Pseudo-ginsenoside Rh2 induces A549 cells apoptosis via the Ras/Raf/ERK/p53 pathway

Abstract

Ginsenoside Rh2, a major effective constituent of ginseng, has been suggested to have a pro-apoptotic effect in a variety of cancer cells. Pseudo-Ginsenside-Rh2 (pseudo-G-Rh2) is a novel derivative of ginsenoside Rh2. The aim of the present study was to evaluate the effect of pseudo-G-Rh2 on the apoptosis of lung adenocarcinoma A549 cells. The cytotoxicity of pseudo-G-Rh2 on A549 cells was evaluated using an MTT assay. Apoptosis was detected using DAPI staining and flow cytometry. The expression of apoptosis associated proteins was identified by western blot analysis. The results demonstrated that pseudo-G-Rh2 inhibits the proliferation of A549 cells in a dose-dependent manner. DAPI staining revealed topical morphological changes in apoptotic bodies following pseudo-G-Rh2 treatment. Flow cytometric analysis revealed that the percentage of Annexin V-fluorescein isothiocyanate-positive cells, which are apoptotic, increased with pseudo-G-Rh2 treatment in a dose-dependent manner. Furthermore, treatment with pseudo-G-Rh2 increased the level of reactive oxygen species in A549 cells as well as the activation of caspase-9, caspase-3 and poly ADP-ribose polymerase. Pseudo-G-Rh2 treatment was observed to induce mitochondrial membrane potential loss. Furthermore, the results of western blotting revealed that B-cell lymphoma 2 (Bcl-2) expression was significantly decreased while Bcl-2-associated X protein expression was significantly upregulated in A549 cells with pseudo-G-Rh2 treatment. Pseudo-G-Rh2-induced apoptosis was accompanied by sustained phosphorylation of Ras, Raf, extracellular signal-regulated kinase (ERK) and p53. In conclusion, the results of the present study suggest that pseudo-G-Rh2 induces mitochondrial apoptosis in A549 cells and is responsible for excessive activation of the Ras/Raf/ERK/p53 pathway.