Chemical mimetics of the N-degron pathway alleviate systemic inflammation by activating mitophagy and immunometabolic remodeling.

The Arg/N-degron pathway, which is involved in the degradation of proteins bearing an N-terminal signal peptide, is connected to p62/SQSTM1-mediated autophagy. However, the impact of the molecular link between the N-degron and autophagy pathways is largely unknown in the context of systemic inflammation. Here, we show that chemical mimetics of the N-degron Nt-Arg pathway (p62 ligands) decreased mortality in sepsis and inhibited pathological inflammation by activating mitophagy and immunometabolic remodeling. The p62 ligands alleviated systemic inflammation in a mouse model of lipopolysaccharide (LPS)-induced septic shock and in the cecal ligation and puncture model of sepsis. In macrophages, the p62 ligand attenuated the production of proinflammatory cytokines and chemokines in response to various innate immune stimuli. Mechanistically, the p62 ligand augmented LPS-induced mitophagy and inhibited the production of mitochondrial reactive oxygen species in macrophages. The p62 ligand-mediated anti-inflammatory, antioxidative, and mitophagy-activating effects depended on p62. In parallel, the p62 ligand significantly downregulated the LPS-induced upregulation of aerobic glycolysis and lactate production. Together, our findings demonstrate that p62 ligands play a critical role in the regulation of inflammatory responses by orchestrating mitophagy and immunometabolic remodeling.

Targeting ERRα promotes cytotoxic effects against acute myeloid leukemia through suppressing mitochondrial oxidative phosphorylation.

Acute myeloid leukemia (AML) is an aggressive blood cancer with poor clinical outcomes. Emerging data suggest that mitochondrial oxidative phosphorylation (mtOXPHOS) plays a significant role in AML tumorigenesis, progression, and resistance to chemotherapies. However, how the mtOXPHOS is regulated in AML cells is not well understood. In this study, we investigated the oncogenic functions of ERRα in AML by combining in silico, in vitro, and in vivo analyses and showed ERRα is a key regulator of mtOXPHOS in AML cells. The increased ERRα level was associated with worse clinical outcomes of AML patients. Single cell RNA-Seq analysis of human primary AML cells indicated that ERRα-expressing cancer cells had significantly higher mtOXPHOS enrichment scores. Blockade of ERRα by pharmacologic inhibitor (XCT-790) or gene silencing suppressed mtOXPHOS and increased anti-leukemic effects in vitro and in xenograft mouse models.

Genistein induces apoptosis by down-regulating thioredoxin-1 in human hepatocellular carcinoma SNU-449 cells.

Genistein (GEN), a natural isoflavonoid phytoestrogen, has anti-cancer activity against various types of cancers. However, GEN has not been thoroughly investigated in human hepatocellular carcinoma cells. In this study, we evaluated the anti-cancer effects of GEN on SNU-449 cells. GEN inhibited the proliferation of SNU-449 cells in a concentration-dependent manner. We observed the typical characteristics of apoptosis, such as DNA fragmentation and caspase-3 activation. To identify proteins related to GEN-induced apoptosis, we performed two-dimensional electrophoresis and identified differentially expressed proteins. Proteomic analysis showed that the antioxidant protein thioredoxin-1 was associated with GEN-induced apoptosis. GEN treatment decreased thioredoxin-1 levels and increased intracellular accumulation of reactive oxygen species. In addition, GEN activated apoptosis signal-regulating kinase 1, c-Jun N-terminal kinases (JNK) and p38. We also observed that pretreatment with the JNK and p38 inhibitors (SP600125 and SB203580) decreased GEN-induced cell death. These results indicate that GEN has potential antitumor effects against SNU-449 cells through the down-regulation of thioredoxin-1.