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Rousseau C, Metz R, Kerdraon O, Ouldamer L, Boiffard F, Renaudeau K, Ferrer L, Vercouillie J, Doutriaux-Dumoulin I, Mouton A, Le Thiec M, Morel A, Rusu D, Santiago-Ribeiro MJ, Campion L, Arlicot N, Kraeber-Bodéré F. Pilot Feasibility Study: 18 F-DPA-714 PET/CT Macrophage Imaging in Triple-Negative Breast Cancers (EITHICS). Clin Nucl Med 2024; 49:701-708. [PMID: 38913962 DOI: 10.1097/rlu.0000000000005338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
ABSTRACT Tumor-associated macrophages are targets of interest in triple-negative breast cancer (TNBC). The translocator protein 18 kDa (TSPO) is a sensitive marker for macrophages and holds potential relevance in TNBC stratification. This pilot prospective study (EITHICS, NCT04320030) aimed to assess the potential of TSPO PET/CT imaging using 18 F-DPA-714 in primary TNBC, compared with immunohistochemistry, autoradiography, and TSPO polymorphism. PATIENTS AND METHODS Thirteen TNBC patients were included. They underwent TSPO genotyping (HAB, MAB, LAB), 18 F-FDG PET/CT, and breast MRI. Semiquantitative PET parameters were computed. VOIs were defined on the tumor lesion, healthy breast tissue, and pectoral muscle to obtain SUV, tumor-to-background ratio (TBR), and time-activity curves (TACs). Additionally, immunohistochemistry, 3 H-DPA-714, and 3 H-PK-11195 autoradiography were conducted. RESULTS The majority of TNBC tumors (11/13, 84%) had a preponderance of M2-polarized macrophages with a median proportion of 82% (range, 44%-94%). 18 F-DPA-714 PET/CT clearly identified TNBC tumors with an excellent TBR. Three distinct patterns of 18 F-DPA-714 TACs were identified, categorized as "above muscular," "equal to muscular," and "below muscular" with reference to the muscular background. For the "above muscular" group (2 HAB and 2 MAB), "equal muscular" group (3 HAB, 3 MAB, and 1 LAB), and "below muscular" group (1 LAB and 1 MAB), tumor TACs showed a 18 F-DPA-714 accumulation slope of 1.35, 0.62, and 0.22, respectively, and a median SUV mean of 4.02 (2.09-5.31), 1.66 (0.93-3.07), and 0.61 (0.43-1.02). CONCLUSIONS This study successfully demonstrated TNBC tumor targeting by 18 F-DPA-714 with an excellent TBR, allowing to stratify 3 patterns of uptake potentially influenced by the TSPO polymorphism status. Further studies in larger populations should be performed to evaluate the prognostic value of this new biomarker.
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Affiliation(s)
| | - Raphaël Metz
- From the ICO René Gauducheau, F-44800, Saint-Herblain, France
| | | | | | | | | | | | | | | | - Alexis Mouton
- From the ICO René Gauducheau, F-44800, Saint-Herblain, France
| | - Maelle Le Thiec
- From the ICO René Gauducheau, F-44800, Saint-Herblain, France
| | - Agnès Morel
- From the ICO René Gauducheau, F-44800, Saint-Herblain, France
| | - Daniela Rusu
- From the ICO René Gauducheau, F-44800, Saint-Herblain, France
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2
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Liu H, Marquez RT, Wu X, Li K, Vadlamani S, Li S, Wang Y, Xu L, Wu D. A non-intrusive evaluation method for tumor-targeting characteristics of nanomedicines based on in vivo near-infrared fluorescence imaging. J Mater Chem B 2020; 7:4751-4757. [PMID: 31389969 DOI: 10.1039/c9tb00882a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We developed a novel evaluation method for tumor-targeting characteristics of nanomedicines, average tumor-targeting index (average TTI) and "area under the tumor-targeting index-time curve" (AUTC) were established as the indicators for tumor targeting of nanomedicines based on NIR fluorescence imaging, which helps real-time monitoring of targeting ability and tumor changes in vivo without culling animals.
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Affiliation(s)
- Hao Liu
- Department of Pharmaceutics, School of Pharmacy, Southwest Medical University, Luzhou City, Sichuan Province 646000, P. R. China
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3
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Tang D, Li J, Nickels ML, Huang G, Cohen AS, Manning HC. Preclinical Evaluation of a Novel TSPO PET Ligand 2-(7-Butyl-2-(4-(2-[ 18F]Fluoroethoxy)phenyl)-5-Methylpyrazolo[1,5-a]Pyrimidin-3-yl)-N,N-Diethylacetamide ( 18F-VUIIS1018A) to Image Glioma. Mol Imaging Biol 2019; 21:113-121. [PMID: 29869061 DOI: 10.1007/s11307-018-1198-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
PURPOSE There is an urgent need for the development of novel positron emission tomography (PET) tracers for glioma imaging. In this study, we developed a novel PET probe ([18F]VUIIS1018A) by targeting translocator protein (TSPO), an imaging biomarker for glioma. The purpose of this preclinical study was to evaluate this novel TSPO probe for glioma imaging. PROCEDURES In this study, we synthesized [19F]VUIIS1018A and the precursor for radiosynthesis of [18F]VUIIS1018A. TSPO binding affinity was confirmed using a radioligand competitive binding assay in C6 glioma cell lysate. Further, dynamic imaging studies were performed in rats using a microPET system. These studies include displacement and blocking studies for ligand reversibility and specificity evaluation, and compartment modeling of PET data for pharmacokinetic parameter measurement using metabolite-corrected arterial input functions and PMOD. RESULTS Compared to previously reported TSPO tracers including [18F]VUIIS1008 and [18F]DPA-714, the novel tracer [18F]VUIIS1018A demonstrated higher binding affinity and BPND. Pretreatment with the cold analog [19F]VUIIS1018A could partially block tumor accumulation of this novel tracer. Further, compartment modeling of this novel tracer also exhibited a greater tumor-to-background ratio, a higher tumor binding potential and a lower brain binding potential when compared with other TSPO probes, such as [18F]DPA-714 and [18F]VUIIS1008. CONCLUSIONS These studies illustrate that [18F]VUIIS1018A can serve as a promising TSPO PET tracer for glioma imaging and potentially imaging of other solid tumors.
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Affiliation(s)
- Dewei Tang
- Center for Molecular Imaging, Shanghai University of Medicine & Health Sciences, Shanghai, China.,Department of Nuclear Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 160 Pujian Road, Pudong New District, Shanghai, 200127, China
| | - Jun Li
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.,Vanderbilt Center for Molecular Probes (CMP), Vanderbilt University Medical School, 1161 21st Ave. S., AA 1105 MCN, Nashville, TN, 37232-2310, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Michael L Nickels
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.,Vanderbilt Center for Molecular Probes (CMP), Vanderbilt University Medical School, 1161 21st Ave. S., AA 1105 MCN, Nashville, TN, 37232-2310, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Gang Huang
- Center for Molecular Imaging, Shanghai University of Medicine & Health Sciences, Shanghai, China.,Department of Nuclear Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 160 Pujian Road, Pudong New District, Shanghai, 200127, China
| | - Allison S Cohen
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.,Vanderbilt Center for Molecular Probes (CMP), Vanderbilt University Medical School, 1161 21st Ave. S., AA 1105 MCN, Nashville, TN, 37232-2310, USA
| | - H Charles Manning
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA. .,Vanderbilt Center for Molecular Probes (CMP), Vanderbilt University Medical School, 1161 21st Ave. S., AA 1105 MCN, Nashville, TN, 37232-2310, USA. .,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA. .,Program in Chemical and Physical Biology, Vanderbilt University Medical Center, Nashville, TN, USA. .,Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN, USA. .,Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA. .,Department of Neurosurgery, Vanderbilt University Medical Center, Nashville, TN, USA.
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4
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Xia Y, Ledwitch K, Kuenze G, Duran A, Li J, Sanders CR, Manning C, Meiler J. A unified structural model of the mammalian translocator protein (TSPO). JOURNAL OF BIOMOLECULAR NMR 2019; 73:347-364. [PMID: 31243635 PMCID: PMC8006375 DOI: 10.1007/s10858-019-00257-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Accepted: 06/10/2019] [Indexed: 05/10/2023]
Abstract
The translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor (PBR), is a membrane protein located on the outer mitochondrial membrane. Experimentally-derived structures of mouse TSPO (mTSPO) and its homologs from bacterial species have been determined by NMR spectroscopy and X-ray crystallography, respectively. These structures and ligand interactions within the TSPO binding pocket display distinct differences. Here, we leverage experimental and computational studies to derive a unified structural model of mTSPO in the presence and absence of the TSPO ligand, PK11195, and study the effects of DPC detergent micelles on the TSPO structure and ligand binding. From this work, we conclude that that the lipid-mimetic system used to solubilize mTSPO for NMR studies thermodynamically destabilizes the protein, introduces structural perturbations, and alters the characteristics of ligand binding. Furthermore, we used Rosetta to construct a unified mTSPO model that reconciles deviating features of the mammalian and bacterial TSPO. These deviating features are likely a consequence of the detergent system used for structure determination of mTSPO by NMR. The unified mTSPO model agrees with available experimental NMR data, appears to be physically realistic (i.e. thermodynamically not frustrated as judged by the Rosetta energy function), and simultaneously shares the structural features observed in sequence-conserved regions of the bacterial proteins. Finally, we identified the binding site for an imaging ligand VUIIS8310 that is currently positioned for clinical translation using NMR spectroscopy and propose a computational model of the VUIIS8310-mTSPO complex.
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Affiliation(s)
- Yan Xia
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Kaitlyn Ledwitch
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Amanda Duran
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Jun Li
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Charles R Sanders
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37240, USA
| | - Charles Manning
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA.
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA.
- Department of Chemistry, Center for Structural Biology, Vanderbilt University, MRBIII 5144B, Nashville, TN, 37232, USA.
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Li J, Smith JA, Dawson ES, Fu A, Nickels ML, Schulte ML, Manning HC. Optimized Translocator Protein Ligand for Optical Molecular Imaging and Screening. Bioconjug Chem 2017; 28:1016-1023. [PMID: 28156095 DOI: 10.1021/acs.bioconjchem.6b00711] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Translocator protein (TSPO) is a validated target for molecular imaging of a variety of human diseases and disorders. Given its involvement in cholesterol metabolism, TSPO expression is commonly elevated in solid tumors, including glioma, colorectal cancer, and breast cancer. TSPO ligands capable of detection by optical imaging are useful molecular tracers for a variety of purposes that range from quantitative biology to drug discovery. Leveraging our prior optimization of the pyrazolopyrimidine TSPO ligand scaffold for cancer imaging, we report herein a new generation of TSPO tracers with superior binding affinity and suitability for optical imaging and screening. In total, seven candidate TSPO tracers were synthesized and vetted in this study; the most promising tracer identified (29, Kd = 0.19 nM) was the result of conjugating a high-affinity TSPO ligand to a fluorophore used routinely in biological sciences (FITC) via a functional carbon linker of optimal length. Computational modeling suggested that an n-alkyl linker of eight carbons in length allows for positioning of the bulky fluorophore distal to the ligand binding domain and toward the solvent interface, minimizing potential ligand-protein interference. Probe 29 was found to be highly suitable for in vitro imaging of live TSPO-expressing cells and could be deployed as a ligand screening and discovery tool. Competitive inhibition of probe 29 quantified by fluorescence and 3H-PK11195 quantified by traditional radiometric detection resulted in equivalent affinity data for two previously reported TSPO ligands. This study introduces the utility of TSPO ligand 29 for in vitro imaging and screening and provides a structural basis for the development of future TSPO imaging ligands bearing bulky signaling moieties.
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Affiliation(s)
- Jun Li
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
| | - Jarrod A Smith
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
| | - Eric S Dawson
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
| | - Allie Fu
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
| | - Michael L Nickels
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
| | - Michael L Schulte
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
| | - H Charles Manning
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
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6
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TSPO: kaleidoscopic 18-kDa amid biochemical pharmacology, control and targeting of mitochondria. Biochem J 2016; 473:107-21. [PMID: 26733718 DOI: 10.1042/bj20150899] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The 18-kDa translocator protein (TSPO) localizes in the outer mitochondrial membrane (OMM) of cells and is readily up-regulated under various pathological conditions such as cancer, inflammation, mechanical lesions and neurological diseases. Able to bind with high affinity synthetic and endogenous ligands, its core biochemical function resides in the translocation of cholesterol into the mitochondria influencing the subsequent steps of (neuro-)steroid synthesis and systemic endocrine regulation. Over the years, however, TSPO has also been linked to core cellular processes such as apoptosis and autophagy. It interacts and forms complexes with other mitochondrial proteins such as the voltage-dependent anion channel (VDAC) via which signalling and regulatory transduction of these core cellular events may be influenced. Despite nearly 40 years of study, the precise functional role of TSPO beyond cholesterol trafficking remains elusive even though the recent breakthroughs on its high-resolution crystal structure and contribution to quality-control signalling of mitochondria. All this along with a captivating pharmacological profile provides novel opportunities to investigate and understand the significance of this highly conserved protein as well as contribute the development of specific therapeutics as presented and discussed in the present review.
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7
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DE Rosa A, Zappavigna S, Villa MR, Improta S, Cesario E, Mastrullo L, Caraglia M, Stiuso P. Prognostic role of translocator protein and oxidative stress markers in chronic lymphocytic leukemia patients treated with bendamustine plus rituximab. Oncol Lett 2014; 9:1327-1332. [PMID: 25663907 PMCID: PMC4315100 DOI: 10.3892/ol.2014.2817] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 11/26/2014] [Indexed: 01/21/2023] Open
Abstract
Principally located in the outer mitochondrial membrane, the translocator protein (TSPO) is an 18-kDa transmembrane protein that is a key component of the mitochondrial permeability transition pore. TSPO is associated with a number of biological processes, including apoptosis, the regulation of cellular proliferation, porphyrin transport and heme biosynthesis, immunomodulation, anion transport and the regulation of steroidogenesis. Thus, numerous studies have proposed TSPO as a promising target for novel therapeutic agents, particularly for the treatment of cancer. In the present study, the response of 30 consecutive chronic lymphocytic leukemia (CLL) patients to bendamustine and rituximab treatment was evaluated according to TSPO expression levels. Furthermore, thiobarbituric acid reactive substances (TBARS) and nitric oxide (NO) levels, as well as caspase-3 activity were determined. Compared with the lymphocytes of healthy donors, the 30 consecutive CLL patients exhibited increased TSPO expression levels, decreased TBARS and NO levels and reduced caspase-3 activity. Six months after the treatment commenced, the TSPO/mitochondria ratio resembled that of the healthy controls in 24/30 CLL patients. In addition, an increase in TBARS and NO levels, two markers of oxidative stress, and a potentiation of caspase-3 activity in all responder patients was observed. Notably, the six patients who appeared to be resistant to treatment also displayed higher TSPO levels, and lower caspase-3 activity and TBARS levels. These data indicate that TSPO expression may be a molecular prognostic factor in CLL patients.
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Affiliation(s)
- Aniello DE Rosa
- Local Sanitary Agency, Naples 3 Southern, Torre del Grecco, Naples I-80059, Italy
| | - Silvia Zappavigna
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Naples I-80138, Italy
| | | | | | - Elena Cesario
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Naples I-80138, Italy
| | - Lucia Mastrullo
- Hematology Unit, San Gennaro Hospital, Naples I-80131, Italy
| | - Michele Caraglia
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Naples I-80138, Italy
| | - Paola Stiuso
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Naples I-80138, Italy
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8
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Tang D, Nickels ML, Tantawy MN, Buck JR, Manning HC. Preclinical imaging evaluation of novel TSPO-PET ligand 2-(5,7-Diethyl-2-(4-(2-[(18)F]fluoroethoxy)phenyl)pyrazolo[1,5-a]pyrimidin-3-yl)-N,N-diethylacetamide ([ (18)F]VUIIS1008) in glioma. Mol Imaging Biol 2014; 16:813-20. [PMID: 24845529 PMCID: PMC4372299 DOI: 10.1007/s11307-014-0743-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE Translocator protein (TSPO) concentrations are elevated in glioma, suggesting a role for TSPO positron emission tomography (PET) imaging in this setting. In preclinical PET studies, we evaluated a novel, high-affinity TSPO PET ligand, [(18)F]VUIIS1008, in healthy mice and glioma-bearing rats. PROCEDURES Dynamic PET data were acquired simultaneously with [(18)F]VUIIS1008 injection, with binding reversibility and specificity evaluated in vivo by non-radioactive ligand displacement or blocking. Compartmental analysis of PET data was performed using metabolite-corrected arterial input functions. Imaging was validated with histology and immunohistochemistry. RESULTS [(18)F]VUIIS1008 exhibited rapid uptake in TSPO-rich organs. PET ligand uptake was displaceable with non-radioactive VUIIS1008 or PBR06 in mice. Tumor accumulation of [(18)F]VUIIS1008 was blocked by pretreatment with VUIIS1008 in rats. [(18)F]VUIIS1008 exhibited improved tumor-to-background ratio and higher binding potential in tumors compared to a structurally similar pyrazolopyrimidine TSPO ligand, [(18)F]DPA-714. CONCLUSIONS The PET ligand [(18)F]VUIIS1008 exhibits promising characteristics as a tracer for imaging glioma. Further translational studies appear warranted.
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Affiliation(s)
- Dewei Tang
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee 37232
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232
| | - Michael L. Nickels
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee 37232
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232
| | - M. Noor Tantawy
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee 37232
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232
| | - Jason R. Buck
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee 37232
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232
| | - H. Charles Manning
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee 37232
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232
- Program in Chemical and Physical Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37232
- Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee 37232
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37232
- Department of Neurosurgery, Vanderbilt University Medical Center, Nashville, Tennessee 37232
- Vanderbilt Institute of Chemical Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37232
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9
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Vasdev N, Green DE, Vines DC, McLarty K, McCormick PN, Moran MD, Houle S, Wilson AA, Reilly RM. Positron-Emission Tomography Imaging of the TSPO with [18F]FEPPA in a Preclinical Breast Cancer Model. Cancer Biother Radiopharm 2013; 28:254-9. [DOI: 10.1089/cbr.2012.1196] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Neil Vasdev
- PET Centre, Centre for Addiction and Mental Health, Toronto, Ontario
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - David E. Green
- STTARR Innovation Centre, Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - Douglass C. Vines
- STTARR Innovation Centre, Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada
- Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
| | - Kristin McLarty
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Patrick N. McCormick
- PET Centre, Centre for Addiction and Mental Health, Toronto, Ontario
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Matthew D. Moran
- PET Centre, Centre for Addiction and Mental Health, Toronto, Ontario
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Sylvain Houle
- PET Centre, Centre for Addiction and Mental Health, Toronto, Ontario
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Alan A. Wilson
- PET Centre, Centre for Addiction and Mental Health, Toronto, Ontario
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Raymond M. Reilly
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
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10
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Tang D, Hight MR, McKinley ET, Fu A, Buck JR, Smith RA, Tantawy MN, Peterson TE, Colvin DC, Ansari MS, Nickels M, Manning HC. Quantitative preclinical imaging of TSPO expression in glioma using N,N-diethyl-2-(2-(4-(2-18F-fluoroethoxy)phenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)acetamide. J Nucl Med 2012; 53:287-94. [PMID: 22251555 DOI: 10.2967/jnumed.111.095653] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
UNLABELLED There is a critical need to develop and rigorously validate molecular imaging biomarkers to aid diagnosis and characterization of primary brain tumors. Elevated expression of translocator protein (TSPO) has been shown to predict disease progression and aggressive, invasive behavior in a variety of solid tumors. Thus, noninvasive molecular imaging of TSPO expression could form the basis of a novel, predictive cancer imaging biomarker. In quantitative preclinical PET studies, we evaluated a high-affinity pyrazolopyrimidinyl-based TSPO imaging ligand, N,N-diethyl-2-(2-(4-(2-(18)F-fluoroethoxy)phenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)acetamide ((18)F-DPA-714), as a translational probe for quantification of TSPO levels in glioma. METHODS Glioma-bearing rats were imaged with (18)F-DPA-714 in a small-animal PET system. Dynamic images were acquired simultaneously on injection of (18)F-DPA-714 (130-200 MBq/0.2 mL). Blood was collected to derive the arterial input function (AIF), with high-performance liquid chromatography radiometabolite analysis performed on selected samples for AIF correction. Compartmental modeling was performed using the corrected AIF. Specific tumor cell binding of DPA-714 was evaluated by radioligand displacement of (3)H-PK 11195 with DPA-714 in vitro and displacement of (18)F-DPA-714 with an excess of DPA-714 in vivo. Immediately after imaging, tumor and healthy brain tissues were harvested for validation by Western blotting and immunohistochemistry. RESULTS (18)F-DPA-714 was found to preferentially accumulate in tumors, with modest uptake in the contralateral brain. Infusion with DPA-714 (10 mg/kg) displaced (18)F-DPA-714 binding by greater than 60% on average. Tumor uptake of (18)F-DPA-714 was similar to another high-affinity TSPO imaging ligand, (18)F-N-fluoroacetyl-N-(2,5-dimethoxybenzyl)-2-phenoxyaniline, and agreed with ex vivo assay of TSPO levels in tumor and healthy brain. CONCLUSION These studies illustrate the feasibility of using (18)F-DPA-714 for visualization of TSPO-expressing brain tumors. Importantly, (18)F-DPA-714 appears suitable for quantitative assay of tumor TSPO levels in vivo. Given the relationship between elevated TSPO levels and poor outcome in oncology, these studies suggest the potential of (18)F-DPA-714 PET to serve as a novel predictive cancer imaging modality.
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Affiliation(s)
- Dewei Tang
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
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11
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Zheng J, Boisgard R, Siquier-Pernet K, Decaudin D, Dollé F, Tavitian B. Differential Expression of the 18 kDa Translocator Protein (TSPO) by Neoplastic and Inflammatory Cells in Mouse Tumors of Breast Cancer. Mol Pharm 2011; 8:823-32. [DOI: 10.1021/mp100433c] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Jinzi Zheng
- Laboratoire d'Imagerie Moléculaire Expérimentale, Université Paris Sud, INSERM Unit 1023, 4 Place du Général Leclerc, F-91400 Orsay, France
| | - Raphaël Boisgard
- Laboratoire d'Imagerie Moléculaire Expérimentale, Université Paris Sud, INSERM Unit 1023, 4 Place du Général Leclerc, F-91400 Orsay, France
| | - Karine Siquier-Pernet
- Laboratoire d'Imagerie Moléculaire Expérimentale, Université Paris Sud, INSERM Unit 1023, 4 Place du Général Leclerc, F-91400 Orsay, France
| | - Didier Decaudin
- Laboratory of Preclinical Investigation, Institut Curie, 26 rue d'Ulm, F-75248 Paris, France
| | - Frédéric Dollé
- Institut d'Imagerie BioMédicale, Service Hospitalier Frédéric Joliot, Commissariat a l'Énergie Atomique, 4 Place du Général Leclerc, F-91400, France
| | - Bertrand Tavitian
- Laboratoire d'Imagerie Moléculaire Expérimentale, Université Paris Sud, INSERM Unit 1023, 4 Place du Général Leclerc, F-91400 Orsay, France
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12
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Batarseh A, Papadopoulos V. Regulation of translocator protein 18 kDa (TSPO) expression in health and disease states. Mol Cell Endocrinol 2010; 327:1-12. [PMID: 20600583 PMCID: PMC2922062 DOI: 10.1016/j.mce.2010.06.013] [Citation(s) in RCA: 217] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Accepted: 06/17/2010] [Indexed: 01/12/2023]
Abstract
Translocator protein (TSPO) is an 18 kDa high affinity cholesterol- and drug-binding protein found primarily in the outer mitochondrial membrane. Although TSPO is found in many tissue types, it is expressed at the highest levels under normal conditions in tissues that synthesize steroids. TSPO has been associated with cholesterol import into mitochondria, a key function in steroidogenesis, and directly or indirectly with multiple other cellular functions including apoptosis, cell proliferation, differentiation, anion transport, porphyrin transport, heme synthesis, and regulation of mitochondrial function. Aberrant expression of TSPO has been linked to multiple diseases, including cancer, brain injury, neurodegeneration, and ischemia-reperfusion injury. There has been an effort during the last decade to understand the mechanisms regulating tissue- and disease-specific TSPO expression and to identify pharmacological means to control its expression. This review focuses on the current knowledge regarding the chemicals, hormones, and molecular mechanisms regulating Tspo gene expression under physiological conditions in a tissue- and disease-specific manner. The results described here provide evidence that the PKCepsilon-ERK1/2-AP-1/STAT3 signal transduction pathway is the primary regulator of Tspo gene expression in normal and pathological tissues expressing high levels of TSPO.
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Affiliation(s)
- Amani Batarseh
- Department of Biochemistry and Molecular and Cell Biology, Georgetown University Medical Center, Washington, D.C. 20057, USA
- The Research Institute of the McGill University Health Centre and the Department of Medicine, Biochemistry, McGill University, 1650 Cedar Avenue, Montreal, Quebec H3G 1A4, Canada
| | - Vassilios Papadopoulos
- Department of Biochemistry and Molecular and Cell Biology, Georgetown University Medical Center, Washington, D.C. 20057, USA
- The Research Institute of the McGill University Health Centre and the Department of Medicine, Biochemistry, McGill University, 1650 Cedar Avenue, Montreal, Quebec H3G 1A4, Canada
- Department of Pharmacology and Therapeutics, McGill University, 1650 Cedar Avenue, Montreal, Quebec H3G 1A4, Canada
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13
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Molecular imaging of the translocator protein (TSPO) in a pre-clinical model of breast cancer. Mol Imaging Biol 2009; 12:349-58. [PMID: 19949989 DOI: 10.1007/s11307-009-0270-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Revised: 05/20/2009] [Accepted: 05/29/2009] [Indexed: 10/20/2022]
Abstract
PURPOSE To quantitatively evaluate the utility of a translocator protein (TSPO)-targeted near-infrared (NIR) probe (NIR-conPK11195) for in vivo molecular imaging of TSPO in breast cancer. PROCEDURES NIR-conPK11195 uptake and TSPO-specificity were validated in TSPO-expressing human breast adenocarcinoma cells (MDA-MB-231). In vivo NIR-conPK11195 biodistribution and accumulation were quantitatively evaluated in athymic nude mice bearing MDA-MB-231 xenografts. RESULTS Fluorescence micrographs illustrated intracellular labeling of MDA-MB-231 cells by NIR-conPK11195. Quantitative uptake and competition assays demonstrated dose-dependent (p < 0.001) and TSPO-specific (p < 0.001) NIR-conPK11195 uptake. In vivo, NIR-conPK11195 preferentially labeled MDA-MB-231 tumors with an 11-fold (p < 0.001) and 7-fold (p < 0.001) contrast enhancement over normal tissue and unconjugated NIR dye, respectively. CONCLUSIONS NIR-conPK11195 appears to be a promising TSPO-targeted molecular imaging agent for visualization and quantification of breast cancer cells in vivo. This research represents the first study to demonstrate the feasibility of TSPO imaging as an alternative breast cancer imaging approach.
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14
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The 18-kDa translocator protein, formerly known as the peripheral-type benzodiazepine receptor, confers proapoptotic and antineoplastic effects in a human colorectal cancer cell line. Pharmacogenet Genomics 2008; 18:977-88. [DOI: 10.1097/fpc.0b013e3283117d52] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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15
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Li W, Hardwick MJ, Rosenthal D, Culty M, Papadopoulos V. Peripheral-type benzodiazepine receptor overexpression and knockdown in human breast cancer cells indicate its prominent role in tumor cell proliferation. Biochem Pharmacol 2006; 73:491-503. [PMID: 17126818 DOI: 10.1016/j.bcp.2006.10.025] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Revised: 10/20/2006] [Accepted: 10/24/2006] [Indexed: 10/23/2022]
Abstract
The peripheral-type benzodiazepine receptor (PBR), an 18-kDa high affinity drug and cholesterol binding protein, is expressed at high levels in various cancers. Its expression is positively correlated with aggressive metastatic behavior in human breast cancer cells. To determine the role of PBR in tumor progression, two human mammary carcinoma cell lines were utilized: the non-aggressive MCF-7 cell line, which expresses extremely low PBR levels, and the highly aggressive MDA-MB-231 cell line, which has much higher PBR levels. We have generated stably transfected lines of the tetracycline-repressible MCF-7 cell line (MCF-7 Tet-Off) with inducible human PBR cDNA. Induction of PBR expression in MCF-7 Tet-Off cells increased PBR ligand binding and cell proliferation. Transfection of MDA-MB-231 cells with multiple siRNAs complementary to PBR (PBR-siRNAs) led to different levels of PBR mRNA knockdown. Lentiviral-mediated PBR RNA interference in MDA-MB-231 cells decreased PBR levels by 50%. Decreased PBR expression was associated with cell cycle arrest at G2 phase, decreased cell proliferation, and significant increases in the protein levels of the cyclin-dependent kinase inhibitor p21(WAF/CIP1). These changes were accompanied by p53 activation seen as increased p53 phosphorylation (Ser15). In parallel, increased proteolytic activation of caspase-3 was also observed. Taken together these results suggest that PBR protein expression is directly involved in regulating cell survival and proliferation in human breast cancer cells by influencing signaling mechanisms involved in cell cycle control and apoptosis.
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MESH Headings
- Apoptosis/drug effects
- Apoptosis/physiology
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Caspase 3/metabolism
- Cell Line
- Cell Line, Tumor
- Cell Proliferation
- Cell Survival/drug effects
- Cell Survival/physiology
- Cyclin A/metabolism
- Cyclin-Dependent Kinase Inhibitor p21/metabolism
- Dose-Response Relationship, Drug
- Doxycycline/pharmacology
- G1 Phase/drug effects
- Humans
- Immunohistochemistry
- Models, Biological
- Proliferating Cell Nuclear Antigen/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Radioligand Assay
- Receptors, GABA-A/genetics
- Receptors, GABA-A/metabolism
- Receptors, GABA-A/physiology
- Retinoblastoma Protein/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Time Factors
- Transfection
- Vimentin/biosynthesis
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Affiliation(s)
- Wenping Li
- Department of Biochemistry & Molecular and Cellular Biology, Georgetown University Medical Center, Washington, DC 20057, USA
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16
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Cellai C, Laurenzana A, Vannucchi AM, Caporale R, Paglierani M, Di Lollo S, Pancrazzi A, Paoletti F. Growth inhibition and differentiation of human breast cancer cells by the PAFR antagonist WEB-2086. Br J Cancer 2006; 94:1637-42. [PMID: 16721373 PMCID: PMC2361325 DOI: 10.1038/sj.bjc.6603156] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
WEB-2086 – an antagonist of platelet-activating factor receptor (PAFR) with known anti-inflammatory, antiangiogenic and antileukaemic properties – also proved to inhibit the proliferation in human solid tumour cell lines of different histology, and with much higher efficacy than in normal fibroblasts. A detailed analysis of WEB-2086 anticancer activity was then performed focusing on breast adenocarcinoma MCF-7 and MDA-MB-231 cells. WEB-2086-treated cells, either expressing (MCF-7) or unexpressing (MDA-MB-231) the oestrogen receptor (ER)α, underwent a dose-dependent growth arrest (IC50=0.65±0.09 and 0.41±0.07 mM, respectively) and accumulation in G0–G1 phase. WEB-2086 also induced morphological and functional changes typical of mature mammary phenotype including (i) cell enlargement and massive neutral lipid deposition (best accomplished in MCF-7 cells); (ii) decrease in motility and active cathepsin D levels (mainly observed in highly invasive MDA-MB-231 cells). The expression of ERα was neither increased nor reactivated in treated MCF-7 or MDA-MB-231 cells, respectively. WEB-2086-induced differentiation in breast cancer cells involved the upregulation of PTEN, a key tumour suppressor protein opposing tumorigenesis, and was apparently independent of p53, PAFR, peripheral benzodiazepine receptor and ERα status. Overall, WEB-2086 can be proposed as an effective antiproliferative and differentiative agent with interesting translational opportunities to treat breast cancers in support to conventional chemotherapy.
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Affiliation(s)
- C Cellai
- Department of Experimental Pathology and Oncology, School of Medicine, University of Florence, Viale G. B. Morgagni 50, 50134 Florence, Italy
| | - A Laurenzana
- Department of Experimental Pathology and Oncology, School of Medicine, University of Florence, Viale G. B. Morgagni 50, 50134 Florence, Italy
| | - A M Vannucchi
- Department of Haematology, University of Florence, Viale Pieraccini 17, 50139 Florence, Italy
| | - R Caporale
- Department of Haematology, University of Florence, Viale Pieraccini 17, 50139 Florence, Italy
| | - M Paglierani
- Department of Human Pathology and Oncology, School of Medicine, University of Florence, Viale Pieraccini 17, 50139 Florence, Italy
| | - S Di Lollo
- Department of Human Pathology and Oncology, School of Medicine, University of Florence, Viale Pieraccini 17, 50139 Florence, Italy
| | - A Pancrazzi
- Department of Haematology, University of Florence, Viale Pieraccini 17, 50139 Florence, Italy
| | - F Paoletti
- Department of Experimental Pathology and Oncology, School of Medicine, University of Florence, Viale G. B. Morgagni 50, 50134 Florence, Italy
- E-mail:
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Manning HC, Smith SM, Sexton M, Haviland S, Bai M, Cederquist K, Stella N, Bornhop DJ. A peripheral benzodiazepine receptor targeted agent for in vitro imaging and screening. Bioconjug Chem 2006; 17:735-40. [PMID: 16704212 DOI: 10.1021/bc060020b] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We developed a molecular imaging agent (MIA), a conjugable form of PK11195 (conPK11195) coupled to a lissamine dye (Liss-ConPK11195), which targets the peripheral benzodiazepine receptor (PBR). To determine that our compound specifically binds to this 18 kDa protein, primarily expressed on the mitochondria, we performed classic binding studies on live MDA-MB-231 breast cancer cells and measured fluorescence in cell fractions of C6 glioma cells. We found that conPK11195 conjugated to the fluorophore retained significant binding to its target. Here we demonstrate the utility of the agent for in vitro imaging of live cells by specific binding to the protein of interest.
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Affiliation(s)
- H Charles Manning
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA
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18
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Costa B, Salvetti A, Rossi L, Spinetti F, Lena A, Chelli B, Rechichi M, Da Pozzo E, Gremigni V, Martini C. Peripheral benzodiazepine receptor: characterization in human T-lymphoma Jurkat cells. Mol Pharmacol 2005; 69:37-44. [PMID: 16189298 DOI: 10.1124/mol.105.015289] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Peripheral benzodiazepine receptor (PBR) has been considered a promising drug target for cancer therapy, and several ligands have been developed for this purpose. Human T-lymphoma Jurkat cells have been considered as lacking PBR and are often used as negative control to prove the specificity of PBR ligands effects. It is surprising that we evidenced PBR protein expression in this cell line by means of Western blotting and immunocytochemistry assays using specific anti-PBR antibodies. PBR intracellular localization was evidenced in mitochondria and nuclei, as demonstrated by confocal and electron microscopy. The binding of the [(3)H]4'-chloro derivative of diazepam [(3)H]7-chloro-5-(4-chlorophenyl)-1,3-dihydro-1-methyl-2H-1,4-benzodiazepin-2-one (Ro5-4864) and the isoquinoline carboxamide derivative [(3)H]1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3 isoquinolinecarboxamide (PK11195) evidenced a single class of binding sites with an unusual affinity constant (K(d)) of 1.77 +/- 0.30 and 2.20 +/- 0.20 microM, respectively. The pharmacological profile of the classic ligands showed that PK11195 was the most potent inhibitor in the radioligand binding assays followed by Ro5-4864 and diazepam, whereas clonazepam, a specific ligand for the central-type receptor, showed a K(i) >1.0 x 10(-4) M. By a combined strategy of reverse transcriptase-polymerase chain reaction and Southern blot experiments, we succeeded in isolating and cloning the full-length Jurkat PBR cDNA, called JuPBR. The JuPBR gene showed two single-nucleotide polymorphisms resulting in the two substitutions, Ala147 --> threonine and His162 --> arginine, of PBR amino acidic sequence. In conclusion, for the first time, we demonstrated PBR expression in Jurkat cells: the protein bound classic PBR ligands with micromolar affinity constants and presented a modified amino acidic sequence consequent to the detection of two gene polymorphisms.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Benzodiazepinones/pharmacology
- Blotting, Western
- Cloning, Molecular
- DNA Primers
- DNA, Complementary
- Humans
- Immunohistochemistry
- Isoquinolines/pharmacology
- Jurkat Cells
- Lymphoma, T-Cell/metabolism
- Lymphoma, T-Cell/pathology
- Microscopy, Electron
- Point Mutation
- Radioligand Assay
- Rats
- Receptors, GABA-A/chemistry
- Receptors, GABA-A/genetics
- Receptors, GABA-A/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Homology, Amino Acid
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Affiliation(s)
- Barbara Costa
- Department of Psychiatry, Neurobiology, Pharmacology and Biotechnology, University of Pisa, via Bonanno, 6-56126 Pisa, Italy
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19
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Maaser K, Sutter AP, Scherübl H. Mechanisms of mitochondrial apoptosis induced by peripheral benzodiazepine receptor ligands in human colorectal cancer cells. Biochem Biophys Res Commun 2005; 332:646-52. [PMID: 15907803 DOI: 10.1016/j.bbrc.2005.05.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2005] [Accepted: 05/03/2005] [Indexed: 10/25/2022]
Abstract
Specific ligands of the peripheral benzodiazepine receptor (PBR) have been shown to induce apoptosis in gastrointestinal cancers. The aim of this study was to characterize the signaling pathways of PBR ligand-induced apoptosis. FGIN-1-27 but not PK 11195-induced apoptosis was associated with a decrease of mitochondrial membrane potential and an increase of mitochondrial volume in HT29 colorectal cancer cells. However, PK 11195-elicited apoptosis was associated with a downregulation of Bcl-2, translocation of Bax to the mitochondria including subsequent oligomerization, and activation of caspase-9, indicating the involvement of mitochondria in PK 11195-induced apoptosis. Moreover, PK 11195-induced apoptosis was associated with the generation of reactive oxygen species. This study demonstrates a novel mechanism of PK 11195-induced mitochondrial apoptosis without alteration of the mitochondrial membrane potential. The characterization of signaling pathways associated with PBR ligand-induced apoptosis will build the base for a future use of these ligands in anti-neoplastic therapeutic approaches.
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Affiliation(s)
- Kerstin Maaser
- Medical Clinic I, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, 12200 Berlin, Germany
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20
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Manning HC, Goebel T, Thompson RC, Price RR, Lee H, Bornhop DJ. Targeted molecular imaging agents for cellular-scale bimodal imaging. Bioconjug Chem 2005; 15:1488-95. [PMID: 15546219 DOI: 10.1021/bc049904q] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular imaging is a powerful tool that has the ability to elucidate biochemical mechanisms and signal the early onset of disease. Overexpression of the peripheral benzodiazepine receptor (PBR) has been observed in a variety disease states, including glioblastoma, breast cancer, and Alzheimer's disease. Thus, the PBR could be an attractive target for molecular imaging. In this paper, the authors report cellular uptake and multimodal (MRI and fluorescence) imaging of PBR-overexpressing C6 glioblastoma (brain cancer) cells using a cocktail administration approach and a new PBR targeted lanthanide chelate molecular imaging agent.
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Affiliation(s)
- H Charles Manning
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, USA.
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21
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Maaser K, Grabowski P, Oezdem Y, Krahn A, Heine B, Stein H, Buhr H, Zeitz M, Scherübl H. Up-Regulation of the Peripheral Benzodiazepine Receptor during Human Colorectal Carcinogenesis and Tumor Spread. Clin Cancer Res 2005; 11:1751-6. [PMID: 15755996 DOI: 10.1158/1078-0432.ccr-04-1955] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The peripheral benzodiazepine receptor (PBR) is overexpressed in a variety of cancers. In Unio Internationale Contra Cancrum (UICC) III colorectal cancers, a high level of PBR overexpression correlates with poor prognosis. However, little is known about the role of PBR in the development and progression of colorectal cancer. This study addresses the up-regulation of PBR during colorectal carcinogenesis and tumor spread. One hundred sixteen consecutive patients undergoing surgery for colorectal cancer with either regional (59 patients) or distant metastases (57 patients) were followed-up for 5 years or until death. Twenty-four of the 59 patients with initial UICC stage III cancers later developed distant metastases. PBR overexpression in tumor specimens was determined by immunohistochemistry. UICC stage III patients with colorectal primaries highly overexpressing PBR developed metastases significantly more often than patients with low PBR overexpression in their primary carcinoma. In 54 of the 116 patients adenomas and/or metastases and/or recurrences were available to be studied for PBR up-regulation during colorectal carcinogenesis and tumor spread. PBR was found to be overexpressed in 86% of early and late adenomas. Furthermore, 85% of primaries and of 86% of metastases displayed PBR overexpression. PBR overexpression was also detected at the mRNA level as revealed by real-time PCR. The extent of PBR protein overexpression was equivalent in colorectal adenomas and carcinomas but slightly increased in metastases. These data suggest a functional role of PBR during colorectal carcinogenesis and tumor spread. Thus, PBR qualifies as a target for innovative diagnostic and therapeutic approaches.
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Affiliation(s)
- Kerstin Maaser
- Medical Clinic I, Institute of Pathology, and Department of Surgery, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin, Germany
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22
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Hans G, Wislet-Gendebien S, Lallemend F, Robe P, Rogister B, Belachew S, Nguyen L, Malgrange B, Moonen G, Rigo JM. Peripheral benzodiazepine receptor (PBR) ligand cytotoxicity unrelated to PBR expression. Biochem Pharmacol 2005; 69:819-30. [PMID: 15710359 DOI: 10.1016/j.bcp.2004.11.029] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2004] [Accepted: 11/29/2004] [Indexed: 10/25/2022]
Abstract
Some synthetic ligands of the peripheral-type benzodiazepine receptor (PBR), an 18 kDa protein of the outer mitochondrial membrane, are cytotoxic for several tumor cell lines and arise as promising chemotherapeutic candidates. However, conflicting results were reported regarding the actual effect of these drugs on cellular survival ranging from protection to toxicity. Moreover, the concentrations needed to observe such a toxicity were usually high, far above the affinity range for their receptor, hence questioning its specificity. In the present study, we have shown that micromolar concentrations of FGIN-1-27 and Ro 5-4864, two chemically unrelated PBR ligands are toxic for both PBR-expressing SK-N-BE neuroblastoma cells and PBR-deficient Jurkat lymphoma cells. We have thereby demonstrated that the cytotoxicity of these drugs is unrelated to their PBR-binding activity. Moreover, Ro 5-4864-induced cell death differed strikingly between both cell types, being apoptotic in Jurkat cells while necrotic in SK-N-BE cells. Again, this did not seem to be related to PBR expression since Ro 5-4864-induced death of PBR-transfected Jurkat cells remained apoptotic. Taken together, our results show that PBR is unlikely to mediate all the effects of these PBR ligands. They however confirm that some of these ligands are very effective cytotoxic drugs towards various cancer cells, even for reputed chemoresistant tumors such as neuroblastoma, and, surprisingly, also for PBR-lacking tumor cells.
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Affiliation(s)
- Gregory Hans
- Centre of Cellular and Molecular Neurobiology, Université de Liège, 17 Place Delcour, 4020 Liège 2, Belgium.
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23
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Galiègue S, Casellas P, Kramar A, Tinel N, Simony-Lafontaine J. Immunohistochemical assessment of the peripheral benzodiazepine receptor in breast cancer and its relationship with survival. Clin Cancer Res 2004; 10:2058-64. [PMID: 15041726 DOI: 10.1158/1078-0432.ccr-03-0988] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The peripheral benzodiazepine receptor (PBR) expression has been shown dramatically increased in neoplastic tissues and tumor cell lines originated from ovary, liver, colon, breast, or brain relative to untransformed tissues. Its expression has been also associated with tumor progression and aggressiveness. To explore whether PBR expression level could be of prognostic value in invasive breast cancer, we studied a series of 117 patients who underwent surgery for primary breast carcinomas and were followed-up for 8 years. EXPERIMENTAL DESIGN Using an immunohistochemical approach, we first compared PBR expression in normal and tumoral tissues, then we studied PBR expression together with clinicopathological variables (histological type, histological grade, lymph node, estrogen and progesterone receptor status), and biological markers such as BclII, Ki-67, and HER2/Neu. RESULTS Our results revealed a significant increase of PBR expression in tumoral versus normal breast cells. We found a negative correlation between PBR expression and estrogen receptor status (P = 0.03) as well as a positive correlation between PBR and Ki-67 (P = 0.044). Although the disease-free survival was not affected by PBR in the whole population, high PBR expression level was significantly correlated with a shorter disease-free survival in the lymph node-negative patients, P = 0.038. CONCLUSIONS As the axillary lymph node-negative status is generally considered as a good prognosis factor, the high expression of PBR in this patient subgroup may be used to identify a new high risk population, for which a more specific therapy would be beneficial.
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Affiliation(s)
- Sylvaine Galiègue
- Department of Immunology-Oncology, Sanofi-Synthelabo Recherche, Val d'Aurelle-Paul Lamarque Cancer Institute, Montpellier, France
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24
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Maaser K, Sutter AP, Krahn A, Höpfner M, Grabowski P, Scherübl H. Cell cycle-related signaling pathways modulated by peripheral benzodiazepine receptor ligands in colorectal cancer cells. Biochem Biophys Res Commun 2004; 324:878-86. [PMID: 15474510 DOI: 10.1016/j.bbrc.2004.09.127] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Indexed: 01/17/2023]
Abstract
Specific ligands of the peripheral benzodiazepine receptor (PBR) have been shown to induce both apoptosis and G1/G0 cell cycle arrest in colorectal cancers. The signaling pathways leading to cell cycle arrest are still unknown. Using cDNA array technology, we identified signaling molecules involved in cell cycle arrest induced by the PBR ligands FGIN-1-27 and PK 11195. Differential gene expression was confirmed by semi-quantitative RT-PCR or Western blot analysis of gene products. The PBR ligand-mediated signaling involved the upregulation of the cyclin-dependent kinase inhibitors p21WAF1/CIP1 and p27Kip1, cdc16, and the cell cycle inhibitors gadd45 and gadd153, the downregulation of the cyclins D1 and B1, as well as the inactivation of ERK1/2. The p21-deficient colorectal cancer cell line HCT116 p21-/- was significantly less sensitive to PBR ligands than the parental HCT116 wild-type cells, demonstrating the functional involvement of p21WAF1/CIP1 in PBR ligand-mediated G1 arrest. This study thus revealed PBR ligand-triggered signaling pathways leading to cell cycle arrest. Moreover, we showed the functional implication and interaction of differentially expressed gene products and provided a model of signaling pathways involved in PBR ligand-induced G1 arrest. These results form the basis for future PBR ligand-mediated therapeutic approaches.
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Affiliation(s)
- Kerstin Maaser
- Medical Clinic I, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, 12200 Berlin, Germany
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25
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Abstract
Tumor cell targeted therapies, by induction or enhancement of apoptosis, constitute recent promising approaches achieving more specific anti-tumor efficacy. The peripheral benzodiazepine receptor (PBR), which belongs to the permeability transition pore (PTP), the central regulatory complex of apoptosis, is a potential target. A number of findings argue in favor of the development of PBR targeting approaches: (i) overexpression of PBR has been described in a large range of human cancers, (ii) PTP-mediated regulation of programmed cell death is an apoptotic-inducing factor-independent check-point that could be modulated by various conventional cancer therapies, and (iii) PBR ligation enhances apoptosis induction in many types of tumors and reverses Bcl-2 cytoprotective effects. Altogether, these observations support the use of PBR-directed drugs, particularly PBR ligands such as Ro5-4864, in the treatment of human cancers.
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Affiliation(s)
- Didier Decaudin
- Department of Clinical Hematology, Institut Curie, Paris, France.
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26
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Han Z, Slack RS, Li W, Papadopoulos V. Expression of peripheral benzodiazepine receptor (PBR) in human tumors: relationship to breast, colorectal, and prostate tumor progression. J Recept Signal Transduct Res 2004; 23:225-38. [PMID: 14626449 DOI: 10.1081/rrs-120025210] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
High levels of peripheral-type benzodiazepine receptor (PBR), the alternative-binding site for diazepam, are part of the aggressive human breast cancer cell phenotype in vitro. We examined PBR levels and distribution in normal tissue and tumors from multiple cancer types by immunohistochemistry. Among normal breast tissues, fibroadenomas, primary and metastatic adenocarcinomas, there is a progressive increase in PBR levels parallel to the invasive and metastatic ability of the tumor (p < 0.0001). In colorectal and prostate carcinomas, PBR levels were also higher in tumor than in the corresponding non-tumoral tissues and benign lesions (p < 0.0001). In contrast, PBR was highly concentrated in normal adrenal cortical cells and hepatocytes, whereas in adrenocortical tumors and hepatomas PBR levels were decreased. Moreover, malignant skin tumors showed decreased PBR expression compared with normal skin. These results indicate that elevated PBR expression is not a common feature of aggressive tumors, but rather may be limited to certain cancers, such as those of breast, colon-rectum and prostate tissues, where elevated PBR expression is associated with tumor progression. Thus, we propose that PBR overexpression could serve as a novel prognostic indicator of an aggressive phenotype in breast, colorectal and prostate cancers.
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Affiliation(s)
- Zeqiu Han
- Division of Hormone Research, Department of Cell Biology, Georgetown University Medical Center, Washington, District of Columbia 20057, USA
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27
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Lacapère JJ, Papadopoulos V. Peripheral-type benzodiazepine receptor: structure and function of a cholesterol-binding protein in steroid and bile acid biosynthesis. Steroids 2003; 68:569-85. [PMID: 12957662 DOI: 10.1016/s0039-128x(03)00101-6] [Citation(s) in RCA: 252] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Cholesterol transport from the outer to the inner mitochondrial membrane is the rate-determining step in steroid and bile acid biosyntheses. Biochemical, pharmacological and molecular studies have demonstrated that the peripheral-type benzodiazepine receptor (PBR) is a five transmembrane domain mitochondrial protein involved in the regulation of cholesterol transport. PBR gene disruption in Leydig cells completely blocked cholesterol transport into mitochondria and steroid formation, while PBR expression in bacteria, devoid of endogenous PBR and cholesterol, induced cholesterol uptake and transport. Molecular modeling of PBR suggested that cholesterol might cross the membrane through the five helices of the receptor and that synthetic and endogenous ligands might bind to common sites in the cytoplasmic loops. A cholesterol recognition/interaction amino acid consensus (CRAC) sequence in the cytoplasmic carboxy-terminus of the PBR was identified by mutagenesis studies. In vitro reconstitution of PBR into proteoliposomes demonstrated that PBR binds both drug ligands and cholesterol with high affinity. In vivo polymeric forms of PBR were observed and polymer formation was reproduced in vitro, using recombinant PBR protein reconstituted into proteoliposomes, associated with an increase in drug ligand binding and reduction of cholesterol-binding capacity. This suggests that the various polymeric states of PBR might be part of a cycle mediating cholesterol uptake and release into the mitochondria, with PBR functioning as a cholesterol exchanger against steroid product(s) arising from cytochrome P450 action. Taking into account the widespread presence of PBR in many tissues, a more general role of PBR in intracellular cholesterol transport and compartmentalization might be considered.
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Affiliation(s)
- Jean Jacques Lacapère
- Unité INSERM U410, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, 75870 Paris Cedex 18, France.
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28
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Abstract
A new cell line, designated UHKBR-01, was successfully established from a 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary tumour. DMBA was administered orally at a dose of 4 mg/ml per rat on the first day of the experiment and thereafter at weekly intervals of same dosage, until the rats have reached a weight of around 150-200 g. The tumours grew rapidly after the injection, and were transplanted into nude mice one the harvest size (2.5 x 2 x 1 mm(3)) was reached, it was transplanted onto nude mice. We have developed a cell line from a portion of the DMBA-induced carcinoma of the nude mice. The UHKBR-01 cell exhibited a slow increase in growth rate during the time of culture and was highly tumourigenic in nude mice. The cells have been grown in culture for over 40 passages. Characterization of the cell line was performed. This included morphology by light and transmission electron microscopy, karyotype, growth rate, tumour antigen expression and xenograft implantation into nude mice. These cells exhibit ultrastructural and immunohistochemical features of epithelial cells of mammary origin. The above analyses also demonstrated that UHKBR-01 cells were oestrogen- and progesterone-receptor positive, in likeness to other established breast cancer cell lines such as MDA-MB-231 and MCF-7. The cell line grows as monolayers of oval-shaped cells with large folded nuclei accompanied by a rich supply of mitochondria. This report describes the first in vitro cell line from transplantable DMBA-induced mammary carcinoma of nude mice, which presents unique characteristics that may prove to be a good experimental model for investigating breast cancer biology.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene/toxicity
- Animals
- Antigens, Neoplasm/analysis
- Antineoplastic Agents/pharmacology
- Carcinogens/toxicity
- Female
- Immunohistochemistry
- Karyotyping
- Mammary Neoplasms, Experimental/chemically induced
- Mammary Neoplasms, Experimental/drug therapy
- Mammary Neoplasms, Experimental/pathology
- Mice
- Mice, Nude
- Microscopy, Electron
- Neoplasm Transplantation
- Rats
- Rats, Sprague-Dawley
- Tumor Cells, Cultured
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Affiliation(s)
- Louis W C Chow
- Department of Surgery, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
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29
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Righi L, Deaglio S, Pecchioni C, Gregorini A, Horenstein AL, Bussolati G, Sapino A, Malavasi F. Role of CD31/platelet endothelial cell adhesion molecule-1 expression in in vitro and in vivo growth and differentiation of human breast cancer cells. THE AMERICAN JOURNAL OF PATHOLOGY 2003; 162:1163-74. [PMID: 12651608 PMCID: PMC1851235 DOI: 10.1016/s0002-9440(10)63912-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Breast ductal carcinoma in situ is an intraductal proliferation of malignant epithelial cells that diffuse within the ductal system without stromal invasion. Our finding that a subset of these tumors express CD31/platelet endothelial cell adhesion molecule-1 suggests that breast cancer represents an informative model for studying the involvement of the molecule in the morphogenesis, differentiation, and diffusion of this disease. Transfection of CD31 in MDA-MB-231 cells caused reduction in growth, loss of CD44, and acquisition of a ductal morphology. The same effects were maintained in vivo, in which CD31(+) tumors grew with in situ-like aspects, papillary differentiation, and a secretory phenotype. CD44 was down-modulated, with the CD31(+) cells blocked in the G(1) phase. The morphology was highly similar to what was observed in some human CD31(+) ductal carcinomas in situ. MDA-MB-231 mock cells grew in solid sheets, lacking stromal material, and displaying high levels of CD44 and proliferation. CD31(+) cells acquired motility characteristics in in vitro assays, a finding confirmed in vivo by the diffusion of human tumor cells throughout the normal ducts residual in the murine mammary gland. In conclusion, CD31 expression reverts the undifferentiated morphology and aggressive behavior of MDA-MB-231 cells, indicating its active role in the morphogenesis of breast ductal in situ carcinomas.
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Affiliation(s)
- Luisella Righi
- Department of Genetics, Biology, and Biochemistry, Laboratory of Immunogenetics, University of Torino Medical School, Torino, Italy
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30
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Hardwick M, Cavalli LR, Barlow KD, Haddad BR, Papadopoulos V. Peripheral-type benzodiazepine receptor (PBR) gene amplification in MDA-MB-231 aggressive breast cancer cells. CANCER GENETICS AND CYTOGENETICS 2002; 139:48-51. [PMID: 12547158 DOI: 10.1016/s0165-4608(02)00604-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent studies using human breast cancer cell lines, animal models, and human tissue biopsies have suggested a close correlation between the expression of the peripheral-type benzodiazepine receptor (PBR) and the progression of breast cancer. This study investigates the genetic status of the PBR gene in two human breast cancer cell lines: MDA-MB-231 cells, which are an aggressive breast cancer cell line that contains high levels of PBR, and MCF-7 cells, which are a nonaggressive cell line that contains low levels of PBR. Both DNA (Southern) blot and fluorescence in situ hybridization analyses indicate that the PBR gene is amplified in MDA-MB-231 relative to MCF-7 cells. These data suggest that PBR gene amplification may be an important indicator of breast cancer progression.
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Affiliation(s)
- Matthew Hardwick
- Division of Hormone Research, Department of Cell Biology, Georgetown University Medical Center, Georgetown, Washington DC 20007, USA
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31
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Gazouli M, Yao ZX, Boujrad N, Corton JC, Culty M, Papadopoulos V. Effect of peroxisome proliferators on Leydig cell peripheral-type benzodiazepine receptor gene expression, hormone-stimulated cholesterol transport, and steroidogenesis: role of the peroxisome proliferator-activator receptor alpha. Endocrinology 2002; 143:2571-83. [PMID: 12072389 DOI: 10.1210/endo.143.7.8895] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In this study, we hypothesized that many of the reported effects of phthalate esters and other peroxisome proliferators (PPs) in the testis are mediated by members of the PP- activated receptor (PPAR) family of transcription factors through alterations in proteins involved in steroidogenesis. Exposure of Leydig cells to PPs prevented cholesterol transport into the mitochondria after hormonal stimulation and inhibited steroid synthesis, without altering total cell protein synthesis or mitochondrial and DNA integrity. PPs also reduced the levels of the cholesterol-binding protein peripheral-type benzodiazepine receptor (PBR) because of a direct transcriptional inhibition of PBR gene expression in MA-10 Leydig cells. MA-10 cells contain mRNAs for PPARalpha and PPARbeta/delta, but not for PPARgamma. In vivo treatment of mice with PPs resulted in the reduction of both testis PBR mRNA and circulating testosterone levels, in agreement with the proposed role of PBR in steroidogenesis. By contrast, liver PBR mRNA levels were increased, in agreement with the proposed role of PBR in cell growth/tumor formation in nonsteroidogenic tissues. However, PPs did not inhibit testosterone production and testis PBR expression in PPARalpha-null mice. These results suggest that the antiandrogenic effect of PPs is mediated by a PPARalpha-dependent inhibition of Leydig cell PBR gene expression.
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MESH Headings
- Androgen Antagonists
- Animals
- Biological Transport, Active/drug effects
- Blotting, Northern
- Carrier Proteins/biosynthesis
- Carrier Proteins/genetics
- Catalase/metabolism
- Cell Survival/drug effects
- Cells, Cultured
- Cholesterol/metabolism
- Chorionic Gonadotropin/antagonists & inhibitors
- DNA Damage/drug effects
- Electrophoresis, Polyacrylamide Gel
- Gene Expression Regulation/drug effects
- Humans
- Leydig Cells/drug effects
- Leydig Cells/metabolism
- Male
- Mice
- Mitochondria/drug effects
- Mitochondria/metabolism
- Pancreatic Elastase
- Peroxisome Proliferators/pharmacology
- RNA, Messenger/biosynthesis
- Radioimmunoassay
- Radioligand Assay
- Rats
- Receptors, Cytoplasmic and Nuclear/drug effects
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, GABA-A/biosynthesis
- Receptors, GABA-A/drug effects
- Receptors, GABA-A/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Steroids/biosynthesis
- Transcription Factors/drug effects
- Transcription Factors/metabolism
- Transfection
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Affiliation(s)
- Maria Gazouli
- Division of Hormone Research, Department of Cell Biology, Georgetown University Medical Center, Washington, DC 20007, USA
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