Zhang Cheng, Ran Fanlei, Du Lei, Wang Xiaohui, Liu Lei, Liu Jinming, Chen Quan, Cao Yang, Bi Lijun, Hang Haiying
Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Bioengineering (Basel). 2024 Feb 29;11(3):242. doi: 10.3390/bioengineering11030242.
The cellular prion protein (PrPc) is a cell surface glycoprotein that is highly expressed in a variety of cancer tissues in addition to the nervous system, and its elevated expression is correlated to poor prognosis in many cancer patients. Our team previously found that patients with colorectal cancer (CRC) with high-level PrPc expression had significantly poorer survival than those with no or low-level PrPc expression. Mouse antibodies for PrPc inhibited tumor initiation and liver metastasis of PrPc-positive human CRC cells in mouse model experiments. PrPc is a candidate target for CRC therapy. In this study, we newly cloned a mouse anti-PrPc antibody (Clone 6) and humanized it, then affinity-matured this antibody using a CHO cell display with a peptide antigen and full-length PrPc, respectively. We obtained two humanized antibody clones with affinities toward a full-length PrPc of about 10- and 100-fold of that of the original antibody. The two humanized antibodies bound to the PrPc displayed significantly better on the cell surface than Clone 6. Used for Western blotting and immunohistochemistry, the humanized antibody with the highest affinity is superior to the two most frequently used commercial antibodies (8H4 and 3F4). The two new antibodies have the potential to be developed as useful reagents for PrPc detection and even therapeutic antibodies targeting PrPc-positive cancers.
细胞朊蛋白（PrPc）是一种细胞表面糖蛋白，除在神经系统外，还在多种癌症组织中高表达，其表达升高与许多癌症患者的不良预后相关。我们的团队之前发现，PrPc高表达的结直肠癌（CRC）患者的生存率明显低于无PrPc表达或低表达的患者。在小鼠模型实验中，针对PrPc的小鼠抗体可抑制PrPc阳性人CRC细胞的肿瘤起始和肝转移。PrPc是CRC治疗的候选靶点。在本研究中，我们新克隆了一种小鼠抗PrPc抗体（克隆6）并将其人源化，然后分别使用肽抗原和全长PrPc的CHO细胞展示对该抗体进行亲和力成熟。我们获得了两个对全长PrPc亲和力分别约为原始抗体10倍和100倍的人源化抗体克隆。这两种人源化抗体与细胞表面展示的PrPc的结合明显优于克隆6。用于蛋白质印迹和免疫组织化学时，亲和力最高的人源化抗体优于两种最常用的商业抗体（8H4和3F4）。这两种新抗体有潜力被开发为用于PrPc检测的有用试剂，甚至是针对PrPc阳性癌症的治疗性抗体。
