Liquiritin induces apoptosis and autophagy in cisplatin (DDP)-resistant gastric cancer cells in vitro and xenograft nude mice in vivo

Gastric cancer is reported as one of the leading factors resulting in tumor-related death worldwide. However, the therapies to suppress gastric cancer are still limited and the emergence of drug resistance makes it necessary to develop new and effective anticancer drugs and combinational chemotherapy schemes. Liquiritin (LIQ) is a major constituent of Glycyrrhiza Radix, exhibiting various pharmacological activities, including anticancer. In this study, we investigated the role of LIQ in human gastric cancer cells with cisplatin (DDP) resistance. The findings suggested that LIQ, when applied in single therapy, could moderately inhibit the proliferation and migration of DDP-resistant gastric cancer cells, SGC7901/DDP. DDP and LIQ in combination induced G0/G1 cell cycle arrest to suppress the proliferation of gastric cancer cells, which were associated with the decrease of cyclin D1, cyclin A and cyclin-dependent kinase 4 (CDK4) and increase of p53 and p21. In addition, LIQ combined with DDP significantly induce apoptosis and autophagy both in vitro and in vivo through enhancing cleavage of caspase-8/-9/-3 and PARP, as well as LC3B and Beclin 1 expression. Significantly, the two drugs, when used in combination, prevented gastric cancer cell xenografts in nude mice in vivo. Together, the results revealed that application of DDP and LIQ in combination possessed a potential value against the growth of human gastric cancer with DDP resistance.