The broad-spectrum antineoplastic drug doxorubicin (DOX) has one of the most serious chronic side effects on the heart, dilated cardiomyopathy, but the precise molecular mechanisms underlying disease progression subsequent to long latency periods remain puzzling. Here, we established a model of DOX-induced dilated cardiomyopathy. In a cardiac cytology exploration, we found that differentially expressed genes in the KEGG signaling pathway enrichment provided a novel complex network of mTOR bridging autophagy and oxidative stress. Validation results showed that DOX caused intracellular reactive oxygen species accumulation in cardiomyocytes, disrupted mitochondria, led to imbalanced intracellular energy metabolism, and triggered cardiomyocyte apoptosis. Apoptosis showed a negative correlation with DOX-regulated cardiomyocyte autophagy. To evaluate whether the inhibition of mTOR could upregulate autophagy to protect cardiomyocytes, we used rapamycin to restore autophagy depressed by DOX. Rapamycin increased cardiomyocyte survival by easing the autophagic flux blocked by DOX. In addition, rapamycin reduced oxidative stress, prevented mitochondrial damage, and restored energy metabolic homeostasis in DOX-treated cardiomyocytes. In vivo, we used metformin (Met) which is an AMPK activator to protect cardiac tissue to alleviate DOX-induced dilated cardiomyopathy. In this study, Met significantly attenuated the oxidative stress response of myocardial tissue caused by DOX and activated cardiomyocyte autophagy to maintain cardiomyocyte energy metabolism and reduce cardiomyocyte apoptosis by downregulating mTOR activity. Overall, our study revealed the role of autophagy and apoptosis in DOX-induced dilated cardiomyopathy and demonstrated the potential role of regulation of the AMPK/mTOR axis in the treatment of DOX-induced dilated cardiomyopathy.

Ethnopharmacological relevance Pulmonary fibrosis (PF) is an irreversible lung disease that severely affects human respiratory function. Traditionally, the natural plant Quzhou Fructus Arantii (QFA) has therapeutic effects on respiratory diseases. However, the effects and the mechanism of anti-fibrotic have not been elucidated. Aim of the study: In this study, QFAE-nB was extracted from QFA, the aims of this study include understanding the correlation between Bleomycin (BLM)-induced PF and STING pathway in mice, as well as exploring the role and mechanisms of QFAE-nB in the treatment of PF. Materials and methods QFAE-nB was extracted from QFA, six main chemical components in QFAE-nB were identified by HPLC–QTOF–MS/MS, and quantitative analysis was conducted by HPLC. qPCR and Western blot were used to verify the molecular mechanism of QFAE-nB, and the anti-fibrotic effect of QFAE-nB was determined by hematoxylin-eosin (HE) staining and Masson staining as well as immunohistochemistry. TREX1-KO and STING-KO mice were used to verify the relationship between STING and PF and the important target action of QFAE-nB. Results: Six main flavonoids in QFAE-nB were identified as eriocitrin (0.76%), neoeriocitrin (2.79%), narirutin (4.31%), naringin (35.41%), hesperidin (1.74%), and neohesperidin (27.18%). The results showed that BLM-induced PF was associated with its exacerbated release of proinflammatory factors and chemokines in lung tissues. In addition, QFAE-nB alleviated BLM-induced lung fibrosis in mice by inhibiting the activation of the STING signaling pathway and reducing the signal transduction of TBK1–IRF3 and TBK1–NF-κB pathways. Notably, knockout of the TREX1 gene caused massive inflammation and even induced PF in the lung tissues, whereas QFAE-nB effectively alleviated inflammation and reduced PF. The deletion of the STING gene suppressed BLM-induced PF and inflammation, but STING-KO mice treated with QFAE-nB showed even lower expression levels of proinflammatory factors and chemokine. Conclusions: The STING pathway plays an important role in PF, and QFAE-nB alleviates PF by mainly targeting the inhibition of the STING pathway to reduce inflammation. Together, the study paves the way for targeting the STING pathway in PF treatment.