Near-infrared optical imaging of epidermal growth factor receptor in breast cancer xenografts.
The specificity of a novel epidermal growth factor (EGF)-Cy5.5 fluorescent optical probe in the detection of EGF receptor (EGFr) was assessed using continuous-wave fluorescence imaging accomplished via an intensified charge-coupled device (CCD) camera. Human mammary MDA-MB-468 (EGFr+) and MDA-MB-435 (EGFr-) cancer cells were incubated with Cy5.5, EGF-Cy5.5, or the anti-EGFr monoclonal antibody C225 or EGF followed by EGF-Cy5.5 and examined under a fluorescence microscope. In vivo imaging was performed on mice with s.c. MDA-MB-468 and MDA-MB-435 tumors. Images were obtained every 6 s for 20 min after i.v. injection of each agent and every 24 h after injection for up to 192 h. Additionally, mice with MDA-MB-468 tumors were injected i.v. with C225 24 h before injection of EGF-Cy5.5. EGF-Cy5.5, but not Cy5.5 or indocyanine green dye (ICG), bound to MDA-MB-468 cells. Binding of EGF-Cy5.5 was blocked by C225 and by EGF. In contrast, binding of EGF-Cy5.5 to MDA-MB-435 cells was not observed. Monitoring of the time-fluorescence intensity in mice confirmed that ICG and Cy5.5 had no favorable binding to tumor regardless of EGFr expression level. In contrast, EGF-Cy5.5 accumulated only in MDA-MB-468 tumors. Moreover, tumor uptake of EGF-Cy5.5 was blocked by C225. ICG and Cy5.5 fluorescence was completely absent from the tumor site, regardless of EGFr expression level, 24 h after injection. Little EGF-Cy5.5 fluorescence was detected in MDA-MB-435 tumors 24 h after injection. In MDA-MB-468 tumors, our data suggest that EGF-Cy5.5 may be used as a specific NIR contrast agent for noninvasive imaging of EGFr expression and monitoring of responses to molecularly targeted therapy.
Ke
Shi
S
Division of Diagnostic Imaging, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
Wen
Xiaoxia
X
Gurfinkel
Michael
M
Charnsangavej
Chusilp
C
Wallace
Sidney
S
Sevick-Muraca
Eva M
EM
Li
Chun
C
D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002232:Carbocyanines / Q000378:metabolism* / Q000493:pharmacokinetics; D045744:Cell Line, Tumor; D004815:Epidermal Growth Factor / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D005456:Fluorescent Dyes / Q000378:metabolism* / Q000493:pharmacokinetics; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D019265:Spectroscopy, Near-Infrared / Q000379:methods; D013379:Substrate Specificity; D014183:Transplantation, Heterologous
C098793:CY5.5 cyanine dye; D002232:Carbocyanines; D005456:Fluorescent Dyes; D004815:Epidermal Growth Factor; D066246:ErbB Receptors