The human cancer antigen 125 (CA125) is over-expressed in epithelial ovarian cancer cells and it plays a role in the pathogenesis of ovarian cancer. This protein presents a repeat region containing up to sixty tandem repeat units. The anti-CA125 monoclonal antibodies have been previously classified into three groups: two major families, the OC125-like antibodies and M11-like antibodies, and a third group, the OV197-like antibodies. A model in which a single repeat unit contains all the epitopes for these antibodies has been also proposed, even if their exact position is still undetermined. In the present work, the affinities of the monoclonal antibodies, representative of the three families, have been investigated for different CA125-recombinant repeats through Western blot analysis. Different patterns of antibody recognition for the recombinant repeats show that CA125 epitopes are not uniformly distributed in the tandem repeat region of the protein. The minimal region for the recognition of these antibodies has been also individuated in the SEA domain through the subcloning of deleted sequences of the highly recognized repeat-25 (R-25), their expression as recombinant fragments in E. coli and Western blot analysis. Obtained data have been further confirmed by ELISA using the entire R-25 as coating antigen.

中文翻译：

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OC125、M11 和 OV197 表位在 CA125 的串联重复区域中分布不均匀，需要整个 SEA 域。

人癌抗原 125 (CA125) 在上皮性卵巢癌细胞中过度表达，并在卵巢癌的发病机制中发挥作用。该蛋白质呈现包含多达 60 个串联重复单元的重复区域。抗 CA125 单克隆抗体先前已分为三组：两大家族，OC125 样抗体和 M11 样抗体，以及第三组，OV197 样抗体。还提出了一种模型，其中单个重复单元包含这些抗体的所有表位，即使它们的确切位置仍未确定。在目前的工作中，已经通过蛋白质印迹分析研究了代表三个家族的单克隆抗体对不同 CA125 重组重复的亲和力。重组重复的不同抗体识别模式表明 CA125 表位在蛋白质的串联重复区域中分布不均匀。通过亚克隆高度识别的重复序列 25 (R-25) 的缺失序列，识别这些抗体的最小区域也在 SEA 域中进行了个体化，它们作为重组片段在大肠杆菌和蛋白质印迹分析。使用整个 R-25 作为包被抗原，通过 ELISA 进一步证实了获得的数据。