Hydrogen peroxide induces cell death in human TRAIL-resistant melanoma through intracellular superoxide generation

Abstract

Intracellular reactive oxygen species (ROS) such as hydrogen peroxide (H(2)O2()) are thought to mediate apoptosis induced by death receptor ligands, including tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). However, the role of H(2)O(2) is controversial, since some evidence suggests that H(2)O(2) acts as an anti-apoptotic factor. Here, we show that exogenously applied H(2)O(2) (30-100 µM) induces cell death in TRAIL-resistant human melanoma cells via intracellular superoxide (O(2)-) generation. H(2)O(2) induced apoptotic or necrotic cell death, depending on the concentration of the oxidant applied; low concentrations of H(2)O(2) preferentially activated the caspase-dependent apoptotic pathway, while high concentrations of H(2)O(2) induced apoptotic and necrotic cell death in a caspase-independent manner. The H(2)O(2)-induced cell death was associated with increased mitochondrial membrane potential collapse and caspase-3/7 activation and ER stress responses including caspase-12 and X-box-binding protein-1 (XBP-1) activation. H(2)O(2) induced intracellular O2- generation even within the mitochondria, while TRAIL did not. The superoxide dismutase mimetic antioxidant MnTBaP [Mn (III) tetrakis (4-benzonic acid) porphyrin chloride] inhibited the H(2)O(2)-induced O(2)- generation, apoptosis and XBP-1 and caspase-12 activation at comparable concentrations. Importantly, H(2)O(2) treatment caused minimal O(2)- generation and apoptosis in normal primary melanocytes. These data show that H(2)O(2) induces endoplasmic reticulum-associated cell death via intracellular O(2)- generation and that malignant melanoma cells are more susceptible than normal cells to this oxidative cell death. The findings suggest that H(2)O(2) has therapeutic potential in the treatment of TRAIL-resistant melanoma.

TRAIL-Based High Throughput Screening Reveals a Link between TRAIL-Mediated Apoptosis and Glutathione Reductase, a Key Component of Oxidative Stress Response

“…For example, the incubation of either bladder cancer cells or melanoma cells with low concentrations of hydrogen peroxide reverses TRAIL resistance [45, 46]. It has also been shown that quercetin, a flavonol that depletes intracellular GSH and induces ROS, can sensitize TRAIL-resistant hepatoma cells to TRAIL-induced apoptosis by multiple mechanisms [47–49].…”

Depolarization Controls TRAIL-Sensitization and Tumor-Selective Killing of Cancer Cells: Crosstalk with ROS

“…Activated IRE 1 splices the mRNA for X-box-binding protein-1 (XBP-1) to allow translation of the mature spliced form of XBP-1 protein, which acts as a transcription factor and mediates the transcriptional upregulation of numerous genes involved in ER function as well as TRAIL-R2 (25). In support of the role of ERS in TRAIL-induced apoptosis, TRAIL induces the splicing of XBP-1, and membrane-depolarizing agents including high K + , U37883A (19, 21), DATS (22), H 2 O 2 (23), and mitochondrial inhibitors such as antimycin A and FCCP (20) all commonly potentiate this effect, although none of these agents except H 2 O 2 alone can induce the splicing. Only glibenclamide cannot potentiate TRAIL-induced XBP-1 activation, although it upregulates GRP78 expression in accordance with its minimal effect on TRAIL-induced cell death during the initial 24 h (19).…”

“…These include diallyltrisulfide (DATS), a major garlic organosulfur compound (22), the cell-permeable oxidant H 2 O 2 (23), and mitochondrial metabolic inhibitors such as rotenone, antimycin A, and FCCP (20). Moreover, when employed at higher concentrations and longer exposures, all of these chemicals kill malignant cells while sparing normal cells.…”

“…A variety of natural and synthetic compounds capable of increasing the intracellular H 2 O 2 level, including LY35001 (49), wogonin (50), and diallyl polysulfides (51, 52) potentiate TRAIL cytotoxicity toward different human malignant cells (Table 3). Moreover, direct application of H 2 O 2 alone induces apoptosis or potentiates death ligand-induced apoptosis in different cell types (23, 53). In addition, various antioxidants such as N -acetyl- l -cysteine (NAC) and manganese SOD, and catalase block TNF-α- and Fas-induced apoptosis (54, 55).…”

“…Direct application of H 2 O 2 causes apoptosis in TRAIL-resistant melanoma cells and sensitizes these cells to TRAIL (23). The potentiation of apoptosis mainly occurs through the mitochondrial and ERS pathways, as shown by ΔΨ m collapse, caspase-3/7 activation, GRP-78 downregulation, and XBP-1 activation.…”