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Skolariki A, D’Costa J, Little M, Lord S. Role of PI3K/Akt/mTOR pathway in mediating endocrine resistance: concept to clinic. Explor Target Antitumor Ther 2022; 3:172-199. [PMID: 36046843 PMCID: PMC9400772 DOI: 10.37349/etat.2022.00078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 02/11/2022] [Indexed: 01/06/2023] Open
Abstract
The majority of breast cancers express the estrogen receptor (ER) and for this group of patients, endocrine therapy is the cornerstone of systemic treatment. However, drug resistance is common and a focus for breast cancer preclinical and clinical research. Over the past 2 decades, the PI3K/Akt/mTOR axis has emerged as an important driver of treatment failure, and inhibitors of mTOR and PI3K are now licensed for the treatment of women with advanced ER-positive breast cancer who have relapsed on first-line hormonal therapy. This review presents the preclinical and clinical data that led to this new treatment paradigm and discusses future directions.
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Affiliation(s)
- Aglaia Skolariki
- Department of Oncology, University of Oxford, Churchill Hospital, OX3 7LE Oxford, UK
| | - Jamie D’Costa
- Department of Oncology, University of Oxford, Churchill Hospital, OX3 7LE Oxford, UK
| | - Martin Little
- Department of Oncology, Churchill Hospital, OX3 7LE Oxford, UK
| | - Simon Lord
- Department of Oncology, University of Oxford, Churchill Hospital, OX3 7LE Oxford, UK
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Himes BE, Obraztsova K, Lian L, Shumyatcher M, Rue R, Atochina-Vasserman EN, Hur SK, Bartolomei MS, Evans JF, Krymskaya VP. Rapamycin-independent IGF2 expression in Tsc2-null mouse embryo fibroblasts and human lymphangioleiomyomatosis cells. PLoS One 2018; 13:e0197105. [PMID: 29758070 PMCID: PMC5951544 DOI: 10.1371/journal.pone.0197105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 04/26/2018] [Indexed: 11/19/2022] Open
Abstract
Lymphangioleiomyomatosis (LAM) is a rare, almost exclusively female lung disease linked to inactivating mutations in tuberous sclerosis complex 2 (TSC2), a tumor suppressor gene that controls cell metabolic state and growth via regulation of the mechanistic target of rapamycin (mTORC1) signaling. mTORC1 is frequently activated in human cancers and, although the mTORC1 inhibitor rapamycin has a cytostatic effect, it is, in general, unable to elicit a robust curative effect or tumor regression. Using RNA-Seq, we identified (1) Insulin-like Growth Factor (IGF2) as one of the genes with the highest fold-change difference between human TSC2-null and TSC2-expressing angiomyolipoma cells from a patient with LAM, and (2) the mouse IGF2 homolog Igf2, as a top-ranking gene according to fold change between Tsc2-/- and Tsc2+/+ mouse embryo fibroblasts (MEFs). We extended transcript-level findings to protein level, observing increased Igf2 protein expression and Igf2 secretion by Tsc2-/- MEFs. Increased Igf2 expression was not due to epigenetic imprinting, but was partially mediated through the Stat3 pathway and was completely insensitive to rapamycin treatment. An siRNA-mediated decrease of Igf2 resulted in decreased Stat3 phosphorylation, suggesting presence of an autocrine Igf2/Stat3 amplification cycle in Tsc2-/- MEFs. In human pulmonary LAM lesions and metastatic cell clusters, high levels of IGF2 were associated with mTORC1 activation. In addition, treatment of three primary IGF2-expressing LAM lung cell lines with rapamycin did not result in IGF2 level changes. Thus, targeting of IGF2 signaling may be of therapeutic value to LAM patients, particularly those who are unresponsive to rapamycin.
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Affiliation(s)
- Blanca E. Himes
- Department of Biostatistics, Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Kseniya Obraztsova
- Penn Center for Pulmonary Biology and Pulmonary, Allergy and Critical Care Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Lurong Lian
- Penn Center for Pulmonary Biology and Pulmonary, Allergy and Critical Care Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Maya Shumyatcher
- Department of Biostatistics, Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Ryan Rue
- Penn Center for Pulmonary Biology and Pulmonary, Allergy and Critical Care Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Elena N. Atochina-Vasserman
- Penn Center for Pulmonary Biology and Pulmonary, Allergy and Critical Care Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Stella K. Hur
- Epigenetics Institute and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Marisa S. Bartolomei
- Epigenetics Institute and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jilly F. Evans
- Penn Center for Pulmonary Biology and Pulmonary, Allergy and Critical Care Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Vera P. Krymskaya
- Penn Center for Pulmonary Biology and Pulmonary, Allergy and Critical Care Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Simpson A, Petnga W, Macaulay VM, Weyer-Czernilofsky U, Bogenrieder T. Insulin-Like Growth Factor (IGF) Pathway Targeting in Cancer: Role of the IGF Axis and Opportunities for Future Combination Studies. Target Oncol 2017; 12:571-597. [PMID: 28815409 PMCID: PMC5610669 DOI: 10.1007/s11523-017-0514-5] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Despite a strong preclinical rationale for targeting the insulin-like growth factor (IGF) axis in cancer, clinical studies of IGF-1 receptor (IGF-1R)-targeted monotherapies have been largely disappointing, and any potential success has been limited by the lack of validated predictive biomarkers for patient enrichment. A large body of preclinical evidence suggests that the key role of the IGF axis in cancer is in driving treatment resistance, via general proliferative/survival mechanisms, interactions with other mitogenic signaling networks, and class-specific mechanisms such as DNA damage repair. Consequently, combining IGF-targeted agents with standard cytotoxic agents, other targeted agents, endocrine therapies, or immunotherapies represents an attractive therapeutic approach. Anti-IGF-1R monoclonal antibodies (mAbs) do not inhibit IGF ligand 2 (IGF-2) activation of the insulin receptor isoform-A (INSR-A), which may limit their anti-proliferative activity. In addition, due to their lack of specificity, IGF-1R tyrosine kinase inhibitors are associated with hyperglycemia as a result of interference with signaling through the classical metabolic INSR-B isoform; this may preclude their use at clinically effective doses. Conversely, IGF-1/IGF-2 ligand-neutralizing mAbs inhibit proliferative/anti-apoptotic signaling via IGF-1R and INSR-A, without compromising the metabolic function of INSR-B. Therefore, combination regimens that include these agents may be more efficacious and tolerable versus IGF-1R-targeted combinations. Herein, we review the preclinical and clinical experience with IGF-targeted therapies to-date, and discuss the rationale for future combination approaches as a means to overcome treatment resistance.
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Affiliation(s)
- Aaron Simpson
- Department of Oncology, University of Oxford, Oxford, UK
| | | | | | | | - Thomas Bogenrieder
- Boehringer Ingelheim RCV, Dr. Boehringer Gasse 5-11, 1121, Vienna, Austria.
- Department of Urology, University Hospital Grosshadern, Ludwig-Maximilians-University, Marchioninistrasse 15, 81377, Munich, Germany.
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