ABSTRACT
Objective: To investigate the therapeutic effect and mechanism of lenvatinib on regorafenib-resistant hepatocellular carcinoma cells. Methods: CCK-8 and clone formation assay were used to observe the inhibitory effect of lenvatinib on the growth of hepatocellular carcinoma cells. Flow cytometry was used to detect the apoptosis of regorafenib-resistant hepatocellular carcinoma cells treated with lenvatinib. The expression levels of related proteins were detected by western blot and immunohistochemical staining. The inhibitory effect of lenvatinib on the tumor formation ability of regorafenib-resistant hepatocellular carcinoma cells in vivo was observed by subcutaneous tumor formation experiment in mice. Results: CCK-8 and clone formation assay showed that lenvatinib could inhibit the proliferation of regorafenib-resistant hepatocellular carcinoma cells. The number of clones of HepG2, SMMC7721 and regorafenib-resistant HepG2, SMMC7721 cells in lenvatinib group (120.67±11.06, 53.00±11.14, 55.00±9.54, 78.67±14.64) were all lower than those in control group (478.00±24.52, 566.00±27.87, 333.67±7.02, 210.00±12.77, all P<0.05). Flow cytometry showed that lenvatinib could promote apoptosis of regorafenib-resistant hepatocellular carcinoma cells, the apoptosis rates of HepG2, SMMC7721 and regorafenib-resistant HepG2, SMMC7721 cells in lenvatinib group [(12.30±0.70)%, (9.83±0.38)%, (15.90±1.32)%, (10.60±0.00)%] were all higher than those in control group [(7.50±0.87)%, (5.00±1.21)%, (8.10±1.61)%, (7.05±0.78)%, all P<0.05]. The apoptosis-related protein levels suggested that apoptosis was increased in the treatment of lenvatinib. The animal study showed that lenvatinib can inhibit the growth of regorafenib-resistant cells in vivo. Immunohistochemistry and western blot results showed that lenvatinib could down-regulate the abnormally activated IGF1R/Mek/Erk signaling pathway in regorafenib-resistant cells. Conclusion: Lenvatinib can reverse regorafenib resistance in hepatocellular carcinoma, possibly by down-regulating IGF1R/Mek/Erk signaling pathway.