Celastrol triggers CAV-1-mediated mitochondrion cholesterol metabolism and mitophagy to suppress liver cancer

Abstract

Background: Celastrol (CeT), a bioactive natural compound derived from Tripterygium wilfordii Hook. f., exhibits potent anti-cancer properties, partially mediated through modulating lipid metabolism. However, its effects on the intricate lipid landscape of liver cancer and the precise underlying molecular mechanisms remain to be fully elucidated.

Purpose: This study aimed to investigate the mechanism by which CeT induces mitophagy through regulating mitochondrial cholesterol metabolism in liver cancer.

Methods: Filipin staining and enzymatic assays were applied to evaluate CeT-mediated alterations in mitochondrial cholesterol metabolism. RNA sequencing, combined with RT-qPCR, Western blotting, and co-immunoprecipitation, was used to investigate the effect of CeT on the caveolin-1 (CAV-1)/sterol carrier protein-2 (SCP2) axis and its regulatory role in mitochondrial cholesterol metabolism in liver cancer cells. In vivo, xenograft models of liver cancer established in CAV-1 knockout mice were utilized to validate that CeT induces mitophagy via CAV-1 inhibition and subsequent modulation of mitochondrial cholesterol.

Results: CeT triggers significant intracellular cholesterol redistribution, culminating in pronounced cholesterol accumulation within mitochondria. This mitochondrial cholesterol overload activates mitophagy and suppresses liver cancer progression. Mechanistically, CeT disrupts the interaction between CAV-1 and SCP2, thereby impairing intracellular cholesterol trafficking and leading to cholesterol enrichment specifically within mitochondria. This resultant mitochondrial cholesterol accumulation substantially elevates reactive oxygen species (ROS) levels, dissipates mitochondrial membrane potential, and initiates mitophagy, collectively inhibiting liver cancer growth. Notably, CeT effectively attenuated tumor development in both nude mice and CAV-1 knockout mice xenograft models.

Conclusion: Our study demonstrates that CeT reprograms mitochondrial cholesterol homeostasis by inhibiting the CAV-1/SCP2 axis, thereby triggering mitophagy. These findings not only provide a mechanistic foundation for the development of CeT as a promising therapeutic agent against liver cancer but also underscore the potential of targeting organelle-specific cholesterol metabolism as a novel and compelling strategy in oncology.

Keywords: Caveolin-1; Celastrol; Cholesterol metabolism; Liver cancer; Mitophagy.