title: Activation of the ERK 1/2 and STAT3 signaling pathways is required for 661W cell survival following oxidant injury.
abstract: OBJECTIVE
  To evaluate the influence of hydrogen peroxide (H(2)O(2)) on mouse photoreceptor-derived 661W cell survival and to determine the effect of PD98059, an inhibitor for MEK1 (the direct upstream activator of ERK1/2), and S3I201, a STAT3- specific inhibitor on 661W cell survival after H(2)O(2) exposure.
  
  
  METHODS
  The mouse photoreceptor-derived 661W cells were cultured. 661W cells were treated for 12 hours with different concentrations (0, 0.25, 0.50, 0.75, 1mmol/L) of H(2)O(2) and cell viability was determined by 3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide ) (MTT) assay. 661W cells were treated with different concentrations H(2)O(2) (0, 5, 10, 50, 500, 1000 µmol/L) for 15 minutes or 1mmol/L H(2)O(2) for different time points (0,5,10,15,30 minutes), and p-Tyr705-STAT3, STAT3, Phospho-p44/42 MAPK (Thr202/Tyr204), ERK1/2 were surveyed by immunoblot analysis. After treatment with 50µmol/L PD98059, or S3I201 for 1 hour, the inhibition efficiency of cell signal pathways was analyzed by immunoblot analysis and the effects of inhibitors on cell viability were determined by MTT.
  
  
  RESULTS
  After treating with different concentrations of H(2)O(2) for 12 hours, the cell viability of 661W cells decreased in concentration-dependent manner (P<0.05). Moreover, H(2)O(2) induced phosphorylation of ERK1/2 and STAT3 in 661W cells (P<0.05). After pretreatment with 50µmol/L PD98059 or S3I201 for 1 hour, H(2)O(2)-induced phosphorylation of ERK1/2 or STAT3 was suppressed separately (P<0.05). Using PD98059 or S3I201 to inhibit ERK1/2 or STAT3 signal pathway, the cell viability of 661W cells decreased significantly (P<0.05).
  
  
  CONCLUSIONS
  We demonstrated that the exposure of 661W cells to H(2)O(2) increased the activation of ERK1/2 and STAT3 signal pathways. Activation of these pathways is required for 661W cell survival following oxidant injury.
authors: Department of Ophthalmology, Xiangya Hospital of Central South University, Changsha 410006, Hunan Province, China.
authors: Shu-Qian
authors: SQ
authors: Dong
authors: Hui-Zhuo
authors: HZ
authors: Xu
authors: Xiao-Bo
authors: XB
authors: Xia
authors: Sha
authors: S
authors: Wang
authors: Li-Xin
authors: LX
authors: Zhang
authors: Shuang-Zhen
authors: SZ
authors: Liu