片段可结晶伽玛受体（FcγR）介导各种细胞反应，对心血管有显着影响。它们有助于曲妥珠单抗 (TRZ) 的抗癌活性，曲妥珠单抗是一种重组人源化单克隆抗体，可干扰人表皮生长因子受体 2 (HER2)，从而阻断其在心脏细胞中的生理功能。这是导致心脏并发症的原因，阻碍了 TRZ 的临床应用。在这项研究中，我们研究了 FcγR 在 TRZ 心脏毒性中的作用。我们使用 TRZ 的重组抗原结合片段 (Fab) (rFab-HER2) 来检查 Fc 区的缺失是否会导致较少的心肌细胞毒性，同时保留 TRZ 抑制 HER2 的能力。当暴露于 rFab-HER2 时，AC16 成人心室心肌细胞比 TRZ 更不易受到损伤和死亡。具体而言，与rFab-HER2（250μg/mL，相当于~5μM）相比，TRZ在较低浓度（150μg/mL，相当于~1μM）下表现出细胞毒性。与 TRZ 一样，rFab-HER2 负向调节心肌细胞中的 HER2 水平（不会在不表达或表达极低水平 HER2 的 BJ 人成纤维细胞中诱导细胞毒性活性）并抑制下游 ERK/AKT 级联。但rFab-HER2并没有改变心肌细胞线粒体动态平衡，影响细胞凋亡和炎症，但限制了细胞质和线粒体ROS指标。相反，Fc区（50-250μg/mL）对心肌细胞产生直接的细胞毒作用（但对缺乏Fc受体的人成纤维细胞没有作用）。 TRZ (150μg/mL) 显着上调心肌细胞中 FcγRIIA（一种与 TRZ 诱导的抗体依赖性细胞毒性密切相关的 FcγR）的表达水平，而 Fab 片段 (150μg/mL) 则没有影响。我们的结果表明 Fc 区在 TRZ 诱导的心肌细胞毒性中起着重要的致病作用。此外，靶向 FcγRIIA 可能会导致 TRZ 疗法的脱靶效应。© 2024。作者获得中国科学院上海药物研究所和中国药理学会的独家许可。

Fragment crystallizable gamma receptors (FcγRs) mediate various cellular responses with significant cardiovascular implications. They contribute to the anticancer activity of trastuzumab (TRZ), a recombinant humanized monoclonal antibody that interferes with human epidermal growth factor receptor 2 (HER2), thereby blocking its physiological function in cardiac cells. This is responsible for cardiac complications that hamper TRZ clinical application. In this study we investigated the involvement of FcγRs in the TRZ cardiotoxicity. We used a recombinant antigen-binding fragment (Fab) of TRZ (rFab-HER2) to examine whether the absence of the Fc region resulted in fewer cardiomyocyte toxicity while preserving TRZ's ability to inhibit HER2. When exposed to rFab-HER2, AC16 human adult ventricular cardiomyocytes were less vulnerable to damage and death, than to TRZ. Specifically, TRZ exhibited cytotoxicity at a lower concentration (150 µg/mL, corresponding to ~1 µM) compared to rFab-HER2 (250 µg/mL, corresponding to ~5 µM). Like TRZ, rFab-HER2 negatively modulated HER2 levels in cardiomyocyte (without inducing cytotoxic activity in BJ human fibroblast cells that either did not express or express very low levels of HER2) and inhibited the downstream ERK/AKT cascades. But rFab-HER2 did not alter cardiomyocyte mitochondrial dynamic balance, and affect apoptosis and inflammation, while it limited cytosolic and mitochondrial ROS indicators. On contrary, the Fc region (50-250 μg/mL) exerted direct cytotoxic action on cardiomyocytes (but not on human fibroblasts that lacked Fc receptors). TRZ (150 μg/mL) markedly upregulated the expression level of FcγRIIA (a FcγRs strongly involved in TRZ-induced antibody-dependent cellular toxicity) in cardiomyocytes, whereas the Fab fragment (150 μg/mL) had no effect. Our results demonstrate that Fc region plays an important pathogenic role in TRZ-induced cardiomyocyte toxicity. In addition, targeting FcγRIIA might contribute to the off-target effects of TRZ therapy.© 2024. The Author(s), under exclusive licence to Shanghai Institute of Materia Medica, Chinese Academy of Sciences and Chinese Pharmacological Society.