Celastrol delays the progression of hepatocellular carcinoma by suppressing SLC1A5-mediated glutamine dependence.

Hepatocellular carcinoma (HCC) is a serious public health problem worldwide due to its high mortality rate and specific therapeutic strategies with rare effective drugs. Glutamine, a critical nutrient for sustaining the cellular vital activities, has become a promising direction for HCC management. Celastrol is a terpenoids natural product isolated from the Tripterygium wilfordii Hook F. and catches attention for its multiple pharmacological activities including anti-HCC therapeutic potential. However, its effects in regulating glutamine metabolism to suppress HCC progression have not been investigated. In this study, Hep3B and HepG2 cells were used to investigate the inhibitory effects of celastrol on hepatoma cells. Subsequently, the biosafety and inhibitory effects of celastrol on tumor growth were investigated in a xenograft animal model of liver cancer. Our results showed that celastrol restrained the proliferation of hepatoma cells which was tightly associated with reduction of glutamine metabolic flux. Mechanistically, celastrol restricted glutamine uptake by inhibiting the SLC1A5 expression to reduce the content of glutamine metabolism intermediates in hepatoma cells thereby interrupting the energy source for cell proliferation. Consistently, similar results were observed in a transplanted HCC tumor mouse model. Interestingly, overexpression of SLC1A5 reversed the efficacy of celastrol in decreasing glutamine metabolic flux to suppress the malignant proliferation of hepatoma cells in vitro and in vivo. Overall, this study provides compelling evidence to demonstrate the efficacy of celastrol in inhibiting hepatocarcinogenesis by suppressing SLC1A5-mediated glutamine dependence, suggesting that celastrol as a natural active compound is expected to be developed as a therapeutic agent for HCC.