LY303511 Enhances TRAIL Sensitivity of SHEP-1 Neuroblastoma Cells via Hydrogen Peroxide–Mediated Mitogen-Activated Protein Kinase Activation and Up-regulation of Death Receptors

Abstract

We recently reported that LY294002 (LY29) and LY303511 (LY30) sensitized tumor cells to drug-induced apoptosis independent of the phosphoinositide 3-kinase/Akt pathway. Here, we investigated the mechanism of LY30-induced sensitization of human neuroblastoma cells to TRAILmediated apoptosis. We provide evidence that LY30-induced increase in intracellular H 2 O 2 up-regulates the expression of TRAIL receptors (DR4 and DR5) in SHEP-1 cells by activating mitogen-activated protein kinases, resulting in a significant amplification of TRAIL-mediated caspase-8 processing and activity, cytosolic translocation of cytochrome c, and cell death. Involvement of the death receptors was further confirmed by the ability of blocking antibodies against DR4 and/or DR5 to inhibit LY30-induced TRAIL sensitization. Pharmacologic inhibition of c-Jun NH 2 terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) activation by SP600125 and PD98059, respectively, blocked LY30-induced increase in sensitization to TRAIL-mediated death. Finally, small interfering RNA-mediated gene silencing of JNK and ERK inhibited LY30-induced increase in surface expression of DR4 and DR5, respectively. These data show that JNK and ERK are two crucial players involved in H 2 O 2 -mediated increase in TRAIL sensitization of tumor cells upon exposure to LY30 and underscore a novel mode of action of this inactive analogue of LY29. Our findings could have implications for the use of LY30 and similar compounds for enhancing the apoptotic sensitivity of neuroblastoma cells that often become refractory to chemotherapy.

γ-Tocotrienol Promotes TRAIL-Induced Apoptosis through Reactive Oxygen Species/Extracellular Signal-Regulated Kinase/p53–Mediated Upregulation of Death Receptors

“…It has already been documented that ROS can activate ERK1/2, which leads to the induction of DR5 and DR4. In addition, LY303511 has been shown to augment TRAIL-induced apoptosis through ERK-mediated upregulation of DR5 and DR4 (39).…”

“…It has been reported that mitogen-activated protein kinases (MAPK), ERK1/2, can regulate the upregulation of DRs by bisindolylmaleimide and LY303511 (38,39). We tested whether γ-T3 mediates its effects through a similar mechanism.…”

Phytochemical Composition of Extracts Prepared from Dietary Cucurbits and their Cytoprotective Efficacies against Hydrogen Peroxide Induced Oxidative Stress in GI Cell-INT407

“…Similarly, high levels of intracellular H 2 O 2 (>1 μM) depletes cellular thioredoxin pool and increases oxidation of glutathione (GSH) and oxidative inactivation of general cellular thiolate-dependent enzymes [33]. Also, H 2 O 2 inhibits thiolate dependent enzymes by oxidation of their active-site thiolate moieties [34]. Similarly, SOD activity was inhibited by H 2 O 2 associated with the reduction of the active site of SOD (Cu 2+ to Cu+), and/or the structural alteration of SOD that restricts access to Cu 2+ [35,36].…”

Azadirone, a Limonoid Tetranortriterpene, Induces Death Receptors and Sensitizes Human Cancer Cells to Tumor Necrosis Factor-related Apoptosis-inducing Ligand (TRAIL) through a p53 Protein-independent Mechanism

“…Because ROS are implicated in the activation of MAPK (38,44) and because azadirone induced ROS, we investigated whether azadirone-induced activation of MAPK is ROS-dependent. Cells were treated with NAC for 1 h before treatment with azadirone for 0.5-8 h. The treatment of cells with NAC abolished azadirone-induced activation of ERK (Fig.…”