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Repetitive, noninvasive imaging of cyclooxygenase-2 gene expression in living mice
Julie T Nguyen1, Hidevaldo Machado, Harvey R Herschman
1Department of Biological Chemistry, Molecular Biology Institute, David Geffen School of Medicine, Los Angeles, CA, USA.
Abstract:
The cyclooxygenase-2 (COX-2) gene plays a role in a wide variety of normal physiologic pathways and is a major target of pharmacologic intervention in a large number of pathophysiologic contexts, including pain, fever, inflammation, and cancer. Expression of the COX-2 gene is induced in a wide range of cells, in response to an ever-increasing number of stimuli. The regulation of the COX-2 gene has been the subject of extensive study, using traditional transfection techniques with reporter gene constructs. Regulation of the COX-2 gene in living animals, however, requires sacrifice of the animal and in situ hybridization and/or immunohistochemical studies. We have utilized in vivo optical imaging technology with a cooled charged coupled device camera to image the expression of the firefly luciferase gene in tumor xenografts that are stably transfected with a chimeric gene containing the first kilobase of the murine COX-2 promoter. Induction of luciferase gene expression following systemic lipopolysaccharide/endotoxin administration can be robustly demonstrated; both a dose-response relationship and a time course for luciferase expression from the COX-2 promoter can be noninvasively analyzed in the tumor xenografts. These data suggest expression from the COX-2 promoter will be easily analyzed in transgenic mice, in knock-in mice, and in somatic cell and gene transfer experiments.
Insights
Researchers developed a non-invasive method to study cyclooxygenase-2 (COX-2) gene expression in living animals. This new technique uses in vivo optical imaging to track luciferase gene activity, offering a significant advancement for studying inflammation and cancer.
Area of Science:
- Molecular Biology
- Biomedical Imaging
- Genetics
Background:
- Cyclooxygenase-2 (COX-2) is crucial in physiological pathways and targeted in treating pain, fever, inflammation, and cancer.
- COX-2 gene expression is induced by various stimuli across numerous cell types.
- Traditional methods for studying COX-2 regulation in vivo require animal sacrifice and invasive techniques.
Purpose of the Study:
- To develop a non-invasive method for analyzing COX-2 gene regulation in living animals.
- To utilize in vivo optical imaging to monitor COX-2 promoter activity.
- To establish a system for real-time assessment of COX-2 gene induction.
Main Methods:
- Utilized in vivo optical imaging with a cooled CCD camera.
- Created tumor xenografts stably transfected with a chimeric gene (murine COX-2 promoter driving luciferase).
- Administered lipopolysaccharide/endotoxin systemically to induce gene expression.
Main Results:
- Successfully imaged firefly luciferase gene expression driven by the COX-2 promoter in tumor xenografts.
- Demonstrated robust induction of luciferase expression upon lipopolysaccharide/endotoxin administration.
- Established non-invasive analysis of dose-response and time-course for COX-2 promoter activity.
Conclusions:
- In vivo optical imaging provides a powerful, non-invasive tool for studying COX-2 gene regulation.
- This method facilitates analysis in various models, including transgenic, knock-in, and gene transfer experiments.
- The findings pave the way for advanced research into COX-2 related pathologies.
