Abstract

In this study, we investigated the effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on 1-methyl-4-phenylpyridinium (MPP⁺)-induced cell death in PC12 cells. Coincubation of PC12 cells with indomethacin, ibuprofen, ketoprofen, or diclofenac, but not aspirin or N-[2-(cyclohexyloxy)-4-nitrophenyl]methanosulfonamide (NS-398), significantly potentiated the MPP⁺-induced cell death. In contrast, these NSAIDs had no effect on rotenone-induced cell death. The potentiating actions of these NSAIDs were not suppressed by treatment with phenyl-N-butyl-nitrone, a radical scavenger; N-acetyl-l-cysteine, an antioxidant; Ac-DEVD-CHO, a selective caspase-3 inhibitor; or 2-chloro-5-nitro-N-phenylbenzamide (GW9662), a selective antagonist of peroxisome proliferator-activated receptor γ. Furthermore, we observed that DNA fragmentation, which is one of the hallmarks of apoptosis, was not induced by coincubation with MPP⁺ and NSAIDs. We confirmed that coincubation of PC12 cells with 30 μM MPP⁺ and 100 μM indomethacin, ibuprofen, ketoprofen, or diclofenac led to a significant increase in the accumulation of intracellular MPP⁺ compared with incubation with 30 μM MPP⁺ alone. In addition, these NSAIDs markedly reduced the efflux of MPP⁺ from PC12 cells. (3-(3-(2-(7-Chloro-2-quinolinyl) ethenyl) phenyl ((3-dimethyl amino-3oxo-propyl) thio) methyl) propanoic acid (MK 571), which is an inhibitor of multidrug resistance proteins (MRPs), mimicked the NSAIDs-induced effects, increasing cell toxicity and promoting the accumulation of MPP⁺. Moreover, some types of MRPs' mRNA were detected in PC12 cells. These results suggest that some NSAIDs might cause a significant increase in the intracellular accumulation of MPP⁺ via the suppression of reverse transport by the blockade of MRP, resulting in the potentiation of MPP⁺-induced cell death.