Anti-invasion and apoptosis induction of chlorella (Chlorella sorokiniana) in Hep G2 human hepatocellular carcinoma cells

The effects of 80% ethanolic extract derived from commercial granule chlorella (GPE) on cell viability, invasion capacity and apoptosis in human hepatoma cell line (Hep G2 cells) were investigated. The results demonstrated that GPE decreased cell viability, induced apoptosis and showed invasion inhibitory effects in the Hep G2 cells. GPE-triggered apoptosis was confirmed by 4′-6-diamidino-2-phenyindole (DAPI) staining and comet assay. GPE promoted an increase of reactive oxygen species (ROS) and Ca2+, and loss of mitochondrial membrane potential (ΔΨm) accompanied by cytochrome c release that was due to the decrease of Bcl-2 in the Hep G2 cells. GPE also induced the protein levels of apoptosis-inducing factor (AIF), increased the levels of caspase-3, -8 and -9, and stimulated the levels of fatty acid synthase (Fas) and Fas ligand (FasL) in the Hep G2 cells. Additionally GPE inhibited invasion of Hep G2 cells by down-regulation of the expression of matrix metalloproteinase (MMP)-2 and -9. Furthermore, cellular glutathione content and superoxide dismutases (SOD) activities were significantly reduced and thiobarbituric acid-reactive substances (TBARS) levels were significantly increased after GPE treatment. These results suggest that GPE can induce cytotoxicity on Hep G2 cells and inhibit the invasive capacity of malignant cells.

► Chlorella extract induced cytotoxicity on Hep G2 cells.
► The apoptotic mechanism is associated with its pro-oxidant activity in cells.
► We also showed for the first time that it can inhibit the invasion of Hep G2 cells.
► The anti-invasion effect is associated with the decreasing MMP-2 and -9 expressions.