The therapeutic strategy is determined by protein expression using immunohistochemistry of estrogen receptor (ER), progesterone receptor, and human epidermal growth factor receptor 2 (HER2) in formalin-fixed paraffin-embedded (FFPE) breast cancer tissues. However, few proteins function independently, and many of them functions due to protein-protein interactions (PPIs) with other proteins. Therefore, it is important to focus on PPIs. This review summarizes the PPIs of ER and HER2 in breast cancer, especially those using a proximity ligation assay that can visualize PPIs in FFPE tissues. In particular, assessing the interaction of CEACAM6 with HER2 may serve as a surrogate marker for the efficacy of trastuzumab in patients with breast cancer. Therefore, in this review, the technique used to detect the interaction of CEACAM6 and HER2 in routinely processed pathological specimens will be applied to the clinical practice of drug selection. We showed the possibility as a novel pathological examination method using PPIs.

治疗策略是通过使用福尔马林固定石蜡包埋 (FFPE) 乳腺癌组织中雌激素受体 (ER)、孕酮受体和人表皮生长因子受体 2 (HER2) 的免疫组织化学的蛋白质表达来确定的。然而，很少有蛋白质独立发挥作用，其中许多是由于与其他蛋白质的蛋白质-蛋白质相互作用 (PPI) 而起作用。因此，重点关注 PPI 很重要。这篇综述总结了乳腺癌中 ER 和 HER2 的 PPI，尤其是那些使用邻近结扎试验可以可视化 FFPE 组织中 PPI 的那些。特别是，评估 CEACAM6 与 HER2 的相互作用可作为曲妥珠单抗在乳腺癌患者中疗效的替代标志物。因此，在本次审查中，用于检测常规处理的病理标本中CEACAM6和HER2相互作用的技术将应用于药物选择的临床实践。我们展示了使用 PPI 作为一种新的病理检查方法的可能性。