Molecular imaging of the translocator protein (TSPO) in a pre-clinical model of breast cancer.
OBJECTIVE
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.


METHODS
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.
Wyatt
Shelby K
SK
Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.
Manning
H Charles
HC
Bai
Mingfeng
M
Bailey
Stephanie N
SN
Gallant
Pascal
P
Ma
Guobin
G
McIntosh
Laura
L
Bornhop
Darryl J
DJ
D000818:Animals; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D057054:Molecular Imaging / Q000379:methods*; D015335:Molecular Probes / Q000737:chemistry / Q000493:pharmacokinetics; D018079:Receptors, GABA / Q000378:metabolism*; D019265:Spectroscopy, Near-Infrared; D013997:Time Factors; D014018:Tissue Distribution; D051598:Whole Body Imaging
D015335:Molecular Probes; D018079:Receptors, GABA; C499229:TSPO protein, human