Effects of Simvastatin on the Expression of Heme Oxygenase-1 in Human RPE Cells

Kyoung Jin Kim, Kyong Sil Kim, Na Rae Kim, Hee Seung Chin
2012 Investigative Ophthalmology and Visual Science  
PURPOSE. Chronic oxidative stress can lead to the impairment of RPE cells, indicating it to be a risk factor for AMD. The cholesterol-independent, pleiotropic effects of statins have protective effects on several cell types via unknown mechanisms. This study examined the role of heme oxygenase-1 (HO-1) as a target and potential mediator of statins in cultured human RPE cells. METHODS. The RPE cell viability was measured using a 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay.
more » ... After 24 hours incubation, RT-PCR and Western blot was performed to measure the levels of HO-1 mRNA and protein expression, respectively, in RPE cells. Intracellular reactive oxygen species (ROS) production was measured using a fluorescence-activated cell sorter. RESULTS. In cultured human RPE cells, simvastatin showed no toxicity up to 10 lM. Simvastatin increased the HO-1 mRNA and protein levels in a concentration-dependent manner up to 10 lM. HO-1 protein induction by simvastatin was unaffected by mevalonate or N-nitro-L-arginine methyl ester, showing that the isoprenoid-and NO-dependent pathways are not involved. Simvastatin-dependent HO-1 protein induction was reduced significantly by pharmacological inhibition of the phosphotidylinositol-3-kinase (PI3K)/Akt pathways. The simvastatininduced inhibition of free radical formation was recovered by the presence of an HO inhibitor, zinc protoporphyrin. CONCLUSIONS. These results demonstrate that HO-1 is a target site and an antioxidant mediator of simvastatin in human RPE cells. Simvastatin-dependent upregulation of HO-1 is mainly via PI3K/Akt-dependent signaling pathways. Simvastatin may have some clinical benefits in preventing retinal diseases associated with oxidative stress, such as AMD. (Invest Ophthalmol Vis Sci.
doi:10.1167/iovs.12-9658 pmid:22918643 fatcat:2jc7y55kwvgi3k553camupqzuy