasms/drug therapy
- Breast Neoplasms/enzymology
- Breast Neoplasms/pathology
- Cell Movement/drug effects
- Cell Proliferation/drug effects
- Cerulenin/pharmacology
- Drug Synergism
- Estrogen Receptor alpha/genetics
- Estrogen Receptor alpha/metabolism
- Fatty Acid Synthase, Type I/antagonists & inhibitors
- Fatty Acid Synthase, Type I/genetics
- Fatty Acid Synthase, Type I/metabolism
- Female
- Fluorescent Antibody Technique, Indirect
- Gene Expression Regulation, Neoplastic/drug effects
- Humans
- Mice
- Mice, Nude
- Protein Kinase Inhibitors/pharmacology
- RNA, Messenger/genetics
- Real-Time Polymerase Chain Reaction
- Receptor, ErbB-2/genetics
- Receptor, ErbB-2/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sirolimus/pharmacology
- Tumor Cells, Cultured
- Xenograft Model Antitumor Assays
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Affiliation(s)
- Chen Yan
- Department of Oncology, Xi'jing Hospital, Fourth Military Medical University, Xi'an, PR China
| | - Huang Wei
- Department of Cardiology, Xi'jing hospital, Fourth military medical university, Xi'an, PR China
| | - Zheng Minjuan
- Department of Ultrasound, Xi'jing Hospital, Fourth Military Medical University, Xi'an, PR China
| | - Xue Yan
- Department of Oncology, Xi'jing Hospital, Fourth Military Medical University, Xi'an, PR China
| | - Yang Jingyue
- Department of Oncology, Xi'jing Hospital, Fourth Military Medical University, Xi'an, PR China
| | - Liu Wenchao
- Department of Oncology, Xi'jing Hospital, Fourth Military Medical University, Xi'an, PR China
- * E-mail: (LW); (HS)
| | - Han Sheng
- State Key Laboratory of Military Stomatology, Department of Information Center, School of Stomatology, Fourth Military Medical University, Xi'an, PR China
- * E-mail: (LW); (HS)
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12
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SIRT6: a promising target for cancer prevention and therapy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 818:181-96. [PMID: 25001537 DOI: 10.1007/978-1-4471-6458-6_9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Many of the pathologies associated with the aging process also contribute to tumor initiation, growth or metastasis. Insights from biogerontology may be instrumental for developing new therapies for cancer. This chapter highlights the rationale for combining biogerontology and cancer research to generate new strategies for cancer treatment. In particular, this chapter focuses on one gene, SIRT6, which has emerged as an important regulator of longevity in mammals and appears to have multiple biochemical functions, which antagonize tumor development and may be useful in cancer prevention and treatment.
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13
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Guilbert C, Annis MG, Dong Z, Siegel PM, Miller WH, Mann KK. Arsenic trioxide overcomes rapamycin-induced feedback activation of AKT and ERK signaling to enhance the anti-tumor effects in breast cancer. PLoS One 2013; 8:e85995. [PMID: 24392034 PMCID: PMC3877392 DOI: 10.1371/journal.pone.0085995] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 12/03/2013] [Indexed: 11/18/2022] Open
Abstract
Inhibitors of the mammalian target of rapamycin (mTORi) have clinical activity; however, the benefits of mTOR inhibition by rapamycin and rapamycin-derivatives (rapalogs) may be limited by a feedback mechanism that results in AKT activation. Increased AKT activity resulting from mTOR inhibition can be a result of increased signaling via the mTOR complex, TORC2. Previously, we published that arsenic trioxide (ATO) inhibits AKT activity and in some cases, decreases AKT protein expression. Therefore, we propose that combining ATO and rapamycin may circumvent the AKT feedback loop and increase the anti-tumor effects. Using a panel of breast cancer cell lines, we find that ATO, at clinically-achievable doses, can enhance the inhibitory activity of the mTORi temsirolimus. In all cell lines, temsirolimus treatment resulted in AKT activation, which was decreased by concomitant ATO treatment only in those cell lines where ATO enhanced growth inhibition. Treatment with rapalog also results in activated ERK signaling, which is decreased with ATO co-treatment in all cell lines tested. We next tested the toxicity and efficacy of rapamycin plus ATO combination therapy in a MDA-MB-468 breast cancer xenograft model. The drug combination was well-tolerated, and rapamycin did not increase ATO-induced liver enzyme levels. In addition, combination of these drugs was significantly more effective at inhibiting tumor growth compared to individual drug treatments, which corresponded with diminished phospho-Akt and phospho-ERK levels when compared with rapamycin-treated tumors. Therefore, we propose that combining ATO and mTORi may overcome the feedback loop by decreasing activation of the MAPK and AKT signaling pathways.
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Affiliation(s)
- Cynthia Guilbert
- Lady Davis Institute for Medical Research, McGill University, Montreal, Canada
| | - Matthew G. Annis
- Rosalind and Morris Goodman Cancer Research Centre, McGill University, Montreal, Canada
| | - Zhifeng Dong
- Rosalind and Morris Goodman Cancer Research Centre, McGill University, Montreal, Canada
| | - Peter M. Siegel
- Rosalind and Morris Goodman Cancer Research Centre, McGill University, Montreal, Canada
| | - Wilson H. Miller
- Lady Davis Institute for Medical Research, McGill University, Montreal, Canada
- Department of Oncology, McGill University, Montreal, Canada
| | - Koren K. Mann
- Lady Davis Institute for Medical Research, McGill University, Montreal, Canada
- Department of Oncology, McGill University, Montreal, Canada
- * E-mail:
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14
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Abstract
Recent groundbreaking discoveries have revealed that IGF-1, Ras, MEK, AMPK, TSC1/2, FOXO, PI3K, mTOR, S6K, and NFκB are involved in the aging process. This is remarkable because the same signaling molecules, oncoproteins and tumor suppressors, are well-known targets for cancer therapy. Furthermore, anti-cancer drugs aimed at some of these targets have been already developed. This arsenal could be potentially employed for anti-aging interventions (given that similar signaling molecules are involved in both cancer and aging). In cancer, intrinsic and acquired resistance, tumor heterogeneity, adaptation, and genetic instability of cancer cells all hinder cancer-directed therapy. But for anti-aging applications, these hurdles are irrelevant. For example, since anti-aging interventions should be aimed at normal postmitotic cells, no selection for resistance is expected. At low doses, certain agents may decelerate aging and age-related diseases. Importantly, deceleration of aging can in turn postpone cancer, which is an age-related disease.
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15
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Blagosklonny MV. Common drugs and treatments for cancer and age-related diseases: revitalizing answers to NCI's provocative questions. Oncotarget 2013; 3:1711-24. [PMID: 23565531 PMCID: PMC3681506 DOI: 10.18632/oncotarget.890] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In 2011, The National Cancer Institute (NCI) has announced 24 provocative questions on cancer. Some of these questions have been already answered in “NCI's provocative questions on cancer: some answers to ignite discussion” (published in Oncotarget, 2011, 2: 1352.) The questions included “Why do many cancer cells die when suddenly deprived of a protein encoded by an oncogene?” “Can we extend patient survival by using approaches that keep tumors static?” “Why are some disseminated cancers cured by chemotherapy alone?” “Can we develop methods to rapidly test interventions for cancer treatment or prevention?” “Can we use our knowledge of aging to enhance prevention or treatment of cancer?” “What is the mechanism by which some drugs commonly and chronically used for other indications protect against cancer?” “How does obesity contribute to cancer risk?” I devoted a single subchapter to each the answer. As expected, the provocative questions were very diverse and numerous. Now I choose and combine, as a single problem, only three last questions, all related to common mechanisms and treatment of age-related diseases including obesity and cancer. Can we use common existing drugs for cancer prevention and treatment? Can we use some targeted “cancer-selective” agents for other diseases and … aging itself.
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Affiliation(s)
- Mikhail V Blagosklonny
- Department of Cell Stress Biology, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY, USA.
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16
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Hurvitz SA, Hu Y, O'Brien N, Finn RS. Current approaches and future directions in the treatment of HER2-positive breast cancer. Cancer Treat Rev 2013; 39:219-29. [PMID: 22658319 PMCID: PMC3835685 DOI: 10.1016/j.ctrv.2012.04.008] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 04/17/2012] [Accepted: 04/26/2012] [Indexed: 01/03/2023]
Abstract
Human epidermal growth factor receptor 2 (HER2), a member of the ErbB family of transmembrane receptor tyrosine kinases, is amplified in 20-30% of invasive breast cancers. HER2 amplification is associated with metastasis and reduced survival. Two HER2-directed therapies have been approved by the United States Food and Drug Administration for the treatment of HER2-overexpressing breast cancer: trastuzumab, a humanized monoclonal antibody against the extracellular portion of HER2; and lapatinib, a dual HER2- and epidermal growth factor receptor-specific tyrosine kinase inhibitor. Despite the improvement in overall survival with the addition of HER2-targeted agents to chemotherapy, many patients do not benefit from these agents because of inherent resistance. In addition, many patients who achieve an initial response eventually acquire drug resistance. Currently, several mechanisms of resistance have been described, including mutations in other signaling pathways, expression of a truncated form of HER2, receptor crosstalk, and autophagy. There are several approaches under study to target these pathways of resistance, including blocking PI3 kinase and mammalian target of rapamycin signaling, blocking neoangiogenesis and the vascular endothelial growth factor axis, using monoclonal antibody targeting of the HER2 dimerization site, and using HER2 monoclonal antibody-drug conjugates. Here we will review the current scientific rationale for these agents and how combinations of these agents may yield additive or synergistic effects and lead to improved outcomes for patients with HER2-amplified breast cancer.
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Affiliation(s)
- Sara A Hurvitz
- University of California at Los Angeles, Los Angeles, CA 90095, USA.
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17
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Korsse SE, Peppelenbosch MP, van Veelen W. Targeting LKB1 signaling in cancer. Biochim Biophys Acta Rev Cancer 2012; 1835:194-210. [PMID: 23287572 DOI: 10.1016/j.bbcan.2012.12.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 12/18/2012] [Accepted: 12/20/2012] [Indexed: 12/13/2022]
Abstract
The serine/threonine kinase LKB1 is a master kinase involved in cellular responses such as energy metabolism, cell polarity and cell growth. LKB1 regulates these crucial cellular responses mainly via AMPK/mTOR signaling. Germ-line mutations in LKB1 are associated with the predisposition of the Peutz-Jeghers syndrome in which patients develop gastrointestinal hamartomas and have an enormously increased risk for developing gastrointestinal, breast and gynecological cancers. In addition, somatic inactivation of LKB1 has been associated with sporadic cancers such as lung cancer. The exact mechanisms of LKB1-mediated tumor suppression remain so far unidentified; however, the inability to activate AMPK and the resulting mTOR hyperactivation has been detected in PJS-associated lesions. Therefore, targeting LKB1 in cancer is now mainly focusing on the activation of AMPK and inactivation of mTOR. Preclinical in vitro and in vivo studies show encouraging results regarding these approaches, which have even progressed to the initiation of a few clinical trials. In this review, we describe the functions, regulation and downstream signaling of LKB1, and its role in hereditary and sporadic cancers. In addition, we provide an overview of several AMPK activators, mTOR inhibitors and additional mechanisms to target LKB1 signaling, and describe the effect of these compounds on cancer cells. Overall, we will explain the current strategies attempting to find a way of treating LKB1-associated cancer.
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Affiliation(s)
- S E Korsse
- Dept. of Gastroenterology and Hepatology, Erasmus Medical University Center, Rotterdam, The Netherlands
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18
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Van Meter M, Seluanov A, Gorbunova V. Forever young? Exploring the link between rapamycin, longevity and cancer. Cell Cycle 2012; 11:4296-7. [PMID: 23152185 PMCID: PMC3552905 DOI: 10.4161/cc.22868] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
| | - Andrei Seluanov
- Department of Biology; University of Rochester; Rochester, NY USA
| | - Vera Gorbunova
- Department of Biology; University of Rochester; Rochester, NY USA
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19
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Blagosklonny MV. Rapalogs in cancer prevention: anti-aging or anticancer? Cancer Biol Ther 2012; 13:1349-54. [PMID: 23151465 DOI: 10.4161/cbt.22859] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Common cancer is an age-related disease. Slow aging is associated with reduced and delayed carcinogenesis. Calorie restriction (CR), the most studied anti-aging intervention, prevents cancer by slowing down the aging process. Evidence is emerging that CR decelerates aging by deactivating MTOR (Target of Rapamycin). Rapamycin and other rapalogs suppress cellular senescence, slow down aging and postpone age-related diseases including cancer. At the same time, rapalogs are approved for certain cancer treatments. Can cancer prevention be explained by direct targeting of cancer cells? Or does rapamycin prevent cancer indirectly through slowing down the aging process? Increasing evidence points to the latter scenario.
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20
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Abstract
National Cancer Institute has announced 24 provocative questions on cancer. Here I try to answer some of them by linking the dots of existing knowledge.
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Affiliation(s)
- Mikhail V Blagosklonny
- Department of Cell Stress Biology, Roswell Park Cancer Institute, BLSC, L3-312, Elm and Carlton Streets, Buffalo, NY 14263, USA.
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21
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Gage M, Wattendorf D, Henry LR. Translational advances regarding hereditary breast cancer syndromes. J Surg Oncol 2012; 105:444-51. [PMID: 22441895 DOI: 10.1002/jso.21856] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Approximately 5-10% of breast cancers may be inheritable, up to 90% of which are due to mutations in BRCA1 and BRCA2. A substantial minority are caused by non-BRCA mutations, such as TP53, PTEN, STK11, CHEK2, ATM, BRIP1, and PALB2 mutations. This review highlights translational research advances with regard to the development of probabilistic models for hereditary breast cancer syndromes, the identification of specific genetic mutations responsible for these syndromes, as well as their testing and interpretations.
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Affiliation(s)
- M Gage
- National Capital Area Breast Care Center, National Naval Medical Center, Bethesda, Maryland, USA
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22
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Antitumor effect of the mTOR inhibitor everolimus in combination with trastuzumab on human breast cancer stem cells in vitro and in vivo. Tumour Biol 2012; 33:1349-62. [DOI: 10.1007/s13277-012-0383-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 03/14/2012] [Indexed: 01/24/2023] Open
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23
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Fierz Y, Novosyadlyy R, Vijayakumar A, Yakar S, LeRoith D. Mammalian target of rapamycin inhibition abrogates insulin-mediated mammary tumor progression in type 2 diabetes. Endocr Relat Cancer 2010; 17:941-51. [PMID: 20801951 PMCID: PMC4082826 DOI: 10.1677/erc-10-0091] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Type 2 diabetes increases breast cancer risk and mortality, and hyperinsulinemia is a major mediator of this effect. The mammalian target of rapamycin (mTOR) is activated by insulin and is a key regulator of mammary tumor progression. Pharmacological mTOR inhibition suppresses tumor growth in numerous mammary tumor models in the non-diabetic setting. However, the role of the mTOR pathway in type 2 diabetes-induced tumor growth remains elusive. Herein, we investigated whether the mTOR pathway is implicated in insulin-induced mammary tumor progression in a transgenic mouse model of type 2 diabetes (MKR mice) and evaluated the impact of mTOR inhibition on the diabetic state. Mammary tumor progression was studied in the double transgenic MMTV-Polyoma Virus middle T antigen (PyVmT)/MKR mice and by orthotopic inoculation of PyVmT- and Neu/ErbB2-driven mammary tumor cells (Met-1 and MCNeuA cells respectively). mTOR inhibition by rapamycin markedly suppressed tumor growth in both wild-type and MKR mice. In diabetic animals, however, the promoting action of insulin on tumor growth was completely blunted by rapamycin, despite a worsening of the carbohydrate and lipid metabolism. Taken together, pharmacological mTOR blockade is sufficient to abrogate mammary tumor progression in the setting of hyperinsulinemia, and thus mTOR inhibitors may be an attractive therapeutic modality for breast cancer patients with type 2 diabetes. Careful monitoring of the metabolic state, however, is important as dose adaptations of glucose- and/or lipid-lowering therapy might be necessary.
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Affiliation(s)
- Yvonne Fierz
- Division of Endocrinology, Diabetes and Bone Diseases, The Samuel Bronfman Department of Medicine, Mount Sinai School of Medicine, New York, New York 10029, USA
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24
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Restuccia DF, Hemmings BA. From man to mouse and back again: advances in defining tumor AKTivities in vivo. Dis Model Mech 2010; 3:705-20. [PMID: 20940316 DOI: 10.1242/dmm.004671] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
AKT hyperactivation is a common event in human cancers, and inhibition of oncogenic AKT activation is a major goal of drug discovery programs. Mouse tumor models that replicate AKT activation typical of human cancers provide a powerful means by which to investigate mechanisms of oncogenic signaling, identify potential therapeutic targets and determine treatment regimes with maximal therapeutic efficacy. This Perspective highlights recent advances using in vivo studies that reveal how AKT signaling supports tumor formation, cooperates with other mutations to promote tumor progression and facilitates tumor-cell dissemination, focusing on well-characterized prostate carcinoma mouse models that are highly sensitive to AKT activation. The implications of these findings on the therapeutic targeting of AKT and potential new drug targets are also explored.
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Affiliation(s)
- David F Restuccia
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland.
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25
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Anisimov VN, Zabezhinski MA, Popovich IG, Piskunova TS, Semenchenko AV, Tyndyk ML, Yurova MN, Antoch MP, Blagosklonny MV. Rapamycin extends maximal lifespan in cancer-prone mice. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 176:2092-7. [PMID: 20363920 DOI: 10.2353/ajpath.2010.091050] [Citation(s) in RCA: 198] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Aging is associated with obesity and cancer. Calorie restriction both slows down aging and delays cancer. Evidence has emerged that the nutrient-sensing mammalian target of rapamycin (mTOR) pathway is involved in cellular and organismal aging. Here we show that the mTOR inhibitor rapamycin prevents age-related weight gain, decreases rate of aging, increases lifespan, and suppresses carcinogenesis in transgenic HER-2/neu cancer-prone mice. Rapamycin dramatically delayed tumor onset as well as decreased the number of tumors per animal and tumor size. We suggest that, by slowing down organismal aging, rapamycin delays cancer.
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Affiliation(s)
- Vladimir N Anisimov
- Department of Carcinogenesis and Oncogerontology, N.N. Petrov Research Institute of Oncology, St. Petersburg, Russia.
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26
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Efferson CL, Winkelmann CT, Ware C, Sullivan T, Giampaoli S, Tammam J, Patel S, Mesiti G, Reilly JF, Gibson RE, Buser C, Yeatman T, Coppola D, Winter C, Clark EA, Draetta GF, Strack PR, Majumder PK. Downregulation of Notch pathway by a gamma-secretase inhibitor attenuates AKT/mammalian target of rapamycin signaling and glucose uptake in an ERBB2 transgenic breast cancer model. Cancer Res 2010; 70:2476-84. [PMID: 20197467 DOI: 10.1158/0008-5472.can-09-3114] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
ERBB2/neu and Notch signaling are known to be deregulated in many human cancers. However, pathway cross-talk and dependencies are not well understood. In this study, we use an ERBB2-transgenic mouse model of breast cancer (neuT) to show that Notch signaling plays a critical role in tumor maintenance. Inhibition of the Notch pathway with a gamma-secretase inhibitor (GSI) decreased both the Notch and the mammalian target of rapamycin/AKT pathways. Antitumor activity resulting from GSI treatment was associated with decreased cell proliferation as measured by Ki67 and decreased expression of glucose transporter Glut1. Positron emission tomography (PET) imaging showed that the functional consequences of decreased Glut1 translated to reduced glucose uptake and correlated with antitumor effects as measured by micro-computed tomography imaging. The decrease of Glut1 in neuT tumors was also observed in several human breast cancer cell lines following GSI treatment. We provide evidence that approximately 27% of ERBB2-positive human breast cancer specimens display high expression of HES1, phospho-S6RP, and GLUT1. Together, these results suggest that pathways downstream of Notch signaling are, at least in part, responsible for promoting tumor growth in neuT and also active in both neuT and a subset of human breast cancers. These findings suggest that GSI may provide therapeutic benefit to a subset of ERBB2-positive breast cancers and that [(18)F]FDG-PET imaging may be useful in monitoring clinical response.
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Affiliation(s)
- Clay L Efferson
- Department of Oncology, Pharmacology, Laboratory of Animal Research, Merck Research Laboratories, Boston, Massachusetts 02115, USA
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27
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Dean-Colomb W, Esteva FJ. Treatment of Her2-Positive Breast Cancer: What’s on the Horizon. CURRENT BREAST CANCER REPORTS 2010. [DOI: 10.1007/s12609-010-0003-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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28
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Miller TW, Forbes JT, Shah C, Wyatt SK, Manning HC, Olivares MG, Sanchez V, Dugger TC, de Matos Granja N, Narasanna A, Cook RS, Kennedy JP, Lindsley CW, Arteaga CL. Inhibition of mammalian target of rapamycin is required for optimal antitumor effect of HER2 inhibitors against HER2-overexpressing cancer cells. Clin Cancer Res 2009; 15:7266-76. [PMID: 19934303 DOI: 10.1158/1078-0432.ccr-09-1665] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
PURPOSE A significant fraction of HER2-overexpressing breast cancers exhibit resistance to the HER2 antibody trastuzumab. Hyperactivity of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway confers trastuzumab resistance, and mammalian target of rapamycin (mTOR) is a major downstream effector of PI3K/AKT. Therefore, we examined whether mTOR inhibitors synergize with trastuzumab. EXPERIMENTAL DESIGN Immunocompetent mice bearing HER2(+) mammary tumors were treated with trastuzumab, the mTOR inhibitor rapamycin, or the combination. Mice were imaged for tumor cell death using an optical Annexin-V probe and with [(18)F]FDG positron emission tomography. The signaling and growth effects of the mTOR inhibitor RAD001 on HER2(+) cells treated with trastuzumab or lapatinib were evaluated. RESULTS Treatment of mice with trastuzumab plus rapamycin was more effective than single-agent treatments, inducing complete regression of 26 of 26 tumors. The combination induced tumor cell death (Annexin-V binding) and inhibited FDG uptake. Rapamycin inhibited mTOR and tumor cell proliferation as determined by phosphorylated S6 and Ki-67 immunohistochemistry, respectively. In culture, the combination of RAD001 plus trastuzumab inhibited cell growth more effectively than either drug alone. Trastuzumab partially decreased PI3K but not mTOR activity. Knockdown of TSC2 resulted in HER2-independent activation of mTOR and dampened the response to trastuzumab and lapatinib. Treatment with the HER2 inhibitor lapatinib decreased phosphorylated S6 and growth in TSC2-expressing cells but not in TSC2-knockdown cells. CONCLUSIONS Inhibition of PI3K and mTOR are required for the growth-inhibitory effect of HER2 antagonists. These findings collectively support the combined use of trastuzumab and mTOR inhibitors for the treatment of HER2(+) breast cancer.
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Affiliation(s)
- Todd W Miller
- Department of Medicine, Vanderbilt University, Nashville, Tennessee, USA
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29
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Dowling RJO, Pollak M, Sonenberg N. Current status and challenges associated with targeting mTOR for cancer therapy. BioDrugs 2009; 23:77-91. [PMID: 19489650 DOI: 10.2165/00063030-200923020-00002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway plays a critical role in the regulation of cellular growth, survival, and proliferation. Inappropriate activation of PI3K/Akt/mTOR signaling can promote a cellular environment that is favorable for transformation. In fact, dysregulation of this pathway, as a result of genetic mutations and amplifications, is implicated in a variety of human cancers. Therefore, mTOR has emerged as a key target for the treatment of cancer, particularly in the treatment of tumors that exhibit increased mTOR signaling as a result of genetic lesions. The immunosuppressant sirolimus (rapamycin) directly inhibits mTOR activity and suppresses the growth of cancer cells in vitro and in vivo. As a result, a number of sirolimus derivatives have been developed as anti-cancer therapies, and these compounds are currently under investigation in phase I-III clinical trials. In this review, we summarize the use of sirolimus derivatives in clinical trials and address some of the challenges associated with targeting mTOR for the treatment of human cancer.
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Affiliation(s)
- Ryan J O Dowling
- Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec, Canada
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30
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Abstract
In contrast with cytotoxic agents that do not differentiate between normal proliferating and tumour cells, targeted therapies primarily exert their actions in cancer cells. Initiation and maintenance of tumours are due to genetic alterations in specific loci. The identification of the genes in which these alterations occur has opened new opportunities for cancer treatment. The PI3K (phosphoinositide 3-kinase) pathway is often overactive in human cancers, and various genetic alterations have been found to cause this. In all cases, PI3K inhibition is considered to be one of the most promising targeted therapies for cancer treatment. The present mini-review provides an update on new PI3K inhibitors currently in or entering clinical development. Recent discoveries, challenges and future prospects will be discussed.
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Pinto-Leite R, Botelho P, Ribeiro E, Oliveira PA, Santos L. Effect of sirolimus on urinary bladder cancer T24 cell line. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2009; 28:3. [PMID: 19128503 PMCID: PMC2628648 DOI: 10.1186/1756-9966-28-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Accepted: 01/07/2009] [Indexed: 12/18/2022]
Abstract
Background Sirolimus is recently reported to have antitumour effects on a large variety of cancers. The present study was performed to investigate sirolimus's ability to inhibit growth in T24 bladder cancer cells. Methods T24 bladder cancer cells were treated with various concentrations of sirolimus. MTT assay was used to evaluate the proliferation inhibitory effect on T24 cell line. The viability of T24 cell line was determined by Trypan blue exclusion analysis. Results Sirolimus inhibits the growth of bladder carcinoma cells and decreases their viability. Significant correlations were found between cell proliferation and sirolimus concentration (r = 0.830; p < 0.01) as well as between cell viability and sirolimus concentration (r = -0.896; p < 0.01). Conclusion Sirolimus has an anti-proliferation effect on the T24 bladder carcinoma cell line. The information from our results is useful for a better understanding sirolimus's anti-proliferative activity in the T24 bladder cancer cell line.
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Affiliation(s)
- Rosario Pinto-Leite
- Genetic Service, Cytogenetic laboratory, Hospital center of Trás-os-Montes and Alto Douro, Vila Real, Portugal.
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Aronovitz A, Josefson J, Fisher A, Newman M, Hughes E, Chen F, Moons DS, Kiyokawa H, Lowe WL. Rapamycin inhibits growth factor-induced cell cycle regulation in pancreatic beta cells. J Investig Med 2009; 56:985-96. [PMID: 19105244 DOI: 10.2310/jim.0b013e31818ce763] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A progressive decline in islet function is a major obstacle to success of islet transplantation. The cause of this decline is islet function is unclear, but immunosuppressive agents may contribute. Insulin-like growth factor-I (IGF-I) and betacellulin are important for islet cell survival and/or proliferation. In the present study, we performed studies of IGF-I and betacellulin on progression of islet cells through the cell cycle and the impact of immunosuppressive agents. Treatment of INS-1 cells for 24 hours with 20 ng/mL betacellulin or 50 ng/mL IGF-1 increased cells in S phase by ~2-fold. Treatment of INS-1 cells with IGF-I or betacellulin also increased cyclin D1 expression and nuclear exclusion of the cyclindependent kinase inhibitors p21(Cip1) and p27(Kip1). In INS-1 cells and islets, betacellulin- and IGF-I increased the increase in p70(s6 kinase) phosphorylation stimulated by betacellulin- and IGF-I in INS-1 cells. Rapamycin also inhibited betacellulin- and IGF-I IN IGF-1 cells. Rapamycin also inhibited betacellulin- and IGF-I-induced entry of cells into S phase and 5'-Bromo-2'-deoxyuridine incorporation as well as the effect of betacellulin and IGF-I on cyclin D1 expression and nuclear exclusion of p21(Cip1) and p(27Kip1). Together, these data suggest that the effect of betacellulin and IGF-I on islet cell growth and proliferation is mediated, in part, via signaling through mammalian target of rapamycin. As rapamycin is used to treat islet transplant recipients, these results suggest that rapamycin could have deleterious effects on islet proliferation and function over time.
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Affiliation(s)
- Amy Aronovitz
- Department of Medicine, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, chicago, IL 60611, USA
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Lam PB, Burga LN, Wu BP, Hofstatter EW, Lu KP, Wulf GM. Prolyl isomerase Pin1 is highly expressed in Her2-positive breast cancer and regulates erbB2 protein stability. Mol Cancer 2008; 7:91. [PMID: 19077306 PMCID: PMC2632646 DOI: 10.1186/1476-4598-7-91] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Accepted: 12/15/2008] [Indexed: 01/12/2023] Open
Abstract
Overexpression of HER-2/Neu occurs in about 25–30% of breast cancer patients and is indicative of poor prognosis. While Her2/Neu overexpression is primarily a result of erbB2 amplification, it has recently been recognized that erbB2 levels are also regulated on the protein level. However, factors that regulate Her2/Neu protein stability are less well understood. The prolyl isomerase Pin1 catalyzes the isomerization of specific pSer/Thr-Pro motifs that have been phosphorylated in response to mitogenic signaling. We have previously reported that Pin1-catalyzed post-phosphorylational modification of signal transduction modulates the oncogenic pathways downstream from c-neu. The goal of this study was to examine the expression of prolyl isomerase Pin1 in human Her2+ breast cancer, and to study if Pin1 affects the expression of Her2/Neu itself.
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Affiliation(s)
- Prudence B Lam
- Cancer Biology Program, Division of Hematology/Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, NRB 1030c, Boston, MA 02215, USA.
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Dean-Colomb W, Esteva FJ. Her2-positive breast cancer: herceptin and beyond. Eur J Cancer 2008; 44:2806-12. [PMID: 19022660 DOI: 10.1016/j.ejca.2008.09.013] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Accepted: 09/23/2008] [Indexed: 12/25/2022]
Abstract
Breast cancer accounts for approximately 30% of all new cancer cases each year, with an annual incidence of approximately 200,000. Additionally, almost 25% of breast cancers are noted to overexpress Her2, which is an epidermal growth factor receptor. Overexpression of Her2 has been associated with a more aggressive phenotype with decreased survival. Trastuzumab, a recombinant monoclonal antibody against the Her2 receptor, is the only FDA-approved targeted agent for treatment of Her2-overexpressing breast cancer. However, despite the great success achieved with trastuzumab, many women will either not respond or eventually progress despite trastuzumab treatment. As a result, significant efforts have been applied to finding other therapies besides trastuzumab for the treatment of Her2-positive breast cancer. Work has been directed at trying to elucidate the exact mechanism of resistance to trastuzumab and identifying ways to overcome them, at increasing the efficacy of trastuzumab by combining it with other therapeutic agents and at investigating other novel agents.
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Affiliation(s)
- Windy Dean-Colomb
- Department of Cancer Medicine, UT MD Anderson Cancer Center, Houston, TX 77030, USA
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Campeau PM, Foulkes WD, Tischkowitz MD. Hereditary breast cancer: new genetic developments, new therapeutic avenues. Hum Genet 2008; 124:31-42. [PMID: 18575892 DOI: 10.1007/s00439-008-0529-1] [Citation(s) in RCA: 204] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Accepted: 06/13/2008] [Indexed: 12/24/2022]
Abstract
Six genes confer a high risk for developing breast cancer (BRCA1/2, TP53, PTEN, STK11, CDH1). Both BRCA1 and BRCA2 have DNA repair functions, and BRCA1/2 deficient tumors are now being targeted by poly(ADP-ribose) polymerase inhibitors. Other genes conferring an increased risk for breast cancer include ATM, CHEK2, PALB2, BRIP1 and genome-wide association studies have identified lower penetrance alleles including FGFR2, a minor allele of which is associated with breast cancer. We review recent findings related to the function of some of these genes, and discuss how they can be targeted by various drugs. Gaining deeper insights in breast cancer susceptibility will improve our ability to identify those families at increased risk and permit the development of new and more specific therapeutic approaches.
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Affiliation(s)
- Philippe M Campeau
- Department of Medical Genetics, McGill University Health Centre, McGill University, Montreal, QC, Canada.
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Abstract
Autophagy is an evolutionary conserved mechanism in eukaryotic cells that is known to process redundant or defective cellular proteins and organelles. The recent renewal of interest in autophagy research has led to a significant expansion in our understanding of the importance of autophagy in cellular health and disease. This invited review summarizes key elements of autophagy research, emphasizes those of particular interest to gastroenterologists, and offers insights into present and future research directions.
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Vazquez-Martin A, Oliveras-Ferraros C, Colomer R, Brunet J, Menendez JA. Low-scale phosphoproteome analyses identify the mTOR effector p70 S6 kinase 1 as a specific biomarker of the dual-HER1/HER2 tyrosine kinase inhibitor lapatinib (Tykerb) in human breast carcinoma cells. Ann Oncol 2008; 19:1097-109. [PMID: 18283037 DOI: 10.1093/annonc/mdm589] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Discovery of key proliferative and/or survival cascades closely linked to the biological effects of human epidermal growth factor receptor (HER) 1 (erbB-1) and/or HER2 (erbB-2) inhibitors may identify a priori mechanisms responsible for the development of acquired resistance in breast cancer disease. Here, we took advantage of a semiquantitative protein array technology to identify intracellular oncogenic kinases that distinctively correlate with breast cancer cell sensitivity/resistance to the dual-HER1/HER2 tyrosine kinase inhibitor lapatinib (Tykerb(R)). MATERIALS AND METHODS MCF-7 cells were forced to overexpress HER2 following stable transduction with pBABE-HER2 retroviruses. The Human Phospho-MAPK Array Proteome Profilertrade mark (R&D Systems) was used to molecularly assess the effects of both the mono-HER2 inhibitor trastuzumab (Herceptintrade mark) and the dual-HER1/HER2 inhibitor lapatinib on 21 different oncogenic kinases. A model of acquired resistance to lapatinib (MCF-7/HER2-Lap10 cells) was established by chronically exposing MCF-7/HER2 cells to increasing concentrations of lapatinib for >10 months. RESULTS Treatment of MCF-7/HER2 cells with either trastuzumab or lapatinib similarly impaired HER2-enhanced activation status (i.e. phosphorylation) of the mitogen-activated protein kinases, c-Jun N-terminal kinases 1-3 and p38alpha/beta/gamma/delta and of the serine/threonine kinases AKT, glycogen synthase kinase-3, p90 ribosomal s6 kinase1/2, and mitogen- and stress-activated protein kinase1/2. Trastuzumab was less effective than lapatinib at blocking extracellular-signal regulated kinase (ERK) 1/2 and, notably, it failed to deactivate the mammalian target of rapamycin (mTOR) effector p70S6K1. Conversely, lapatinib treatment caused a drastic decrease in the phosphorylation of p70S6K1 at ERK1/2-regulated sites (Thr(421)/Ser(424)) and, as a consequence, p70S6K1 activity measured by its phospho-Thr(389) levels was abolished. The mTOR inhibitor rapamycin was found to supraadditively increase lapatinib efficacy in MCF-7/HER2 cells [ approximately 10-fold enhancement; combination index (CI(50)) = 0.243 < 1.0 = additivity, P < 0.001] but not in p70S6K1 gene-amplified MCF-7 parental cells ( approximately 1.3-fold enhancement; CI(50) = 0.920 congruent with 1.0 = additivity). Lapatinib-resistant MCF-7/HER2-Lap10 cells, which are capable of growing in the continuous presence of 10 microM lapatinib without significant effects on cell viability, notably exhibited a lapatinib-insensitive hyperphosphorylation of p70S6K1. Rapamycin cotreatment suppressed p70S6K1 hyperactivation and synergistically resensitized MCF-7/HER2-Lap10 cells to lapatinib (>20-fold increase in lapatinib-induced cytotoxicity; CI(50) = 0.175 < 1.0 = additivity). CONCLUSIONS Serine-threonine kinase p70S6K1, a marker for mTOR activity that regulates protein translation, constitutes a specific biomarker for the biological effects of the dual-HER1/HER2 inhibitor lapatinib. The clinical implications of our data are that the efficacy of lapatinib might be enhanced with therapies that target the mTOR pathway. Rapamycin analogues such as CCI-779 (Temsirolimus) and RAD001 (Everolimus) may warrant further clinical evaluation to effectively delay or prevent the development of acquired resistance to lapatinib in HER2-positive breast cancer patients.
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Yeager N, Brewer C, Cai KQ, Xu XX, Di Cristofano A. Mammalian target of rapamycin is the key effector of phosphatidylinositol-3-OH-initiated proliferative signals in the thyroid follicular epithelium. Cancer Res 2008; 68:444-9. [PMID: 18199538 DOI: 10.1158/0008-5472.can-07-3030] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Activation of the phosphatidylinositol-3-OH kinase (PI3K) signaling cascade is becoming increasingly recognized as a common feature of thyroid follicular neoplasms. We have recently shown that conditional loss of Pten in the mouse thyroid follicular cells is sufficient to stimulate continuous autonomous growth, leading to a homogeneously hyperplastic gland and to the development of follicular adenomas. Because the PI3K/AKT cascade can activate a plethora of different signaling pathways, it is still unclear which of these may represent the key mitogenic output of PI3K-initiated signaling. Here, we show that the in vivo proliferative response to chronic PI3K activation profoundly relies on the activation of the mammalian target of rapamycin (mTOR)/S6K1 axis, and that mTOR inhibition in Pten mutant mice and cells restores virtually normal proliferation rates, despite the presence of still elevated Akt activity, at least in part by down-regulating cyclins D1 and D3, and without affecting cell survival.
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Affiliation(s)
- Nicole Yeager
- Human Genetics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA
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