Department of Pathology, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan.
Oncol Rep. 2011 Dec;26(6):1369-75. doi: 10.3892/or.2011.1449. Epub 2011 Sep 5.
Mesothelioma, a highly aggressive cancer with poor prognosis and refractory to currently available therapies show increasing trends of its incidence in Japan and other developing countries. Although surgery is a gold standard for patients with early mesothelioma, most patients with advanced disease are not suitable for surgical resection and have option of palliative chemotherapy alone. One of the new treatment strategies for mesothelioma, the humanized anti-CD26 monoclonal antibody therapy is under development. CD26, a 110-kDa transmembrane glycoprotein with known dipeptidyl peptidase IV activity, plays a role in tumor development and its expression was reported in various human malignancies. This study determined the preliminary selection criteria for humanized monoclonal anti-CD26 antibody therapy. Eighty-one epithelioid (49 differentiated and 32 less differentiated), 34 sarcomatoid, 19 biphasic mesothelioma and 8 mesothelioma cell lines were immunohistochemically examined using 8 different commercially available anti-CD26 antibodies for membranous and cytoplasmic expression. The cytoplasmic expression of CD26 was observed in all histological types of mesothelioma, while the membranous expression of CD26 was found in 88% of differentiated and 69% of less differentiated epithelioid mesothelioma, and none of sarcomatoid mesothelioma with anti-CD26 antibodies with rabbit polyclonal anti-DPP4 antibody and similar results were also obtained with goat polyclonal anti-DPP4/CD26 antibody. These antibodies absorbed with soluble human CD26 proteins do not show CD26 expression in mesothelioma tissue, suggesting these two antibodies localize true CD26 protein. Seven mesothelioma cell lines, including sarcomatoid types, also showed membranous expression of CD26 in cellblock preparation. CD26 vector transfection to CD26-negative MSTO-211H cells showed membranous expression of CD26 by flow cytometry, but not in tumor developed in NOD/SCID mice with inoculation of CD26 vector transfected MSTO-211H cells. We found that both rabbit and goat polyclonal antibodies are suitable for immunohistochemical evaluation of membranous expression of CD26 in mesothelioma.
间皮瘤是一种侵袭性强、预后差且对现有治疗方法具有抗药性的癌症，其发病率在日本和其他发展中国家呈上升趋势。虽然手术是早期间皮瘤患者的金标准，但大多数晚期疾病患者不适合手术切除，只能选择姑息性化疗。间皮瘤的一种新治疗策略是开发人源化抗 CD26 单克隆抗体治疗。CD26 是一种 110kDa 的跨膜糖蛋白，具有已知的二肽基肽酶 IV 活性，在肿瘤发展中发挥作用，其表达已在各种人类恶性肿瘤中报道。本研究确定了人源化单克隆抗 CD26 抗体治疗的初步选择标准。使用 8 种不同的商业抗 CD26 抗体对 81 例上皮样（49 例分化型和 32 例低分化型）、34 例肉瘤样、19 例双相性间皮瘤和 8 种间皮瘤细胞系进行了膜和细胞质表达的免疫组织化学检查。所有组织学类型的间皮瘤均观察到 CD26 的细胞质表达，而 CD26 的膜表达在分化型上皮样间皮瘤的 88%和低分化型上皮样间皮瘤的 69%中发现，而肉瘤样间皮瘤均未见，用兔多克隆抗 DPP4 抗体和类似结果也获得了抗 DPP4/CD26 抗体的兔多克隆抗 DPP4 抗体。用可溶性人 CD26 蛋白吸收这些抗体后，间皮瘤组织中不再显示 CD26 表达，提示这两种抗体定位真正的 CD26 蛋白。包括肉瘤样型在内的 7 种间皮瘤细胞系在细胞块制备中也显示出 CD26 的膜表达。CD26 载体转染 CD26 阴性 MSTO-211H 细胞后，通过流式细胞术显示 CD26 的膜表达，但在接种转染 CD26 载体的 MSTO-211H 细胞的 NOD/SCID 小鼠中未发现肿瘤形成。我们发现兔和山羊多克隆抗体均适用于间皮瘤 CD26 膜表达的免疫组织化学评价。
