Bardoxolone methyl prevents metabolic dysfunction-associated steatohepatitis by inhibiting macrophage infiltration.

BACKGROUND AND PURPOSE: Bardoxolone methyl (2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid methyl ester, CDDO-Me) is a potent activator of nuclear factor erythroid 2-related factor 2 (Nrf2), which induces the expression of antioxidative-associated genes. CDDO-Me exerts protective effects against chronic inflammatory diseases in the kidneys and lungs. However, its pharmacological effects on metabolic dysfunction-associated steatohepatitis (MASH) caused by fat accumulation remain unknown. In this study, we examined the hepatoprotective effects of CDDO-Me in a diet-induced MASH mouse model and elucidated its pharmacological mechanisms using RNA-seq analysis. EXPERIMENTAL APPROACH: CDDO-Me was orally administered to mice fed a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD), and histological, biochemical, and transcriptomic analyses were performed on livers of mice that developed MASH. KEY RESULTS: CDDO-Me administration induced the expression of antioxidant genes and cholesterol transporters downstream of Nrf2 and significantly prevented the symptoms of MASH. Whole-transcriptome analysis revealed that CDDO-Me inhibited the inflammatory pathway that led to phagocyte recruitment, in addition to activating the Nrf2-dependent pathway. Among inflammatory pathways, CC chemokine ligands (CCL)3 and CCL4, which are downstream of NF-κB and are associated with the recruitment of macrophages expressing CC chemokine receptors (CCR)1 and CCR5, were released into the blood in MASH mice. However, CDDO-Me directly inhibited the expression of CCL3-CCR1 and CCL4-CCR5 in macrophages. CONCLUSIONS AND IMPLICATIONS: Overall, we revealed the potent hepatoprotective effect of CDDO-Me in a MASH mouse model and demonstrated that its pharmacological effects were closely associated with a reduction of macrophage infiltration, through CCL3-CCR1 and CCL4-CCR5 inhibition, in addition to Nrf2-mediated hepatoprotective effects.

Sorting nexin 2-mediated membrane trafficking of c-Met contributes to sensitivity of molecular-targeted drugs.

The sorting nexin (SNX) family is a diverse group of cytoplasmic and membrane-associated proteins that are involved in membrane-trafficking steps within the endocytotic network. SNX1 and SNX2 are components of the mammalian retromer complex and they also play critical roles in the membrane trafficking of growth factor receptors including epidermal growth factor receptor (EGFR) and c-Met. The human lung cancer cell lines, which harbor activating mutations in the kinase domain of EGFR gene, are sensitive to EGFR-targeted drugs gefitinib or erlotinib. However, a lung cancer cell line harboring gene amplification of c-Met is sensitive to the c-Met-targeted drug SU11274 but not to EGFR-targeted drugs. C-Met overexpression is identified as one of the bypass mechanisms for acquired resistance to EGFR-targeted drugs. Here we show that the siRNA-mediated knockdown of SNX2 decreases the cell-surface localization of c-Met, but not that of EGFR, resulting in lysosomal degradation of the c-Met protein. SNX2 specifically interacts with c-Met and treatment with lysosomal inhibitors almost completely annihilates downregulation of c-Met protein by SNX2 knockdown. Therefore, silencing of SNX2 markedly alters sensitivity to anticancer drugs targeted to c-Met (SU11274) and EGFR (gefitinib and erlotinib) through promotion of compensatory activation of the EGFR pathway in lung cancer cells. These findings suggest that development of drugs targeting SNX2 could be useful in overcoming drug resistance to EGFR-targeted drugs in lung cancer cells harboring c-Met gene amplification.

Novel Keap1-Nrf2 Protein-Protein Interaction Inhibitor UBE-1099 Ameliorates Progressive Phenotype in Alport Syndrome Mouse Model.

Background: Bardoxolone methyl activates nuclear factor erythroid 2-related factor 2 (Nrf2) via covalent binding and irreversible inhibition of Kelch-like ECH-associated protein 1 (Keap1), the negative regulator of Nrf2. Ongoing clinical trials of bardoxolone methyl show promising effects for patients with CKD. However, the direct inhibition of Keap1-Nrf2 protein-protein interaction (PPI) as an approach to activate Nrf2 is less explored. Methods: We developed a noncovalent Nrf2 activator UBE-1099, which highly selectively inhibits Keap1-Nrf2 PPI, and evaluated its efficacy on the progressive phenotype in an Alport syndrome mouse model (Col4a5-G5X). Results: Similar to bardoxolone methyl, UBE-1099 transiently increased proteinuria and reduced plasma creatinine in Alport mice. Importantly, UBE-1099 improved the glomerulosclerosis, renal inflammation, and fibrosis, and prolonged the life span of Alport mice. UBE-1099 ameliorated the dysfunction of Nrf2 signaling in the renal tissue of Alport mice. Moreover, transcriptome analysis in the glomerulus showed that UBE-1099 induced the expression of genes associated with the cell cycle and cytoskeleton, which may explain its unique mechanism of improvement such as glomerular morphologic change. Conclusions: UBE-1099 significantly ameliorates the progressive phenotype in Alport mice. Our results revealed the efficacy of Keap1-Nrf2 PPI inhibitor for glomerulosclerosis and present a potential therapeutic drug for CKD.