2-Hydroxypropyl-β-cyclodextrin blocks autophagy flux and triggers caspase-8-mediated apoptotic cascades in HepG2 cells

The cyclodextrin derivative, 2-Hydroxypropyl-β-cyclodextrin (HPβCD), from the cyclodextrin family is widely used as a drug carrier and offers promising strategies for treating neurodegenerative diseases and atherosclerosis regression. However, its side effects are not fully understood. Therefore, the aim of the present study was to investigate the possible adverse effects of relatively high concentrations of HPβCD on hepatocytes. It was found that a high dose (20 mM) of HPβCD treatment significantly inhibited the AKT/mTOR pathway and disrupted infusion of autophagosomes and lysosomes, which rapidly led to massive autophagosome accumulation in HepG2 cells. The autophagosomal membrane serves as a platform for caspase-8 oligomerization, which is considered as the key step for its self-activation. Using flow cytometry and TUNEL assay, increased apoptosis of HepG2 cells treated with a high dose HPβCD (20 mM) for 48 h was observed. In addition, western blotting results demonstrated that the expression of cleaved-caspase-8 was positively associated with microtubule-associated protein 1 light chain 3 BII expression, which is an indicator of autophagosome level in the cytoplasm. Therefore, the present study provided novel evidence that HPβCD might be a potential risk contributing to the pathophysiological process of hepatic diseases, especially in an autophagy-deficient state.