Central Office for Clinical Pharmacy Training, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima 770-8503, Japan.
J Immunol. 2013 Jun 15;190(12):6239-49. doi: 10.4049/jimmunol.1300448. Epub 2013 May 20.
Podoplanin (Aggrus), which is a type I transmembrane sialomucin-like glycoprotein, is highly expressed in malignant pleural mesothelioma (MPM). We previously reported the generation of a rat anti-human podoplanin Ab, NZ-1, which inhibited podoplanin-induced platelet aggregation and hematogenous metastasis. In this study, we examined the antitumor effector functions of NZ-1 and NZ-8, a novel rat-human chimeric Ab generated from NZ-1 including Ab-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity against MPM in vitro and in vivo. Immunostaining with NZ-1 showed the expression of podoplanin in 73% (11 out of 15) of MPM cell lines and 92% (33 out of 36) of malignant mesothelioma tissues. NZ-1 could induce potent ADCC against podoplanin-positive MPM cells mediated by rat NK (CD161a(+)) cells, but not murine splenocytes or human mononuclear cells. Treatment with NZ-1 significantly reduced the growth of s.c. established tumors of MPM cells (ACC-MESO-4 or podoplanin-transfected MSTO-211H) in SCID mice, only when NZ-1 was administered with rat NK cells. In in vivo imaging, NZ-1 efficiently accumulated to xenograft of MPM, and its accumulation continued for 3 wk after systemic administration. Furthermore, NZ-8 preferentially recognized podoplanin expressing in MPM, but not in normal tissues. NZ-8 could induce higher ADCC mediated by human NK cells and complement-dependent cytotoxicity as compared with NZ-1. Treatment with NZ-8 and human NK cells significantly inhibited the growth of MPM cells in vivo. These results strongly suggest that targeting therapy to podoplanin with therapeutic Abs (i.e., NZ-8) derived from NZ-1 might be useful as a novel immunotherapy against MPM.
足突蛋白（Aggrus）是一种 I 型跨膜唾液酸糖蛋白样糖蛋白，在恶性胸膜间皮瘤（MPM）中高度表达。我们之前报道了一种抗人足突蛋白 Ab，即 NZ-1 的产生，该 Ab 可抑制足突蛋白诱导的血小板聚集和血源性转移。在这项研究中，我们检查了 NZ-1 和 NZ-8 的抗肿瘤效应功能，NZ-8 是一种新型的大鼠-人嵌合 Ab，由 NZ-1 产生，包括体外和体内针对 MPM 的抗体依赖性细胞毒性（ADCC）和补体依赖性细胞毒性。用 NZ-1 进行免疫染色显示，在 73%（15 个中的 11 个）的 MPM 细胞系和 92%（36 个中的 33 个）的恶性间皮瘤组织中表达足突蛋白。NZ-1 可诱导针对足突蛋白阳性 MPM 细胞的强大 ADCC，由大鼠 NK（CD161a(+））细胞介导，但不能由鼠脾细胞或人单核细胞介导。在 SCID 小鼠中，用 NZ-1 治疗可显著减少皮下建立的 MPM 细胞（ACC-MESO-4 或转染足突蛋白的 MSTO-211H）肿瘤的生长，只有当 NZ-1 与大鼠 NK 细胞一起使用时才会发生这种情况。在体内成像中，NZ-1 可有效地积聚到 MPM 的异种移植物中，并且在全身给药后 3 周内仍继续积聚。此外，与正常组织相比，NZ-8 优先识别 MPM 中表达的足突蛋白。与 NZ-1 相比，NZ-8 可诱导更高的由人 NK 细胞介导的 ADCC 和补体依赖性细胞毒性。用 NZ-8 和人 NK 细胞治疗可显著抑制体内 MPM 细胞的生长。这些结果强烈表明，用 NZ-1 衍生的治疗性 Ab（即 NZ-8）靶向足突蛋白可能是一种针对 MPM 的新型免疫疗法。
