Gambogenic Acid Induces Apoptosis and Protective Autophagy in Human Osteosarcoma Cells

Abstract

Background: The impact of Gambogenic acid (GNA), a bioactive component derived from Gamboge, on osteosarcoma (OS) has not been properly investigated. However, whether GNA could induce autophagy in osteosarcoma cells and its role in inducing autophagy of osteosarcoma remains unclear. Therefore, this study aimed to elucidate apoptosis and autophagy in GNA-treated-143B cells and to explore the association between apoptosis and autophagy in these cells after treatment. Methods: The inhibitory effect of GNA on 143B cells was assessed using Cell Counting Kit-8 (CCK-8) assay. Hoechst staining and flow cytometric analysis were used to examine the apoptosis rate, and Ad-GFP-LC3B transfection was employed to evaluate autophagy in treated cells. Intracellular reactive oxygen species (ROS) level and mitochondrial membrane potential were determined through 2′,7′-Dichlorodihydrofluorescein diacetate (DCFH-DA) and 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetramethylbenzimidazolylcarbocyanine iodide (JC-1) staining, respectively. Additionally, Western blot analysis was utilized to assess the expression of apoptosis-related proteins, autophagy, c-Jun N-terminal kinase (JNK) signaling pathway, and mitochondrial apoptosis pathway. Results: The GNA treatment significantly inhibited 143B cell viability and Colony formation (p < 0.05). We observed the involvement of mitochondrial pathways in GNA-induced cell apoptosis (p < 0.05). Furthermore, GNA treatment induced autophagy, which was suppressed by reactive oxygen species (ROS) scavenger and JNK inhibitor (p < 0.05). Thus, the ROS scavenger hindered JNK phosphorylation (p < 0.05). Inhibition of autophagy by knockdown of AGT5 enhanced both apoptosis rate and cytotoxicity of 143B cells following GNA treatment (p < 0.05). Conclusions: GNA induced apoptosis and autophagy in 143B cells, with apoptosis being associated with the mitochondrial pathway and autophagy being regulated by the ROS-JNK signaling pathway. Additionally, autophagy played a cell-protective role against apoptosis.