Sodium nitroprusside induces autophagic cell death in glutathione‐depleted osteoblasts

Abstract

Previous studies reported that high levels of nitric oxide (NO) induce apoptotic cell death in osteoblasts. We examined molecular mechanisms of cytotoxic injury induced by sodium nitroprusside (SNP), a NO donor, in both glutathione (GSH)-depleted and control U2-OS osteoblasts. Cell viability was reduced by much lower effective concentrations of SNP in GSH-depleted cells compared to normal cells. The data suggest that the level of intracellular GSH is critical in SNP-induced cell death processes of osteoblasts. The level of oxidative stress due to SNP treatments doubled in GSH-depleted cells when measured with fluorochrome H2DCFDA. Pretreatment with the NO scavenger PTIO preserved the viability of cells treated with SNP. Viability of cells treated with SNP was recovered by pretreatment with Wortmannin, an autophagy inhibitor, but not by pretreatment with zVAD-fmk, a pan-specific caspase inhibitor. Large increases of LC3-II were shown by immunoblot analysis of the SNP-treated cells, and the increase was blocked by pretreatment with PTIO or Wortmannin; this implies that under GSH-depleted conditions SNP induces different molecular signaling that lead to autophagic cell death. The ultrastructural morphology of SNP-treated cells in transmission electron microscopy showed numerous autophagic vacuoles. These data suggest NO produces oxidative stress and cellular damage that culminate in autophagic cell death of GSH-depleted osteoblasts.

GS28 Protects Neuronal Cell Death Induced by Hydrogen Peroxide under Glutathione-Depleted Condition

“…Reduced GSH status was reported in various diseases including a number of neurological disorders [15]. In our previous study, depletion of GSH with BSO significantly enhanced cytotoxicity by treatment of osteoblasts and glial cells with oxidative stresses [10,16].…”

“…It was reported that oxidative stress induces necroptosis, which is a caspase-independent nonapoptotic cell death and appears morphologically similar to necrosis [8]. Recent studies demonstrated that ROS induce autophagic cell death, another type of programmed cell death distinct from apoptosis [9,10]. Molecular mechanisms in cell injury have been well demonstrated in ROS-induced apoptosis.…”

Vacuolar H+-ATPase c protects glial cell death induced by sodium nitroprusside under glutathione-depleted condition

“…Reactive nitrogen species (RNS) are directly linked to reactive oxygen species (ROS), and mammalian cells maintain ROS/RNS at low levels through antioxidant systems, such as superoxide dismutase (SOD), vitamins E and C, and glutathione (GSH) [Reiter, 1995;Son et al, 2010]. Sodium nitroprusside (SNP) is a water-soluble complex consisting of a ferrous ion surrounded by five cyanide (CN) moieties and one NO.…”

Therapeutic actions of curcumin in bone disorders

“…27 It has been shown that the constitutively NO produced by osteoblasts stimulates both osteoblastic growth and differentiation. 28 By contrast, excess local production of NO induces cytotoxicity in osteoblastic cells, 27 which is probably mediated in part by cGMP. 28 Interestingly, curcumin has been widely described to inhibit inducible NO synthase expression and NO production, at least in part via direct interference in NF-kB activation.…”