Sun Xiankai, Fang Huafeng, Li Xiaoxu, Rossin Raffaella, Welch Michael J, Taylor John-Stephen
Division of Radiological Sciences, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Bioconjug Chem. 2005 Mar-Apr;16(2):294-305. doi: 10.1021/bc049783u.
As more becomes known about the expression profiles of normal and cancerous cells, it should become possible to design antisense-based imaging agents for the early detection of cancer noninvasively. In this report, we rationally designed and synthesized three antisense and one sense hybrid PNA (peptide nucleic acid) to the unr mRNA that is highly overexpressed in a breast cancer cell line (MCF-7). The conjugates had a four-lysine tail at the carboxy terminus for cell permeation and a DOTA (1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) chelating moiety at the amino terminal end for chelating (64)Cu for biodistribution and microPET imaging studies. Biodistribution of two (64)Cu-labeled conjugates with antisense and sense sequences (PNA50 and PNA50S) showed high uptake and long retention in kidney and low uptake and efficient clearance in blood and muscle in normal balb/c mice when administered intravenously or intraperitoneally. Intraperitoneal administration, however, gave a much slower release rate. MCF-7 tumors (100-320 mg) in CB-17 SCID mice were imaged with all four (64)Cu-labeled PNA conjugates by microPET, but the image contrast varied with different time points and different conjugates. Of the conjugates studied, (64)Cu-DOTA-Y-PNA50-K4 showed the best tumor image quality at all time points with a tumor/muscle ratio of 6.6 +/- 1.1 at 24 h postinjection, which is among the highest reported for radiolabeled oligonucleotides. Our work further strengthens the potential of antigene and antisense PNAs to be utilized as specific molecular probes for early detection of cancer and ultimately for patient specific radiotherapy.
随着对正常细胞和癌细胞表达谱的了解越来越多，设计基于反义的成像剂以实现癌症的早期无创检测应该成为可能。在本报告中，我们合理设计并合成了三种针对在乳腺癌细胞系（MCF-7）中高度过表达的unr mRNA的反义及一种正义杂交肽核酸（PNA）。这些缀合物在羧基末端有一个四赖氨酸尾巴用于细胞渗透，在氨基末端有一个DOTA（1,4,7,10-四氮杂环十二烷-N,N',N'',N'''-四乙酸）螯合部分用于螯合（64）Cu以进行生物分布和微型PET成像研究。两种具有反义及正义序列（PNA50和PNA50S）的（64）Cu标记缀合物在正常的balb/c小鼠中静脉内或腹腔内给药后，其生物分布显示在肾脏中有高摄取和长滞留，而在血液和肌肉中有低摄取和有效清除。然而，腹腔内给药的释放速率要慢得多。通过微型PET对CB-17 SCID小鼠中的MCF-7肿瘤（100 - 320 mg）用所有四种（64）Cu标记的PNA缀合物进行成像，但图像对比度随不同时间点和不同缀合物而变化。在所研究的缀合物中，（64）Cu-DOTA-Y-PNA50-K4在所有时间点都显示出最佳的肿瘤图像质量，在注射后24小时肿瘤/肌肉比为6.6±1.1，这是放射性标记寡核苷酸报道的最高值之一。我们的工作进一步加强了抗原和反义PNA作为癌症早期检测以及最终用于患者特异性放疗的特异性分子探针的潜力。
