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Oyer HM, Steck AR, Longen CG, Venkat S, Bayrak K, Munger EB, Fu D, Castagnino PA, Sanders CM, Tancler NA, Mai MT, Myers JP, Schiewer MJ, Chen N, Mostaghel EA, Kim FJ. Sigma1 Regulates Lipid Droplet-mediated Redox Homeostasis Required for Prostate Cancer Proliferation. Cancer Res Commun 2023; 3:2195-2210. [PMID: 37874216 PMCID: PMC10615122 DOI: 10.1158/2767-9764.crc-22-0371] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 03/01/2023] [Accepted: 10/16/2023] [Indexed: 10/25/2023]
Abstract
Lipid droplets (LD) are dynamic organelles that serve as hubs of cellular metabolic processes. Emerging evidence shows that LDs also play a critical role in maintaining redox homeostasis and can mitigate lipid oxidative stress. In multiple cancers, including prostate cancer, LD accumulation is associated with cancer aggressiveness, therapy resistance, and poor clinical outcome. Prostate cancer arises as an androgen receptor (AR)-driven disease. Among its myriad roles, AR mediates the biosynthesis of LDs, induces autophagy, and modulates cellular oxidative stress in a tightly regulated cycle that promotes cell proliferation. The factors regulating the interplay of these metabolic processes downstream of AR remain unclear. Here, we show that Sigma1/SIGMAR1, a unique ligand-operated scaffolding protein, regulates LD metabolism in prostate cancer cells. Sigma1 inhibition triggers lipophagy, an LD selective form of autophagy, to prevent accumulation of LDs which normally act to sequester toxic levels of reactive oxygen species (ROS). This disrupts the interplay between LDs, autophagy, buffering of oxidative stress and redox homeostasis, and results in the suppression of cell proliferation in vitro and tumor growth in vivo. Consistent with these experimental results, SIGMAR1 transcripts are strongly associated with lipid metabolism and ROS pathways in prostate tumors. Altogether, these data reveal a novel, pharmacologically responsive role for Sigma1 in regulating the redox homeostasis required by oncogenic metabolic programs that drive prostate cancer proliferation. SIGNIFICANCE To proliferate, cancer cells must maintain productive metabolic and oxidative stress (eustress) while mitigating destructive, uncontrolled oxidative stress (distress). LDs are metabolic hubs that enable adaptive responses to promote eustress. Targeting the unique Sigma1 protein can trigger distress by disrupting the LD-mediated homeostasis required for proliferation.
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Affiliation(s)
- Halley M. Oyer
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
| | - Alexandra R. Steck
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
| | - Charles G. Longen
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
| | - Sanjana Venkat
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
| | - Konuralp Bayrak
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
| | - Eleanor B. Munger
- Department of Chemistry, University of Washington, Seattle, Washington
| | - Dan Fu
- Department of Chemistry, University of Washington, Seattle, Washington
| | - Paola A. Castagnino
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
| | - Christina M. Sanders
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
| | - Nathalia A. Tancler
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
| | - My T. Mai
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
| | - Justin P. Myers
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
| | - Matthew J. Schiewer
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
- Department of Urology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Nan Chen
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
| | - Elahe A. Mostaghel
- Department of Medicine, University of Washington, Seattle, Washington
- Geriatric Research, Education and Clinical Center, U.S. Department of Veterans Affairs Puget Sound Health Care System, Seattle, Washington
| | - Felix J. Kim
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center at Jefferson, Philadelphia, Pennsylvania
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Laszlo KJ, Buckner JH, Munger EB, Bush MF. Native-Like and Denatured Cytochrome c Ions Yield Cation-to-Anion Proton Transfer Reaction Products with Similar Collision Cross-Sections. J Am Soc Mass Spectrom 2017; 28:1382-1391. [PMID: 28224394 PMCID: PMC5555649 DOI: 10.1007/s13361-017-1620-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 01/28/2017] [Accepted: 01/30/2017] [Indexed: 05/04/2023]
Abstract
The relationship between structures of protein ions, their charge states, and their original structures prior to ionization remains challenging to decouple. Here, we use cation-to-anion proton transfer reactions (CAPTR) to reduce the charge states of cytochrome c ions in the gas phase, and ion mobility to probe their structures. Ions were formed using a new temperature-controlled nanoelectrospray ionization source at 25 °C. Characterization of this source demonstrates that the temperature of the liquid sample is decoupled from that of the atmospheric pressure interface, which is heated during CAPTR experiments. Ionization from denaturing conditions yields 18+ to 8+ ions, which were each isolated and reacted with monoanions to generate all CAPTR products with charge states of at least 3+. The highest, intermediate, and lowest charge-state products exhibit collision cross-section distributions that are unimodal, multimodal, and unimodal, respectively. These distributions depend strongly on the charge state of the product, although those for the intermediate charge-state products also depend on that of the precursor. The distributions of the 3+ products are all similar, with averages that are less than half that of the 18+ precursor ions. Ionization of cytochrome c from native-like conditions yields 7+ and 6+ ions. The 3+ CAPTR products from these precursors have slightly more compact collision cross-section distributions that are indistinguishable from those for the 3+ CAPTR products from denaturing conditions. More broadly, these results indicate that the collision cross-sections of ions of this single domain protein depend strongly on charge state for charge states greater than ~4. Graphical Abstract ᅟ.
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Affiliation(s)
- Kenneth J Laszlo
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - John H Buckner
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
- Department of Chemistry, Carleton College, One North College Street, Northfield, MN, 55057, USA
| | - Eleanor B Munger
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - Matthew F Bush
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA.
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Abstract
The fidelity between the structures of proteins in solution and protein ions in the gas phase is critical to experiments that use gas-phase measurements to infer structures in solution. Here we generate ions of lysozyme, a 129-residue protein whose native tertiary structure contains four internal disulfide bonds, from three solutions that preserve varying extents of the original native structure. We then use cation-to-anion proton-transfer reactions (CAPTR) to reduce the charge states of those ions in the gas phase and ion mobility to probe their structures. The collision cross section (Ω) distributions of each CAPTR product depends to varying extents on the original solution, the charge state of the product, and the charge state of the precursor. For example, the Ω distributions of the 6+ ions depend strongly on the original solutions conditions and to a lesser extent on the charge state of the precursor. Energy-dependent experiments suggest that very different structures are accessible to disulfide-reduced and disulfide-intact ions, but similar Ω distributions are formed at high energy for disulfide-intact ions from denaturing and from aqueous conditions. The Ω distributions of the 3+ ions are all similar but exhibit subtle differences that depend more strongly on the original solutions conditions than other factors. More generally, these results suggest that specific CAPTR products may be especially sensitive to specific elements of structure in solution.
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Affiliation(s)
- Kenneth J Laszlo
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Eleanor B Munger
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Matthew F Bush
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
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Abstract
The structure and folding of a protein in solution depends on noncovalent interactions within the protein and those with surrounding ions and molecules. Decoupling these interactions in solution is challenging, which has hindered the development of accurate physics-based models for structure prediction. Investigations of proteins in the gas phase can be used to selectively decouple factors affecting the structures of proteins. Here, we use cation-to-anion proton-transfer reactions (CAPTR) to reduce the charge states of denatured ubiquitin ions in the gas phase, and ion mobility to probe their structures. In CAPTR, a precursor charge state is selected (P) and reacted with monoanions to generate charge-reduced product ions (C). Following each CAPTR event, denatured ubiquitin ions (13+ to 6+) yield products that rapidly isomerize to structures that have smaller collision cross sections (Ω). The Ω values of CAPTR product ions depend strongly on C and very weakly on P. Pre- and post-CAPTR activation was then used to probe the potential-energy surfaces of the precursor and product ions, respectively. Post-CAPTR activation showed that ions of different P fold differently and populate different regions of the potential-energy surface of that ion. Finally, pre-CAPTR activation showed that the structures of protein ions can be indirectly investigated using ion mobility of their CAPTR product ions, even for subtle structural differences that are not apparent from ion mobility characterization of the activated precursor ions. More generally, these results show that CAPTR strongly complements existing techniques for characterizing the structures and dynamics of biological molecules in the gas phase.
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Affiliation(s)
- Kenneth J. Laszlo
- University of Washington, Department of Chemistry, Box 351700 Seattle, WA 98195-1700
| | - Eleanor B. Munger
- University of Washington, Department of Chemistry, Box 351700 Seattle, WA 98195-1700
| | - Matthew F. Bush
- University of Washington, Department of Chemistry, Box 351700 Seattle, WA 98195-1700
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