Liao Mei-Ying, Kuo Mark Yen-Ping, Lu Tung-Ying, Wang Yi-Ping, Wu Han-Chung
Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, Taipei, Taiwan, R.O.C.
Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan, R.O.C.
Int J Oncol. 2015 Apr;46(4):1788-800. doi: 10.3892/ijo.2015.2876. Epub 2015 Feb 5.
We have generated a novel monoclonal antibody (mAb), OCAb9-1, which specifically binds to various types of cancer cell lines, but not to normal cells. According to the results of immunoaffinity chromatography, LC-MS/MS analysis, co-immunoprecipitation, and RNA interference studies, the target protein of OCAb9-1 is the epithelial cell adhesion molecule (EpCAM). EpCAM is a type I transmembrane glycoprotein which is highly expressed in epithelial-transformed neoplasia and tumor-initiating cells (TICs). However, regulation of EpCAM gene expression in tumors and its role in tumorigenesis are not fully understood. In the present study, we show that EpCAM expression is elevated in several cancer cell lines and tumor tissues. Loss-of-function experiments were performed to demonstrate that EpCAM negatively regulates expression of p53 and p21, and promotes tumor cell growth, colony formation, migration and invasion. The median overall survival of tumor-bearing mice treated with OCAb9-1 was significantly higher than that of PBS-treated mice. Moreover, we report that the interplay between SUZ12 and JMJD3 results in dynamic regulation of lysine 27 trimethylation of histone 3 (H3K27me3). Taken together, our findings suggest that the anti-EpCAM mAb may be suitable for use in cancer diagnosis, prognosis, imaging and therapy. Furthermore, EpCAM overexpression in cancer cells is strongly associated with tumor progression, and may be regulated by epigenetic mechanisms.
我们制备了一种新型单克隆抗体（mAb）OCAb9-1，它能特异性结合多种癌细胞系，但不与正常细胞结合。根据免疫亲和色谱、液相色谱-串联质谱分析、免疫共沉淀和RNA干扰研究结果，OCAb9-1的靶蛋白是上皮细胞粘附分子（EpCAM）。EpCAM是一种I型跨膜糖蛋白，在上皮转化的肿瘤和肿瘤起始细胞（TICs）中高度表达。然而，肿瘤中EpCAM基因表达的调控及其在肿瘤发生中的作用尚未完全明确。在本研究中，我们发现EpCAM在几种癌细胞系和肿瘤组织中表达升高。通过功能缺失实验证明，EpCAM负向调节p53和p21的表达，并促进肿瘤细胞生长、集落形成、迁移和侵袭。用OCAb9-1治疗的荷瘤小鼠的中位总生存期显著高于用磷酸盐缓冲液（PBS）治疗的小鼠。此外，我们报道了SUZ12和JMJD3之间的相互作用导致组蛋白3赖氨酸27三甲基化（H3K27me3）的动态调控。综上所述，我们的研究结果表明，抗EpCAM单克隆抗体可能适用于癌症诊断、预后评估、成像和治疗。此外，癌细胞中EpCAM的过表达与肿瘤进展密切相关，可能受表观遗传机制调控。
