'Circulating' RNA-based therapies in Cardio-Oncology

CircMLH3 induces mononuclear macrophage pyroptosis in sepsis by sponging miR-590-3p to regulate TAK1 expression

Sepsis is a fatal syndrome characterized by uncontrolled systemic inflammatory responses. Circular RNAs (circRNAs) are involved in the modulation of various pathophysiological processes, but their potential role in sepsis has largely been unexplored. In this study, we observed differential expression of circMLH3 between healthy volunteers and septic patients, and revealed the value of circMLH3 for sepsis diagnosis and prognostic prediction. Interestingly, we discovered a correlation between the expression level of circMLH3 and the degree of pyroptosis, a critical mechanism contributing to uncontrolled inflammation in sepsis patients. Knocking down circMLH3 alleviated macrophage pyroptosis whereas overexpressing circMLH3 aggravated pyroptosis. circMLH3 regulated macrophage pyroptosis by sponging miR-590-3p and subsequently modulating TAK1 expression. Furthermore, we found that the miR-590-3p/TAK1 axis inhibited the activation of pro-caspase-1 and the NLRP3 inflammasome. miR-590-3p overexpression had a protective effect by reducing macrophage pyroptosis, thereby alleviating sepsis-induced lung injury and systemic inflammatory responses. In conclusion, our study elucidated the circMLH3/miR-590-3p/TAK1 signaling pathway and identified its role in regulating mononuclear macrophage pyroptosis, thus providing potential novel targets and strategies for sepsis diagnosis and therapy.

Chemotherapy-Induced Senescence Reprogramming Promotes Nasopharyngeal Carcinoma Metastasis by circRNA-Mediated PKR Activation

Senescence is associated with tumor metastasis and chemotherapy resistance, yet the mechanisms remain elusive. Here, it is identified that nasopharyngeal carcinoma (NPC) patients who developed distant metastasis are characterized by senescence phenotypes, in which circWDR37 is a key regulator. CircWDR37 deficiency limits cisplatin or gemcitabine-induced senescent NPC cells from proliferation, migration, and invasion. Mechanistically, circWDR37 binds to and dimerizes double-stranded RNA-activated protein kinase R (PKR) to initiate PKR autophosphorylation and activation. Independent of its kinase activity, phosphorylated PKR induces I-kappaB kinase beta (IKKβ) phosphorylation, binds to and releases RELA from NF-κB inhibitor alpha (IκBα) to trigger nuclear factor kappa B (NF-κB) activation, thereby stimulating cyclin D1 (CCND1) and senescence-associated secretory phenotype component gene transcription in a circWDR37-dependent manner. Low circWDR37 levels correlate with chemotherapy response and favorable survival in NPC patients treated with gemcitabine or cisplatin induction chemotherapy. This study uncovers a new mechanism of circWDR37 activated PKR in senescence-driven metastasis and provides appealing therapeutic targets in NPC.