Aspidin PB, a phloroglucinol derivative, induces apoptosis in human hepatocarcinoma HepG2 cells by modulating PI3K/Akt/GSK3β pathway

Aspidin PB, a phloroglucinol derivative isolated from Dryopteris fragrans (L.) Schott, has been previously reported to exert high biological activities. In the present study, we analyzed the apoptotic mechanisms of aspidin PB on human hepatoma cell line, HepG2. Initially, aspidin PB was shown to inhibit the growth of HepG2 cells in a time and dose-dependent manner. After treatment with aspidin PB for 72 h, 48 h and 24 h using MTT assay, the IC50 values were 10.59 μM, 20.86 μM and 46.59 μM, respectively. Aspidin PB was capable to induce apoptosis, as measured by mitochondrial membrane potential (ΔΨm), acridine orange (AO) staining and propidium iodide (PI)/annexin V-FITC double staining. To further explore the signaling pathway of aspidin PB-mediated apoptosis, we examined PI3K/Akt related proteins. Western blot analysis revealed that aspidin PB inhibited PI3K expression, phosphorylation of Ser473 Akt and Ser9 GSK3β followed by up-regulation of nonsteroidal anti-inflammatory drugs activated gene-1 (NAG-1) expression. Similarly, the effects of aspidin PB on PI3K, Akt, GSK3β, NAG-1 expression were abolished by treatment with the PI3K inhibitor, wortmannin. Taken together, our data suggested that the PI3K/Akt/GSK3β signal pathway may represent one of the major mechanisms of the effects of aspidin PB on human hepatocarcinoma cells.

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► Activated Akt phosphorylates GSK3β, which extensively regulates cellular functions.
► NAG-1 is regulated by PI3K/AKT/GSK3β pathway.
► Over-expression of NAG-1 induces caspase-dependent apoptosis.
► Aspidin PB may be promising for clinical application to treat human hepatocarcinoma.