Accumulation of amyloid-β (Aβ), which results in the formation of senile plaques that cause oxidative damage and neuronal cell death, has been accepted as the major pathological mechanism of Alzheimer’s disease (AD). Hence, inhibition of Aβ-induced oxidative damage and neuronal cell apoptosis represents the effective strategies in combating AD. Ginsenoside Re (Re) has pharmacological effects against Aβ-induced neurotoxicity. However, its molecular mechanism remains elusive. The present study evaluated the effect of Re against Aβ-induced cytotoxicity and apoptosis in SH-SY5Y cells, and investigated the underlying mechanism. We demonstrate that Re inhibits the Aβ-triggered mitochondrial apoptotic pathway, as indicated by maintenance of mitochondrial functional, elevated Bcl-2/Bax ratio, reduced cytochrome c release, and inactivation of caspase-3/9. Re attenuated Aβ-evoked reactive oxygen species (ROS) production, apoptosis signal-regulating kinase 1 (ASK1) phosphorylation, and JNK activation. ROS-scavenging abrogated the ability of Re to alter ASK-1 activation. Simultaneously, inhibition of JNK abolished Re-induced Bax downregulation in Aβ-challenged SH-SY5Y cells. In addition, Re enhanced activation of the nuclear factor-E2-related factor 2 (Nrf2) in Aβ-induced SH-SY5Y cells. Knockdown of Nrf2 by small interfering RNA targeting Nrf2 abolished the protective effect of Re. Our findings indicate that Re could be a potential therapeutic approach for the treatment of AD.

20(S)-Ginsenoside Rg3 (GRg3) has various bioactivities including anti-cancer effects and inhibition of autophagy. However, no reports have investigated the appearance of autophagy or the connection between autophagy and apoptosis in HeLa cells treated with 20(S)-GRg3. Cell viability was measured by CCK-8 (cell counting kit-8) assays. Apoptosis and the cell cycle were analyzed by Hoechst 33342 staining and flow cytometry. Apoptotic pathways were examined by ROS (reactive oxygen species) determination and rhodamine 123 assays. Western blot analysis was used to determine changes in protein levels. Autophagy induction was monitored by acidic vesicular organelle staining and EGFP-LC3 transfection. 20(S)-GRg3 inhibited autophagy of cells in a starved state, making it impossible for cells to maintain a steady state through autophagy, and then induced apoptosis. 20(S)-GRg3 blocked the late stage of autophagy (fusion of lysosomes and degradation of autophagic lysosomes), including a decrease in acidic vesicular organelle fluorescence, increased LC3 I–II conversion, accumulation of EGFP-LC3 fluorescence, GFP-mRFP-LC3 red-green fluorescence ratio, degradation of the substrate p62, and loss of the balance between autophagy and apoptosis, which induced apoptosis. ROS increased, the mitochondrial membrane potential decreased, apoptotic inducer AIF was released from mitochondria, and nuclear transfer occurred, triggering a series of subsequent apoptotic events. Autophagy inducer rapamycin inhibited the apoptosis induced by 20(S)-GRg3, whereas autophagy inhibitor BA1 promoted apoptosis induced by 20(S)-GRg3. Therefore, 20(S)-GRg3 promoted HeLa cell apoptosis by regulating autophagy. In the autophagic state, 20(S)-GRg3 can be used as a novel autophagy inhibitor in synergy with tumor-blocking therapies such as chemotherapy, which supports its application in the medical field.

Background: Cancer cells through autophagy-mediated recycling to meet the metabolic demands of growth and proliferation. The steroidal saponin 20(S)-ginsenoside Rh2 effectively inhibits the growth and survival of a variety of tumor cell lines and animal models, but the effects of Rh2 on autophagy remain elusive. Methods: Cell viability was measured by CCK-8 (cell counting kit-8) assays. Apoptosis, ROS generation and mitochondrial membrane potential were analyzed by flow cytometry. Western blot analyses were used to determine changes in protein levels. Morphology of apoptotic cells and autophagosome accumulation were analyzed by DAPI staining and transmission electron microscopy. Autophagy induction was monitored by acidic vesicular organelle staining, EGFP-LC3 and mRFP-GFP-LC3 transfection. Atg7 siRNA and autophagy regulator was used to assess the effect of autophagy on apoptosis induced by G-Rh2. Results: In this study, we found that low concentration G-Rh2 attenuated cancer cell growth and induced apoptosis upon serum-free starvation. Caspase 3 inhibitors failed to block apoptosis in G-Rh2-treated cells, indicating a caspase-independent mechanism. G-Rh2-treated cells in serum-deprived conditions showed impaired mitochondrial function, increased release and nuclear translocation of apoptosis-inducing factor, but little changes in the mitochondrial and cytoplasmic distributions of cytochrome C. Annexin A2 overexpression in 293T cells inhibited G-Rh2-induced apoptosis under serum-starved conditions. Meanwhile, G-Rh2 reduced lysosomal activity and inhibited the fusion of autophagosome and lysosome, leading to a block of autophagic flux. Knockdown Atg7 significantly inhibited autophagy and triggered AIF-induced apoptosis in serm free condition. The autophagy inducer significantly decreased the apoptosis levels of G-Rh2-treated cells in serum-free conditions. Conclusions: Under nutrient deficient conditions, G-Rh2 represses autophagy in cervical cancer cells and enhanced apoptosis through an apoptosis-inducing factor mediated pathway.

20(S)‑Ginsenoside Rh2 [20(S)‑GRh2], one of the main active components of Panax ginseng, induces apoptosis in a wide range of cancer cell types. The present study found that 20(S)‑GRh2 reduces mitochondrial membrane potential, decreases adenosine triphosphate generation and induces reactive oxygen species in HeLa cervical cancer cells. In addition, 20(S)‑GRh2 activated mitochondrion‑dependent apoptosis and inhibited both mitochondrial oxidative phosphorylation and glycolysis in HeLa cells. It was found that voltage‑dependent anion channel 1 (VDAC1) expression was significantly upregulated by 20(S)‑GRh2 treatment, while hexokinase 2 expression was downregulated and segregated from the mitochondria. Furthermore, 20(S)‑GRh2 promoted Bax transport from the cytoplasm to the mitochondria, and knockdown of VDAC1 inhibited Bax transport and apoptosis. These results suggest that VDAC1 is a novel target of 20(S)‑GRh2. The present study provides a better understanding of the mechanistic link between cervical cancer metabolism and growth control, and these results may facilitate the development of new treatments for cervical cancer.