The mode of cisplatin-induced cell death in CYP2E1-overexpressing HepG2 cells: Modulation by ERK, ROS, glutathione, and thioredoxin

Abstract

In a previous study, E47 HepG2 cells that overexpress human CYP2E1 were shown to be more sensitive to cisplatin than C34 cells that do not express CYP2E1. In this study, we found that this sensitivity was due to an earlier activation of ERK in the E47 cells than in C34 cells. Glutathione depletion by L-buthionine sulfoximine (BSO) enhanced cisplatin cytotoxicity via increasing production of reactive oxygen species (ROS) and activation of ERK. In contrast, elevation of glutathione by glutathione ethyl ester (GSHE) decreased cisplatin/BSO cytotoxicity by decreasing ROS production and ERK activation. Inhibition of ERK activation by U0126 protected against cisplatin/BSO cytotoxicity via inhibiting ROS production but not restoring intracellular glutathione content. Examination of the mode of cell death showed that U0126 inhibited cisplatin-induced necrosis but not apoptosis. Cisplatin induced apoptosis was caspases-dependent; BSO switched cisplatin-induced apoptosis to necrosis via decreasing activities of caspases, and GSHE switched cisplatin/BSO induced necrosis back to apoptosis through maintaining activities of caspases. Similar to GSHE, U0126 partially switched cisplatin/BSO induced necrosis to apoptosis via restoring activities of caspases. Cisplatin lowered levels of thioredoxin, especially in the presence of BSO. Although U0126 failed in restoring intracellular glutathione levels, it restored thioredoxin levels which maintain activities of the caspases. These results suggest that thioredoxin can replace glutathione to promote the active thiol redox state necessary for caspase activity, and thus glutathione and thioredoxin regulate the mode of cisplatin toxicity in E47 cells via redox regulation of caspase activities.

Protective effect of L-carnitine against cisplatin-induced liver and kidney oxidant injury in rats

“…In previous studies, CDDP has been found to have an antiperoxidative effect on several tissues, such as the liver, kidney, and lens [35][36][37]. GSH is the most important molecule for maintaining cell integrity and participation in cell metabolism [38]. The role of GSH, which are non-protein thiols in the cells, in the formation of conjugates with electrophilic drug metabolites (most often formed by cytochrome P450-linked monooxygenase) is well established [39].…”

Seleno l-Methionine Acts on Cyclophosphamide-Induced Kidney Toxicity

“…GSH is the most important molecule for maintaining cell integrity and participation in cell metabolism [27]. The significant reduction in GSH levels promoted by CP represents an alteration in the cellular redox state, suggesting that the cells could be more sensitive to ROS.…”

Biological effects of a complex of vanadium(V) with salicylaldehyde semicarbazone in osteoblasts in culture: Mechanism of action

“…Since the oxidative stress is also related to the activation of ERK pathway [74,75], we tried to elucidate its involvement in the complex induced cytotoxic effects in osteoblasts as it has been previously reported for vanadate [57,74]. To achieve this aim we have used NAC and specific inhibitors of ERK pathway.…”