Oxidative-Stress-Mediated ER Stress Is Involved in Regulating Manoalide-Induced Antiproliferation in Oral Cancer Cells

Abstract

Manoalide provides preferential antiproliferation of oral cancer but is non-cytotoxic to normal cells by modulating reactive oxygen species (ROS) and apoptosis. Although ROS interplays with endoplasmic reticulum (ER) stress and apoptosis, the influence of ER stress on manoalide-triggered apoptosis has not been reported. The role of ER stress in manoalide-induced preferential antiproliferation and apoptosis was assessed in this study. Manoalide induces a higher ER expansion and aggresome accumulation of oral cancer than normal cells. Generally, manoalide differentially influences higher mRNA and protein expressions of ER-stress-associated genes (PERK, IRE1α, ATF6, and BIP) in oral cancer cells than in normal cells. Subsequently, the contribution of ER stress on manoalide-treated oral cancer cells was further examined. ER stress inducer, thapsigargin, enhances the manoalide-induced antiproliferation, caspase 3/7 activation, and autophagy of oral cancer cells rather than normal cells. Moreover, N-acetylcysteine, an ROS inhibitor, reverses the responses of ER stress, aggresome formation, and the antiproliferation of oral cancer cells. Consequently, the preferential ER stress of manoalide-treated oral cancer cells is crucial for its antiproliferative effect.

Shikonin Induces ROS-Dependent Apoptosis Via Mitochondria Depolarization and ER Stress in Adult T Cell Leukemia/Lymphoma

“…The ER and mitochondria play crucial roles in regulating cellular homeostasis and cell death, especially cross-talk of these organelles mediated by Calcium ion are important for survival of cancer cells [ 34 ]. The link between induction of ROS, activation of the ER stress pathway, and apoptotic death has been demonstrated in various cancer cell lines by various natural compounds [ 35 , 36 , 37 , 38 ]. We showed here that SHK rapidly induced apoptosis of ATLL cells by activating both the extrinsic or death receptor pathway and the intrinsic or mitochondrial pathway ( Figure 2 ).…”

Physapruin A Exerts Endoplasmic Reticulum Stress to Trigger Breast Cancer Cell Apoptosis via Oxidative Stress

“…The seeding density was 1.5 × 10 5 (MCF7) or 2 × 10 5 (MDA-MB-231) cells/well in a 6-well plate. After overnight culture, cells were treated with various concentrations of PHA for 24 h. After harvested by 0.05% Trypsin-EDTA (Gibco, Grand Island, NY, USA), organelle-ID RGB ® III dye (Enzo Life Sciences, Farmingdale, NY, USA) [54,55] was used to detect ER contents, which is proportional to the degree of ER stress. When cells are under ER stress, ER contents are increased, called ER expansion.…”

“…The seeding density and culture condition are the same as in Section 4.3. Proteostat ® Aggresome Detection kit (Enzo Life Sciences) [55,56] was used to detect aggresome levels proportional to the degree of ER stress. Following 4% paraformaldehyde fixation for 30 min, cells were treated with 0.5% Triton X-100 (30 min, 4 • C).…”

“…After overnight culture, cells were treated with PHA (10 µM) for 24 h. RNA and cDNA conversion were prepared, and a touch-down program was run for quantitative RT-PCR (qRT-PCR) as described [57]. ER stress-responsive genes such as IRE1α, ATF6, PERK, and BIP [58] and internal control GAPDH were selected, and their primer information has been reported [55]. The relative mRNA expression was presented as fold activation using the 2 −∆∆Ct method [59].…”

“…After overnight culture, cells were treated with various concentrations of PHA for 24 h. ER stress-responsive protein expressions were conducted by western blotting. Antibodies against ATF6 (Abcam; 1:500), IRE1α, PERK, BIP (Cell signaling, 1:1000), and β-actin (Sigma-Aldrich; 1:5000) were applied as described [55].…”