■阿霉素(Dox)对不同类型的癌症有效,但它会带来心脏毒性副作用,经常导致不可逆的心力衰竭。然而,围绕这种心脏毒性的复杂性,尤其是在亚致死剂量下,还有待充分阐明。我们调查了响应亚致死性Dox的早期细胞破坏,特别强调磷酸化钙/钙调蛋白依赖性蛋白激酶II(CaMKII)在引发线粒体功能障碍中的作用。
■这项研究利用H9c2心肌细胞模型来鉴定Dox的亚致死浓度,并使用线粒体膜电位(MMP)等标志物研究其对线粒体健康的影响,线粒体自噬启动,和线粒体钙动力学。我们研究了CaMKII的作用和相互作用,动力蛋白相关蛋白1(Drp1),和线粒体钙离子转运蛋白(MCU)在Dox诱导的线粒体破坏中使用特异性抑制剂,例如KN-93、Mdivi-1和Ru360。
■与载体相比,暴露于亚致死剂量的Dox使H9c2细胞中的MMP红绿荧光比降低了40.6%,与媒介物相比,经历线粒体自噬的细胞比例从可忽略的水平增加到62.2%。与媒介物组相比,线粒体钙水平也增加了8.7倍。值得注意的是,CaMKII的激活,特别是它的磷酸化形式,是驱动这些线粒体变化的关键,作为抑制使用KN-93恢复MMP和减少线粒体自噬。然而,抑制Drp1和MCU功能对观察到的线粒体破坏影响有限.
■Dox的亚致死给药通过磷酸化与CaMKII激活密切相关,强调其在早期线粒体破坏中的关键作用。这些发现为开发可以减轻Dox的心脏毒性作用的治疗策略提供了有希望的方向。有可能提高其临床疗效。
UNASSIGNED: Doxorubicin (Dox) is effective against different types of cancers, but it poses cardiotoxic side effects, frequently resulting in irreversible heart failure. However, the complexities surrounding this cardiotoxicity, especially at sublethal dosages, remain to be fully elucidated. We investigated early cellular disruptions in response to sublethal Dox, with a specific emphasis on the role of phosphorylated calcium/calmodulin-dependent protein kinase II (CaMKII) in initiating mitochondrial dysfunction.
UNASSIGNED: This study utilized the H9c2 cardiomyocyte model to identify a sublethal concentration of Dox and investigate its impact on mitochondrial health using markers such as mitochondrial membrane potential (MMP), mitophagy initiation, and mitochondrial calcium dynamics. We examined the roles of and interactions between CaMKII, dynamin-related protein 1 (Drp1), and the mitochondrial calcium uniporter (MCU) in Dox-induced mitochondrial disruption using specific inhibitors, such as KN-93, Mdivi-1, and Ru360, respectively.
UNASSIGNED: Exposure to a sublethal dose of Dox reduced the MMP red-to-green fluorescence ratio in H9c2 cells by 40.6% compared with vehicle, and increased the proportion of cells undergoing mitophagy from negligible levels compared with vehicle to 62.2%. Mitochondrial calcium levels also increased by 8.7-fold compared with the vehicle group. Notably, the activation of CaMKII, particularly its phosphorylated form, was pivotal in driving these mitochondrial changes, as inhibition using KN-93 restored MMP and decreased mitophagy. However, inhibition of Drp1 and MCU functions had a limited impact on the observed mitochondrial disruptions.
UNASSIGNED: Sublethal administration of Dox is closely linked to CaMKII activation through phosphorylation, emphasizing its pivotal role in early mitochondrial disruption. These findings present a promising direction for developing therapeutic strategies that may alleviate the cardiotoxic effects of Dox, potentially increasing its clinical efficacy.