This study aimed to investigate the effect and molecular mechanism of sinomenine on proliferation, apoptosis, metastasis, and combination with inhibitors in human hepatocellular carcinoma HepG2 cells and SK-HEP-1 cells. The effect of sinomenine on the growth ability of HepG2 and SK-HEP-1 cells were investigated by CCK-8 assay, colony formation assay, and BeyoClick~(TM) EdU-488 staining. The effect of sinomenine on DNA damage was detected by immunofluorescence assay, and the effect of sinomenine on apoptosis of human hepatocellular carcinoma cells was clarified by Hoechst 33258 staining and CellEvent~(TM) Cystein-3/7Green ReadyProbes~(TM) reagent assay. Cell invasion assay and 3D tumor cell spheroid invasion assay were performed to investigate the effect of sinomenine on the invasion ability of human hepatocellular carcinoma cells in vitro. The effect of sinomenine on the regulation of protein expression related to the protein kinase B(Akt)/mammalian target of rapamycin(mTOR)/signal transducer and activator of transcription 3(STAT3) signaling pathway in HepG2 and SK-HEP-1 cells was examined by Western blot. Molecular docking was used to evaluate the strength of affinity of sinomenine to the target cysteinyl aspartate specific proteinase-3(caspase-3) and STAT3, and combined with CCK-8 assay to detect the changes in cell viability after combination with STAT3 inhibitor JSI-124 in combination with CCK-8 assay. The results showed that sinomenine could significantly reduce the cell viability of human hepatocellular carcinoma cells in a concentration-and time-dependent manner, significantly inhibit the clonogenic ability of human hepatocellular carcinoma cells, and weaken the invasive ability of human hepatocellular carcinoma cells in vitro. In addition, sinomenine could up-regulate the cleaved level of poly ADP-ribose polymerase(PARP), a marker of apoptosis, and down-regulate the protein levels of p-Akt, p-mTOR, and p-STAT3 in human hepatocellular carcinoma cells. Molecular docking results showed that sinomenine had good affinity with the targets caspase-3 and STAT3, and the sensitivity of sinomenine to hepatocellular carcinoma cells was diminished after STAT3 was inhibited. Therefore, sinomenine can inhibit the proliferation and invasion of human hepatocellular carcinoma cells and induce apoptosis, and the mechanism may be attributed to the activation of caspase-3 signaling and inhibition of the Akt/mTOR/STAT3 pathway. This study can provide a new reference for the in-depth research and clinical application of sinomenine and is of great significance to further promote the scientific development and utilization of sinomenine.
Keywords: Akt/mTOR/STAT3 signaling pathway; apoptosis; caspase-3; hepatocellular carcinoma; invasion; molecular docking; sinomenine.