National Institute of Biomedical Imaging and Bioengineering, NIH, Bethesda, MD, USA.
Clin Cancer Res. 2010 Aug 15;16(16):4268-77. doi: 10.1158/1078-0432.CCR-10-0968. Epub 2010 Jun 22.
Osteosarcoma represents the most common malignant primary bone tumor in childhood; however, the survival rate has remained unchanged for the past 20 years. To improve existing diagnosis and treatment methods and broaden the spectrum of imaging agents that can be used for early detection and assessment of tumor response to therapy, we performed a phage display-based screening for peptide sequences that bind specifically to osteosarcoma cells.
From the Ph.D.-12 phage display peptide library composed of 2.7 x 10(9) different displayed peptides, one peptide was enriched after four rounds of in vitro selection in 143B osteosarcoma tumor cells with 293T human embryonic kidney cells as a control. Both the peptide and the phage clone displaying the peptide were conjugated with fluorescent dyes for in vitro cell and ex vivo tumor tissue stainings. The peptide was further labeled with (18)F for positron emission tomography imaging studies. Cell uptake and efflux and ex vivo biodistribution were also done with (18)F-labeled osteosarcoma specific peptide.
ASGALSPSRLDT was the dominant sequence isolated from biopanning and named as OSP-1. OSP-1 shares a significant homology with heparinase II/III family protein, which binds and reacts with heparan sulfate proteoglycans. The fluorescence staining showed that FITC-OSP-1-phage or Cy5.5-OSP-1 had high binding with a panel of osteosarcoma cell lines, much less binding with UM-SCC1 human head and neck squamous cell carcinoma cells, and almost no binding with 293T cells, whereas the scrambled peptide OSP-S had virtually no binding to all the cell lines. (18)F-OSP-1 had significantly higher accumulation in 143B tumor cells both in vitro and in vivo than (18)F-OSP-S. (18)F-OSP-1 also had higher uptake in 143B tumors than in UM-SCC-1 tumors.
Our data suggest that OSP-1 peptide is osteosarcoma specific, and the binding site of OSP-1 might be related to heparan sulfate proteoglycans. Appropriately labeled OSP-1 peptide has the potential to serve as a novel probe for osteosarcoma imaging.
骨肉瘤是儿童中最常见的恶性原发性骨肿瘤；然而，在过去的 20 年中，生存率并没有改变。为了改进现有的诊断和治疗方法，并拓宽可用于早期检测和评估肿瘤对治疗反应的成像剂谱，我们进行了基于噬菌体展示的筛选，以寻找特异性结合骨肉瘤细胞的肽序列。
从由 2.7 x 10(9)个不同展示肽组成的 Ph.D.-12 噬菌体展示肽文库中，用 293T 人胚肾细胞作为对照，在 143B 骨肉瘤肿瘤细胞中经过四轮体外选择，富集了一个肽。肽和展示该肽的噬菌体克隆都用荧光染料进行了体外细胞和离体肿瘤组织染色。该肽进一步用（18）F 标记进行正电子发射断层扫描成像研究。还进行了（18）F 标记的骨肉瘤特异性肽的细胞摄取和外排以及离体生物分布。
ASGALSPSRLDT 是从生物淘选分离出的主要序列，并命名为 OSP-1。OSP-1 与肝素酶 II/III 家族蛋白具有显著同源性，肝素酶 II/III 家族蛋白与肝素硫酸蛋白聚糖结合并反应。荧光染色显示，FITC-OSP-1-噬菌体或 Cy5.5-OSP-1 与一系列骨肉瘤细胞系具有高结合性，与 UM-SCC1 人头颈部鳞状细胞癌细胞的结合性低，与 293T 细胞几乎没有结合性，而随机肽 OSP-S 几乎与所有细胞系都没有结合性。（18）F-OSP-1 在体外和体内均比（18）F-OSP-S 在 143B 肿瘤细胞中的积累明显更高。（18）F-OSP-1 在 143B 肿瘤中的摄取也高于 UM-SCC-1 肿瘤。
我们的数据表明，OSP-1 肽是骨肉瘤特异性的，OSP-1 的结合位点可能与肝素硫酸蛋白聚糖有关。适当标记的 OSP-1 肽有可能成为骨肉瘤成像的新型探针。
