Leung Kam
National Center for Biotechnology Information, NLM, NIH, Bethesda, MD
Patients with pancreatic ductal adenocarcinoma (PDAC) have a median survival of 6 months and a 5-year survival rate of only 3% (1). PDAC is an aggressive cancer with early metastasis in >80% of patients. Early detection would be particularly useful for monitoring people at high risk of developing pancreatic cancer. Plectin-1 was identified in 100% of tested PDAC lesions and 60% of tested preinvasive PanIN III lesions (2). Plectin-1, a cytoskeletal component, is not expressed in the normal pancreas, liver, lymph node, lung, or peritoneum in humans. Using phage display screenings, the linear peptide Lys-Thr-Leu-Leu-Pro-Thr-Pro (KTLLPTP) (Plectin-1–targeting peptide, PTP) (3) has been found to specifically bind to Plectin-1 (4, 5), a protein present both inside and on the membrane of human and mouse PDAC cells but only on the inside of normal pancreatic cells. Kelly et al. (3) conjugated PTP to Cy5.5-labeled cross-linked iron oxide particles (CLIO-Cy5.5) for imaging Plectin-1 expression in PDAC, which suggests that Plectin-1 can serve as a biomarker for PDAC. Bausch et al. (2) labeled a tetrameric PTP with In (4(βAKTLLPTP-GGS(PEG5000))KKK-In-DOTA-βA-NH) (In-tPTP) for single-photon emission computed tomography (SPECT) imaging for primary and metastatic pancreatic tumors.
胰腺导管腺癌（PDAC）患者的中位生存期为6个月，5年生存率仅为3%（1）。PDAC是一种侵袭性癌症，超过80%的患者会早期转移。早期检测对于监测胰腺癌高危人群尤为有用。在100%的检测PDAC病变和60%的检测前浸润性胰腺上皮内瘤变III级病变中发现了网蛋白-1（2）。网蛋白-1是一种细胞骨架成分，在人类正常胰腺、肝脏、淋巴结、肺或腹膜中不表达。通过噬菌体展示筛选，发现线性肽Lys-Thr-Leu-Leu-Pro-Thr-Pro（KTLLPTP）（网蛋白-1靶向肽，PTP）（3）能特异性结合网蛋白-1（4,5），该蛋白存在于人和小鼠PDAC细胞的内部及膜上，但仅存在于正常胰腺细胞内部。凯利等人（3）将PTP与Cy5.5标记的交联氧化铁颗粒（CLIO-Cy5.5）偶联，用于成像PDAC中网蛋白-1的表达，这表明网蛋白-1可作为PDAC的生物标志物。鲍施等人（2）用铟标记四聚体PTP（In(4(βAKTLLPTP-GGS(PEG5000))KKK-In-DOTA-βA-NH)（In-tPTP），用于原发性和转移性胰腺肿瘤的单光子发射计算机断层扫描（SPECT）成像。
