We have shown recently that
acrolein is more strongly involved in cell damage than
reactive oxygen species during
brain infarction. Thus, we tried to isolate cells with reduced susceptibility to
acrolein toxicity to clarify how
acrolein is detoxified under cell culture conditions. The IC(50) of
acrolein in mouse mammary
carcinoma FM3A cells and in
neuroblastoma Neuro2a cells was 2.6 and 4.2μM, respectively, but in
acrolein toxicity-decreasing FM3A (FM3A-ATD) cells and Neuro2a (Neuro2a-ATD) cells, it was 7.6 and 8.4μM, respectively. In both FM3A-ATD and Neuro2a-ATD cells, the concentration of
glutathione (GSH) was increased, so that detoxification occurred through
acrolein conjugation with GSH. In FM3A-ATD cells, the level of a rate-limiting
enzyme of GSH synthesis, γ-glutamylcysteine
ligase catalytic unit (GCLC), was increased through the reactivation of one inactive allele of GCLC genes in FM3A cells. In Neuro2a-ATD cells, phosphorylation of
transcription factors (c-Jun and NF-κB) necessary for expression of genes for GCLC and
glutathione synthetase (GSHS) involved in GSH synthesis was stimulated, so that transcription of two genes increased in Neuro2a-ATD cells. Phosphorylation of JNK (
c-Jun N-terminal kinase), which catalyzes phosphorylation of c-Jun and NF-κB p65, was also increased in Neuro2a-ATD cells, suggesting that activation of
JNK kinase is responsible for the increase in GSH. These results support the idea that GSH plays important roles in detoxification of
acrolein, because GSH is increased in both FM3A-ATD and Neuro2a-ATD cells.