Purpose: This study aimed at investigating the anti-tumor effect of arsenic sulfide (As2S2) against liver cancer both in vivo and in vitro and to elucidate its underlying mechanisms.
Methods: Cell viability of the human hepatocellular carcinoma cell lines SMMC-7721, BEL-7402, HepG2 were measured by CCK-8 assay. The effects of As2S2 on cell proliferation and apoptosis of SMMC-7721 cells were investigated using Calcein-AM and PI staining, Hoechst 33258 staining, crystal violet staining, and JC-1 staining. Cell cycle and Annexin V/PI assay were analyzed via flow cytometry. The expression of apoptosis-related proteins, phosphorylation of PI3K and AKT were detected by Western blotting. H22-bearing mice model was established to evaluate the anti-tumor effect of As2S2 in vivo. HE staining, PCNA was observed via immunohistochemistry, and TUNEL assay was used to assess the anti-proliferation and pro-apoptotic effects of As2S2.
Results: As2S2 significantly inhibited the growth of human hepatoma cells SMMC-7721, BEL-7402 and HepG2. As2S2 inhibited cell proliferation effectively by inducing G0/G1 cell cycle arrest in SMMC-7721 cells. As2S2 could increase Bax/Bcl-2 ratio, decrease mitochondrial membrane potential, promote the release of cytochrome c, increase the levels of cleaved caspase-3 and PARP, indicating that As2S2 induced apoptosis in SMMC-7721 cells via mitochondrial-mediated apoptosis pathway. Further research showed that As2S2 inhibited the PI3K/AKT signaling pathway leading to apoptotic cell death. In addition, As2S2 significantly inhibited tumor growth in H22-bearing mice and induced apoptosis by deactivating PI3K/AKT pathway, which was consistent with the in vitro results.
Conclusion: These findings suggested that As2S2 could induce apoptosis of liver cancer cells in vitro and in vivo, which was related to PI3K/AKT-mediated mitochondrial pathway and may provide a novel promising therapeutic agent for liver cancer treatment.
Keywords: Apoptosis; As2S2; Liver cancer; PI3K/AKT pathway; SMMC-7721 cells.