1
|
Dragulescu-Andrasi A, Kothapalli SR, Tikhomirov GA, Rao J, Gambhir SS. Activatable oligomerizable imaging agents for photoacoustic imaging of furin-like activity in living subjects. J Am Chem Soc 2013; 135:11015-22. [PMID: 23859847 DOI: 10.1021/ja4010078] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photoacoustic (PA) imaging is continuing to be applied for physiological imaging and more recently for molecular imaging of living subjects. Owing to its high spatial resolution in deep tissues, PA imaging holds great potential for biomedical applications and molecular diagnostics. There is however a lack of probes for targeted PA imaging, especially in the area of enzyme-activatable probes. Here we introduce a molecular probe, which upon proteolytic processing is retained at the site of enzyme activity and provides PA contrast. The probe oligomerizes via a condensation reaction and accumulates in cells and tumors that express the protease. We demonstrate that this probe reports furin and furin-like activity in cells and tumor models by generating a significantly higher PA signal relative to furin-deficient and nontarget controls. This probe could report enzyme activity in living subjects at depths significantly greater than fluorescence imaging probes and has potential for molecular imaging in deep tumors.
Collapse
Affiliation(s)
- Anca Dragulescu-Andrasi
- Molecular Imaging Program at Stanford and Bio-X Program, Stanford University School of Medicine, Stanford, California 94305, USA
| | | | | | | | | |
Collapse
|
2
|
Levi J, Kothapalli SR, Bohndiek S, Yoon JK, Dragulescu-Andrasi A, Nielsen C, Tisma A, Bodapati S, Gowrishankar G, Yan X, Chan C, Starcevic D, Gambhir SS. Molecular photoacoustic imaging of follicular thyroid carcinoma. Clin Cancer Res 2013; 19:1494-502. [PMID: 23349314 DOI: 10.1158/1078-0432.ccr-12-3061] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
PURPOSE To evaluate the potential of targeted photoacoustic imaging as a noninvasive method for detection of follicular thyroid carcinoma. EXPERIMENTAL DESIGN We determined the presence and activity of two members of matrix metalloproteinase family (MMP), MMP-2 and MMP-9, suggested as biomarkers for malignant thyroid lesions, in FTC133 thyroid tumors subcutaneously implanted in nude mice. The imaging agent used to visualize tumors was MMP-activatable photoacoustic probe, Alexa750-CXeeeeXPLGLAGrrrrrXK-BHQ3. Cleavage of the MMP-activatable agent was imaged after intratumoral and intravenous injections in living mice optically, observing the increase in Alexa750 fluorescence, and photoacoustically, using a dual-wavelength imaging method. RESULTS Active forms of both MMP-2 and MMP-9 enzymes were found in FTC133 tumor homogenates, with MMP-9 detected in greater amounts. The molecular imaging agent was determined to be activated by both enzymes in vitro, with MMP-9 being more efficient in this regard. Both optical and photoacoustic imaging showed significantly higher signal in tumors of mice injected with the active agent than in tumors injected with the control, nonactivatable, agent. CONCLUSIONS With the combination of high spatial resolution and signal specificity, targeted photoacoustic imaging holds great promise as a noninvasive method for early diagnosis of follicular thyroid carcinomas.
Collapse
Affiliation(s)
- Jelena Levi
- Canary Center at Stanford for Cancer Early Detection, Stanford University, Palo Alto, California 94305, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
3
|
Van de Sompel D, Sasportas LS, Dragulescu-Andrasi A, Bohndiek S, Gambhir SS. Improving image quality by accounting for changes in water temperature during a photoacoustic tomography scan. PLoS One 2012; 7:e45337. [PMID: 23071512 PMCID: PMC3469660 DOI: 10.1371/journal.pone.0045337] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 08/21/2012] [Indexed: 11/19/2022] Open
Abstract
The emerging field of photoacoustic tomography is rapidly evolving with many new system designs and reconstruction algorithms being published. Many systems use water as a coupling medium between the scanned object and the ultrasound transducers. Prior to a scan, the water is heated to body temperature to enable small animal imaging. During the scan, the water heating system of some systems is switched off to minimize the risk of bubble formation, which leads to a gradual decrease in water temperature and hence the speed of sound. In this work, we use a commercially available scanner that follows this procedure, and show that a failure to model intra-scan temperature decreases as small as 1.5°C leads to image artifacts that may be difficult to distinguish from true structures, particularly in complex scenes. We then improve image quality by continuously monitoring the water temperature during the scan and applying variable speed of sound corrections in the image reconstruction algorithm. While upgrading to an air bubble-free heating pump and keeping it running during the scan could also solve the changing temperature problem, we show that a software correction for the temperature changes provides a cost-effective alternative to a hardware upgrade. The efficacy of the software corrections was shown to be consistent across objects of widely varying appearances, namely physical phantoms, ex vivo tissue, and in vivo mouse imaging. To the best of our knowledge, this is the first study to demonstrate the efficacy of modeling temporal variations in the speed of sound during photoacoustic scans, as opposed to spatial variations as focused on by previous studies. Since air bubbles pose a common problem in ultrasonic and photoacoustic imaging systems, our results will be useful to future small animal imaging studies that use scanners with similarly limited heating units.
Collapse
Affiliation(s)
| | | | | | | | - Sanjiv Sam Gambhir
- Molecular Imaging Program at Stanford (MIPS), Stanford University School of Medicine, Stanford University, Stanford, California, United States of America
- * E-mail:
| |
Collapse
|
4
|
Conley NR, Dragulescu-Andrasi A, Rao J, Moerner WE. A selenium analogue of firefly D-luciferin with red-shifted bioluminescence emission. Angew Chem Int Ed Engl 2012; 51:3350-3. [PMID: 22344705 PMCID: PMC3494413 DOI: 10.1002/anie.201105653] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 01/18/2012] [Indexed: 01/16/2023]
Abstract
A selenium analogue of amino-D-luciferin, aminoseleno-D-luciferin, is synthesized and shown to be a competent substrate for the firefly luciferase enzyme. It has a red-shifted bioluminescence emission maximum at 600 nm and is suitable for bioluminescence imaging studies in living subjects.
Collapse
|
5
|
Conley NR, Dragulescu-Andrasi A, Rao J, Moerner WE. A Selenium Analogue of Firefly D-Luciferin with Red-Shifted Bioluminescence Emission. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201105653] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
6
|
Xia Z, Xing Y, Jeon J, Kim YP, Gall J, Dragulescu-Andrasi A, Gambhir SS, Rao J. Immobilizing reporters for molecular imaging of the extracellular microenvironment in living animals. ACS Chem Biol 2011; 6:1117-26. [PMID: 21830814 PMCID: PMC3199358 DOI: 10.1021/cb200135e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We report here an immobilization strategy using a collagen binding protein to deliver and confine synthetic reporters to the extracellular microenvironment in vivo for noninvasively imaging the activity of targets in the microenvironment. We show that the immobilization of reporters on collagens in the local microenvironment is highly efficient and physiologically stable for repetitive, long-term imaging. By using this strategy we successfully developed an immobilized bioluminescent activatable reporter and a dual-modality reporter to map and quantitatively image the activity of extracellular matrix metalloproteinases (MMP) in tumor-bearing mice. The inhibition of MMP activity by chemical inhibitor was also demonstrated in living subjects. We further demonstrated the general applicability of this immobilization strategy by imaging MMP activity at the inflammation site in a mouse model. Our results show that the in vivo immobilization of reporters can be used as a general strategy for probing the local extracellular microenvironment.
Collapse
Affiliation(s)
- Zuyong Xia
- Molecular Imaging Program at Stanford, Department of Radiology & Bio-X Program, Stanford University, 1201 Welch Road, Stanford, CA 94035-5484, USA
| | - Yun Xing
- Molecular Imaging Program at Stanford, Department of Radiology & Bio-X Program, Stanford University, 1201 Welch Road, Stanford, CA 94035-5484, USA
| | - Jongho Jeon
- Molecular Imaging Program at Stanford, Department of Radiology & Bio-X Program, Stanford University, 1201 Welch Road, Stanford, CA 94035-5484, USA
| | - Young-Pil Kim
- Molecular Imaging Program at Stanford, Department of Radiology & Bio-X Program, Stanford University, 1201 Welch Road, Stanford, CA 94035-5484, USA
| | - Jessica Gall
- Molecular Imaging Program at Stanford, Department of Radiology & Bio-X Program, Stanford University, 1201 Welch Road, Stanford, CA 94035-5484, USA
| | - Anca Dragulescu-Andrasi
- Molecular Imaging Program at Stanford, Department of Radiology & Bio-X Program, Stanford University, 1201 Welch Road, Stanford, CA 94035-5484, USA
| | - Sanjiv S. Gambhir
- Molecular Imaging Program at Stanford, Department of Radiology & Bio-X Program, Stanford University, 1201 Welch Road, Stanford, CA 94035-5484, USA
- Department of Bioengineering, Stanford University, 1201 Welch Road, Stanford, CA 94035-5484, USA
- Department of Materials Science and Engineering, Stanford University, 1201 Welch Road, Stanford, CA 94035-5484, USA
| | - Jianghong Rao
- Molecular Imaging Program at Stanford, Department of Radiology & Bio-X Program, Stanford University, 1201 Welch Road, Stanford, CA 94035-5484, USA
- Department of Chemistry, Stanford University, 1201 Welch Road, Stanford, CA 94035-5484, USA
- Biophysics and Cancer Biology Programs, Stanford University, 1201 Welch Road, Stanford, CA 94035-5484, USA
| |
Collapse
|
7
|
Dragulescu-Andrasi A, Chan CT, De A, Massoud TF, Gambhir SS. Bioluminescence resonance energy transfer (BRET) imaging of protein-protein interactions within deep tissues of living subjects. Proc Natl Acad Sci U S A 2011; 108:12060-5. [PMID: 21730157 PMCID: PMC3141927 DOI: 10.1073/pnas.1100923108] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Identifying protein-protein interactions (PPIs) is essential for understanding various disease mechanisms and developing new therapeutic approaches. Current methods for assaying cellular intermolecular interactions are mainly used for cells in culture and have limited use for the noninvasive assessment of small animal disease models. Here, we describe red light-emitting reporter systems based on bioluminescence resonance energy transfer (BRET) that allow for assaying PPIs both in cell culture and deep tissues of small animals. These BRET systems consist of the recently developed Renilla reniformis luciferase (RLuc) variants RLuc8 and RLuc8.6, used as BRET donors, combined with two red fluorescent proteins, TagRFP and TurboFP635, as BRET acceptors. In addition to the native coelenterazine luciferase substrate, we used the synthetic derivative coelenterazine-v, which further red-shifts the emission maxima of Renilla luciferases by 35 nm. We show the use of these BRET systems for ratiometric imaging of both cells in culture and deep-tissue small animal tumor models and validate their applicability for studying PPIs in mice in the context of rapamycin-induced FK506 binding protein 12 (FKBP12)-FKBP12 rapamycin binding domain (FRB) association. These red light-emitting BRET systems have great potential for investigating PPIs in the context of drug screening and target validation applications.
Collapse
Affiliation(s)
- Anca Dragulescu-Andrasi
- Molecular Imaging Program at Stanford, Bio-X Program and Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Carmel T. Chan
- Molecular Imaging Program at Stanford, Bio-X Program and Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Abhijit De
- The Advanced Centre for Treatment, Research and Education in Cancer, Tata Memorial Centre, Kharghar, Navi Mumbai 410210, India
| | - Tarik F. Massoud
- Molecular Imaging Program at Stanford, Bio-X Program and Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305
- Department of Radiology and Department of Oncology, University of Cambridge School of Clinical Medicine, Cambridge CB2 2QQ, United Kingdom; and
| | - Sanjiv S. Gambhir
- Molecular Imaging Program at Stanford, Bio-X Program and Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305
- Department of Bioengineering and Department of Materials Science and Engineering, Stanford University School of Medicine, Stanford, CA 94305
| |
Collapse
|
8
|
Lee J, Lee KH, Jeon J, Dragulescu-Andrasi A, Xiao F, Rao J. Combining SELEX screening and rational design to develop light-up fluorophore-RNA aptamer pairs for RNA tagging. ACS Chem Biol 2010; 5:1065-74. [PMID: 20809562 DOI: 10.1021/cb1001894] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We report here a new small molecule fluorogen and RNA aptamer pair for RNA labeling. The small-molecule fluorogen is designed on the basis of fluorescently quenched sulforhodamine dye. The SELEX (Systematic Evolution of Ligands by EXponential enrichment) procedure and fluorescence screening in E. coli have been applied to discover the aptamer that can specifically activate the fluorogen with micromolar binding affinity. The systematic mutation and truncation study on the aptamer structure determined the minimum binding domain of the aptamer. A series of rationally modified fluorogen analogues have been made to probe the interacting groups of fluorogen with the aptamer. These results led to the design of a much improved fluorogen ASR 7 that displayed a 33-fold increase in the binding affinity for the selected aptamer in comparison to the original ASR 1 and an 88-fold increase in the fluorescence emission after the aptamer binding. This study demonstrates the value of combining in vitro SELEX and E. coli fluorescence screening with rational modifications in discovering and optimizing new fluorogen-RNA aptamer labeling pairs.
Collapse
Affiliation(s)
| | - Kyung Hyun Lee
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology
| | - Jongho Jeon
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology
| | | | - Fei Xiao
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology
| | - Jianghong Rao
- Department of Chemistry
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology
| |
Collapse
|
9
|
Loening AM, Dragulescu-Andrasi A, Gambhir SS. A red-shifted Renilla luciferase for transient reporter-gene expression. Nat Methods 2010; 7:5-6. [PMID: 20038949 DOI: 10.1038/nmeth0110-05] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
10
|
Dragulescu-Andrasi A, Liang G, Rao J. In vivo bioluminescence imaging of furin activity in breast cancer cells using bioluminogenic substrates. Bioconjug Chem 2009; 20:1660-6. [PMID: 19642690 DOI: 10.1021/bc9002508] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Furin, a proprotein convertases family endoprotease, processes numerous physiological substrates and is overexpressed in cancer and inflammatory conditions. Noninvasive imaging of furin activity will offer a valuable tool to probe furin function over the course of tumor growth and migration in the same animals in real time and directly assess the inhibition efficacy of drugs in vivo. Here, we report successful bioluminescence imaging of furin activity in xenografted MBA-MB-468 breast cancer tumors in mice with bioluminogenic probes. The probes are conjugates of furin substrate, a consensus amino acid motif R-X-K/R-R (X, any amino acid), with the firefly luciferase substrate D-aminoluciferin. In the presence of the luciferase reporter, the probes are unable to produce bioluminescent emission without furin activation. Blocking experiments with a furin inhibitor and control experiments with a scrambled probe showed that the bioluminescence emission in the presence of firefly luciferase is furin-dependent and specific. After furin activation, a 30-fold increase in the bioluminescent emission was observed in vitro, and on average, a 7-8-fold contrast between the probe and control was seen in the same tumor xenografts in mice. Direct imaging of furin activity may facilitate the study of furin function in tumorigenicity and the discovery of new drugs for furin-targeted cancer therapy.
Collapse
Affiliation(s)
- Anca Dragulescu-Andrasi
- Department of Radiology, Stanford University School of Medicine, Stanford, California 94305, USA
| | | | | |
Collapse
|
11
|
Affiliation(s)
- Anca Dragulescu-Andrasi
- Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305-5484, USA
| | | |
Collapse
|
12
|
Dragulescu-Andrasi A, Rapireddy S, Frezza BM, Gayathri C, Gil RR, Ly DH. A simple gamma-backbone modification preorganizes peptide nucleic acid into a helical structure. J Am Chem Soc 2007; 128:10258-67. [PMID: 16881656 DOI: 10.1021/ja0625576] [Citation(s) in RCA: 212] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Peptide nucleic acid (PNA) is a synthetic analogue of DNA and RNA, developed more than a decade ago in which the naturally occurring sugar phosphate backbone has been replaced by the N-(2-aminoethyl) glycine units. Unlike DNA or RNA in the unhybridized state (single strand) which can adopt a helical structure through base-stacking, although highly flexible, PNA does not have a well-defined conformational folding in solution. Herein, we show that a simple backbone modification at the gamma-position of the N-(2-aminoethyl) glycine unit can transform a randomly folded PNA into a helical structure. Spectroscopic studies showed that helical induction occurs in the C- to N-terminal direction and is sterically driven. This finding has important implication not only on the future design of nucleic acid mimics but also on the design of novel materials, where molecular organization and efficient electronic coupling are desired.
Collapse
Affiliation(s)
- Anca Dragulescu-Andrasi
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, USA
| | | | | | | | | | | |
Collapse
|
13
|
Dragulescu-Andrasi A, Rapireddy S, He G, Bhattacharya B, Hyldig-Nielsen JJ, Zon G, Ly DH. Cell-permeable peptide nucleic acid designed to bind to the 5'-untranslated region of E-cadherin transcript induces potent and sequence-specific antisense effects. J Am Chem Soc 2007; 128:16104-12. [PMID: 17165763 DOI: 10.1021/ja063383v] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Establishing a general and effective method for regulating gene expression in mammalian systems is important for many aspects of biological and biomedical research. Herein we report the antisense activities of a cell-permeable, guanidine-based peptide nucleic acid (PNA) called GPNA. We show that a GPNA oligomer designed to bind to the transcriptional start-site of human E-cadherin gene induces potent and sequence-specific antisense effects and is less toxic to the cells than the corresponding PNA-polyarginine conjugate. GPNA confers its silencing effect by blocking protein translation. The findings reported in this study provide a molecular framework for designing the next generation cell-permeable nucleic acid mimics for regulating gene expression in live cells and intact organisms.
Collapse
|
14
|
Zhou P, Dragulescu-Andrasi A, Bhattacharya B, O'Keefe H, Vatta P, Hyldig-Nielsen JJ, Ly DH. Synthesis of cell-permeable peptide nucleic acids and characterization of their hybridization and uptake properties. Bioorg Med Chem Lett 2006; 16:4931-5. [PMID: 16809033 DOI: 10.1016/j.bmcl.2006.06.052] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 06/13/2006] [Accepted: 06/14/2006] [Indexed: 11/16/2022]
Abstract
Guanidine-based peptide nucleic acid (GPNA) monomers and oligomers containing all four natural (adenine (A), cytosine (C), guanine (G), and thymine (T)) and two unnatural (2-thiouracil (sU) and 2,6-diaminopurine (D)) nucleobases have been synthesized. Thermal denaturation study showed that GPNA oligomers containing alternate D-backbone configuration bind sequence-specifically to DNA and, when incubated with mammalian cells, localized specifically to the endoplasmic reticulum (ER).
Collapse
Affiliation(s)
- Peng Zhou
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
| | | | | | | | | | | | | |
Collapse
|
15
|
Dragulescu-Andrasi A, Zhou P, He G, Ly DH. Cell-permeable GPNA with appropriate backbone stereochemistry and spacing binds sequence-specifically to RNA. Chem Commun (Camb) 2004:244-6. [PMID: 15724200 DOI: 10.1039/b412522c] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Guanidine-based peptide nucleic acid (GPNA) with a d-backbone configuration and alternate spacing binds sequence-specifically to RNA and is readily taken up by both human somatic and embryonic stem (ES) cells.
Collapse
Affiliation(s)
- Anca Dragulescu-Andrasi
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
| | | | | | | |
Collapse
|