Abstract：
Doxorubicin (DOX) is a highly effective chemotherapeutic agent whose clinical use is hindered by the onset of cardiotoxic effects, resulting in reduced ejection fraction within the first year from treatment initiation. Recently it has been demonstrated that DOX accumulates within mitochondria, leading to disruption of metabolic processes and energetic imbalance. We previously described that phosphoinositide 3-kinase γ (PI3Kγ) contributes to DOX-induced cardiotoxicity, causing autophagy inhibition and accumulation of damaged mitochondria. Here we intend to describe the maladaptive metabolic rewiring occurring in DOX-treated hearts and the contribution of PI3Kγ signalling to this process. Metabolomic analysis of DOX-treated WT hearts revealed an accumulation of TCA cycle metabolites due to a cycle slowdown, with reduced levels of pyruvate, unchanged abundance of lactate and increased Acetyl-CoA production. Moreover, the activity of glycolytic enzymes was upregulated, and fatty acid oxidation downregulated, after DOX, indicative of increased glucose oxidation. In agreement, oxygen consumption was increased in after pyruvate supplementation, with the formation of cytotoxic ROS rather than energy production. These metabolic changes were fully prevented in KD hearts. Interestingly, they failed to increase glucose oxidation in response to DOX even with autophagy inhibition, indicating that PI3Kγ likely controls the fuel preference after DOX through an autophagy-independent mechanism. In vitro experiments showed that inhibition of PI3Kγ inhibits pyruvate dehydrogenase (PDH), the key enzyme of Randle cycle regulating the switch from fatty acids to glucose usage, while decreasing DOX-induced mobilization of GLUT-4-carrying vesicles to the plasma membrane and limiting the ensuing glucose uptake. These results demonstrate that PI3Kγ promotes a maladaptive metabolic rewiring in DOX-treated hearts, through a two-pronged mechanism controlling PDH activation and GLUT-4-mediated glucose uptake.
摘要：
多柔比星（DOX）是一种高效的化疗药物，其临床使用受到心脏毒性作用的阻碍。在治疗开始后的第一年内导致射血分数降低。最近已经证明DOX在线粒体内积累，导致代谢过程中断和能量失衡。我们先前描述了磷酸肌醇3-激酶γ（PI3Kγ）有助于DOX诱导的心脏毒性，引起自噬抑制和受损线粒体的积累。在这里，我们打算描述在DOX治疗的心脏中发生的适应不良的代谢重新布线以及PI3Kγ信号传导对该过程的贡献。对DOX处理的WT心脏的代谢组学分析显示，由于循环减慢，TCA循环代谢产物积累。丙酮酸水平降低，乳酸丰度不变，乙酰辅酶A产量增加。此外，糖酵解酶的活性上调，脂肪酸氧化下调，在DOX之后,表明葡萄糖氧化增加。在协议中,补充丙酮酸后耗氧量增加，形成细胞毒性ROS而不是能量产生。这些代谢变化在KD心脏中被完全阻止。有趣的是,即使抑制自噬，它们也无法增加对DOX的葡萄糖氧化，表明PI3Kγ可能通过自噬非依赖性机制控制DOX后的燃料偏好。体外实验表明，抑制PI3Kγ抑制丙酮酸脱氢酶（PDH），Randle循环的关键酶调节从脂肪酸到葡萄糖的使用，同时减少DOX诱导的携带GLUT-4的囊泡向质膜的动员并限制随后的葡萄糖摄取。这些结果表明，PI3Kγ促进DOX治疗心脏的适应不良代谢重新布线，通过控制PDH激活和GLUT-4介导的葡萄糖摄取的双管齐下的机制。
