Induction of Apoptosis by Ethanol Extracts of Ganoderma lucidum in Human Gastric Carcinoma Cells

Inhibition of cell viability by ethanol extracts of G. lucidum (EGL) in AGS cells. The cells were seeded at an initial density of 2.5 × 10⁵ cells per 60 mm plate, incubated for 24 hours, and treated with various concentrations of EGL for the indicated times. The cell viability was measured using 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide or MTT assay. Each point represents the mean ± SD of three independent experiments. Significance was determined using a Student's t test (^*p < 0.05 vs. untreated control).

Induction of apoptosis following treatment of AGS cells with ethanol extracts of G. lucidum (EGL). (A) After incubation with various concentrations of EGL for 72 hours, the cells were sampled and examined using an inverted microscope (magnification, 200×). (B) Cells grown under the same conditions as (A) were sampled, fixed, and stained with 4,6-diamidino-2-phenylindole. The stained nuclei were then observed under a fluorescent microscope using a blue filter (magnification, 400×). (C) AGS cells were treated with various concentrations of EGL for 72 hours or (D) treated with 2% EGL for the indicated times. The cells were collected and stained with fluorescein isothiocyanate-conjugated annexin-V and PI for flow cytometry analysis. The apoptotic cells were determined by counting the percent of annexin V(+)/propidium iodide (−) cells and the percent of annexin V(+)/propidium iodide (+) cells. The results are expressed as the mean ± SD of three independent experiments. The statistical significance of results was analyzed using a Student's t test (^*p < 0.05).

Effects of ethanol extracts of G. lucidum (EGL) treatment on the levels of apoptosis-related proteins in AGS cells. (A) Cells were treated with the indicated concentrations of EGL for 72 hours or (B) treated with 2% EGL for the indicated times. Equal amounts of cell lysates were resolved on sodium dodecyl sulfate polyacrylamide gels and transferred to nitrocellulose membranes. The membranes were probed with the indicated antibodies and proteins were visualized using the enhanced chemiluminescence detection system. Actin was used as an internal control.

Activation of caspases and degradation of poly (ADP ribose) polymerase protein by ethanol extracts of G. lucidum (EGL) treatment in AGS cells. (A) After 72 hours incubation with EGL, the cells were lysed and cellular proteins were separated by sodium dodecyl sulfate polyacrylamide gels and transferred onto nitrocellulose membranes. The membranes were probed with anti-caspase-3, anti-caspase-8, anti-caspase-9 and anti-poly(ADP ribose) polymerase protein antibodies. Proteins were visualized using the enhanced chemiluminescence detection system. Actin was used as an internal control. (B) Cells grown under the same conditions as (A) were collected and lysed. Aliquots were incubated with Asp-Glu-Val-Asp-p-nitroaniline, Ile-Glu-Thr-Asp-p-nitroaniline, and Leu-Glu-His-Asp-p-nitroaniline for caspase-3, −8, and −9, individually, at 37°C for 1 hour. The released fluorescent products were measured. The data represents the mean of three independent experiments. The statistical significance of results was analyzed by a Student's t test (†p< 0.01).

Increase in ethanol extracts of G. lucidum (EGL)-induced cytotoxic effects by the inhibition of the PI3K/ Akt signal pathway in AGS cells. (A) The cells were treated with the indicated concentrations of EGL for 72 hours or treated with 2% EGL for the indicated times. Equal amounts of cell lysates were resolved by sodium dodecyl sulfate polyacrylamide gels, transferred to nitrocellulose, and probed with the anti-Akt and anti-p-Akt antibodies. Proteins were visualized using the enhanced chemiluminescence detection system. (B) AGS cells were treated with LY294002 (10 μM) for 2 hours before being challenged with 2% EGL for 72 hours. The cells were lysed and cellular proteins were separated by sodium dodecyl sulfate polyacrylamide gels and transferred onto nitrocellulose membranes. The membranes were probed with anti-Akt, anti-p-Akt and anti-poly(ADP ribose) polymerase protein antibodies. Proteins were visualized using the enhanced chemiluminescence detection system. Actin was used as an internal control. (C) AGS cells were treated with LY294002 (5 and 10 μM) for 2 hours before being challenged with 2% EGL for 48 or 72 hours. The apoptotic cells were determined by counting the percent of annexin V(+)/propidium iodide (−) cells and the percent of annexin V(+)/propidium iodide (+) cells. The results are expressed as the mean ± SD of three independent experiments. The statistical significance of results was analyzed using Student's t test (^*p < 0.05).