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Pumar OYT, Zanotelli MR, Lin MCJ, Schmitt RR, Green KS, Rojas KS, Hwang IY, Cerione RA, Wilson KF. A multiprotein signaling complex sustains AKT and mTOR/S6K activity necessary for the survival of cancer cells undergoing stress. bioRxiv 2024:2023.01.03.522657. [PMID: 36711811 PMCID: PMC9881951 DOI: 10.1101/2023.01.03.522657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Cancer cells encounter stresses during tumor progression and metastatic spread, however, how they survive these challenges is not fully understood. We now identify a mechanism for cancer cell survival through the discovery of a multiprotein signaling complex that includes the GTPase Cdc42, the Cdc42 GEF/effector protein Dock7, AKT, mTOR and the mTORC1 regulatory partners TSC1, TSC2, and Rheb. This pro-survival signaling complex sustains the activated state of AKT by preventing its dephosphorylation at Ser473 during serum starvation, resulting in a low but critical activation of a Raptor-independent mTOR/S6K activity. We demonstrate that the Dock7 DHR1 domain, previously of unknown function, is responsible for preserving AKT phosphorylation through an interaction requiring its C2-like motif. Collectively, these findings help address long-standing questions of how Cdc42 signals mTOR activation by elucidating the unique functions of its signaling partner Dock7 as an AKT regulator necessary for resistance to anoikis and apoptosis in cancer cells.
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Affiliation(s)
| | | | - Miao-chong Joy Lin
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Rebecca R. Schmitt
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Kai Su Green
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Katherine S. Rojas
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Irene Y. Hwang
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Richard A. Cerione
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
- Department of Chemistry, Cornell University, Ithaca, NY 14853, USA
| | - Kristin F. Wilson
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
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Greene KS, Choi A, Chen M, Yang N, Li R, Qiu Y, Lukey MJ, Rojas KS, Shen J, Wilson KF, Katt WP, Whittaker GR, Cerione RA. Inhibiting Glutamine Metabolism Blocks Coronavirus Replication in Mammalian Cells. bioRxiv 2023:2023.09.27.559756. [PMID: 37808692 PMCID: PMC10557708 DOI: 10.1101/2023.09.27.559756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Developing therapeutic strategies against COVID-19 has gained widespread interest given the likelihood that new viral variants will continue to emerge. Here we describe one potential therapeutic strategy which involves targeting members of the glutaminase family of mitochondrial metabolic enzymes (GLS and GLS2), which catalyze the first step in glutamine metabolism, the hydrolysis of glutamine to glutamate. We show three examples where GLS expression increases during coronavirus infection of host cells, and another in which GLS2 is upregulated. The viruses hijack the metabolic machinery responsible for glutamine metabolism to generate the building blocks for biosynthetic processes and satisfy the bioenergetic requirements demanded by the 'glutamine addiction' of virus-infected host cells. We demonstrate how genetic silencing of glutaminase enzymes reduces coronavirus infection and that newer members of two classes of small molecule allosteric inhibitors targeting these enzymes, designated as SU1, a pan-GLS/GLS2 inhibitor, and UP4, which is specific for GLS, block viral replication in mammalian epithelial cells. Overall, these findings highlight the importance of glutamine metabolism for coronavirus replication in human cells and show that glutaminase inhibitors can block coronavirus infection and thereby may represent a novel class of anti-viral drug candidates. Teaser Inhibitors targeting glutaminase enzymes block coronavirus replication and may represent a new class of anti-viral drugs.
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3
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Teran OY, Lin MCJ, Zanotelli MR, Wilson KF, Cerione RA. Abstract 139: Dock7 regulates the AKT/mTOR pathway to promote survival and sustain the transformative properties of cancer cells. Cancer Res 2022. [DOI: 10.1158/1538-7445.am2022-139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Akt is a well-known target of mitogenic signaling, which is activated by phosphoinositide 3-kinase, PDK1 and mTORC2, and is commonly regarded as a master regulator of cell survival. However, there is still a good deal to learn regarding how Akt can promote survival when cancer cells are faced by the multitude of challenges they need to overcome during the process of malignant transformation. While investigating the role of Dock7, a Cdc42 and Rac guanine nucleotide exchange factor of the Dock180 family, in tumorigenesis, we discovered an unexpected connection between Dock7, Akt and cell survival. Specifically, we found that Dock7 is necessary for cancer cells to survive under the stressful conditions that arise due to the loss of a substratum or serum deprivation, through its ability to stabilize a low, basal level of Akt kinase activity. Dock7 binds to Akt, as well as associates with the known Akt substrate, TSC2, promoting its phosphorylation. Since the phosphorylation of TSC2 eliminates its ability to work with its partner TSC1 to deactivate the Rheb GTPase, a direct activator of mTORC1, we probed whether mTORC1 function is also necessary for Dock7-dependent cancer cell survival. Indeed, we determined that Dock7, as well as its signaling partner Cdc42, is required to maintain a functional level of S6 kinase activity, a downstream target of mTORC1, which was prevented by the mTORC1 inhibitor rapamycin. We further show an association between mTOR, Rheb and Dock7, but not Raptor, the defining component of mTORC1. Additionally, Raptor is dispensable for the Dock7-dependent S6 kinase activity, despite its rapamycin sensitivity. Together, these findings elucidate a novel Dock7-Akt-mTOR signaling node which promotes cancer cell survival in the absence of classical mTORC1 function to allow cells to overcome stresses faced during the development of cancer.
Citation Format: Oriana Y. Teran, Miao-chong J. Lin, Matthew R. Zanotelli, Kristin F. Wilson, Richard A. Cerione. Dock7 regulates the AKT/mTOR pathway to promote survival and sustain the transformative properties of cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 139.
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Wang J, Zhuang X, Greene KS, Si H, Antonyak MA, Druso JE, Wilson KF, Cerione RA, Feng Q, Wang H. Cdc42 functions as a regulatory node for tumour-derived microvesicle biogenesis. J Extracell Vesicles 2021; 10:e12051. [PMID: 33473262 PMCID: PMC7804048 DOI: 10.1002/jev2.12051] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 11/30/2020] [Accepted: 12/10/2020] [Indexed: 12/20/2022] Open
Abstract
Tumour-derived microvesicles (MVs) serve as critical mediators of cell-to-cell communication in the tumour microenvironment. So far, the underlying mechanisms of MV biogenesis, especially how key tumorigenesis signals such as abnormal EGF signalling regulates MV release, remain unclear. Here, we set out to establish reliable readouts for MV biogenesis and then explore the molecular mechanisms that regulate MV generation. We found that Rho family small G protein Cdc42 is a convergent node of multiple regulatory signals that occur in MV biogenesis. The binding of activated GTP-bound Cdc42 and its downstream effector, Ras GTPase-activating-like protein 1 (IQGAP1), is required for MV shedding. Activated Cdc42 maintains sustained EGF signalling by inhibiting the internalization of cell surface receptors, including EGFR and the VEGF oligomer, VEGF90K, and then facilitates MV release. Subsequently, we further demonstrated that blocking these signalling pathways using the corresponding mutants effectively reduced MV shedding and significantly inhibited MV-promoted in vivo tumour angiogenesis. These findings reveal a complex regulation of MV shedding by tumour cells, shedding light on the regulatory mechanism of MV biogenesis, and potentially contributing to strategies that target MVs in cancer therapy.
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Affiliation(s)
- Jing Wang
- Cancer Research Center The First Affiliated Hospital of USTC Division of Life Sciences and Medicine University of Science and Technology of China Hefei Anhui China.,National Center for Liver Cancer Eastern Hepatobiliary Surgery Hospital/Institute the Second Military Medical University Shanghai China
| | - Xiangjin Zhuang
- Cancer Research Center The First Affiliated Hospital of USTC Division of Life Sciences and Medicine University of Science and Technology of China Hefei Anhui China.,National Center for Liver Cancer Eastern Hepatobiliary Surgery Hospital/Institute the Second Military Medical University Shanghai China
| | - Kai Su Greene
- Department of Molecular Medicine Cornell University Ithaca New York USA
| | - Ha Si
- National Center for Liver Cancer Eastern Hepatobiliary Surgery Hospital/Institute the Second Military Medical University Shanghai China.,Affiliated Hospital of Inner Mongolia University for the Nationalities Tongliao Inner Mongolia China
| | - Marc A Antonyak
- Department of Molecular Medicine Cornell University Ithaca New York USA
| | - Joseph E Druso
- Department of Molecular Medicine Cornell University Ithaca New York USA
| | - Kristin F Wilson
- Department of Molecular Medicine Cornell University Ithaca New York USA
| | - Richard A Cerione
- Department of Molecular Medicine Cornell University Ithaca New York USA.,Department of Chemistry and Chemical Biology Cornell University Ithaca New York USA
| | - Qiyu Feng
- Cancer Research Center The First Affiliated Hospital of USTC Division of Life Sciences and Medicine University of Science and Technology of China Hefei Anhui China.,National Center for Liver Cancer Eastern Hepatobiliary Surgery Hospital/Institute the Second Military Medical University Shanghai China
| | - Hongyang Wang
- Cancer Research Center The First Affiliated Hospital of USTC Division of Life Sciences and Medicine University of Science and Technology of China Hefei Anhui China.,National Center for Liver Cancer Eastern Hepatobiliary Surgery Hospital/Institute the Second Military Medical University Shanghai China
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5
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Pumar OYT, Wilson KF, Cerione RA. Abstract 1447: Elucidating the mechanism of Dock7-mediated cellular transformation. Cancer Res 2020. [DOI: 10.1158/1538-7445.am2020-1447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Akt is a serine/threonine protein kinase that receives signals from a plethora of external and internal stimuli in order to promote survival and regulate cellular growth and metabolism. Akt is part of the highly conserved PI3K/Akt signaling axis and is classically regulated by its interaction with the phosphoinositide, PIP3, and its subsequent phosphorylation at S473 and S308 by the mTOR complex 2 (mTORC2) and 3-Phosphoinositide-dependent protein kinase 1 (PDK1), respectively. Altered Akt activity has been linked to numerous diseases, such as cancer, diabetes and neurodegenerative diseases. Specifically, PI3K/Akt deregulation occurs in approximately one third of human cancers and ~40% of breast cancers.
My research focuses on Dock7, a Guanine Nucleotide Exchange Factor (GEF) for the small GTPases Cdc42 and Rac1, and a novel player in the regulation of Akt activity and stability. Dock7 belongs to the Dock family of atypical GEFs and contains two evolutionarily conserved domains, DHR1 (a putative lipid binding domain) and DHR2 (the catalytic GEF domain). The expression level of Dock7 correlates with an unfavorable prognosis in liver cancer patients, and it is highly expressed in triple-negative breast cancers. Studies in our laboratory showed Dock7 is essential for the transformed properties of several cancer cell lines, and that it interacts with Akt in co-immunoprecipitation assays. In order to decipher the mechanism by which Dock7 mediates transformation, I created a Crispr-Cas9 Dock7 Knock-out HeLa cell line. I proceeded to confirm that these cells are not able to grow in an anchorage independent manner nor in serum free conditions, two hallmarks of transformation. Furthermore, in comparison to the phosphorylation status of Akt in parental HeLa cells, I found that in Dock7 KO HeLa cells, Akt is not phosphorylated at the S473 site in the absence of growth factors, indicative of lower basal activity. Accordingly, phosphorylation of downstream effectors of Akt is also downregulated. Besides promoting the phosphorylation state of Akt, Dock7 plays a role in the stability of the Akt protein during certain cellular stresses, highlighting a versatile and important role for Dock7 in Akt regulation and a potential target for therapeutic intervention in tumors where Akt is deregulated.
Citation Format: Oriana Y. Teran Pumar, Kristin F. Wilson, Richard A. Cerione. Elucidating the mechanism of Dock7-mediated cellular transformation [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1447.
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Affiliation(s)
- Kelly E Sullivan
- Department of Molecular Medicine, Cornell University, Ithaca, NY 82071, USA
| | - Richard A Cerione
- Department of Molecular Medicine, Cornell University, Ithaca, NY 82071, USA.,Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 82071, USA
| | - Kristin F Wilson
- Department of Molecular Medicine, Cornell University, Ithaca, NY 82071, USA
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7
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Sullivan KE, Rojas K, Cerione RA, Nakano I, Wilson KF. The stem cell/cancer stem cell marker ALDH1A3 regulates the expression of the survival factor tissue transglutaminase, in mesenchymal glioma stem cells. Oncotarget 2017; 8:22325-22343. [PMID: 28423611 PMCID: PMC5410226 DOI: 10.18632/oncotarget.16479] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 03/13/2017] [Indexed: 12/15/2022] Open
Abstract
Tissue transglutaminase (tTG), a dual-function enzyme with GTP-binding and acyltransferase activities, has been implicated in the survival and chemotherapy resistance of aggressive cancer cells and cancer stem cells, including glioma stem cells (GSCs). Using a model system comprising two distinct subtypes of GSCs referred to as proneural (PN) and mesenchymal (MES), we find that the phenotypically aggressive and radiation therapy-resistant MES GSCs exclusively express tTG relative to PN GSCs. As such, the self-renewal, proliferation, and survival of these cells was sensitive to treatment with tTG inhibitors, with a benefit being observed when combined with the standard of care for high grade gliomas (i.e. radiation or temozolomide). Efforts to understand the molecular drivers of tTG expression in MES GSCs revealed an unexpected link between tTG and a common marker for stem cells and cancer stem cells, Aldehyde dehydrogenase 1A3 (ALDH1A3). ALDH1A3, as well as other members of the ALDH1 subfamily, can function in cells as a retinaldehyde dehydrogenase to generate retinoic acid (RA) from retinal. We show that the enzymatic activity of ALDH1A3 and its product, RA, are necessary for the observed expression of tTG in MES GSCs. Additionally, the ectopic expression of ALDH1A3 in PN GSCs is sufficient to induce the expression of tTG in these cells, further demonstrating a causal link between ALDH1A3 and tTG. Together, these findings ascribe a novel function for ALDH1A3 in an aggressive GSC phenotype via the up-regulation of tTG, and suggest the potential for a similar role by ALDH1 family members across cancer types.
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Affiliation(s)
- Kelly E Sullivan
- Department of Molecular Medicine, Cornell University, Ithaca, NY, USA
| | - Kathy Rojas
- Department of Molecular Medicine, Cornell University, Ithaca, NY, USA
| | - Richard A Cerione
- Department of Molecular Medicine, Cornell University, Ithaca, NY, USA.,Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | - Ichiro Nakano
- Department of Neurosurgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Kristin F Wilson
- Department of Molecular Medicine, Cornell University, Ithaca, NY, USA
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8
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Lukey MJ, Greene KS, Erickson JW, Wilson KF, Cerione RA. The oncogenic transcription factor c-Jun regulates glutaminase expression and sensitizes cells to glutaminase-targeted therapy. Nat Commun 2016; 7:11321. [PMID: 27089238 PMCID: PMC4837472 DOI: 10.1038/ncomms11321] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 03/14/2016] [Indexed: 01/26/2023] Open
Abstract
Many transformed cells exhibit altered glucose metabolism and increased utilization of glutamine for anabolic and bioenergetic processes. These metabolic adaptations, which accompany tumorigenesis, are driven by oncogenic signals. Here we report that the transcription factor c-Jun, product of the proto-oncogene JUN, is a key regulator of mitochondrial glutaminase (GLS) levels. Activation of c-Jun downstream of oncogenic Rho GTPase signalling leads to elevated GLS gene expression and glutaminase activity. In human breast cancer cells, GLS protein levels and sensitivity to GLS inhibition correlate strongly with c-Jun levels. We show that c-Jun directly binds to the GLS promoter region, and is sufficient to increase gene expression. Furthermore, ectopic overexpression of c-Jun renders breast cancer cells dependent on GLS activity. These findings reveal a role for c-Jun as a driver of cancer cell metabolic reprogramming, and suggest that cancers overexpressing JUN may be especially sensitive to GLS-targeted therapies. Cancer cells have previously been shown to be addicted to glutamine and glutaminase enzyme activity. Here, the authors show that overexpression of the JUN proto-oncogene in breast cancer cells regulates glutaminase expression and is sufficient to confer sensitivity to glutaminase-targeted therapy.
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Affiliation(s)
- Michael J Lukey
- Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA
| | - Kai Su Greene
- Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA
| | - Jon W Erickson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Kristin F Wilson
- Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA
| | - Richard A Cerione
- Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA.,Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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9
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Abstract
UNLABELLED Overexpression of the receptor tyrosine kinase HER2/ErbB2 (ERBB2) has been linked to a poor prognosis for patients with breast cancer; thus, its activity is a central target for cancer therapy. Likewise, overexpression of heregulin (HRG/NRG1), a growth factor responsible for ErbB2 activation, has also been shown to be a driver of breast cancer progression. Although ErbB2 inhibitors offer a major advancement in the treatment of ErbB2-dependent breast cancers, patients are highly susceptible to developing clinical resistance to these drugs. Therefore, a detailed understanding of the molecular mechanism that underlies HRG/ErbB2-induced tumorigenesis is essential for the development of effective therapeutic strategies for this subset of patients with breast cancer. Here, it was demonstrated that HRG promoted anchorage-independent breast cancer cell growth more potently than EGF, and that the HRG-dependent activation of phosphoinositide 3-kinase and mTORC1 are necessary events for cell transformation. Functional evaluation of two distinct mTOR (MTOR) inhibitors, rapamycin and INK-128, on HRG-dependent signaling activities, uncovered a necessary role for mTORC2 in the regulation of the AKT/TSC2/mTORC1 axis by affecting the phosphorylation of AKT at the PDK1(PDPK1)-dependent site (T308) as well as at the mTORC2-dependent site (S473). The elimination of Rictor (RICTOR), a critical component of mTORC2, is detrimental to both the activation of mTORC1 and HRG-mediated cellular transformation. Similar results were obtained in multiple breast cancer model systems, highlighting an important role for mTORC2 in HRG/ErbB2-dependent breast cancer. IMPLICATIONS These findings suggest the potential benefits of targeting mTORC2 in HRG/ErbB2-induced breast cancer.
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Affiliation(s)
- Miao-chong J Lin
- Authors' Affiliation: Department of Molecular Medicine, Cornell University, Ithaca, New York
| | - Katherine S Rojas
- Authors' Affiliation: Department of Molecular Medicine, Cornell University, Ithaca, New York
| | - Richard A Cerione
- Authors' Affiliation: Department of Molecular Medicine, Cornell University, Ithaca, New York
| | - Kristin F Wilson
- Authors' Affiliation: Department of Molecular Medicine, Cornell University, Ithaca, New York
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10
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Wilson KF, Erickson JW, Antonyak MA, Cerione RA. Rho GTPases and their roles in cancer metabolism. Trends Mol Med 2012; 19:74-82. [PMID: 23219172 DOI: 10.1016/j.molmed.2012.10.011] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 10/16/2012] [Accepted: 10/24/2012] [Indexed: 12/14/2022]
Abstract
Recently, the small molecule 968 was found to block the Rho GTPase-dependent growth of cancer cells in cell culture and mouse xenografts, and when the target of 968 was found to be the mitochondrial enzyme glutaminase (GLS1), it revealed a surprising link between Rho GTPases and mitochondrial glutamine metabolism. Signal transduction via the Rho GTPases, together with NF-κB, appears to elevate mitochondrial glutaminase activity in cancer cells, thereby helping cancer cells satisfy their altered metabolic demands. Here, we review what is known about the mechanism of glutaminase activation in cancer cells, compare the properties of two distinct glutaminase inhibitors, and discuss recent findings that shed new light on how glutamine metabolism might affect cancer progression.
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Affiliation(s)
- Kristin F Wilson
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853-6401, USA
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11
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Abstract
A novel form of cell-to-cell communication involving the formation and shedding of large vesicular structures, called microvesicles (MVs), from the surfaces of highly aggressive forms of human cancer cells has been attracting increasing amounts of attention. This is in large part due to the fact that MVs contain a variety of cargo that is not typically thought to be released from cells including cell-surface receptor tyrosine kinases, cytosolic and nuclear signaling proteins and RNA transcripts. MVs, by sharing their contents with other cells, can greatly impact cancer progression by increasing primary tumor growth,1–3 as well as by promoting the development of the pre-metastatic niche.4 We have recently shown that the small GTPase RhoA is critical for MV biogenesis in human cancer cells. Moreover, we have now obtained evidence that implicates the highly related small GTPases, Rac and Cdc42, in regulating the loading of specific cargo into MVs, as well as in the shedding of MVs from cancer cells. Thus, linking the Rho family of small GTPases to MV biogenesis has begun to shed some light on a new and unexpected way that these signaling proteins contribute to human cancer progression.
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Affiliation(s)
- Marc A Antonyak
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
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12
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Wang JB, Erickson JW, Fuji R, Ramachandran S, Gao P, Dinavahi R, Wilson KF, Ambrosio ALB, Dias SMG, Dang CV, Cerione RA. Targeting mitochondrial glutaminase activity inhibits oncogenic transformation. Cancer Cell 2010; 18:207-19. [PMID: 20832749 PMCID: PMC3078749 DOI: 10.1016/j.ccr.2010.08.009] [Citation(s) in RCA: 632] [Impact Index Per Article: 45.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 04/20/2010] [Accepted: 07/19/2010] [Indexed: 12/18/2022]
Abstract
Rho GTPases impact a number of activities important for oncogenesis. We describe a small molecule inhibitor that blocks oncogenic transformation induced by various Rho GTPases in fibroblasts, and the growth of human breast cancer and B lymphoma cells, without affecting normal cells. We identify the target of this inhibitor to be the metabolic enzyme glutaminase, which catalyzes the hydrolysis of glutamine to glutamate. We show that transformed fibroblasts and breast cancer cells exhibit elevated glutaminase activity that is dependent on Rho GTPases and NF-κB activity, and is blocked by the small molecule inhibitor. These findings highlight a previously unappreciated connection between Rho GTPase activation and cellular metabolism and demonstrate that targeting glutaminase activity can inhibit oncogenic transformation.
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Affiliation(s)
- Jian-Bin Wang
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Jon W. Erickson
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Reina Fuji
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Sekar Ramachandran
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Ping Gao
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ramani Dinavahi
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Kristin F. Wilson
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | | | - Sandra M. G. Dias
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Chi V. Dang
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Richard A. Cerione
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
- Contact: , 607-253-3888 (tel), 607-253-3659 (fax)
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14
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Ly TK, Wang J, Pereira R, Rojas KS, Peng X, Feng Q, Cerione RA, Wilson KF. Activation of the Ran GTPase is subject to growth factor regulation and can give rise to cellular transformation. J Biol Chem 2009; 285:5815-26. [PMID: 20028979 DOI: 10.1074/jbc.m109.071886] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although the small GTPase Ran is best known for its roles in nucleocytoplasmic transport, mitotic spindle assembly, and nuclear envelope formation, recent studies have demonstrated the overexpression of Ran in multiple tumor types and that its expression is correlated with a poor patient prognosis, providing evidence for the importance of this GTPase in cell growth regulation. Here we show that Ran is subject to growth factor regulation by demonstrating that it is activated in a serum-dependent manner in human breast cancer cells and, in particular, in response to heregulin, a growth factor that activates the Neu/ErbB2 tyrosine kinase. The heregulin-dependent activation of Ran requires mTOR (mammalian target of rapamycin) and stimulates the capped RNA binding capability of the cap-binding complex in the nucleus, thus influencing gene expression at the level of mRNA processing. We further demonstrate that the excessive activation of Ran has important consequences for cell growth by showing that a novel, activated Ran mutant is sufficient to transform NIH-3T3 cells in an mTOR- and epidermal growth factor receptor-dependent manner and that Ran-transformed cells form tumors in mice.
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Affiliation(s)
- Thi K Ly
- Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA
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15
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Abstract
The nuclear cap-binding complex (CBC), a heterodimer comprised of a 20 kDa subunit (CBP20) and an 80 kDa regulatory subunit (CBP80), binds to nascent RNA polymerase II transcripts and is important throughout different aspects of RNA metabolism. In a recent publication, using a combination of X-ray crystallographic information, mutagenesis studies, small-angle scattering experiments, analytical ultracentrifugation and in vivo assays, we presented evidence that importin-α and importin-β, two nucleocytoplasmic transport proteins, play key roles in regulating the binding of capped RNA by the CBC in cells. A model for how complexes between CBC and the importins cycle in and out of the nucleus and direct the proper positional binding and release of capped RNA is presented here and is discussed in light of recent publications.
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Affiliation(s)
- Sandra Mg Dias
- Department of Molecular Medicine, College of Veterinary Medicine, Ithaca, NY, USA
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Abstract
The effect of an exogenous phytase and cellulase-containing enzyme formulation on nutrient digestibility and excretion was evaluated in 24 Holstein cows. Cows were fed corn silage- and alfalfa silage-based diets with or without a cellulase-phytase blend for 31 d in a continuous random design. Treatment groups were balanced for parity, days in milk, and mature-equivalent projected milk yield. Diets contained 37% forage, 18.3% crude protein, 35.4% neutral detergent fiber, 18% acid detergent fiber, and 0.42% P (no supplemental P). Cows were fed once daily in Calan doors and milked 2 times daily. Body weight and milk yield were recorded at each milking. Milk samples were collected on d 28 to 31 at 8 consecutive milkings. On d 28 to 31, fecal grab samples were collected every 8 h, with sampling times advanced by 2 h each day. Feces samples were pooled by cow. Feed and feces samples were analyzed for acid detergent lignin (used as an internal marker) and for N, P, neutral detergent fiber, and acid detergent fiber. Days in milk were similar between treatments, and body weight and milk yield were unaffected by treatment. Cows fed the enzyme formulation had reduced fecal dry matter, neutral detergent fiber, and acid detergent fiber excretion and reduced fecal excretion of N and P. Apparent digestibility of dry matter, acid detergent fiber, neutral detergent fiber, and N tended to increase with the enzyme formulation. Addition of an exogenous phytase and cellulase enzyme formulation to diets for lactating cows reduced fecal nutrient excretion.
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Affiliation(s)
- K F Knowlton
- Virginia Polytechnic Institute and State University, Blacksburg 24061, USA.
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17
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Calero G, Wilson KF, Ly T, Rios-Steiner JL, Clardy JC, Cerione RA. Structural basis of m7GpppG binding to the nuclear cap-binding protein complex. Nat Struct Biol 2002; 9:912-7. [PMID: 12434151 DOI: 10.1038/nsb874] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2002] [Accepted: 10/21/2002] [Indexed: 11/09/2022]
Abstract
The 7-methyl guanosine cap structure of RNA is essential for key aspects of RNA processing, including pre-mRNA splicing, 3' end formation, U snRNA transport, nonsense-mediated decay and translation. Two cap-binding proteins mediate these effects: cytosolic eIF-4E and nuclear cap-binding protein complex (CBC). The latter consists of a CBP20 subunit, which binds the cap, and a CBP80 subunit, which ensures high-affinity cap binding. Here we report the 2.1 A resolution structure of human CBC with the cap analog m7GpppG, as well as the structure of unliganded CBC. Comparisons between these structures indicate that the cap induces substantial conformational changes within the N-terminal loop of CBP20, enabling Tyr 20 to join Tyr 43 in pi-pi stacking interactions with the methylated guanosine base. CBP80 stabilizes the movement of the N-terminal loop of CBP20 and locks the CBC into a high affinity cap-binding state. The structure for the CBC bound to m7GpppG highlights interesting similarities and differences between CBC and eIF-4E, and provides insights into the regulatory mechanisms used by growth factors and other extracellular stimuli to influence the cap-binding state of the CBC.
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Affiliation(s)
- Guillermo Calero
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA
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18
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Abstract
Cdc42 is a low molecular weight GTP-binding protein that plays a key regulatory role in a variety of cellular activities. The importance of the coordination of different cell functions by Cdc42 is underscored by the fact that a constitutively active Cdc42 mutant induces cellular transformation. In this study, we describe a novel function for Cdc42: its ability to stimulate pre-messenger RNA splicing. This activity is dependent on cysteine 37 in the effector loop of Cdc42 but is not dependent on cell growth. A likely candidate protein for mediating the Cdc42 effects on pre-mRNA splicing is the nuclear RNA cap-binding complex (CBC), which plays a key role in an early step of cap-dependent RNA splicing. Activation of the CBC by Cdc42 can be inhibited by rapamycin. Additionally, phosphatidylinositol 3-kinase and the Cdc42 effector, pp70 S6 kinase, stimulate the RNA cap-binding activity of the CBC. S6 kinase may directly target the CBC in vivo as it can phosphorylate the 80-kDa subunit of the CBC, CBP80, at residues that are subject to a growth factor-dependent and rapamycin-sensitive phosphorylation in vivo. Together these data suggest the involvement of a Cdc42-S6 kinase pathway in the regulation of RNA splicing, mediated by an increase in capped RNA binding by the CBC, as well as raise the possibility that the effects of Cdc42 on cell growth may be due in part to its regulation of RNA processing.
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Affiliation(s)
- K F Wilson
- Departments of Molecular Medicine and Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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19
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Abstract
Traditionally, growth factor-coupled signaling to the nucleus has been thought to be primarily directed toward transcriptional regulation. However, there are now increasing indications from a diversity of experimental systems that other aspects of RNA processing, including translation, lifetime and stability, and splicing are under strict growth factor control. In this review, we present the emerging evidence for growth factor signaling pathways that impact on these different RNA processing events. Particularly noteworthy is the realization that growth factor signaling through Ras can effect the regulation of two RNA cap-binding proteins, the cytosolic eIF-4E complex, which is necessary for initiating translation, and the nuclear cap-binding complex, the CBC, which plays a role in cap-dependent pre-mRNA splicing, U snRNA export and 3'-end processing. This, taken together with other findings that demonstrate the ability of stress response pathways and the small G protein, Cdc42, to activate the CBC, raises some interesting possibilities regarding how signaling to the two cellular RNA cap-binding protein complexes may coordinate the growth-coupled regulation of gene expression at the level of RNA processing.
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Affiliation(s)
- K F Wilson
- Department of Molecular Medicine, Cornell University, Ithaca, NY, USA
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20
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Wilson KF, Fortes P, Singh US, Ohno M, Mattaj IW, Cerione RA. The nuclear cap-binding complex is a novel target of growth factor receptor-coupled signal transduction. J Biol Chem 1999; 274:4166-73. [PMID: 9933612 DOI: 10.1074/jbc.274.7.4166] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In an attempt to further understand how nuclear events (such as gene expression, nuclear import/export, and cell cycle checkpoint control) might be subject to regulation by extracellular stimuli, we sought to identify nuclear activities under growth factor control. Using a sensitive photoaffinity labeling assay that measured [alpha-32P]GTP incorporation into nuclear proteins, we identified the 20-kDa subunit of the nuclear cap-binding complex (CBC) as a protein whose binding activity is greatly enhanced by the extracellular stimulation of serum-arrested cells. The CBC represents a 20- and 80-kDa heterodimer (the subunits independently referred to as CBP20 and CBP80, respectively) that binds the 7-methylguanosine cap on RNAs transcribed by RNA polymerase II. This binding facilitates precursor messenger RNA splicing and export. We have demonstrated that the [alpha-32P]GTP incorporation into CBP20 was correlated with an increased ability of the CBC to bind capped RNA and have used the [alpha-32P]GTP photoaffinity assay to characterize the activation of the CBC in response to growth factors. We show that the CBC is activated by heregulin in HeLa cells and by nerve growth factor in PC12 cells as well as during the G1/S phase of the cell cycle and when cells are stressed with UV irradiation. Additionally, we show that cap-dependent splicing of precursor mRNA, a functional outcome of CBC activation, can be catalyzed by growth factor addition to serum-arrested cells. Taken together, these data identify the CBC as a nuclear target for growth factor-coupled signal transduction and suggest novel mechanisms by which growth factors can influence gene expression and cell growth.
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Affiliation(s)
- K F Wilson
- Department of Biochemistry, Molecular and Cellular Biology, Cornell University, Ithaca, New York 14853, USA
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21
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Wilson KF, Fielder PJ, Guevara-Aguirre J, Cohen P, Vasconez O, Martinez V, Martinez A, Rosenbloom AL, Rosenfeld RG. Long-term effects of insulin-like growth factor (IGF)-I treatment on serum IGFs and IGF binding proteins in adolescent patients with growth hormone receptor deficiency. Clin Endocrinol (Oxf) 1995; 42:399-407. [PMID: 7538453 DOI: 10.1111/j.1365-2265.1995.tb02649.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVE The aim of this investigation was to study the effect of relatively high dose IGF-I therapy given for several months, on serum levels of IGF-I, IGF-II and IGFBP-3, and on IGF-I pharmacokinetics in patients with growth hormone insensitivity due to GH receptor dysfunction. DESIGN AND PATIENTS Two adolescent subjects from Ecuador were treated with recombinant IGF-I at a dosage of 120 micrograms/kg s.c. twice daily, in combination with a GnRH analogue for 8 months. MEASUREMENTS Serum was sampled at baseline and at 3-8 months, for determination of IGF-I, IGF-II and IGFBP-3 by radioimmunoassay, and for evaluation of IGFBPs and IGFBP-3 protease activity by Western ligand blot and protease assay, respectively. RESULTS Peak serum IGF-I levels ranged from 272 to 492 micrograms/l. Mean serum IGF-II levels were decreased concurrently with the increase in IGF-I. Serum IGFBP-3 levels failed to rise with prolonged IGF-I treatment. There was no apparent change in the half-life of IGF-I during the treatment period. CONCLUSIONS IGF-I administration does not increase serum levels of IGFBP-3 or significantly alter IGF-I pharmacokinetics.
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Affiliation(s)
- K F Wilson
- Department of Pediatrics, Stanford University Medical School, CA, USA
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22
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Müller HL, Oh Y, Gargosky SE, Wilson KF, Lehrnbecher T, Rosenfeld RG. Insulin-like growth factor binding protein-3 concentrations and insulin-like growth factor binding protein-3 protease activity in sera of patients with malignant solid tumors or leukemia. Pediatr Res 1994; 35:720-4. [PMID: 7524013 DOI: 10.1203/00006450-199406000-00019] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
IGF binding proteins (IGFBP) regulate the bioavailability and bioactivity of IGF. The major IGFBP in serum is IGFBP-3. We investigated whether sera from children with malignancies show alterations in levels of IGFBP-3 as measured by Western ligand blot analysis (WLB) and RIA with alpha IGFBP-3gl, a specific rabbit polyclonal antibody. Furthermore, IGFBP-3 proteolysis was quantified by densitometric analysis of [125I]IGFBP-3 protease assays, and IGFBP-3 fragments were visualized by Western immunoblot with alpha IGFBP-3gl. We examined sera from 21 children with solid tumors, five patients with sarcoma who had reached complete remission, and 13 children with acute leukemia. Serum samples were collected at diagnosis, before initiation of therapy. Sera of 10 healthy children served as normal controls. Children with solid tumor or leukemia had significantly higher (p < 0.001) IGFBP-3 protease activity in serum than did normal controls or patients with sarcoma in complete remission. Corresponding to this finding, densitometry of WLB showed lower IGFBP-3 levels in sera of children with malignancies in comparison with normal controls. The negative correlation (p < 0.001, r = -0.80) between IGFBP-3 proteolysis, as measured by [125I]IGFBP-3 protease assay, and IGFBP-3 band density on WLB indicates that proteolysis is the probable reason for reduction of IGFBP-3 on WLB. IGFBP-3 concentrations measured by RIA were in the normal range for most patients, further indicating that differences in serum IGFBP-3 levels measured by WLB reflect protease activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H L Müller
- Department of Pediatrics, Stanford University School of Medicine, SUMC, California 94305
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23
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Gargosky SE, Wilson KF, Fielder PJ, Vaccarello MA, Diamond FB, Baxter RC, Rosenbloom AL, Guevara-Aguirre J, Rosenfeld RG. Effects of insulin-like growth factor I treatment on the molecular distribution of insulin-like growth factors among different binding proteins. Acta Paediatr Suppl 1994; 399:159-62. [PMID: 7524822 DOI: 10.1111/j.1651-2227.1994.tb13316.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The molecular distribution of insulin-like growth factor I (IGF-I) and IGF-II among the IGF binding proteins (IGFBPs) was studied before and during IGF-I therapy in Ecuadorean adults with growth hormone receptor deficiency (GHRD). Of the total circulating IGF-I and IGF-II, 70% was carried by the 150 kDa complex in normal subjects, while in patients with GHRD, 50% of serum IGF-I, but only 30-35% of serum IGF-II, was measured within the 150 kDa IGFBP-3 region. Administration of IGF-I altered the concentration of IGF-I and IGF-II, although the percentage of total IGF measured within each IGFBP region was not affected, as the increase in IGF-I and the decrease in IGF-II were proportional. Similarly, serum concentrations of IGFBP-3 and the acid-labile subunit, measured by radioimmunoassay, were unaltered. Thus, administration of IGF-I to patients with GHRD was unable to correct the aberrant distribution of IGFs among the IGFBPs.
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Affiliation(s)
- S E Gargosky
- Department of Pediatrics, Stanford University School of Medicine, California
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24
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Gargosky SE, Wilson KF, Fielder PJ, Vaccarello MA, Guevara-Aguirre J, Diamond FB, Baxter RC, Rosenbloom AL, Rosenfeld RG. The composition and distribution of insulin-like growth factors (IGFs) and IGF-binding proteins (IGFBPs) in the serum of growth hormone receptor-deficient patients: effects of IGF-I therapy on IGFBP-3. J Clin Endocrinol Metab 1993; 77:1683-9. [PMID: 7505289 DOI: 10.1210/jcem.77.6.7505289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We have previously reported that adult GH receptor-deficient (GHRD) patients treated subcutaneously with recombinant human insulin-like growth factor (IGF)-I have increased serum IGF-I levels and decreased IGF-II levels, whereas IGF-binding protein-3 (IGFBP-3) levels were unchanged. To further investigate the effects of IGF-I administration upon the IGF-IGFBP axis in GHRD, we have examined: 1) the molecular distribution of IGF-I and IGF-II among the IGFBPs; 2) the composition and distribution of the IGFBPs, in particular IGFBP-3; and 3) the acid labile subunit (ALS). Serum samples from adult GHRD patients who were treated sc with recombinant human IGF-I (40 micrograms/kg, sc, twice a day) or from normal Ecuadorian adults were incubated with [125I]IGF-II and subjected to neutral size-exclusion chromatography. The fractions were then subjected to Western ligand blot, Western immunoblot, IGFBP-3 RIA, and IGF RIAs. Serum of healthy adults incorporated [125I]IGF-II into the 150- and 44-kilodalton (kDa) IGFBP region. The 150-kDa IGFBP region contained most of the circulating IGFBP-3, whereas the 44-kDa IGFBP region contained mainly IGFBP-1, 2, and 4. The 150-kDa region also contained a unique 28-kDa immunoreactive form of IGFBP-3, which was not detectable by Western ligand blot. Endogenous IGF-I and IGF-II were distributed equally in the 150- and 44-kDa IGFBP regions. Sera from GHRD patients mainly incorporated [125I]IGF-II into the 44-kDa IGFBP region. Similar to control sera, the 150-kDa IGFBP region contained IGFBP-3, albeit at lower concentrations. The 44-kDa IGFBP region contained all IGFBPs including 50% of the total immunoreactive IGFBP-3. The two immunoreactive forms of IGFBP 3 (40- to 45-kDa doublet and 28-kDa band) were present in both IGFBP regions. The IGF size-distribution study revealed that the 150-kDa IGFBP region carried half of the circulating endogenous IGF-I, but only 30% of the IGF-II. Concentrations of the ALS were consistently low. Administration of IGF-I to GHRD patients was unable to increase concentrations of the molecular forms of IGFBP-3, correct the aberrant distribution of IGFs among the IGFBPs, or increase serum concentrations of ALS. In conclusion, we have found two forms of IGFBP-3 associated with IGF and ALS, which are capable of forming the ternary 150-kDa complex in healthy adult serum. The ratio of these two forms of IGFBP-3 and their distribution in serum was different between GHRD and control patients.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- S E Gargosky
- Department of Pediatrics, Stanford University School of Medicine, California 94305
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25
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Fielder PJ, Tauber JP, Wilson KF, Pham HM, Rosenfeld RG. Insulin-like growth factors (IGFs) stimulate and dexamethasone inhibits IGF binding protein (BP)-5 expression in a mouse pituitary cell line. Growth Regul 1993; 3:226-34. [PMID: 7510565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The mouse pituitary cell line AtT-20 was found to secrete two low MW IGFBPs into conditioned medium (CM). The major IGFBP migrated at approximately 29 kDa and a minor IGFBP of 24 kDa was also present on western ligand blots (WLB). Both IGFBPs were purified from CM by IGF-affinity chromatography followed by reverse phase-FPLC. N-terminal analysis revealed that the first 10 amino acids of the 29 kDa and the 24 kDa IGFBPs were homologous to corresponding sequences of both human and rat IGFBP-5 and IGFBP-4, respectively. The 24 kDa IGFBP also crossreacted with a new antiserum specific for rodent IGFBP-4. The concentrations of both IGFBPs were increased by the addition of IGF-I, IGF-II, or insulin to the cell cultures, with IGFBP-5 demonstrating the greatest hormonal stimulation. The effects of IGF-I on IGFBP-5 expression were both time and dose dependent, with IGF-I being more potent than IGF-II, and IGF-II more potent than insulin. The relative potencies of these hormones in stimulating IGFBP-5 production were consistent with the peptides acting through the type-I IGF receptor. Similarly, the IGF-II analog [Leu 27]-IGF-II, which has very low affinity for the type-I receptor, only slightly stimulated an increase in IGFBP-5. Addition of dexamethasone to the cultures decreased both basal and IGF-stimulated IGFBP-5 production. Northern blotting demonstrated that IGF-I increased the expression of the mRNA for IGFBP-5, whereas dexamethasone decreased it. Together, these data suggest that the IGFs can increase IGFBP-5 production at both the protein and mRNA level.
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Affiliation(s)
- P J Fielder
- Department of Pediatrics, Stanford University Medical School, CA 94305
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26
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Cohen P, Peehl DM, Stamey TA, Wilson KF, Clemmons DR, Rosenfeld RG. Elevated levels of insulin-like growth factor-binding protein-2 in the serum of prostate cancer patients. J Clin Endocrinol Metab 1993; 76:1031-5. [PMID: 7682560 DOI: 10.1210/jcem.76.4.7682560] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We have previously documented the presence of specific insulin-like growth factor (IGF)-binding protein (IGFBPs) in seminal plasma and prostate epithelial cell-conditioned medium IGFBP-2 is the prevalent IGFBP in both fluids. To assess whether patients with prostate carcinoma have alterations in serum IGFP levels related to the production of IGFBPs by their tumors, we performed Western ligand blots (WLB) and IGFBP-2 RIA on serum samples from 32 patients with prostate carcinoma of various degrees of clinical severity and compared them to results in 16 healthy age-matched controls. We have also measured serum IGF-I and -II by RIA. The mean level of IGFBP-2 in the prostate cancer patients was 170% of control levels by WLB analysis and 195% of control levels by RIA (P < 0.01). The degree of elevation of IGFBP-2 was related to the stage of the tumor and the levels of the serum tumor marker, prostate-specific antigen. Serum IGFBP-3 levels determined by WLB and serum IGF-I and IGF-II levels measured by RIA after acid chromatography were not different among the subjects with cancer and the normal controls. We conclude that IGFBP-2, which is the main IGFBP produced by prostate epithelial cells, is elevated in the serum of patients with prostate carcinoma, and that the degree of this elevation is related to serum prostate-specific antigen levels and the stage of the tumor. We speculate that prostate-derived IGFBPs may be secreted by prostate tumors and could e of value in understanding the pathophysiology of prostatic tumor growth as well as provide potential diagnostic markers.
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Affiliation(s)
- P Cohen
- Department of Pediatrics, Stanford University Medical Center, California 94305
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27
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Lamson G, Giudice LC, Cohen P, Liu F, Gargosky S, Müller HL, Oh Y, Wilson KF, Hintz RL, Rosenfeld RG. Proteolysis of IGFBP-3 may be a common regulatory mechanism of IGF action in vivo. Growth Regul 1993; 3:91-5. [PMID: 7683546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- G Lamson
- Department of Pediatrics, Stanford University School of Medicine, CA
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28
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Rosenfeld RG, Gargosky SE, Pham HM, Wilson KF, Giudice LC. Comparative Use of Immunological Methods & Ligand Blotting of Insulin-like Growth Factor Binding Proteins in Serum and Other Biological Fluids. Clin Pediatr Endocrinol 1993. [DOI: 10.1297/cpe.2.supple2_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Ron G. Rosenfeld
- Departments of Pediatrics and, Obstetrics and Gynecology, Stanford University Medical School
| | - Sharron E. Gargosky
- Departments of Pediatrics and, Obstetrics and Gynecology, Stanford University Medical School
| | - Hung M. Pham
- Departments of Pediatrics and, Obstetrics and Gynecology, Stanford University Medical School
| | - Kristin F. Wilson
- Departments of Pediatrics and, Obstetrics and Gynecology, Stanford University Medical School
| | - Linda C. Giudice
- Departments of Pediatrics and, Obstetrics and Gynecology, Stanford University Medical School
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29
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Gargosky SE, Pham HM, Wilson KF, Liu F, Giudice LC, Rosenfeld RG. Measurement and characterization of insulin-like growth factor binding protein-3 in human biological fluids: discrepancies between radioimmunoassay and ligand blotting. Endocrinology 1992; 131:3051-60. [PMID: 1280211 DOI: 10.1210/endo.131.6.1280211] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The inability to detect insulin-like growth factor binding protein-3 (IGFBP-3) in some circumstances by Western ligand blot analysis has emphasized the need to characterize IGFBPs by both ligand binding and immunological techniques. In this study, we have: 1) characterized and quantified IGFBP-3 in nonpregnancy, pregnancy, and fetal cord serum, follicular, peritoneal, and amniotic fluid, seminal plasma, cerebrospinal fluid (CSF), and urine; 2) established a new IGFBP-3 RIA that detects both intact and fragments of IGFBP-3; 3) identified both intact and fragments of IGFBP-3 by Western immunoblot techniques; and 4) addressed the discordance between Western ligand blot analysis and RIA by assessing fluids for IGFBP proteolytic activity. All fluids examined, except pregnancy serum, CSF, and amniotic fluid, displayed a 44-34-kilodalton (kDa) IGFBP-3 doublet by Western ligand blot analysis. Western immunoblot analysis using specific IGFBP-3 antiserum showed a 44-34-kDa IGFBP-3 doublet and a 28-kDa fragment in nonpregnancy serum, fetal cord serum, follicular fluid, and peritoneal fluid. The immunoreactive 42-38-kDa doublet was faint in urine and seminal plasma. IGFBPs in CSF did not cross-react with IGFBP-3 antiserum. Pregnancy serum and amniotic fluid contained only the 28-kDa fragment when compared against equal volumes of nonpregnancy serum. With the development of an IGFBP-3 RIA, IGFBP-3 could be accurately measured; urine, CSF, and seminal plasma contained the lowest levels of IGFBP-3 at 27 +/- 3 ng/ml (mean +/- SEM), 110 +/- 26 ng/ml, and 209 +/- 56 ng/ml, respectively. In increasing concentration: fetal cord serum contained 753 +/- 101 ng/ml; peritoneal fluid, 1124 +/- 130 ng/ml; follicular fluid, 2356 +/- 211 ng/ml; nonpregnancy serum, 3556 +/- 508 ng/ml; pregnancy serum, 3718 +/- 842 ng/ml; and amniotic fluid, 5150 +/- 688 ng/ml. The measurable concentrations of IGFBP-3 in CSF and the high concentrations measured in pregnancy serum and amniotic fluid conflicted with Western blot analysis. Thus, fluids were assessed for IGFBP proteolytic activity by incubation with a source of IGFBP-3, either nonpregnancy serum or purified IGFBP-3. All fluids displayed some proteolytic activity with either assay. Fluids with little protease activity (nonpregnancy serum, follicular fluid, and urine) showed a close relationship between immunoassayable IGFBP-3 by RIA and IGFBP-3 band intensity by Western ligand blot. Fluids with high proteolytic activity (pregnancy serum, CSF, seminal plasma, peritoneal fluid, and amniotic fluid) gave discrepant IGFBP-3 values between RIA and Western ligand blot.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- S E Gargosky
- Department of Pediatrics, Stanford University School of Medicine, California 94305
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30
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Conley M, Wilson KF. Dendritic organization of class II (inter)neurons in the dorsal lateral geniculate nucleus of the tree shrew: observations based on Golgi, immunocytochemical, and biocytin methods. J Comp Neurol 1992; 319:51-65. [PMID: 1592905 DOI: 10.1002/cne.903190107] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In this report we examine the dendritic organization of putative interneurons (class II cells) in different layers of the dorsal lateral geniculate nucleus of the tree shrew. The results show that there is considerable morphological diversity within this class, but that two broad groups can be identified: neurons whose dendrites remain within a layer or its adjacent interlaminar zones (intralaminar class II cells); and neurons whose dendrites cross into an adjacent layer(s) (interlaminar class II cells). The majority of class II cells in every layer have intralaminar dendrites, some of which are oriented along a particular axis, and others that are organized radially. The paired layers (1 and 2, 4 and 5) contain a particular group of intralaminar class II cells that have radially organized dendrites and elaborate claw-like appendages. The dendrites of interlaminar class II cells are organized along lines of projection and extend across as many as four layers. These cells often reside close to or within the interlaminar zones. Overall, the organization of class II cells seems to follow a pattern similar to the class I (relay) cells identified previously. Most have intralaminar dendrites, which presumably underlie the fidelity of signals transmitted from the retina to a particular layer. However, there are also a number of other cells whose processes cross laminar borders, presumably to affect integrative functions within the nucleus.
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Affiliation(s)
- M Conley
- Department of Psychology, Duke University, Durham, North Carolina 27706
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