Kaempferol Suppresses Cisplatin-Induced Apoptosis Via Inductions of Heme Oxygenase-1 and Glutamate-Cysteine Ligase Catalytic Subunit in HEI-OC1 cells

The present study was undertaken to elucidate the chemoprotective mechanism of kaempferol, which possesses anti-oxidative and anti-apoptotic properties. House Ear Institute-Organ of Corti 1 (HEI-OC1) cells were treated with kaempferol in the presence or absence of cisplatin. Cisplatin-induced oxidative stress was assessed by analysis of Comet assay, DNA-laddering assay and activation of caspases. Heme oxygenase-1 (HO-1), mitogen-activated protein kinase (MAPK) pathway and nuclear factor-E2-related factor 2 (Nrf2) were measured by Western blot analysis. Transfection of small interfering RNAs (siRNA), glutathione (GSH) assay and RT-PCR were performed in this study. Kaempferol protected cells against cisplatin-induced apoptosis in a dose-dependent manner in HEI-OC1 cells. Kaempferol-induced HO-1 expression protected against cell death though the c-Jun N-terminal kinase (JNK) pathway and by the aid of Nrf2 translocation. Kaempferol increased the cellular level of GSH and the expression of GCLC time-dependently. siRNA GCLC blocked the increase of GSH level by kaempferol and the protective effect of kaempferol against cisplatin-induced cell death. The expression of HO-1 by kaempferol inhibits cisplatin-induced apoptosis in HEI-OC1 cells, and the mechanism of protective effect is also associated with its inductive effect of GCLC expression.