Gambogic Acid Shows Anti-Proliferative Effects on Non-Small Cell Lung Cancer (NSCLC) Cells by Activating Reactive Oxygen Species (ROS)-Induced Endoplasmic Reticulum (ER) Stress-Mediated Apoptosis

Abstract

Background Gambogic acid (AG) is believed to be a potent anti-cancer agent. ER (endoplasmic reticulum) stress-induced cell apoptosis was identified as one of the anti-proliferative mechanisms of several anti-cancer agents. In this study, we investigated the involvement of ER stress-induced apoptosis in the anti-proliferative effect of GA on NSCLC (non-small cell lung cancer) cells. Material/Methods GA at 0, 0.5, and 1.0 μmol/l was used to treat A549 cells. We also used the ER stress-specific inhibitor 4-PBA (4-phenylbutyric acid) (1 μmol/l) to co-treat the cells incubated with GA. Cell viability was assessed by MTT (methyl thiazolyl tetrazolium) assay. Cell apoptosis was evaluated by MTT (methyl thiazolyl tetrazolium) assay. Intracellular ROS (reactive oxygen species) production was detected by DCFH-DA (2,7- dichloro-dihydrofluorescein diacetate) florescent staining. Western blotting was used to assess the expression and phosphorylation levels of protein. Results GA treatment significantly reduced cell viabilities of NSCLC cells in a concentration-dependent manner. GA treatment increased intracellular ROS level, expression levels of GRP (glucose-regulated protein) 78, CHOP (C/EBP-homologous protein), ATF (activating transcription factor) 6 and caspase 12, as well as the phosphorylation levels of PERK (protein kinase R-like ER kinase) and IRE (inositol-requiring enzyme) 1α. Co-treatment of 4-PBA dramatically impaired the inhibitory effect of GA on cell viability. 4PBA co-treatment also decreased expression levels of GRP78, CHOP, ATF6, and caspase12, as well as the phosphorylation levels of PERK and IRE1α, in GA-treated NSCLC cells, without affecting ROS levels. Conclusions GA inhibited NSCLC cell proliferation by inducing ROS-induced ER stress-medicated apoptosis of NSCLC cells.

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“…It also induces oxidative stress-dependent caspase activation to mediate apoptosis in human bladder cancer T24 and UMUC3 cells [652]. Moreover, GA increases the expressions of ER stress markers such as GRP78, CHOP, activating transcription factor 6 (ATF-6) and caspase-12, and co-treatment with chemical chaperone, 4-PBA, significantly reduces these expressions and apoptosis in human NSCLC A549 cells, so it is suggested that GA induces ER stress to mediate apoptosis [659].…”

Tanshinone I induces cell apoptosis by reactive oxygen species-mediated endoplasmic reticulum stress and by suppressing p53/DRAM-mediated autophagy in human hepatocellular carcinoma

“…In addition, ER stress has been reported to be closely associated with anti-cancer drug-induced cancer cell apoptosis, which is an important downstream target of ROS. Zhu et al reported that apoptosis is induced in non-small cell lung cancer cells via the ROS-mediated ER stress pathway [17]. Moreover, Liu et al demonstrated that shikonin triggers cell apoptosis via the ROS-induced activation of the ER stress pathway [33].…”

“…Many studies have revealed that ROS accumulation in various types of cancers involves cell apoptosis and autophagy induced by anti-tumor drugs [13,14]. Increasing evidence suggests that ROS-mediated ER stress activation is involved in anti-cancer drug-induced apoptosis of cancer cells [15][16][17].…”

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“…Enhanced intracellular ROS level, C/EBP-homologous protein, expression levels of glucose-regulated protein (GRP)78 Activated transcription factor 6 and caspase 12 Activated the inositol-requiring enzyme 1alpha and phosphorylation levels of protein kinase R-like ER kinase (Zhu et al, 2019).…”