Stable expression of short interfering RNA for DT-diaphorase induces neurotoxicity.

DT-Diaphorase has been proposed to play a neuroprotective role in dopaminergic neurons by preventing aminochrome neurotoxicity. There are several studies supporting this idea, but in all studies, we used dicoumarol, an inhibitor of DT-diaphorase. We have designed and developed two siRNA to silence the expression of DT-diaphorase to study its role in aminochrome metabolism. We transduced RCSN-3 cells with retroviral particles containing a pRetroSuper plasmid coding a siRNA for DT-diaphorase. The cells selected in the presence of puromycin generated a stable cell line RCSN-3Nq6 and RCSN-3Nq7 with low expression of DT-diaphorase (27% and 33% of wild type, respectively). A significant cell death was observed in RCSN-3 cells expressing siRNA Nq6 and Nq7 for DT-diaphorase when were incubated with 100 μM aminochrome during 48 (4- and 3.5-fold, respectively; P < 0.01). These results support the protective role of DT-diaphorase against aminochrome neurotoxicity in dopaminergic neurons containing neuromelanin and show that Nq6 and Nq7 siRNA are very useful tools to study the role of DT-diaphorase in aminochrome metabolism.