Purchase this article with an account.
C. K. Hwang, H. Zhou, R. Haque, P. M. Iuvone; NQO2: A Novel Target to Mediate Neuroprotection Against Retinal Degeneration. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3706.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Oxidative stress-induced damage to the retinal pigment epithelium (RPE) is thought to be involved in the development of AMD. In this study, we test the hypothesis that NRH:quinone oxidoreductase 2 (NQO2) inhibitors protect human RPE cells (ARPE-19) from oxidative stress. In addition, we determine if NQO2 inhibitors alter the level of the tumor-suppressor protein, p53, which may limit the clinical utility of NQO2 inhibitors in the treatment of AMD.
Total protein lysate of ARPE-19 cells was probed with antibody for NQO2. ARPE-19 cells were treated daily with melatonin, the NQO2-specific inhibitor, 5-methoxycarbonylamino-N-acetyltryptamine (MCA-NAT), or vehicle for five days and then exposed to 600 µM H2O2 for 16 hours. Cell viability was then determined by measuring intracellular conversion of resazurin to resorufin (Cell Titer Blue Viability Assay, Promega). Total protein lysate of ARPE-19 cells treated for 3 days with 10µM MCA-NAT, 10µM resveratrol (a potent inhibitor of NQO2), or vehicle was probed with antibody for p53.
Immunoblot analysis confirms the expression of NQO2 protein in human RPE cells. Melatonin or MCA-NAT protects human RPE cells from H2O2-induced oxidative stress in a concentration-dependent manner with an EC50 of approximately 0.3 µM. Pharmacologic inhibition of NQO2 does not detectably alter p53 levels in ARPE-19 cells compared to control cells in immunoblot analysis.
MCA-NAT protects ARPE-19 cells from oxidative stress at the same potency as melatonin’s, suggesting that NQO2 is the target of melatonin to mediate protection against oxidative stress. Contrary to what was observed in NQO2 knockdown cells or Nqo2 knockout mice, NQO2 inhibitors merely block the catalytic action of NQO2 and do not reduce the level of p53. Therefore, NQO2 inhibition may be a feasible treatment strategy for AMD.
This PDF is available to Subscribers Only