Yamauchi Naoko, Watanabe Akira, Hishinuma Michiyo, Ohashi Ken-Ichi, Midorikawa Yutaka, Morishita Yasuyuki, Niki Toshiro, Shibahara Junji, Mori Masaya, Makuuchi Masatoshi, Hippo Yoshitaka, Kodama Tatsuhiko, Iwanari Hiroko, Aburatani Hiroyuki, Fukayama Masashi
Department of Pathology, Graduate School of Medicine, University of Tokyo, Hongo, Tokyo, Japan.
Mod Pathol. 2005 Dec;18(12):1591-8. doi: 10.1038/modpathol.3800436.
Expression profiling of hepatocellular carcinoma has demonstrated that glypican 3 (GPC3), a heparan sulfate proteoglycan anchored to the membrane, is expressed at a markedly elevated level in hepatocellular carcinoma. In this paper, two monoclonal antibodies against GPC3, GPC3-C02 and A1836A, were confirmed to specifically recognize GPC3 molecule in cells from hepatocellular carcinoma and hepatoblastoma cell lines by immunoblotting, and both were confirmed to recognize different epitopes of the GPC3 molecule by epitope mapping. Then, we evaluated the feasibility of GPC3-immunohistochemistry in the pathological diagnosis of benign and malignant hepatocellular lesions by applying these monoclonal antibodies to formalin-fixed and paraffin-embedded specimens. The immunoreactivity turned out to be identical in the two monoclonal antibodies and was thus confirmed to represent the actual expression of the GPC3 molecule. The expression was observed in the fetal liver, but not in normal adult liver, liver cirrhosis or hepatitis except for a tiny focus of a regenerative nodule of fulminant hepatitis. Diffusely positive staining of GPC3 was observed in malignant hepatocytes in hepatoblastomas and in hepatocellular carcinomas (47/56, 84%). GPC3 expression was independent of the differentiation and size of the hepatocellular carcinoma. On the other hand, there was only weak and focal staining in low-grade (2/8) and high-grade dysplastic nodules (6/8). GPC3 immunoreactivity was detected in only one of 23 metastatic lesions of colorectal carcinoma, and its expression was entirely absent in the liver cell adenoma (0/7), carcinoid tumor (0/1), and cholangiocellular carcinoma (0/16). When compared with immunohistochemistry of hepatocyte antigen and alpha-fetoprotein, GPC3-immunohistochemistry was significantly much more specific and sensitive for hepatocellular carcinomas. Thus, GPC3 was confirmed to be one of the oncofetal proteins now attracting attention for their promise both as markers of hepatocellular carcinoma in routine histological examination and as targets in monoclonal antibody-based hepatocellular carcinoma therapy.
肝细胞癌的表达谱分析表明，硫酸乙酰肝素蛋白聚糖膜联蛋白3（GPC3）在肝细胞癌中表达水平显著升高。本文通过免疫印迹法证实，两种抗GPC3单克隆抗体GPC3-C02和A1836A能特异性识别肝癌和肝母细胞瘤细胞系细胞中的GPC3分子，且通过表位作图证实二者识别GPC3分子的不同表位。然后，我们将这些单克隆抗体应用于福尔马林固定石蜡包埋标本，评估GPC3免疫组化在良恶性肝细胞病变病理诊断中的可行性。结果发现两种单克隆抗体的免疫反应性相同，从而证实其代表GPC3分子的实际表达。在胎儿肝脏中观察到该表达，但在正常成人肝脏、肝硬化或肝炎中未观察到，暴发性肝炎再生结节的微小病灶除外。在肝母细胞瘤和肝细胞癌的恶性肝细胞中观察到GPC3弥漫性阳性染色（47/56，84%）。GPC3表达与肝细胞癌的分化程度和大小无关。另一方面，低级别（2/8）和高级别发育异常结节中仅有微弱的局灶性染色（6/8）。在23例结直肠癌转移灶中仅1例检测到GPC3免疫反应性，在肝细胞腺瘤（0/7）、类癌肿瘤（0/1）和胆管细胞癌（0/16）中完全未检测到其表达。与肝细胞抗原和甲胎蛋白免疫组化相比，GPC3免疫组化对肝细胞癌的特异性和敏感性显著更高。因此，GPC3被证实是一种癌胚蛋白，因其有望作为常规组织学检查中肝细胞癌的标志物以及基于单克隆抗体的肝细胞癌治疗靶点而受到关注。
