Anthocyanins in the black soybean (Glycine max L.) protect U2OS cells from apoptosis by inducing autophagy via the activation of adenosyl monophosphate-dependent protein kinase

Abstract

Abstract. Anthocyanins (ATCs) have been reported to induce apoptosis in various types of cancer cells, stimulating the development of ATCs as a cancer chemotherapeutic or chemopreventive agent. It was recently reported that ATCs can induce autophagy, however, the mechanism for this remains unclear. In the present report, we carried out mechanistic studies of the mechanism involved in ATC-induced autophagy using ATCs extracted from black soybeans (cv. Cheongja 3, Glycine max L.). ATCs clearly induced hallmarks of autophagy, including LC3 puncta formation and the conversion of LC3-I to LC3-II in U2OS human osteosarcoma cells. The induction of autophagy was accompanied by the phosphorylation of multiple protein kinases including extracellular signal-regulated kinase (ERK)1/2, p38 mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK), protein kinase B (AKT) and adenosyl mono phosphate-dependent protein kinase (AMPK). While chemical inhibitors against ERK1/2, p38 MAPK, JNK and AKT failed to inhibit ATC-induced autophagy, the suppression of AMPK by compound C (CC) as well as siRNA against AMPK reduced ATC-induced autophagy. The treatment of ATCs resulted in a decrease in intracellular ATP contents and the activation of AMPK by AICAR treatment also induced autophagy. It is noteworthy that the reduction of autophagy via the inhibition of AMPK resulted in enhanced apoptosis in ATC-treated cells. In addition, siRNA against forkhead box O3A (FOXO3a), a downstream target of AMPK, suppressed ATC-induced autophagy and p27 KIP1 siRNA increased apoptosis in ATC-treated cells. Collectively, it can be concluded that ATCs induce autophagy in U2OS cells via activation of the AMPK-FOXO3a pathway and protect cells from ATC-induced apoptosis via the AMPK-p27 KIP1 pathway. These results also suggest that autophagy-modulating agents could contribute to the efficient development of ATCs as anticancer therapy.

Dendropanoxide Induces Autophagy through ERK1/2 Activation in MG-63 Human Osteosarcoma Cells and Autophagy Inhibition Enhances Dendropanoxide-Induced Apoptosis

“…More recent studies have revealed that some natural products, such as anthocyanins, voacamine, riccardin D, paclitaxel and dihydroptychantol A, induce apoptosis and autophagy in human osteosarcoma cells [8]-[12]. In the present study, we have demonstrated for the first time that dendropanoxide (DP), a new compound isolated from Dendropanax morbifera Leveille, also induce autophagy and apoptosis in human osteosarcoma cells.…”

“…Recent studies have demonstrated that autophagy inhibition by its inhibitor can enhance apoptosis in human osteosarcoma cells treated with natural products [8], [11], [12]. To investigate the effect of autophagy on cell apoptosis in DP-treated MG-63 cells, therefore, wortmannin (Wort) and 3-methyladenine (3-MA), two kinds of specific autophagy inhibitors, were used to suppress the autophagy induced by DP treatment.…”

“…Recent studies have revealed that several natural products, including anthocyanins [8], voacamine [9], riccardin D [10], paclitaxel [11] and dihydroptychantol A [12], induce apoptosis and autophagy in human osteosarcoma cells. These studies have demonstrated that they induce autophagy preceding apoptosis and autophagy inhibition by its inhibitor enhances apoptosis in cells treated with them.…”

Sulfasalazine Induces Autophagic Cell Death in Oral Cancer Cells via Akt and ERK Pathways

“…Third, Akt inhibition is associated with increased mitochondrial superoxide and cellular reactive oxygen species (ROS) levels (Degtyarev et al, 2008). Furthermore, Choe et al (2012) and Degtyarev et al (2009) suggested that the inhibition of Akt is associated with the induction of apoptosis and autophagy. Our finding that decreases in phospho-Akt levels are involved in the cell death elicited by SSZ in HSC-4 cells supports these previous findings.…”

The RNA-binding Protein HuD Regulates Autophagosome Formation in Pancreatic β Cells by Promoting Autophagy-related Gene 5 Expression

“…U2OS cells stably expressing GFP-LC3 was established and maintained as described in Ref. 28. The pHuD plasmid was constructed by inserting the mouse coding HuD sequence into the pRFP-C1 plasmid.…”