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Ding J, Kuo ML, Su L, Xue L, Luh F, Zhang H, Wang J, Lin TG, Zhang K, Chu P, Zheng S, Liu X, Yen Y. Human mitochondrial pyrroline-5-carboxylate reductase 1 promotes invasiveness and impacts survival in breast cancers. Carcinogenesis 2017; 38:519-531. [PMID: 28379297 DOI: 10.1093/carcin/bgx022] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 02/21/2017] [Indexed: 12/16/2023] Open
Abstract
Human mitochondrial pyrroline-5-carboxylate reductase (PYCR) is a house-keeping enzyme that catalyzes the reduction of Δ1-pyrroline-5-carboxylate to proline. This enzymatic cycle plays pivotal roles in amino acid metabolism, intracellular redox potential and mitochondrial integrity. Here, we hypothesize that PYCR1 might be a novel prognostic biomarker and therapeutic target for breast cancer. In this study, breast cancer tissue samples were obtained from Zhejiang University (ZJU set). Immunohistochemistry analysis was performed to detect the protein level of PYCR1, and Kaplan-Meier and Cox proportional analyses were employed in this outcome study. The prognostic significance and performance of PYCR1 mRNA were validated on 13 worldwide independent microarray data sets, composed of 2500 assessable breast cancer cases. Our findings revealed that both PYCR1 mRNA and protein expression were significantly associated with tumor size, grade and invasive molecular subtypes of breast cancers. Independent and pooled analyses verified that higher PYCR1 mRNA levels were significantly associated with poor survival of breast cancer patients, regardless of estrogen receptor (ER) status. For in vitro studies, inhibition of PYCR1 by small-hairpin RNA significantly reduced the growth and invasion capabilities of the cells, while enhancing the cytotoxicity of doxorubicin in breast cancer cell lines MCF-7 (ER positive) and MDA-MB-231 (ER negative). Further population study also validated that chemotherapy significantly improved survival in early-stage breast cancer patients with low PYCR1 expression levels. Therefore, PYCR1 might serve as a prognostic biomaker for either ER-positive or ER-negative breast cancer subtypes and can also be a potential target for breast cancer therapy.
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Affiliation(s)
- Jiefeng Ding
- Shaoxing Women and Children's Hospital, Shaoxing, Zhejiang 312000, China
- City of Hope National Medical Center, Duarte, CA 91010, USA
| | - Mei-Ling Kuo
- City of Hope National Medical Center, Duarte, CA 91010, USA
| | - Leila Su
- Ph.D. Program of Cancer Biology and Drug Discovery, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan, ROC
| | - Lijun Xue
- Pathology Department, Loma Linda University Medical Center, Loma Linda, CA 92354, USA
| | - Frank Luh
- General Medicine Division, College of Medicine, Taipei Medical University, Taipei 110, Taiwan, ROC
- Sino-American Cancer Foundation, 4978 Santa Anita Ave, Suite #104, Temple City, CA 91780, USA
| | - Hang Zhang
- Cancer Institute, Zhejiang University, Hangzhou, Zhejiang 310009, China and
| | - Jianghai Wang
- Sino-American Cancer Foundation, 4978 Santa Anita Ave, Suite #104, Temple City, CA 91780, USA
| | - Tiffany G Lin
- Sino-American Cancer Foundation, 4978 Santa Anita Ave, Suite #104, Temple City, CA 91780, USA
| | - Keqiang Zhang
- City of Hope National Medical Center, Duarte, CA 91010, USA
| | - Peiguo Chu
- City of Hope National Medical Center, Duarte, CA 91010, USA
| | - Shu Zheng
- Cancer Institute, Zhejiang University, Hangzhou, Zhejiang 310009, China and
| | - Xiyong Liu
- Ph.D. Program of Cancer Biology and Drug Discovery, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan, ROC
- Sino-American Cancer Foundation, 4978 Santa Anita Ave, Suite #104, Temple City, CA 91780, USA
- California Cancer Institute, Temple City, CA 91007, USA
| | - Yun Yen
- Ph.D. Program of Cancer Biology and Drug Discovery, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan, ROC
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Ion BF, Bushnell EAC, De Luna P, Gauld JW. A Molecular Dynamics (MD) and Quantum Mechanics/Molecular Mechanics (QM/MM) study on Ornithine Cyclodeaminase (OCD): a tale of two iminiums. Int J Mol Sci 2012; 13:12994-3011. [PMID: 23202934 PMCID: PMC3497308 DOI: 10.3390/ijms131012994] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 09/27/2012] [Accepted: 09/27/2012] [Indexed: 11/16/2022] Open
Abstract
Ornithine cyclodeaminase (OCD) is an NAD+-dependent deaminase that is found in bacterial species such as Pseudomonas putida. Importantly, it catalyzes the direct conversion of the amino acid L-ornithine to L-proline. Using molecular dynamics (MD) and a hybrid quantum mechanics/molecular mechanics (QM/MM) method in the ONIOM formalism, the catalytic mechanism of OCD has been examined. The rate limiting step is calculated to be the initial step in the overall mechanism: hydride transfer from the L-ornithine's C(α)-H group to the NAD+ cofactor with concomitant formation of a C(α)=NH(2)+ Schiff base with a barrier of 90.6 kJ mol-1. Importantly, no water is observed within the active site during the MD simulations suitably positioned to hydrolyze the C(α)=NH(2)+ intermediate to form the corresponding carbonyl. Instead, the reaction proceeds via a non-hydrolytic mechanism involving direct nucleophilic attack of the δ-amine at the C(α)-position. This is then followed by cleavage and loss of the α-NH(2) group to give the Δ1-pyrroline-2-carboxylate that is subsequently reduced to L-proline.
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Affiliation(s)
- Bogdan F. Ion
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4, Canada; E-Mails: (B.F.I.); (E.A.C.B.); (P.D.L.)
| | - Eric A. C. Bushnell
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4, Canada; E-Mails: (B.F.I.); (E.A.C.B.); (P.D.L.)
| | - Phil De Luna
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4, Canada; E-Mails: (B.F.I.); (E.A.C.B.); (P.D.L.)
| | - James W. Gauld
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4, Canada; E-Mails: (B.F.I.); (E.A.C.B.); (P.D.L.)
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Meng Z, Lou Z, Liu Z, Li M, Zhao X, Bartlam M, Rao Z. Crystal structure of human pyrroline-5-carboxylate reductase. J Mol Biol 2006; 359:1364-77. [PMID: 16730026 DOI: 10.1016/j.jmb.2006.04.053] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Revised: 04/19/2006] [Accepted: 04/22/2006] [Indexed: 11/17/2022]
Abstract
Pyrroline-5-carboxylate reductase (P5CR) is a universal housekeeping enzyme that catalyzes the reduction of Delta(1)-pyrroline-5-carboxylate (P5C) to proline using NAD(P)H as the cofactor. The enzymatic cycle between P5C and proline is very important for the regulation of amino acid metabolism, intracellular redox potential, and apoptosis. Here, we present the 2.8 Angstroms resolution structure of the P5CR apo enzyme, its 3.1 Angstroms resolution ternary complex with NAD(P)H and substrate-analog. The refined structures demonstrate a decameric architecture with five homodimer subunits and ten catalytic sites arranged around a peripheral circular groove. Mutagenesis and kinetic studies reveal the pivotal roles of the dinucleotide-binding Rossmann motif and residue Glu221 in the human enzyme. Human P5CR is thermostable and the crystals were grown at 37 degrees C. The enzyme is implicated in oxidation of the anti-tumor drug thioproline.
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Affiliation(s)
- Zhaohui Meng
- Tsinghua-IBP Joint Research Group for Structural Biology, Tsinghua University, Beijing, China
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Downs SM, Utecht AM. Metabolism of radiolabeled glucose by mouse oocytes and oocyte-cumulus cell complexes. Biol Reprod 1999; 60:1446-52. [PMID: 10330104 DOI: 10.1095/biolreprod60.6.1446] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
This study was carried out to examine the metabolism of [1-14C]-, [6-14C]-, and [5-3H]glucose by oocyte-cumulus cell complexes (OCC) and denuded oocytes (DO) and to test the hypothesis that metabolism of glucose through the pentose phosphate pathway is associated with meiotic induction. OCC or DO were cultured in hanging drops suspended from the cap of a microfuge tube, with NaOH serving as a trap to collect released 3H2O or 14CO2. Preliminary experiments established that this culture system supports both spontaneous and ligand-induced meiotic maturation. An initial time course experiment (1.5-6 h) showed that hypoxanthine-treated OCC from eCG-primed animals metabolized glucose principally via glycolysis, with an increase to 2.7-fold in response to FSH. Though more [1-14C]glucose was oxidized than [6-14C]glucose, its metabolism was about two orders of magnitude less than that of [5-3H]glucose. Also, FSH significantly increased oxidation of [1-14C]glucose but not [6-14C]glucose, indicating a preferential activation of the pentose phosphate pathway. Pyrroline carboxylate, an activator of the pentose phosphate pathway, increased the activity of this pathway to over 2-fold but failed to affect glucose oxidation through the tricarboxylic acid cycle. Glycolytic metabolism was increased by 25%. The addition of pyruvate to pyruvate-free medium resulted in significant reduction in the metabolism of all three glucose analogues. In OCC retrieved from hCG-injected, primed mice and cultured under hormone-free conditions, metabolic responses were similar to those in FSH-treated complexes cultured in hypoxanthine. DO metabolized glucose, but at a much reduced rate when compared to OCC. Pyruvate reduced the consumption of all three glucose analogues by DO. Pyrroline carboxylate reduced [5-3H]glucose metabolism by DO but had little effect on [1-14C]- and [6-14C]glucose oxidation. These data demonstrate metabolism of glucose by both DO and OCC, but reveal that cumulus cells are more active than the oocyte in this regard. In addition, induction of maturation by FSH, hCG, or pyrroline carboxylate was accompanied by a significant increase in the oxidation of [1-14C]glucose but not [6-14C]glucose by OCC, supporting a proposed role for the pentose phosphate pathway in meiotic induction.
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Affiliation(s)
- S M Downs
- Biology Department, Marquette University, Milwaukee, Wisconsin 53201-1881, USA.
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Mitton KP, Hess JL, Bunce GE. Free amino acids reflect impact of selenite-dependent stress on primary metabolism in rat lens. Curr Eye Res 1997; 16:997-1005. [PMID: 9330851 DOI: 10.1076/ceyr.16.10.997.9016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
PURPOSE A decrease in phase separation temperature, prior to nuclear cataract, has been correlated with elevated free amino acid content. Hence, we determined how selenite-induced stress alters free amino acid pools in the rat lens, following a single subcutaneous dose of sodium selenite (30 nmol g-1 body weight) in 10- to 14-day-old Sprague Dawley rats. RESULT Oxidative stress was evident in lenses 24 h after rats were treated with selenite. Glutathione content was decreased by 60% in the lens cortex and nucleus; the flux of glucose through the pentose phosphate pathway was increased; and glycerol-3-phosphate content was elevated. Amino acid transport, evaluated as 14C-cycloleucine uptake, was not altered, although 14C-glutamine was oxidized at a slower rate. Lenses from treated animals displayed, among the free amino acids, increased glutamine, proline, serine, glycine and the branched chain amino acids, while aspartate, glutamate, and taurine were less. CONCLUSIONS A systemic delivery of sodium selenite caused oxidative stress in the rat lens. Direct effects on primary metabolism altered free amino acid pools that may contribute to transient and permanent changes in lens transparency.
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Affiliation(s)
- K P Mitton
- Laboratory of Mechanisms of Ocular Diseases, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
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