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The anti-tumor antibiotic salinomycin (Sal) was recently identified as a selective inhibitor of breast cancer stem cells; however, the effect of Sal on hepatocellular carcinoma (HCC) is not clear. This study aimed to determine the anti-tumor efficacy and mechanism of Sal on HCC. HCC cell lines (HepG2, SMMC-7721, and BEL-7402) were treated with Sal. Cell doubling time was determinated by drawing growth curve, cell viability was evaluated using the Cell Counting Kit 8. The fraction of CD133+ cell subpopulations was assessed by flow cytometry. We found that Sal inhibits proliferation and decreases PCNA levels as well as the proportion of HCC CD133+cell subpopulations in HCC cells. Cell cycle was analyzed using flow cytometry and showed that Sal caused cell cycle arrest of the various HCC cell lines in different phases. Cell apoptosis was evaluated using flow cytometry and Hoechst 33342 staining. Sal induced apoptosis as characterized by an increase in the Bax/Bcl-2 ratio. Several signaling pathways were selected for further mechanistic analyses using real time-PCR and Western blot assays. Compared to control, β-catenin expression is significantly down-regulated upon Sal addition. The Ca2+ concentration in HCC cells was examined by flow cytometry and higher Ca2+ concentrations were observed in Sal treatment groups. The anti-tumor effect of Sal was further verified in vivo using the hepatoma orthotopic tumor model and the data obtained showed that the size of liver tumors in Sal-treated groups decreased compared to controls. Immunohistochemistry and TUNEL staining also demonstrated that Sal inhibits proliferation and induces apoptosis in vivo. Finally, the role of Sal on in vivo Wnt/β-catenin signaling was evaluated by Western blot and immunohistochemistry. This study demonstrates Sal inhibits proliferation and induces apoptosis of HCC cells in vitro and in vivo and one potential mechanism is inhibition of Wnt/β-catenin signaling via increased intracellular Ca2+ levels.

Objective. Necrostatin-1 (Nec-1) inhibits receptor-interacting protein 1 (RIP1) kinase and programmed necrosis. This study was designed to examine the protective effects and mechanisms of Nec-1 in concanavalin A- (ConA-) induced hepatitis in mice. Methods. C57BL/6 mice were exposed to ConA via tail vein injection and injected intraperitoneally with Nec-1 or vehicle. Levels of serum liver enzymes and histopathology were determined. Levels of inflammatory cytokines with ConA-induced hepatitis were determined with real-time polymerase chain reaction (real-time PCR). The expression of TNF-α, RIP1, and LC3 was detected with immunohistochemical staining. The expression of TNF-α, IFN-γ, IL2, IL6, caspase 3, RIP1, beclin-1, and LC3 protein was assessed by immunofluorescence and western blotting. Autophagosomes were observed with transmission electron microscopy (TEM). Results. Amelioration in liver functions and histopathological changes and the suppression of inflammatory cytokine production were observed in Nec-1-injected mice. Western blotting analysis showed that the expression of TNF-α, IFN-γ, IL2, IL6, and RIP1 was significantly reduced in the Nec-1-injected mice, which was confirmed by immunofluorescence and immunohistochemistry. Autophagosome formation was significantly reduced by Nec-1 treatment, as the expression of beclin-1 and LC3, determined with immunofluorescence and western blotting. Conclusion. These results demonstrate that Nec-1 prevents ConA-induced liver injury via RIP1-related and autophagy-related pathways.