An enzymatically activated fluorescence probe for targeted tumor imaging.
Beta-galactosidase is a widely used reporter enzyme, but although several substrates are available for in vitro detection, its application for in vivo optical imaging remains a challenge. To obtain a probe suitable for in vivo use, we modified our previously developed activatable fluorescence probe, TG-betaGal (J. Am. Chem. Soc. 2005, 127, 4888-4894), on the basis of photochemical and photophysical experiments. The new probe, AM-TG-betaGal, provides a dramatic fluorescence enhancement upon reaction with beta-galactosidase, and further hydrolysis of the ester moiety by ubiquitous intracellular esterases affords a hydrophilic product that is well retained within the cells without loss of fluorescence. We used a mouse tumor model to assess the practical utility of AM-TG-betaGal, after confirming that tumors in the model could be labeled with an avidin-beta-galactosidase conjugate. This conjugate was administered to the mice in vivo, followed by AM-TG-betaGal, and subsequent ex vivo fluorescence imaging clearly visualized intraperitoneal tumors as small as 200 microm. This strategy has potential clinical application, for example, in video-assisted laparoscopic tumor resection.
Kamiya
Mako
M
Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Kobayashi
Hisataka
H
Hama
Yukihiro
Y
Koyama
Yoshinori
Y
Bernardo
Marcelino
M
Nagano
Tetsuo
T
Choyke
Peter L
PL
Urano
Yasuteru
Y
D000818:Animals; D002460:Cell Line; D004950:Esterases / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D051379:Mice; D015394:Molecular Structure; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000201:enzymology* / Q000473:pathology*; D010084:Oxidation-Reduction; D013552:Swine; D001616:beta-Galactosidase / Q000378:metabolism*
D005456:Fluorescent Dyes; D004950:Esterases; D001616:beta-Galactosidase