University of Hawai'i Cancer Center, HI, USA.
Clin Cancer Res. 2012 Oct 1;18(19):5352-63. doi: 10.1158/1078-0432.CCR-12-0628. Epub 2012 Aug 14.
Malignant mesothelioma (MM) is an aggressive cancer, resistant to current therapies. Membrane chondroitin sulphate proteoglycan 4 (CSPG4), which has been successfully targeted in melanoma and breast cancer, was found highly expressed in MM, but not in normal mesothelium. Therefore, we explored CSPG4 as a suitable target for monoclonal antibody (mAb)-based immunotherapy for MM.
We assayed adhesion, motility, invasiveness, wound-healing, apoptosis, and anchorage-independent growth of MM cells on cell cultures. CSPG4 expression and signaling was studied by immunoblotting. The growth of MM severe combined immunodeficient (SCID) mice xenografts induced by PPM-Mill cells, engineered to express the luciferase reporter gene, was monitored by imaging, upon treatment with CSPG4 mAb TP41.2. Animal toxicity and survival were assayed in both tumor inhibition and therapeutic experiments.
CSPG4 was expressed on 6 out of 8 MM cell lines and in 25 out of 41 MM biopsies, with minimal expression in surrounding healthy cells. MM cell adhesion was mediated by CSPG4-dependent engagement of ECM. Cell adhesion was inhibited by mAb TP41.2 resulting in decreased phosphorylation of focal adhesion kinase (FAK) and AKT, reduced expression of cyclin D1 and apoptosis. Moreover, mAb TP41.2 significantly reduced MM cell motility, migration, and invasiveness, and inhibited MM growth in soft agar. In vivo, treatment with mAb TP41.2 prevented or inhibited the growth of MM xenografts in SCID mice, with a significant increase in animal survival.
These results establish the safety of CSPG4 mAb-based immunotherapy and suggest that CSPG4 mAb-based immunotherapy may represent a novel approach for the treatment of MM.
恶性间皮瘤（MM）是一种侵袭性癌症，对当前的治疗方法具有抗性。膜型硫酸软骨素蛋白聚糖 4（CSPG4）在黑色素瘤和乳腺癌中已被成功靶向，在 MM 中表达高度，但在正常间皮中不表达。因此，我们探索 CSPG4 作为 MM 基于单克隆抗体（mAb）免疫治疗的合适靶标。
我们在细胞培养物上检测 MM 细胞的黏附、运动、侵袭、伤口愈合、凋亡和锚定非依赖性生长。通过免疫印迹研究 CSPG4 表达和信号转导。通过成像监测由 PPM-Mill 细胞诱导的 MM 严重联合免疫缺陷（SCID）小鼠异种移植的生长，该细胞被工程改造表达荧光素酶报告基因，在接受 CSPG4 mAb TP41.2 治疗后。在肿瘤抑制和治疗实验中，均检测动物毒性和存活率。
在 8 种 MM 细胞系中的 6 种和 41 种 MM 活检中的 25 种表达 CSPG4，在周围健康细胞中表达最小。MM 细胞黏附由 ECM 依赖性 CSPG4 参与介导。mAb TP41.2 抑制细胞黏附，导致粘着斑激酶（FAK）和 AKT 的磷酸化减少、细胞周期蛋白 D1 表达减少和凋亡。此外，mAb TP41.2 显著降低 MM 细胞的运动、迁移和侵袭能力，并抑制 MM 在软琼脂中的生长。在体内，mAb TP41.2 治疗可预防或抑制 MM 异种移植在 SCID 小鼠中的生长，动物存活率显著提高。
这些结果确立了 CSPG4 mAb 为基础的免疫治疗的安全性，并表明 CSPG4 mAb 为基础的免疫治疗可能是治疗 MM 的一种新方法。
