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Mechanism of gadophrin-2 accumulation in tumor necrosis
B Hofmann1, A Bogdanov, E Marecos
1Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown 02129, USA.
Abstract:
The molecular mechanism by which gadophrin-2 targets necrotic tumor tissue was investigated. Biodistribution studies and magnetic resonance imaging (MRI) and histologic/autoradiographic correlation were performed in xenograft mouse models bearing human tumors (HT 29, WiDr, LX 1). Binding of gadophrin-2 to DNA, lipids, or proteins was determined by fluorescence spectrophotometry. Protein binding was determined by dialysis and gel electrophoresis. Accumulation of gadophrin-2 was low (<0.7% injected dose/g tissue at 24 hours after injection) in viable tumor but higher in necrotic tumor regions and was readily detectable by MRI. Within a given tumor, the agent preferentially localized in the periphery of necrotic areas. Within these regions gadophrin-2 was bound to interstitial albumin and not other proteins, lipids, or DNA. Tumoral accumulation of gadophrin-2 most likely occurs through its binding to plasma albumin and subsequent slow extravasation into the tumor interstitium.
Insights
Gadophrin-2 targets necrotic tumor tissue by binding to albumin, not DNA or lipids. This MRI contrast agent accumulates in tumor necrotic regions, aiding detection.
Area of Science:
- Oncology
- Radiology
- Biochemistry
Background:
- Gadophrin-2 is an MRI contrast agent investigated for tumor targeting.
- Understanding its molecular mechanism is crucial for optimizing its clinical application.
Purpose of the Study:
- To elucidate the molecular mechanism of gadophrin-2 targeting in necrotic tumor tissue.
- To determine the binding interactions and accumulation sites of gadophrin-2 within tumors.
Main Methods:
- Biodistribution studies, MRI, and histologic/autoradiographic correlation in xenograft mouse models.
- In vitro binding assays (fluorescence spectrophotometry, dialysis, gel electrophoresis) to assess gadophrin-2 interaction with DNA, lipids, and proteins.
- Quantitative analysis of gadophrin-2 accumulation in viable and necrotic tumor regions.
Main Results:
- Gadophrin-2 showed low accumulation in viable tumor but higher accumulation in necrotic regions, detectable by MRI.
- The agent preferentially localized in the periphery of necrotic areas.
- Gadophrin-2 was found to bind specifically to interstitial albumin within necrotic tumor regions, not other biomolecules.
Conclusions:
- Tumoral accumulation of gadophrin-2 is primarily mediated by its binding to plasma albumin.
- Subsequent slow extravasation of albumin-bound gadophrin-2 into the tumor interstitium facilitates targeting of necrotic areas.
- The findings provide insight into the mechanism of gadophrin-2 tumor targeting for MRI applications.