Verrucarin A sensitizes TRAIL-induced apoptosis via the upregulation of DR5 in an eIF2α/CHOP-dependent manner

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Verrucarin A sensitizes TRAIL-induced apoptosis via the upregulation of DR5 in an eIF2α/CHOP-dependent manner
D O Moon; Y Asami; H Long; Jae-Hyuk Jang; E Y Bae; Bo Yeon Kim; Y H Choi; C H Kang; Jong Seog Ahn; G Y Kim
Bibliographic Citation
Toxicology in Vitro, vol. 27, no. 1, pp. 257-263
Publication Year
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is one of the most promising candidates for new cancer therapeutics. However, resistance to TRAIL in some cancers remains a current problem in recent. The protein-folding compartment of the endoplasmic reticulum (ER) is particularly sensitive to disturbances, which, if severe, may trigger apoptosis. Therefore, we examined whether verrucarin A (VA) sensitize TRAIL-induced apoptosis in cancer cells by induction of ER stress. We first found that VA induces a major molecule of ER stress, CCAAT/enhancer binding protein homologous protein (CHOP)-dependent DR5 induction and subsequently increases TRAIL-induced cleavage of caspases and PARP in TRAIL-resistant Hep3B cells. Importantly, the transient knockdown using siRNA for CHOP abrogated VA-induced DR5 expression and attenuated TRAIL-induced apoptosis. Treatment with VA also increased the levels of phosphorylation of eukaryotic translation initiation factor-2α (eIF2α), which is a common cellular response of ER stress. Furthermore, salubrinal, a specific eIF2α phosphorylation-inducing agent, increased CHOP and DR5 expression in the presence of VA. In contrast, transfection of mutant-eIF2α significantly reversed VA-induced apoptosis with downregulation of CHOP-dependent DR5 expression. Therefore, VA-induced eIF2α phosphorylation seemed to be important for CHOP and DR5 upregulation and TRAIL-induced apoptosis. In addition, generation of reactive oxygen species (ROS) is an effector molecular in sensitization of VA-induced ER stress. We concluded that VA triggers TRAIL-induced apoptosis by eIF2α/CHOP-dependent DR5 induction via ROS generation.
Verrucarin ATRAILDR5ER stresseIF2aCHOP
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Ochang Branch Institute > Chemical Biology Research Center > 1. Journal Articles
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