Newton-Northup Jessica R, Figueroa Said D, Quinn Thomas P, Deutscher Susan L
Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA.
Nucl Med Biol. 2009 Oct;36(7):789-800. doi: 10.1016/j.nucmedbio.2009.04.010. Epub 2009 Jul 9.
Two-step and three-step pretargeting systems utilizing biotinylated prostate tumor-homing bacteriophage (phage) and (111)In-radiolabeled streptavidin or biotin were developed for use in cancer radioimaging. The in vivo selected prostate carcinoma-specific phage (G1) displaying up to five copies of the peptide IAGLATPGWSHWLAL was the focus of the present study.
The ability of G1 phage to extravasate and target prostate tumor cells was investigated using immunohistochemistry. G1 phages were biotinylated, streptavidin was conjugated to diethylenetriaminepentaacetic acid (DTPA) and biotin was conjugated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). Biodistribution studies and single-photon emission computed tomography (SPECT)/CT imaging of xenografted PC-3 tumors via two-step pretargeted (111)In-labeled streptavidin and three-step pretargeted (111)In-labeled biotin were performed in SCID mice to determine the optimal pretargeting method.
The ability of G1 phage to extravasate the vasculature and bind directly to human PC-3 prostate carcinoma tumor cells in vivo was demonstrated via immunocytochemical analysis. Comparative biodistribution studies of the two-step and three-step pretargeting strategies indicated increased PC-3 human prostate carcinoma tumor uptake in SCID mice of 4.34+/-0.26 %ID g(-1) at 0.5 h postinjection of (111)In-radiolabeled biotin (utilized in a three-step protocol) compared to 0.67+/-0.06 %ID g(-1) at 24 h postinjection of (111)In radiolabeled streptavidin (employed in a two-step protocol). In vivo SPECT/CT imaging of xenografted PC-3 tumors in SCID mice with the three-step pretargeting method was superior to that of the two-step pretargeting method, and, importantly, blocking studies demonstrated specificity of tumor uptake of (111)In-labeled biotin in the three-step pretargeting scheme.
This study demonstrates the use of multivalent bifunctional phage in a three-step pretargeting system for prostate cancer radioimaging.
开发了利用生物素化的前列腺肿瘤归巢噬菌体（噬菌体）以及（111）铟标记的链霉亲和素或生物素的两步和三步预靶向系统，用于癌症放射性成像。本研究聚焦于体内筛选出的前列腺癌特异性噬菌体（G1），其展示多达五个拷贝的肽IAGLATPGWSHWLAL。
采用免疫组织化学研究G1噬菌体渗出和靶向前列腺肿瘤细胞的能力。对G1噬菌体进行生物素化，将链霉亲和素与二乙烯三胺五乙酸（DTPA）偶联，将生物素与1,4,7,10 - 四氮杂环十二烷 - 1,4,7,10 - 四乙酸（DOTA）偶联。通过两步预靶向（111）铟标记的链霉亲和素和三步预靶向（111）铟标记的生物素，在严重联合免疫缺陷（SCID）小鼠中进行异种移植PC - 3肿瘤的生物分布研究和单光子发射计算机断层扫描（SPECT）/计算机断层扫描（CT）成像，以确定最佳预靶向方法。
通过免疫细胞化学分析证明了G1噬菌体在体内渗出脉管系统并直接结合人PC - 3前列腺癌细胞的能力。两步和三步预靶向策略的比较生物分布研究表明，在注射（111）铟标记的生物素（用于三步方案）后0.5小时，SCID小鼠中PC - 3人前列腺癌肿瘤摄取增加至4.34±0.26 %ID/g（-1），相比之下，注射（111）铟标记的链霉亲和素（用于两步方案）后24小时为0.67±0.06 %ID/g（-1）。采用三步预靶向方法对SCID小鼠体内异种移植的PC - 3肿瘤进行的体内SPECT/CT成像优于两步预靶向方法，重要的是，阻断研究证明了三步预靶向方案中（111）铟标记的生物素肿瘤摄取的特异性。
本研究证明了多价双功能噬菌体在用于前列腺癌放射性成像的三步预靶向系统中的应用。
