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Zhao T, Fan J, Abu-Zaid A, Burley SK, Zheng XS. Nuclear mTOR Signaling Orchestrates Transcriptional Programs Underlying Cellular Growth and Metabolism. Cells 2024; 13:781. [PMID: 38727317 PMCID: PMC11083943 DOI: 10.3390/cells13090781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 04/26/2024] [Accepted: 05/01/2024] [Indexed: 05/13/2024] Open
Abstract
mTOR is a central regulator of cell growth and metabolism in response to mitogenic and nutrient signals. Notably, mTOR is not only found in the cytoplasm but also in the nucleus. This review highlights direct involvement of nuclear mTOR in regulating transcription factors, orchestrating epigenetic modifications, and facilitating chromatin remodeling. These effects intricately modulate gene expression programs associated with growth and metabolic processes. Furthermore, the review underscores the importance of nuclear mTOR in mediating the interplay between metabolism and epigenetic modifications. By integrating its functions in nutrient signaling and gene expression related to growth and metabolism, nuclear mTOR emerges as a central hub governing cellular homeostasis, malignant transformation, and cancer progression. Better understanding of nuclear mTOR signaling has the potential to lead to novel therapies against cancer and other growth-related diseases.
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Affiliation(s)
- Tinghan Zhao
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Jialin Fan
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Ahmed Abu-Zaid
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Stephen K. Burley
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
- RCSB Protein Data Bank and Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, 174 Frelinghuysen Road, Piscataway, NJ 08854, USA
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 174 Frelinghuysen Road, Piscataway, NJ 08854, USA
| | - X.F. Steven Zheng
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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Chen Y, Han L, Dufour CR, Alfonso A, Giguère V. Canonical and Nuclear mTOR Specify Distinct Transcriptional Programs in Androgen-Dependent Prostate Cancer Cells. Mol Cancer Res 2024; 22:113-124. [PMID: 37889103 DOI: 10.1158/1541-7786.mcr-23-0087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 09/21/2023] [Accepted: 10/24/2023] [Indexed: 10/28/2023]
Abstract
mTOR is a serine/threonine kinase that controls prostate cancer cell growth in part by regulating gene programs associated with metabolic and cell proliferation pathways. mTOR-mediated control of gene expression can be achieved via phosphorylation of transcription factors, leading to changes in their cellular localization and activities. mTOR also directly associates with chromatin in complex with transcriptional regulators, including the androgen receptor (AR). Nuclear mTOR (nmTOR) has been previously shown to act as a transcriptional integrator of the androgen signaling pathway in association with the chromatin remodeling machinery, AR, and FOXA1. However, the contribution of cytoplasmic mTOR (cmTOR) and nmTOR and the role played by FOXA1 in this process remains to be explored. Herein, we engineered cells expressing mTOR tagged with nuclear localization and export signals dictating mTOR localization. Transcriptome profiling in AR-positive prostate cancer cells revealed that nmTOR generally downregulates a subset of the androgen response pathway independently of its kinase activity, while cmTOR upregulates a cell cycle-related gene signature in a kinase-dependent manner. Biochemical and genome-wide transcriptomic analyses demonstrate that nmTOR functionally interacts with AR and FOXA1. Ablation of FOXA1 reprograms the nmTOR cistrome and transcriptome of androgen responsive prostate cancer cells. This works highlights a transcriptional regulatory pathway in which direct interactions between nmTOR, AR and FOXA1 dictate a combinatorial role for these factors in the control of specific gene programs in prostate cancer cells. IMPLICATIONS The finding that canonical and nuclear mTOR signaling pathways control distinct gene programs opens therapeutic opportunities to modulate mTOR activity in prostate cancer cells.
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Affiliation(s)
- Yonghong Chen
- Goodman Cancer Institute, McGill University, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine and Health Sciences, McGill University, Montréal, Québec, Canada
| | - Lingwei Han
- Goodman Cancer Institute, McGill University, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine and Health Sciences, McGill University, Montréal, Québec, Canada
| | | | - Anthony Alfonso
- Goodman Cancer Institute, McGill University, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine and Health Sciences, McGill University, Montréal, Québec, Canada
| | - Vincent Giguère
- Goodman Cancer Institute, McGill University, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine and Health Sciences, McGill University, Montréal, Québec, Canada
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Chen Y, Dufour CR, Han L, Li T, Xia H, Giguère V. Hierarchical Phosphorylation of HOXB13 by mTOR Dictates Its Activity and Oncogenic Function in Prostate Cancer. Mol Cancer Res 2023; 21:1050-1063. [PMID: 37409967 PMCID: PMC10544006 DOI: 10.1158/1541-7786.mcr-23-0086] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 05/23/2023] [Accepted: 06/27/2023] [Indexed: 07/07/2023]
Abstract
Dysregulation of mTOR signaling plays a critical role in promoting prostate cancer growth. HOXB13, a homeodomain transcription factor, is known to influence the androgen response and prostate cancer development. Recently, HOXB13 was found to complex with mTOR on chromatin. However, the functional crosstalk between HOXB13 and mTOR remains elusive. We now report that mTOR directly interacts with and hierarchically phosphorylates HOXB13 at threonine 8 and 41 then serine 31 to promote its interaction with the E3 ligase SKP2 while enhancing its oncogenic properties. Expression of HOXB13 harboring phosphomimetic mutations at the mTOR-targeted sites stimulates prostate cancer cellular growth both in vitro and in murine xenografts. Transcriptional profiling studies revealed a phospho-HOXB13-dependent gene signature capable of robustly discriminating between normal prostate tissues, primary and metastatic prostate cancer samples. This work uncovers a previously unanticipated molecular cascade by which mTOR directly phosphorylates HOXB13 to dictate a specific gene program with oncogenic implications in prostate cancer. IMPLICATIONS Control of HOXB13 transcriptional activity via its direct phosphorylation by the mTOR kinase is a potential therapeutic avenue for the management of advanced prostate cancer.
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Affiliation(s)
- Yonghong Chen
- Goodman Cancer Institute, McGill University, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine and Health Sciences, McGill University, Montréal, Québec, Canada
| | | | - Lingwei Han
- Goodman Cancer Institute, McGill University, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine and Health Sciences, McGill University, Montréal, Québec, Canada
| | - Ting Li
- Goodman Cancer Institute, McGill University, Montréal, Québec, Canada
| | - Hui Xia
- Goodman Cancer Institute, McGill University, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine and Health Sciences, McGill University, Montréal, Québec, Canada
| | - Vincent Giguère
- Goodman Cancer Institute, McGill University, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine and Health Sciences, McGill University, Montréal, Québec, Canada
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Raith F, O’Donovan DH, Lemos C, Politz O, Haendler B. Addressing the Reciprocal Crosstalk between the AR and the PI3K/AKT/mTOR Signaling Pathways for Prostate Cancer Treatment. Int J Mol Sci 2023; 24:ijms24032289. [PMID: 36768610 PMCID: PMC9917236 DOI: 10.3390/ijms24032289] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/17/2023] [Accepted: 01/20/2023] [Indexed: 01/27/2023] Open
Abstract
The reduction in androgen synthesis and the blockade of the androgen receptor (AR) function by chemical castration and AR signaling inhibitors represent the main treatment lines for the initial stages of prostate cancer. Unfortunately, resistance mechanisms ultimately develop due to alterations in the AR pathway, such as gene amplification or mutations, and also the emergence of alternative pathways that render the tumor less or, more rarely, completely independent of androgen activation. An essential oncogenic axis activated in prostate cancer is the phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway, as evidenced by the frequent alterations of the negative regulator phosphatase and tensin homolog (PTEN) and by the activating mutations in PI3K subunits. Additionally, crosstalk and reciprocal feedback loops between androgen signaling and the PI3K/AKT/mTOR signaling cascade that activate pro-survival signals and play an essential role in disease recurrence and progression have been evidenced. Inhibitors addressing different players of the PI3K/AKT/mTOR pathway have been evaluated in the clinic. Only a limited benefit has been reported in prostate cancer up to now due to the associated side effects, so novel combination approaches and biomarkers predictive of patient response are urgently needed. Here, we reviewed recent data on the crosstalk between AR signaling and the PI3K/AKT/mTOR pathway, the selective inhibitors identified, and the most advanced clinical studies, with a focus on combination treatments. A deeper understanding of the complex molecular mechanisms involved in disease progression and treatment resistance is essential to further guide therapeutic approaches with improved outcomes.
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Affiliation(s)
- Fabio Raith
- Research & Development, Pharmaceuticals, Bayer AG, Müllerstr. 178, 13353 Berlin, Germany
| | - Daniel H. O’Donovan
- Research & Development, Pharmaceuticals, Bayer AG, Müllerstr. 178, 13353 Berlin, Germany
| | - Clara Lemos
- Bayer Research and Innovation Center, Bayer US LLC, 238 Main Street, Cambridge, MA 02142, USA
| | - Oliver Politz
- Research & Development, Pharmaceuticals, Bayer AG, Müllerstr. 178, 13353 Berlin, Germany
| | - Bernard Haendler
- Research & Development, Pharmaceuticals, Bayer AG, Müllerstr. 178, 13353 Berlin, Germany
- Correspondence: ; Tel.: +49-30-2215-41198
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Miller KJ, Henry I, Maylin Z, Smith C, Arunachalam E, Pandha H, Asim M. A compendium of Androgen Receptor Variant 7 target genes and their role in Castration Resistant Prostate Cancer. Front Oncol 2023; 13:1129140. [PMID: 36937454 PMCID: PMC10014620 DOI: 10.3389/fonc.2023.1129140] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 02/13/2023] [Indexed: 03/05/2023] Open
Abstract
Persistent androgen receptor (AR) signalling is the main driver of prostate cancer (PCa). Truncated isoforms of the AR called androgen receptor variants (AR-Vs) lacking the ligand binding domain often emerge during treatment resistance against AR pathway inhibitors such as Enzalutamide. This review discusses how AR-Vs drive a more aggressive form of PCa through the regulation of some of their target genes involved in oncogenic pathways, enabling disease progression. There is a pressing need for the development of a new generation of AR inhibitors which can repress the activity of both the full-length AR and AR-Vs, for which the knowledge of differentially expressed target genes will allow evaluation of inhibition efficacy. This review provides a detailed account of the most common variant, AR-V7, the AR-V7 regulated genes which have been experimentally validated, endeavours to understand their relevance in aggressive AR-V driven PCa and discusses the utility of the downstream protein products as potential drug targets for PCa treatment.
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Affiliation(s)
| | | | - Zoe Maylin
- *Correspondence: Zoe Maylin, ; Mohammad Asim,
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Scholtes C, Dufour CR, Giguère V. Rapid immunoprecipitation mass spectrometry of endogenous protein (RIME) to identify chromatin-interactome in prostate cancer cells. STAR Protoc 2022; 3:101434. [PMID: 35693211 PMCID: PMC9184806 DOI: 10.1016/j.xpro.2022.101434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Rapid immunoprecipitation mass spectrometry of endogenous protein (RIME) is a technique to study protein complexes on chromatin. The protocol below describes specific steps for RIME analysis of the male human-derived prostate cancer cell line LNCaP. This approach can also be applied to other prostate cancer cell lines such as 22Rv1, DU145, and PC3. For other cell types, we recommend optimizing the number of cell culture plates to ensure adequate sample for mass spectrometry protein detection. For complete details on the use and execution of this protocol, please refer to Mohammed et al. (2016) and Dufour et al. (2022). Protocol for RIME-based chromatin interactome discovery in prostate cancer cells Double crosslinking chromatin immunoprecipitation of prostate cancer cells Protocol is validated for mTOR in distinct prostate cancer cell lines
Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
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