Uvangoletin, extracted from Sarcandra glabra, exerts anticancer activity by inducing autophagy and apoptosis and inhibiting invasion and migration on hepatocellular carcinoma cells

Ethnopharmacological relevance: Uvangoletin is a dihydrochalcone extracted from the traditional Chinese medicinal plant Sarcandra glabra. Previous research has showed that uvangoletin could induce leukemia cell death. However, the anticancer effect of uvangoletin on hepatocellular carcinoma (HCC) has not been clarified.

Aim of the study: This study aimed to investigate the anti-cancer effects of uvangoletin on HCC and to explore its underlying mechanisms.

Materials and methods: We measured the anticancer activities of uvangoletin both in vitro and in vivo by MTT assay and HepG2 xenograft model. The effects of uvangoletin on apoptosis, autophagy, migration and invasion were also determined. Apoptosis was evaluated by flow cytometry method. Autophagy was assessed by immunofluorescence assay. Cell migration and invasion ability were validated by wound healing assay and cultrex® 96 well cell migration/invasion assay. The expression level of relevant proteins and pathways were examined by western blot.

Results: The results of MTT assay and HepG2 xenograft model showed that uvangoletin could inhibit HCC cells proliferation in vitro and in vivo. Uvangoletin could induce HepG2 cell apoptosis as evidence by the increased expression of cleaved caspase 3, caspase 8 and Bax while decreased Bcl-2 expression. Wound healing assay and transwell assay showed that uvangoletin inhibited HepG2 cells migration and invasion and reduced vimentin, MMP9, MMP2 expression. Uvangoletin also promoted autophagy in HepG2 cells as confirmed by the accumulation of GFP-LC3 puncta. Autophagy inhibitors like 3-MA or CQ could suppress uvangoletin-induced apoptosis. Importantly, uvangoletin-induced anti-EMT effect was also attenuated after autophagy inhibitors added in. Mechanistically, the expressions of p-JNK, p-ERK, p-p38, p-AKT, p-p70S6k and p-mTOR were significantly decreased after uvangoletin treatment.

Conclusion: Our results showed that uvangoletin could induce apoptotic and autophagic cell death, inhibit cell proliferation and metastasis on HepG2 cells through Akt/mTOR, MAPK and TGFβ/Smad2 signal pathways.