Ooi A, Kobayashi M, Mai M, Nakanishi I
Department of Pathology, Faculty of Medicine, Kanazawa University, Japan.
Lab Invest. 1998 Mar;78(3):345-51.
A total of 396 adenocarcinomas of the stomach were examined immunohistochemically using antibodies specific for the internal domain of human c-erbB-2 protein. Forty of these (consisting of 35 well-differentiated and 5 undifferentiated types) overexpressed c-erbB-2, as evidenced by cytoplasmic membrane staining; these tumors were further examined by fluorescence in situ hybridization using a cosmid probe for 17q11.2-12 (c-erbB-2 locus) on formalin-fixed, paraffin-embedded tissues. This technique enabled us not only to detect c-erbB-2 amplification on a cell-by-cell basis, but also to compare the gene amplification with the protein expression, observe topographical distribution, and establish quantitative pictures of the amplification in vivo condition. In all 40 tumors, we observed gene amplification and found that the cancer cell with the amplification corresponded to the cells overexpressing c-erbB-2. In eight mucosal carcinomas, signals were coalesced to one or two clusters, indicating that the amplified gene resided in a homogeneous staining region (HSR). Among 32 carcinomas invading beyond muscularis mucosae, approximately half were mostly composed of cells with the amplification; the others had populations of tumor cells with and without amplification, which were sometimes in separate zones or areas and sometimes mixed together. In 22 cancers, the amplified genes were exclusively in HSR; however, cancer cells with multiple scattered signals-suggesting that the amplified genes were translocated to other chromosomes-were found exclusively in 6 tumors and concurrently with HSR in 4 tumors. These findings suggest that: (a) the amplification produces c-erbB-2 in the HSR form generally early in the carcinogenesis of gastric adenocarcinomas; and (b) in the process of cancer development, the amplified gene is lost in some cancer cells by uneven segregation of HSR in mitosis, whereas in others, it is kept in HSR or translocated to other chromosomal positions, thereby preserving overexpression of c-erbB-2 protein.
使用针对人c-erbB-2蛋白内部结构域的特异性抗体，对总共396例胃腺癌进行了免疫组织化学检查。其中40例（包括35例高分化型和5例未分化型）c-erbB-2过表达，表现为细胞膜染色；对这些肿瘤在福尔马林固定、石蜡包埋组织上，使用针对17q11.2-12（c-erbB-2基因座）的黏粒探针进行荧光原位杂交进一步检查。该技术不仅使我们能够在逐个细胞的基础上检测c-erbB-2扩增，还能将基因扩增与蛋白表达进行比较，观察其拓扑分布，并建立体内扩增情况的定量图像。在所有40例肿瘤中，我们观察到了基因扩增，并发现具有扩增的癌细胞对应于过表达c-erbB-2的细胞。在8例黏膜癌中，信号聚集成一或两个簇，表明扩增基因位于均匀染色区（HSR）。在32例侵犯超过黏膜肌层的癌中，约一半主要由具有扩增的细胞组成；其他的则有扩增和未扩增的肿瘤细胞群体，它们有时在不同区域或部位，有时混合在一起。在22例癌症中，扩增基因仅存在于HSR中；然而，具有多个散在信号的癌细胞（提示扩增基因易位至其他染色体）仅在6例肿瘤中发现，在4例肿瘤中与HSR同时存在。这些发现提示：（a）扩增通常在胃腺癌发生早期以HSR形式产生c-erbB-2；（b）在癌症发展过程中，扩增基因在有丝分裂时因HSR的不均等分离而在一些癌细胞中丢失，而在其他癌细胞中，它保留在HSR中或易位至其他染色体位置，从而保持c-erbB-2蛋白的过表达。
